Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 10964 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
new file mode 100644
index 000000000..f250e2083
--- /dev/null
+++ b/fs/btrfs/inode.c
@@ -0,0 +1,10964 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ */
+
+#include <crypto/hash.h>
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/blk-cgroup.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/writeback.h>
+#include <linux/compat.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl.h>
+#include <linux/falloc.h>
+#include <linux/slab.h>
+#include <linux/ratelimit.h>
+#include <linux/btrfs.h>
+#include <linux/blkdev.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/uio.h>
+#include <linux/magic.h>
+#include <linux/iversion.h>
+#include <linux/swap.h>
+#include <linux/migrate.h>
+#include <linux/sched/mm.h>
+#include <linux/iomap.h>
+#include <asm/unaligned.h>
+#include <linux/fsverity.h>
+#include "misc.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "print-tree.h"
+#include "ordered-data.h"
+#include "xattr.h"
+#include "tree-log.h"
+#include "bio.h"
+#include "compression.h"
+#include "locking.h"
+#include "free-space-cache.h"
+#include "props.h"
+#include "qgroup.h"
+#include "delalloc-space.h"
+#include "block-group.h"
+#include "space-info.h"
+#include "zoned.h"
+#include "subpage.h"
+#include "inode-item.h"
+#include "fs.h"
+#include "accessors.h"
+#include "extent-tree.h"
+#include "root-tree.h"
+#include "defrag.h"
+#include "dir-item.h"
+#include "file-item.h"
+#include "uuid-tree.h"
+#include "ioctl.h"
+#include "file.h"
+#include "acl.h"
+#include "relocation.h"
+#include "verity.h"
+#include "super.h"
+#include "orphan.h"
+#include "backref.h"
+
+struct btrfs_iget_args {
+	u64 ino;
+	struct btrfs_root *root;
+};
+
+struct btrfs_dio_data {
+	ssize_t submitted;
+	struct extent_changeset *data_reserved;
+	struct btrfs_ordered_extent *ordered;
+	bool data_space_reserved;
+	bool nocow_done;
+};
+
+struct btrfs_dio_private {
+	/* Range of I/O */
+	u64 file_offset;
+	u32 bytes;
+
+	/* This must be last */
+	struct btrfs_bio bbio;
+};
+
+static struct bio_set btrfs_dio_bioset;
+
+struct btrfs_rename_ctx {
+	/* Output field. Stores the index number of the old directory entry. */
+	u64 index;
+};
+
+/*
+ * Used by data_reloc_print_warning_inode() to pass needed info for filename
+ * resolution and output of error message.
+ */
+struct data_reloc_warn {
+	struct btrfs_path path;
+	struct btrfs_fs_info *fs_info;
+	u64 extent_item_size;
+	u64 logical;
+	int mirror_num;
+};
+
+static const struct inode_operations btrfs_dir_inode_operations;
+static const struct inode_operations btrfs_symlink_inode_operations;
+static const struct inode_operations btrfs_special_inode_operations;
+static const struct inode_operations btrfs_file_inode_operations;
+static const struct address_space_operations btrfs_aops;
+static const struct file_operations btrfs_dir_file_operations;
+
+static struct kmem_cache *btrfs_inode_cachep;
+
+static int btrfs_setsize(struct inode *inode, struct iattr *attr);
+static int btrfs_truncate(struct btrfs_inode *inode, bool skip_writeback);
+
+static noinline int run_delalloc_cow(struct btrfs_inode *inode,
+				     struct page *locked_page, u64 start,
+				     u64 end, struct writeback_control *wbc,
+				     bool pages_dirty);
+static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
+				       u64 len, u64 orig_start, u64 block_start,
+				       u64 block_len, u64 orig_block_len,
+				       u64 ram_bytes, int compress_type,
+				       int type);
+
+static int data_reloc_print_warning_inode(u64 inum, u64 offset, u64 num_bytes,
+					  u64 root, void *warn_ctx)
+{
+	struct data_reloc_warn *warn = warn_ctx;
+	struct btrfs_fs_info *fs_info = warn->fs_info;
+	struct extent_buffer *eb;
+	struct btrfs_inode_item *inode_item;
+	struct inode_fs_paths *ipath = NULL;
+	struct btrfs_root *local_root;
+	struct btrfs_key key;
+	unsigned int nofs_flag;
+	u32 nlink;
+	int ret;
+
+	local_root = btrfs_get_fs_root(fs_info, root, true);
+	if (IS_ERR(local_root)) {
+		ret = PTR_ERR(local_root);
+		goto err;
+	}
+
+	/* This makes the path point to (inum INODE_ITEM ioff). */
+	key.objectid = inum;
+	key.type = BTRFS_INODE_ITEM_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, local_root, &key, &warn->path, 0, 0);
+	if (ret) {
+		btrfs_put_root(local_root);
+		btrfs_release_path(&warn->path);
+		goto err;
+	}
+
+	eb = warn->path.nodes[0];
+	inode_item = btrfs_item_ptr(eb, warn->path.slots[0], struct btrfs_inode_item);
+	nlink = btrfs_inode_nlink(eb, inode_item);
+	btrfs_release_path(&warn->path);
+
+	nofs_flag = memalloc_nofs_save();
+	ipath = init_ipath(4096, local_root, &warn->path);
+	memalloc_nofs_restore(nofs_flag);
+	if (IS_ERR(ipath)) {
+		btrfs_put_root(local_root);
+		ret = PTR_ERR(ipath);
+		ipath = NULL;
+		/*
+		 * -ENOMEM, not a critical error, just output an generic error
+		 * without filename.
+		 */
+		btrfs_warn(fs_info,
+"checksum error at logical %llu mirror %u root %llu, inode %llu offset %llu",
+			   warn->logical, warn->mirror_num, root, inum, offset);
+		return ret;
+	}
+	ret = paths_from_inode(inum, ipath);
+	if (ret < 0)
+		goto err;
+
+	/*
+	 * We deliberately ignore the bit ipath might have been too small to
+	 * hold all of the paths here
+	 */
+	for (int i = 0; i < ipath->fspath->elem_cnt; i++) {
+		btrfs_warn(fs_info,
+"checksum error at logical %llu mirror %u root %llu inode %llu offset %llu length %u links %u (path: %s)",
+			   warn->logical, warn->mirror_num, root, inum, offset,
+			   fs_info->sectorsize, nlink,
+			   (char *)(unsigned long)ipath->fspath->val[i]);
+	}
+
+	btrfs_put_root(local_root);
+	free_ipath(ipath);
+	return 0;
+
+err:
+	btrfs_warn(fs_info,
+"checksum error at logical %llu mirror %u root %llu inode %llu offset %llu, path resolving failed with ret=%d",
+		   warn->logical, warn->mirror_num, root, inum, offset, ret);
+
+	free_ipath(ipath);
+	return ret;
+}
+
+/*
+ * Do extra user-friendly error output (e.g. lookup all the affected files).
+ *
+ * Return true if we succeeded doing the backref lookup.
+ * Return false if such lookup failed, and has to fallback to the old error message.
+ */
+static void print_data_reloc_error(const struct btrfs_inode *inode, u64 file_off,
+				   const u8 *csum, const u8 *csum_expected,
+				   int mirror_num)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_path path = { 0 };
+	struct btrfs_key found_key = { 0 };
+	struct extent_buffer *eb;
+	struct btrfs_extent_item *ei;
+	const u32 csum_size = fs_info->csum_size;
+	u64 logical;
+	u64 flags;
+	u32 item_size;
+	int ret;
+
+	mutex_lock(&fs_info->reloc_mutex);
+	logical = btrfs_get_reloc_bg_bytenr(fs_info);
+	mutex_unlock(&fs_info->reloc_mutex);
+
+	if (logical == U64_MAX) {
+		btrfs_warn_rl(fs_info, "has data reloc tree but no running relocation");
+		btrfs_warn_rl(fs_info,
+"csum failed root %lld ino %llu off %llu csum " CSUM_FMT " expected csum " CSUM_FMT " mirror %d",
+			inode->root->root_key.objectid, btrfs_ino(inode), file_off,
+			CSUM_FMT_VALUE(csum_size, csum),
+			CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+		return;
+	}
+
+	logical += file_off;
+	btrfs_warn_rl(fs_info,
+"csum failed root %lld ino %llu off %llu logical %llu csum " CSUM_FMT " expected csum " CSUM_FMT " mirror %d",
+			inode->root->root_key.objectid,
+			btrfs_ino(inode), file_off, logical,
+			CSUM_FMT_VALUE(csum_size, csum),
+			CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+
+	ret = extent_from_logical(fs_info, logical, &path, &found_key, &flags);
+	if (ret < 0) {
+		btrfs_err_rl(fs_info, "failed to lookup extent item for logical %llu: %d",
+			     logical, ret);
+		return;
+	}
+	eb = path.nodes[0];
+	ei = btrfs_item_ptr(eb, path.slots[0], struct btrfs_extent_item);
+	item_size = btrfs_item_size(eb, path.slots[0]);
+	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+		unsigned long ptr = 0;
+		u64 ref_root;
+		u8 ref_level;
+
+		while (true) {
+			ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
+						      item_size, &ref_root,
+						      &ref_level);
+			if (ret < 0) {
+				btrfs_warn_rl(fs_info,
+				"failed to resolve tree backref for logical %llu: %d",
+					      logical, ret);
+				break;
+			}
+			if (ret > 0)
+				break;
+
+			btrfs_warn_rl(fs_info,
+"csum error at logical %llu mirror %u: metadata %s (level %d) in tree %llu",
+				logical, mirror_num,
+				(ref_level ? "node" : "leaf"),
+				ref_level, ref_root);
+		}
+		btrfs_release_path(&path);
+	} else {
+		struct btrfs_backref_walk_ctx ctx = { 0 };
+		struct data_reloc_warn reloc_warn = { 0 };
+
+		btrfs_release_path(&path);
+
+		ctx.bytenr = found_key.objectid;
+		ctx.extent_item_pos = logical - found_key.objectid;
+		ctx.fs_info = fs_info;
+
+		reloc_warn.logical = logical;
+		reloc_warn.extent_item_size = found_key.offset;
+		reloc_warn.mirror_num = mirror_num;
+		reloc_warn.fs_info = fs_info;
+
+		iterate_extent_inodes(&ctx, true,
+				      data_reloc_print_warning_inode, &reloc_warn);
+	}
+}
+
+static void __cold btrfs_print_data_csum_error(struct btrfs_inode *inode,
+		u64 logical_start, u8 *csum, u8 *csum_expected, int mirror_num)
+{
+	struct btrfs_root *root = inode->root;
+	const u32 csum_size = root->fs_info->csum_size;
+
+	/* For data reloc tree, it's better to do a backref lookup instead. */
+	if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
+		return print_data_reloc_error(inode, logical_start, csum,
+					      csum_expected, mirror_num);
+
+	/* Output without objectid, which is more meaningful */
+	if (root->root_key.objectid >= BTRFS_LAST_FREE_OBJECTID) {
+		btrfs_warn_rl(root->fs_info,
+"csum failed root %lld ino %lld off %llu csum " CSUM_FMT " expected csum " CSUM_FMT " mirror %d",
+			root->root_key.objectid, btrfs_ino(inode),
+			logical_start,
+			CSUM_FMT_VALUE(csum_size, csum),
+			CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+	} else {
+		btrfs_warn_rl(root->fs_info,
+"csum failed root %llu ino %llu off %llu csum " CSUM_FMT " expected csum " CSUM_FMT " mirror %d",
+			root->root_key.objectid, btrfs_ino(inode),
+			logical_start,
+			CSUM_FMT_VALUE(csum_size, csum),
+			CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+	}
+}
+
+/*
+ * btrfs_inode_lock - lock inode i_rwsem based on arguments passed
+ *
+ * ilock_flags can have the following bit set:
+ *
+ * BTRFS_ILOCK_SHARED - acquire a shared lock on the inode
+ * BTRFS_ILOCK_TRY - try to acquire the lock, if fails on first attempt
+ *		     return -EAGAIN
+ * BTRFS_ILOCK_MMAP - acquire a write lock on the i_mmap_lock
+ */
+int btrfs_inode_lock(struct btrfs_inode *inode, unsigned int ilock_flags)
+{
+	if (ilock_flags & BTRFS_ILOCK_SHARED) {
+		if (ilock_flags & BTRFS_ILOCK_TRY) {
+			if (!inode_trylock_shared(&inode->vfs_inode))
+				return -EAGAIN;
+			else
+				return 0;
+		}
+		inode_lock_shared(&inode->vfs_inode);
+	} else {
+		if (ilock_flags & BTRFS_ILOCK_TRY) {
+			if (!inode_trylock(&inode->vfs_inode))
+				return -EAGAIN;
+			else
+				return 0;
+		}
+		inode_lock(&inode->vfs_inode);
+	}
+	if (ilock_flags & BTRFS_ILOCK_MMAP)
+		down_write(&inode->i_mmap_lock);
+	return 0;
+}
+
+/*
+ * btrfs_inode_unlock - unock inode i_rwsem
+ *
+ * ilock_flags should contain the same bits set as passed to btrfs_inode_lock()
+ * to decide whether the lock acquired is shared or exclusive.
+ */
+void btrfs_inode_unlock(struct btrfs_inode *inode, unsigned int ilock_flags)
+{
+	if (ilock_flags & BTRFS_ILOCK_MMAP)
+		up_write(&inode->i_mmap_lock);
+	if (ilock_flags & BTRFS_ILOCK_SHARED)
+		inode_unlock_shared(&inode->vfs_inode);
+	else
+		inode_unlock(&inode->vfs_inode);
+}
+
+/*
+ * Cleanup all submitted ordered extents in specified range to handle errors
+ * from the btrfs_run_delalloc_range() callback.
+ *
+ * NOTE: caller must ensure that when an error happens, it can not call
+ * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING
+ * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata
+ * to be released, which we want to happen only when finishing the ordered
+ * extent (btrfs_finish_ordered_io()).
+ */
+static inline void btrfs_cleanup_ordered_extents(struct btrfs_inode *inode,
+						 struct page *locked_page,
+						 u64 offset, u64 bytes)
+{
+	unsigned long index = offset >> PAGE_SHIFT;
+	unsigned long end_index = (offset + bytes - 1) >> PAGE_SHIFT;
+	u64 page_start = 0, page_end = 0;
+	struct page *page;
+
+	if (locked_page) {
+		page_start = page_offset(locked_page);
+		page_end = page_start + PAGE_SIZE - 1;
+	}
+
+	while (index <= end_index) {
+		/*
+		 * For locked page, we will call btrfs_mark_ordered_io_finished
+		 * through btrfs_mark_ordered_io_finished() on it
+		 * in run_delalloc_range() for the error handling, which will
+		 * clear page Ordered and run the ordered extent accounting.
+		 *
+		 * Here we can't just clear the Ordered bit, or
+		 * btrfs_mark_ordered_io_finished() would skip the accounting
+		 * for the page range, and the ordered extent will never finish.
+		 */
+		if (locked_page && index == (page_start >> PAGE_SHIFT)) {
+			index++;
+			continue;
+		}
+		page = find_get_page(inode->vfs_inode.i_mapping, index);
+		index++;
+		if (!page)
+			continue;
+
+		/*
+		 * Here we just clear all Ordered bits for every page in the
+		 * range, then btrfs_mark_ordered_io_finished() will handle
+		 * the ordered extent accounting for the range.
+		 */
+		btrfs_page_clamp_clear_ordered(inode->root->fs_info, page,
+					       offset, bytes);
+		put_page(page);
+	}
+
+	if (locked_page) {
+		/* The locked page covers the full range, nothing needs to be done */
+		if (bytes + offset <= page_start + PAGE_SIZE)
+			return;
+		/*
+		 * In case this page belongs to the delalloc range being
+		 * instantiated then skip it, since the first page of a range is
+		 * going to be properly cleaned up by the caller of
+		 * run_delalloc_range
+		 */
+		if (page_start >= offset && page_end <= (offset + bytes - 1)) {
+			bytes = offset + bytes - page_offset(locked_page) - PAGE_SIZE;
+			offset = page_offset(locked_page) + PAGE_SIZE;
+		}
+	}
+
+	return btrfs_mark_ordered_io_finished(inode, NULL, offset, bytes, false);
+}
+
+static int btrfs_dirty_inode(struct btrfs_inode *inode);
+
+static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
+				     struct btrfs_new_inode_args *args)
+{
+	int err;
+
+	if (args->default_acl) {
+		err = __btrfs_set_acl(trans, args->inode, args->default_acl,
+				      ACL_TYPE_DEFAULT);
+		if (err)
+			return err;
+	}
+	if (args->acl) {
+		err = __btrfs_set_acl(trans, args->inode, args->acl, ACL_TYPE_ACCESS);
+		if (err)
+			return err;
+	}
+	if (!args->default_acl && !args->acl)
+		cache_no_acl(args->inode);
+	return btrfs_xattr_security_init(trans, args->inode, args->dir,
+					 &args->dentry->d_name);
+}
+
+/*
+ * this does all the hard work for inserting an inline extent into
+ * the btree.  The caller should have done a btrfs_drop_extents so that
+ * no overlapping inline items exist in the btree
+ */
+static int insert_inline_extent(struct btrfs_trans_handle *trans,
+				struct btrfs_path *path,
+				struct btrfs_inode *inode, bool extent_inserted,
+				size_t size, size_t compressed_size,
+				int compress_type,
+				struct page **compressed_pages,
+				bool update_i_size)
+{
+	struct btrfs_root *root = inode->root;
+	struct extent_buffer *leaf;
+	struct page *page = NULL;
+	char *kaddr;
+	unsigned long ptr;
+	struct btrfs_file_extent_item *ei;
+	int ret;
+	size_t cur_size = size;
+	u64 i_size;
+
+	ASSERT((compressed_size > 0 && compressed_pages) ||
+	       (compressed_size == 0 && !compressed_pages));
+
+	if (compressed_size && compressed_pages)
+		cur_size = compressed_size;
+
+	if (!extent_inserted) {
+		struct btrfs_key key;
+		size_t datasize;
+
+		key.objectid = btrfs_ino(inode);
+		key.offset = 0;
+		key.type = BTRFS_EXTENT_DATA_KEY;
+
+		datasize = btrfs_file_extent_calc_inline_size(cur_size);
+		ret = btrfs_insert_empty_item(trans, root, path, &key,
+					      datasize);
+		if (ret)
+			goto fail;
+	}
+	leaf = path->nodes[0];
+	ei = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, ei, trans->transid);
+	btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
+	btrfs_set_file_extent_encryption(leaf, ei, 0);
+	btrfs_set_file_extent_other_encoding(leaf, ei, 0);
+	btrfs_set_file_extent_ram_bytes(leaf, ei, size);
+	ptr = btrfs_file_extent_inline_start(ei);
+
+	if (compress_type != BTRFS_COMPRESS_NONE) {
+		struct page *cpage;
+		int i = 0;
+		while (compressed_size > 0) {
+			cpage = compressed_pages[i];
+			cur_size = min_t(unsigned long, compressed_size,
+				       PAGE_SIZE);
+
+			kaddr = kmap_local_page(cpage);
+			write_extent_buffer(leaf, kaddr, ptr, cur_size);
+			kunmap_local(kaddr);
+
+			i++;
+			ptr += cur_size;
+			compressed_size -= cur_size;
+		}
+		btrfs_set_file_extent_compression(leaf, ei,
+						  compress_type);
+	} else {
+		page = find_get_page(inode->vfs_inode.i_mapping, 0);
+		btrfs_set_file_extent_compression(leaf, ei, 0);
+		kaddr = kmap_local_page(page);
+		write_extent_buffer(leaf, kaddr, ptr, size);
+		kunmap_local(kaddr);
+		put_page(page);
+	}
+	btrfs_mark_buffer_dirty(trans, leaf);
+	btrfs_release_path(path);
+
+	/*
+	 * We align size to sectorsize for inline extents just for simplicity
+	 * sake.
+	 */
+	ret = btrfs_inode_set_file_extent_range(inode, 0,
+					ALIGN(size, root->fs_info->sectorsize));
+	if (ret)
+		goto fail;
+
+	/*
+	 * We're an inline extent, so nobody can extend the file past i_size
+	 * without locking a page we already have locked.
+	 *
+	 * We must do any i_size and inode updates before we unlock the pages.
+	 * Otherwise we could end up racing with unlink.
+	 */
+	i_size = i_size_read(&inode->vfs_inode);
+	if (update_i_size && size > i_size) {
+		i_size_write(&inode->vfs_inode, size);
+		i_size = size;
+	}
+	inode->disk_i_size = i_size;
+
+fail:
+	return ret;
+}
+
+
+/*
+ * conditionally insert an inline extent into the file.  This
+ * does the checks required to make sure the data is small enough
+ * to fit as an inline extent.
+ */
+static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 size,
+					  size_t compressed_size,
+					  int compress_type,
+					  struct page **compressed_pages,
+					  bool update_i_size)
+{
+	struct btrfs_drop_extents_args drop_args = { 0 };
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	u64 data_len = (compressed_size ?: size);
+	int ret;
+	struct btrfs_path *path;
+
+	/*
+	 * We can create an inline extent if it ends at or beyond the current
+	 * i_size, is no larger than a sector (decompressed), and the (possibly
+	 * compressed) data fits in a leaf and the configured maximum inline
+	 * size.
+	 */
+	if (size < i_size_read(&inode->vfs_inode) ||
+	    size > fs_info->sectorsize ||
+	    data_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
+	    data_len > fs_info->max_inline)
+		return 1;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		btrfs_free_path(path);
+		return PTR_ERR(trans);
+	}
+	trans->block_rsv = &inode->block_rsv;
+
+	drop_args.path = path;
+	drop_args.start = 0;
+	drop_args.end = fs_info->sectorsize;
+	drop_args.drop_cache = true;
+	drop_args.replace_extent = true;
+	drop_args.extent_item_size = btrfs_file_extent_calc_inline_size(data_len);
+	ret = btrfs_drop_extents(trans, root, inode, &drop_args);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	ret = insert_inline_extent(trans, path, inode, drop_args.extent_inserted,
+				   size, compressed_size, compress_type,
+				   compressed_pages, update_i_size);
+	if (ret && ret != -ENOSPC) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	} else if (ret == -ENOSPC) {
+		ret = 1;
+		goto out;
+	}
+
+	btrfs_update_inode_bytes(inode, size, drop_args.bytes_found);
+	ret = btrfs_update_inode(trans, root, inode);
+	if (ret && ret != -ENOSPC) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	} else if (ret == -ENOSPC) {
+		ret = 1;
+		goto out;
+	}
+
+	btrfs_set_inode_full_sync(inode);
+out:
+	/*
+	 * Don't forget to free the reserved space, as for inlined extent
+	 * it won't count as data extent, free them directly here.
+	 * And at reserve time, it's always aligned to page size, so
+	 * just free one page here.
+	 */
+	btrfs_qgroup_free_data(inode, NULL, 0, PAGE_SIZE, NULL);
+	btrfs_free_path(path);
+	btrfs_end_transaction(trans);
+	return ret;
+}
+
+struct async_extent {
+	u64 start;
+	u64 ram_size;
+	u64 compressed_size;
+	struct page **pages;
+	unsigned long nr_pages;
+	int compress_type;
+	struct list_head list;
+};
+
+struct async_chunk {
+	struct btrfs_inode *inode;
+	struct page *locked_page;
+	u64 start;
+	u64 end;
+	blk_opf_t write_flags;
+	struct list_head extents;
+	struct cgroup_subsys_state *blkcg_css;
+	struct btrfs_work work;
+	struct async_cow *async_cow;
+};
+
+struct async_cow {
+	atomic_t num_chunks;
+	struct async_chunk chunks[];
+};
+
+static noinline int add_async_extent(struct async_chunk *cow,
+				     u64 start, u64 ram_size,
+				     u64 compressed_size,
+				     struct page **pages,
+				     unsigned long nr_pages,
+				     int compress_type)
+{
+	struct async_extent *async_extent;
+
+	async_extent = kmalloc(sizeof(*async_extent), GFP_NOFS);
+	BUG_ON(!async_extent); /* -ENOMEM */
+	async_extent->start = start;
+	async_extent->ram_size = ram_size;
+	async_extent->compressed_size = compressed_size;
+	async_extent->pages = pages;
+	async_extent->nr_pages = nr_pages;
+	async_extent->compress_type = compress_type;
+	list_add_tail(&async_extent->list, &cow->extents);
+	return 0;
+}
+
+/*
+ * Check if the inode needs to be submitted to compression, based on mount
+ * options, defragmentation, properties or heuristics.
+ */
+static inline int inode_need_compress(struct btrfs_inode *inode, u64 start,
+				      u64 end)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	if (!btrfs_inode_can_compress(inode)) {
+		WARN(IS_ENABLED(CONFIG_BTRFS_DEBUG),
+			KERN_ERR "BTRFS: unexpected compression for ino %llu\n",
+			btrfs_ino(inode));
+		return 0;
+	}
+	/*
+	 * Special check for subpage.
+	 *
+	 * We lock the full page then run each delalloc range in the page, thus
+	 * for the following case, we will hit some subpage specific corner case:
+	 *
+	 * 0		32K		64K
+	 * |	|///////|	|///////|
+	 *		\- A		\- B
+	 *
+	 * In above case, both range A and range B will try to unlock the full
+	 * page [0, 64K), causing the one finished later will have page
+	 * unlocked already, triggering various page lock requirement BUG_ON()s.
+	 *
+	 * So here we add an artificial limit that subpage compression can only
+	 * if the range is fully page aligned.
+	 *
+	 * In theory we only need to ensure the first page is fully covered, but
+	 * the tailing partial page will be locked until the full compression
+	 * finishes, delaying the write of other range.
+	 *
+	 * TODO: Make btrfs_run_delalloc_range() to lock all delalloc range
+	 * first to prevent any submitted async extent to unlock the full page.
+	 * By this, we can ensure for subpage case that only the last async_cow
+	 * will unlock the full page.
+	 */
+	if (fs_info->sectorsize < PAGE_SIZE) {
+		if (!PAGE_ALIGNED(start) ||
+		    !PAGE_ALIGNED(end + 1))
+			return 0;
+	}
+
+	/* force compress */
+	if (btrfs_test_opt(fs_info, FORCE_COMPRESS))
+		return 1;
+	/* defrag ioctl */
+	if (inode->defrag_compress)
+		return 1;
+	/* bad compression ratios */
+	if (inode->flags & BTRFS_INODE_NOCOMPRESS)
+		return 0;
+	if (btrfs_test_opt(fs_info, COMPRESS) ||
+	    inode->flags & BTRFS_INODE_COMPRESS ||
+	    inode->prop_compress)
+		return btrfs_compress_heuristic(&inode->vfs_inode, start, end);
+	return 0;
+}
+
+static inline void inode_should_defrag(struct btrfs_inode *inode,
+		u64 start, u64 end, u64 num_bytes, u32 small_write)
+{
+	/* If this is a small write inside eof, kick off a defrag */
+	if (num_bytes < small_write &&
+	    (start > 0 || end + 1 < inode->disk_i_size))
+		btrfs_add_inode_defrag(NULL, inode, small_write);
+}
+
+/*
+ * Work queue call back to started compression on a file and pages.
+ *
+ * This is done inside an ordered work queue, and the compression is spread
+ * across many cpus.  The actual IO submission is step two, and the ordered work
+ * queue takes care of making sure that happens in the same order things were
+ * put onto the queue by writepages and friends.
+ *
+ * If this code finds it can't get good compression, it puts an entry onto the
+ * work queue to write the uncompressed bytes.  This makes sure that both
+ * compressed inodes and uncompressed inodes are written in the same order that
+ * the flusher thread sent them down.
+ */
+static void compress_file_range(struct btrfs_work *work)
+{
+	struct async_chunk *async_chunk =
+		container_of(work, struct async_chunk, work);
+	struct btrfs_inode *inode = async_chunk->inode;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct address_space *mapping = inode->vfs_inode.i_mapping;
+	u64 blocksize = fs_info->sectorsize;
+	u64 start = async_chunk->start;
+	u64 end = async_chunk->end;
+	u64 actual_end;
+	u64 i_size;
+	int ret = 0;
+	struct page **pages;
+	unsigned long nr_pages;
+	unsigned long total_compressed = 0;
+	unsigned long total_in = 0;
+	unsigned int poff;
+	int i;
+	int compress_type = fs_info->compress_type;
+
+	inode_should_defrag(inode, start, end, end - start + 1, SZ_16K);
+
+	/*
+	 * We need to call clear_page_dirty_for_io on each page in the range.
+	 * Otherwise applications with the file mmap'd can wander in and change
+	 * the page contents while we are compressing them.
+	 */
+	extent_range_clear_dirty_for_io(&inode->vfs_inode, start, end);
+
+	/*
+	 * We need to save i_size before now because it could change in between
+	 * us evaluating the size and assigning it.  This is because we lock and
+	 * unlock the page in truncate and fallocate, and then modify the i_size
+	 * later on.
+	 *
+	 * The barriers are to emulate READ_ONCE, remove that once i_size_read
+	 * does that for us.
+	 */
+	barrier();
+	i_size = i_size_read(&inode->vfs_inode);
+	barrier();
+	actual_end = min_t(u64, i_size, end + 1);
+again:
+	pages = NULL;
+	nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
+	nr_pages = min_t(unsigned long, nr_pages, BTRFS_MAX_COMPRESSED_PAGES);
+
+	/*
+	 * we don't want to send crud past the end of i_size through
+	 * compression, that's just a waste of CPU time.  So, if the
+	 * end of the file is before the start of our current
+	 * requested range of bytes, we bail out to the uncompressed
+	 * cleanup code that can deal with all of this.
+	 *
+	 * It isn't really the fastest way to fix things, but this is a
+	 * very uncommon corner.
+	 */
+	if (actual_end <= start)
+		goto cleanup_and_bail_uncompressed;
+
+	total_compressed = actual_end - start;
+
+	/*
+	 * Skip compression for a small file range(<=blocksize) that
+	 * isn't an inline extent, since it doesn't save disk space at all.
+	 */
+	if (total_compressed <= blocksize &&
+	   (start > 0 || end + 1 < inode->disk_i_size))
+		goto cleanup_and_bail_uncompressed;
+
+	/*
+	 * For subpage case, we require full page alignment for the sector
+	 * aligned range.
+	 * Thus we must also check against @actual_end, not just @end.
+	 */
+	if (blocksize < PAGE_SIZE) {
+		if (!PAGE_ALIGNED(start) ||
+		    !PAGE_ALIGNED(round_up(actual_end, blocksize)))
+			goto cleanup_and_bail_uncompressed;
+	}
+
+	total_compressed = min_t(unsigned long, total_compressed,
+			BTRFS_MAX_UNCOMPRESSED);
+	total_in = 0;
+	ret = 0;
+
+	/*
+	 * We do compression for mount -o compress and when the inode has not
+	 * been flagged as NOCOMPRESS.  This flag can change at any time if we
+	 * discover bad compression ratios.
+	 */
+	if (!inode_need_compress(inode, start, end))
+		goto cleanup_and_bail_uncompressed;
+
+	pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
+	if (!pages) {
+		/*
+		 * Memory allocation failure is not a fatal error, we can fall
+		 * back to uncompressed code.
+		 */
+		goto cleanup_and_bail_uncompressed;
+	}
+
+	if (inode->defrag_compress)
+		compress_type = inode->defrag_compress;
+	else if (inode->prop_compress)
+		compress_type = inode->prop_compress;
+
+	/* Compression level is applied here. */
+	ret = btrfs_compress_pages(compress_type | (fs_info->compress_level << 4),
+				   mapping, start, pages, &nr_pages, &total_in,
+				   &total_compressed);
+	if (ret)
+		goto mark_incompressible;
+
+	/*
+	 * Zero the tail end of the last page, as we might be sending it down
+	 * to disk.
+	 */
+	poff = offset_in_page(total_compressed);
+	if (poff)
+		memzero_page(pages[nr_pages - 1], poff, PAGE_SIZE - poff);
+
+	/*
+	 * Try to create an inline extent.
+	 *
+	 * If we didn't compress the entire range, try to create an uncompressed
+	 * inline extent, else a compressed one.
+	 *
+	 * Check cow_file_range() for why we don't even try to create inline
+	 * extent for the subpage case.
+	 */
+	if (start == 0 && fs_info->sectorsize == PAGE_SIZE) {
+		if (total_in < actual_end) {
+			ret = cow_file_range_inline(inode, actual_end, 0,
+						    BTRFS_COMPRESS_NONE, NULL,
+						    false);
+		} else {
+			ret = cow_file_range_inline(inode, actual_end,
+						    total_compressed,
+						    compress_type, pages,
+						    false);
+		}
+		if (ret <= 0) {
+			unsigned long clear_flags = EXTENT_DELALLOC |
+				EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
+				EXTENT_DO_ACCOUNTING;
+
+			if (ret < 0)
+				mapping_set_error(mapping, -EIO);
+
+			/*
+			 * inline extent creation worked or returned error,
+			 * we don't need to create any more async work items.
+			 * Unlock and free up our temp pages.
+			 *
+			 * We use DO_ACCOUNTING here because we need the
+			 * delalloc_release_metadata to be done _after_ we drop
+			 * our outstanding extent for clearing delalloc for this
+			 * range.
+			 */
+			extent_clear_unlock_delalloc(inode, start, end,
+						     NULL,
+						     clear_flags,
+						     PAGE_UNLOCK |
+						     PAGE_START_WRITEBACK |
+						     PAGE_END_WRITEBACK);
+			goto free_pages;
+		}
+	}
+
+	/*
+	 * We aren't doing an inline extent. Round the compressed size up to a
+	 * block size boundary so the allocator does sane things.
+	 */
+	total_compressed = ALIGN(total_compressed, blocksize);
+
+	/*
+	 * One last check to make sure the compression is really a win, compare
+	 * the page count read with the blocks on disk, compression must free at
+	 * least one sector.
+	 */
+	total_in = round_up(total_in, fs_info->sectorsize);
+	if (total_compressed + blocksize > total_in)
+		goto mark_incompressible;
+
+	/*
+	 * The async work queues will take care of doing actual allocation on
+	 * disk for these compressed pages, and will submit the bios.
+	 */
+	add_async_extent(async_chunk, start, total_in, total_compressed, pages,
+			 nr_pages, compress_type);
+	if (start + total_in < end) {
+		start += total_in;
+		cond_resched();
+		goto again;
+	}
+	return;
+
+mark_incompressible:
+	if (!btrfs_test_opt(fs_info, FORCE_COMPRESS) && !inode->prop_compress)
+		inode->flags |= BTRFS_INODE_NOCOMPRESS;
+cleanup_and_bail_uncompressed:
+	add_async_extent(async_chunk, start, end - start + 1, 0, NULL, 0,
+			 BTRFS_COMPRESS_NONE);
+free_pages:
+	if (pages) {
+		for (i = 0; i < nr_pages; i++) {
+			WARN_ON(pages[i]->mapping);
+			put_page(pages[i]);
+		}
+		kfree(pages);
+	}
+}
+
+static void free_async_extent_pages(struct async_extent *async_extent)
+{
+	int i;
+
+	if (!async_extent->pages)
+		return;
+
+	for (i = 0; i < async_extent->nr_pages; i++) {
+		WARN_ON(async_extent->pages[i]->mapping);
+		put_page(async_extent->pages[i]);
+	}
+	kfree(async_extent->pages);
+	async_extent->nr_pages = 0;
+	async_extent->pages = NULL;
+}
+
+static void submit_uncompressed_range(struct btrfs_inode *inode,
+				      struct async_extent *async_extent,
+				      struct page *locked_page)
+{
+	u64 start = async_extent->start;
+	u64 end = async_extent->start + async_extent->ram_size - 1;
+	int ret;
+	struct writeback_control wbc = {
+		.sync_mode		= WB_SYNC_ALL,
+		.range_start		= start,
+		.range_end		= end,
+		.no_cgroup_owner	= 1,
+	};
+
+	wbc_attach_fdatawrite_inode(&wbc, &inode->vfs_inode);
+	ret = run_delalloc_cow(inode, locked_page, start, end, &wbc, false);
+	wbc_detach_inode(&wbc);
+	if (ret < 0) {
+		btrfs_cleanup_ordered_extents(inode, locked_page, start, end - start + 1);
+		if (locked_page) {
+			const u64 page_start = page_offset(locked_page);
+
+			set_page_writeback(locked_page);
+			end_page_writeback(locked_page);
+			btrfs_mark_ordered_io_finished(inode, locked_page,
+						       page_start, PAGE_SIZE,
+						       !ret);
+			mapping_set_error(locked_page->mapping, ret);
+			unlock_page(locked_page);
+		}
+	}
+}
+
+static void submit_one_async_extent(struct async_chunk *async_chunk,
+				    struct async_extent *async_extent,
+				    u64 *alloc_hint)
+{
+	struct btrfs_inode *inode = async_chunk->inode;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_key ins;
+	struct page *locked_page = NULL;
+	struct extent_map *em;
+	int ret = 0;
+	u64 start = async_extent->start;
+	u64 end = async_extent->start + async_extent->ram_size - 1;
+
+	if (async_chunk->blkcg_css)
+		kthread_associate_blkcg(async_chunk->blkcg_css);
+
+	/*
+	 * If async_chunk->locked_page is in the async_extent range, we need to
+	 * handle it.
+	 */
+	if (async_chunk->locked_page) {
+		u64 locked_page_start = page_offset(async_chunk->locked_page);
+		u64 locked_page_end = locked_page_start + PAGE_SIZE - 1;
+
+		if (!(start >= locked_page_end || end <= locked_page_start))
+			locked_page = async_chunk->locked_page;
+	}
+	lock_extent(io_tree, start, end, NULL);
+
+	if (async_extent->compress_type == BTRFS_COMPRESS_NONE) {
+		submit_uncompressed_range(inode, async_extent, locked_page);
+		goto done;
+	}
+
+	ret = btrfs_reserve_extent(root, async_extent->ram_size,
+				   async_extent->compressed_size,
+				   async_extent->compressed_size,
+				   0, *alloc_hint, &ins, 1, 1);
+	if (ret) {
+		/*
+		 * Here we used to try again by going back to non-compressed
+		 * path for ENOSPC.  But we can't reserve space even for
+		 * compressed size, how could it work for uncompressed size
+		 * which requires larger size?  So here we directly go error
+		 * path.
+		 */
+		goto out_free;
+	}
+
+	/* Here we're doing allocation and writeback of the compressed pages */
+	em = create_io_em(inode, start,
+			  async_extent->ram_size,	/* len */
+			  start,			/* orig_start */
+			  ins.objectid,			/* block_start */
+			  ins.offset,			/* block_len */
+			  ins.offset,			/* orig_block_len */
+			  async_extent->ram_size,	/* ram_bytes */
+			  async_extent->compress_type,
+			  BTRFS_ORDERED_COMPRESSED);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out_free_reserve;
+	}
+	free_extent_map(em);
+
+	ordered = btrfs_alloc_ordered_extent(inode, start,	/* file_offset */
+				       async_extent->ram_size,	/* num_bytes */
+				       async_extent->ram_size,	/* ram_bytes */
+				       ins.objectid,		/* disk_bytenr */
+				       ins.offset,		/* disk_num_bytes */
+				       0,			/* offset */
+				       1 << BTRFS_ORDERED_COMPRESSED,
+				       async_extent->compress_type);
+	if (IS_ERR(ordered)) {
+		btrfs_drop_extent_map_range(inode, start, end, false);
+		ret = PTR_ERR(ordered);
+		goto out_free_reserve;
+	}
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+
+	/* Clear dirty, set writeback and unlock the pages. */
+	extent_clear_unlock_delalloc(inode, start, end,
+			NULL, EXTENT_LOCKED | EXTENT_DELALLOC,
+			PAGE_UNLOCK | PAGE_START_WRITEBACK);
+	btrfs_submit_compressed_write(ordered,
+			    async_extent->pages,	/* compressed_pages */
+			    async_extent->nr_pages,
+			    async_chunk->write_flags, true);
+	*alloc_hint = ins.objectid + ins.offset;
+done:
+	if (async_chunk->blkcg_css)
+		kthread_associate_blkcg(NULL);
+	kfree(async_extent);
+	return;
+
+out_free_reserve:
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
+out_free:
+	mapping_set_error(inode->vfs_inode.i_mapping, -EIO);
+	extent_clear_unlock_delalloc(inode, start, end,
+				     NULL, EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_DELALLOC_NEW |
+				     EXTENT_DEFRAG | EXTENT_DO_ACCOUNTING,
+				     PAGE_UNLOCK | PAGE_START_WRITEBACK |
+				     PAGE_END_WRITEBACK);
+	free_async_extent_pages(async_extent);
+	if (async_chunk->blkcg_css)
+		kthread_associate_blkcg(NULL);
+	btrfs_debug(fs_info,
+"async extent submission failed root=%lld inode=%llu start=%llu len=%llu ret=%d",
+		    root->root_key.objectid, btrfs_ino(inode), start,
+		    async_extent->ram_size, ret);
+	kfree(async_extent);
+}
+
+static u64 get_extent_allocation_hint(struct btrfs_inode *inode, u64 start,
+				      u64 num_bytes)
+{
+	struct extent_map_tree *em_tree = &inode->extent_tree;
+	struct extent_map *em;
+	u64 alloc_hint = 0;
+
+	read_lock(&em_tree->lock);
+	em = search_extent_mapping(em_tree, start, num_bytes);
+	if (em) {
+		/*
+		 * if block start isn't an actual block number then find the
+		 * first block in this inode and use that as a hint.  If that
+		 * block is also bogus then just don't worry about it.
+		 */
+		if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
+			free_extent_map(em);
+			em = search_extent_mapping(em_tree, 0, 0);
+			if (em && em->block_start < EXTENT_MAP_LAST_BYTE)
+				alloc_hint = em->block_start;
+			if (em)
+				free_extent_map(em);
+		} else {
+			alloc_hint = em->block_start;
+			free_extent_map(em);
+		}
+	}
+	read_unlock(&em_tree->lock);
+
+	return alloc_hint;
+}
+
+/*
+ * when extent_io.c finds a delayed allocation range in the file,
+ * the call backs end up in this code.  The basic idea is to
+ * allocate extents on disk for the range, and create ordered data structs
+ * in ram to track those extents.
+ *
+ * locked_page is the page that writepage had locked already.  We use
+ * it to make sure we don't do extra locks or unlocks.
+ *
+ * When this function fails, it unlocks all pages except @locked_page.
+ *
+ * When this function successfully creates an inline extent, it returns 1 and
+ * unlocks all pages including locked_page and starts I/O on them.
+ * (In reality inline extents are limited to a single page, so locked_page is
+ * the only page handled anyway).
+ *
+ * When this function succeed and creates a normal extent, the page locking
+ * status depends on the passed in flags:
+ *
+ * - If @keep_locked is set, all pages are kept locked.
+ * - Else all pages except for @locked_page are unlocked.
+ *
+ * When a failure happens in the second or later iteration of the
+ * while-loop, the ordered extents created in previous iterations are kept
+ * intact. So, the caller must clean them up by calling
+ * btrfs_cleanup_ordered_extents(). See btrfs_run_delalloc_range() for
+ * example.
+ */
+static noinline int cow_file_range(struct btrfs_inode *inode,
+				   struct page *locked_page, u64 start, u64 end,
+				   u64 *done_offset,
+				   bool keep_locked, bool no_inline)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	u64 alloc_hint = 0;
+	u64 orig_start = start;
+	u64 num_bytes;
+	unsigned long ram_size;
+	u64 cur_alloc_size = 0;
+	u64 min_alloc_size;
+	u64 blocksize = fs_info->sectorsize;
+	struct btrfs_key ins;
+	struct extent_map *em;
+	unsigned clear_bits;
+	unsigned long page_ops;
+	bool extent_reserved = false;
+	int ret = 0;
+
+	if (btrfs_is_free_space_inode(inode)) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	num_bytes = ALIGN(end - start + 1, blocksize);
+	num_bytes = max(blocksize,  num_bytes);
+	ASSERT(num_bytes <= btrfs_super_total_bytes(fs_info->super_copy));
+
+	inode_should_defrag(inode, start, end, num_bytes, SZ_64K);
+
+	/*
+	 * Due to the page size limit, for subpage we can only trigger the
+	 * writeback for the dirty sectors of page, that means data writeback
+	 * is doing more writeback than what we want.
+	 *
+	 * This is especially unexpected for some call sites like fallocate,
+	 * where we only increase i_size after everything is done.
+	 * This means we can trigger inline extent even if we didn't want to.
+	 * So here we skip inline extent creation completely.
+	 */
+	if (start == 0 && fs_info->sectorsize == PAGE_SIZE && !no_inline) {
+		u64 actual_end = min_t(u64, i_size_read(&inode->vfs_inode),
+				       end + 1);
+
+		/* lets try to make an inline extent */
+		ret = cow_file_range_inline(inode, actual_end, 0,
+					    BTRFS_COMPRESS_NONE, NULL, false);
+		if (ret == 0) {
+			/*
+			 * We use DO_ACCOUNTING here because we need the
+			 * delalloc_release_metadata to be run _after_ we drop
+			 * our outstanding extent for clearing delalloc for this
+			 * range.
+			 */
+			extent_clear_unlock_delalloc(inode, start, end,
+				     locked_page,
+				     EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
+				     EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
+				     PAGE_START_WRITEBACK | PAGE_END_WRITEBACK);
+			/*
+			 * locked_page is locked by the caller of
+			 * writepage_delalloc(), not locked by
+			 * __process_pages_contig().
+			 *
+			 * We can't let __process_pages_contig() to unlock it,
+			 * as it doesn't have any subpage::writers recorded.
+			 *
+			 * Here we manually unlock the page, since the caller
+			 * can't determine if it's an inline extent or a
+			 * compressed extent.
+			 */
+			unlock_page(locked_page);
+			ret = 1;
+			goto done;
+		} else if (ret < 0) {
+			goto out_unlock;
+		}
+	}
+
+	alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
+
+	/*
+	 * Relocation relies on the relocated extents to have exactly the same
+	 * size as the original extents. Normally writeback for relocation data
+	 * extents follows a NOCOW path because relocation preallocates the
+	 * extents. However, due to an operation such as scrub turning a block
+	 * group to RO mode, it may fallback to COW mode, so we must make sure
+	 * an extent allocated during COW has exactly the requested size and can
+	 * not be split into smaller extents, otherwise relocation breaks and
+	 * fails during the stage where it updates the bytenr of file extent
+	 * items.
+	 */
+	if (btrfs_is_data_reloc_root(root))
+		min_alloc_size = num_bytes;
+	else
+		min_alloc_size = fs_info->sectorsize;
+
+	while (num_bytes > 0) {
+		struct btrfs_ordered_extent *ordered;
+
+		cur_alloc_size = num_bytes;
+		ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
+					   min_alloc_size, 0, alloc_hint,
+					   &ins, 1, 1);
+		if (ret == -EAGAIN) {
+			/*
+			 * btrfs_reserve_extent only returns -EAGAIN for zoned
+			 * file systems, which is an indication that there are
+			 * no active zones to allocate from at the moment.
+			 *
+			 * If this is the first loop iteration, wait for at
+			 * least one zone to finish before retrying the
+			 * allocation.  Otherwise ask the caller to write out
+			 * the already allocated blocks before coming back to
+			 * us, or return -ENOSPC if it can't handle retries.
+			 */
+			ASSERT(btrfs_is_zoned(fs_info));
+			if (start == orig_start) {
+				wait_on_bit_io(&inode->root->fs_info->flags,
+					       BTRFS_FS_NEED_ZONE_FINISH,
+					       TASK_UNINTERRUPTIBLE);
+				continue;
+			}
+			if (done_offset) {
+				*done_offset = start - 1;
+				return 0;
+			}
+			ret = -ENOSPC;
+		}
+		if (ret < 0)
+			goto out_unlock;
+		cur_alloc_size = ins.offset;
+		extent_reserved = true;
+
+		ram_size = ins.offset;
+		em = create_io_em(inode, start, ins.offset, /* len */
+				  start, /* orig_start */
+				  ins.objectid, /* block_start */
+				  ins.offset, /* block_len */
+				  ins.offset, /* orig_block_len */
+				  ram_size, /* ram_bytes */
+				  BTRFS_COMPRESS_NONE, /* compress_type */
+				  BTRFS_ORDERED_REGULAR /* type */);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			goto out_reserve;
+		}
+		free_extent_map(em);
+
+		ordered = btrfs_alloc_ordered_extent(inode, start, ram_size,
+					ram_size, ins.objectid, cur_alloc_size,
+					0, 1 << BTRFS_ORDERED_REGULAR,
+					BTRFS_COMPRESS_NONE);
+		if (IS_ERR(ordered)) {
+			ret = PTR_ERR(ordered);
+			goto out_drop_extent_cache;
+		}
+
+		if (btrfs_is_data_reloc_root(root)) {
+			ret = btrfs_reloc_clone_csums(ordered);
+
+			/*
+			 * Only drop cache here, and process as normal.
+			 *
+			 * We must not allow extent_clear_unlock_delalloc()
+			 * at out_unlock label to free meta of this ordered
+			 * extent, as its meta should be freed by
+			 * btrfs_finish_ordered_io().
+			 *
+			 * So we must continue until @start is increased to
+			 * skip current ordered extent.
+			 */
+			if (ret)
+				btrfs_drop_extent_map_range(inode, start,
+							    start + ram_size - 1,
+							    false);
+		}
+		btrfs_put_ordered_extent(ordered);
+
+		btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+
+		/*
+		 * We're not doing compressed IO, don't unlock the first page
+		 * (which the caller expects to stay locked), don't clear any
+		 * dirty bits and don't set any writeback bits
+		 *
+		 * Do set the Ordered (Private2) bit so we know this page was
+		 * properly setup for writepage.
+		 */
+		page_ops = (keep_locked ? 0 : PAGE_UNLOCK);
+		page_ops |= PAGE_SET_ORDERED;
+
+		extent_clear_unlock_delalloc(inode, start, start + ram_size - 1,
+					     locked_page,
+					     EXTENT_LOCKED | EXTENT_DELALLOC,
+					     page_ops);
+		if (num_bytes < cur_alloc_size)
+			num_bytes = 0;
+		else
+			num_bytes -= cur_alloc_size;
+		alloc_hint = ins.objectid + ins.offset;
+		start += cur_alloc_size;
+		extent_reserved = false;
+
+		/*
+		 * btrfs_reloc_clone_csums() error, since start is increased
+		 * extent_clear_unlock_delalloc() at out_unlock label won't
+		 * free metadata of current ordered extent, we're OK to exit.
+		 */
+		if (ret)
+			goto out_unlock;
+	}
+done:
+	if (done_offset)
+		*done_offset = end;
+	return ret;
+
+out_drop_extent_cache:
+	btrfs_drop_extent_map_range(inode, start, start + ram_size - 1, false);
+out_reserve:
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
+out_unlock:
+	/*
+	 * Now, we have three regions to clean up:
+	 *
+	 * |-------(1)----|---(2)---|-------------(3)----------|
+	 * `- orig_start  `- start  `- start + cur_alloc_size  `- end
+	 *
+	 * We process each region below.
+	 */
+
+	clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+		EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV;
+	page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK;
+
+	/*
+	 * For the range (1). We have already instantiated the ordered extents
+	 * for this region. They are cleaned up by
+	 * btrfs_cleanup_ordered_extents() in e.g,
+	 * btrfs_run_delalloc_range(). EXTENT_LOCKED | EXTENT_DELALLOC are
+	 * already cleared in the above loop. And, EXTENT_DELALLOC_NEW |
+	 * EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV are handled by the cleanup
+	 * function.
+	 *
+	 * However, in case of @keep_locked, we still need to unlock the pages
+	 * (except @locked_page) to ensure all the pages are unlocked.
+	 */
+	if (keep_locked && orig_start < start) {
+		if (!locked_page)
+			mapping_set_error(inode->vfs_inode.i_mapping, ret);
+		extent_clear_unlock_delalloc(inode, orig_start, start - 1,
+					     locked_page, 0, page_ops);
+	}
+
+	/*
+	 * For the range (2). If we reserved an extent for our delalloc range
+	 * (or a subrange) and failed to create the respective ordered extent,
+	 * then it means that when we reserved the extent we decremented the
+	 * extent's size from the data space_info's bytes_may_use counter and
+	 * incremented the space_info's bytes_reserved counter by the same
+	 * amount. We must make sure extent_clear_unlock_delalloc() does not try
+	 * to decrement again the data space_info's bytes_may_use counter,
+	 * therefore we do not pass it the flag EXTENT_CLEAR_DATA_RESV.
+	 */
+	if (extent_reserved) {
+		extent_clear_unlock_delalloc(inode, start,
+					     start + cur_alloc_size - 1,
+					     locked_page,
+					     clear_bits,
+					     page_ops);
+		start += cur_alloc_size;
+	}
+
+	/*
+	 * For the range (3). We never touched the region. In addition to the
+	 * clear_bits above, we add EXTENT_CLEAR_DATA_RESV to release the data
+	 * space_info's bytes_may_use counter, reserved in
+	 * btrfs_check_data_free_space().
+	 */
+	if (start < end) {
+		clear_bits |= EXTENT_CLEAR_DATA_RESV;
+		extent_clear_unlock_delalloc(inode, start, end, locked_page,
+					     clear_bits, page_ops);
+	}
+	return ret;
+}
+
+/*
+ * Phase two of compressed writeback.  This is the ordered portion of the code,
+ * which only gets called in the order the work was queued.  We walk all the
+ * async extents created by compress_file_range and send them down to the disk.
+ */
+static noinline void submit_compressed_extents(struct btrfs_work *work)
+{
+	struct async_chunk *async_chunk = container_of(work, struct async_chunk,
+						     work);
+	struct btrfs_fs_info *fs_info = btrfs_work_owner(work);
+	struct async_extent *async_extent;
+	unsigned long nr_pages;
+	u64 alloc_hint = 0;
+
+	nr_pages = (async_chunk->end - async_chunk->start + PAGE_SIZE) >>
+		PAGE_SHIFT;
+
+	while (!list_empty(&async_chunk->extents)) {
+		async_extent = list_entry(async_chunk->extents.next,
+					  struct async_extent, list);
+		list_del(&async_extent->list);
+		submit_one_async_extent(async_chunk, async_extent, &alloc_hint);
+	}
+
+	/* atomic_sub_return implies a barrier */
+	if (atomic_sub_return(nr_pages, &fs_info->async_delalloc_pages) <
+	    5 * SZ_1M)
+		cond_wake_up_nomb(&fs_info->async_submit_wait);
+}
+
+static noinline void async_cow_free(struct btrfs_work *work)
+{
+	struct async_chunk *async_chunk;
+	struct async_cow *async_cow;
+
+	async_chunk = container_of(work, struct async_chunk, work);
+	btrfs_add_delayed_iput(async_chunk->inode);
+	if (async_chunk->blkcg_css)
+		css_put(async_chunk->blkcg_css);
+
+	async_cow = async_chunk->async_cow;
+	if (atomic_dec_and_test(&async_cow->num_chunks))
+		kvfree(async_cow);
+}
+
+static bool run_delalloc_compressed(struct btrfs_inode *inode,
+				    struct page *locked_page, u64 start,
+				    u64 end, struct writeback_control *wbc)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct cgroup_subsys_state *blkcg_css = wbc_blkcg_css(wbc);
+	struct async_cow *ctx;
+	struct async_chunk *async_chunk;
+	unsigned long nr_pages;
+	u64 num_chunks = DIV_ROUND_UP(end - start, SZ_512K);
+	int i;
+	unsigned nofs_flag;
+	const blk_opf_t write_flags = wbc_to_write_flags(wbc);
+
+	nofs_flag = memalloc_nofs_save();
+	ctx = kvmalloc(struct_size(ctx, chunks, num_chunks), GFP_KERNEL);
+	memalloc_nofs_restore(nofs_flag);
+	if (!ctx)
+		return false;
+
+	unlock_extent(&inode->io_tree, start, end, NULL);
+	set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &inode->runtime_flags);
+
+	async_chunk = ctx->chunks;
+	atomic_set(&ctx->num_chunks, num_chunks);
+
+	for (i = 0; i < num_chunks; i++) {
+		u64 cur_end = min(end, start + SZ_512K - 1);
+
+		/*
+		 * igrab is called higher up in the call chain, take only the
+		 * lightweight reference for the callback lifetime
+		 */
+		ihold(&inode->vfs_inode);
+		async_chunk[i].async_cow = ctx;
+		async_chunk[i].inode = inode;
+		async_chunk[i].start = start;
+		async_chunk[i].end = cur_end;
+		async_chunk[i].write_flags = write_flags;
+		INIT_LIST_HEAD(&async_chunk[i].extents);
+
+		/*
+		 * The locked_page comes all the way from writepage and its
+		 * the original page we were actually given.  As we spread
+		 * this large delalloc region across multiple async_chunk
+		 * structs, only the first struct needs a pointer to locked_page
+		 *
+		 * This way we don't need racey decisions about who is supposed
+		 * to unlock it.
+		 */
+		if (locked_page) {
+			/*
+			 * Depending on the compressibility, the pages might or
+			 * might not go through async.  We want all of them to
+			 * be accounted against wbc once.  Let's do it here
+			 * before the paths diverge.  wbc accounting is used
+			 * only for foreign writeback detection and doesn't
+			 * need full accuracy.  Just account the whole thing
+			 * against the first page.
+			 */
+			wbc_account_cgroup_owner(wbc, locked_page,
+						 cur_end - start);
+			async_chunk[i].locked_page = locked_page;
+			locked_page = NULL;
+		} else {
+			async_chunk[i].locked_page = NULL;
+		}
+
+		if (blkcg_css != blkcg_root_css) {
+			css_get(blkcg_css);
+			async_chunk[i].blkcg_css = blkcg_css;
+			async_chunk[i].write_flags |= REQ_BTRFS_CGROUP_PUNT;
+		} else {
+			async_chunk[i].blkcg_css = NULL;
+		}
+
+		btrfs_init_work(&async_chunk[i].work, compress_file_range,
+				submit_compressed_extents, async_cow_free);
+
+		nr_pages = DIV_ROUND_UP(cur_end - start, PAGE_SIZE);
+		atomic_add(nr_pages, &fs_info->async_delalloc_pages);
+
+		btrfs_queue_work(fs_info->delalloc_workers, &async_chunk[i].work);
+
+		start = cur_end + 1;
+	}
+	return true;
+}
+
+/*
+ * Run the delalloc range from start to end, and write back any dirty pages
+ * covered by the range.
+ */
+static noinline int run_delalloc_cow(struct btrfs_inode *inode,
+				     struct page *locked_page, u64 start,
+				     u64 end, struct writeback_control *wbc,
+				     bool pages_dirty)
+{
+	u64 done_offset = end;
+	int ret;
+
+	while (start <= end) {
+		ret = cow_file_range(inode, locked_page, start, end, &done_offset,
+				     true, false);
+		if (ret)
+			return ret;
+		extent_write_locked_range(&inode->vfs_inode, locked_page, start,
+					  done_offset, wbc, pages_dirty);
+		start = done_offset + 1;
+	}
+
+	return 1;
+}
+
+static noinline int csum_exist_in_range(struct btrfs_fs_info *fs_info,
+					u64 bytenr, u64 num_bytes, bool nowait)
+{
+	struct btrfs_root *csum_root = btrfs_csum_root(fs_info, bytenr);
+	struct btrfs_ordered_sum *sums;
+	int ret;
+	LIST_HEAD(list);
+
+	ret = btrfs_lookup_csums_list(csum_root, bytenr, bytenr + num_bytes - 1,
+				      &list, 0, nowait);
+	if (ret == 0 && list_empty(&list))
+		return 0;
+
+	while (!list_empty(&list)) {
+		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
+		list_del(&sums->list);
+		kfree(sums);
+	}
+	if (ret < 0)
+		return ret;
+	return 1;
+}
+
+static int fallback_to_cow(struct btrfs_inode *inode, struct page *locked_page,
+			   const u64 start, const u64 end)
+{
+	const bool is_space_ino = btrfs_is_free_space_inode(inode);
+	const bool is_reloc_ino = btrfs_is_data_reloc_root(inode->root);
+	const u64 range_bytes = end + 1 - start;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	u64 range_start = start;
+	u64 count;
+	int ret;
+
+	/*
+	 * If EXTENT_NORESERVE is set it means that when the buffered write was
+	 * made we had not enough available data space and therefore we did not
+	 * reserve data space for it, since we though we could do NOCOW for the
+	 * respective file range (either there is prealloc extent or the inode
+	 * has the NOCOW bit set).
+	 *
+	 * However when we need to fallback to COW mode (because for example the
+	 * block group for the corresponding extent was turned to RO mode by a
+	 * scrub or relocation) we need to do the following:
+	 *
+	 * 1) We increment the bytes_may_use counter of the data space info.
+	 *    If COW succeeds, it allocates a new data extent and after doing
+	 *    that it decrements the space info's bytes_may_use counter and
+	 *    increments its bytes_reserved counter by the same amount (we do
+	 *    this at btrfs_add_reserved_bytes()). So we need to increment the
+	 *    bytes_may_use counter to compensate (when space is reserved at
+	 *    buffered write time, the bytes_may_use counter is incremented);
+	 *
+	 * 2) We clear the EXTENT_NORESERVE bit from the range. We do this so
+	 *    that if the COW path fails for any reason, it decrements (through
+	 *    extent_clear_unlock_delalloc()) the bytes_may_use counter of the
+	 *    data space info, which we incremented in the step above.
+	 *
+	 * If we need to fallback to cow and the inode corresponds to a free
+	 * space cache inode or an inode of the data relocation tree, we must
+	 * also increment bytes_may_use of the data space_info for the same
+	 * reason. Space caches and relocated data extents always get a prealloc
+	 * extent for them, however scrub or balance may have set the block
+	 * group that contains that extent to RO mode and therefore force COW
+	 * when starting writeback.
+	 */
+	count = count_range_bits(io_tree, &range_start, end, range_bytes,
+				 EXTENT_NORESERVE, 0, NULL);
+	if (count > 0 || is_space_ino || is_reloc_ino) {
+		u64 bytes = count;
+		struct btrfs_fs_info *fs_info = inode->root->fs_info;
+		struct btrfs_space_info *sinfo = fs_info->data_sinfo;
+
+		if (is_space_ino || is_reloc_ino)
+			bytes = range_bytes;
+
+		spin_lock(&sinfo->lock);
+		btrfs_space_info_update_bytes_may_use(fs_info, sinfo, bytes);
+		spin_unlock(&sinfo->lock);
+
+		if (count > 0)
+			clear_extent_bit(io_tree, start, end, EXTENT_NORESERVE,
+					 NULL);
+	}
+
+	/*
+	 * Don't try to create inline extents, as a mix of inline extent that
+	 * is written out and unlocked directly and a normal NOCOW extent
+	 * doesn't work.
+	 */
+	ret = cow_file_range(inode, locked_page, start, end, NULL, false, true);
+	ASSERT(ret != 1);
+	return ret;
+}
+
+struct can_nocow_file_extent_args {
+	/* Input fields. */
+
+	/* Start file offset of the range we want to NOCOW. */
+	u64 start;
+	/* End file offset (inclusive) of the range we want to NOCOW. */
+	u64 end;
+	bool writeback_path;
+	bool strict;
+	/*
+	 * Free the path passed to can_nocow_file_extent() once it's not needed
+	 * anymore.
+	 */
+	bool free_path;
+
+	/* Output fields. Only set when can_nocow_file_extent() returns 1. */
+
+	u64 disk_bytenr;
+	u64 disk_num_bytes;
+	u64 extent_offset;
+	/* Number of bytes that can be written to in NOCOW mode. */
+	u64 num_bytes;
+};
+
+/*
+ * Check if we can NOCOW the file extent that the path points to.
+ * This function may return with the path released, so the caller should check
+ * if path->nodes[0] is NULL or not if it needs to use the path afterwards.
+ *
+ * Returns: < 0 on error
+ *            0 if we can not NOCOW
+ *            1 if we can NOCOW
+ */
+static int can_nocow_file_extent(struct btrfs_path *path,
+				 struct btrfs_key *key,
+				 struct btrfs_inode *inode,
+				 struct can_nocow_file_extent_args *args)
+{
+	const bool is_freespace_inode = btrfs_is_free_space_inode(inode);
+	struct extent_buffer *leaf = path->nodes[0];
+	struct btrfs_root *root = inode->root;
+	struct btrfs_file_extent_item *fi;
+	u64 extent_end;
+	u8 extent_type;
+	int can_nocow = 0;
+	int ret = 0;
+	bool nowait = path->nowait;
+
+	fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
+	extent_type = btrfs_file_extent_type(leaf, fi);
+
+	if (extent_type == BTRFS_FILE_EXTENT_INLINE)
+		goto out;
+
+	/* Can't access these fields unless we know it's not an inline extent. */
+	args->disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+	args->disk_num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
+	args->extent_offset = btrfs_file_extent_offset(leaf, fi);
+
+	if (!(inode->flags & BTRFS_INODE_NODATACOW) &&
+	    extent_type == BTRFS_FILE_EXTENT_REG)
+		goto out;
+
+	/*
+	 * If the extent was created before the generation where the last snapshot
+	 * for its subvolume was created, then this implies the extent is shared,
+	 * hence we must COW.
+	 */
+	if (!args->strict &&
+	    btrfs_file_extent_generation(leaf, fi) <=
+	    btrfs_root_last_snapshot(&root->root_item))
+		goto out;
+
+	/* An explicit hole, must COW. */
+	if (args->disk_bytenr == 0)
+		goto out;
+
+	/* Compressed/encrypted/encoded extents must be COWed. */
+	if (btrfs_file_extent_compression(leaf, fi) ||
+	    btrfs_file_extent_encryption(leaf, fi) ||
+	    btrfs_file_extent_other_encoding(leaf, fi))
+		goto out;
+
+	extent_end = btrfs_file_extent_end(path);
+
+	/*
+	 * The following checks can be expensive, as they need to take other
+	 * locks and do btree or rbtree searches, so release the path to avoid
+	 * blocking other tasks for too long.
+	 */
+	btrfs_release_path(path);
+
+	ret = btrfs_cross_ref_exist(root, btrfs_ino(inode),
+				    key->offset - args->extent_offset,
+				    args->disk_bytenr, args->strict, path);
+	WARN_ON_ONCE(ret > 0 && is_freespace_inode);
+	if (ret != 0)
+		goto out;
+
+	if (args->free_path) {
+		/*
+		 * We don't need the path anymore, plus through the
+		 * csum_exist_in_range() call below we will end up allocating
+		 * another path. So free the path to avoid unnecessary extra
+		 * memory usage.
+		 */
+		btrfs_free_path(path);
+		path = NULL;
+	}
+
+	/* If there are pending snapshots for this root, we must COW. */
+	if (args->writeback_path && !is_freespace_inode &&
+	    atomic_read(&root->snapshot_force_cow))
+		goto out;
+
+	args->disk_bytenr += args->extent_offset;
+	args->disk_bytenr += args->start - key->offset;
+	args->num_bytes = min(args->end + 1, extent_end) - args->start;
+
+	/*
+	 * Force COW if csums exist in the range. This ensures that csums for a
+	 * given extent are either valid or do not exist.
+	 */
+	ret = csum_exist_in_range(root->fs_info, args->disk_bytenr, args->num_bytes,
+				  nowait);
+	WARN_ON_ONCE(ret > 0 && is_freespace_inode);
+	if (ret != 0)
+		goto out;
+
+	can_nocow = 1;
+ out:
+	if (args->free_path && path)
+		btrfs_free_path(path);
+
+	return ret < 0 ? ret : can_nocow;
+}
+
+/*
+ * when nowcow writeback call back.  This checks for snapshots or COW copies
+ * of the extents that exist in the file, and COWs the file as required.
+ *
+ * If no cow copies or snapshots exist, we write directly to the existing
+ * blocks on disk
+ */
+static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
+				       struct page *locked_page,
+				       const u64 start, const u64 end)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_path *path;
+	u64 cow_start = (u64)-1;
+	u64 cur_offset = start;
+	int ret;
+	bool check_prev = true;
+	u64 ino = btrfs_ino(inode);
+	struct can_nocow_file_extent_args nocow_args = { 0 };
+
+	/*
+	 * Normally on a zoned device we're only doing COW writes, but in case
+	 * of relocation on a zoned filesystem serializes I/O so that we're only
+	 * writing sequentially and can end up here as well.
+	 */
+	ASSERT(!btrfs_is_zoned(fs_info) || btrfs_is_data_reloc_root(root));
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	nocow_args.end = end;
+	nocow_args.writeback_path = true;
+
+	while (1) {
+		struct btrfs_block_group *nocow_bg = NULL;
+		struct btrfs_ordered_extent *ordered;
+		struct btrfs_key found_key;
+		struct btrfs_file_extent_item *fi;
+		struct extent_buffer *leaf;
+		u64 extent_end;
+		u64 ram_bytes;
+		u64 nocow_end;
+		int extent_type;
+		bool is_prealloc;
+
+		ret = btrfs_lookup_file_extent(NULL, root, path, ino,
+					       cur_offset, 0);
+		if (ret < 0)
+			goto error;
+
+		/*
+		 * If there is no extent for our range when doing the initial
+		 * search, then go back to the previous slot as it will be the
+		 * one containing the search offset
+		 */
+		if (ret > 0 && path->slots[0] > 0 && check_prev) {
+			leaf = path->nodes[0];
+			btrfs_item_key_to_cpu(leaf, &found_key,
+					      path->slots[0] - 1);
+			if (found_key.objectid == ino &&
+			    found_key.type == BTRFS_EXTENT_DATA_KEY)
+				path->slots[0]--;
+		}
+		check_prev = false;
+next_slot:
+		/* Go to next leaf if we have exhausted the current one */
+		leaf = path->nodes[0];
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto error;
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		/* Didn't find anything for our INO */
+		if (found_key.objectid > ino)
+			break;
+		/*
+		 * Keep searching until we find an EXTENT_ITEM or there are no
+		 * more extents for this inode
+		 */
+		if (WARN_ON_ONCE(found_key.objectid < ino) ||
+		    found_key.type < BTRFS_EXTENT_DATA_KEY) {
+			path->slots[0]++;
+			goto next_slot;
+		}
+
+		/* Found key is not EXTENT_DATA_KEY or starts after req range */
+		if (found_key.type > BTRFS_EXTENT_DATA_KEY ||
+		    found_key.offset > end)
+			break;
+
+		/*
+		 * If the found extent starts after requested offset, then
+		 * adjust extent_end to be right before this extent begins
+		 */
+		if (found_key.offset > cur_offset) {
+			extent_end = found_key.offset;
+			extent_type = 0;
+			goto must_cow;
+		}
+
+		/*
+		 * Found extent which begins before our range and potentially
+		 * intersect it
+		 */
+		fi = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_file_extent_item);
+		extent_type = btrfs_file_extent_type(leaf, fi);
+		/* If this is triggered then we have a memory corruption. */
+		ASSERT(extent_type < BTRFS_NR_FILE_EXTENT_TYPES);
+		if (WARN_ON(extent_type >= BTRFS_NR_FILE_EXTENT_TYPES)) {
+			ret = -EUCLEAN;
+			goto error;
+		}
+		ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
+		extent_end = btrfs_file_extent_end(path);
+
+		/*
+		 * If the extent we got ends before our current offset, skip to
+		 * the next extent.
+		 */
+		if (extent_end <= cur_offset) {
+			path->slots[0]++;
+			goto next_slot;
+		}
+
+		nocow_args.start = cur_offset;
+		ret = can_nocow_file_extent(path, &found_key, inode, &nocow_args);
+		if (ret < 0)
+			goto error;
+		if (ret == 0)
+			goto must_cow;
+
+		ret = 0;
+		nocow_bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr);
+		if (!nocow_bg) {
+must_cow:
+			/*
+			 * If we can't perform NOCOW writeback for the range,
+			 * then record the beginning of the range that needs to
+			 * be COWed.  It will be written out before the next
+			 * NOCOW range if we find one, or when exiting this
+			 * loop.
+			 */
+			if (cow_start == (u64)-1)
+				cow_start = cur_offset;
+			cur_offset = extent_end;
+			if (cur_offset > end)
+				break;
+			if (!path->nodes[0])
+				continue;
+			path->slots[0]++;
+			goto next_slot;
+		}
+
+		/*
+		 * COW range from cow_start to found_key.offset - 1. As the key
+		 * will contain the beginning of the first extent that can be
+		 * NOCOW, following one which needs to be COW'ed
+		 */
+		if (cow_start != (u64)-1) {
+			ret = fallback_to_cow(inode, locked_page,
+					      cow_start, found_key.offset - 1);
+			cow_start = (u64)-1;
+			if (ret) {
+				btrfs_dec_nocow_writers(nocow_bg);
+				goto error;
+			}
+		}
+
+		nocow_end = cur_offset + nocow_args.num_bytes - 1;
+		is_prealloc = extent_type == BTRFS_FILE_EXTENT_PREALLOC;
+		if (is_prealloc) {
+			u64 orig_start = found_key.offset - nocow_args.extent_offset;
+			struct extent_map *em;
+
+			em = create_io_em(inode, cur_offset, nocow_args.num_bytes,
+					  orig_start,
+					  nocow_args.disk_bytenr, /* block_start */
+					  nocow_args.num_bytes, /* block_len */
+					  nocow_args.disk_num_bytes, /* orig_block_len */
+					  ram_bytes, BTRFS_COMPRESS_NONE,
+					  BTRFS_ORDERED_PREALLOC);
+			if (IS_ERR(em)) {
+				btrfs_dec_nocow_writers(nocow_bg);
+				ret = PTR_ERR(em);
+				goto error;
+			}
+			free_extent_map(em);
+		}
+
+		ordered = btrfs_alloc_ordered_extent(inode, cur_offset,
+				nocow_args.num_bytes, nocow_args.num_bytes,
+				nocow_args.disk_bytenr, nocow_args.num_bytes, 0,
+				is_prealloc
+				? (1 << BTRFS_ORDERED_PREALLOC)
+				: (1 << BTRFS_ORDERED_NOCOW),
+				BTRFS_COMPRESS_NONE);
+		btrfs_dec_nocow_writers(nocow_bg);
+		if (IS_ERR(ordered)) {
+			if (is_prealloc) {
+				btrfs_drop_extent_map_range(inode, cur_offset,
+							    nocow_end, false);
+			}
+			ret = PTR_ERR(ordered);
+			goto error;
+		}
+
+		if (btrfs_is_data_reloc_root(root))
+			/*
+			 * Error handled later, as we must prevent
+			 * extent_clear_unlock_delalloc() in error handler
+			 * from freeing metadata of created ordered extent.
+			 */
+			ret = btrfs_reloc_clone_csums(ordered);
+		btrfs_put_ordered_extent(ordered);
+
+		extent_clear_unlock_delalloc(inode, cur_offset, nocow_end,
+					     locked_page, EXTENT_LOCKED |
+					     EXTENT_DELALLOC |
+					     EXTENT_CLEAR_DATA_RESV,
+					     PAGE_UNLOCK | PAGE_SET_ORDERED);
+
+		cur_offset = extent_end;
+
+		/*
+		 * btrfs_reloc_clone_csums() error, now we're OK to call error
+		 * handler, as metadata for created ordered extent will only
+		 * be freed by btrfs_finish_ordered_io().
+		 */
+		if (ret)
+			goto error;
+		if (cur_offset > end)
+			break;
+	}
+	btrfs_release_path(path);
+
+	if (cur_offset <= end && cow_start == (u64)-1)
+		cow_start = cur_offset;
+
+	if (cow_start != (u64)-1) {
+		cur_offset = end;
+		ret = fallback_to_cow(inode, locked_page, cow_start, end);
+		cow_start = (u64)-1;
+		if (ret)
+			goto error;
+	}
+
+	btrfs_free_path(path);
+	return 0;
+
+error:
+	/*
+	 * If an error happened while a COW region is outstanding, cur_offset
+	 * needs to be reset to cow_start to ensure the COW region is unlocked
+	 * as well.
+	 */
+	if (cow_start != (u64)-1)
+		cur_offset = cow_start;
+	if (cur_offset < end)
+		extent_clear_unlock_delalloc(inode, cur_offset, end,
+					     locked_page, EXTENT_LOCKED |
+					     EXTENT_DELALLOC | EXTENT_DEFRAG |
+					     EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
+					     PAGE_START_WRITEBACK |
+					     PAGE_END_WRITEBACK);
+	btrfs_free_path(path);
+	return ret;
+}
+
+static bool should_nocow(struct btrfs_inode *inode, u64 start, u64 end)
+{
+	if (inode->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)) {
+		if (inode->defrag_bytes &&
+		    test_range_bit(&inode->io_tree, start, end, EXTENT_DEFRAG,
+				   0, NULL))
+			return false;
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Function to process delayed allocation (create CoW) for ranges which are
+ * being touched for the first time.
+ */
+int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page,
+			     u64 start, u64 end, struct writeback_control *wbc)
+{
+	const bool zoned = btrfs_is_zoned(inode->root->fs_info);
+	int ret;
+
+	/*
+	 * The range must cover part of the @locked_page, or a return of 1
+	 * can confuse the caller.
+	 */
+	ASSERT(!(end <= page_offset(locked_page) ||
+		 start >= page_offset(locked_page) + PAGE_SIZE));
+
+	if (should_nocow(inode, start, end)) {
+		ret = run_delalloc_nocow(inode, locked_page, start, end);
+		goto out;
+	}
+
+	if (btrfs_inode_can_compress(inode) &&
+	    inode_need_compress(inode, start, end) &&
+	    run_delalloc_compressed(inode, locked_page, start, end, wbc))
+		return 1;
+
+	if (zoned)
+		ret = run_delalloc_cow(inode, locked_page, start, end, wbc,
+				       true);
+	else
+		ret = cow_file_range(inode, locked_page, start, end, NULL,
+				     false, false);
+
+out:
+	if (ret < 0)
+		btrfs_cleanup_ordered_extents(inode, locked_page, start,
+					      end - start + 1);
+	return ret;
+}
+
+void btrfs_split_delalloc_extent(struct btrfs_inode *inode,
+				 struct extent_state *orig, u64 split)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 size;
+
+	/* not delalloc, ignore it */
+	if (!(orig->state & EXTENT_DELALLOC))
+		return;
+
+	size = orig->end - orig->start + 1;
+	if (size > fs_info->max_extent_size) {
+		u32 num_extents;
+		u64 new_size;
+
+		/*
+		 * See the explanation in btrfs_merge_delalloc_extent, the same
+		 * applies here, just in reverse.
+		 */
+		new_size = orig->end - split + 1;
+		num_extents = count_max_extents(fs_info, new_size);
+		new_size = split - orig->start;
+		num_extents += count_max_extents(fs_info, new_size);
+		if (count_max_extents(fs_info, size) >= num_extents)
+			return;
+	}
+
+	spin_lock(&inode->lock);
+	btrfs_mod_outstanding_extents(inode, 1);
+	spin_unlock(&inode->lock);
+}
+
+/*
+ * Handle merged delayed allocation extents so we can keep track of new extents
+ * that are just merged onto old extents, such as when we are doing sequential
+ * writes, so we can properly account for the metadata space we'll need.
+ */
+void btrfs_merge_delalloc_extent(struct btrfs_inode *inode, struct extent_state *new,
+				 struct extent_state *other)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 new_size, old_size;
+	u32 num_extents;
+
+	/* not delalloc, ignore it */
+	if (!(other->state & EXTENT_DELALLOC))
+		return;
+
+	if (new->start > other->start)
+		new_size = new->end - other->start + 1;
+	else
+		new_size = other->end - new->start + 1;
+
+	/* we're not bigger than the max, unreserve the space and go */
+	if (new_size <= fs_info->max_extent_size) {
+		spin_lock(&inode->lock);
+		btrfs_mod_outstanding_extents(inode, -1);
+		spin_unlock(&inode->lock);
+		return;
+	}
+
+	/*
+	 * We have to add up either side to figure out how many extents were
+	 * accounted for before we merged into one big extent.  If the number of
+	 * extents we accounted for is <= the amount we need for the new range
+	 * then we can return, otherwise drop.  Think of it like this
+	 *
+	 * [ 4k][MAX_SIZE]
+	 *
+	 * So we've grown the extent by a MAX_SIZE extent, this would mean we
+	 * need 2 outstanding extents, on one side we have 1 and the other side
+	 * we have 1 so they are == and we can return.  But in this case
+	 *
+	 * [MAX_SIZE+4k][MAX_SIZE+4k]
+	 *
+	 * Each range on their own accounts for 2 extents, but merged together
+	 * they are only 3 extents worth of accounting, so we need to drop in
+	 * this case.
+	 */
+	old_size = other->end - other->start + 1;
+	num_extents = count_max_extents(fs_info, old_size);
+	old_size = new->end - new->start + 1;
+	num_extents += count_max_extents(fs_info, old_size);
+	if (count_max_extents(fs_info, new_size) >= num_extents)
+		return;
+
+	spin_lock(&inode->lock);
+	btrfs_mod_outstanding_extents(inode, -1);
+	spin_unlock(&inode->lock);
+}
+
+static void btrfs_add_delalloc_inodes(struct btrfs_root *root,
+				      struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	spin_lock(&root->delalloc_lock);
+	if (list_empty(&inode->delalloc_inodes)) {
+		list_add_tail(&inode->delalloc_inodes, &root->delalloc_inodes);
+		set_bit(BTRFS_INODE_IN_DELALLOC_LIST, &inode->runtime_flags);
+		root->nr_delalloc_inodes++;
+		if (root->nr_delalloc_inodes == 1) {
+			spin_lock(&fs_info->delalloc_root_lock);
+			BUG_ON(!list_empty(&root->delalloc_root));
+			list_add_tail(&root->delalloc_root,
+				      &fs_info->delalloc_roots);
+			spin_unlock(&fs_info->delalloc_root_lock);
+		}
+	}
+	spin_unlock(&root->delalloc_lock);
+}
+
+void __btrfs_del_delalloc_inode(struct btrfs_root *root,
+				struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	if (!list_empty(&inode->delalloc_inodes)) {
+		list_del_init(&inode->delalloc_inodes);
+		clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+			  &inode->runtime_flags);
+		root->nr_delalloc_inodes--;
+		if (!root->nr_delalloc_inodes) {
+			ASSERT(list_empty(&root->delalloc_inodes));
+			spin_lock(&fs_info->delalloc_root_lock);
+			BUG_ON(list_empty(&root->delalloc_root));
+			list_del_init(&root->delalloc_root);
+			spin_unlock(&fs_info->delalloc_root_lock);
+		}
+	}
+}
+
+static void btrfs_del_delalloc_inode(struct btrfs_root *root,
+				     struct btrfs_inode *inode)
+{
+	spin_lock(&root->delalloc_lock);
+	__btrfs_del_delalloc_inode(root, inode);
+	spin_unlock(&root->delalloc_lock);
+}
+
+/*
+ * Properly track delayed allocation bytes in the inode and to maintain the
+ * list of inodes that have pending delalloc work to be done.
+ */
+void btrfs_set_delalloc_extent(struct btrfs_inode *inode, struct extent_state *state,
+			       u32 bits)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	if ((bits & EXTENT_DEFRAG) && !(bits & EXTENT_DELALLOC))
+		WARN_ON(1);
+	/*
+	 * set_bit and clear bit hooks normally require _irqsave/restore
+	 * but in this case, we are only testing for the DELALLOC
+	 * bit, which is only set or cleared with irqs on
+	 */
+	if (!(state->state & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
+		struct btrfs_root *root = inode->root;
+		u64 len = state->end + 1 - state->start;
+		u32 num_extents = count_max_extents(fs_info, len);
+		bool do_list = !btrfs_is_free_space_inode(inode);
+
+		spin_lock(&inode->lock);
+		btrfs_mod_outstanding_extents(inode, num_extents);
+		spin_unlock(&inode->lock);
+
+		/* For sanity tests */
+		if (btrfs_is_testing(fs_info))
+			return;
+
+		percpu_counter_add_batch(&fs_info->delalloc_bytes, len,
+					 fs_info->delalloc_batch);
+		spin_lock(&inode->lock);
+		inode->delalloc_bytes += len;
+		if (bits & EXTENT_DEFRAG)
+			inode->defrag_bytes += len;
+		if (do_list && !test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+					 &inode->runtime_flags))
+			btrfs_add_delalloc_inodes(root, inode);
+		spin_unlock(&inode->lock);
+	}
+
+	if (!(state->state & EXTENT_DELALLOC_NEW) &&
+	    (bits & EXTENT_DELALLOC_NEW)) {
+		spin_lock(&inode->lock);
+		inode->new_delalloc_bytes += state->end + 1 - state->start;
+		spin_unlock(&inode->lock);
+	}
+}
+
+/*
+ * Once a range is no longer delalloc this function ensures that proper
+ * accounting happens.
+ */
+void btrfs_clear_delalloc_extent(struct btrfs_inode *inode,
+				 struct extent_state *state, u32 bits)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 len = state->end + 1 - state->start;
+	u32 num_extents = count_max_extents(fs_info, len);
+
+	if ((state->state & EXTENT_DEFRAG) && (bits & EXTENT_DEFRAG)) {
+		spin_lock(&inode->lock);
+		inode->defrag_bytes -= len;
+		spin_unlock(&inode->lock);
+	}
+
+	/*
+	 * set_bit and clear bit hooks normally require _irqsave/restore
+	 * but in this case, we are only testing for the DELALLOC
+	 * bit, which is only set or cleared with irqs on
+	 */
+	if ((state->state & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
+		struct btrfs_root *root = inode->root;
+		bool do_list = !btrfs_is_free_space_inode(inode);
+
+		spin_lock(&inode->lock);
+		btrfs_mod_outstanding_extents(inode, -num_extents);
+		spin_unlock(&inode->lock);
+
+		/*
+		 * We don't reserve metadata space for space cache inodes so we
+		 * don't need to call delalloc_release_metadata if there is an
+		 * error.
+		 */
+		if (bits & EXTENT_CLEAR_META_RESV &&
+		    root != fs_info->tree_root)
+			btrfs_delalloc_release_metadata(inode, len, false);
+
+		/* For sanity tests. */
+		if (btrfs_is_testing(fs_info))
+			return;
+
+		if (!btrfs_is_data_reloc_root(root) &&
+		    do_list && !(state->state & EXTENT_NORESERVE) &&
+		    (bits & EXTENT_CLEAR_DATA_RESV))
+			btrfs_free_reserved_data_space_noquota(fs_info, len);
+
+		percpu_counter_add_batch(&fs_info->delalloc_bytes, -len,
+					 fs_info->delalloc_batch);
+		spin_lock(&inode->lock);
+		inode->delalloc_bytes -= len;
+		if (do_list && inode->delalloc_bytes == 0 &&
+		    test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+					&inode->runtime_flags))
+			btrfs_del_delalloc_inode(root, inode);
+		spin_unlock(&inode->lock);
+	}
+
+	if ((state->state & EXTENT_DELALLOC_NEW) &&
+	    (bits & EXTENT_DELALLOC_NEW)) {
+		spin_lock(&inode->lock);
+		ASSERT(inode->new_delalloc_bytes >= len);
+		inode->new_delalloc_bytes -= len;
+		if (bits & EXTENT_ADD_INODE_BYTES)
+			inode_add_bytes(&inode->vfs_inode, len);
+		spin_unlock(&inode->lock);
+	}
+}
+
+static int btrfs_extract_ordered_extent(struct btrfs_bio *bbio,
+					struct btrfs_ordered_extent *ordered)
+{
+	u64 start = (u64)bbio->bio.bi_iter.bi_sector << SECTOR_SHIFT;
+	u64 len = bbio->bio.bi_iter.bi_size;
+	struct btrfs_ordered_extent *new;
+	int ret;
+
+	/* Must always be called for the beginning of an ordered extent. */
+	if (WARN_ON_ONCE(start != ordered->disk_bytenr))
+		return -EINVAL;
+
+	/* No need to split if the ordered extent covers the entire bio. */
+	if (ordered->disk_num_bytes == len) {
+		refcount_inc(&ordered->refs);
+		bbio->ordered = ordered;
+		return 0;
+	}
+
+	/*
+	 * Don't split the extent_map for NOCOW extents, as we're writing into
+	 * a pre-existing one.
+	 */
+	if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags)) {
+		ret = split_extent_map(bbio->inode, bbio->file_offset,
+				       ordered->num_bytes, len,
+				       ordered->disk_bytenr);
+		if (ret)
+			return ret;
+	}
+
+	new = btrfs_split_ordered_extent(ordered, len);
+	if (IS_ERR(new))
+		return PTR_ERR(new);
+	bbio->ordered = new;
+	return 0;
+}
+
+/*
+ * given a list of ordered sums record them in the inode.  This happens
+ * at IO completion time based on sums calculated at bio submission time.
+ */
+static int add_pending_csums(struct btrfs_trans_handle *trans,
+			     struct list_head *list)
+{
+	struct btrfs_ordered_sum *sum;
+	struct btrfs_root *csum_root = NULL;
+	int ret;
+
+	list_for_each_entry(sum, list, list) {
+		trans->adding_csums = true;
+		if (!csum_root)
+			csum_root = btrfs_csum_root(trans->fs_info,
+						    sum->logical);
+		ret = btrfs_csum_file_blocks(trans, csum_root, sum);
+		trans->adding_csums = false;
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode,
+					 const u64 start,
+					 const u64 len,
+					 struct extent_state **cached_state)
+{
+	u64 search_start = start;
+	const u64 end = start + len - 1;
+
+	while (search_start < end) {
+		const u64 search_len = end - search_start + 1;
+		struct extent_map *em;
+		u64 em_len;
+		int ret = 0;
+
+		em = btrfs_get_extent(inode, NULL, 0, search_start, search_len);
+		if (IS_ERR(em))
+			return PTR_ERR(em);
+
+		if (em->block_start != EXTENT_MAP_HOLE)
+			goto next;
+
+		em_len = em->len;
+		if (em->start < search_start)
+			em_len -= search_start - em->start;
+		if (em_len > search_len)
+			em_len = search_len;
+
+		ret = set_extent_bit(&inode->io_tree, search_start,
+				     search_start + em_len - 1,
+				     EXTENT_DELALLOC_NEW, cached_state);
+next:
+		search_start = extent_map_end(em);
+		free_extent_map(em);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+int btrfs_set_extent_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
+			      unsigned int extra_bits,
+			      struct extent_state **cached_state)
+{
+	WARN_ON(PAGE_ALIGNED(end));
+
+	if (start >= i_size_read(&inode->vfs_inode) &&
+	    !(inode->flags & BTRFS_INODE_PREALLOC)) {
+		/*
+		 * There can't be any extents following eof in this case so just
+		 * set the delalloc new bit for the range directly.
+		 */
+		extra_bits |= EXTENT_DELALLOC_NEW;
+	} else {
+		int ret;
+
+		ret = btrfs_find_new_delalloc_bytes(inode, start,
+						    end + 1 - start,
+						    cached_state);
+		if (ret)
+			return ret;
+	}
+
+	return set_extent_bit(&inode->io_tree, start, end,
+			      EXTENT_DELALLOC | extra_bits, cached_state);
+}
+
+/* see btrfs_writepage_start_hook for details on why this is required */
+struct btrfs_writepage_fixup {
+	struct page *page;
+	struct btrfs_inode *inode;
+	struct btrfs_work work;
+};
+
+static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
+{
+	struct btrfs_writepage_fixup *fixup =
+		container_of(work, struct btrfs_writepage_fixup, work);
+	struct btrfs_ordered_extent *ordered;
+	struct extent_state *cached_state = NULL;
+	struct extent_changeset *data_reserved = NULL;
+	struct page *page = fixup->page;
+	struct btrfs_inode *inode = fixup->inode;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 page_start = page_offset(page);
+	u64 page_end = page_offset(page) + PAGE_SIZE - 1;
+	int ret = 0;
+	bool free_delalloc_space = true;
+
+	/*
+	 * This is similar to page_mkwrite, we need to reserve the space before
+	 * we take the page lock.
+	 */
+	ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
+					   PAGE_SIZE);
+again:
+	lock_page(page);
+
+	/*
+	 * Before we queued this fixup, we took a reference on the page.
+	 * page->mapping may go NULL, but it shouldn't be moved to a different
+	 * address space.
+	 */
+	if (!page->mapping || !PageDirty(page) || !PageChecked(page)) {
+		/*
+		 * Unfortunately this is a little tricky, either
+		 *
+		 * 1) We got here and our page had already been dealt with and
+		 *    we reserved our space, thus ret == 0, so we need to just
+		 *    drop our space reservation and bail.  This can happen the
+		 *    first time we come into the fixup worker, or could happen
+		 *    while waiting for the ordered extent.
+		 * 2) Our page was already dealt with, but we happened to get an
+		 *    ENOSPC above from the btrfs_delalloc_reserve_space.  In
+		 *    this case we obviously don't have anything to release, but
+		 *    because the page was already dealt with we don't want to
+		 *    mark the page with an error, so make sure we're resetting
+		 *    ret to 0.  This is why we have this check _before_ the ret
+		 *    check, because we do not want to have a surprise ENOSPC
+		 *    when the page was already properly dealt with.
+		 */
+		if (!ret) {
+			btrfs_delalloc_release_extents(inode, PAGE_SIZE);
+			btrfs_delalloc_release_space(inode, data_reserved,
+						     page_start, PAGE_SIZE,
+						     true);
+		}
+		ret = 0;
+		goto out_page;
+	}
+
+	/*
+	 * We can't mess with the page state unless it is locked, so now that
+	 * it is locked bail if we failed to make our space reservation.
+	 */
+	if (ret)
+		goto out_page;
+
+	lock_extent(&inode->io_tree, page_start, page_end, &cached_state);
+
+	/* already ordered? We're done */
+	if (PageOrdered(page))
+		goto out_reserved;
+
+	ordered = btrfs_lookup_ordered_range(inode, page_start, PAGE_SIZE);
+	if (ordered) {
+		unlock_extent(&inode->io_tree, page_start, page_end,
+			      &cached_state);
+		unlock_page(page);
+		btrfs_start_ordered_extent(ordered);
+		btrfs_put_ordered_extent(ordered);
+		goto again;
+	}
+
+	ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
+					&cached_state);
+	if (ret)
+		goto out_reserved;
+
+	/*
+	 * Everything went as planned, we're now the owner of a dirty page with
+	 * delayed allocation bits set and space reserved for our COW
+	 * destination.
+	 *
+	 * The page was dirty when we started, nothing should have cleaned it.
+	 */
+	BUG_ON(!PageDirty(page));
+	free_delalloc_space = false;
+out_reserved:
+	btrfs_delalloc_release_extents(inode, PAGE_SIZE);
+	if (free_delalloc_space)
+		btrfs_delalloc_release_space(inode, data_reserved, page_start,
+					     PAGE_SIZE, true);
+	unlock_extent(&inode->io_tree, page_start, page_end, &cached_state);
+out_page:
+	if (ret) {
+		/*
+		 * We hit ENOSPC or other errors.  Update the mapping and page
+		 * to reflect the errors and clean the page.
+		 */
+		mapping_set_error(page->mapping, ret);
+		btrfs_mark_ordered_io_finished(inode, page, page_start,
+					       PAGE_SIZE, !ret);
+		clear_page_dirty_for_io(page);
+	}
+	btrfs_page_clear_checked(fs_info, page, page_start, PAGE_SIZE);
+	unlock_page(page);
+	put_page(page);
+	kfree(fixup);
+	extent_changeset_free(data_reserved);
+	/*
+	 * As a precaution, do a delayed iput in case it would be the last iput
+	 * that could need flushing space. Recursing back to fixup worker would
+	 * deadlock.
+	 */
+	btrfs_add_delayed_iput(inode);
+}
+
+/*
+ * There are a few paths in the higher layers of the kernel that directly
+ * set the page dirty bit without asking the filesystem if it is a
+ * good idea.  This causes problems because we want to make sure COW
+ * properly happens and the data=ordered rules are followed.
+ *
+ * In our case any range that doesn't have the ORDERED bit set
+ * hasn't been properly setup for IO.  We kick off an async process
+ * to fix it up.  The async helper will wait for ordered extents, set
+ * the delalloc bit and make it safe to write the page.
+ */
+int btrfs_writepage_cow_fixup(struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_writepage_fixup *fixup;
+
+	/* This page has ordered extent covering it already */
+	if (PageOrdered(page))
+		return 0;
+
+	/*
+	 * PageChecked is set below when we create a fixup worker for this page,
+	 * don't try to create another one if we're already PageChecked()
+	 *
+	 * The extent_io writepage code will redirty the page if we send back
+	 * EAGAIN.
+	 */
+	if (PageChecked(page))
+		return -EAGAIN;
+
+	fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
+	if (!fixup)
+		return -EAGAIN;
+
+	/*
+	 * We are already holding a reference to this inode from
+	 * write_cache_pages.  We need to hold it because the space reservation
+	 * takes place outside of the page lock, and we can't trust
+	 * page->mapping outside of the page lock.
+	 */
+	ihold(inode);
+	btrfs_page_set_checked(fs_info, page, page_offset(page), PAGE_SIZE);
+	get_page(page);
+	btrfs_init_work(&fixup->work, btrfs_writepage_fixup_worker, NULL, NULL);
+	fixup->page = page;
+	fixup->inode = BTRFS_I(inode);
+	btrfs_queue_work(fs_info->fixup_workers, &fixup->work);
+
+	return -EAGAIN;
+}
+
+static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
+				       struct btrfs_inode *inode, u64 file_pos,
+				       struct btrfs_file_extent_item *stack_fi,
+				       const bool update_inode_bytes,
+				       u64 qgroup_reserved)
+{
+	struct btrfs_root *root = inode->root;
+	const u64 sectorsize = root->fs_info->sectorsize;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_key ins;
+	u64 disk_num_bytes = btrfs_stack_file_extent_disk_num_bytes(stack_fi);
+	u64 disk_bytenr = btrfs_stack_file_extent_disk_bytenr(stack_fi);
+	u64 offset = btrfs_stack_file_extent_offset(stack_fi);
+	u64 num_bytes = btrfs_stack_file_extent_num_bytes(stack_fi);
+	u64 ram_bytes = btrfs_stack_file_extent_ram_bytes(stack_fi);
+	struct btrfs_drop_extents_args drop_args = { 0 };
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	/*
+	 * we may be replacing one extent in the tree with another.
+	 * The new extent is pinned in the extent map, and we don't want
+	 * to drop it from the cache until it is completely in the btree.
+	 *
+	 * So, tell btrfs_drop_extents to leave this extent in the cache.
+	 * the caller is expected to unpin it and allow it to be merged
+	 * with the others.
+	 */
+	drop_args.path = path;
+	drop_args.start = file_pos;
+	drop_args.end = file_pos + num_bytes;
+	drop_args.replace_extent = true;
+	drop_args.extent_item_size = sizeof(*stack_fi);
+	ret = btrfs_drop_extents(trans, root, inode, &drop_args);
+	if (ret)
+		goto out;
+
+	if (!drop_args.extent_inserted) {
+		ins.objectid = btrfs_ino(inode);
+		ins.offset = file_pos;
+		ins.type = BTRFS_EXTENT_DATA_KEY;
+
+		ret = btrfs_insert_empty_item(trans, root, path, &ins,
+					      sizeof(*stack_fi));
+		if (ret)
+			goto out;
+	}
+	leaf = path->nodes[0];
+	btrfs_set_stack_file_extent_generation(stack_fi, trans->transid);
+	write_extent_buffer(leaf, stack_fi,
+			btrfs_item_ptr_offset(leaf, path->slots[0]),
+			sizeof(struct btrfs_file_extent_item));
+
+	btrfs_mark_buffer_dirty(trans, leaf);
+	btrfs_release_path(path);
+
+	/*
+	 * If we dropped an inline extent here, we know the range where it is
+	 * was not marked with the EXTENT_DELALLOC_NEW bit, so we update the
+	 * number of bytes only for that range containing the inline extent.
+	 * The remaining of the range will be processed when clearning the
+	 * EXTENT_DELALLOC_BIT bit through the ordered extent completion.
+	 */
+	if (file_pos == 0 && !IS_ALIGNED(drop_args.bytes_found, sectorsize)) {
+		u64 inline_size = round_down(drop_args.bytes_found, sectorsize);
+
+		inline_size = drop_args.bytes_found - inline_size;
+		btrfs_update_inode_bytes(inode, sectorsize, inline_size);
+		drop_args.bytes_found -= inline_size;
+		num_bytes -= sectorsize;
+	}
+
+	if (update_inode_bytes)
+		btrfs_update_inode_bytes(inode, num_bytes, drop_args.bytes_found);
+
+	ins.objectid = disk_bytenr;
+	ins.offset = disk_num_bytes;
+	ins.type = BTRFS_EXTENT_ITEM_KEY;
+
+	ret = btrfs_inode_set_file_extent_range(inode, file_pos, ram_bytes);
+	if (ret)
+		goto out;
+
+	ret = btrfs_alloc_reserved_file_extent(trans, root, btrfs_ino(inode),
+					       file_pos - offset,
+					       qgroup_reserved, &ins);
+out:
+	btrfs_free_path(path);
+
+	return ret;
+}
+
+static void btrfs_release_delalloc_bytes(struct btrfs_fs_info *fs_info,
+					 u64 start, u64 len)
+{
+	struct btrfs_block_group *cache;
+
+	cache = btrfs_lookup_block_group(fs_info, start);
+	ASSERT(cache);
+
+	spin_lock(&cache->lock);
+	cache->delalloc_bytes -= len;
+	spin_unlock(&cache->lock);
+
+	btrfs_put_block_group(cache);
+}
+
+static int insert_ordered_extent_file_extent(struct btrfs_trans_handle *trans,
+					     struct btrfs_ordered_extent *oe)
+{
+	struct btrfs_file_extent_item stack_fi;
+	bool update_inode_bytes;
+	u64 num_bytes = oe->num_bytes;
+	u64 ram_bytes = oe->ram_bytes;
+
+	memset(&stack_fi, 0, sizeof(stack_fi));
+	btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_REG);
+	btrfs_set_stack_file_extent_disk_bytenr(&stack_fi, oe->disk_bytenr);
+	btrfs_set_stack_file_extent_disk_num_bytes(&stack_fi,
+						   oe->disk_num_bytes);
+	btrfs_set_stack_file_extent_offset(&stack_fi, oe->offset);
+	if (test_bit(BTRFS_ORDERED_TRUNCATED, &oe->flags)) {
+		num_bytes = oe->truncated_len;
+		ram_bytes = num_bytes;
+	}
+	btrfs_set_stack_file_extent_num_bytes(&stack_fi, num_bytes);
+	btrfs_set_stack_file_extent_ram_bytes(&stack_fi, ram_bytes);
+	btrfs_set_stack_file_extent_compression(&stack_fi, oe->compress_type);
+	/* Encryption and other encoding is reserved and all 0 */
+
+	/*
+	 * For delalloc, when completing an ordered extent we update the inode's
+	 * bytes when clearing the range in the inode's io tree, so pass false
+	 * as the argument 'update_inode_bytes' to insert_reserved_file_extent(),
+	 * except if the ordered extent was truncated.
+	 */
+	update_inode_bytes = test_bit(BTRFS_ORDERED_DIRECT, &oe->flags) ||
+			     test_bit(BTRFS_ORDERED_ENCODED, &oe->flags) ||
+			     test_bit(BTRFS_ORDERED_TRUNCATED, &oe->flags);
+
+	return insert_reserved_file_extent(trans, BTRFS_I(oe->inode),
+					   oe->file_offset, &stack_fi,
+					   update_inode_bytes, oe->qgroup_rsv);
+}
+
+/*
+ * As ordered data IO finishes, this gets called so we can finish
+ * an ordered extent if the range of bytes in the file it covers are
+ * fully written.
+ */
+int btrfs_finish_one_ordered(struct btrfs_ordered_extent *ordered_extent)
+{
+	struct btrfs_inode *inode = BTRFS_I(ordered_extent->inode);
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans = NULL;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct extent_state *cached_state = NULL;
+	u64 start, end;
+	int compress_type = 0;
+	int ret = 0;
+	u64 logical_len = ordered_extent->num_bytes;
+	bool freespace_inode;
+	bool truncated = false;
+	bool clear_reserved_extent = true;
+	unsigned int clear_bits = EXTENT_DEFRAG;
+
+	start = ordered_extent->file_offset;
+	end = start + ordered_extent->num_bytes - 1;
+
+	if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
+	    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags) &&
+	    !test_bit(BTRFS_ORDERED_DIRECT, &ordered_extent->flags) &&
+	    !test_bit(BTRFS_ORDERED_ENCODED, &ordered_extent->flags))
+		clear_bits |= EXTENT_DELALLOC_NEW;
+
+	freespace_inode = btrfs_is_free_space_inode(inode);
+	if (!freespace_inode)
+		btrfs_lockdep_acquire(fs_info, btrfs_ordered_extent);
+
+	if (test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags)) {
+		ret = -EIO;
+		goto out;
+	}
+
+	if (btrfs_is_zoned(fs_info))
+		btrfs_zone_finish_endio(fs_info, ordered_extent->disk_bytenr,
+					ordered_extent->disk_num_bytes);
+
+	if (test_bit(BTRFS_ORDERED_TRUNCATED, &ordered_extent->flags)) {
+		truncated = true;
+		logical_len = ordered_extent->truncated_len;
+		/* Truncated the entire extent, don't bother adding */
+		if (!logical_len)
+			goto out;
+	}
+
+	if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {
+		BUG_ON(!list_empty(&ordered_extent->list)); /* Logic error */
+
+		btrfs_inode_safe_disk_i_size_write(inode, 0);
+		if (freespace_inode)
+			trans = btrfs_join_transaction_spacecache(root);
+		else
+			trans = btrfs_join_transaction(root);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			trans = NULL;
+			goto out;
+		}
+		trans->block_rsv = &inode->block_rsv;
+		ret = btrfs_update_inode_fallback(trans, root, inode);
+		if (ret) /* -ENOMEM or corruption */
+			btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	clear_bits |= EXTENT_LOCKED;
+	lock_extent(io_tree, start, end, &cached_state);
+
+	if (freespace_inode)
+		trans = btrfs_join_transaction_spacecache(root);
+	else
+		trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		trans = NULL;
+		goto out;
+	}
+
+	trans->block_rsv = &inode->block_rsv;
+
+	if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags))
+		compress_type = ordered_extent->compress_type;
+	if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
+		BUG_ON(compress_type);
+		ret = btrfs_mark_extent_written(trans, inode,
+						ordered_extent->file_offset,
+						ordered_extent->file_offset +
+						logical_len);
+		btrfs_zoned_release_data_reloc_bg(fs_info, ordered_extent->disk_bytenr,
+						  ordered_extent->disk_num_bytes);
+	} else {
+		BUG_ON(root == fs_info->tree_root);
+		ret = insert_ordered_extent_file_extent(trans, ordered_extent);
+		if (!ret) {
+			clear_reserved_extent = false;
+			btrfs_release_delalloc_bytes(fs_info,
+						ordered_extent->disk_bytenr,
+						ordered_extent->disk_num_bytes);
+		}
+	}
+	unpin_extent_cache(&inode->extent_tree, ordered_extent->file_offset,
+			   ordered_extent->num_bytes, trans->transid);
+	if (ret < 0) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	ret = add_pending_csums(trans, &ordered_extent->list);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	/*
+	 * If this is a new delalloc range, clear its new delalloc flag to
+	 * update the inode's number of bytes. This needs to be done first
+	 * before updating the inode item.
+	 */
+	if ((clear_bits & EXTENT_DELALLOC_NEW) &&
+	    !test_bit(BTRFS_ORDERED_TRUNCATED, &ordered_extent->flags))
+		clear_extent_bit(&inode->io_tree, start, end,
+				 EXTENT_DELALLOC_NEW | EXTENT_ADD_INODE_BYTES,
+				 &cached_state);
+
+	btrfs_inode_safe_disk_i_size_write(inode, 0);
+	ret = btrfs_update_inode_fallback(trans, root, inode);
+	if (ret) { /* -ENOMEM or corruption */
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+	ret = 0;
+out:
+	clear_extent_bit(&inode->io_tree, start, end, clear_bits,
+			 &cached_state);
+
+	if (trans)
+		btrfs_end_transaction(trans);
+
+	if (ret || truncated) {
+		u64 unwritten_start = start;
+
+		/*
+		 * If we failed to finish this ordered extent for any reason we
+		 * need to make sure BTRFS_ORDERED_IOERR is set on the ordered
+		 * extent, and mark the inode with the error if it wasn't
+		 * already set.  Any error during writeback would have already
+		 * set the mapping error, so we need to set it if we're the ones
+		 * marking this ordered extent as failed.
+		 */
+		if (ret && !test_and_set_bit(BTRFS_ORDERED_IOERR,
+					     &ordered_extent->flags))
+			mapping_set_error(ordered_extent->inode->i_mapping, -EIO);
+
+		if (truncated)
+			unwritten_start += logical_len;
+		clear_extent_uptodate(io_tree, unwritten_start, end, NULL);
+
+		/* Drop extent maps for the part of the extent we didn't write. */
+		btrfs_drop_extent_map_range(inode, unwritten_start, end, false);
+
+		/*
+		 * If the ordered extent had an IOERR or something else went
+		 * wrong we need to return the space for this ordered extent
+		 * back to the allocator.  We only free the extent in the
+		 * truncated case if we didn't write out the extent at all.
+		 *
+		 * If we made it past insert_reserved_file_extent before we
+		 * errored out then we don't need to do this as the accounting
+		 * has already been done.
+		 */
+		if ((ret || !logical_len) &&
+		    clear_reserved_extent &&
+		    !test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
+		    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
+			/*
+			 * Discard the range before returning it back to the
+			 * free space pool
+			 */
+			if (ret && btrfs_test_opt(fs_info, DISCARD_SYNC))
+				btrfs_discard_extent(fs_info,
+						ordered_extent->disk_bytenr,
+						ordered_extent->disk_num_bytes,
+						NULL);
+			btrfs_free_reserved_extent(fs_info,
+					ordered_extent->disk_bytenr,
+					ordered_extent->disk_num_bytes, 1);
+			/*
+			 * Actually free the qgroup rsv which was released when
+			 * the ordered extent was created.
+			 */
+			btrfs_qgroup_free_refroot(fs_info, inode->root->root_key.objectid,
+						  ordered_extent->qgroup_rsv,
+						  BTRFS_QGROUP_RSV_DATA);
+		}
+	}
+
+	/*
+	 * This needs to be done to make sure anybody waiting knows we are done
+	 * updating everything for this ordered extent.
+	 */
+	btrfs_remove_ordered_extent(inode, ordered_extent);
+
+	/* once for us */
+	btrfs_put_ordered_extent(ordered_extent);
+	/* once for the tree */
+	btrfs_put_ordered_extent(ordered_extent);
+
+	return ret;
+}
+
+int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered)
+{
+	if (btrfs_is_zoned(btrfs_sb(ordered->inode->i_sb)) &&
+	    !test_bit(BTRFS_ORDERED_IOERR, &ordered->flags))
+		btrfs_finish_ordered_zoned(ordered);
+	return btrfs_finish_one_ordered(ordered);
+}
+
+/*
+ * Verify the checksum for a single sector without any extra action that depend
+ * on the type of I/O.
+ */
+int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page,
+			    u32 pgoff, u8 *csum, const u8 * const csum_expected)
+{
+	SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
+	char *kaddr;
+
+	ASSERT(pgoff + fs_info->sectorsize <= PAGE_SIZE);
+
+	shash->tfm = fs_info->csum_shash;
+
+	kaddr = kmap_local_page(page) + pgoff;
+	crypto_shash_digest(shash, kaddr, fs_info->sectorsize, csum);
+	kunmap_local(kaddr);
+
+	if (memcmp(csum, csum_expected, fs_info->csum_size))
+		return -EIO;
+	return 0;
+}
+
+/*
+ * Verify the checksum of a single data sector.
+ *
+ * @bbio:	btrfs_io_bio which contains the csum
+ * @dev:	device the sector is on
+ * @bio_offset:	offset to the beginning of the bio (in bytes)
+ * @bv:		bio_vec to check
+ *
+ * Check if the checksum on a data block is valid.  When a checksum mismatch is
+ * detected, report the error and fill the corrupted range with zero.
+ *
+ * Return %true if the sector is ok or had no checksum to start with, else %false.
+ */
+bool btrfs_data_csum_ok(struct btrfs_bio *bbio, struct btrfs_device *dev,
+			u32 bio_offset, struct bio_vec *bv)
+{
+	struct btrfs_inode *inode = bbio->inode;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 file_offset = bbio->file_offset + bio_offset;
+	u64 end = file_offset + bv->bv_len - 1;
+	u8 *csum_expected;
+	u8 csum[BTRFS_CSUM_SIZE];
+
+	ASSERT(bv->bv_len == fs_info->sectorsize);
+
+	if (!bbio->csum)
+		return true;
+
+	if (btrfs_is_data_reloc_root(inode->root) &&
+	    test_range_bit(&inode->io_tree, file_offset, end, EXTENT_NODATASUM,
+			   1, NULL)) {
+		/* Skip the range without csum for data reloc inode */
+		clear_extent_bits(&inode->io_tree, file_offset, end,
+				  EXTENT_NODATASUM);
+		return true;
+	}
+
+	csum_expected = bbio->csum + (bio_offset >> fs_info->sectorsize_bits) *
+				fs_info->csum_size;
+	if (btrfs_check_sector_csum(fs_info, bv->bv_page, bv->bv_offset, csum,
+				    csum_expected))
+		goto zeroit;
+	return true;
+
+zeroit:
+	btrfs_print_data_csum_error(inode, file_offset, csum, csum_expected,
+				    bbio->mirror_num);
+	if (dev)
+		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_CORRUPTION_ERRS);
+	memzero_bvec(bv);
+	return false;
+}
+
+/*
+ * btrfs_add_delayed_iput - perform a delayed iput on @inode
+ *
+ * @inode: The inode we want to perform iput on
+ *
+ * This function uses the generic vfs_inode::i_count to track whether we should
+ * just decrement it (in case it's > 1) or if this is the last iput then link
+ * the inode to the delayed iput machinery. Delayed iputs are processed at
+ * transaction commit time/superblock commit/cleaner kthread.
+ */
+void btrfs_add_delayed_iput(struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	unsigned long flags;
+
+	if (atomic_add_unless(&inode->vfs_inode.i_count, -1, 1))
+		return;
+
+	atomic_inc(&fs_info->nr_delayed_iputs);
+	/*
+	 * Need to be irq safe here because we can be called from either an irq
+	 * context (see bio.c and btrfs_put_ordered_extent()) or a non-irq
+	 * context.
+	 */
+	spin_lock_irqsave(&fs_info->delayed_iput_lock, flags);
+	ASSERT(list_empty(&inode->delayed_iput));
+	list_add_tail(&inode->delayed_iput, &fs_info->delayed_iputs);
+	spin_unlock_irqrestore(&fs_info->delayed_iput_lock, flags);
+	if (!test_bit(BTRFS_FS_CLEANER_RUNNING, &fs_info->flags))
+		wake_up_process(fs_info->cleaner_kthread);
+}
+
+static void run_delayed_iput_locked(struct btrfs_fs_info *fs_info,
+				    struct btrfs_inode *inode)
+{
+	list_del_init(&inode->delayed_iput);
+	spin_unlock_irq(&fs_info->delayed_iput_lock);
+	iput(&inode->vfs_inode);
+	if (atomic_dec_and_test(&fs_info->nr_delayed_iputs))
+		wake_up(&fs_info->delayed_iputs_wait);
+	spin_lock_irq(&fs_info->delayed_iput_lock);
+}
+
+static void btrfs_run_delayed_iput(struct btrfs_fs_info *fs_info,
+				   struct btrfs_inode *inode)
+{
+	if (!list_empty(&inode->delayed_iput)) {
+		spin_lock_irq(&fs_info->delayed_iput_lock);
+		if (!list_empty(&inode->delayed_iput))
+			run_delayed_iput_locked(fs_info, inode);
+		spin_unlock_irq(&fs_info->delayed_iput_lock);
+	}
+}
+
+void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info)
+{
+	/*
+	 * btrfs_put_ordered_extent() can run in irq context (see bio.c), which
+	 * calls btrfs_add_delayed_iput() and that needs to lock
+	 * fs_info->delayed_iput_lock. So we need to disable irqs here to
+	 * prevent a deadlock.
+	 */
+	spin_lock_irq(&fs_info->delayed_iput_lock);
+	while (!list_empty(&fs_info->delayed_iputs)) {
+		struct btrfs_inode *inode;
+
+		inode = list_first_entry(&fs_info->delayed_iputs,
+				struct btrfs_inode, delayed_iput);
+		run_delayed_iput_locked(fs_info, inode);
+		if (need_resched()) {
+			spin_unlock_irq(&fs_info->delayed_iput_lock);
+			cond_resched();
+			spin_lock_irq(&fs_info->delayed_iput_lock);
+		}
+	}
+	spin_unlock_irq(&fs_info->delayed_iput_lock);
+}
+
+/*
+ * Wait for flushing all delayed iputs
+ *
+ * @fs_info:  the filesystem
+ *
+ * This will wait on any delayed iputs that are currently running with KILLABLE
+ * set.  Once they are all done running we will return, unless we are killed in
+ * which case we return EINTR. This helps in user operations like fallocate etc
+ * that might get blocked on the iputs.
+ *
+ * Return EINTR if we were killed, 0 if nothing's pending
+ */
+int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info)
+{
+	int ret = wait_event_killable(fs_info->delayed_iputs_wait,
+			atomic_read(&fs_info->nr_delayed_iputs) == 0);
+	if (ret)
+		return -EINTR;
+	return 0;
+}
+
+/*
+ * This creates an orphan entry for the given inode in case something goes wrong
+ * in the middle of an unlink.
+ */
+int btrfs_orphan_add(struct btrfs_trans_handle *trans,
+		     struct btrfs_inode *inode)
+{
+	int ret;
+
+	ret = btrfs_insert_orphan_item(trans, inode->root, btrfs_ino(inode));
+	if (ret && ret != -EEXIST) {
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * We have done the delete so we can go ahead and remove the orphan item for
+ * this particular inode.
+ */
+static int btrfs_orphan_del(struct btrfs_trans_handle *trans,
+			    struct btrfs_inode *inode)
+{
+	return btrfs_del_orphan_item(trans, inode->root, btrfs_ino(inode));
+}
+
+/*
+ * this cleans up any orphans that may be left on the list from the last use
+ * of this root.
+ */
+int btrfs_orphan_cleanup(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_key key, found_key;
+	struct btrfs_trans_handle *trans;
+	struct inode *inode;
+	u64 last_objectid = 0;
+	int ret = 0, nr_unlink = 0;
+
+	if (test_and_set_bit(BTRFS_ROOT_ORPHAN_CLEANUP, &root->state))
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	path->reada = READA_BACK;
+
+	key.objectid = BTRFS_ORPHAN_OBJECTID;
+	key.type = BTRFS_ORPHAN_ITEM_KEY;
+	key.offset = (u64)-1;
+
+	while (1) {
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		/*
+		 * if ret == 0 means we found what we were searching for, which
+		 * is weird, but possible, so only screw with path if we didn't
+		 * find the key and see if we have stuff that matches
+		 */
+		if (ret > 0) {
+			ret = 0;
+			if (path->slots[0] == 0)
+				break;
+			path->slots[0]--;
+		}
+
+		/* pull out the item */
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		/* make sure the item matches what we want */
+		if (found_key.objectid != BTRFS_ORPHAN_OBJECTID)
+			break;
+		if (found_key.type != BTRFS_ORPHAN_ITEM_KEY)
+			break;
+
+		/* release the path since we're done with it */
+		btrfs_release_path(path);
+
+		/*
+		 * this is where we are basically btrfs_lookup, without the
+		 * crossing root thing.  we store the inode number in the
+		 * offset of the orphan item.
+		 */
+
+		if (found_key.offset == last_objectid) {
+			/*
+			 * We found the same inode as before. This means we were
+			 * not able to remove its items via eviction triggered
+			 * by an iput(). A transaction abort may have happened,
+			 * due to -ENOSPC for example, so try to grab the error
+			 * that lead to a transaction abort, if any.
+			 */
+			btrfs_err(fs_info,
+				  "Error removing orphan entry, stopping orphan cleanup");
+			ret = BTRFS_FS_ERROR(fs_info) ?: -EINVAL;
+			goto out;
+		}
+
+		last_objectid = found_key.offset;
+
+		found_key.objectid = found_key.offset;
+		found_key.type = BTRFS_INODE_ITEM_KEY;
+		found_key.offset = 0;
+		inode = btrfs_iget(fs_info->sb, last_objectid, root);
+		if (IS_ERR(inode)) {
+			ret = PTR_ERR(inode);
+			inode = NULL;
+			if (ret != -ENOENT)
+				goto out;
+		}
+
+		if (!inode && root == fs_info->tree_root) {
+			struct btrfs_root *dead_root;
+			int is_dead_root = 0;
+
+			/*
+			 * This is an orphan in the tree root. Currently these
+			 * could come from 2 sources:
+			 *  a) a root (snapshot/subvolume) deletion in progress
+			 *  b) a free space cache inode
+			 * We need to distinguish those two, as the orphan item
+			 * for a root must not get deleted before the deletion
+			 * of the snapshot/subvolume's tree completes.
+			 *
+			 * btrfs_find_orphan_roots() ran before us, which has
+			 * found all deleted roots and loaded them into
+			 * fs_info->fs_roots_radix. So here we can find if an
+			 * orphan item corresponds to a deleted root by looking
+			 * up the root from that radix tree.
+			 */
+
+			spin_lock(&fs_info->fs_roots_radix_lock);
+			dead_root = radix_tree_lookup(&fs_info->fs_roots_radix,
+							 (unsigned long)found_key.objectid);
+			if (dead_root && btrfs_root_refs(&dead_root->root_item) == 0)
+				is_dead_root = 1;
+			spin_unlock(&fs_info->fs_roots_radix_lock);
+
+			if (is_dead_root) {
+				/* prevent this orphan from being found again */
+				key.offset = found_key.objectid - 1;
+				continue;
+			}
+
+		}
+
+		/*
+		 * If we have an inode with links, there are a couple of
+		 * possibilities:
+		 *
+		 * 1. We were halfway through creating fsverity metadata for the
+		 * file. In that case, the orphan item represents incomplete
+		 * fsverity metadata which must be cleaned up with
+		 * btrfs_drop_verity_items and deleting the orphan item.
+
+		 * 2. Old kernels (before v3.12) used to create an
+		 * orphan item for truncate indicating that there were possibly
+		 * extent items past i_size that needed to be deleted. In v3.12,
+		 * truncate was changed to update i_size in sync with the extent
+		 * items, but the (useless) orphan item was still created. Since
+		 * v4.18, we don't create the orphan item for truncate at all.
+		 *
+		 * So, this item could mean that we need to do a truncate, but
+		 * only if this filesystem was last used on a pre-v3.12 kernel
+		 * and was not cleanly unmounted. The odds of that are quite
+		 * slim, and it's a pain to do the truncate now, so just delete
+		 * the orphan item.
+		 *
+		 * It's also possible that this orphan item was supposed to be
+		 * deleted but wasn't. The inode number may have been reused,
+		 * but either way, we can delete the orphan item.
+		 */
+		if (!inode || inode->i_nlink) {
+			if (inode) {
+				ret = btrfs_drop_verity_items(BTRFS_I(inode));
+				iput(inode);
+				inode = NULL;
+				if (ret)
+					goto out;
+			}
+			trans = btrfs_start_transaction(root, 1);
+			if (IS_ERR(trans)) {
+				ret = PTR_ERR(trans);
+				goto out;
+			}
+			btrfs_debug(fs_info, "auto deleting %Lu",
+				    found_key.objectid);
+			ret = btrfs_del_orphan_item(trans, root,
+						    found_key.objectid);
+			btrfs_end_transaction(trans);
+			if (ret)
+				goto out;
+			continue;
+		}
+
+		nr_unlink++;
+
+		/* this will do delete_inode and everything for us */
+		iput(inode);
+	}
+	/* release the path since we're done with it */
+	btrfs_release_path(path);
+
+	if (test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state)) {
+		trans = btrfs_join_transaction(root);
+		if (!IS_ERR(trans))
+			btrfs_end_transaction(trans);
+	}
+
+	if (nr_unlink)
+		btrfs_debug(fs_info, "unlinked %d orphans", nr_unlink);
+
+out:
+	if (ret)
+		btrfs_err(fs_info, "could not do orphan cleanup %d", ret);
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * very simple check to peek ahead in the leaf looking for xattrs.  If we
+ * don't find any xattrs, we know there can't be any acls.
+ *
+ * slot is the slot the inode is in, objectid is the objectid of the inode
+ */
+static noinline int acls_after_inode_item(struct extent_buffer *leaf,
+					  int slot, u64 objectid,
+					  int *first_xattr_slot)
+{
+	u32 nritems = btrfs_header_nritems(leaf);
+	struct btrfs_key found_key;
+	static u64 xattr_access = 0;
+	static u64 xattr_default = 0;
+	int scanned = 0;
+
+	if (!xattr_access) {
+		xattr_access = btrfs_name_hash(XATTR_NAME_POSIX_ACL_ACCESS,
+					strlen(XATTR_NAME_POSIX_ACL_ACCESS));
+		xattr_default = btrfs_name_hash(XATTR_NAME_POSIX_ACL_DEFAULT,
+					strlen(XATTR_NAME_POSIX_ACL_DEFAULT));
+	}
+
+	slot++;
+	*first_xattr_slot = -1;
+	while (slot < nritems) {
+		btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+		/* we found a different objectid, there must not be acls */
+		if (found_key.objectid != objectid)
+			return 0;
+
+		/* we found an xattr, assume we've got an acl */
+		if (found_key.type == BTRFS_XATTR_ITEM_KEY) {
+			if (*first_xattr_slot == -1)
+				*first_xattr_slot = slot;
+			if (found_key.offset == xattr_access ||
+			    found_key.offset == xattr_default)
+				return 1;
+		}
+
+		/*
+		 * we found a key greater than an xattr key, there can't
+		 * be any acls later on
+		 */
+		if (found_key.type > BTRFS_XATTR_ITEM_KEY)
+			return 0;
+
+		slot++;
+		scanned++;
+
+		/*
+		 * it goes inode, inode backrefs, xattrs, extents,
+		 * so if there are a ton of hard links to an inode there can
+		 * be a lot of backrefs.  Don't waste time searching too hard,
+		 * this is just an optimization
+		 */
+		if (scanned >= 8)
+			break;
+	}
+	/* we hit the end of the leaf before we found an xattr or
+	 * something larger than an xattr.  We have to assume the inode
+	 * has acls
+	 */
+	if (*first_xattr_slot == -1)
+		*first_xattr_slot = slot;
+	return 1;
+}
+
+/*
+ * read an inode from the btree into the in-memory inode
+ */
+static int btrfs_read_locked_inode(struct inode *inode,
+				   struct btrfs_path *in_path)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_path *path = in_path;
+	struct extent_buffer *leaf;
+	struct btrfs_inode_item *inode_item;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_key location;
+	unsigned long ptr;
+	int maybe_acls;
+	u32 rdev;
+	int ret;
+	bool filled = false;
+	int first_xattr_slot;
+
+	ret = btrfs_fill_inode(inode, &rdev);
+	if (!ret)
+		filled = true;
+
+	if (!path) {
+		path = btrfs_alloc_path();
+		if (!path)
+			return -ENOMEM;
+	}
+
+	memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));
+
+	ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
+	if (ret) {
+		if (path != in_path)
+			btrfs_free_path(path);
+		return ret;
+	}
+
+	leaf = path->nodes[0];
+
+	if (filled)
+		goto cache_index;
+
+	inode_item = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_inode_item);
+	inode->i_mode = btrfs_inode_mode(leaf, inode_item);
+	set_nlink(inode, btrfs_inode_nlink(leaf, inode_item));
+	i_uid_write(inode, btrfs_inode_uid(leaf, inode_item));
+	i_gid_write(inode, btrfs_inode_gid(leaf, inode_item));
+	btrfs_i_size_write(BTRFS_I(inode), btrfs_inode_size(leaf, inode_item));
+	btrfs_inode_set_file_extent_range(BTRFS_I(inode), 0,
+			round_up(i_size_read(inode), fs_info->sectorsize));
+
+	inode->i_atime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->atime);
+	inode->i_atime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->atime);
+
+	inode->i_mtime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->mtime);
+	inode->i_mtime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->mtime);
+
+	inode_set_ctime(inode, btrfs_timespec_sec(leaf, &inode_item->ctime),
+			btrfs_timespec_nsec(leaf, &inode_item->ctime));
+
+	BTRFS_I(inode)->i_otime.tv_sec =
+		btrfs_timespec_sec(leaf, &inode_item->otime);
+	BTRFS_I(inode)->i_otime.tv_nsec =
+		btrfs_timespec_nsec(leaf, &inode_item->otime);
+
+	inode_set_bytes(inode, btrfs_inode_nbytes(leaf, inode_item));
+	BTRFS_I(inode)->generation = btrfs_inode_generation(leaf, inode_item);
+	BTRFS_I(inode)->last_trans = btrfs_inode_transid(leaf, inode_item);
+
+	inode_set_iversion_queried(inode,
+				   btrfs_inode_sequence(leaf, inode_item));
+	inode->i_generation = BTRFS_I(inode)->generation;
+	inode->i_rdev = 0;
+	rdev = btrfs_inode_rdev(leaf, inode_item);
+
+	BTRFS_I(inode)->index_cnt = (u64)-1;
+	btrfs_inode_split_flags(btrfs_inode_flags(leaf, inode_item),
+				&BTRFS_I(inode)->flags, &BTRFS_I(inode)->ro_flags);
+
+cache_index:
+	/*
+	 * If we were modified in the current generation and evicted from memory
+	 * and then re-read we need to do a full sync since we don't have any
+	 * idea about which extents were modified before we were evicted from
+	 * cache.
+	 *
+	 * This is required for both inode re-read from disk and delayed inode
+	 * in delayed_nodes_tree.
+	 */
+	if (BTRFS_I(inode)->last_trans == fs_info->generation)
+		set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
+			&BTRFS_I(inode)->runtime_flags);
+
+	/*
+	 * We don't persist the id of the transaction where an unlink operation
+	 * against the inode was last made. So here we assume the inode might
+	 * have been evicted, and therefore the exact value of last_unlink_trans
+	 * lost, and set it to last_trans to avoid metadata inconsistencies
+	 * between the inode and its parent if the inode is fsync'ed and the log
+	 * replayed. For example, in the scenario:
+	 *
+	 * touch mydir/foo
+	 * ln mydir/foo mydir/bar
+	 * sync
+	 * unlink mydir/bar
+	 * echo 2 > /proc/sys/vm/drop_caches   # evicts inode
+	 * xfs_io -c fsync mydir/foo
+	 * <power failure>
+	 * mount fs, triggers fsync log replay
+	 *
+	 * We must make sure that when we fsync our inode foo we also log its
+	 * parent inode, otherwise after log replay the parent still has the
+	 * dentry with the "bar" name but our inode foo has a link count of 1
+	 * and doesn't have an inode ref with the name "bar" anymore.
+	 *
+	 * Setting last_unlink_trans to last_trans is a pessimistic approach,
+	 * but it guarantees correctness at the expense of occasional full
+	 * transaction commits on fsync if our inode is a directory, or if our
+	 * inode is not a directory, logging its parent unnecessarily.
+	 */
+	BTRFS_I(inode)->last_unlink_trans = BTRFS_I(inode)->last_trans;
+
+	/*
+	 * Same logic as for last_unlink_trans. We don't persist the generation
+	 * of the last transaction where this inode was used for a reflink
+	 * operation, so after eviction and reloading the inode we must be
+	 * pessimistic and assume the last transaction that modified the inode.
+	 */
+	BTRFS_I(inode)->last_reflink_trans = BTRFS_I(inode)->last_trans;
+
+	path->slots[0]++;
+	if (inode->i_nlink != 1 ||
+	    path->slots[0] >= btrfs_header_nritems(leaf))
+		goto cache_acl;
+
+	btrfs_item_key_to_cpu(leaf, &location, path->slots[0]);
+	if (location.objectid != btrfs_ino(BTRFS_I(inode)))
+		goto cache_acl;
+
+	ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+	if (location.type == BTRFS_INODE_REF_KEY) {
+		struct btrfs_inode_ref *ref;
+
+		ref = (struct btrfs_inode_ref *)ptr;
+		BTRFS_I(inode)->dir_index = btrfs_inode_ref_index(leaf, ref);
+	} else if (location.type == BTRFS_INODE_EXTREF_KEY) {
+		struct btrfs_inode_extref *extref;
+
+		extref = (struct btrfs_inode_extref *)ptr;
+		BTRFS_I(inode)->dir_index = btrfs_inode_extref_index(leaf,
+								     extref);
+	}
+cache_acl:
+	/*
+	 * try to precache a NULL acl entry for files that don't have
+	 * any xattrs or acls
+	 */
+	maybe_acls = acls_after_inode_item(leaf, path->slots[0],
+			btrfs_ino(BTRFS_I(inode)), &first_xattr_slot);
+	if (first_xattr_slot != -1) {
+		path->slots[0] = first_xattr_slot;
+		ret = btrfs_load_inode_props(inode, path);
+		if (ret)
+			btrfs_err(fs_info,
+				  "error loading props for ino %llu (root %llu): %d",
+				  btrfs_ino(BTRFS_I(inode)),
+				  root->root_key.objectid, ret);
+	}
+	if (path != in_path)
+		btrfs_free_path(path);
+
+	if (!maybe_acls)
+		cache_no_acl(inode);
+
+	switch (inode->i_mode & S_IFMT) {
+	case S_IFREG:
+		inode->i_mapping->a_ops = &btrfs_aops;
+		inode->i_fop = &btrfs_file_operations;
+		inode->i_op = &btrfs_file_inode_operations;
+		break;
+	case S_IFDIR:
+		inode->i_fop = &btrfs_dir_file_operations;
+		inode->i_op = &btrfs_dir_inode_operations;
+		break;
+	case S_IFLNK:
+		inode->i_op = &btrfs_symlink_inode_operations;
+		inode_nohighmem(inode);
+		inode->i_mapping->a_ops = &btrfs_aops;
+		break;
+	default:
+		inode->i_op = &btrfs_special_inode_operations;
+		init_special_inode(inode, inode->i_mode, rdev);
+		break;
+	}
+
+	btrfs_sync_inode_flags_to_i_flags(inode);
+	return 0;
+}
+
+/*
+ * given a leaf and an inode, copy the inode fields into the leaf
+ */
+static void fill_inode_item(struct btrfs_trans_handle *trans,
+			    struct extent_buffer *leaf,
+			    struct btrfs_inode_item *item,
+			    struct inode *inode)
+{
+	struct btrfs_map_token token;
+	u64 flags;
+
+	btrfs_init_map_token(&token, leaf);
+
+	btrfs_set_token_inode_uid(&token, item, i_uid_read(inode));
+	btrfs_set_token_inode_gid(&token, item, i_gid_read(inode));
+	btrfs_set_token_inode_size(&token, item, BTRFS_I(inode)->disk_i_size);
+	btrfs_set_token_inode_mode(&token, item, inode->i_mode);
+	btrfs_set_token_inode_nlink(&token, item, inode->i_nlink);
+
+	btrfs_set_token_timespec_sec(&token, &item->atime,
+				     inode->i_atime.tv_sec);
+	btrfs_set_token_timespec_nsec(&token, &item->atime,
+				      inode->i_atime.tv_nsec);
+
+	btrfs_set_token_timespec_sec(&token, &item->mtime,
+				     inode->i_mtime.tv_sec);
+	btrfs_set_token_timespec_nsec(&token, &item->mtime,
+				      inode->i_mtime.tv_nsec);
+
+	btrfs_set_token_timespec_sec(&token, &item->ctime,
+				     inode_get_ctime(inode).tv_sec);
+	btrfs_set_token_timespec_nsec(&token, &item->ctime,
+				      inode_get_ctime(inode).tv_nsec);
+
+	btrfs_set_token_timespec_sec(&token, &item->otime,
+				     BTRFS_I(inode)->i_otime.tv_sec);
+	btrfs_set_token_timespec_nsec(&token, &item->otime,
+				      BTRFS_I(inode)->i_otime.tv_nsec);
+
+	btrfs_set_token_inode_nbytes(&token, item, inode_get_bytes(inode));
+	btrfs_set_token_inode_generation(&token, item,
+					 BTRFS_I(inode)->generation);
+	btrfs_set_token_inode_sequence(&token, item, inode_peek_iversion(inode));
+	btrfs_set_token_inode_transid(&token, item, trans->transid);
+	btrfs_set_token_inode_rdev(&token, item, inode->i_rdev);
+	flags = btrfs_inode_combine_flags(BTRFS_I(inode)->flags,
+					  BTRFS_I(inode)->ro_flags);
+	btrfs_set_token_inode_flags(&token, item, flags);
+	btrfs_set_token_inode_block_group(&token, item, 0);
+}
+
+/*
+ * copy everything in the in-memory inode into the btree.
+ */
+static noinline int btrfs_update_inode_item(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				struct btrfs_inode *inode)
+{
+	struct btrfs_inode_item *inode_item;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_lookup_inode(trans, root, path, &inode->location, 1);
+	if (ret) {
+		if (ret > 0)
+			ret = -ENOENT;
+		goto failed;
+	}
+
+	leaf = path->nodes[0];
+	inode_item = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_inode_item);
+
+	fill_inode_item(trans, leaf, inode_item, &inode->vfs_inode);
+	btrfs_mark_buffer_dirty(trans, leaf);
+	btrfs_set_inode_last_trans(trans, inode);
+	ret = 0;
+failed:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * copy everything in the in-memory inode into the btree.
+ */
+noinline int btrfs_update_inode(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+
+	/*
+	 * If the inode is a free space inode, we can deadlock during commit
+	 * if we put it into the delayed code.
+	 *
+	 * The data relocation inode should also be directly updated
+	 * without delay
+	 */
+	if (!btrfs_is_free_space_inode(inode)
+	    && !btrfs_is_data_reloc_root(root)
+	    && !test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags)) {
+		btrfs_update_root_times(trans, root);
+
+		ret = btrfs_delayed_update_inode(trans, root, inode);
+		if (!ret)
+			btrfs_set_inode_last_trans(trans, inode);
+		return ret;
+	}
+
+	return btrfs_update_inode_item(trans, root, inode);
+}
+
+int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root, struct btrfs_inode *inode)
+{
+	int ret;
+
+	ret = btrfs_update_inode(trans, root, inode);
+	if (ret == -ENOSPC)
+		return btrfs_update_inode_item(trans, root, inode);
+	return ret;
+}
+
+/*
+ * unlink helper that gets used here in inode.c and in the tree logging
+ * recovery code.  It remove a link in a directory with a given name, and
+ * also drops the back refs in the inode to the directory
+ */
+static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+				struct btrfs_inode *dir,
+				struct btrfs_inode *inode,
+				const struct fscrypt_str *name,
+				struct btrfs_rename_ctx *rename_ctx)
+{
+	struct btrfs_root *root = dir->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_path *path;
+	int ret = 0;
+	struct btrfs_dir_item *di;
+	u64 index;
+	u64 ino = btrfs_ino(inode);
+	u64 dir_ino = btrfs_ino(dir);
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	di = btrfs_lookup_dir_item(trans, root, path, dir_ino, name, -1);
+	if (IS_ERR_OR_NULL(di)) {
+		ret = di ? PTR_ERR(di) : -ENOENT;
+		goto err;
+	}
+	ret = btrfs_delete_one_dir_name(trans, root, path, di);
+	if (ret)
+		goto err;
+	btrfs_release_path(path);
+
+	/*
+	 * If we don't have dir index, we have to get it by looking up
+	 * the inode ref, since we get the inode ref, remove it directly,
+	 * it is unnecessary to do delayed deletion.
+	 *
+	 * But if we have dir index, needn't search inode ref to get it.
+	 * Since the inode ref is close to the inode item, it is better
+	 * that we delay to delete it, and just do this deletion when
+	 * we update the inode item.
+	 */
+	if (inode->dir_index) {
+		ret = btrfs_delayed_delete_inode_ref(inode);
+		if (!ret) {
+			index = inode->dir_index;
+			goto skip_backref;
+		}
+	}
+
+	ret = btrfs_del_inode_ref(trans, root, name, ino, dir_ino, &index);
+	if (ret) {
+		btrfs_info(fs_info,
+			"failed to delete reference to %.*s, inode %llu parent %llu",
+			name->len, name->name, ino, dir_ino);
+		btrfs_abort_transaction(trans, ret);
+		goto err;
+	}
+skip_backref:
+	if (rename_ctx)
+		rename_ctx->index = index;
+
+	ret = btrfs_delete_delayed_dir_index(trans, dir, index);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto err;
+	}
+
+	/*
+	 * If we are in a rename context, we don't need to update anything in the
+	 * log. That will be done later during the rename by btrfs_log_new_name().
+	 * Besides that, doing it here would only cause extra unnecessary btree
+	 * operations on the log tree, increasing latency for applications.
+	 */
+	if (!rename_ctx) {
+		btrfs_del_inode_ref_in_log(trans, root, name, inode, dir_ino);
+		btrfs_del_dir_entries_in_log(trans, root, name, dir, index);
+	}
+
+	/*
+	 * If we have a pending delayed iput we could end up with the final iput
+	 * being run in btrfs-cleaner context.  If we have enough of these built
+	 * up we can end up burning a lot of time in btrfs-cleaner without any
+	 * way to throttle the unlinks.  Since we're currently holding a ref on
+	 * the inode we can run the delayed iput here without any issues as the
+	 * final iput won't be done until after we drop the ref we're currently
+	 * holding.
+	 */
+	btrfs_run_delayed_iput(fs_info, inode);
+err:
+	btrfs_free_path(path);
+	if (ret)
+		goto out;
+
+	btrfs_i_size_write(dir, dir->vfs_inode.i_size - name->len * 2);
+	inode_inc_iversion(&inode->vfs_inode);
+	inode_inc_iversion(&dir->vfs_inode);
+	inode_set_ctime_current(&inode->vfs_inode);
+	dir->vfs_inode.i_mtime = inode_set_ctime_current(&dir->vfs_inode);
+	ret = btrfs_update_inode(trans, root, dir);
+out:
+	return ret;
+}
+
+int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+		       struct btrfs_inode *dir, struct btrfs_inode *inode,
+		       const struct fscrypt_str *name)
+{
+	int ret;
+
+	ret = __btrfs_unlink_inode(trans, dir, inode, name, NULL);
+	if (!ret) {
+		drop_nlink(&inode->vfs_inode);
+		ret = btrfs_update_inode(trans, inode->root, inode);
+	}
+	return ret;
+}
+
+/*
+ * helper to start transaction for unlink and rmdir.
+ *
+ * unlink and rmdir are special in btrfs, they do not always free space, so
+ * if we cannot make our reservations the normal way try and see if there is
+ * plenty of slack room in the global reserve to migrate, otherwise we cannot
+ * allow the unlink to occur.
+ */
+static struct btrfs_trans_handle *__unlink_start_trans(struct btrfs_inode *dir)
+{
+	struct btrfs_root *root = dir->root;
+
+	return btrfs_start_transaction_fallback_global_rsv(root,
+						   BTRFS_UNLINK_METADATA_UNITS);
+}
+
+static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct btrfs_trans_handle *trans;
+	struct inode *inode = d_inode(dentry);
+	int ret;
+	struct fscrypt_name fname;
+
+	ret = fscrypt_setup_filename(dir, &dentry->d_name, 1, &fname);
+	if (ret)
+		return ret;
+
+	/* This needs to handle no-key deletions later on */
+
+	trans = __unlink_start_trans(BTRFS_I(dir));
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto fscrypt_free;
+	}
+
+	btrfs_record_unlink_dir(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
+				false);
+
+	ret = btrfs_unlink_inode(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
+				 &fname.disk_name);
+	if (ret)
+		goto end_trans;
+
+	if (inode->i_nlink == 0) {
+		ret = btrfs_orphan_add(trans, BTRFS_I(inode));
+		if (ret)
+			goto end_trans;
+	}
+
+end_trans:
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(BTRFS_I(dir)->root->fs_info);
+fscrypt_free:
+	fscrypt_free_filename(&fname);
+	return ret;
+}
+
+static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
+			       struct btrfs_inode *dir, struct dentry *dentry)
+{
+	struct btrfs_root *root = dir->root;
+	struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_dir_item *di;
+	struct btrfs_key key;
+	u64 index;
+	int ret;
+	u64 objectid;
+	u64 dir_ino = btrfs_ino(dir);
+	struct fscrypt_name fname;
+
+	ret = fscrypt_setup_filename(&dir->vfs_inode, &dentry->d_name, 1, &fname);
+	if (ret)
+		return ret;
+
+	/* This needs to handle no-key deletions later on */
+
+	if (btrfs_ino(inode) == BTRFS_FIRST_FREE_OBJECTID) {
+		objectid = inode->root->root_key.objectid;
+	} else if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
+		objectid = inode->location.objectid;
+	} else {
+		WARN_ON(1);
+		fscrypt_free_filename(&fname);
+		return -EINVAL;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
+				   &fname.disk_name, -1);
+	if (IS_ERR_OR_NULL(di)) {
+		ret = di ? PTR_ERR(di) : -ENOENT;
+		goto out;
+	}
+
+	leaf = path->nodes[0];
+	btrfs_dir_item_key_to_cpu(leaf, di, &key);
+	WARN_ON(key.type != BTRFS_ROOT_ITEM_KEY || key.objectid != objectid);
+	ret = btrfs_delete_one_dir_name(trans, root, path, di);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+	btrfs_release_path(path);
+
+	/*
+	 * This is a placeholder inode for a subvolume we didn't have a
+	 * reference to at the time of the snapshot creation.  In the meantime
+	 * we could have renamed the real subvol link into our snapshot, so
+	 * depending on btrfs_del_root_ref to return -ENOENT here is incorrect.
+	 * Instead simply lookup the dir_index_item for this entry so we can
+	 * remove it.  Otherwise we know we have a ref to the root and we can
+	 * call btrfs_del_root_ref, and it _shouldn't_ fail.
+	 */
+	if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
+		di = btrfs_search_dir_index_item(root, path, dir_ino, &fname.disk_name);
+		if (IS_ERR_OR_NULL(di)) {
+			if (!di)
+				ret = -ENOENT;
+			else
+				ret = PTR_ERR(di);
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		index = key.offset;
+		btrfs_release_path(path);
+	} else {
+		ret = btrfs_del_root_ref(trans, objectid,
+					 root->root_key.objectid, dir_ino,
+					 &index, &fname.disk_name);
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+	}
+
+	ret = btrfs_delete_delayed_dir_index(trans, dir, index);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	btrfs_i_size_write(dir, dir->vfs_inode.i_size - fname.disk_name.len * 2);
+	inode_inc_iversion(&dir->vfs_inode);
+	dir->vfs_inode.i_mtime = inode_set_ctime_current(&dir->vfs_inode);
+	ret = btrfs_update_inode_fallback(trans, root, dir);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+out:
+	btrfs_free_path(path);
+	fscrypt_free_filename(&fname);
+	return ret;
+}
+
+/*
+ * Helper to check if the subvolume references other subvolumes or if it's
+ * default.
+ */
+static noinline int may_destroy_subvol(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_path *path;
+	struct btrfs_dir_item *di;
+	struct btrfs_key key;
+	struct fscrypt_str name = FSTR_INIT("default", 7);
+	u64 dir_id;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	/* Make sure this root isn't set as the default subvol */
+	dir_id = btrfs_super_root_dir(fs_info->super_copy);
+	di = btrfs_lookup_dir_item(NULL, fs_info->tree_root, path,
+				   dir_id, &name, 0);
+	if (di && !IS_ERR(di)) {
+		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
+		if (key.objectid == root->root_key.objectid) {
+			ret = -EPERM;
+			btrfs_err(fs_info,
+				  "deleting default subvolume %llu is not allowed",
+				  key.objectid);
+			goto out;
+		}
+		btrfs_release_path(path);
+	}
+
+	key.objectid = root->root_key.objectid;
+	key.type = BTRFS_ROOT_REF_KEY;
+	key.offset = (u64)-1;
+
+	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+	BUG_ON(ret == 0);
+
+	ret = 0;
+	if (path->slots[0] > 0) {
+		path->slots[0]--;
+		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+		if (key.objectid == root->root_key.objectid &&
+		    key.type == BTRFS_ROOT_REF_KEY)
+			ret = -ENOTEMPTY;
+	}
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/* Delete all dentries for inodes belonging to the root */
+static void btrfs_prune_dentries(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct rb_node *node;
+	struct rb_node *prev;
+	struct btrfs_inode *entry;
+	struct inode *inode;
+	u64 objectid = 0;
+
+	if (!BTRFS_FS_ERROR(fs_info))
+		WARN_ON(btrfs_root_refs(&root->root_item) != 0);
+
+	spin_lock(&root->inode_lock);
+again:
+	node = root->inode_tree.rb_node;
+	prev = NULL;
+	while (node) {
+		prev = node;
+		entry = rb_entry(node, struct btrfs_inode, rb_node);
+
+		if (objectid < btrfs_ino(entry))
+			node = node->rb_left;
+		else if (objectid > btrfs_ino(entry))
+			node = node->rb_right;
+		else
+			break;
+	}
+	if (!node) {
+		while (prev) {
+			entry = rb_entry(prev, struct btrfs_inode, rb_node);
+			if (objectid <= btrfs_ino(entry)) {
+				node = prev;
+				break;
+			}
+			prev = rb_next(prev);
+		}
+	}
+	while (node) {
+		entry = rb_entry(node, struct btrfs_inode, rb_node);
+		objectid = btrfs_ino(entry) + 1;
+		inode = igrab(&entry->vfs_inode);
+		if (inode) {
+			spin_unlock(&root->inode_lock);
+			if (atomic_read(&inode->i_count) > 1)
+				d_prune_aliases(inode);
+			/*
+			 * btrfs_drop_inode will have it removed from the inode
+			 * cache when its usage count hits zero.
+			 */
+			iput(inode);
+			cond_resched();
+			spin_lock(&root->inode_lock);
+			goto again;
+		}
+
+		if (cond_resched_lock(&root->inode_lock))
+			goto again;
+
+		node = rb_next(node);
+	}
+	spin_unlock(&root->inode_lock);
+}
+
+int btrfs_delete_subvolume(struct btrfs_inode *dir, struct dentry *dentry)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
+	struct btrfs_root *root = dir->root;
+	struct inode *inode = d_inode(dentry);
+	struct btrfs_root *dest = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_block_rsv block_rsv;
+	u64 root_flags;
+	int ret;
+
+	down_write(&fs_info->subvol_sem);
+
+	/*
+	 * Don't allow to delete a subvolume with send in progress. This is
+	 * inside the inode lock so the error handling that has to drop the bit
+	 * again is not run concurrently.
+	 */
+	spin_lock(&dest->root_item_lock);
+	if (dest->send_in_progress) {
+		spin_unlock(&dest->root_item_lock);
+		btrfs_warn(fs_info,
+			   "attempt to delete subvolume %llu during send",
+			   dest->root_key.objectid);
+		ret = -EPERM;
+		goto out_up_write;
+	}
+	if (atomic_read(&dest->nr_swapfiles)) {
+		spin_unlock(&dest->root_item_lock);
+		btrfs_warn(fs_info,
+			   "attempt to delete subvolume %llu with active swapfile",
+			   root->root_key.objectid);
+		ret = -EPERM;
+		goto out_up_write;
+	}
+	root_flags = btrfs_root_flags(&dest->root_item);
+	btrfs_set_root_flags(&dest->root_item,
+			     root_flags | BTRFS_ROOT_SUBVOL_DEAD);
+	spin_unlock(&dest->root_item_lock);
+
+	ret = may_destroy_subvol(dest);
+	if (ret)
+		goto out_undead;
+
+	btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
+	/*
+	 * One for dir inode,
+	 * two for dir entries,
+	 * two for root ref/backref.
+	 */
+	ret = btrfs_subvolume_reserve_metadata(root, &block_rsv, 5, true);
+	if (ret)
+		goto out_undead;
+
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_release;
+	}
+	trans->block_rsv = &block_rsv;
+	trans->bytes_reserved = block_rsv.size;
+
+	btrfs_record_snapshot_destroy(trans, dir);
+
+	ret = btrfs_unlink_subvol(trans, dir, dentry);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_end_trans;
+	}
+
+	ret = btrfs_record_root_in_trans(trans, dest);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_end_trans;
+	}
+
+	memset(&dest->root_item.drop_progress, 0,
+		sizeof(dest->root_item.drop_progress));
+	btrfs_set_root_drop_level(&dest->root_item, 0);
+	btrfs_set_root_refs(&dest->root_item, 0);
+
+	if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
+		ret = btrfs_insert_orphan_item(trans,
+					fs_info->tree_root,
+					dest->root_key.objectid);
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_end_trans;
+		}
+	}
+
+	ret = btrfs_uuid_tree_remove(trans, dest->root_item.uuid,
+				  BTRFS_UUID_KEY_SUBVOL,
+				  dest->root_key.objectid);
+	if (ret && ret != -ENOENT) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_end_trans;
+	}
+	if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
+		ret = btrfs_uuid_tree_remove(trans,
+					  dest->root_item.received_uuid,
+					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+					  dest->root_key.objectid);
+		if (ret && ret != -ENOENT) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_end_trans;
+		}
+	}
+
+	free_anon_bdev(dest->anon_dev);
+	dest->anon_dev = 0;
+out_end_trans:
+	trans->block_rsv = NULL;
+	trans->bytes_reserved = 0;
+	ret = btrfs_end_transaction(trans);
+	inode->i_flags |= S_DEAD;
+out_release:
+	btrfs_subvolume_release_metadata(root, &block_rsv);
+out_undead:
+	if (ret) {
+		spin_lock(&dest->root_item_lock);
+		root_flags = btrfs_root_flags(&dest->root_item);
+		btrfs_set_root_flags(&dest->root_item,
+				root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
+		spin_unlock(&dest->root_item_lock);
+	}
+out_up_write:
+	up_write(&fs_info->subvol_sem);
+	if (!ret) {
+		d_invalidate(dentry);
+		btrfs_prune_dentries(dest);
+		ASSERT(dest->send_in_progress == 0);
+	}
+
+	return ret;
+}
+
+static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+	int err = 0;
+	struct btrfs_trans_handle *trans;
+	u64 last_unlink_trans;
+	struct fscrypt_name fname;
+
+	if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
+		return -ENOTEMPTY;
+	if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID) {
+		if (unlikely(btrfs_fs_incompat(fs_info, EXTENT_TREE_V2))) {
+			btrfs_err(fs_info,
+			"extent tree v2 doesn't support snapshot deletion yet");
+			return -EOPNOTSUPP;
+		}
+		return btrfs_delete_subvolume(BTRFS_I(dir), dentry);
+	}
+
+	err = fscrypt_setup_filename(dir, &dentry->d_name, 1, &fname);
+	if (err)
+		return err;
+
+	/* This needs to handle no-key deletions later on */
+
+	trans = __unlink_start_trans(BTRFS_I(dir));
+	if (IS_ERR(trans)) {
+		err = PTR_ERR(trans);
+		goto out_notrans;
+	}
+
+	if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
+		err = btrfs_unlink_subvol(trans, BTRFS_I(dir), dentry);
+		goto out;
+	}
+
+	err = btrfs_orphan_add(trans, BTRFS_I(inode));
+	if (err)
+		goto out;
+
+	last_unlink_trans = BTRFS_I(inode)->last_unlink_trans;
+
+	/* now the directory is empty */
+	err = btrfs_unlink_inode(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
+				 &fname.disk_name);
+	if (!err) {
+		btrfs_i_size_write(BTRFS_I(inode), 0);
+		/*
+		 * Propagate the last_unlink_trans value of the deleted dir to
+		 * its parent directory. This is to prevent an unrecoverable
+		 * log tree in the case we do something like this:
+		 * 1) create dir foo
+		 * 2) create snapshot under dir foo
+		 * 3) delete the snapshot
+		 * 4) rmdir foo
+		 * 5) mkdir foo
+		 * 6) fsync foo or some file inside foo
+		 */
+		if (last_unlink_trans >= trans->transid)
+			BTRFS_I(dir)->last_unlink_trans = last_unlink_trans;
+	}
+out:
+	btrfs_end_transaction(trans);
+out_notrans:
+	btrfs_btree_balance_dirty(fs_info);
+	fscrypt_free_filename(&fname);
+
+	return err;
+}
+
+/*
+ * btrfs_truncate_block - read, zero a chunk and write a block
+ * @inode - inode that we're zeroing
+ * @from - the offset to start zeroing
+ * @len - the length to zero, 0 to zero the entire range respective to the
+ *	offset
+ * @front - zero up to the offset instead of from the offset on
+ *
+ * This will find the block for the "from" offset and cow the block and zero the
+ * part we want to zero.  This is used with truncate and hole punching.
+ */
+int btrfs_truncate_block(struct btrfs_inode *inode, loff_t from, loff_t len,
+			 int front)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct address_space *mapping = inode->vfs_inode.i_mapping;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct btrfs_ordered_extent *ordered;
+	struct extent_state *cached_state = NULL;
+	struct extent_changeset *data_reserved = NULL;
+	bool only_release_metadata = false;
+	u32 blocksize = fs_info->sectorsize;
+	pgoff_t index = from >> PAGE_SHIFT;
+	unsigned offset = from & (blocksize - 1);
+	struct page *page;
+	gfp_t mask = btrfs_alloc_write_mask(mapping);
+	size_t write_bytes = blocksize;
+	int ret = 0;
+	u64 block_start;
+	u64 block_end;
+
+	if (IS_ALIGNED(offset, blocksize) &&
+	    (!len || IS_ALIGNED(len, blocksize)))
+		goto out;
+
+	block_start = round_down(from, blocksize);
+	block_end = block_start + blocksize - 1;
+
+	ret = btrfs_check_data_free_space(inode, &data_reserved, block_start,
+					  blocksize, false);
+	if (ret < 0) {
+		if (btrfs_check_nocow_lock(inode, block_start, &write_bytes, false) > 0) {
+			/* For nocow case, no need to reserve data space */
+			only_release_metadata = true;
+		} else {
+			goto out;
+		}
+	}
+	ret = btrfs_delalloc_reserve_metadata(inode, blocksize, blocksize, false);
+	if (ret < 0) {
+		if (!only_release_metadata)
+			btrfs_free_reserved_data_space(inode, data_reserved,
+						       block_start, blocksize);
+		goto out;
+	}
+again:
+	page = find_or_create_page(mapping, index, mask);
+	if (!page) {
+		btrfs_delalloc_release_space(inode, data_reserved, block_start,
+					     blocksize, true);
+		btrfs_delalloc_release_extents(inode, blocksize);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (!PageUptodate(page)) {
+		ret = btrfs_read_folio(NULL, page_folio(page));
+		lock_page(page);
+		if (page->mapping != mapping) {
+			unlock_page(page);
+			put_page(page);
+			goto again;
+		}
+		if (!PageUptodate(page)) {
+			ret = -EIO;
+			goto out_unlock;
+		}
+	}
+
+	/*
+	 * We unlock the page after the io is completed and then re-lock it
+	 * above.  release_folio() could have come in between that and cleared
+	 * PagePrivate(), but left the page in the mapping.  Set the page mapped
+	 * here to make sure it's properly set for the subpage stuff.
+	 */
+	ret = set_page_extent_mapped(page);
+	if (ret < 0)
+		goto out_unlock;
+
+	wait_on_page_writeback(page);
+
+	lock_extent(io_tree, block_start, block_end, &cached_state);
+
+	ordered = btrfs_lookup_ordered_extent(inode, block_start);
+	if (ordered) {
+		unlock_extent(io_tree, block_start, block_end, &cached_state);
+		unlock_page(page);
+		put_page(page);
+		btrfs_start_ordered_extent(ordered);
+		btrfs_put_ordered_extent(ordered);
+		goto again;
+	}
+
+	clear_extent_bit(&inode->io_tree, block_start, block_end,
+			 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
+			 &cached_state);
+
+	ret = btrfs_set_extent_delalloc(inode, block_start, block_end, 0,
+					&cached_state);
+	if (ret) {
+		unlock_extent(io_tree, block_start, block_end, &cached_state);
+		goto out_unlock;
+	}
+
+	if (offset != blocksize) {
+		if (!len)
+			len = blocksize - offset;
+		if (front)
+			memzero_page(page, (block_start - page_offset(page)),
+				     offset);
+		else
+			memzero_page(page, (block_start - page_offset(page)) + offset,
+				     len);
+	}
+	btrfs_page_clear_checked(fs_info, page, block_start,
+				 block_end + 1 - block_start);
+	btrfs_page_set_dirty(fs_info, page, block_start, block_end + 1 - block_start);
+	unlock_extent(io_tree, block_start, block_end, &cached_state);
+
+	if (only_release_metadata)
+		set_extent_bit(&inode->io_tree, block_start, block_end,
+			       EXTENT_NORESERVE, NULL);
+
+out_unlock:
+	if (ret) {
+		if (only_release_metadata)
+			btrfs_delalloc_release_metadata(inode, blocksize, true);
+		else
+			btrfs_delalloc_release_space(inode, data_reserved,
+					block_start, blocksize, true);
+	}
+	btrfs_delalloc_release_extents(inode, blocksize);
+	unlock_page(page);
+	put_page(page);
+out:
+	if (only_release_metadata)
+		btrfs_check_nocow_unlock(inode);
+	extent_changeset_free(data_reserved);
+	return ret;
+}
+
+static int maybe_insert_hole(struct btrfs_root *root, struct btrfs_inode *inode,
+			     u64 offset, u64 len)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_drop_extents_args drop_args = { 0 };
+	int ret;
+
+	/*
+	 * If NO_HOLES is enabled, we don't need to do anything.
+	 * Later, up in the call chain, either btrfs_set_inode_last_sub_trans()
+	 * or btrfs_update_inode() will be called, which guarantee that the next
+	 * fsync will know this inode was changed and needs to be logged.
+	 */
+	if (btrfs_fs_incompat(fs_info, NO_HOLES))
+		return 0;
+
+	/*
+	 * 1 - for the one we're dropping
+	 * 1 - for the one we're adding
+	 * 1 - for updating the inode.
+	 */
+	trans = btrfs_start_transaction(root, 3);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	drop_args.start = offset;
+	drop_args.end = offset + len;
+	drop_args.drop_cache = true;
+
+	ret = btrfs_drop_extents(trans, root, inode, &drop_args);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		btrfs_end_transaction(trans);
+		return ret;
+	}
+
+	ret = btrfs_insert_hole_extent(trans, root, btrfs_ino(inode), offset, len);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+	} else {
+		btrfs_update_inode_bytes(inode, 0, drop_args.bytes_found);
+		btrfs_update_inode(trans, root, inode);
+	}
+	btrfs_end_transaction(trans);
+	return ret;
+}
+
+/*
+ * This function puts in dummy file extents for the area we're creating a hole
+ * for.  So if we are truncating this file to a larger size we need to insert
+ * these file extents so that btrfs_get_extent will return a EXTENT_MAP_HOLE for
+ * the range between oldsize and size
+ */
+int btrfs_cont_expand(struct btrfs_inode *inode, loff_t oldsize, loff_t size)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct extent_map *em = NULL;
+	struct extent_state *cached_state = NULL;
+	u64 hole_start = ALIGN(oldsize, fs_info->sectorsize);
+	u64 block_end = ALIGN(size, fs_info->sectorsize);
+	u64 last_byte;
+	u64 cur_offset;
+	u64 hole_size;
+	int err = 0;
+
+	/*
+	 * If our size started in the middle of a block we need to zero out the
+	 * rest of the block before we expand the i_size, otherwise we could
+	 * expose stale data.
+	 */
+	err = btrfs_truncate_block(inode, oldsize, 0, 0);
+	if (err)
+		return err;
+
+	if (size <= hole_start)
+		return 0;
+
+	btrfs_lock_and_flush_ordered_range(inode, hole_start, block_end - 1,
+					   &cached_state);
+	cur_offset = hole_start;
+	while (1) {
+		em = btrfs_get_extent(inode, NULL, 0, cur_offset,
+				      block_end - cur_offset);
+		if (IS_ERR(em)) {
+			err = PTR_ERR(em);
+			em = NULL;
+			break;
+		}
+		last_byte = min(extent_map_end(em), block_end);
+		last_byte = ALIGN(last_byte, fs_info->sectorsize);
+		hole_size = last_byte - cur_offset;
+
+		if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
+			struct extent_map *hole_em;
+
+			err = maybe_insert_hole(root, inode, cur_offset,
+						hole_size);
+			if (err)
+				break;
+
+			err = btrfs_inode_set_file_extent_range(inode,
+							cur_offset, hole_size);
+			if (err)
+				break;
+
+			hole_em = alloc_extent_map();
+			if (!hole_em) {
+				btrfs_drop_extent_map_range(inode, cur_offset,
+						    cur_offset + hole_size - 1,
+						    false);
+				btrfs_set_inode_full_sync(inode);
+				goto next;
+			}
+			hole_em->start = cur_offset;
+			hole_em->len = hole_size;
+			hole_em->orig_start = cur_offset;
+
+			hole_em->block_start = EXTENT_MAP_HOLE;
+			hole_em->block_len = 0;
+			hole_em->orig_block_len = 0;
+			hole_em->ram_bytes = hole_size;
+			hole_em->compress_type = BTRFS_COMPRESS_NONE;
+			hole_em->generation = fs_info->generation;
+
+			err = btrfs_replace_extent_map_range(inode, hole_em, true);
+			free_extent_map(hole_em);
+		} else {
+			err = btrfs_inode_set_file_extent_range(inode,
+							cur_offset, hole_size);
+			if (err)
+				break;
+		}
+next:
+		free_extent_map(em);
+		em = NULL;
+		cur_offset = last_byte;
+		if (cur_offset >= block_end)
+			break;
+	}
+	free_extent_map(em);
+	unlock_extent(io_tree, hole_start, block_end - 1, &cached_state);
+	return err;
+}
+
+static int btrfs_setsize(struct inode *inode, struct iattr *attr)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+	loff_t oldsize = i_size_read(inode);
+	loff_t newsize = attr->ia_size;
+	int mask = attr->ia_valid;
+	int ret;
+
+	/*
+	 * The regular truncate() case without ATTR_CTIME and ATTR_MTIME is a
+	 * special case where we need to update the times despite not having
+	 * these flags set.  For all other operations the VFS set these flags
+	 * explicitly if it wants a timestamp update.
+	 */
+	if (newsize != oldsize) {
+		inode_inc_iversion(inode);
+		if (!(mask & (ATTR_CTIME | ATTR_MTIME))) {
+			inode->i_mtime = inode_set_ctime_current(inode);
+		}
+	}
+
+	if (newsize > oldsize) {
+		/*
+		 * Don't do an expanding truncate while snapshotting is ongoing.
+		 * This is to ensure the snapshot captures a fully consistent
+		 * state of this file - if the snapshot captures this expanding
+		 * truncation, it must capture all writes that happened before
+		 * this truncation.
+		 */
+		btrfs_drew_write_lock(&root->snapshot_lock);
+		ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, newsize);
+		if (ret) {
+			btrfs_drew_write_unlock(&root->snapshot_lock);
+			return ret;
+		}
+
+		trans = btrfs_start_transaction(root, 1);
+		if (IS_ERR(trans)) {
+			btrfs_drew_write_unlock(&root->snapshot_lock);
+			return PTR_ERR(trans);
+		}
+
+		i_size_write(inode, newsize);
+		btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
+		pagecache_isize_extended(inode, oldsize, newsize);
+		ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
+		btrfs_drew_write_unlock(&root->snapshot_lock);
+		btrfs_end_transaction(trans);
+	} else {
+		struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+		if (btrfs_is_zoned(fs_info)) {
+			ret = btrfs_wait_ordered_range(inode,
+					ALIGN(newsize, fs_info->sectorsize),
+					(u64)-1);
+			if (ret)
+				return ret;
+		}
+
+		/*
+		 * We're truncating a file that used to have good data down to
+		 * zero. Make sure any new writes to the file get on disk
+		 * on close.
+		 */
+		if (newsize == 0)
+			set_bit(BTRFS_INODE_FLUSH_ON_CLOSE,
+				&BTRFS_I(inode)->runtime_flags);
+
+		truncate_setsize(inode, newsize);
+
+		inode_dio_wait(inode);
+
+		ret = btrfs_truncate(BTRFS_I(inode), newsize == oldsize);
+		if (ret && inode->i_nlink) {
+			int err;
+
+			/*
+			 * Truncate failed, so fix up the in-memory size. We
+			 * adjusted disk_i_size down as we removed extents, so
+			 * wait for disk_i_size to be stable and then update the
+			 * in-memory size to match.
+			 */
+			err = btrfs_wait_ordered_range(inode, 0, (u64)-1);
+			if (err)
+				return err;
+			i_size_write(inode, BTRFS_I(inode)->disk_i_size);
+		}
+	}
+
+	return ret;
+}
+
+static int btrfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+			 struct iattr *attr)
+{
+	struct inode *inode = d_inode(dentry);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int err;
+
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+
+	err = setattr_prepare(idmap, dentry, attr);
+	if (err)
+		return err;
+
+	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
+		err = btrfs_setsize(inode, attr);
+		if (err)
+			return err;
+	}
+
+	if (attr->ia_valid) {
+		setattr_copy(idmap, inode, attr);
+		inode_inc_iversion(inode);
+		err = btrfs_dirty_inode(BTRFS_I(inode));
+
+		if (!err && attr->ia_valid & ATTR_MODE)
+			err = posix_acl_chmod(idmap, dentry, inode->i_mode);
+	}
+
+	return err;
+}
+
+/*
+ * While truncating the inode pages during eviction, we get the VFS
+ * calling btrfs_invalidate_folio() against each folio of the inode. This
+ * is slow because the calls to btrfs_invalidate_folio() result in a
+ * huge amount of calls to lock_extent() and clear_extent_bit(),
+ * which keep merging and splitting extent_state structures over and over,
+ * wasting lots of time.
+ *
+ * Therefore if the inode is being evicted, let btrfs_invalidate_folio()
+ * skip all those expensive operations on a per folio basis and do only
+ * the ordered io finishing, while we release here the extent_map and
+ * extent_state structures, without the excessive merging and splitting.
+ */
+static void evict_inode_truncate_pages(struct inode *inode)
+{
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct rb_node *node;
+
+	ASSERT(inode->i_state & I_FREEING);
+	truncate_inode_pages_final(&inode->i_data);
+
+	btrfs_drop_extent_map_range(BTRFS_I(inode), 0, (u64)-1, false);
+
+	/*
+	 * Keep looping until we have no more ranges in the io tree.
+	 * We can have ongoing bios started by readahead that have
+	 * their endio callback (extent_io.c:end_bio_extent_readpage)
+	 * still in progress (unlocked the pages in the bio but did not yet
+	 * unlocked the ranges in the io tree). Therefore this means some
+	 * ranges can still be locked and eviction started because before
+	 * submitting those bios, which are executed by a separate task (work
+	 * queue kthread), inode references (inode->i_count) were not taken
+	 * (which would be dropped in the end io callback of each bio).
+	 * Therefore here we effectively end up waiting for those bios and
+	 * anyone else holding locked ranges without having bumped the inode's
+	 * reference count - if we don't do it, when they access the inode's
+	 * io_tree to unlock a range it may be too late, leading to an
+	 * use-after-free issue.
+	 */
+	spin_lock(&io_tree->lock);
+	while (!RB_EMPTY_ROOT(&io_tree->state)) {
+		struct extent_state *state;
+		struct extent_state *cached_state = NULL;
+		u64 start;
+		u64 end;
+		unsigned state_flags;
+
+		node = rb_first(&io_tree->state);
+		state = rb_entry(node, struct extent_state, rb_node);
+		start = state->start;
+		end = state->end;
+		state_flags = state->state;
+		spin_unlock(&io_tree->lock);
+
+		lock_extent(io_tree, start, end, &cached_state);
+
+		/*
+		 * If still has DELALLOC flag, the extent didn't reach disk,
+		 * and its reserved space won't be freed by delayed_ref.
+		 * So we need to free its reserved space here.
+		 * (Refer to comment in btrfs_invalidate_folio, case 2)
+		 *
+		 * Note, end is the bytenr of last byte, so we need + 1 here.
+		 */
+		if (state_flags & EXTENT_DELALLOC)
+			btrfs_qgroup_free_data(BTRFS_I(inode), NULL, start,
+					       end - start + 1, NULL);
+
+		clear_extent_bit(io_tree, start, end,
+				 EXTENT_CLEAR_ALL_BITS | EXTENT_DO_ACCOUNTING,
+				 &cached_state);
+
+		cond_resched();
+		spin_lock(&io_tree->lock);
+	}
+	spin_unlock(&io_tree->lock);
+}
+
+static struct btrfs_trans_handle *evict_refill_and_join(struct btrfs_root *root,
+							struct btrfs_block_rsv *rsv)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	u64 delayed_refs_extra = btrfs_calc_delayed_ref_bytes(fs_info, 1);
+	int ret;
+
+	/*
+	 * Eviction should be taking place at some place safe because of our
+	 * delayed iputs.  However the normal flushing code will run delayed
+	 * iputs, so we cannot use FLUSH_ALL otherwise we'll deadlock.
+	 *
+	 * We reserve the delayed_refs_extra here again because we can't use
+	 * btrfs_start_transaction(root, 0) for the same deadlocky reason as
+	 * above.  We reserve our extra bit here because we generate a ton of
+	 * delayed refs activity by truncating.
+	 *
+	 * BTRFS_RESERVE_FLUSH_EVICT will steal from the global_rsv if it can,
+	 * if we fail to make this reservation we can re-try without the
+	 * delayed_refs_extra so we can make some forward progress.
+	 */
+	ret = btrfs_block_rsv_refill(fs_info, rsv, rsv->size + delayed_refs_extra,
+				     BTRFS_RESERVE_FLUSH_EVICT);
+	if (ret) {
+		ret = btrfs_block_rsv_refill(fs_info, rsv, rsv->size,
+					     BTRFS_RESERVE_FLUSH_EVICT);
+		if (ret) {
+			btrfs_warn(fs_info,
+				   "could not allocate space for delete; will truncate on mount");
+			return ERR_PTR(-ENOSPC);
+		}
+		delayed_refs_extra = 0;
+	}
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans))
+		return trans;
+
+	if (delayed_refs_extra) {
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		trans->bytes_reserved = delayed_refs_extra;
+		btrfs_block_rsv_migrate(rsv, trans->block_rsv,
+					delayed_refs_extra, true);
+	}
+	return trans;
+}
+
+void btrfs_evict_inode(struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_block_rsv *rsv = NULL;
+	int ret;
+
+	trace_btrfs_inode_evict(inode);
+
+	if (!root) {
+		fsverity_cleanup_inode(inode);
+		clear_inode(inode);
+		return;
+	}
+
+	evict_inode_truncate_pages(inode);
+
+	if (inode->i_nlink &&
+	    ((btrfs_root_refs(&root->root_item) != 0 &&
+	      root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID) ||
+	     btrfs_is_free_space_inode(BTRFS_I(inode))))
+		goto out;
+
+	if (is_bad_inode(inode))
+		goto out;
+
+	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
+		goto out;
+
+	if (inode->i_nlink > 0) {
+		BUG_ON(btrfs_root_refs(&root->root_item) != 0 &&
+		       root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID);
+		goto out;
+	}
+
+	/*
+	 * This makes sure the inode item in tree is uptodate and the space for
+	 * the inode update is released.
+	 */
+	ret = btrfs_commit_inode_delayed_inode(BTRFS_I(inode));
+	if (ret)
+		goto out;
+
+	/*
+	 * This drops any pending insert or delete operations we have for this
+	 * inode.  We could have a delayed dir index deletion queued up, but
+	 * we're removing the inode completely so that'll be taken care of in
+	 * the truncate.
+	 */
+	btrfs_kill_delayed_inode_items(BTRFS_I(inode));
+
+	rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
+	if (!rsv)
+		goto out;
+	rsv->size = btrfs_calc_metadata_size(fs_info, 1);
+	rsv->failfast = true;
+
+	btrfs_i_size_write(BTRFS_I(inode), 0);
+
+	while (1) {
+		struct btrfs_truncate_control control = {
+			.inode = BTRFS_I(inode),
+			.ino = btrfs_ino(BTRFS_I(inode)),
+			.new_size = 0,
+			.min_type = 0,
+		};
+
+		trans = evict_refill_and_join(root, rsv);
+		if (IS_ERR(trans))
+			goto out;
+
+		trans->block_rsv = rsv;
+
+		ret = btrfs_truncate_inode_items(trans, root, &control);
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		btrfs_end_transaction(trans);
+		/*
+		 * We have not added new delayed items for our inode after we
+		 * have flushed its delayed items, so no need to throttle on
+		 * delayed items. However we have modified extent buffers.
+		 */
+		btrfs_btree_balance_dirty_nodelay(fs_info);
+		if (ret && ret != -ENOSPC && ret != -EAGAIN)
+			goto out;
+		else if (!ret)
+			break;
+	}
+
+	/*
+	 * Errors here aren't a big deal, it just means we leave orphan items in
+	 * the tree. They will be cleaned up on the next mount. If the inode
+	 * number gets reused, cleanup deletes the orphan item without doing
+	 * anything, and unlink reuses the existing orphan item.
+	 *
+	 * If it turns out that we are dropping too many of these, we might want
+	 * to add a mechanism for retrying these after a commit.
+	 */
+	trans = evict_refill_and_join(root, rsv);
+	if (!IS_ERR(trans)) {
+		trans->block_rsv = rsv;
+		btrfs_orphan_del(trans, BTRFS_I(inode));
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		btrfs_end_transaction(trans);
+	}
+
+out:
+	btrfs_free_block_rsv(fs_info, rsv);
+	/*
+	 * If we didn't successfully delete, the orphan item will still be in
+	 * the tree and we'll retry on the next mount. Again, we might also want
+	 * to retry these periodically in the future.
+	 */
+	btrfs_remove_delayed_node(BTRFS_I(inode));
+	fsverity_cleanup_inode(inode);
+	clear_inode(inode);
+}
+
+/*
+ * Return the key found in the dir entry in the location pointer, fill @type
+ * with BTRFS_FT_*, and return 0.
+ *
+ * If no dir entries were found, returns -ENOENT.
+ * If found a corrupted location in dir entry, returns -EUCLEAN.
+ */
+static int btrfs_inode_by_name(struct btrfs_inode *dir, struct dentry *dentry,
+			       struct btrfs_key *location, u8 *type)
+{
+	struct btrfs_dir_item *di;
+	struct btrfs_path *path;
+	struct btrfs_root *root = dir->root;
+	int ret = 0;
+	struct fscrypt_name fname;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = fscrypt_setup_filename(&dir->vfs_inode, &dentry->d_name, 1, &fname);
+	if (ret < 0)
+		goto out;
+	/*
+	 * fscrypt_setup_filename() should never return a positive value, but
+	 * gcc on sparc/parisc thinks it can, so assert that doesn't happen.
+	 */
+	ASSERT(ret == 0);
+
+	/* This needs to handle no-key deletions later on */
+
+	di = btrfs_lookup_dir_item(NULL, root, path, btrfs_ino(dir),
+				   &fname.disk_name, 0);
+	if (IS_ERR_OR_NULL(di)) {
+		ret = di ? PTR_ERR(di) : -ENOENT;
+		goto out;
+	}
+
+	btrfs_dir_item_key_to_cpu(path->nodes[0], di, location);
+	if (location->type != BTRFS_INODE_ITEM_KEY &&
+	    location->type != BTRFS_ROOT_ITEM_KEY) {
+		ret = -EUCLEAN;
+		btrfs_warn(root->fs_info,
+"%s gets something invalid in DIR_ITEM (name %s, directory ino %llu, location(%llu %u %llu))",
+			   __func__, fname.disk_name.name, btrfs_ino(dir),
+			   location->objectid, location->type, location->offset);
+	}
+	if (!ret)
+		*type = btrfs_dir_ftype(path->nodes[0], di);
+out:
+	fscrypt_free_filename(&fname);
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * when we hit a tree root in a directory, the btrfs part of the inode
+ * needs to be changed to reflect the root directory of the tree root.  This
+ * is kind of like crossing a mount point.
+ */
+static int fixup_tree_root_location(struct btrfs_fs_info *fs_info,
+				    struct btrfs_inode *dir,
+				    struct dentry *dentry,
+				    struct btrfs_key *location,
+				    struct btrfs_root **sub_root)
+{
+	struct btrfs_path *path;
+	struct btrfs_root *new_root;
+	struct btrfs_root_ref *ref;
+	struct extent_buffer *leaf;
+	struct btrfs_key key;
+	int ret;
+	int err = 0;
+	struct fscrypt_name fname;
+
+	ret = fscrypt_setup_filename(&dir->vfs_inode, &dentry->d_name, 0, &fname);
+	if (ret)
+		return ret;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	err = -ENOENT;
+	key.objectid = dir->root->root_key.objectid;
+	key.type = BTRFS_ROOT_REF_KEY;
+	key.offset = location->objectid;
+
+	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
+	if (ret) {
+		if (ret < 0)
+			err = ret;
+		goto out;
+	}
+
+	leaf = path->nodes[0];
+	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
+	if (btrfs_root_ref_dirid(leaf, ref) != btrfs_ino(dir) ||
+	    btrfs_root_ref_name_len(leaf, ref) != fname.disk_name.len)
+		goto out;
+
+	ret = memcmp_extent_buffer(leaf, fname.disk_name.name,
+				   (unsigned long)(ref + 1), fname.disk_name.len);
+	if (ret)
+		goto out;
+
+	btrfs_release_path(path);
+
+	new_root = btrfs_get_fs_root(fs_info, location->objectid, true);
+	if (IS_ERR(new_root)) {
+		err = PTR_ERR(new_root);
+		goto out;
+	}
+
+	*sub_root = new_root;
+	location->objectid = btrfs_root_dirid(&new_root->root_item);
+	location->type = BTRFS_INODE_ITEM_KEY;
+	location->offset = 0;
+	err = 0;
+out:
+	btrfs_free_path(path);
+	fscrypt_free_filename(&fname);
+	return err;
+}
+
+static void inode_tree_add(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_inode *entry;
+	struct rb_node **p;
+	struct rb_node *parent;
+	struct rb_node *new = &inode->rb_node;
+	u64 ino = btrfs_ino(inode);
+
+	if (inode_unhashed(&inode->vfs_inode))
+		return;
+	parent = NULL;
+	spin_lock(&root->inode_lock);
+	p = &root->inode_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct btrfs_inode, rb_node);
+
+		if (ino < btrfs_ino(entry))
+			p = &parent->rb_left;
+		else if (ino > btrfs_ino(entry))
+			p = &parent->rb_right;
+		else {
+			WARN_ON(!(entry->vfs_inode.i_state &
+				  (I_WILL_FREE | I_FREEING)));
+			rb_replace_node(parent, new, &root->inode_tree);
+			RB_CLEAR_NODE(parent);
+			spin_unlock(&root->inode_lock);
+			return;
+		}
+	}
+	rb_link_node(new, parent, p);
+	rb_insert_color(new, &root->inode_tree);
+	spin_unlock(&root->inode_lock);
+}
+
+static void inode_tree_del(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	int empty = 0;
+
+	spin_lock(&root->inode_lock);
+	if (!RB_EMPTY_NODE(&inode->rb_node)) {
+		rb_erase(&inode->rb_node, &root->inode_tree);
+		RB_CLEAR_NODE(&inode->rb_node);
+		empty = RB_EMPTY_ROOT(&root->inode_tree);
+	}
+	spin_unlock(&root->inode_lock);
+
+	if (empty && btrfs_root_refs(&root->root_item) == 0) {
+		spin_lock(&root->inode_lock);
+		empty = RB_EMPTY_ROOT(&root->inode_tree);
+		spin_unlock(&root->inode_lock);
+		if (empty)
+			btrfs_add_dead_root(root);
+	}
+}
+
+
+static int btrfs_init_locked_inode(struct inode *inode, void *p)
+{
+	struct btrfs_iget_args *args = p;
+
+	inode->i_ino = args->ino;
+	BTRFS_I(inode)->location.objectid = args->ino;
+	BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY;
+	BTRFS_I(inode)->location.offset = 0;
+	BTRFS_I(inode)->root = btrfs_grab_root(args->root);
+	BUG_ON(args->root && !BTRFS_I(inode)->root);
+
+	if (args->root && args->root == args->root->fs_info->tree_root &&
+	    args->ino != BTRFS_BTREE_INODE_OBJECTID)
+		set_bit(BTRFS_INODE_FREE_SPACE_INODE,
+			&BTRFS_I(inode)->runtime_flags);
+	return 0;
+}
+
+static int btrfs_find_actor(struct inode *inode, void *opaque)
+{
+	struct btrfs_iget_args *args = opaque;
+
+	return args->ino == BTRFS_I(inode)->location.objectid &&
+		args->root == BTRFS_I(inode)->root;
+}
+
+static struct inode *btrfs_iget_locked(struct super_block *s, u64 ino,
+				       struct btrfs_root *root)
+{
+	struct inode *inode;
+	struct btrfs_iget_args args;
+	unsigned long hashval = btrfs_inode_hash(ino, root);
+
+	args.ino = ino;
+	args.root = root;
+
+	inode = iget5_locked(s, hashval, btrfs_find_actor,
+			     btrfs_init_locked_inode,
+			     (void *)&args);
+	return inode;
+}
+
+/*
+ * Get an inode object given its inode number and corresponding root.
+ * Path can be preallocated to prevent recursing back to iget through
+ * allocator. NULL is also valid but may require an additional allocation
+ * later.
+ */
+struct inode *btrfs_iget_path(struct super_block *s, u64 ino,
+			      struct btrfs_root *root, struct btrfs_path *path)
+{
+	struct inode *inode;
+
+	inode = btrfs_iget_locked(s, ino, root);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	if (inode->i_state & I_NEW) {
+		int ret;
+
+		ret = btrfs_read_locked_inode(inode, path);
+		if (!ret) {
+			inode_tree_add(BTRFS_I(inode));
+			unlock_new_inode(inode);
+		} else {
+			iget_failed(inode);
+			/*
+			 * ret > 0 can come from btrfs_search_slot called by
+			 * btrfs_read_locked_inode, this means the inode item
+			 * was not found.
+			 */
+			if (ret > 0)
+				ret = -ENOENT;
+			inode = ERR_PTR(ret);
+		}
+	}
+
+	return inode;
+}
+
+struct inode *btrfs_iget(struct super_block *s, u64 ino, struct btrfs_root *root)
+{
+	return btrfs_iget_path(s, ino, root, NULL);
+}
+
+static struct inode *new_simple_dir(struct inode *dir,
+				    struct btrfs_key *key,
+				    struct btrfs_root *root)
+{
+	struct inode *inode = new_inode(dir->i_sb);
+
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	BTRFS_I(inode)->root = btrfs_grab_root(root);
+	memcpy(&BTRFS_I(inode)->location, key, sizeof(*key));
+	set_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags);
+
+	inode->i_ino = BTRFS_EMPTY_SUBVOL_DIR_OBJECTID;
+	/*
+	 * We only need lookup, the rest is read-only and there's no inode
+	 * associated with the dentry
+	 */
+	inode->i_op = &simple_dir_inode_operations;
+	inode->i_opflags &= ~IOP_XATTR;
+	inode->i_fop = &simple_dir_operations;
+	inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;
+	inode->i_mtime = inode_set_ctime_current(inode);
+	inode->i_atime = dir->i_atime;
+	BTRFS_I(inode)->i_otime = inode->i_mtime;
+	inode->i_uid = dir->i_uid;
+	inode->i_gid = dir->i_gid;
+
+	return inode;
+}
+
+static_assert(BTRFS_FT_UNKNOWN == FT_UNKNOWN);
+static_assert(BTRFS_FT_REG_FILE == FT_REG_FILE);
+static_assert(BTRFS_FT_DIR == FT_DIR);
+static_assert(BTRFS_FT_CHRDEV == FT_CHRDEV);
+static_assert(BTRFS_FT_BLKDEV == FT_BLKDEV);
+static_assert(BTRFS_FT_FIFO == FT_FIFO);
+static_assert(BTRFS_FT_SOCK == FT_SOCK);
+static_assert(BTRFS_FT_SYMLINK == FT_SYMLINK);
+
+static inline u8 btrfs_inode_type(struct inode *inode)
+{
+	return fs_umode_to_ftype(inode->i_mode);
+}
+
+struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
+	struct inode *inode;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_root *sub_root = root;
+	struct btrfs_key location;
+	u8 di_type = 0;
+	int ret = 0;
+
+	if (dentry->d_name.len > BTRFS_NAME_LEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	ret = btrfs_inode_by_name(BTRFS_I(dir), dentry, &location, &di_type);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (location.type == BTRFS_INODE_ITEM_KEY) {
+		inode = btrfs_iget(dir->i_sb, location.objectid, root);
+		if (IS_ERR(inode))
+			return inode;
+
+		/* Do extra check against inode mode with di_type */
+		if (btrfs_inode_type(inode) != di_type) {
+			btrfs_crit(fs_info,
+"inode mode mismatch with dir: inode mode=0%o btrfs type=%u dir type=%u",
+				  inode->i_mode, btrfs_inode_type(inode),
+				  di_type);
+			iput(inode);
+			return ERR_PTR(-EUCLEAN);
+		}
+		return inode;
+	}
+
+	ret = fixup_tree_root_location(fs_info, BTRFS_I(dir), dentry,
+				       &location, &sub_root);
+	if (ret < 0) {
+		if (ret != -ENOENT)
+			inode = ERR_PTR(ret);
+		else
+			inode = new_simple_dir(dir, &location, root);
+	} else {
+		inode = btrfs_iget(dir->i_sb, location.objectid, sub_root);
+		btrfs_put_root(sub_root);
+
+		if (IS_ERR(inode))
+			return inode;
+
+		down_read(&fs_info->cleanup_work_sem);
+		if (!sb_rdonly(inode->i_sb))
+			ret = btrfs_orphan_cleanup(sub_root);
+		up_read(&fs_info->cleanup_work_sem);
+		if (ret) {
+			iput(inode);
+			inode = ERR_PTR(ret);
+		}
+	}
+
+	return inode;
+}
+
+static int btrfs_dentry_delete(const struct dentry *dentry)
+{
+	struct btrfs_root *root;
+	struct inode *inode = d_inode(dentry);
+
+	if (!inode && !IS_ROOT(dentry))
+		inode = d_inode(dentry->d_parent);
+
+	if (inode) {
+		root = BTRFS_I(inode)->root;
+		if (btrfs_root_refs(&root->root_item) == 0)
+			return 1;
+
+		if (btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
+			return 1;
+	}
+	return 0;
+}
+
+static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
+				   unsigned int flags)
+{
+	struct inode *inode = btrfs_lookup_dentry(dir, dentry);
+
+	if (inode == ERR_PTR(-ENOENT))
+		inode = NULL;
+	return d_splice_alias(inode, dentry);
+}
+
+/*
+ * Find the highest existing sequence number in a directory and then set the
+ * in-memory index_cnt variable to the first free sequence number.
+ */
+static int btrfs_set_inode_index_count(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_key key, found_key;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	int ret;
+
+	key.objectid = btrfs_ino(inode);
+	key.type = BTRFS_DIR_INDEX_KEY;
+	key.offset = (u64)-1;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+	/* FIXME: we should be able to handle this */
+	if (ret == 0)
+		goto out;
+	ret = 0;
+
+	if (path->slots[0] == 0) {
+		inode->index_cnt = BTRFS_DIR_START_INDEX;
+		goto out;
+	}
+
+	path->slots[0]--;
+
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+	if (found_key.objectid != btrfs_ino(inode) ||
+	    found_key.type != BTRFS_DIR_INDEX_KEY) {
+		inode->index_cnt = BTRFS_DIR_START_INDEX;
+		goto out;
+	}
+
+	inode->index_cnt = found_key.offset + 1;
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static int btrfs_get_dir_last_index(struct btrfs_inode *dir, u64 *index)
+{
+	int ret = 0;
+
+	btrfs_inode_lock(dir, 0);
+	if (dir->index_cnt == (u64)-1) {
+		ret = btrfs_inode_delayed_dir_index_count(dir);
+		if (ret) {
+			ret = btrfs_set_inode_index_count(dir);
+			if (ret)
+				goto out;
+		}
+	}
+
+	/* index_cnt is the index number of next new entry, so decrement it. */
+	*index = dir->index_cnt - 1;
+out:
+	btrfs_inode_unlock(dir, 0);
+
+	return ret;
+}
+
+/*
+ * All this infrastructure exists because dir_emit can fault, and we are holding
+ * the tree lock when doing readdir.  For now just allocate a buffer and copy
+ * our information into that, and then dir_emit from the buffer.  This is
+ * similar to what NFS does, only we don't keep the buffer around in pagecache
+ * because I'm afraid I'll mess that up.  Long term we need to make filldir do
+ * copy_to_user_inatomic so we don't have to worry about page faulting under the
+ * tree lock.
+ */
+static int btrfs_opendir(struct inode *inode, struct file *file)
+{
+	struct btrfs_file_private *private;
+	u64 last_index;
+	int ret;
+
+	ret = btrfs_get_dir_last_index(BTRFS_I(inode), &last_index);
+	if (ret)
+		return ret;
+
+	private = kzalloc(sizeof(struct btrfs_file_private), GFP_KERNEL);
+	if (!private)
+		return -ENOMEM;
+	private->last_index = last_index;
+	private->filldir_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!private->filldir_buf) {
+		kfree(private);
+		return -ENOMEM;
+	}
+	file->private_data = private;
+	return 0;
+}
+
+static loff_t btrfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct btrfs_file_private *private = file->private_data;
+	int ret;
+
+	ret = btrfs_get_dir_last_index(BTRFS_I(file_inode(file)),
+				       &private->last_index);
+	if (ret)
+		return ret;
+
+	return generic_file_llseek(file, offset, whence);
+}
+
+struct dir_entry {
+	u64 ino;
+	u64 offset;
+	unsigned type;
+	int name_len;
+};
+
+static int btrfs_filldir(void *addr, int entries, struct dir_context *ctx)
+{
+	while (entries--) {
+		struct dir_entry *entry = addr;
+		char *name = (char *)(entry + 1);
+
+		ctx->pos = get_unaligned(&entry->offset);
+		if (!dir_emit(ctx, name, get_unaligned(&entry->name_len),
+					 get_unaligned(&entry->ino),
+					 get_unaligned(&entry->type)))
+			return 1;
+		addr += sizeof(struct dir_entry) +
+			get_unaligned(&entry->name_len);
+		ctx->pos++;
+	}
+	return 0;
+}
+
+static int btrfs_real_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_file_private *private = file->private_data;
+	struct btrfs_dir_item *di;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	struct btrfs_path *path;
+	void *addr;
+	LIST_HEAD(ins_list);
+	LIST_HEAD(del_list);
+	int ret;
+	char *name_ptr;
+	int name_len;
+	int entries = 0;
+	int total_len = 0;
+	bool put = false;
+	struct btrfs_key location;
+
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	addr = private->filldir_buf;
+	path->reada = READA_FORWARD;
+
+	put = btrfs_readdir_get_delayed_items(inode, private->last_index,
+					      &ins_list, &del_list);
+
+again:
+	key.type = BTRFS_DIR_INDEX_KEY;
+	key.offset = ctx->pos;
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+
+	btrfs_for_each_slot(root, &key, &found_key, path, ret) {
+		struct dir_entry *entry;
+		struct extent_buffer *leaf = path->nodes[0];
+		u8 ftype;
+
+		if (found_key.objectid != key.objectid)
+			break;
+		if (found_key.type != BTRFS_DIR_INDEX_KEY)
+			break;
+		if (found_key.offset < ctx->pos)
+			continue;
+		if (found_key.offset > private->last_index)
+			break;
+		if (btrfs_should_delete_dir_index(&del_list, found_key.offset))
+			continue;
+		di = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
+		name_len = btrfs_dir_name_len(leaf, di);
+		if ((total_len + sizeof(struct dir_entry) + name_len) >=
+		    PAGE_SIZE) {
+			btrfs_release_path(path);
+			ret = btrfs_filldir(private->filldir_buf, entries, ctx);
+			if (ret)
+				goto nopos;
+			addr = private->filldir_buf;
+			entries = 0;
+			total_len = 0;
+			goto again;
+		}
+
+		ftype = btrfs_dir_flags_to_ftype(btrfs_dir_flags(leaf, di));
+		entry = addr;
+		name_ptr = (char *)(entry + 1);
+		read_extent_buffer(leaf, name_ptr,
+				   (unsigned long)(di + 1), name_len);
+		put_unaligned(name_len, &entry->name_len);
+		put_unaligned(fs_ftype_to_dtype(ftype), &entry->type);
+		btrfs_dir_item_key_to_cpu(leaf, di, &location);
+		put_unaligned(location.objectid, &entry->ino);
+		put_unaligned(found_key.offset, &entry->offset);
+		entries++;
+		addr += sizeof(struct dir_entry) + name_len;
+		total_len += sizeof(struct dir_entry) + name_len;
+	}
+	/* Catch error encountered during iteration */
+	if (ret < 0)
+		goto err;
+
+	btrfs_release_path(path);
+
+	ret = btrfs_filldir(private->filldir_buf, entries, ctx);
+	if (ret)
+		goto nopos;
+
+	ret = btrfs_readdir_delayed_dir_index(ctx, &ins_list);
+	if (ret)
+		goto nopos;
+
+	/*
+	 * Stop new entries from being returned after we return the last
+	 * entry.
+	 *
+	 * New directory entries are assigned a strictly increasing
+	 * offset.  This means that new entries created during readdir
+	 * are *guaranteed* to be seen in the future by that readdir.
+	 * This has broken buggy programs which operate on names as
+	 * they're returned by readdir.  Until we re-use freed offsets
+	 * we have this hack to stop new entries from being returned
+	 * under the assumption that they'll never reach this huge
+	 * offset.
+	 *
+	 * This is being careful not to overflow 32bit loff_t unless the
+	 * last entry requires it because doing so has broken 32bit apps
+	 * in the past.
+	 */
+	if (ctx->pos >= INT_MAX)
+		ctx->pos = LLONG_MAX;
+	else
+		ctx->pos = INT_MAX;
+nopos:
+	ret = 0;
+err:
+	if (put)
+		btrfs_readdir_put_delayed_items(inode, &ins_list, &del_list);
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * This is somewhat expensive, updating the tree every time the
+ * inode changes.  But, it is most likely to find the inode in cache.
+ * FIXME, needs more benchmarking...there are no reasons other than performance
+ * to keep or drop this code.
+ */
+static int btrfs_dirty_inode(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	if (test_bit(BTRFS_INODE_DUMMY, &inode->runtime_flags))
+		return 0;
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	ret = btrfs_update_inode(trans, root, inode);
+	if (ret && (ret == -ENOSPC || ret == -EDQUOT)) {
+		/* whoops, lets try again with the full transaction */
+		btrfs_end_transaction(trans);
+		trans = btrfs_start_transaction(root, 1);
+		if (IS_ERR(trans))
+			return PTR_ERR(trans);
+
+		ret = btrfs_update_inode(trans, root, inode);
+	}
+	btrfs_end_transaction(trans);
+	if (inode->delayed_node)
+		btrfs_balance_delayed_items(fs_info);
+
+	return ret;
+}
+
+/*
+ * This is a copy of file_update_time.  We need this so we can return error on
+ * ENOSPC for updating the inode in the case of file write and mmap writes.
+ */
+static int btrfs_update_time(struct inode *inode, int flags)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	bool dirty = flags & ~S_VERSION;
+
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+
+	dirty = inode_update_timestamps(inode, flags);
+	return dirty ? btrfs_dirty_inode(BTRFS_I(inode)) : 0;
+}
+
+/*
+ * helper to find a free sequence number in a given directory.  This current
+ * code is very simple, later versions will do smarter things in the btree
+ */
+int btrfs_set_inode_index(struct btrfs_inode *dir, u64 *index)
+{
+	int ret = 0;
+
+	if (dir->index_cnt == (u64)-1) {
+		ret = btrfs_inode_delayed_dir_index_count(dir);
+		if (ret) {
+			ret = btrfs_set_inode_index_count(dir);
+			if (ret)
+				return ret;
+		}
+	}
+
+	*index = dir->index_cnt;
+	dir->index_cnt++;
+
+	return ret;
+}
+
+static int btrfs_insert_inode_locked(struct inode *inode)
+{
+	struct btrfs_iget_args args;
+
+	args.ino = BTRFS_I(inode)->location.objectid;
+	args.root = BTRFS_I(inode)->root;
+
+	return insert_inode_locked4(inode,
+		   btrfs_inode_hash(inode->i_ino, BTRFS_I(inode)->root),
+		   btrfs_find_actor, &args);
+}
+
+int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
+			    unsigned int *trans_num_items)
+{
+	struct inode *dir = args->dir;
+	struct inode *inode = args->inode;
+	int ret;
+
+	if (!args->orphan) {
+		ret = fscrypt_setup_filename(dir, &args->dentry->d_name, 0,
+					     &args->fname);
+		if (ret)
+			return ret;
+	}
+
+	ret = posix_acl_create(dir, &inode->i_mode, &args->default_acl, &args->acl);
+	if (ret) {
+		fscrypt_free_filename(&args->fname);
+		return ret;
+	}
+
+	/* 1 to add inode item */
+	*trans_num_items = 1;
+	/* 1 to add compression property */
+	if (BTRFS_I(dir)->prop_compress)
+		(*trans_num_items)++;
+	/* 1 to add default ACL xattr */
+	if (args->default_acl)
+		(*trans_num_items)++;
+	/* 1 to add access ACL xattr */
+	if (args->acl)
+		(*trans_num_items)++;
+#ifdef CONFIG_SECURITY
+	/* 1 to add LSM xattr */
+	if (dir->i_security)
+		(*trans_num_items)++;
+#endif
+	if (args->orphan) {
+		/* 1 to add orphan item */
+		(*trans_num_items)++;
+	} else {
+		/*
+		 * 1 to add dir item
+		 * 1 to add dir index
+		 * 1 to update parent inode item
+		 *
+		 * No need for 1 unit for the inode ref item because it is
+		 * inserted in a batch together with the inode item at
+		 * btrfs_create_new_inode().
+		 */
+		*trans_num_items += 3;
+	}
+	return 0;
+}
+
+void btrfs_new_inode_args_destroy(struct btrfs_new_inode_args *args)
+{
+	posix_acl_release(args->acl);
+	posix_acl_release(args->default_acl);
+	fscrypt_free_filename(&args->fname);
+}
+
+/*
+ * Inherit flags from the parent inode.
+ *
+ * Currently only the compression flags and the cow flags are inherited.
+ */
+static void btrfs_inherit_iflags(struct btrfs_inode *inode, struct btrfs_inode *dir)
+{
+	unsigned int flags;
+
+	flags = dir->flags;
+
+	if (flags & BTRFS_INODE_NOCOMPRESS) {
+		inode->flags &= ~BTRFS_INODE_COMPRESS;
+		inode->flags |= BTRFS_INODE_NOCOMPRESS;
+	} else if (flags & BTRFS_INODE_COMPRESS) {
+		inode->flags &= ~BTRFS_INODE_NOCOMPRESS;
+		inode->flags |= BTRFS_INODE_COMPRESS;
+	}
+
+	if (flags & BTRFS_INODE_NODATACOW) {
+		inode->flags |= BTRFS_INODE_NODATACOW;
+		if (S_ISREG(inode->vfs_inode.i_mode))
+			inode->flags |= BTRFS_INODE_NODATASUM;
+	}
+
+	btrfs_sync_inode_flags_to_i_flags(&inode->vfs_inode);
+}
+
+int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
+			   struct btrfs_new_inode_args *args)
+{
+	struct inode *dir = args->dir;
+	struct inode *inode = args->inode;
+	const struct fscrypt_str *name = args->orphan ? NULL : &args->fname.disk_name;
+	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
+	struct btrfs_root *root;
+	struct btrfs_inode_item *inode_item;
+	struct btrfs_key *location;
+	struct btrfs_path *path;
+	u64 objectid;
+	struct btrfs_inode_ref *ref;
+	struct btrfs_key key[2];
+	u32 sizes[2];
+	struct btrfs_item_batch batch;
+	unsigned long ptr;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	if (!args->subvol)
+		BTRFS_I(inode)->root = btrfs_grab_root(BTRFS_I(dir)->root);
+	root = BTRFS_I(inode)->root;
+
+	ret = btrfs_get_free_objectid(root, &objectid);
+	if (ret)
+		goto out;
+	inode->i_ino = objectid;
+
+	if (args->orphan) {
+		/*
+		 * O_TMPFILE, set link count to 0, so that after this point, we
+		 * fill in an inode item with the correct link count.
+		 */
+		set_nlink(inode, 0);
+	} else {
+		trace_btrfs_inode_request(dir);
+
+		ret = btrfs_set_inode_index(BTRFS_I(dir), &BTRFS_I(inode)->dir_index);
+		if (ret)
+			goto out;
+	}
+	/* index_cnt is ignored for everything but a dir. */
+	BTRFS_I(inode)->index_cnt = BTRFS_DIR_START_INDEX;
+	BTRFS_I(inode)->generation = trans->transid;
+	inode->i_generation = BTRFS_I(inode)->generation;
+
+	/*
+	 * Subvolumes don't inherit flags from their parent directory.
+	 * Originally this was probably by accident, but we probably can't
+	 * change it now without compatibility issues.
+	 */
+	if (!args->subvol)
+		btrfs_inherit_iflags(BTRFS_I(inode), BTRFS_I(dir));
+
+	if (S_ISREG(inode->i_mode)) {
+		if (btrfs_test_opt(fs_info, NODATASUM))
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
+		if (btrfs_test_opt(fs_info, NODATACOW))
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW |
+				BTRFS_INODE_NODATASUM;
+	}
+
+	location = &BTRFS_I(inode)->location;
+	location->objectid = objectid;
+	location->offset = 0;
+	location->type = BTRFS_INODE_ITEM_KEY;
+
+	ret = btrfs_insert_inode_locked(inode);
+	if (ret < 0) {
+		if (!args->orphan)
+			BTRFS_I(dir)->index_cnt--;
+		goto out;
+	}
+
+	/*
+	 * We could have gotten an inode number from somebody who was fsynced
+	 * and then removed in this same transaction, so let's just set full
+	 * sync since it will be a full sync anyway and this will blow away the
+	 * old info in the log.
+	 */
+	btrfs_set_inode_full_sync(BTRFS_I(inode));
+
+	key[0].objectid = objectid;
+	key[0].type = BTRFS_INODE_ITEM_KEY;
+	key[0].offset = 0;
+
+	sizes[0] = sizeof(struct btrfs_inode_item);
+
+	if (!args->orphan) {
+		/*
+		 * Start new inodes with an inode_ref. This is slightly more
+		 * efficient for small numbers of hard links since they will
+		 * be packed into one item. Extended refs will kick in if we
+		 * add more hard links than can fit in the ref item.
+		 */
+		key[1].objectid = objectid;
+		key[1].type = BTRFS_INODE_REF_KEY;
+		if (args->subvol) {
+			key[1].offset = objectid;
+			sizes[1] = 2 + sizeof(*ref);
+		} else {
+			key[1].offset = btrfs_ino(BTRFS_I(dir));
+			sizes[1] = name->len + sizeof(*ref);
+		}
+	}
+
+	batch.keys = &key[0];
+	batch.data_sizes = &sizes[0];
+	batch.total_data_size = sizes[0] + (args->orphan ? 0 : sizes[1]);
+	batch.nr = args->orphan ? 1 : 2;
+	ret = btrfs_insert_empty_items(trans, root, path, &batch);
+	if (ret != 0) {
+		btrfs_abort_transaction(trans, ret);
+		goto discard;
+	}
+
+	inode->i_mtime = inode_set_ctime_current(inode);
+	inode->i_atime = inode->i_mtime;
+	BTRFS_I(inode)->i_otime = inode->i_mtime;
+
+	/*
+	 * We're going to fill the inode item now, so at this point the inode
+	 * must be fully initialized.
+	 */
+
+	inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				  struct btrfs_inode_item);
+	memzero_extent_buffer(path->nodes[0], (unsigned long)inode_item,
+			     sizeof(*inode_item));
+	fill_inode_item(trans, path->nodes[0], inode_item, inode);
+
+	if (!args->orphan) {
+		ref = btrfs_item_ptr(path->nodes[0], path->slots[0] + 1,
+				     struct btrfs_inode_ref);
+		ptr = (unsigned long)(ref + 1);
+		if (args->subvol) {
+			btrfs_set_inode_ref_name_len(path->nodes[0], ref, 2);
+			btrfs_set_inode_ref_index(path->nodes[0], ref, 0);
+			write_extent_buffer(path->nodes[0], "..", ptr, 2);
+		} else {
+			btrfs_set_inode_ref_name_len(path->nodes[0], ref,
+						     name->len);
+			btrfs_set_inode_ref_index(path->nodes[0], ref,
+						  BTRFS_I(inode)->dir_index);
+			write_extent_buffer(path->nodes[0], name->name, ptr,
+					    name->len);
+		}
+	}
+
+	btrfs_mark_buffer_dirty(trans, path->nodes[0]);
+	/*
+	 * We don't need the path anymore, plus inheriting properties, adding
+	 * ACLs, security xattrs, orphan item or adding the link, will result in
+	 * allocating yet another path. So just free our path.
+	 */
+	btrfs_free_path(path);
+	path = NULL;
+
+	if (args->subvol) {
+		struct inode *parent;
+
+		/*
+		 * Subvolumes inherit properties from their parent subvolume,
+		 * not the directory they were created in.
+		 */
+		parent = btrfs_iget(fs_info->sb, BTRFS_FIRST_FREE_OBJECTID,
+				    BTRFS_I(dir)->root);
+		if (IS_ERR(parent)) {
+			ret = PTR_ERR(parent);
+		} else {
+			ret = btrfs_inode_inherit_props(trans, inode, parent);
+			iput(parent);
+		}
+	} else {
+		ret = btrfs_inode_inherit_props(trans, inode, dir);
+	}
+	if (ret) {
+		btrfs_err(fs_info,
+			  "error inheriting props for ino %llu (root %llu): %d",
+			  btrfs_ino(BTRFS_I(inode)), root->root_key.objectid,
+			  ret);
+	}
+
+	/*
+	 * Subvolumes don't inherit ACLs or get passed to the LSM. This is
+	 * probably a bug.
+	 */
+	if (!args->subvol) {
+		ret = btrfs_init_inode_security(trans, args);
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			goto discard;
+		}
+	}
+
+	inode_tree_add(BTRFS_I(inode));
+
+	trace_btrfs_inode_new(inode);
+	btrfs_set_inode_last_trans(trans, BTRFS_I(inode));
+
+	btrfs_update_root_times(trans, root);
+
+	if (args->orphan) {
+		ret = btrfs_orphan_add(trans, BTRFS_I(inode));
+	} else {
+		ret = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode), name,
+				     0, BTRFS_I(inode)->dir_index);
+	}
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto discard;
+	}
+
+	return 0;
+
+discard:
+	/*
+	 * discard_new_inode() calls iput(), but the caller owns the reference
+	 * to the inode.
+	 */
+	ihold(inode);
+	discard_new_inode(inode);
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * utility function to add 'inode' into 'parent_inode' with
+ * a give name and a given sequence number.
+ * if 'add_backref' is true, also insert a backref from the
+ * inode to the parent directory.
+ */
+int btrfs_add_link(struct btrfs_trans_handle *trans,
+		   struct btrfs_inode *parent_inode, struct btrfs_inode *inode,
+		   const struct fscrypt_str *name, int add_backref, u64 index)
+{
+	int ret = 0;
+	struct btrfs_key key;
+	struct btrfs_root *root = parent_inode->root;
+	u64 ino = btrfs_ino(inode);
+	u64 parent_ino = btrfs_ino(parent_inode);
+
+	if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		memcpy(&key, &inode->root->root_key, sizeof(key));
+	} else {
+		key.objectid = ino;
+		key.type = BTRFS_INODE_ITEM_KEY;
+		key.offset = 0;
+	}
+
+	if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		ret = btrfs_add_root_ref(trans, key.objectid,
+					 root->root_key.objectid, parent_ino,
+					 index, name);
+	} else if (add_backref) {
+		ret = btrfs_insert_inode_ref(trans, root, name,
+					     ino, parent_ino, index);
+	}
+
+	/* Nothing to clean up yet */
+	if (ret)
+		return ret;
+
+	ret = btrfs_insert_dir_item(trans, name, parent_inode, &key,
+				    btrfs_inode_type(&inode->vfs_inode), index);
+	if (ret == -EEXIST || ret == -EOVERFLOW)
+		goto fail_dir_item;
+	else if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+
+	btrfs_i_size_write(parent_inode, parent_inode->vfs_inode.i_size +
+			   name->len * 2);
+	inode_inc_iversion(&parent_inode->vfs_inode);
+	/*
+	 * If we are replaying a log tree, we do not want to update the mtime
+	 * and ctime of the parent directory with the current time, since the
+	 * log replay procedure is responsible for setting them to their correct
+	 * values (the ones it had when the fsync was done).
+	 */
+	if (!test_bit(BTRFS_FS_LOG_RECOVERING, &root->fs_info->flags))
+		parent_inode->vfs_inode.i_mtime =
+			inode_set_ctime_current(&parent_inode->vfs_inode);
+
+	ret = btrfs_update_inode(trans, root, parent_inode);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+	return ret;
+
+fail_dir_item:
+	if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		u64 local_index;
+		int err;
+		err = btrfs_del_root_ref(trans, key.objectid,
+					 root->root_key.objectid, parent_ino,
+					 &local_index, name);
+		if (err)
+			btrfs_abort_transaction(trans, err);
+	} else if (add_backref) {
+		u64 local_index;
+		int err;
+
+		err = btrfs_del_inode_ref(trans, root, name, ino, parent_ino,
+					  &local_index);
+		if (err)
+			btrfs_abort_transaction(trans, err);
+	}
+
+	/* Return the original error code */
+	return ret;
+}
+
+static int btrfs_create_common(struct inode *dir, struct dentry *dentry,
+			       struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = dentry,
+		.inode = inode,
+	};
+	unsigned int trans_num_items;
+	struct btrfs_trans_handle *trans;
+	int err;
+
+	err = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (err)
+		goto out_inode;
+
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		err = PTR_ERR(trans);
+		goto out_new_inode_args;
+	}
+
+	err = btrfs_create_new_inode(trans, &new_inode_args);
+	if (!err)
+		d_instantiate_new(dentry, inode);
+
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
+out_inode:
+	if (err)
+		iput(inode);
+	return err;
+}
+
+static int btrfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
+		       struct dentry *dentry, umode_t mode, dev_t rdev)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, mode);
+	inode->i_op = &btrfs_special_inode_operations;
+	init_special_inode(inode, inode->i_mode, rdev);
+	return btrfs_create_common(dir, dentry, inode);
+}
+
+static int btrfs_create(struct mnt_idmap *idmap, struct inode *dir,
+			struct dentry *dentry, umode_t mode, bool excl)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, mode);
+	inode->i_fop = &btrfs_file_operations;
+	inode->i_op = &btrfs_file_inode_operations;
+	inode->i_mapping->a_ops = &btrfs_aops;
+	return btrfs_create_common(dir, dentry, inode);
+}
+
+static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
+		      struct dentry *dentry)
+{
+	struct btrfs_trans_handle *trans = NULL;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct inode *inode = d_inode(old_dentry);
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct fscrypt_name fname;
+	u64 index;
+	int err;
+	int drop_inode = 0;
+
+	/* do not allow sys_link's with other subvols of the same device */
+	if (root->root_key.objectid != BTRFS_I(inode)->root->root_key.objectid)
+		return -EXDEV;
+
+	if (inode->i_nlink >= BTRFS_LINK_MAX)
+		return -EMLINK;
+
+	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &fname);
+	if (err)
+		goto fail;
+
+	err = btrfs_set_inode_index(BTRFS_I(dir), &index);
+	if (err)
+		goto fail;
+
+	/*
+	 * 2 items for inode and inode ref
+	 * 2 items for dir items
+	 * 1 item for parent inode
+	 * 1 item for orphan item deletion if O_TMPFILE
+	 */
+	trans = btrfs_start_transaction(root, inode->i_nlink ? 5 : 6);
+	if (IS_ERR(trans)) {
+		err = PTR_ERR(trans);
+		trans = NULL;
+		goto fail;
+	}
+
+	/* There are several dir indexes for this inode, clear the cache. */
+	BTRFS_I(inode)->dir_index = 0ULL;
+	inc_nlink(inode);
+	inode_inc_iversion(inode);
+	inode_set_ctime_current(inode);
+	ihold(inode);
+	set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
+
+	err = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode),
+			     &fname.disk_name, 1, index);
+
+	if (err) {
+		drop_inode = 1;
+	} else {
+		struct dentry *parent = dentry->d_parent;
+
+		err = btrfs_update_inode(trans, root, BTRFS_I(inode));
+		if (err)
+			goto fail;
+		if (inode->i_nlink == 1) {
+			/*
+			 * If new hard link count is 1, it's a file created
+			 * with open(2) O_TMPFILE flag.
+			 */
+			err = btrfs_orphan_del(trans, BTRFS_I(inode));
+			if (err)
+				goto fail;
+		}
+		d_instantiate(dentry, inode);
+		btrfs_log_new_name(trans, old_dentry, NULL, 0, parent);
+	}
+
+fail:
+	fscrypt_free_filename(&fname);
+	if (trans)
+		btrfs_end_transaction(trans);
+	if (drop_inode) {
+		inode_dec_link_count(inode);
+		iput(inode);
+	}
+	btrfs_btree_balance_dirty(fs_info);
+	return err;
+}
+
+static int btrfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
+		       struct dentry *dentry, umode_t mode)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, S_IFDIR | mode);
+	inode->i_op = &btrfs_dir_inode_operations;
+	inode->i_fop = &btrfs_dir_file_operations;
+	return btrfs_create_common(dir, dentry, inode);
+}
+
+static noinline int uncompress_inline(struct btrfs_path *path,
+				      struct page *page,
+				      struct btrfs_file_extent_item *item)
+{
+	int ret;
+	struct extent_buffer *leaf = path->nodes[0];
+	char *tmp;
+	size_t max_size;
+	unsigned long inline_size;
+	unsigned long ptr;
+	int compress_type;
+
+	compress_type = btrfs_file_extent_compression(leaf, item);
+	max_size = btrfs_file_extent_ram_bytes(leaf, item);
+	inline_size = btrfs_file_extent_inline_item_len(leaf, path->slots[0]);
+	tmp = kmalloc(inline_size, GFP_NOFS);
+	if (!tmp)
+		return -ENOMEM;
+	ptr = btrfs_file_extent_inline_start(item);
+
+	read_extent_buffer(leaf, tmp, ptr, inline_size);
+
+	max_size = min_t(unsigned long, PAGE_SIZE, max_size);
+	ret = btrfs_decompress(compress_type, tmp, page, 0, inline_size, max_size);
+
+	/*
+	 * decompression code contains a memset to fill in any space between the end
+	 * of the uncompressed data and the end of max_size in case the decompressed
+	 * data ends up shorter than ram_bytes.  That doesn't cover the hole between
+	 * the end of an inline extent and the beginning of the next block, so we
+	 * cover that region here.
+	 */
+
+	if (max_size < PAGE_SIZE)
+		memzero_page(page, max_size, PAGE_SIZE - max_size);
+	kfree(tmp);
+	return ret;
+}
+
+static int read_inline_extent(struct btrfs_inode *inode, struct btrfs_path *path,
+			      struct page *page)
+{
+	struct btrfs_file_extent_item *fi;
+	void *kaddr;
+	size_t copy_size;
+
+	if (!page || PageUptodate(page))
+		return 0;
+
+	ASSERT(page_offset(page) == 0);
+
+	fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			    struct btrfs_file_extent_item);
+	if (btrfs_file_extent_compression(path->nodes[0], fi) != BTRFS_COMPRESS_NONE)
+		return uncompress_inline(path, page, fi);
+
+	copy_size = min_t(u64, PAGE_SIZE,
+			  btrfs_file_extent_ram_bytes(path->nodes[0], fi));
+	kaddr = kmap_local_page(page);
+	read_extent_buffer(path->nodes[0], kaddr,
+			   btrfs_file_extent_inline_start(fi), copy_size);
+	kunmap_local(kaddr);
+	if (copy_size < PAGE_SIZE)
+		memzero_page(page, copy_size, PAGE_SIZE - copy_size);
+	return 0;
+}
+
+/*
+ * Lookup the first extent overlapping a range in a file.
+ *
+ * @inode:	file to search in
+ * @page:	page to read extent data into if the extent is inline
+ * @pg_offset:	offset into @page to copy to
+ * @start:	file offset
+ * @len:	length of range starting at @start
+ *
+ * Return the first &struct extent_map which overlaps the given range, reading
+ * it from the B-tree and caching it if necessary. Note that there may be more
+ * extents which overlap the given range after the returned extent_map.
+ *
+ * If @page is not NULL and the extent is inline, this also reads the extent
+ * data directly into the page and marks the extent up to date in the io_tree.
+ *
+ * Return: ERR_PTR on error, non-NULL extent_map on success.
+ */
+struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
+				    struct page *page, size_t pg_offset,
+				    u64 start, u64 len)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	int ret = 0;
+	u64 extent_start = 0;
+	u64 extent_end = 0;
+	u64 objectid = btrfs_ino(inode);
+	int extent_type = -1;
+	struct btrfs_path *path = NULL;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_file_extent_item *item;
+	struct extent_buffer *leaf;
+	struct btrfs_key found_key;
+	struct extent_map *em = NULL;
+	struct extent_map_tree *em_tree = &inode->extent_tree;
+
+	read_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, start, len);
+	read_unlock(&em_tree->lock);
+
+	if (em) {
+		if (em->start > start || em->start + em->len <= start)
+			free_extent_map(em);
+		else if (em->block_start == EXTENT_MAP_INLINE && page)
+			free_extent_map(em);
+		else
+			goto out;
+	}
+	em = alloc_extent_map();
+	if (!em) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	em->start = EXTENT_MAP_HOLE;
+	em->orig_start = EXTENT_MAP_HOLE;
+	em->len = (u64)-1;
+	em->block_len = (u64)-1;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	/* Chances are we'll be called again, so go ahead and do readahead */
+	path->reada = READA_FORWARD;
+
+	/*
+	 * The same explanation in load_free_space_cache applies here as well,
+	 * we only read when we're loading the free space cache, and at that
+	 * point the commit_root has everything we need.
+	 */
+	if (btrfs_is_free_space_inode(inode)) {
+		path->search_commit_root = 1;
+		path->skip_locking = 1;
+	}
+
+	ret = btrfs_lookup_file_extent(NULL, root, path, objectid, start, 0);
+	if (ret < 0) {
+		goto out;
+	} else if (ret > 0) {
+		if (path->slots[0] == 0)
+			goto not_found;
+		path->slots[0]--;
+		ret = 0;
+	}
+
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0],
+			      struct btrfs_file_extent_item);
+	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+	if (found_key.objectid != objectid ||
+	    found_key.type != BTRFS_EXTENT_DATA_KEY) {
+		/*
+		 * If we backup past the first extent we want to move forward
+		 * and see if there is an extent in front of us, otherwise we'll
+		 * say there is a hole for our whole search range which can
+		 * cause problems.
+		 */
+		extent_end = start;
+		goto next;
+	}
+
+	extent_type = btrfs_file_extent_type(leaf, item);
+	extent_start = found_key.offset;
+	extent_end = btrfs_file_extent_end(path);
+	if (extent_type == BTRFS_FILE_EXTENT_REG ||
+	    extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		/* Only regular file could have regular/prealloc extent */
+		if (!S_ISREG(inode->vfs_inode.i_mode)) {
+			ret = -EUCLEAN;
+			btrfs_crit(fs_info,
+		"regular/prealloc extent found for non-regular inode %llu",
+				   btrfs_ino(inode));
+			goto out;
+		}
+		trace_btrfs_get_extent_show_fi_regular(inode, leaf, item,
+						       extent_start);
+	} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+		trace_btrfs_get_extent_show_fi_inline(inode, leaf, item,
+						      path->slots[0],
+						      extent_start);
+	}
+next:
+	if (start >= extent_end) {
+		path->slots[0]++;
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			else if (ret > 0)
+				goto not_found;
+
+			leaf = path->nodes[0];
+		}
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		if (found_key.objectid != objectid ||
+		    found_key.type != BTRFS_EXTENT_DATA_KEY)
+			goto not_found;
+		if (start + len <= found_key.offset)
+			goto not_found;
+		if (start > found_key.offset)
+			goto next;
+
+		/* New extent overlaps with existing one */
+		em->start = start;
+		em->orig_start = start;
+		em->len = found_key.offset - start;
+		em->block_start = EXTENT_MAP_HOLE;
+		goto insert;
+	}
+
+	btrfs_extent_item_to_extent_map(inode, path, item, em);
+
+	if (extent_type == BTRFS_FILE_EXTENT_REG ||
+	    extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		goto insert;
+	} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+		/*
+		 * Inline extent can only exist at file offset 0. This is
+		 * ensured by tree-checker and inline extent creation path.
+		 * Thus all members representing file offsets should be zero.
+		 */
+		ASSERT(pg_offset == 0);
+		ASSERT(extent_start == 0);
+		ASSERT(em->start == 0);
+
+		/*
+		 * btrfs_extent_item_to_extent_map() should have properly
+		 * initialized em members already.
+		 *
+		 * Other members are not utilized for inline extents.
+		 */
+		ASSERT(em->block_start == EXTENT_MAP_INLINE);
+		ASSERT(em->len == fs_info->sectorsize);
+
+		ret = read_inline_extent(inode, path, page);
+		if (ret < 0)
+			goto out;
+		goto insert;
+	}
+not_found:
+	em->start = start;
+	em->orig_start = start;
+	em->len = len;
+	em->block_start = EXTENT_MAP_HOLE;
+insert:
+	ret = 0;
+	btrfs_release_path(path);
+	if (em->start > start || extent_map_end(em) <= start) {
+		btrfs_err(fs_info,
+			  "bad extent! em: [%llu %llu] passed [%llu %llu]",
+			  em->start, em->len, start, len);
+		ret = -EIO;
+		goto out;
+	}
+
+	write_lock(&em_tree->lock);
+	ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, start, len);
+	write_unlock(&em_tree->lock);
+out:
+	btrfs_free_path(path);
+
+	trace_btrfs_get_extent(root, inode, em);
+
+	if (ret) {
+		free_extent_map(em);
+		return ERR_PTR(ret);
+	}
+	return em;
+}
+
+static struct extent_map *btrfs_create_dio_extent(struct btrfs_inode *inode,
+						  struct btrfs_dio_data *dio_data,
+						  const u64 start,
+						  const u64 len,
+						  const u64 orig_start,
+						  const u64 block_start,
+						  const u64 block_len,
+						  const u64 orig_block_len,
+						  const u64 ram_bytes,
+						  const int type)
+{
+	struct extent_map *em = NULL;
+	struct btrfs_ordered_extent *ordered;
+
+	if (type != BTRFS_ORDERED_NOCOW) {
+		em = create_io_em(inode, start, len, orig_start, block_start,
+				  block_len, orig_block_len, ram_bytes,
+				  BTRFS_COMPRESS_NONE, /* compress_type */
+				  type);
+		if (IS_ERR(em))
+			goto out;
+	}
+	ordered = btrfs_alloc_ordered_extent(inode, start, len, len,
+					     block_start, block_len, 0,
+					     (1 << type) |
+					     (1 << BTRFS_ORDERED_DIRECT),
+					     BTRFS_COMPRESS_NONE);
+	if (IS_ERR(ordered)) {
+		if (em) {
+			free_extent_map(em);
+			btrfs_drop_extent_map_range(inode, start,
+						    start + len - 1, false);
+		}
+		em = ERR_CAST(ordered);
+	} else {
+		ASSERT(!dio_data->ordered);
+		dio_data->ordered = ordered;
+	}
+ out:
+
+	return em;
+}
+
+static struct extent_map *btrfs_new_extent_direct(struct btrfs_inode *inode,
+						  struct btrfs_dio_data *dio_data,
+						  u64 start, u64 len)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_map *em;
+	struct btrfs_key ins;
+	u64 alloc_hint;
+	int ret;
+
+	alloc_hint = get_extent_allocation_hint(inode, start, len);
+again:
+	ret = btrfs_reserve_extent(root, len, len, fs_info->sectorsize,
+				   0, alloc_hint, &ins, 1, 1);
+	if (ret == -EAGAIN) {
+		ASSERT(btrfs_is_zoned(fs_info));
+		wait_on_bit_io(&inode->root->fs_info->flags, BTRFS_FS_NEED_ZONE_FINISH,
+			       TASK_UNINTERRUPTIBLE);
+		goto again;
+	}
+	if (ret)
+		return ERR_PTR(ret);
+
+	em = btrfs_create_dio_extent(inode, dio_data, start, ins.offset, start,
+				     ins.objectid, ins.offset, ins.offset,
+				     ins.offset, BTRFS_ORDERED_REGULAR);
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+	if (IS_ERR(em))
+		btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset,
+					   1);
+
+	return em;
+}
+
+static bool btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr)
+{
+	struct btrfs_block_group *block_group;
+	bool readonly = false;
+
+	block_group = btrfs_lookup_block_group(fs_info, bytenr);
+	if (!block_group || block_group->ro)
+		readonly = true;
+	if (block_group)
+		btrfs_put_block_group(block_group);
+	return readonly;
+}
+
+/*
+ * Check if we can do nocow write into the range [@offset, @offset + @len)
+ *
+ * @offset:	File offset
+ * @len:	The length to write, will be updated to the nocow writeable
+ *		range
+ * @orig_start:	(optional) Return the original file offset of the file extent
+ * @orig_len:	(optional) Return the original on-disk length of the file extent
+ * @ram_bytes:	(optional) Return the ram_bytes of the file extent
+ * @strict:	if true, omit optimizations that might force us into unnecessary
+ *		cow. e.g., don't trust generation number.
+ *
+ * Return:
+ * >0	and update @len if we can do nocow write
+ *  0	if we can't do nocow write
+ * <0	if error happened
+ *
+ * NOTE: This only checks the file extents, caller is responsible to wait for
+ *	 any ordered extents.
+ */
+noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
+			      u64 *orig_start, u64 *orig_block_len,
+			      u64 *ram_bytes, bool nowait, bool strict)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct can_nocow_file_extent_args nocow_args = { 0 };
+	struct btrfs_path *path;
+	int ret;
+	struct extent_buffer *leaf;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_key key;
+	int found_type;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	path->nowait = nowait;
+
+	ret = btrfs_lookup_file_extent(NULL, root, path,
+			btrfs_ino(BTRFS_I(inode)), offset, 0);
+	if (ret < 0)
+		goto out;
+
+	if (ret == 1) {
+		if (path->slots[0] == 0) {
+			/* can't find the item, must cow */
+			ret = 0;
+			goto out;
+		}
+		path->slots[0]--;
+	}
+	ret = 0;
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+	if (key.objectid != btrfs_ino(BTRFS_I(inode)) ||
+	    key.type != BTRFS_EXTENT_DATA_KEY) {
+		/* not our file or wrong item type, must cow */
+		goto out;
+	}
+
+	if (key.offset > offset) {
+		/* Wrong offset, must cow */
+		goto out;
+	}
+
+	if (btrfs_file_extent_end(path) <= offset)
+		goto out;
+
+	fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
+	found_type = btrfs_file_extent_type(leaf, fi);
+	if (ram_bytes)
+		*ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
+
+	nocow_args.start = offset;
+	nocow_args.end = offset + *len - 1;
+	nocow_args.strict = strict;
+	nocow_args.free_path = true;
+
+	ret = can_nocow_file_extent(path, &key, BTRFS_I(inode), &nocow_args);
+	/* can_nocow_file_extent() has freed the path. */
+	path = NULL;
+
+	if (ret != 1) {
+		/* Treat errors as not being able to NOCOW. */
+		ret = 0;
+		goto out;
+	}
+
+	ret = 0;
+	if (btrfs_extent_readonly(fs_info, nocow_args.disk_bytenr))
+		goto out;
+
+	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
+	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		u64 range_end;
+
+		range_end = round_up(offset + nocow_args.num_bytes,
+				     root->fs_info->sectorsize) - 1;
+		ret = test_range_bit(io_tree, offset, range_end,
+				     EXTENT_DELALLOC, 0, NULL);
+		if (ret) {
+			ret = -EAGAIN;
+			goto out;
+		}
+	}
+
+	if (orig_start)
+		*orig_start = key.offset - nocow_args.extent_offset;
+	if (orig_block_len)
+		*orig_block_len = nocow_args.disk_num_bytes;
+
+	*len = nocow_args.num_bytes;
+	ret = 1;
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
+			      struct extent_state **cached_state,
+			      unsigned int iomap_flags)
+{
+	const bool writing = (iomap_flags & IOMAP_WRITE);
+	const bool nowait = (iomap_flags & IOMAP_NOWAIT);
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct btrfs_ordered_extent *ordered;
+	int ret = 0;
+
+	while (1) {
+		if (nowait) {
+			if (!try_lock_extent(io_tree, lockstart, lockend,
+					     cached_state))
+				return -EAGAIN;
+		} else {
+			lock_extent(io_tree, lockstart, lockend, cached_state);
+		}
+		/*
+		 * We're concerned with the entire range that we're going to be
+		 * doing DIO to, so we need to make sure there's no ordered
+		 * extents in this range.
+		 */
+		ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), lockstart,
+						     lockend - lockstart + 1);
+
+		/*
+		 * We need to make sure there are no buffered pages in this
+		 * range either, we could have raced between the invalidate in
+		 * generic_file_direct_write and locking the extent.  The
+		 * invalidate needs to happen so that reads after a write do not
+		 * get stale data.
+		 */
+		if (!ordered &&
+		    (!writing || !filemap_range_has_page(inode->i_mapping,
+							 lockstart, lockend)))
+			break;
+
+		unlock_extent(io_tree, lockstart, lockend, cached_state);
+
+		if (ordered) {
+			if (nowait) {
+				btrfs_put_ordered_extent(ordered);
+				ret = -EAGAIN;
+				break;
+			}
+			/*
+			 * If we are doing a DIO read and the ordered extent we
+			 * found is for a buffered write, we can not wait for it
+			 * to complete and retry, because if we do so we can
+			 * deadlock with concurrent buffered writes on page
+			 * locks. This happens only if our DIO read covers more
+			 * than one extent map, if at this point has already
+			 * created an ordered extent for a previous extent map
+			 * and locked its range in the inode's io tree, and a
+			 * concurrent write against that previous extent map's
+			 * range and this range started (we unlock the ranges
+			 * in the io tree only when the bios complete and
+			 * buffered writes always lock pages before attempting
+			 * to lock range in the io tree).
+			 */
+			if (writing ||
+			    test_bit(BTRFS_ORDERED_DIRECT, &ordered->flags))
+				btrfs_start_ordered_extent(ordered);
+			else
+				ret = nowait ? -EAGAIN : -ENOTBLK;
+			btrfs_put_ordered_extent(ordered);
+		} else {
+			/*
+			 * We could trigger writeback for this range (and wait
+			 * for it to complete) and then invalidate the pages for
+			 * this range (through invalidate_inode_pages2_range()),
+			 * but that can lead us to a deadlock with a concurrent
+			 * call to readahead (a buffered read or a defrag call
+			 * triggered a readahead) on a page lock due to an
+			 * ordered dio extent we created before but did not have
+			 * yet a corresponding bio submitted (whence it can not
+			 * complete), which makes readahead wait for that
+			 * ordered extent to complete while holding a lock on
+			 * that page.
+			 */
+			ret = nowait ? -EAGAIN : -ENOTBLK;
+		}
+
+		if (ret)
+			break;
+
+		cond_resched();
+	}
+
+	return ret;
+}
+
+/* The callers of this must take lock_extent() */
+static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
+				       u64 len, u64 orig_start, u64 block_start,
+				       u64 block_len, u64 orig_block_len,
+				       u64 ram_bytes, int compress_type,
+				       int type)
+{
+	struct extent_map *em;
+	int ret;
+
+	ASSERT(type == BTRFS_ORDERED_PREALLOC ||
+	       type == BTRFS_ORDERED_COMPRESSED ||
+	       type == BTRFS_ORDERED_NOCOW ||
+	       type == BTRFS_ORDERED_REGULAR);
+
+	em = alloc_extent_map();
+	if (!em)
+		return ERR_PTR(-ENOMEM);
+
+	em->start = start;
+	em->orig_start = orig_start;
+	em->len = len;
+	em->block_len = block_len;
+	em->block_start = block_start;
+	em->orig_block_len = orig_block_len;
+	em->ram_bytes = ram_bytes;
+	em->generation = -1;
+	set_bit(EXTENT_FLAG_PINNED, &em->flags);
+	if (type == BTRFS_ORDERED_PREALLOC) {
+		set_bit(EXTENT_FLAG_FILLING, &em->flags);
+	} else if (type == BTRFS_ORDERED_COMPRESSED) {
+		set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+		em->compress_type = compress_type;
+	}
+
+	ret = btrfs_replace_extent_map_range(inode, em, true);
+	if (ret) {
+		free_extent_map(em);
+		return ERR_PTR(ret);
+	}
+
+	/* em got 2 refs now, callers needs to do free_extent_map once. */
+	return em;
+}
+
+
+static int btrfs_get_blocks_direct_write(struct extent_map **map,
+					 struct inode *inode,
+					 struct btrfs_dio_data *dio_data,
+					 u64 start, u64 *lenp,
+					 unsigned int iomap_flags)
+{
+	const bool nowait = (iomap_flags & IOMAP_NOWAIT);
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct extent_map *em = *map;
+	int type;
+	u64 block_start, orig_start, orig_block_len, ram_bytes;
+	struct btrfs_block_group *bg;
+	bool can_nocow = false;
+	bool space_reserved = false;
+	u64 len = *lenp;
+	u64 prev_len;
+	int ret = 0;
+
+	/*
+	 * We don't allocate a new extent in the following cases
+	 *
+	 * 1) The inode is marked as NODATACOW. In this case we'll just use the
+	 * existing extent.
+	 * 2) The extent is marked as PREALLOC. We're good to go here and can
+	 * just use the extent.
+	 *
+	 */
+	if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) ||
+	    ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
+	     em->block_start != EXTENT_MAP_HOLE)) {
+		if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+			type = BTRFS_ORDERED_PREALLOC;
+		else
+			type = BTRFS_ORDERED_NOCOW;
+		len = min(len, em->len - (start - em->start));
+		block_start = em->block_start + (start - em->start);
+
+		if (can_nocow_extent(inode, start, &len, &orig_start,
+				     &orig_block_len, &ram_bytes, false, false) == 1) {
+			bg = btrfs_inc_nocow_writers(fs_info, block_start);
+			if (bg)
+				can_nocow = true;
+		}
+	}
+
+	prev_len = len;
+	if (can_nocow) {
+		struct extent_map *em2;
+
+		/* We can NOCOW, so only need to reserve metadata space. */
+		ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), len, len,
+						      nowait);
+		if (ret < 0) {
+			/* Our caller expects us to free the input extent map. */
+			free_extent_map(em);
+			*map = NULL;
+			btrfs_dec_nocow_writers(bg);
+			if (nowait && (ret == -ENOSPC || ret == -EDQUOT))
+				ret = -EAGAIN;
+			goto out;
+		}
+		space_reserved = true;
+
+		em2 = btrfs_create_dio_extent(BTRFS_I(inode), dio_data, start, len,
+					      orig_start, block_start,
+					      len, orig_block_len,
+					      ram_bytes, type);
+		btrfs_dec_nocow_writers(bg);
+		if (type == BTRFS_ORDERED_PREALLOC) {
+			free_extent_map(em);
+			*map = em2;
+			em = em2;
+		}
+
+		if (IS_ERR(em2)) {
+			ret = PTR_ERR(em2);
+			goto out;
+		}
+
+		dio_data->nocow_done = true;
+	} else {
+		/* Our caller expects us to free the input extent map. */
+		free_extent_map(em);
+		*map = NULL;
+
+		if (nowait) {
+			ret = -EAGAIN;
+			goto out;
+		}
+
+		/*
+		 * If we could not allocate data space before locking the file
+		 * range and we can't do a NOCOW write, then we have to fail.
+		 */
+		if (!dio_data->data_space_reserved) {
+			ret = -ENOSPC;
+			goto out;
+		}
+
+		/*
+		 * We have to COW and we have already reserved data space before,
+		 * so now we reserve only metadata.
+		 */
+		ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), len, len,
+						      false);
+		if (ret < 0)
+			goto out;
+		space_reserved = true;
+
+		em = btrfs_new_extent_direct(BTRFS_I(inode), dio_data, start, len);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			goto out;
+		}
+		*map = em;
+		len = min(len, em->len - (start - em->start));
+		if (len < prev_len)
+			btrfs_delalloc_release_metadata(BTRFS_I(inode),
+							prev_len - len, true);
+	}
+
+	/*
+	 * We have created our ordered extent, so we can now release our reservation
+	 * for an outstanding extent.
+	 */
+	btrfs_delalloc_release_extents(BTRFS_I(inode), prev_len);
+
+	/*
+	 * Need to update the i_size under the extent lock so buffered
+	 * readers will get the updated i_size when we unlock.
+	 */
+	if (start + len > i_size_read(inode))
+		i_size_write(inode, start + len);
+out:
+	if (ret && space_reserved) {
+		btrfs_delalloc_release_extents(BTRFS_I(inode), len);
+		btrfs_delalloc_release_metadata(BTRFS_I(inode), len, true);
+	}
+	*lenp = len;
+	return ret;
+}
+
+static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
+		loff_t length, unsigned int flags, struct iomap *iomap,
+		struct iomap *srcmap)
+{
+	struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct extent_map *em;
+	struct extent_state *cached_state = NULL;
+	struct btrfs_dio_data *dio_data = iter->private;
+	u64 lockstart, lockend;
+	const bool write = !!(flags & IOMAP_WRITE);
+	int ret = 0;
+	u64 len = length;
+	const u64 data_alloc_len = length;
+	bool unlock_extents = false;
+
+	/*
+	 * We could potentially fault if we have a buffer > PAGE_SIZE, and if
+	 * we're NOWAIT we may submit a bio for a partial range and return
+	 * EIOCBQUEUED, which would result in an errant short read.
+	 *
+	 * The best way to handle this would be to allow for partial completions
+	 * of iocb's, so we could submit the partial bio, return and fault in
+	 * the rest of the pages, and then submit the io for the rest of the
+	 * range.  However we don't have that currently, so simply return
+	 * -EAGAIN at this point so that the normal path is used.
+	 */
+	if (!write && (flags & IOMAP_NOWAIT) && length > PAGE_SIZE)
+		return -EAGAIN;
+
+	/*
+	 * Cap the size of reads to that usually seen in buffered I/O as we need
+	 * to allocate a contiguous array for the checksums.
+	 */
+	if (!write)
+		len = min_t(u64, len, fs_info->sectorsize * BTRFS_MAX_BIO_SECTORS);
+
+	lockstart = start;
+	lockend = start + len - 1;
+
+	/*
+	 * iomap_dio_rw() only does filemap_write_and_wait_range(), which isn't
+	 * enough if we've written compressed pages to this area, so we need to
+	 * flush the dirty pages again to make absolutely sure that any
+	 * outstanding dirty pages are on disk - the first flush only starts
+	 * compression on the data, while keeping the pages locked, so by the
+	 * time the second flush returns we know bios for the compressed pages
+	 * were submitted and finished, and the pages no longer under writeback.
+	 *
+	 * If we have a NOWAIT request and we have any pages in the range that
+	 * are locked, likely due to compression still in progress, we don't want
+	 * to block on page locks. We also don't want to block on pages marked as
+	 * dirty or under writeback (same as for the non-compression case).
+	 * iomap_dio_rw() did the same check, but after that and before we got
+	 * here, mmap'ed writes may have happened or buffered reads started
+	 * (readpage() and readahead(), which lock pages), as we haven't locked
+	 * the file range yet.
+	 */
+	if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+		     &BTRFS_I(inode)->runtime_flags)) {
+		if (flags & IOMAP_NOWAIT) {
+			if (filemap_range_needs_writeback(inode->i_mapping,
+							  lockstart, lockend))
+				return -EAGAIN;
+		} else {
+			ret = filemap_fdatawrite_range(inode->i_mapping, start,
+						       start + length - 1);
+			if (ret)
+				return ret;
+		}
+	}
+
+	memset(dio_data, 0, sizeof(*dio_data));
+
+	/*
+	 * We always try to allocate data space and must do it before locking
+	 * the file range, to avoid deadlocks with concurrent writes to the same
+	 * range if the range has several extents and the writes don't expand the
+	 * current i_size (the inode lock is taken in shared mode). If we fail to
+	 * allocate data space here we continue and later, after locking the
+	 * file range, we fail with ENOSPC only if we figure out we can not do a
+	 * NOCOW write.
+	 */
+	if (write && !(flags & IOMAP_NOWAIT)) {
+		ret = btrfs_check_data_free_space(BTRFS_I(inode),
+						  &dio_data->data_reserved,
+						  start, data_alloc_len, false);
+		if (!ret)
+			dio_data->data_space_reserved = true;
+		else if (ret && !(BTRFS_I(inode)->flags &
+				  (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
+			goto err;
+	}
+
+	/*
+	 * If this errors out it's because we couldn't invalidate pagecache for
+	 * this range and we need to fallback to buffered IO, or we are doing a
+	 * NOWAIT read/write and we need to block.
+	 */
+	ret = lock_extent_direct(inode, lockstart, lockend, &cached_state, flags);
+	if (ret < 0)
+		goto err;
+
+	em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto unlock_err;
+	}
+
+	/*
+	 * Ok for INLINE and COMPRESSED extents we need to fallback on buffered
+	 * io.  INLINE is special, and we could probably kludge it in here, but
+	 * it's still buffered so for safety lets just fall back to the generic
+	 * buffered path.
+	 *
+	 * For COMPRESSED we _have_ to read the entire extent in so we can
+	 * decompress it, so there will be buffering required no matter what we
+	 * do, so go ahead and fallback to buffered.
+	 *
+	 * We return -ENOTBLK because that's what makes DIO go ahead and go back
+	 * to buffered IO.  Don't blame me, this is the price we pay for using
+	 * the generic code.
+	 */
+	if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) ||
+	    em->block_start == EXTENT_MAP_INLINE) {
+		free_extent_map(em);
+		/*
+		 * If we are in a NOWAIT context, return -EAGAIN in order to
+		 * fallback to buffered IO. This is not only because we can
+		 * block with buffered IO (no support for NOWAIT semantics at
+		 * the moment) but also to avoid returning short reads to user
+		 * space - this happens if we were able to read some data from
+		 * previous non-compressed extents and then when we fallback to
+		 * buffered IO, at btrfs_file_read_iter() by calling
+		 * filemap_read(), we fail to fault in pages for the read buffer,
+		 * in which case filemap_read() returns a short read (the number
+		 * of bytes previously read is > 0, so it does not return -EFAULT).
+		 */
+		ret = (flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOTBLK;
+		goto unlock_err;
+	}
+
+	len = min(len, em->len - (start - em->start));
+
+	/*
+	 * If we have a NOWAIT request and the range contains multiple extents
+	 * (or a mix of extents and holes), then we return -EAGAIN to make the
+	 * caller fallback to a context where it can do a blocking (without
+	 * NOWAIT) request. This way we avoid doing partial IO and returning
+	 * success to the caller, which is not optimal for writes and for reads
+	 * it can result in unexpected behaviour for an application.
+	 *
+	 * When doing a read, because we use IOMAP_DIO_PARTIAL when calling
+	 * iomap_dio_rw(), we can end up returning less data then what the caller
+	 * asked for, resulting in an unexpected, and incorrect, short read.
+	 * That is, the caller asked to read N bytes and we return less than that,
+	 * which is wrong unless we are crossing EOF. This happens if we get a
+	 * page fault error when trying to fault in pages for the buffer that is
+	 * associated to the struct iov_iter passed to iomap_dio_rw(), and we
+	 * have previously submitted bios for other extents in the range, in
+	 * which case iomap_dio_rw() may return us EIOCBQUEUED if not all of
+	 * those bios have completed by the time we get the page fault error,
+	 * which we return back to our caller - we should only return EIOCBQUEUED
+	 * after we have submitted bios for all the extents in the range.
+	 */
+	if ((flags & IOMAP_NOWAIT) && len < length) {
+		free_extent_map(em);
+		ret = -EAGAIN;
+		goto unlock_err;
+	}
+
+	if (write) {
+		ret = btrfs_get_blocks_direct_write(&em, inode, dio_data,
+						    start, &len, flags);
+		if (ret < 0)
+			goto unlock_err;
+		unlock_extents = true;
+		/* Recalc len in case the new em is smaller than requested */
+		len = min(len, em->len - (start - em->start));
+		if (dio_data->data_space_reserved) {
+			u64 release_offset;
+			u64 release_len = 0;
+
+			if (dio_data->nocow_done) {
+				release_offset = start;
+				release_len = data_alloc_len;
+			} else if (len < data_alloc_len) {
+				release_offset = start + len;
+				release_len = data_alloc_len - len;
+			}
+
+			if (release_len > 0)
+				btrfs_free_reserved_data_space(BTRFS_I(inode),
+							       dio_data->data_reserved,
+							       release_offset,
+							       release_len);
+		}
+	} else {
+		/*
+		 * We need to unlock only the end area that we aren't using.
+		 * The rest is going to be unlocked by the endio routine.
+		 */
+		lockstart = start + len;
+		if (lockstart < lockend)
+			unlock_extents = true;
+	}
+
+	if (unlock_extents)
+		unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend,
+			      &cached_state);
+	else
+		free_extent_state(cached_state);
+
+	/*
+	 * Translate extent map information to iomap.
+	 * We trim the extents (and move the addr) even though iomap code does
+	 * that, since we have locked only the parts we are performing I/O in.
+	 */
+	if ((em->block_start == EXTENT_MAP_HOLE) ||
+	    (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) && !write)) {
+		iomap->addr = IOMAP_NULL_ADDR;
+		iomap->type = IOMAP_HOLE;
+	} else {
+		iomap->addr = em->block_start + (start - em->start);
+		iomap->type = IOMAP_MAPPED;
+	}
+	iomap->offset = start;
+	iomap->bdev = fs_info->fs_devices->latest_dev->bdev;
+	iomap->length = len;
+	free_extent_map(em);
+
+	return 0;
+
+unlock_err:
+	unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend,
+		      &cached_state);
+err:
+	if (dio_data->data_space_reserved) {
+		btrfs_free_reserved_data_space(BTRFS_I(inode),
+					       dio_data->data_reserved,
+					       start, data_alloc_len);
+		extent_changeset_free(dio_data->data_reserved);
+	}
+
+	return ret;
+}
+
+static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
+		ssize_t written, unsigned int flags, struct iomap *iomap)
+{
+	struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
+	struct btrfs_dio_data *dio_data = iter->private;
+	size_t submitted = dio_data->submitted;
+	const bool write = !!(flags & IOMAP_WRITE);
+	int ret = 0;
+
+	if (!write && (iomap->type == IOMAP_HOLE)) {
+		/* If reading from a hole, unlock and return */
+		unlock_extent(&BTRFS_I(inode)->io_tree, pos, pos + length - 1,
+			      NULL);
+		return 0;
+	}
+
+	if (submitted < length) {
+		pos += submitted;
+		length -= submitted;
+		if (write)
+			btrfs_finish_ordered_extent(dio_data->ordered, NULL,
+						    pos, length, false);
+		else
+			unlock_extent(&BTRFS_I(inode)->io_tree, pos,
+				      pos + length - 1, NULL);
+		ret = -ENOTBLK;
+	}
+	if (write) {
+		btrfs_put_ordered_extent(dio_data->ordered);
+		dio_data->ordered = NULL;
+	}
+
+	if (write)
+		extent_changeset_free(dio_data->data_reserved);
+	return ret;
+}
+
+static void btrfs_dio_end_io(struct btrfs_bio *bbio)
+{
+	struct btrfs_dio_private *dip =
+		container_of(bbio, struct btrfs_dio_private, bbio);
+	struct btrfs_inode *inode = bbio->inode;
+	struct bio *bio = &bbio->bio;
+
+	if (bio->bi_status) {
+		btrfs_warn(inode->root->fs_info,
+		"direct IO failed ino %llu op 0x%0x offset %#llx len %u err no %d",
+			   btrfs_ino(inode), bio->bi_opf,
+			   dip->file_offset, dip->bytes, bio->bi_status);
+	}
+
+	if (btrfs_op(bio) == BTRFS_MAP_WRITE) {
+		btrfs_finish_ordered_extent(bbio->ordered, NULL,
+					    dip->file_offset, dip->bytes,
+					    !bio->bi_status);
+	} else {
+		unlock_extent(&inode->io_tree, dip->file_offset,
+			      dip->file_offset + dip->bytes - 1, NULL);
+	}
+
+	bbio->bio.bi_private = bbio->private;
+	iomap_dio_bio_end_io(bio);
+}
+
+static void btrfs_dio_submit_io(const struct iomap_iter *iter, struct bio *bio,
+				loff_t file_offset)
+{
+	struct btrfs_bio *bbio = btrfs_bio(bio);
+	struct btrfs_dio_private *dip =
+		container_of(bbio, struct btrfs_dio_private, bbio);
+	struct btrfs_dio_data *dio_data = iter->private;
+
+	btrfs_bio_init(bbio, BTRFS_I(iter->inode)->root->fs_info,
+		       btrfs_dio_end_io, bio->bi_private);
+	bbio->inode = BTRFS_I(iter->inode);
+	bbio->file_offset = file_offset;
+
+	dip->file_offset = file_offset;
+	dip->bytes = bio->bi_iter.bi_size;
+
+	dio_data->submitted += bio->bi_iter.bi_size;
+
+	/*
+	 * Check if we are doing a partial write.  If we are, we need to split
+	 * the ordered extent to match the submitted bio.  Hang on to the
+	 * remaining unfinishable ordered_extent in dio_data so that it can be
+	 * cancelled in iomap_end to avoid a deadlock wherein faulting the
+	 * remaining pages is blocked on the outstanding ordered extent.
+	 */
+	if (iter->flags & IOMAP_WRITE) {
+		int ret;
+
+		ret = btrfs_extract_ordered_extent(bbio, dio_data->ordered);
+		if (ret) {
+			btrfs_finish_ordered_extent(dio_data->ordered, NULL,
+						    file_offset, dip->bytes,
+						    !ret);
+			bio->bi_status = errno_to_blk_status(ret);
+			iomap_dio_bio_end_io(bio);
+			return;
+		}
+	}
+
+	btrfs_submit_bio(bbio, 0);
+}
+
+static const struct iomap_ops btrfs_dio_iomap_ops = {
+	.iomap_begin            = btrfs_dio_iomap_begin,
+	.iomap_end              = btrfs_dio_iomap_end,
+};
+
+static const struct iomap_dio_ops btrfs_dio_ops = {
+	.submit_io		= btrfs_dio_submit_io,
+	.bio_set		= &btrfs_dio_bioset,
+};
+
+ssize_t btrfs_dio_read(struct kiocb *iocb, struct iov_iter *iter, size_t done_before)
+{
+	struct btrfs_dio_data data = { 0 };
+
+	return iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
+			    IOMAP_DIO_PARTIAL, &data, done_before);
+}
+
+struct iomap_dio *btrfs_dio_write(struct kiocb *iocb, struct iov_iter *iter,
+				  size_t done_before)
+{
+	struct btrfs_dio_data data = { 0 };
+
+	return __iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
+			    IOMAP_DIO_PARTIAL, &data, done_before);
+}
+
+static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+			u64 start, u64 len)
+{
+	int	ret;
+
+	ret = fiemap_prep(inode, fieinfo, start, &len, 0);
+	if (ret)
+		return ret;
+
+	/*
+	 * fiemap_prep() called filemap_write_and_wait() for the whole possible
+	 * file range (0 to LLONG_MAX), but that is not enough if we have
+	 * compression enabled. The first filemap_fdatawrite_range() only kicks
+	 * in the compression of data (in an async thread) and will return
+	 * before the compression is done and writeback is started. A second
+	 * filemap_fdatawrite_range() is needed to wait for the compression to
+	 * complete and writeback to start. We also need to wait for ordered
+	 * extents to complete, because our fiemap implementation uses mainly
+	 * file extent items to list the extents, searching for extent maps
+	 * only for file ranges with holes or prealloc extents to figure out
+	 * if we have delalloc in those ranges.
+	 */
+	if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC) {
+		ret = btrfs_wait_ordered_range(inode, 0, LLONG_MAX);
+		if (ret)
+			return ret;
+	}
+
+	return extent_fiemap(BTRFS_I(inode), fieinfo, start, len);
+}
+
+static int btrfs_writepages(struct address_space *mapping,
+			    struct writeback_control *wbc)
+{
+	return extent_writepages(mapping, wbc);
+}
+
+static void btrfs_readahead(struct readahead_control *rac)
+{
+	extent_readahead(rac);
+}
+
+/*
+ * For release_folio() and invalidate_folio() we have a race window where
+ * folio_end_writeback() is called but the subpage spinlock is not yet released.
+ * If we continue to release/invalidate the page, we could cause use-after-free
+ * for subpage spinlock.  So this function is to spin and wait for subpage
+ * spinlock.
+ */
+static void wait_subpage_spinlock(struct page *page)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
+	struct btrfs_subpage *subpage;
+
+	if (!btrfs_is_subpage(fs_info, page))
+		return;
+
+	ASSERT(PagePrivate(page) && page->private);
+	subpage = (struct btrfs_subpage *)page->private;
+
+	/*
+	 * This may look insane as we just acquire the spinlock and release it,
+	 * without doing anything.  But we just want to make sure no one is
+	 * still holding the subpage spinlock.
+	 * And since the page is not dirty nor writeback, and we have page
+	 * locked, the only possible way to hold a spinlock is from the endio
+	 * function to clear page writeback.
+	 *
+	 * Here we just acquire the spinlock so that all existing callers
+	 * should exit and we're safe to release/invalidate the page.
+	 */
+	spin_lock_irq(&subpage->lock);
+	spin_unlock_irq(&subpage->lock);
+}
+
+static bool __btrfs_release_folio(struct folio *folio, gfp_t gfp_flags)
+{
+	int ret = try_release_extent_mapping(&folio->page, gfp_flags);
+
+	if (ret == 1) {
+		wait_subpage_spinlock(&folio->page);
+		clear_page_extent_mapped(&folio->page);
+	}
+	return ret;
+}
+
+static bool btrfs_release_folio(struct folio *folio, gfp_t gfp_flags)
+{
+	if (folio_test_writeback(folio) || folio_test_dirty(folio))
+		return false;
+	return __btrfs_release_folio(folio, gfp_flags);
+}
+
+#ifdef CONFIG_MIGRATION
+static int btrfs_migrate_folio(struct address_space *mapping,
+			     struct folio *dst, struct folio *src,
+			     enum migrate_mode mode)
+{
+	int ret = filemap_migrate_folio(mapping, dst, src, mode);
+
+	if (ret != MIGRATEPAGE_SUCCESS)
+		return ret;
+
+	if (folio_test_ordered(src)) {
+		folio_clear_ordered(src);
+		folio_set_ordered(dst);
+	}
+
+	return MIGRATEPAGE_SUCCESS;
+}
+#else
+#define btrfs_migrate_folio NULL
+#endif
+
+static void btrfs_invalidate_folio(struct folio *folio, size_t offset,
+				 size_t length)
+{
+	struct btrfs_inode *inode = BTRFS_I(folio->mapping->host);
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct extent_io_tree *tree = &inode->io_tree;
+	struct extent_state *cached_state = NULL;
+	u64 page_start = folio_pos(folio);
+	u64 page_end = page_start + folio_size(folio) - 1;
+	u64 cur;
+	int inode_evicting = inode->vfs_inode.i_state & I_FREEING;
+
+	/*
+	 * We have folio locked so no new ordered extent can be created on this
+	 * page, nor bio can be submitted for this folio.
+	 *
+	 * But already submitted bio can still be finished on this folio.
+	 * Furthermore, endio function won't skip folio which has Ordered
+	 * (Private2) already cleared, so it's possible for endio and
+	 * invalidate_folio to do the same ordered extent accounting twice
+	 * on one folio.
+	 *
+	 * So here we wait for any submitted bios to finish, so that we won't
+	 * do double ordered extent accounting on the same folio.
+	 */
+	folio_wait_writeback(folio);
+	wait_subpage_spinlock(&folio->page);
+
+	/*
+	 * For subpage case, we have call sites like
+	 * btrfs_punch_hole_lock_range() which passes range not aligned to
+	 * sectorsize.
+	 * If the range doesn't cover the full folio, we don't need to and
+	 * shouldn't clear page extent mapped, as folio->private can still
+	 * record subpage dirty bits for other part of the range.
+	 *
+	 * For cases that invalidate the full folio even the range doesn't
+	 * cover the full folio, like invalidating the last folio, we're
+	 * still safe to wait for ordered extent to finish.
+	 */
+	if (!(offset == 0 && length == folio_size(folio))) {
+		btrfs_release_folio(folio, GFP_NOFS);
+		return;
+	}
+
+	if (!inode_evicting)
+		lock_extent(tree, page_start, page_end, &cached_state);
+
+	cur = page_start;
+	while (cur < page_end) {
+		struct btrfs_ordered_extent *ordered;
+		u64 range_end;
+		u32 range_len;
+		u32 extra_flags = 0;
+
+		ordered = btrfs_lookup_first_ordered_range(inode, cur,
+							   page_end + 1 - cur);
+		if (!ordered) {
+			range_end = page_end;
+			/*
+			 * No ordered extent covering this range, we are safe
+			 * to delete all extent states in the range.
+			 */
+			extra_flags = EXTENT_CLEAR_ALL_BITS;
+			goto next;
+		}
+		if (ordered->file_offset > cur) {
+			/*
+			 * There is a range between [cur, oe->file_offset) not
+			 * covered by any ordered extent.
+			 * We are safe to delete all extent states, and handle
+			 * the ordered extent in the next iteration.
+			 */
+			range_end = ordered->file_offset - 1;
+			extra_flags = EXTENT_CLEAR_ALL_BITS;
+			goto next;
+		}
+
+		range_end = min(ordered->file_offset + ordered->num_bytes - 1,
+				page_end);
+		ASSERT(range_end + 1 - cur < U32_MAX);
+		range_len = range_end + 1 - cur;
+		if (!btrfs_page_test_ordered(fs_info, &folio->page, cur, range_len)) {
+			/*
+			 * If Ordered (Private2) is cleared, it means endio has
+			 * already been executed for the range.
+			 * We can't delete the extent states as
+			 * btrfs_finish_ordered_io() may still use some of them.
+			 */
+			goto next;
+		}
+		btrfs_page_clear_ordered(fs_info, &folio->page, cur, range_len);
+
+		/*
+		 * IO on this page will never be started, so we need to account
+		 * for any ordered extents now. Don't clear EXTENT_DELALLOC_NEW
+		 * here, must leave that up for the ordered extent completion.
+		 *
+		 * This will also unlock the range for incoming
+		 * btrfs_finish_ordered_io().
+		 */
+		if (!inode_evicting)
+			clear_extent_bit(tree, cur, range_end,
+					 EXTENT_DELALLOC |
+					 EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
+					 EXTENT_DEFRAG, &cached_state);
+
+		spin_lock_irq(&inode->ordered_tree.lock);
+		set_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags);
+		ordered->truncated_len = min(ordered->truncated_len,
+					     cur - ordered->file_offset);
+		spin_unlock_irq(&inode->ordered_tree.lock);
+
+		/*
+		 * If the ordered extent has finished, we're safe to delete all
+		 * the extent states of the range, otherwise
+		 * btrfs_finish_ordered_io() will get executed by endio for
+		 * other pages, so we can't delete extent states.
+		 */
+		if (btrfs_dec_test_ordered_pending(inode, &ordered,
+						   cur, range_end + 1 - cur)) {
+			btrfs_finish_ordered_io(ordered);
+			/*
+			 * The ordered extent has finished, now we're again
+			 * safe to delete all extent states of the range.
+			 */
+			extra_flags = EXTENT_CLEAR_ALL_BITS;
+		}
+next:
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+		/*
+		 * Qgroup reserved space handler
+		 * Sector(s) here will be either:
+		 *
+		 * 1) Already written to disk or bio already finished
+		 *    Then its QGROUP_RESERVED bit in io_tree is already cleared.
+		 *    Qgroup will be handled by its qgroup_record then.
+		 *    btrfs_qgroup_free_data() call will do nothing here.
+		 *
+		 * 2) Not written to disk yet
+		 *    Then btrfs_qgroup_free_data() call will clear the
+		 *    QGROUP_RESERVED bit of its io_tree, and free the qgroup
+		 *    reserved data space.
+		 *    Since the IO will never happen for this page.
+		 */
+		btrfs_qgroup_free_data(inode, NULL, cur, range_end + 1 - cur, NULL);
+		if (!inode_evicting) {
+			clear_extent_bit(tree, cur, range_end, EXTENT_LOCKED |
+				 EXTENT_DELALLOC | EXTENT_UPTODATE |
+				 EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG |
+				 extra_flags, &cached_state);
+		}
+		cur = range_end + 1;
+	}
+	/*
+	 * We have iterated through all ordered extents of the page, the page
+	 * should not have Ordered (Private2) anymore, or the above iteration
+	 * did something wrong.
+	 */
+	ASSERT(!folio_test_ordered(folio));
+	btrfs_page_clear_checked(fs_info, &folio->page, folio_pos(folio), folio_size(folio));
+	if (!inode_evicting)
+		__btrfs_release_folio(folio, GFP_NOFS);
+	clear_page_extent_mapped(&folio->page);
+}
+
+/*
+ * btrfs_page_mkwrite() is not allowed to change the file size as it gets
+ * called from a page fault handler when a page is first dirtied. Hence we must
+ * be careful to check for EOF conditions here. We set the page up correctly
+ * for a written page which means we get ENOSPC checking when writing into
+ * holes and correct delalloc and unwritten extent mapping on filesystems that
+ * support these features.
+ *
+ * We are not allowed to take the i_mutex here so we have to play games to
+ * protect against truncate races as the page could now be beyond EOF.  Because
+ * truncate_setsize() writes the inode size before removing pages, once we have
+ * the page lock we can determine safely if the page is beyond EOF. If it is not
+ * beyond EOF, then the page is guaranteed safe against truncation until we
+ * unlock the page.
+ */
+vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct btrfs_ordered_extent *ordered;
+	struct extent_state *cached_state = NULL;
+	struct extent_changeset *data_reserved = NULL;
+	unsigned long zero_start;
+	loff_t size;
+	vm_fault_t ret;
+	int ret2;
+	int reserved = 0;
+	u64 reserved_space;
+	u64 page_start;
+	u64 page_end;
+	u64 end;
+
+	reserved_space = PAGE_SIZE;
+
+	sb_start_pagefault(inode->i_sb);
+	page_start = page_offset(page);
+	page_end = page_start + PAGE_SIZE - 1;
+	end = page_end;
+
+	/*
+	 * Reserving delalloc space after obtaining the page lock can lead to
+	 * deadlock. For example, if a dirty page is locked by this function
+	 * and the call to btrfs_delalloc_reserve_space() ends up triggering
+	 * dirty page write out, then the btrfs_writepages() function could
+	 * end up waiting indefinitely to get a lock on the page currently
+	 * being processed by btrfs_page_mkwrite() function.
+	 */
+	ret2 = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved,
+					    page_start, reserved_space);
+	if (!ret2) {
+		ret2 = file_update_time(vmf->vma->vm_file);
+		reserved = 1;
+	}
+	if (ret2) {
+		ret = vmf_error(ret2);
+		if (reserved)
+			goto out;
+		goto out_noreserve;
+	}
+
+	ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
+again:
+	down_read(&BTRFS_I(inode)->i_mmap_lock);
+	lock_page(page);
+	size = i_size_read(inode);
+
+	if ((page->mapping != inode->i_mapping) ||
+	    (page_start >= size)) {
+		/* page got truncated out from underneath us */
+		goto out_unlock;
+	}
+	wait_on_page_writeback(page);
+
+	lock_extent(io_tree, page_start, page_end, &cached_state);
+	ret2 = set_page_extent_mapped(page);
+	if (ret2 < 0) {
+		ret = vmf_error(ret2);
+		unlock_extent(io_tree, page_start, page_end, &cached_state);
+		goto out_unlock;
+	}
+
+	/*
+	 * we can't set the delalloc bits if there are pending ordered
+	 * extents.  Drop our locks and wait for them to finish
+	 */
+	ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start,
+			PAGE_SIZE);
+	if (ordered) {
+		unlock_extent(io_tree, page_start, page_end, &cached_state);
+		unlock_page(page);
+		up_read(&BTRFS_I(inode)->i_mmap_lock);
+		btrfs_start_ordered_extent(ordered);
+		btrfs_put_ordered_extent(ordered);
+		goto again;
+	}
+
+	if (page->index == ((size - 1) >> PAGE_SHIFT)) {
+		reserved_space = round_up(size - page_start,
+					  fs_info->sectorsize);
+		if (reserved_space < PAGE_SIZE) {
+			end = page_start + reserved_space - 1;
+			btrfs_delalloc_release_space(BTRFS_I(inode),
+					data_reserved, page_start,
+					PAGE_SIZE - reserved_space, true);
+		}
+	}
+
+	/*
+	 * page_mkwrite gets called when the page is firstly dirtied after it's
+	 * faulted in, but write(2) could also dirty a page and set delalloc
+	 * bits, thus in this case for space account reason, we still need to
+	 * clear any delalloc bits within this page range since we have to
+	 * reserve data&meta space before lock_page() (see above comments).
+	 */
+	clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end,
+			  EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
+			  EXTENT_DEFRAG, &cached_state);
+
+	ret2 = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start, end, 0,
+					&cached_state);
+	if (ret2) {
+		unlock_extent(io_tree, page_start, page_end, &cached_state);
+		ret = VM_FAULT_SIGBUS;
+		goto out_unlock;
+	}
+
+	/* page is wholly or partially inside EOF */
+	if (page_start + PAGE_SIZE > size)
+		zero_start = offset_in_page(size);
+	else
+		zero_start = PAGE_SIZE;
+
+	if (zero_start != PAGE_SIZE)
+		memzero_page(page, zero_start, PAGE_SIZE - zero_start);
+
+	btrfs_page_clear_checked(fs_info, page, page_start, PAGE_SIZE);
+	btrfs_page_set_dirty(fs_info, page, page_start, end + 1 - page_start);
+	btrfs_page_set_uptodate(fs_info, page, page_start, end + 1 - page_start);
+
+	btrfs_set_inode_last_sub_trans(BTRFS_I(inode));
+
+	unlock_extent(io_tree, page_start, page_end, &cached_state);
+	up_read(&BTRFS_I(inode)->i_mmap_lock);
+
+	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
+	sb_end_pagefault(inode->i_sb);
+	extent_changeset_free(data_reserved);
+	return VM_FAULT_LOCKED;
+
+out_unlock:
+	unlock_page(page);
+	up_read(&BTRFS_I(inode)->i_mmap_lock);
+out:
+	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
+	btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved, page_start,
+				     reserved_space, (ret != 0));
+out_noreserve:
+	sb_end_pagefault(inode->i_sb);
+	extent_changeset_free(data_reserved);
+	return ret;
+}
+
+static int btrfs_truncate(struct btrfs_inode *inode, bool skip_writeback)
+{
+	struct btrfs_truncate_control control = {
+		.inode = inode,
+		.ino = btrfs_ino(inode),
+		.min_type = BTRFS_EXTENT_DATA_KEY,
+		.clear_extent_range = true,
+	};
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_block_rsv *rsv;
+	int ret;
+	struct btrfs_trans_handle *trans;
+	u64 mask = fs_info->sectorsize - 1;
+	const u64 min_size = btrfs_calc_metadata_size(fs_info, 1);
+
+	if (!skip_writeback) {
+		ret = btrfs_wait_ordered_range(&inode->vfs_inode,
+					       inode->vfs_inode.i_size & (~mask),
+					       (u64)-1);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * Yes ladies and gentlemen, this is indeed ugly.  We have a couple of
+	 * things going on here:
+	 *
+	 * 1) We need to reserve space to update our inode.
+	 *
+	 * 2) We need to have something to cache all the space that is going to
+	 * be free'd up by the truncate operation, but also have some slack
+	 * space reserved in case it uses space during the truncate (thank you
+	 * very much snapshotting).
+	 *
+	 * And we need these to be separate.  The fact is we can use a lot of
+	 * space doing the truncate, and we have no earthly idea how much space
+	 * we will use, so we need the truncate reservation to be separate so it
+	 * doesn't end up using space reserved for updating the inode.  We also
+	 * need to be able to stop the transaction and start a new one, which
+	 * means we need to be able to update the inode several times, and we
+	 * have no idea of knowing how many times that will be, so we can't just
+	 * reserve 1 item for the entirety of the operation, so that has to be
+	 * done separately as well.
+	 *
+	 * So that leaves us with
+	 *
+	 * 1) rsv - for the truncate reservation, which we will steal from the
+	 * transaction reservation.
+	 * 2) fs_info->trans_block_rsv - this will have 1 items worth left for
+	 * updating the inode.
+	 */
+	rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
+	if (!rsv)
+		return -ENOMEM;
+	rsv->size = min_size;
+	rsv->failfast = true;
+
+	/*
+	 * 1 for the truncate slack space
+	 * 1 for updating the inode.
+	 */
+	trans = btrfs_start_transaction(root, 2);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	/* Migrate the slack space for the truncate to our reserve */
+	ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
+				      min_size, false);
+	/*
+	 * We have reserved 2 metadata units when we started the transaction and
+	 * min_size matches 1 unit, so this should never fail, but if it does,
+	 * it's not critical we just fail truncation.
+	 */
+	if (WARN_ON(ret)) {
+		btrfs_end_transaction(trans);
+		goto out;
+	}
+
+	trans->block_rsv = rsv;
+
+	while (1) {
+		struct extent_state *cached_state = NULL;
+		const u64 new_size = inode->vfs_inode.i_size;
+		const u64 lock_start = ALIGN_DOWN(new_size, fs_info->sectorsize);
+
+		control.new_size = new_size;
+		lock_extent(&inode->io_tree, lock_start, (u64)-1, &cached_state);
+		/*
+		 * We want to drop from the next block forward in case this new
+		 * size is not block aligned since we will be keeping the last
+		 * block of the extent just the way it is.
+		 */
+		btrfs_drop_extent_map_range(inode,
+					    ALIGN(new_size, fs_info->sectorsize),
+					    (u64)-1, false);
+
+		ret = btrfs_truncate_inode_items(trans, root, &control);
+
+		inode_sub_bytes(&inode->vfs_inode, control.sub_bytes);
+		btrfs_inode_safe_disk_i_size_write(inode, control.last_size);
+
+		unlock_extent(&inode->io_tree, lock_start, (u64)-1, &cached_state);
+
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		if (ret != -ENOSPC && ret != -EAGAIN)
+			break;
+
+		ret = btrfs_update_inode(trans, root, inode);
+		if (ret)
+			break;
+
+		btrfs_end_transaction(trans);
+		btrfs_btree_balance_dirty(fs_info);
+
+		trans = btrfs_start_transaction(root, 2);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			trans = NULL;
+			break;
+		}
+
+		btrfs_block_rsv_release(fs_info, rsv, -1, NULL);
+		ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
+					      rsv, min_size, false);
+		/*
+		 * We have reserved 2 metadata units when we started the
+		 * transaction and min_size matches 1 unit, so this should never
+		 * fail, but if it does, it's not critical we just fail truncation.
+		 */
+		if (WARN_ON(ret))
+			break;
+
+		trans->block_rsv = rsv;
+	}
+
+	/*
+	 * We can't call btrfs_truncate_block inside a trans handle as we could
+	 * deadlock with freeze, if we got BTRFS_NEED_TRUNCATE_BLOCK then we
+	 * know we've truncated everything except the last little bit, and can
+	 * do btrfs_truncate_block and then update the disk_i_size.
+	 */
+	if (ret == BTRFS_NEED_TRUNCATE_BLOCK) {
+		btrfs_end_transaction(trans);
+		btrfs_btree_balance_dirty(fs_info);
+
+		ret = btrfs_truncate_block(inode, inode->vfs_inode.i_size, 0, 0);
+		if (ret)
+			goto out;
+		trans = btrfs_start_transaction(root, 1);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			goto out;
+		}
+		btrfs_inode_safe_disk_i_size_write(inode, 0);
+	}
+
+	if (trans) {
+		int ret2;
+
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		ret2 = btrfs_update_inode(trans, root, inode);
+		if (ret2 && !ret)
+			ret = ret2;
+
+		ret2 = btrfs_end_transaction(trans);
+		if (ret2 && !ret)
+			ret = ret2;
+		btrfs_btree_balance_dirty(fs_info);
+	}
+out:
+	btrfs_free_block_rsv(fs_info, rsv);
+	/*
+	 * So if we truncate and then write and fsync we normally would just
+	 * write the extents that changed, which is a problem if we need to
+	 * first truncate that entire inode.  So set this flag so we write out
+	 * all of the extents in the inode to the sync log so we're completely
+	 * safe.
+	 *
+	 * If no extents were dropped or trimmed we don't need to force the next
+	 * fsync to truncate all the inode's items from the log and re-log them
+	 * all. This means the truncate operation did not change the file size,
+	 * or changed it to a smaller size but there was only an implicit hole
+	 * between the old i_size and the new i_size, and there were no prealloc
+	 * extents beyond i_size to drop.
+	 */
+	if (control.extents_found > 0)
+		btrfs_set_inode_full_sync(inode);
+
+	return ret;
+}
+
+struct inode *btrfs_new_subvol_inode(struct mnt_idmap *idmap,
+				     struct inode *dir)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (inode) {
+		/*
+		 * Subvolumes don't inherit the sgid bit or the parent's gid if
+		 * the parent's sgid bit is set. This is probably a bug.
+		 */
+		inode_init_owner(idmap, inode, NULL,
+				 S_IFDIR | (~current_umask() & S_IRWXUGO));
+		inode->i_op = &btrfs_dir_inode_operations;
+		inode->i_fop = &btrfs_dir_file_operations;
+	}
+	return inode;
+}
+
+struct inode *btrfs_alloc_inode(struct super_block *sb)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+	struct btrfs_inode *ei;
+	struct inode *inode;
+
+	ei = alloc_inode_sb(sb, btrfs_inode_cachep, GFP_KERNEL);
+	if (!ei)
+		return NULL;
+
+	ei->root = NULL;
+	ei->generation = 0;
+	ei->last_trans = 0;
+	ei->last_sub_trans = 0;
+	ei->logged_trans = 0;
+	ei->delalloc_bytes = 0;
+	ei->new_delalloc_bytes = 0;
+	ei->defrag_bytes = 0;
+	ei->disk_i_size = 0;
+	ei->flags = 0;
+	ei->ro_flags = 0;
+	ei->csum_bytes = 0;
+	ei->index_cnt = (u64)-1;
+	ei->dir_index = 0;
+	ei->last_unlink_trans = 0;
+	ei->last_reflink_trans = 0;
+	ei->last_log_commit = 0;
+
+	spin_lock_init(&ei->lock);
+	ei->outstanding_extents = 0;
+	if (sb->s_magic != BTRFS_TEST_MAGIC)
+		btrfs_init_metadata_block_rsv(fs_info, &ei->block_rsv,
+					      BTRFS_BLOCK_RSV_DELALLOC);
+	ei->runtime_flags = 0;
+	ei->prop_compress = BTRFS_COMPRESS_NONE;
+	ei->defrag_compress = BTRFS_COMPRESS_NONE;
+
+	ei->delayed_node = NULL;
+
+	ei->i_otime.tv_sec = 0;
+	ei->i_otime.tv_nsec = 0;
+
+	inode = &ei->vfs_inode;
+	extent_map_tree_init(&ei->extent_tree);
+	extent_io_tree_init(fs_info, &ei->io_tree, IO_TREE_INODE_IO);
+	ei->io_tree.inode = ei;
+	extent_io_tree_init(fs_info, &ei->file_extent_tree,
+			    IO_TREE_INODE_FILE_EXTENT);
+	mutex_init(&ei->log_mutex);
+	btrfs_ordered_inode_tree_init(&ei->ordered_tree);
+	INIT_LIST_HEAD(&ei->delalloc_inodes);
+	INIT_LIST_HEAD(&ei->delayed_iput);
+	RB_CLEAR_NODE(&ei->rb_node);
+	init_rwsem(&ei->i_mmap_lock);
+
+	return inode;
+}
+
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+void btrfs_test_destroy_inode(struct inode *inode)
+{
+	btrfs_drop_extent_map_range(BTRFS_I(inode), 0, (u64)-1, false);
+	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
+}
+#endif
+
+void btrfs_free_inode(struct inode *inode)
+{
+	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
+}
+
+void btrfs_destroy_inode(struct inode *vfs_inode)
+{
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_inode *inode = BTRFS_I(vfs_inode);
+	struct btrfs_root *root = inode->root;
+	bool freespace_inode;
+
+	WARN_ON(!hlist_empty(&vfs_inode->i_dentry));
+	WARN_ON(vfs_inode->i_data.nrpages);
+	WARN_ON(inode->block_rsv.reserved);
+	WARN_ON(inode->block_rsv.size);
+	WARN_ON(inode->outstanding_extents);
+	if (!S_ISDIR(vfs_inode->i_mode)) {
+		WARN_ON(inode->delalloc_bytes);
+		WARN_ON(inode->new_delalloc_bytes);
+	}
+	WARN_ON(inode->csum_bytes);
+	WARN_ON(inode->defrag_bytes);
+
+	/*
+	 * This can happen where we create an inode, but somebody else also
+	 * created the same inode and we need to destroy the one we already
+	 * created.
+	 */
+	if (!root)
+		return;
+
+	/*
+	 * If this is a free space inode do not take the ordered extents lockdep
+	 * map.
+	 */
+	freespace_inode = btrfs_is_free_space_inode(inode);
+
+	while (1) {
+		ordered = btrfs_lookup_first_ordered_extent(inode, (u64)-1);
+		if (!ordered)
+			break;
+		else {
+			btrfs_err(root->fs_info,
+				  "found ordered extent %llu %llu on inode cleanup",
+				  ordered->file_offset, ordered->num_bytes);
+
+			if (!freespace_inode)
+				btrfs_lockdep_acquire(root->fs_info, btrfs_ordered_extent);
+
+			btrfs_remove_ordered_extent(inode, ordered);
+			btrfs_put_ordered_extent(ordered);
+			btrfs_put_ordered_extent(ordered);
+		}
+	}
+	btrfs_qgroup_check_reserved_leak(inode);
+	inode_tree_del(inode);
+	btrfs_drop_extent_map_range(inode, 0, (u64)-1, false);
+	btrfs_inode_clear_file_extent_range(inode, 0, (u64)-1);
+	btrfs_put_root(inode->root);
+}
+
+int btrfs_drop_inode(struct inode *inode)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+
+	if (root == NULL)
+		return 1;
+
+	/* the snap/subvol tree is on deleting */
+	if (btrfs_root_refs(&root->root_item) == 0)
+		return 1;
+	else
+		return generic_drop_inode(inode);
+}
+
+static void init_once(void *foo)
+{
+	struct btrfs_inode *ei = foo;
+
+	inode_init_once(&ei->vfs_inode);
+}
+
+void __cold btrfs_destroy_cachep(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	bioset_exit(&btrfs_dio_bioset);
+	kmem_cache_destroy(btrfs_inode_cachep);
+}
+
+int __init btrfs_init_cachep(void)
+{
+	btrfs_inode_cachep = kmem_cache_create("btrfs_inode",
+			sizeof(struct btrfs_inode), 0,
+			SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD | SLAB_ACCOUNT,
+			init_once);
+	if (!btrfs_inode_cachep)
+		goto fail;
+
+	if (bioset_init(&btrfs_dio_bioset, BIO_POOL_SIZE,
+			offsetof(struct btrfs_dio_private, bbio.bio),
+			BIOSET_NEED_BVECS))
+		goto fail;
+
+	return 0;
+fail:
+	btrfs_destroy_cachep();
+	return -ENOMEM;
+}
+
+static int btrfs_getattr(struct mnt_idmap *idmap,
+			 const struct path *path, struct kstat *stat,
+			 u32 request_mask, unsigned int flags)
+{
+	u64 delalloc_bytes;
+	u64 inode_bytes;
+	struct inode *inode = d_inode(path->dentry);
+	u32 blocksize = inode->i_sb->s_blocksize;
+	u32 bi_flags = BTRFS_I(inode)->flags;
+	u32 bi_ro_flags = BTRFS_I(inode)->ro_flags;
+
+	stat->result_mask |= STATX_BTIME;
+	stat->btime.tv_sec = BTRFS_I(inode)->i_otime.tv_sec;
+	stat->btime.tv_nsec = BTRFS_I(inode)->i_otime.tv_nsec;
+	if (bi_flags & BTRFS_INODE_APPEND)
+		stat->attributes |= STATX_ATTR_APPEND;
+	if (bi_flags & BTRFS_INODE_COMPRESS)
+		stat->attributes |= STATX_ATTR_COMPRESSED;
+	if (bi_flags & BTRFS_INODE_IMMUTABLE)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	if (bi_flags & BTRFS_INODE_NODUMP)
+		stat->attributes |= STATX_ATTR_NODUMP;
+	if (bi_ro_flags & BTRFS_INODE_RO_VERITY)
+		stat->attributes |= STATX_ATTR_VERITY;
+
+	stat->attributes_mask |= (STATX_ATTR_APPEND |
+				  STATX_ATTR_COMPRESSED |
+				  STATX_ATTR_IMMUTABLE |
+				  STATX_ATTR_NODUMP);
+
+	generic_fillattr(idmap, request_mask, inode, stat);
+	stat->dev = BTRFS_I(inode)->root->anon_dev;
+
+	spin_lock(&BTRFS_I(inode)->lock);
+	delalloc_bytes = BTRFS_I(inode)->new_delalloc_bytes;
+	inode_bytes = inode_get_bytes(inode);
+	spin_unlock(&BTRFS_I(inode)->lock);
+	stat->blocks = (ALIGN(inode_bytes, blocksize) +
+			ALIGN(delalloc_bytes, blocksize)) >> SECTOR_SHIFT;
+	return 0;
+}
+
+static int btrfs_rename_exchange(struct inode *old_dir,
+			      struct dentry *old_dentry,
+			      struct inode *new_dir,
+			      struct dentry *new_dentry)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(old_dir->i_sb);
+	struct btrfs_trans_handle *trans;
+	unsigned int trans_num_items;
+	struct btrfs_root *root = BTRFS_I(old_dir)->root;
+	struct btrfs_root *dest = BTRFS_I(new_dir)->root;
+	struct inode *new_inode = new_dentry->d_inode;
+	struct inode *old_inode = old_dentry->d_inode;
+	struct btrfs_rename_ctx old_rename_ctx;
+	struct btrfs_rename_ctx new_rename_ctx;
+	u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
+	u64 new_ino = btrfs_ino(BTRFS_I(new_inode));
+	u64 old_idx = 0;
+	u64 new_idx = 0;
+	int ret;
+	int ret2;
+	bool need_abort = false;
+	struct fscrypt_name old_fname, new_fname;
+	struct fscrypt_str *old_name, *new_name;
+
+	/*
+	 * For non-subvolumes allow exchange only within one subvolume, in the
+	 * same inode namespace. Two subvolumes (represented as directory) can
+	 * be exchanged as they're a logical link and have a fixed inode number.
+	 */
+	if (root != dest &&
+	    (old_ino != BTRFS_FIRST_FREE_OBJECTID ||
+	     new_ino != BTRFS_FIRST_FREE_OBJECTID))
+		return -EXDEV;
+
+	ret = fscrypt_setup_filename(old_dir, &old_dentry->d_name, 0, &old_fname);
+	if (ret)
+		return ret;
+
+	ret = fscrypt_setup_filename(new_dir, &new_dentry->d_name, 0, &new_fname);
+	if (ret) {
+		fscrypt_free_filename(&old_fname);
+		return ret;
+	}
+
+	old_name = &old_fname.disk_name;
+	new_name = &new_fname.disk_name;
+
+	/* close the race window with snapshot create/destroy ioctl */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    new_ino == BTRFS_FIRST_FREE_OBJECTID)
+		down_read(&fs_info->subvol_sem);
+
+	/*
+	 * For each inode:
+	 * 1 to remove old dir item
+	 * 1 to remove old dir index
+	 * 1 to add new dir item
+	 * 1 to add new dir index
+	 * 1 to update parent inode
+	 *
+	 * If the parents are the same, we only need to account for one
+	 */
+	trans_num_items = (old_dir == new_dir ? 9 : 10);
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/*
+		 * 1 to remove old root ref
+		 * 1 to remove old root backref
+		 * 1 to add new root ref
+		 * 1 to add new root backref
+		 */
+		trans_num_items += 4;
+	} else {
+		/*
+		 * 1 to update inode item
+		 * 1 to remove old inode ref
+		 * 1 to add new inode ref
+		 */
+		trans_num_items += 3;
+	}
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
+		trans_num_items += 4;
+	else
+		trans_num_items += 3;
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_notrans;
+	}
+
+	if (dest != root) {
+		ret = btrfs_record_root_in_trans(trans, dest);
+		if (ret)
+			goto out_fail;
+	}
+
+	/*
+	 * We need to find a free sequence number both in the source and
+	 * in the destination directory for the exchange.
+	 */
+	ret = btrfs_set_inode_index(BTRFS_I(new_dir), &old_idx);
+	if (ret)
+		goto out_fail;
+	ret = btrfs_set_inode_index(BTRFS_I(old_dir), &new_idx);
+	if (ret)
+		goto out_fail;
+
+	BTRFS_I(old_inode)->dir_index = 0ULL;
+	BTRFS_I(new_inode)->dir_index = 0ULL;
+
+	/* Reference for the source. */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/* force full log commit if subvolume involved. */
+		btrfs_set_log_full_commit(trans);
+	} else {
+		ret = btrfs_insert_inode_ref(trans, dest, new_name, old_ino,
+					     btrfs_ino(BTRFS_I(new_dir)),
+					     old_idx);
+		if (ret)
+			goto out_fail;
+		need_abort = true;
+	}
+
+	/* And now for the dest. */
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/* force full log commit if subvolume involved. */
+		btrfs_set_log_full_commit(trans);
+	} else {
+		ret = btrfs_insert_inode_ref(trans, root, old_name, new_ino,
+					     btrfs_ino(BTRFS_I(old_dir)),
+					     new_idx);
+		if (ret) {
+			if (need_abort)
+				btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	}
+
+	/* Update inode version and ctime/mtime. */
+	inode_inc_iversion(old_dir);
+	inode_inc_iversion(new_dir);
+	inode_inc_iversion(old_inode);
+	inode_inc_iversion(new_inode);
+	simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
+
+	if (old_dentry->d_parent != new_dentry->d_parent) {
+		btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
+					BTRFS_I(old_inode), true);
+		btrfs_record_unlink_dir(trans, BTRFS_I(new_dir),
+					BTRFS_I(new_inode), true);
+	}
+
+	/* src is a subvolume */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		ret = btrfs_unlink_subvol(trans, BTRFS_I(old_dir), old_dentry);
+	} else { /* src is an inode */
+		ret = __btrfs_unlink_inode(trans, BTRFS_I(old_dir),
+					   BTRFS_I(old_dentry->d_inode),
+					   old_name, &old_rename_ctx);
+		if (!ret)
+			ret = btrfs_update_inode(trans, root, BTRFS_I(old_inode));
+	}
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	/* dest is a subvolume */
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		ret = btrfs_unlink_subvol(trans, BTRFS_I(new_dir), new_dentry);
+	} else { /* dest is an inode */
+		ret = __btrfs_unlink_inode(trans, BTRFS_I(new_dir),
+					   BTRFS_I(new_dentry->d_inode),
+					   new_name, &new_rename_ctx);
+		if (!ret)
+			ret = btrfs_update_inode(trans, dest, BTRFS_I(new_inode));
+	}
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	ret = btrfs_add_link(trans, BTRFS_I(new_dir), BTRFS_I(old_inode),
+			     new_name, 0, old_idx);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	ret = btrfs_add_link(trans, BTRFS_I(old_dir), BTRFS_I(new_inode),
+			     old_name, 0, new_idx);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	if (old_inode->i_nlink == 1)
+		BTRFS_I(old_inode)->dir_index = old_idx;
+	if (new_inode->i_nlink == 1)
+		BTRFS_I(new_inode)->dir_index = new_idx;
+
+	/*
+	 * Now pin the logs of the roots. We do it to ensure that no other task
+	 * can sync the logs while we are in progress with the rename, because
+	 * that could result in an inconsistency in case any of the inodes that
+	 * are part of this rename operation were logged before.
+	 */
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
+		btrfs_pin_log_trans(root);
+	if (new_ino != BTRFS_FIRST_FREE_OBJECTID)
+		btrfs_pin_log_trans(dest);
+
+	/* Do the log updates for all inodes. */
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
+		btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
+				   old_rename_ctx.index, new_dentry->d_parent);
+	if (new_ino != BTRFS_FIRST_FREE_OBJECTID)
+		btrfs_log_new_name(trans, new_dentry, BTRFS_I(new_dir),
+				   new_rename_ctx.index, old_dentry->d_parent);
+
+	/* Now unpin the logs. */
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
+		btrfs_end_log_trans(root);
+	if (new_ino != BTRFS_FIRST_FREE_OBJECTID)
+		btrfs_end_log_trans(dest);
+out_fail:
+	ret2 = btrfs_end_transaction(trans);
+	ret = ret ? ret : ret2;
+out_notrans:
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    old_ino == BTRFS_FIRST_FREE_OBJECTID)
+		up_read(&fs_info->subvol_sem);
+
+	fscrypt_free_filename(&new_fname);
+	fscrypt_free_filename(&old_fname);
+	return ret;
+}
+
+static struct inode *new_whiteout_inode(struct mnt_idmap *idmap,
+					struct inode *dir)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (inode) {
+		inode_init_owner(idmap, inode, dir,
+				 S_IFCHR | WHITEOUT_MODE);
+		inode->i_op = &btrfs_special_inode_operations;
+		init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
+	}
+	return inode;
+}
+
+static int btrfs_rename(struct mnt_idmap *idmap,
+			struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir, struct dentry *new_dentry,
+			unsigned int flags)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(old_dir->i_sb);
+	struct btrfs_new_inode_args whiteout_args = {
+		.dir = old_dir,
+		.dentry = old_dentry,
+	};
+	struct btrfs_trans_handle *trans;
+	unsigned int trans_num_items;
+	struct btrfs_root *root = BTRFS_I(old_dir)->root;
+	struct btrfs_root *dest = BTRFS_I(new_dir)->root;
+	struct inode *new_inode = d_inode(new_dentry);
+	struct inode *old_inode = d_inode(old_dentry);
+	struct btrfs_rename_ctx rename_ctx;
+	u64 index = 0;
+	int ret;
+	int ret2;
+	u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
+	struct fscrypt_name old_fname, new_fname;
+
+	if (btrfs_ino(BTRFS_I(new_dir)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
+		return -EPERM;
+
+	/* we only allow rename subvolume link between subvolumes */
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID && root != dest)
+		return -EXDEV;
+
+	if (old_ino == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID ||
+	    (new_inode && btrfs_ino(BTRFS_I(new_inode)) == BTRFS_FIRST_FREE_OBJECTID))
+		return -ENOTEMPTY;
+
+	if (S_ISDIR(old_inode->i_mode) && new_inode &&
+	    new_inode->i_size > BTRFS_EMPTY_DIR_SIZE)
+		return -ENOTEMPTY;
+
+	ret = fscrypt_setup_filename(old_dir, &old_dentry->d_name, 0, &old_fname);
+	if (ret)
+		return ret;
+
+	ret = fscrypt_setup_filename(new_dir, &new_dentry->d_name, 0, &new_fname);
+	if (ret) {
+		fscrypt_free_filename(&old_fname);
+		return ret;
+	}
+
+	/* check for collisions, even if the  name isn't there */
+	ret = btrfs_check_dir_item_collision(dest, new_dir->i_ino, &new_fname.disk_name);
+	if (ret) {
+		if (ret == -EEXIST) {
+			/* we shouldn't get
+			 * eexist without a new_inode */
+			if (WARN_ON(!new_inode)) {
+				goto out_fscrypt_names;
+			}
+		} else {
+			/* maybe -EOVERFLOW */
+			goto out_fscrypt_names;
+		}
+	}
+	ret = 0;
+
+	/*
+	 * we're using rename to replace one file with another.  Start IO on it
+	 * now so  we don't add too much work to the end of the transaction
+	 */
+	if (new_inode && S_ISREG(old_inode->i_mode) && new_inode->i_size)
+		filemap_flush(old_inode->i_mapping);
+
+	if (flags & RENAME_WHITEOUT) {
+		whiteout_args.inode = new_whiteout_inode(idmap, old_dir);
+		if (!whiteout_args.inode) {
+			ret = -ENOMEM;
+			goto out_fscrypt_names;
+		}
+		ret = btrfs_new_inode_prepare(&whiteout_args, &trans_num_items);
+		if (ret)
+			goto out_whiteout_inode;
+	} else {
+		/* 1 to update the old parent inode. */
+		trans_num_items = 1;
+	}
+
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/* Close the race window with snapshot create/destroy ioctl */
+		down_read(&fs_info->subvol_sem);
+		/*
+		 * 1 to remove old root ref
+		 * 1 to remove old root backref
+		 * 1 to add new root ref
+		 * 1 to add new root backref
+		 */
+		trans_num_items += 4;
+	} else {
+		/*
+		 * 1 to update inode
+		 * 1 to remove old inode ref
+		 * 1 to add new inode ref
+		 */
+		trans_num_items += 3;
+	}
+	/*
+	 * 1 to remove old dir item
+	 * 1 to remove old dir index
+	 * 1 to add new dir item
+	 * 1 to add new dir index
+	 */
+	trans_num_items += 4;
+	/* 1 to update new parent inode if it's not the same as the old parent */
+	if (new_dir != old_dir)
+		trans_num_items++;
+	if (new_inode) {
+		/*
+		 * 1 to update inode
+		 * 1 to remove inode ref
+		 * 1 to remove dir item
+		 * 1 to remove dir index
+		 * 1 to possibly add orphan item
+		 */
+		trans_num_items += 5;
+	}
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_notrans;
+	}
+
+	if (dest != root) {
+		ret = btrfs_record_root_in_trans(trans, dest);
+		if (ret)
+			goto out_fail;
+	}
+
+	ret = btrfs_set_inode_index(BTRFS_I(new_dir), &index);
+	if (ret)
+		goto out_fail;
+
+	BTRFS_I(old_inode)->dir_index = 0ULL;
+	if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		/* force full log commit if subvolume involved. */
+		btrfs_set_log_full_commit(trans);
+	} else {
+		ret = btrfs_insert_inode_ref(trans, dest, &new_fname.disk_name,
+					     old_ino, btrfs_ino(BTRFS_I(new_dir)),
+					     index);
+		if (ret)
+			goto out_fail;
+	}
+
+	inode_inc_iversion(old_dir);
+	inode_inc_iversion(new_dir);
+	inode_inc_iversion(old_inode);
+	simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
+
+	if (old_dentry->d_parent != new_dentry->d_parent)
+		btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
+					BTRFS_I(old_inode), true);
+
+	if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		ret = btrfs_unlink_subvol(trans, BTRFS_I(old_dir), old_dentry);
+	} else {
+		ret = __btrfs_unlink_inode(trans, BTRFS_I(old_dir),
+					   BTRFS_I(d_inode(old_dentry)),
+					   &old_fname.disk_name, &rename_ctx);
+		if (!ret)
+			ret = btrfs_update_inode(trans, root, BTRFS_I(old_inode));
+	}
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	if (new_inode) {
+		inode_inc_iversion(new_inode);
+		if (unlikely(btrfs_ino(BTRFS_I(new_inode)) ==
+			     BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
+			ret = btrfs_unlink_subvol(trans, BTRFS_I(new_dir), new_dentry);
+			BUG_ON(new_inode->i_nlink == 0);
+		} else {
+			ret = btrfs_unlink_inode(trans, BTRFS_I(new_dir),
+						 BTRFS_I(d_inode(new_dentry)),
+						 &new_fname.disk_name);
+		}
+		if (!ret && new_inode->i_nlink == 0)
+			ret = btrfs_orphan_add(trans,
+					BTRFS_I(d_inode(new_dentry)));
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	}
+
+	ret = btrfs_add_link(trans, BTRFS_I(new_dir), BTRFS_I(old_inode),
+			     &new_fname.disk_name, 0, index);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	if (old_inode->i_nlink == 1)
+		BTRFS_I(old_inode)->dir_index = index;
+
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
+		btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
+				   rename_ctx.index, new_dentry->d_parent);
+
+	if (flags & RENAME_WHITEOUT) {
+		ret = btrfs_create_new_inode(trans, &whiteout_args);
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		} else {
+			unlock_new_inode(whiteout_args.inode);
+			iput(whiteout_args.inode);
+			whiteout_args.inode = NULL;
+		}
+	}
+out_fail:
+	ret2 = btrfs_end_transaction(trans);
+	ret = ret ? ret : ret2;
+out_notrans:
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+		up_read(&fs_info->subvol_sem);
+	if (flags & RENAME_WHITEOUT)
+		btrfs_new_inode_args_destroy(&whiteout_args);
+out_whiteout_inode:
+	if (flags & RENAME_WHITEOUT)
+		iput(whiteout_args.inode);
+out_fscrypt_names:
+	fscrypt_free_filename(&old_fname);
+	fscrypt_free_filename(&new_fname);
+	return ret;
+}
+
+static int btrfs_rename2(struct mnt_idmap *idmap, struct inode *old_dir,
+			 struct dentry *old_dentry, struct inode *new_dir,
+			 struct dentry *new_dentry, unsigned int flags)
+{
+	int ret;
+
+	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
+		return -EINVAL;
+
+	if (flags & RENAME_EXCHANGE)
+		ret = btrfs_rename_exchange(old_dir, old_dentry, new_dir,
+					    new_dentry);
+	else
+		ret = btrfs_rename(idmap, old_dir, old_dentry, new_dir,
+				   new_dentry, flags);
+
+	btrfs_btree_balance_dirty(BTRFS_I(new_dir)->root->fs_info);
+
+	return ret;
+}
+
+struct btrfs_delalloc_work {
+	struct inode *inode;
+	struct completion completion;
+	struct list_head list;
+	struct btrfs_work work;
+};
+
+static void btrfs_run_delalloc_work(struct btrfs_work *work)
+{
+	struct btrfs_delalloc_work *delalloc_work;
+	struct inode *inode;
+
+	delalloc_work = container_of(work, struct btrfs_delalloc_work,
+				     work);
+	inode = delalloc_work->inode;
+	filemap_flush(inode->i_mapping);
+	if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+				&BTRFS_I(inode)->runtime_flags))
+		filemap_flush(inode->i_mapping);
+
+	iput(inode);
+	complete(&delalloc_work->completion);
+}
+
+static struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode)
+{
+	struct btrfs_delalloc_work *work;
+
+	work = kmalloc(sizeof(*work), GFP_NOFS);
+	if (!work)
+		return NULL;
+
+	init_completion(&work->completion);
+	INIT_LIST_HEAD(&work->list);
+	work->inode = inode;
+	btrfs_init_work(&work->work, btrfs_run_delalloc_work, NULL, NULL);
+
+	return work;
+}
+
+/*
+ * some fairly slow code that needs optimization. This walks the list
+ * of all the inodes with pending delalloc and forces them to disk.
+ */
+static int start_delalloc_inodes(struct btrfs_root *root,
+				 struct writeback_control *wbc, bool snapshot,
+				 bool in_reclaim_context)
+{
+	struct btrfs_inode *binode;
+	struct inode *inode;
+	struct btrfs_delalloc_work *work, *next;
+	LIST_HEAD(works);
+	LIST_HEAD(splice);
+	int ret = 0;
+	bool full_flush = wbc->nr_to_write == LONG_MAX;
+
+	mutex_lock(&root->delalloc_mutex);
+	spin_lock(&root->delalloc_lock);
+	list_splice_init(&root->delalloc_inodes, &splice);
+	while (!list_empty(&splice)) {
+		binode = list_entry(splice.next, struct btrfs_inode,
+				    delalloc_inodes);
+
+		list_move_tail(&binode->delalloc_inodes,
+			       &root->delalloc_inodes);
+
+		if (in_reclaim_context &&
+		    test_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &binode->runtime_flags))
+			continue;
+
+		inode = igrab(&binode->vfs_inode);
+		if (!inode) {
+			cond_resched_lock(&root->delalloc_lock);
+			continue;
+		}
+		spin_unlock(&root->delalloc_lock);
+
+		if (snapshot)
+			set_bit(BTRFS_INODE_SNAPSHOT_FLUSH,
+				&binode->runtime_flags);
+		if (full_flush) {
+			work = btrfs_alloc_delalloc_work(inode);
+			if (!work) {
+				iput(inode);
+				ret = -ENOMEM;
+				goto out;
+			}
+			list_add_tail(&work->list, &works);
+			btrfs_queue_work(root->fs_info->flush_workers,
+					 &work->work);
+		} else {
+			ret = filemap_fdatawrite_wbc(inode->i_mapping, wbc);
+			btrfs_add_delayed_iput(BTRFS_I(inode));
+			if (ret || wbc->nr_to_write <= 0)
+				goto out;
+		}
+		cond_resched();
+		spin_lock(&root->delalloc_lock);
+	}
+	spin_unlock(&root->delalloc_lock);
+
+out:
+	list_for_each_entry_safe(work, next, &works, list) {
+		list_del_init(&work->list);
+		wait_for_completion(&work->completion);
+		kfree(work);
+	}
+
+	if (!list_empty(&splice)) {
+		spin_lock(&root->delalloc_lock);
+		list_splice_tail(&splice, &root->delalloc_inodes);
+		spin_unlock(&root->delalloc_lock);
+	}
+	mutex_unlock(&root->delalloc_mutex);
+	return ret;
+}
+
+int btrfs_start_delalloc_snapshot(struct btrfs_root *root, bool in_reclaim_context)
+{
+	struct writeback_control wbc = {
+		.nr_to_write = LONG_MAX,
+		.sync_mode = WB_SYNC_NONE,
+		.range_start = 0,
+		.range_end = LLONG_MAX,
+	};
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	if (BTRFS_FS_ERROR(fs_info))
+		return -EROFS;
+
+	return start_delalloc_inodes(root, &wbc, true, in_reclaim_context);
+}
+
+int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, long nr,
+			       bool in_reclaim_context)
+{
+	struct writeback_control wbc = {
+		.nr_to_write = nr,
+		.sync_mode = WB_SYNC_NONE,
+		.range_start = 0,
+		.range_end = LLONG_MAX,
+	};
+	struct btrfs_root *root;
+	LIST_HEAD(splice);
+	int ret;
+
+	if (BTRFS_FS_ERROR(fs_info))
+		return -EROFS;
+
+	mutex_lock(&fs_info->delalloc_root_mutex);
+	spin_lock(&fs_info->delalloc_root_lock);
+	list_splice_init(&fs_info->delalloc_roots, &splice);
+	while (!list_empty(&splice)) {
+		/*
+		 * Reset nr_to_write here so we know that we're doing a full
+		 * flush.
+		 */
+		if (nr == LONG_MAX)
+			wbc.nr_to_write = LONG_MAX;
+
+		root = list_first_entry(&splice, struct btrfs_root,
+					delalloc_root);
+		root = btrfs_grab_root(root);
+		BUG_ON(!root);
+		list_move_tail(&root->delalloc_root,
+			       &fs_info->delalloc_roots);
+		spin_unlock(&fs_info->delalloc_root_lock);
+
+		ret = start_delalloc_inodes(root, &wbc, false, in_reclaim_context);
+		btrfs_put_root(root);
+		if (ret < 0 || wbc.nr_to_write <= 0)
+			goto out;
+		spin_lock(&fs_info->delalloc_root_lock);
+	}
+	spin_unlock(&fs_info->delalloc_root_lock);
+
+	ret = 0;
+out:
+	if (!list_empty(&splice)) {
+		spin_lock(&fs_info->delalloc_root_lock);
+		list_splice_tail(&splice, &fs_info->delalloc_roots);
+		spin_unlock(&fs_info->delalloc_root_lock);
+	}
+	mutex_unlock(&fs_info->delalloc_root_mutex);
+	return ret;
+}
+
+static int btrfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
+			 struct dentry *dentry, const char *symname)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	struct inode *inode;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = dentry,
+	};
+	unsigned int trans_num_items;
+	int err;
+	int name_len;
+	int datasize;
+	unsigned long ptr;
+	struct btrfs_file_extent_item *ei;
+	struct extent_buffer *leaf;
+
+	name_len = strlen(symname);
+	if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info))
+		return -ENAMETOOLONG;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, S_IFLNK | S_IRWXUGO);
+	inode->i_op = &btrfs_symlink_inode_operations;
+	inode_nohighmem(inode);
+	inode->i_mapping->a_ops = &btrfs_aops;
+	btrfs_i_size_write(BTRFS_I(inode), name_len);
+	inode_set_bytes(inode, name_len);
+
+	new_inode_args.inode = inode;
+	err = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (err)
+		goto out_inode;
+	/* 1 additional item for the inline extent */
+	trans_num_items++;
+
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		err = PTR_ERR(trans);
+		goto out_new_inode_args;
+	}
+
+	err = btrfs_create_new_inode(trans, &new_inode_args);
+	if (err)
+		goto out;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		err = -ENOMEM;
+		btrfs_abort_transaction(trans, err);
+		discard_new_inode(inode);
+		inode = NULL;
+		goto out;
+	}
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+	key.offset = 0;
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	datasize = btrfs_file_extent_calc_inline_size(name_len);
+	err = btrfs_insert_empty_item(trans, root, path, &key,
+				      datasize);
+	if (err) {
+		btrfs_abort_transaction(trans, err);
+		btrfs_free_path(path);
+		discard_new_inode(inode);
+		inode = NULL;
+		goto out;
+	}
+	leaf = path->nodes[0];
+	ei = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, ei, trans->transid);
+	btrfs_set_file_extent_type(leaf, ei,
+				   BTRFS_FILE_EXTENT_INLINE);
+	btrfs_set_file_extent_encryption(leaf, ei, 0);
+	btrfs_set_file_extent_compression(leaf, ei, 0);
+	btrfs_set_file_extent_other_encoding(leaf, ei, 0);
+	btrfs_set_file_extent_ram_bytes(leaf, ei, name_len);
+
+	ptr = btrfs_file_extent_inline_start(ei);
+	write_extent_buffer(leaf, symname, ptr, name_len);
+	btrfs_mark_buffer_dirty(trans, leaf);
+	btrfs_free_path(path);
+
+	d_instantiate_new(dentry, inode);
+	err = 0;
+out:
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
+out_inode:
+	if (err)
+		iput(inode);
+	return err;
+}
+
+static struct btrfs_trans_handle *insert_prealloc_file_extent(
+				       struct btrfs_trans_handle *trans_in,
+				       struct btrfs_inode *inode,
+				       struct btrfs_key *ins,
+				       u64 file_offset)
+{
+	struct btrfs_file_extent_item stack_fi;
+	struct btrfs_replace_extent_info extent_info;
+	struct btrfs_trans_handle *trans = trans_in;
+	struct btrfs_path *path;
+	u64 start = ins->objectid;
+	u64 len = ins->offset;
+	u64 qgroup_released = 0;
+	int ret;
+
+	memset(&stack_fi, 0, sizeof(stack_fi));
+
+	btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_PREALLOC);
+	btrfs_set_stack_file_extent_disk_bytenr(&stack_fi, start);
+	btrfs_set_stack_file_extent_disk_num_bytes(&stack_fi, len);
+	btrfs_set_stack_file_extent_num_bytes(&stack_fi, len);
+	btrfs_set_stack_file_extent_ram_bytes(&stack_fi, len);
+	btrfs_set_stack_file_extent_compression(&stack_fi, BTRFS_COMPRESS_NONE);
+	/* Encryption and other encoding is reserved and all 0 */
+
+	ret = btrfs_qgroup_release_data(inode, file_offset, len, &qgroup_released);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (trans) {
+		ret = insert_reserved_file_extent(trans, inode,
+						  file_offset, &stack_fi,
+						  true, qgroup_released);
+		if (ret)
+			goto free_qgroup;
+		return trans;
+	}
+
+	extent_info.disk_offset = start;
+	extent_info.disk_len = len;
+	extent_info.data_offset = 0;
+	extent_info.data_len = len;
+	extent_info.file_offset = file_offset;
+	extent_info.extent_buf = (char *)&stack_fi;
+	extent_info.is_new_extent = true;
+	extent_info.update_times = true;
+	extent_info.qgroup_reserved = qgroup_released;
+	extent_info.insertions = 0;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto free_qgroup;
+	}
+
+	ret = btrfs_replace_file_extents(inode, path, file_offset,
+				     file_offset + len - 1, &extent_info,
+				     &trans);
+	btrfs_free_path(path);
+	if (ret)
+		goto free_qgroup;
+	return trans;
+
+free_qgroup:
+	/*
+	 * We have released qgroup data range at the beginning of the function,
+	 * and normally qgroup_released bytes will be freed when committing
+	 * transaction.
+	 * But if we error out early, we have to free what we have released
+	 * or we leak qgroup data reservation.
+	 */
+	btrfs_qgroup_free_refroot(inode->root->fs_info,
+			inode->root->root_key.objectid, qgroup_released,
+			BTRFS_QGROUP_RSV_DATA);
+	return ERR_PTR(ret);
+}
+
+static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
+				       u64 start, u64 num_bytes, u64 min_size,
+				       loff_t actual_len, u64 *alloc_hint,
+				       struct btrfs_trans_handle *trans)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct extent_map *em;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_key ins;
+	u64 cur_offset = start;
+	u64 clear_offset = start;
+	u64 i_size;
+	u64 cur_bytes;
+	u64 last_alloc = (u64)-1;
+	int ret = 0;
+	bool own_trans = true;
+	u64 end = start + num_bytes - 1;
+
+	if (trans)
+		own_trans = false;
+	while (num_bytes > 0) {
+		cur_bytes = min_t(u64, num_bytes, SZ_256M);
+		cur_bytes = max(cur_bytes, min_size);
+		/*
+		 * If we are severely fragmented we could end up with really
+		 * small allocations, so if the allocator is returning small
+		 * chunks lets make its job easier by only searching for those
+		 * sized chunks.
+		 */
+		cur_bytes = min(cur_bytes, last_alloc);
+		ret = btrfs_reserve_extent(root, cur_bytes, cur_bytes,
+				min_size, 0, *alloc_hint, &ins, 1, 0);
+		if (ret)
+			break;
+
+		/*
+		 * We've reserved this space, and thus converted it from
+		 * ->bytes_may_use to ->bytes_reserved.  Any error that happens
+		 * from here on out we will only need to clear our reservation
+		 * for the remaining unreserved area, so advance our
+		 * clear_offset by our extent size.
+		 */
+		clear_offset += ins.offset;
+
+		last_alloc = ins.offset;
+		trans = insert_prealloc_file_extent(trans, BTRFS_I(inode),
+						    &ins, cur_offset);
+		/*
+		 * Now that we inserted the prealloc extent we can finally
+		 * decrement the number of reservations in the block group.
+		 * If we did it before, we could race with relocation and have
+		 * relocation miss the reserved extent, making it fail later.
+		 */
+		btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			btrfs_free_reserved_extent(fs_info, ins.objectid,
+						   ins.offset, 0);
+			break;
+		}
+
+		em = alloc_extent_map();
+		if (!em) {
+			btrfs_drop_extent_map_range(BTRFS_I(inode), cur_offset,
+					    cur_offset + ins.offset - 1, false);
+			btrfs_set_inode_full_sync(BTRFS_I(inode));
+			goto next;
+		}
+
+		em->start = cur_offset;
+		em->orig_start = cur_offset;
+		em->len = ins.offset;
+		em->block_start = ins.objectid;
+		em->block_len = ins.offset;
+		em->orig_block_len = ins.offset;
+		em->ram_bytes = ins.offset;
+		set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
+		em->generation = trans->transid;
+
+		ret = btrfs_replace_extent_map_range(BTRFS_I(inode), em, true);
+		free_extent_map(em);
+next:
+		num_bytes -= ins.offset;
+		cur_offset += ins.offset;
+		*alloc_hint = ins.objectid + ins.offset;
+
+		inode_inc_iversion(inode);
+		inode_set_ctime_current(inode);
+		BTRFS_I(inode)->flags |= BTRFS_INODE_PREALLOC;
+		if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+		    (actual_len > inode->i_size) &&
+		    (cur_offset > inode->i_size)) {
+			if (cur_offset > actual_len)
+				i_size = actual_len;
+			else
+				i_size = cur_offset;
+			i_size_write(inode, i_size);
+			btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
+		}
+
+		ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
+
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			if (own_trans)
+				btrfs_end_transaction(trans);
+			break;
+		}
+
+		if (own_trans) {
+			btrfs_end_transaction(trans);
+			trans = NULL;
+		}
+	}
+	if (clear_offset < end)
+		btrfs_free_reserved_data_space(BTRFS_I(inode), NULL, clear_offset,
+			end - clear_offset + 1);
+	return ret;
+}
+
+int btrfs_prealloc_file_range(struct inode *inode, int mode,
+			      u64 start, u64 num_bytes, u64 min_size,
+			      loff_t actual_len, u64 *alloc_hint)
+{
+	return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+					   min_size, actual_len, alloc_hint,
+					   NULL);
+}
+
+int btrfs_prealloc_file_range_trans(struct inode *inode,
+				    struct btrfs_trans_handle *trans, int mode,
+				    u64 start, u64 num_bytes, u64 min_size,
+				    loff_t actual_len, u64 *alloc_hint)
+{
+	return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+					   min_size, actual_len, alloc_hint, trans);
+}
+
+static int btrfs_permission(struct mnt_idmap *idmap,
+			    struct inode *inode, int mask)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	umode_t mode = inode->i_mode;
+
+	if (mask & MAY_WRITE &&
+	    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) {
+		if (btrfs_root_readonly(root))
+			return -EROFS;
+		if (BTRFS_I(inode)->flags & BTRFS_INODE_READONLY)
+			return -EACCES;
+	}
+	return generic_permission(idmap, inode, mask);
+}
+
+static int btrfs_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
+			 struct file *file, umode_t mode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct inode *inode;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = file->f_path.dentry,
+		.orphan = true,
+	};
+	unsigned int trans_num_items;
+	int ret;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, mode);
+	inode->i_fop = &btrfs_file_operations;
+	inode->i_op = &btrfs_file_inode_operations;
+	inode->i_mapping->a_ops = &btrfs_aops;
+
+	new_inode_args.inode = inode;
+	ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (ret)
+		goto out_inode;
+
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_new_inode_args;
+	}
+
+	ret = btrfs_create_new_inode(trans, &new_inode_args);
+
+	/*
+	 * We set number of links to 0 in btrfs_create_new_inode(), and here we
+	 * set it to 1 because d_tmpfile() will issue a warning if the count is
+	 * 0, through:
+	 *
+	 *    d_tmpfile() -> inode_dec_link_count() -> drop_nlink()
+	 */
+	set_nlink(inode, 1);
+
+	if (!ret) {
+		d_tmpfile(file, inode);
+		unlock_new_inode(inode);
+		mark_inode_dirty(inode);
+	}
+
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
+out_inode:
+	if (ret)
+		iput(inode);
+	return finish_open_simple(file, ret);
+}
+
+void btrfs_set_range_writeback(struct btrfs_inode *inode, u64 start, u64 end)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	unsigned long index = start >> PAGE_SHIFT;
+	unsigned long end_index = end >> PAGE_SHIFT;
+	struct page *page;
+	u32 len;
+
+	ASSERT(end + 1 - start <= U32_MAX);
+	len = end + 1 - start;
+	while (index <= end_index) {
+		page = find_get_page(inode->vfs_inode.i_mapping, index);
+		ASSERT(page); /* Pages should be in the extent_io_tree */
+
+		btrfs_page_set_writeback(fs_info, page, start, len);
+		put_page(page);
+		index++;
+	}
+}
+
+int btrfs_encoded_io_compression_from_extent(struct btrfs_fs_info *fs_info,
+					     int compress_type)
+{
+	switch (compress_type) {
+	case BTRFS_COMPRESS_NONE:
+		return BTRFS_ENCODED_IO_COMPRESSION_NONE;
+	case BTRFS_COMPRESS_ZLIB:
+		return BTRFS_ENCODED_IO_COMPRESSION_ZLIB;
+	case BTRFS_COMPRESS_LZO:
+		/*
+		 * The LZO format depends on the sector size. 64K is the maximum
+		 * sector size that we support.
+		 */
+		if (fs_info->sectorsize < SZ_4K || fs_info->sectorsize > SZ_64K)
+			return -EINVAL;
+		return BTRFS_ENCODED_IO_COMPRESSION_LZO_4K +
+		       (fs_info->sectorsize_bits - 12);
+	case BTRFS_COMPRESS_ZSTD:
+		return BTRFS_ENCODED_IO_COMPRESSION_ZSTD;
+	default:
+		return -EUCLEAN;
+	}
+}
+
+static ssize_t btrfs_encoded_read_inline(
+				struct kiocb *iocb,
+				struct iov_iter *iter, u64 start,
+				u64 lockend,
+				struct extent_state **cached_state,
+				u64 extent_start, size_t count,
+				struct btrfs_ioctl_encoded_io_args *encoded,
+				bool *unlocked)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *item;
+	u64 ram_bytes;
+	unsigned long ptr;
+	void *tmp;
+	ssize_t ret;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode),
+				       extent_start, 0);
+	if (ret) {
+		if (ret > 0) {
+			/* The extent item disappeared? */
+			ret = -EIO;
+		}
+		goto out;
+	}
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
+
+	ram_bytes = btrfs_file_extent_ram_bytes(leaf, item);
+	ptr = btrfs_file_extent_inline_start(item);
+
+	encoded->len = min_t(u64, extent_start + ram_bytes,
+			     inode->vfs_inode.i_size) - iocb->ki_pos;
+	ret = btrfs_encoded_io_compression_from_extent(fs_info,
+				 btrfs_file_extent_compression(leaf, item));
+	if (ret < 0)
+		goto out;
+	encoded->compression = ret;
+	if (encoded->compression) {
+		size_t inline_size;
+
+		inline_size = btrfs_file_extent_inline_item_len(leaf,
+								path->slots[0]);
+		if (inline_size > count) {
+			ret = -ENOBUFS;
+			goto out;
+		}
+		count = inline_size;
+		encoded->unencoded_len = ram_bytes;
+		encoded->unencoded_offset = iocb->ki_pos - extent_start;
+	} else {
+		count = min_t(u64, count, encoded->len);
+		encoded->len = count;
+		encoded->unencoded_len = count;
+		ptr += iocb->ki_pos - extent_start;
+	}
+
+	tmp = kmalloc(count, GFP_NOFS);
+	if (!tmp) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	read_extent_buffer(leaf, tmp, ptr, count);
+	btrfs_release_path(path);
+	unlock_extent(io_tree, start, lockend, cached_state);
+	btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+	*unlocked = true;
+
+	ret = copy_to_iter(tmp, count, iter);
+	if (ret != count)
+		ret = -EFAULT;
+	kfree(tmp);
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+struct btrfs_encoded_read_private {
+	wait_queue_head_t wait;
+	atomic_t pending;
+	blk_status_t status;
+};
+
+static void btrfs_encoded_read_endio(struct btrfs_bio *bbio)
+{
+	struct btrfs_encoded_read_private *priv = bbio->private;
+
+	if (bbio->bio.bi_status) {
+		/*
+		 * The memory barrier implied by the atomic_dec_return() here
+		 * pairs with the memory barrier implied by the
+		 * atomic_dec_return() or io_wait_event() in
+		 * btrfs_encoded_read_regular_fill_pages() to ensure that this
+		 * write is observed before the load of status in
+		 * btrfs_encoded_read_regular_fill_pages().
+		 */
+		WRITE_ONCE(priv->status, bbio->bio.bi_status);
+	}
+	if (!atomic_dec_return(&priv->pending))
+		wake_up(&priv->wait);
+	bio_put(&bbio->bio);
+}
+
+int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
+					  u64 file_offset, u64 disk_bytenr,
+					  u64 disk_io_size, struct page **pages)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_encoded_read_private priv = {
+		.pending = ATOMIC_INIT(1),
+	};
+	unsigned long i = 0;
+	struct btrfs_bio *bbio;
+
+	init_waitqueue_head(&priv.wait);
+
+	bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, fs_info,
+			       btrfs_encoded_read_endio, &priv);
+	bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
+	bbio->inode = inode;
+
+	do {
+		size_t bytes = min_t(u64, disk_io_size, PAGE_SIZE);
+
+		if (bio_add_page(&bbio->bio, pages[i], bytes, 0) < bytes) {
+			atomic_inc(&priv.pending);
+			btrfs_submit_bio(bbio, 0);
+
+			bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, fs_info,
+					       btrfs_encoded_read_endio, &priv);
+			bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
+			bbio->inode = inode;
+			continue;
+		}
+
+		i++;
+		disk_bytenr += bytes;
+		disk_io_size -= bytes;
+	} while (disk_io_size);
+
+	atomic_inc(&priv.pending);
+	btrfs_submit_bio(bbio, 0);
+
+	if (atomic_dec_return(&priv.pending))
+		io_wait_event(priv.wait, !atomic_read(&priv.pending));
+	/* See btrfs_encoded_read_endio() for ordering. */
+	return blk_status_to_errno(READ_ONCE(priv.status));
+}
+
+static ssize_t btrfs_encoded_read_regular(struct kiocb *iocb,
+					  struct iov_iter *iter,
+					  u64 start, u64 lockend,
+					  struct extent_state **cached_state,
+					  u64 disk_bytenr, u64 disk_io_size,
+					  size_t count, bool compressed,
+					  bool *unlocked)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct page **pages;
+	unsigned long nr_pages, i;
+	u64 cur;
+	size_t page_offset;
+	ssize_t ret;
+
+	nr_pages = DIV_ROUND_UP(disk_io_size, PAGE_SIZE);
+	pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
+	if (!pages)
+		return -ENOMEM;
+	ret = btrfs_alloc_page_array(nr_pages, pages);
+	if (ret) {
+		ret = -ENOMEM;
+		goto out;
+		}
+
+	ret = btrfs_encoded_read_regular_fill_pages(inode, start, disk_bytenr,
+						    disk_io_size, pages);
+	if (ret)
+		goto out;
+
+	unlock_extent(io_tree, start, lockend, cached_state);
+	btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+	*unlocked = true;
+
+	if (compressed) {
+		i = 0;
+		page_offset = 0;
+	} else {
+		i = (iocb->ki_pos - start) >> PAGE_SHIFT;
+		page_offset = (iocb->ki_pos - start) & (PAGE_SIZE - 1);
+	}
+	cur = 0;
+	while (cur < count) {
+		size_t bytes = min_t(size_t, count - cur,
+				     PAGE_SIZE - page_offset);
+
+		if (copy_page_to_iter(pages[i], page_offset, bytes,
+				      iter) != bytes) {
+			ret = -EFAULT;
+			goto out;
+		}
+		i++;
+		cur += bytes;
+		page_offset = 0;
+	}
+	ret = count;
+out:
+	for (i = 0; i < nr_pages; i++) {
+		if (pages[i])
+			__free_page(pages[i]);
+	}
+	kfree(pages);
+	return ret;
+}
+
+ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter,
+			   struct btrfs_ioctl_encoded_io_args *encoded)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	ssize_t ret;
+	size_t count = iov_iter_count(iter);
+	u64 start, lockend, disk_bytenr, disk_io_size;
+	struct extent_state *cached_state = NULL;
+	struct extent_map *em;
+	bool unlocked = false;
+
+	file_accessed(iocb->ki_filp);
+
+	btrfs_inode_lock(inode, BTRFS_ILOCK_SHARED);
+
+	if (iocb->ki_pos >= inode->vfs_inode.i_size) {
+		btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+		return 0;
+	}
+	start = ALIGN_DOWN(iocb->ki_pos, fs_info->sectorsize);
+	/*
+	 * We don't know how long the extent containing iocb->ki_pos is, but if
+	 * it's compressed we know that it won't be longer than this.
+	 */
+	lockend = start + BTRFS_MAX_UNCOMPRESSED - 1;
+
+	for (;;) {
+		struct btrfs_ordered_extent *ordered;
+
+		ret = btrfs_wait_ordered_range(&inode->vfs_inode, start,
+					       lockend - start + 1);
+		if (ret)
+			goto out_unlock_inode;
+		lock_extent(io_tree, start, lockend, &cached_state);
+		ordered = btrfs_lookup_ordered_range(inode, start,
+						     lockend - start + 1);
+		if (!ordered)
+			break;
+		btrfs_put_ordered_extent(ordered);
+		unlock_extent(io_tree, start, lockend, &cached_state);
+		cond_resched();
+	}
+
+	em = btrfs_get_extent(inode, NULL, 0, start, lockend - start + 1);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out_unlock_extent;
+	}
+
+	if (em->block_start == EXTENT_MAP_INLINE) {
+		u64 extent_start = em->start;
+
+		/*
+		 * For inline extents we get everything we need out of the
+		 * extent item.
+		 */
+		free_extent_map(em);
+		em = NULL;
+		ret = btrfs_encoded_read_inline(iocb, iter, start, lockend,
+						&cached_state, extent_start,
+						count, encoded, &unlocked);
+		goto out;
+	}
+
+	/*
+	 * We only want to return up to EOF even if the extent extends beyond
+	 * that.
+	 */
+	encoded->len = min_t(u64, extent_map_end(em),
+			     inode->vfs_inode.i_size) - iocb->ki_pos;
+	if (em->block_start == EXTENT_MAP_HOLE ||
+	    test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
+		disk_bytenr = EXTENT_MAP_HOLE;
+		count = min_t(u64, count, encoded->len);
+		encoded->len = count;
+		encoded->unencoded_len = count;
+	} else if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
+		disk_bytenr = em->block_start;
+		/*
+		 * Bail if the buffer isn't large enough to return the whole
+		 * compressed extent.
+		 */
+		if (em->block_len > count) {
+			ret = -ENOBUFS;
+			goto out_em;
+		}
+		disk_io_size = em->block_len;
+		count = em->block_len;
+		encoded->unencoded_len = em->ram_bytes;
+		encoded->unencoded_offset = iocb->ki_pos - em->orig_start;
+		ret = btrfs_encoded_io_compression_from_extent(fs_info,
+							     em->compress_type);
+		if (ret < 0)
+			goto out_em;
+		encoded->compression = ret;
+	} else {
+		disk_bytenr = em->block_start + (start - em->start);
+		if (encoded->len > count)
+			encoded->len = count;
+		/*
+		 * Don't read beyond what we locked. This also limits the page
+		 * allocations that we'll do.
+		 */
+		disk_io_size = min(lockend + 1, iocb->ki_pos + encoded->len) - start;
+		count = start + disk_io_size - iocb->ki_pos;
+		encoded->len = count;
+		encoded->unencoded_len = count;
+		disk_io_size = ALIGN(disk_io_size, fs_info->sectorsize);
+	}
+	free_extent_map(em);
+	em = NULL;
+
+	if (disk_bytenr == EXTENT_MAP_HOLE) {
+		unlock_extent(io_tree, start, lockend, &cached_state);
+		btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+		unlocked = true;
+		ret = iov_iter_zero(count, iter);
+		if (ret != count)
+			ret = -EFAULT;
+	} else {
+		ret = btrfs_encoded_read_regular(iocb, iter, start, lockend,
+						 &cached_state, disk_bytenr,
+						 disk_io_size, count,
+						 encoded->compression,
+						 &unlocked);
+	}
+
+out:
+	if (ret >= 0)
+		iocb->ki_pos += encoded->len;
+out_em:
+	free_extent_map(em);
+out_unlock_extent:
+	if (!unlocked)
+		unlock_extent(io_tree, start, lockend, &cached_state);
+out_unlock_inode:
+	if (!unlocked)
+		btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+	return ret;
+}
+
+ssize_t btrfs_do_encoded_write(struct kiocb *iocb, struct iov_iter *from,
+			       const struct btrfs_ioctl_encoded_io_args *encoded)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct extent_changeset *data_reserved = NULL;
+	struct extent_state *cached_state = NULL;
+	struct btrfs_ordered_extent *ordered;
+	int compression;
+	size_t orig_count;
+	u64 start, end;
+	u64 num_bytes, ram_bytes, disk_num_bytes;
+	unsigned long nr_pages, i;
+	struct page **pages;
+	struct btrfs_key ins;
+	bool extent_reserved = false;
+	struct extent_map *em;
+	ssize_t ret;
+
+	switch (encoded->compression) {
+	case BTRFS_ENCODED_IO_COMPRESSION_ZLIB:
+		compression = BTRFS_COMPRESS_ZLIB;
+		break;
+	case BTRFS_ENCODED_IO_COMPRESSION_ZSTD:
+		compression = BTRFS_COMPRESS_ZSTD;
+		break;
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_4K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_8K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_16K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_32K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_64K:
+		/* The sector size must match for LZO. */
+		if (encoded->compression -
+		    BTRFS_ENCODED_IO_COMPRESSION_LZO_4K + 12 !=
+		    fs_info->sectorsize_bits)
+			return -EINVAL;
+		compression = BTRFS_COMPRESS_LZO;
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (encoded->encryption != BTRFS_ENCODED_IO_ENCRYPTION_NONE)
+		return -EINVAL;
+
+	orig_count = iov_iter_count(from);
+
+	/* The extent size must be sane. */
+	if (encoded->unencoded_len > BTRFS_MAX_UNCOMPRESSED ||
+	    orig_count > BTRFS_MAX_COMPRESSED || orig_count == 0)
+		return -EINVAL;
+
+	/*
+	 * The compressed data must be smaller than the decompressed data.
+	 *
+	 * It's of course possible for data to compress to larger or the same
+	 * size, but the buffered I/O path falls back to no compression for such
+	 * data, and we don't want to break any assumptions by creating these
+	 * extents.
+	 *
+	 * Note that this is less strict than the current check we have that the
+	 * compressed data must be at least one sector smaller than the
+	 * decompressed data. We only want to enforce the weaker requirement
+	 * from old kernels that it is at least one byte smaller.
+	 */
+	if (orig_count >= encoded->unencoded_len)
+		return -EINVAL;
+
+	/* The extent must start on a sector boundary. */
+	start = iocb->ki_pos;
+	if (!IS_ALIGNED(start, fs_info->sectorsize))
+		return -EINVAL;
+
+	/*
+	 * The extent must end on a sector boundary. However, we allow a write
+	 * which ends at or extends i_size to have an unaligned length; we round
+	 * up the extent size and set i_size to the unaligned end.
+	 */
+	if (start + encoded->len < inode->vfs_inode.i_size &&
+	    !IS_ALIGNED(start + encoded->len, fs_info->sectorsize))
+		return -EINVAL;
+
+	/* Finally, the offset in the unencoded data must be sector-aligned. */
+	if (!IS_ALIGNED(encoded->unencoded_offset, fs_info->sectorsize))
+		return -EINVAL;
+
+	num_bytes = ALIGN(encoded->len, fs_info->sectorsize);
+	ram_bytes = ALIGN(encoded->unencoded_len, fs_info->sectorsize);
+	end = start + num_bytes - 1;
+
+	/*
+	 * If the extent cannot be inline, the compressed data on disk must be
+	 * sector-aligned. For convenience, we extend it with zeroes if it
+	 * isn't.
+	 */
+	disk_num_bytes = ALIGN(orig_count, fs_info->sectorsize);
+	nr_pages = DIV_ROUND_UP(disk_num_bytes, PAGE_SIZE);
+	pages = kvcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL_ACCOUNT);
+	if (!pages)
+		return -ENOMEM;
+	for (i = 0; i < nr_pages; i++) {
+		size_t bytes = min_t(size_t, PAGE_SIZE, iov_iter_count(from));
+		char *kaddr;
+
+		pages[i] = alloc_page(GFP_KERNEL_ACCOUNT);
+		if (!pages[i]) {
+			ret = -ENOMEM;
+			goto out_pages;
+		}
+		kaddr = kmap_local_page(pages[i]);
+		if (copy_from_iter(kaddr, bytes, from) != bytes) {
+			kunmap_local(kaddr);
+			ret = -EFAULT;
+			goto out_pages;
+		}
+		if (bytes < PAGE_SIZE)
+			memset(kaddr + bytes, 0, PAGE_SIZE - bytes);
+		kunmap_local(kaddr);
+	}
+
+	for (;;) {
+		struct btrfs_ordered_extent *ordered;
+
+		ret = btrfs_wait_ordered_range(&inode->vfs_inode, start, num_bytes);
+		if (ret)
+			goto out_pages;
+		ret = invalidate_inode_pages2_range(inode->vfs_inode.i_mapping,
+						    start >> PAGE_SHIFT,
+						    end >> PAGE_SHIFT);
+		if (ret)
+			goto out_pages;
+		lock_extent(io_tree, start, end, &cached_state);
+		ordered = btrfs_lookup_ordered_range(inode, start, num_bytes);
+		if (!ordered &&
+		    !filemap_range_has_page(inode->vfs_inode.i_mapping, start, end))
+			break;
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+		unlock_extent(io_tree, start, end, &cached_state);
+		cond_resched();
+	}
+
+	/*
+	 * We don't use the higher-level delalloc space functions because our
+	 * num_bytes and disk_num_bytes are different.
+	 */
+	ret = btrfs_alloc_data_chunk_ondemand(inode, disk_num_bytes);
+	if (ret)
+		goto out_unlock;
+	ret = btrfs_qgroup_reserve_data(inode, &data_reserved, start, num_bytes);
+	if (ret)
+		goto out_free_data_space;
+	ret = btrfs_delalloc_reserve_metadata(inode, num_bytes, disk_num_bytes,
+					      false);
+	if (ret)
+		goto out_qgroup_free_data;
+
+	/* Try an inline extent first. */
+	if (start == 0 && encoded->unencoded_len == encoded->len &&
+	    encoded->unencoded_offset == 0) {
+		ret = cow_file_range_inline(inode, encoded->len, orig_count,
+					    compression, pages, true);
+		if (ret <= 0) {
+			if (ret == 0)
+				ret = orig_count;
+			goto out_delalloc_release;
+		}
+	}
+
+	ret = btrfs_reserve_extent(root, disk_num_bytes, disk_num_bytes,
+				   disk_num_bytes, 0, 0, &ins, 1, 1);
+	if (ret)
+		goto out_delalloc_release;
+	extent_reserved = true;
+
+	em = create_io_em(inode, start, num_bytes,
+			  start - encoded->unencoded_offset, ins.objectid,
+			  ins.offset, ins.offset, ram_bytes, compression,
+			  BTRFS_ORDERED_COMPRESSED);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out_free_reserved;
+	}
+	free_extent_map(em);
+
+	ordered = btrfs_alloc_ordered_extent(inode, start, num_bytes, ram_bytes,
+				       ins.objectid, ins.offset,
+				       encoded->unencoded_offset,
+				       (1 << BTRFS_ORDERED_ENCODED) |
+				       (1 << BTRFS_ORDERED_COMPRESSED),
+				       compression);
+	if (IS_ERR(ordered)) {
+		btrfs_drop_extent_map_range(inode, start, end, false);
+		ret = PTR_ERR(ordered);
+		goto out_free_reserved;
+	}
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+
+	if (start + encoded->len > inode->vfs_inode.i_size)
+		i_size_write(&inode->vfs_inode, start + encoded->len);
+
+	unlock_extent(io_tree, start, end, &cached_state);
+
+	btrfs_delalloc_release_extents(inode, num_bytes);
+
+	btrfs_submit_compressed_write(ordered, pages, nr_pages, 0, false);
+	ret = orig_count;
+	goto out;
+
+out_free_reserved:
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
+out_delalloc_release:
+	btrfs_delalloc_release_extents(inode, num_bytes);
+	btrfs_delalloc_release_metadata(inode, disk_num_bytes, ret < 0);
+out_qgroup_free_data:
+	if (ret < 0)
+		btrfs_qgroup_free_data(inode, data_reserved, start, num_bytes, NULL);
+out_free_data_space:
+	/*
+	 * If btrfs_reserve_extent() succeeded, then we already decremented
+	 * bytes_may_use.
+	 */
+	if (!extent_reserved)
+		btrfs_free_reserved_data_space_noquota(fs_info, disk_num_bytes);
+out_unlock:
+	unlock_extent(io_tree, start, end, &cached_state);
+out_pages:
+	for (i = 0; i < nr_pages; i++) {
+		if (pages[i])
+			__free_page(pages[i]);
+	}
+	kvfree(pages);
+out:
+	if (ret >= 0)
+		iocb->ki_pos += encoded->len;
+	return ret;
+}
+
+#ifdef CONFIG_SWAP
+/*
+ * Add an entry indicating a block group or device which is pinned by a
+ * swapfile. Returns 0 on success, 1 if there is already an entry for it, or a
+ * negative errno on failure.
+ */
+static int btrfs_add_swapfile_pin(struct inode *inode, void *ptr,
+				  bool is_block_group)
+{
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+	struct btrfs_swapfile_pin *sp, *entry;
+	struct rb_node **p;
+	struct rb_node *parent = NULL;
+
+	sp = kmalloc(sizeof(*sp), GFP_NOFS);
+	if (!sp)
+		return -ENOMEM;
+	sp->ptr = ptr;
+	sp->inode = inode;
+	sp->is_block_group = is_block_group;
+	sp->bg_extent_count = 1;
+
+	spin_lock(&fs_info->swapfile_pins_lock);
+	p = &fs_info->swapfile_pins.rb_node;
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct btrfs_swapfile_pin, node);
+		if (sp->ptr < entry->ptr ||
+		    (sp->ptr == entry->ptr && sp->inode < entry->inode)) {
+			p = &(*p)->rb_left;
+		} else if (sp->ptr > entry->ptr ||
+			   (sp->ptr == entry->ptr && sp->inode > entry->inode)) {
+			p = &(*p)->rb_right;
+		} else {
+			if (is_block_group)
+				entry->bg_extent_count++;
+			spin_unlock(&fs_info->swapfile_pins_lock);
+			kfree(sp);
+			return 1;
+		}
+	}
+	rb_link_node(&sp->node, parent, p);
+	rb_insert_color(&sp->node, &fs_info->swapfile_pins);
+	spin_unlock(&fs_info->swapfile_pins_lock);
+	return 0;
+}
+
+/* Free all of the entries pinned by this swapfile. */
+static void btrfs_free_swapfile_pins(struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+	struct btrfs_swapfile_pin *sp;
+	struct rb_node *node, *next;
+
+	spin_lock(&fs_info->swapfile_pins_lock);
+	node = rb_first(&fs_info->swapfile_pins);
+	while (node) {
+		next = rb_next(node);
+		sp = rb_entry(node, struct btrfs_swapfile_pin, node);
+		if (sp->inode == inode) {
+			rb_erase(&sp->node, &fs_info->swapfile_pins);
+			if (sp->is_block_group) {
+				btrfs_dec_block_group_swap_extents(sp->ptr,
+							   sp->bg_extent_count);
+				btrfs_put_block_group(sp->ptr);
+			}
+			kfree(sp);
+		}
+		node = next;
+	}
+	spin_unlock(&fs_info->swapfile_pins_lock);
+}
+
+struct btrfs_swap_info {
+	u64 start;
+	u64 block_start;
+	u64 block_len;
+	u64 lowest_ppage;
+	u64 highest_ppage;
+	unsigned long nr_pages;
+	int nr_extents;
+};
+
+static int btrfs_add_swap_extent(struct swap_info_struct *sis,
+				 struct btrfs_swap_info *bsi)
+{
+	unsigned long nr_pages;
+	unsigned long max_pages;
+	u64 first_ppage, first_ppage_reported, next_ppage;
+	int ret;
+
+	/*
+	 * Our swapfile may have had its size extended after the swap header was
+	 * written. In that case activating the swapfile should not go beyond
+	 * the max size set in the swap header.
+	 */
+	if (bsi->nr_pages >= sis->max)
+		return 0;
+
+	max_pages = sis->max - bsi->nr_pages;
+	first_ppage = PAGE_ALIGN(bsi->block_start) >> PAGE_SHIFT;
+	next_ppage = PAGE_ALIGN_DOWN(bsi->block_start + bsi->block_len) >> PAGE_SHIFT;
+
+	if (first_ppage >= next_ppage)
+		return 0;
+	nr_pages = next_ppage - first_ppage;
+	nr_pages = min(nr_pages, max_pages);
+
+	first_ppage_reported = first_ppage;
+	if (bsi->start == 0)
+		first_ppage_reported++;
+	if (bsi->lowest_ppage > first_ppage_reported)
+		bsi->lowest_ppage = first_ppage_reported;
+	if (bsi->highest_ppage < (next_ppage - 1))
+		bsi->highest_ppage = next_ppage - 1;
+
+	ret = add_swap_extent(sis, bsi->nr_pages, nr_pages, first_ppage);
+	if (ret < 0)
+		return ret;
+	bsi->nr_extents += ret;
+	bsi->nr_pages += nr_pages;
+	return 0;
+}
+
+static void btrfs_swap_deactivate(struct file *file)
+{
+	struct inode *inode = file_inode(file);
+
+	btrfs_free_swapfile_pins(inode);
+	atomic_dec(&BTRFS_I(inode)->root->nr_swapfiles);
+}
+
+static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
+			       sector_t *span)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_state *cached_state = NULL;
+	struct extent_map *em = NULL;
+	struct btrfs_device *device = NULL;
+	struct btrfs_swap_info bsi = {
+		.lowest_ppage = (sector_t)-1ULL,
+	};
+	int ret = 0;
+	u64 isize;
+	u64 start;
+
+	/*
+	 * If the swap file was just created, make sure delalloc is done. If the
+	 * file changes again after this, the user is doing something stupid and
+	 * we don't really care.
+	 */
+	ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
+	if (ret)
+		return ret;
+
+	/*
+	 * The inode is locked, so these flags won't change after we check them.
+	 */
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS) {
+		btrfs_warn(fs_info, "swapfile must not be compressed");
+		return -EINVAL;
+	}
+	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW)) {
+		btrfs_warn(fs_info, "swapfile must not be copy-on-write");
+		return -EINVAL;
+	}
+	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
+		btrfs_warn(fs_info, "swapfile must not be checksummed");
+		return -EINVAL;
+	}
+
+	/*
+	 * Balance or device remove/replace/resize can move stuff around from
+	 * under us. The exclop protection makes sure they aren't running/won't
+	 * run concurrently while we are mapping the swap extents, and
+	 * fs_info->swapfile_pins prevents them from running while the swap
+	 * file is active and moving the extents. Note that this also prevents
+	 * a concurrent device add which isn't actually necessary, but it's not
+	 * really worth the trouble to allow it.
+	 */
+	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_SWAP_ACTIVATE)) {
+		btrfs_warn(fs_info,
+	   "cannot activate swapfile while exclusive operation is running");
+		return -EBUSY;
+	}
+
+	/*
+	 * Prevent snapshot creation while we are activating the swap file.
+	 * We do not want to race with snapshot creation. If snapshot creation
+	 * already started before we bumped nr_swapfiles from 0 to 1 and
+	 * completes before the first write into the swap file after it is
+	 * activated, than that write would fallback to COW.
+	 */
+	if (!btrfs_drew_try_write_lock(&root->snapshot_lock)) {
+		btrfs_exclop_finish(fs_info);
+		btrfs_warn(fs_info,
+	   "cannot activate swapfile because snapshot creation is in progress");
+		return -EINVAL;
+	}
+	/*
+	 * Snapshots can create extents which require COW even if NODATACOW is
+	 * set. We use this counter to prevent snapshots. We must increment it
+	 * before walking the extents because we don't want a concurrent
+	 * snapshot to run after we've already checked the extents.
+	 *
+	 * It is possible that subvolume is marked for deletion but still not
+	 * removed yet. To prevent this race, we check the root status before
+	 * activating the swapfile.
+	 */
+	spin_lock(&root->root_item_lock);
+	if (btrfs_root_dead(root)) {
+		spin_unlock(&root->root_item_lock);
+
+		btrfs_exclop_finish(fs_info);
+		btrfs_warn(fs_info,
+		"cannot activate swapfile because subvolume %llu is being deleted",
+			root->root_key.objectid);
+		return -EPERM;
+	}
+	atomic_inc(&root->nr_swapfiles);
+	spin_unlock(&root->root_item_lock);
+
+	isize = ALIGN_DOWN(inode->i_size, fs_info->sectorsize);
+
+	lock_extent(io_tree, 0, isize - 1, &cached_state);
+	start = 0;
+	while (start < isize) {
+		u64 logical_block_start, physical_block_start;
+		struct btrfs_block_group *bg;
+		u64 len = isize - start;
+
+		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			goto out;
+		}
+
+		if (em->block_start == EXTENT_MAP_HOLE) {
+			btrfs_warn(fs_info, "swapfile must not have holes");
+			ret = -EINVAL;
+			goto out;
+		}
+		if (em->block_start == EXTENT_MAP_INLINE) {
+			/*
+			 * It's unlikely we'll ever actually find ourselves
+			 * here, as a file small enough to fit inline won't be
+			 * big enough to store more than the swap header, but in
+			 * case something changes in the future, let's catch it
+			 * here rather than later.
+			 */
+			btrfs_warn(fs_info, "swapfile must not be inline");
+			ret = -EINVAL;
+			goto out;
+		}
+		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
+			btrfs_warn(fs_info, "swapfile must not be compressed");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		logical_block_start = em->block_start + (start - em->start);
+		len = min(len, em->len - (start - em->start));
+		free_extent_map(em);
+		em = NULL;
+
+		ret = can_nocow_extent(inode, start, &len, NULL, NULL, NULL, false, true);
+		if (ret < 0) {
+			goto out;
+		} else if (ret) {
+			ret = 0;
+		} else {
+			btrfs_warn(fs_info,
+				   "swapfile must not be copy-on-write");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		em = btrfs_get_chunk_map(fs_info, logical_block_start, len);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			goto out;
+		}
+
+		if (em->map_lookup->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
+			btrfs_warn(fs_info,
+				   "swapfile must have single data profile");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (device == NULL) {
+			device = em->map_lookup->stripes[0].dev;
+			ret = btrfs_add_swapfile_pin(inode, device, false);
+			if (ret == 1)
+				ret = 0;
+			else if (ret)
+				goto out;
+		} else if (device != em->map_lookup->stripes[0].dev) {
+			btrfs_warn(fs_info, "swapfile must be on one device");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		physical_block_start = (em->map_lookup->stripes[0].physical +
+					(logical_block_start - em->start));
+		len = min(len, em->len - (logical_block_start - em->start));
+		free_extent_map(em);
+		em = NULL;
+
+		bg = btrfs_lookup_block_group(fs_info, logical_block_start);
+		if (!bg) {
+			btrfs_warn(fs_info,
+			   "could not find block group containing swapfile");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (!btrfs_inc_block_group_swap_extents(bg)) {
+			btrfs_warn(fs_info,
+			   "block group for swapfile at %llu is read-only%s",
+			   bg->start,
+			   atomic_read(&fs_info->scrubs_running) ?
+				       " (scrub running)" : "");
+			btrfs_put_block_group(bg);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = btrfs_add_swapfile_pin(inode, bg, true);
+		if (ret) {
+			btrfs_put_block_group(bg);
+			if (ret == 1)
+				ret = 0;
+			else
+				goto out;
+		}
+
+		if (bsi.block_len &&
+		    bsi.block_start + bsi.block_len == physical_block_start) {
+			bsi.block_len += len;
+		} else {
+			if (bsi.block_len) {
+				ret = btrfs_add_swap_extent(sis, &bsi);
+				if (ret)
+					goto out;
+			}
+			bsi.start = start;
+			bsi.block_start = physical_block_start;
+			bsi.block_len = len;
+		}
+
+		start += len;
+	}
+
+	if (bsi.block_len)
+		ret = btrfs_add_swap_extent(sis, &bsi);
+
+out:
+	if (!IS_ERR_OR_NULL(em))
+		free_extent_map(em);
+
+	unlock_extent(io_tree, 0, isize - 1, &cached_state);
+
+	if (ret)
+		btrfs_swap_deactivate(file);
+
+	btrfs_drew_write_unlock(&root->snapshot_lock);
+
+	btrfs_exclop_finish(fs_info);
+
+	if (ret)
+		return ret;
+
+	if (device)
+		sis->bdev = device->bdev;
+	*span = bsi.highest_ppage - bsi.lowest_ppage + 1;
+	sis->max = bsi.nr_pages;
+	sis->pages = bsi.nr_pages - 1;
+	sis->highest_bit = bsi.nr_pages - 1;
+	return bsi.nr_extents;
+}
+#else
+static void btrfs_swap_deactivate(struct file *file)
+{
+}
+
+static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
+			       sector_t *span)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+/*
+ * Update the number of bytes used in the VFS' inode. When we replace extents in
+ * a range (clone, dedupe, fallocate's zero range), we must update the number of
+ * bytes used by the inode in an atomic manner, so that concurrent stat(2) calls
+ * always get a correct value.
+ */
+void btrfs_update_inode_bytes(struct btrfs_inode *inode,
+			      const u64 add_bytes,
+			      const u64 del_bytes)
+{
+	if (add_bytes == del_bytes)
+		return;
+
+	spin_lock(&inode->lock);
+	if (del_bytes > 0)
+		inode_sub_bytes(&inode->vfs_inode, del_bytes);
+	if (add_bytes > 0)
+		inode_add_bytes(&inode->vfs_inode, add_bytes);
+	spin_unlock(&inode->lock);
+}
+
+/*
+ * Verify that there are no ordered extents for a given file range.
+ *
+ * @inode:   The target inode.
+ * @start:   Start offset of the file range, should be sector size aligned.
+ * @end:     End offset (inclusive) of the file range, its value +1 should be
+ *           sector size aligned.
+ *
+ * This should typically be used for cases where we locked an inode's VFS lock in
+ * exclusive mode, we have also locked the inode's i_mmap_lock in exclusive mode,
+ * we have flushed all delalloc in the range, we have waited for all ordered
+ * extents in the range to complete and finally we have locked the file range in
+ * the inode's io_tree.
+ */
+void btrfs_assert_inode_range_clean(struct btrfs_inode *inode, u64 start, u64 end)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_ordered_extent *ordered;
+
+	if (!IS_ENABLED(CONFIG_BTRFS_ASSERT))
+		return;
+
+	ordered = btrfs_lookup_first_ordered_range(inode, start, end + 1 - start);
+	if (ordered) {
+		btrfs_err(root->fs_info,
+"found unexpected ordered extent in file range [%llu, %llu] for inode %llu root %llu (ordered range [%llu, %llu])",
+			  start, end, btrfs_ino(inode), root->root_key.objectid,
+			  ordered->file_offset,
+			  ordered->file_offset + ordered->num_bytes - 1);
+		btrfs_put_ordered_extent(ordered);
+	}
+
+	ASSERT(ordered == NULL);
+}
+
+static const struct inode_operations btrfs_dir_inode_operations = {
+	.getattr	= btrfs_getattr,
+	.lookup		= btrfs_lookup,
+	.create		= btrfs_create,
+	.unlink		= btrfs_unlink,
+	.link		= btrfs_link,
+	.mkdir		= btrfs_mkdir,
+	.rmdir		= btrfs_rmdir,
+	.rename		= btrfs_rename2,
+	.symlink	= btrfs_symlink,
+	.setattr	= btrfs_setattr,
+	.mknod		= btrfs_mknod,
+	.listxattr	= btrfs_listxattr,
+	.permission	= btrfs_permission,
+	.get_inode_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+	.tmpfile        = btrfs_tmpfile,
+	.fileattr_get	= btrfs_fileattr_get,
+	.fileattr_set	= btrfs_fileattr_set,
+};
+
+static const struct file_operations btrfs_dir_file_operations = {
+	.llseek		= btrfs_dir_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= btrfs_real_readdir,
+	.open		= btrfs_opendir,
+	.unlocked_ioctl	= btrfs_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= btrfs_compat_ioctl,
+#endif
+	.release        = btrfs_release_file,
+	.fsync		= btrfs_sync_file,
+};
+
+/*
+ * btrfs doesn't support the bmap operation because swapfiles
+ * use bmap to make a mapping of extents in the file.  They assume
+ * these extents won't change over the life of the file and they
+ * use the bmap result to do IO directly to the drive.
+ *
+ * the btrfs bmap call would return logical addresses that aren't
+ * suitable for IO and they also will change frequently as COW
+ * operations happen.  So, swapfile + btrfs == corruption.
+ *
+ * For now we're avoiding this by dropping bmap.
+ */
+static const struct address_space_operations btrfs_aops = {
+	.read_folio	= btrfs_read_folio,
+	.writepages	= btrfs_writepages,
+	.readahead	= btrfs_readahead,
+	.invalidate_folio = btrfs_invalidate_folio,
+	.release_folio	= btrfs_release_folio,
+	.migrate_folio	= btrfs_migrate_folio,
+	.dirty_folio	= filemap_dirty_folio,
+	.error_remove_page = generic_error_remove_page,
+	.swap_activate	= btrfs_swap_activate,
+	.swap_deactivate = btrfs_swap_deactivate,
+};
+
+static const struct inode_operations btrfs_file_inode_operations = {
+	.getattr	= btrfs_getattr,
+	.setattr	= btrfs_setattr,
+	.listxattr      = btrfs_listxattr,
+	.permission	= btrfs_permission,
+	.fiemap		= btrfs_fiemap,
+	.get_inode_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+	.fileattr_get	= btrfs_fileattr_get,
+	.fileattr_set	= btrfs_fileattr_set,
+};
+static const struct inode_operations btrfs_special_inode_operations = {
+	.getattr	= btrfs_getattr,
+	.setattr	= btrfs_setattr,
+	.permission	= btrfs_permission,
+	.listxattr	= btrfs_listxattr,
+	.get_inode_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+};
+static const struct inode_operations btrfs_symlink_inode_operations = {
+	.get_link	= page_get_link,
+	.getattr	= btrfs_getattr,
+	.setattr	= btrfs_setattr,
+	.permission	= btrfs_permission,
+	.listxattr	= btrfs_listxattr,
+	.update_time	= btrfs_update_time,
+};
+
+const struct dentry_operations btrfs_dentry_operations = {
+	.d_delete	= btrfs_dentry_delete,
+};