Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 10802 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
new file mode 100644
index 000000000..f314b2c2d
--- /dev/null
+++ b/fs/btrfs/inode.c
@@ -0,0 +1,10802 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/buffer_head.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 <asm/unaligned.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 "volumes.h"
+#include "compression.h"
+#include "locking.h"
+#include "free-space-cache.h"
+#include "inode-map.h"
+#include "backref.h"
+#include "props.h"
+#include "qgroup.h"
+#include "dedupe.h"
+
+struct btrfs_iget_args {
+	struct btrfs_key *location;
+	struct btrfs_root *root;
+};
+
+struct btrfs_dio_data {
+	u64 reserve;
+	u64 unsubmitted_oe_range_start;
+	u64 unsubmitted_oe_range_end;
+	int overwrite;
+};
+
+static const struct inode_operations btrfs_dir_inode_operations;
+static const struct inode_operations btrfs_symlink_inode_operations;
+static const struct inode_operations btrfs_dir_ro_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 address_space_operations btrfs_symlink_aops;
+static const struct file_operations btrfs_dir_file_operations;
+static const struct extent_io_ops btrfs_extent_io_ops;
+
+static struct kmem_cache *btrfs_inode_cachep;
+struct kmem_cache *btrfs_trans_handle_cachep;
+struct kmem_cache *btrfs_path_cachep;
+struct kmem_cache *btrfs_free_space_cachep;
+struct kmem_cache *btrfs_free_space_bitmap_cachep;
+
+#define S_SHIFT 12
+static const unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = {
+	[S_IFREG >> S_SHIFT]	= BTRFS_FT_REG_FILE,
+	[S_IFDIR >> S_SHIFT]	= BTRFS_FT_DIR,
+	[S_IFCHR >> S_SHIFT]	= BTRFS_FT_CHRDEV,
+	[S_IFBLK >> S_SHIFT]	= BTRFS_FT_BLKDEV,
+	[S_IFIFO >> S_SHIFT]	= BTRFS_FT_FIFO,
+	[S_IFSOCK >> S_SHIFT]	= BTRFS_FT_SOCK,
+	[S_IFLNK >> S_SHIFT]	= BTRFS_FT_SYMLINK,
+};
+
+static int btrfs_setsize(struct inode *inode, struct iattr *attr);
+static int btrfs_truncate(struct inode *inode, bool skip_writeback);
+static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent);
+static noinline int cow_file_range(struct inode *inode,
+				   struct page *locked_page,
+				   u64 start, u64 end, u64 delalloc_end,
+				   int *page_started, unsigned long *nr_written,
+				   int unlock, struct btrfs_dedupe_hash *hash);
+static struct extent_map *create_io_em(struct 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 void __endio_write_update_ordered(struct inode *inode,
+					 const u64 offset, const u64 bytes,
+					 const bool uptodate);
+
+/*
+ * Cleanup all submitted ordered extents in specified range to handle errors
+ * from the fill_dellaloc() 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 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 = page_offset(locked_page);
+	u64 page_end = page_start + PAGE_SIZE - 1;
+
+	struct page *page;
+
+	while (index <= end_index) {
+		page = find_get_page(inode->i_mapping, index);
+		index++;
+		if (!page)
+			continue;
+		ClearPagePrivate2(page);
+		put_page(page);
+	}
+
+	/*
+	 * 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)) {
+		offset += PAGE_SIZE;
+		bytes -= PAGE_SIZE;
+	}
+
+	return __endio_write_update_ordered(inode, offset, bytes, false);
+}
+
+static int btrfs_dirty_inode(struct inode *inode);
+
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+void btrfs_test_inode_set_ops(struct inode *inode)
+{
+	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
+}
+#endif
+
+static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
+				     struct inode *inode,  struct inode *dir,
+				     const struct qstr *qstr)
+{
+	int err;
+
+	err = btrfs_init_acl(trans, inode, dir);
+	if (!err)
+		err = btrfs_xattr_security_init(trans, inode, dir, qstr);
+	return err;
+}
+
+/*
+ * 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, int extent_inserted,
+				struct btrfs_root *root, struct inode *inode,
+				u64 start, size_t size, size_t compressed_size,
+				int compress_type,
+				struct page **compressed_pages)
+{
+	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;
+	unsigned long offset;
+
+	if (compressed_size && compressed_pages)
+		cur_size = compressed_size;
+
+	inode_add_bytes(inode, size);
+
+	if (!extent_inserted) {
+		struct btrfs_key key;
+		size_t datasize;
+
+		key.objectid = btrfs_ino(BTRFS_I(inode));
+		key.offset = start;
+		key.type = BTRFS_EXTENT_DATA_KEY;
+
+		datasize = btrfs_file_extent_calc_inline_size(cur_size);
+		path->leave_spinning = 1;
+		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_atomic(cpage);
+			write_extent_buffer(leaf, kaddr, ptr, cur_size);
+			kunmap_atomic(kaddr);
+
+			i++;
+			ptr += cur_size;
+			compressed_size -= cur_size;
+		}
+		btrfs_set_file_extent_compression(leaf, ei,
+						  compress_type);
+	} else {
+		page = find_get_page(inode->i_mapping,
+				     start >> PAGE_SHIFT);
+		btrfs_set_file_extent_compression(leaf, ei, 0);
+		kaddr = kmap_atomic(page);
+		offset = start & (PAGE_SIZE - 1);
+		write_extent_buffer(leaf, kaddr + offset, ptr, size);
+		kunmap_atomic(kaddr);
+		put_page(page);
+	}
+	btrfs_mark_buffer_dirty(leaf);
+	btrfs_release_path(path);
+
+	/*
+	 * 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 isize and inode updates
+	 * before we unlock the pages.  Otherwise we
+	 * could end up racing with unlink.
+	 */
+	BTRFS_I(inode)->disk_i_size = inode->i_size;
+	ret = btrfs_update_inode(trans, root, inode);
+
+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 inode *inode, u64 start,
+					  u64 end, size_t compressed_size,
+					  int compress_type,
+					  struct page **compressed_pages)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	u64 isize = i_size_read(inode);
+	u64 actual_end = min(end + 1, isize);
+	u64 inline_len = actual_end - start;
+	u64 aligned_end = ALIGN(end, fs_info->sectorsize);
+	u64 data_len = inline_len;
+	int ret;
+	struct btrfs_path *path;
+	int extent_inserted = 0;
+	u32 extent_item_size;
+
+	if (compressed_size)
+		data_len = compressed_size;
+
+	if (start > 0 ||
+	    actual_end > fs_info->sectorsize ||
+	    data_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
+	    (!compressed_size &&
+	    (actual_end & (fs_info->sectorsize - 1)) == 0) ||
+	    end + 1 < isize ||
+	    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 = &BTRFS_I(inode)->block_rsv;
+
+	if (compressed_size && compressed_pages)
+		extent_item_size = btrfs_file_extent_calc_inline_size(
+		   compressed_size);
+	else
+		extent_item_size = btrfs_file_extent_calc_inline_size(
+		    inline_len);
+
+	ret = __btrfs_drop_extents(trans, root, inode, path,
+				   start, aligned_end, NULL,
+				   1, 1, extent_item_size, &extent_inserted);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	if (isize > actual_end)
+		inline_len = min_t(u64, isize, actual_end);
+	ret = insert_inline_extent(trans, path, extent_inserted,
+				   root, inode, start,
+				   inline_len, compressed_size,
+				   compress_type, compressed_pages);
+	if (ret && ret != -ENOSPC) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	} else if (ret == -ENOSPC) {
+		ret = 1;
+		goto out;
+	}
+
+	set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(inode)->runtime_flags);
+	btrfs_drop_extent_cache(BTRFS_I(inode), start, aligned_end - 1, 0);
+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);
+	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_cow {
+	struct inode *inode;
+	struct btrfs_root *root;
+	struct page *locked_page;
+	u64 start;
+	u64 end;
+	unsigned int write_flags;
+	struct list_head extents;
+	struct btrfs_work work;
+};
+
+static noinline int add_async_extent(struct async_cow *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 has flags compatible with compression
+ */
+static inline bool inode_can_compress(struct inode *inode)
+{
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW ||
+	    BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
+		return false;
+	return true;
+}
+
+/*
+ * 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 inode *inode, u64 start, u64 end)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+	if (!inode_can_compress(inode)) {
+		WARN(IS_ENABLED(CONFIG_BTRFS_DEBUG),
+			KERN_ERR "BTRFS: unexpected compression for ino %llu\n",
+			btrfs_ino(BTRFS_I(inode)));
+		return 0;
+	}
+	/* force compress */
+	if (btrfs_test_opt(fs_info, FORCE_COMPRESS))
+		return 1;
+	/* defrag ioctl */
+	if (BTRFS_I(inode)->defrag_compress)
+		return 1;
+	/* bad compression ratios */
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_NOCOMPRESS)
+		return 0;
+	if (btrfs_test_opt(fs_info, COMPRESS) ||
+	    BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS ||
+	    BTRFS_I(inode)->prop_compress)
+		return btrfs_compress_heuristic(inode, start, end);
+	return 0;
+}
+
+static inline void inode_should_defrag(struct btrfs_inode *inode,
+		u64 start, u64 end, u64 num_bytes, u64 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);
+}
+
+/*
+ * we create compressed extents in two phases.  The first
+ * phase compresses a range of pages that have already been
+ * locked (both pages and state bits are locked).
+ *
+ * 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 noinline void compress_file_range(struct inode *inode,
+					struct page *locked_page,
+					u64 start, u64 end,
+					struct async_cow *async_cow,
+					int *num_added)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	u64 blocksize = fs_info->sectorsize;
+	u64 actual_end;
+	u64 isize = i_size_read(inode);
+	int ret = 0;
+	struct page **pages = NULL;
+	unsigned long nr_pages;
+	unsigned long total_compressed = 0;
+	unsigned long total_in = 0;
+	int i;
+	int will_compress;
+	int compress_type = fs_info->compress_type;
+	int redirty = 0;
+
+	inode_should_defrag(BTRFS_I(inode), start, end, end - start + 1,
+			SZ_16K);
+
+	actual_end = min_t(u64, isize, end + 1);
+again:
+	will_compress = 0;
+	nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
+	BUILD_BUG_ON((BTRFS_MAX_COMPRESSED % PAGE_SIZE) != 0);
+	nr_pages = min_t(unsigned long, nr_pages,
+			BTRFS_MAX_COMPRESSED / PAGE_SIZE);
+
+	/*
+	 * 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 < BTRFS_I(inode)->disk_i_size))
+		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)) {
+		WARN_ON(pages);
+		pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
+		if (!pages) {
+			/* just bail out to the uncompressed code */
+			nr_pages = 0;
+			goto cont;
+		}
+
+		if (BTRFS_I(inode)->defrag_compress)
+			compress_type = BTRFS_I(inode)->defrag_compress;
+		else if (BTRFS_I(inode)->prop_compress)
+			compress_type = BTRFS_I(inode)->prop_compress;
+
+		/*
+		 * 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.
+		 *
+		 * If the compression fails for any reason, we set the pages
+		 * dirty again later on.
+		 *
+		 * Note that the remaining part is redirtied, the start pointer
+		 * has moved, the end is the original one.
+		 */
+		if (!redirty) {
+			extent_range_clear_dirty_for_io(inode, start, end);
+			redirty = 1;
+		}
+
+		/* Compression level is applied here and only here */
+		ret = btrfs_compress_pages(
+			compress_type | (fs_info->compress_level << 4),
+					   inode->i_mapping, start,
+					   pages,
+					   &nr_pages,
+					   &total_in,
+					   &total_compressed);
+
+		if (!ret) {
+			unsigned long offset = total_compressed &
+				(PAGE_SIZE - 1);
+			struct page *page = pages[nr_pages - 1];
+			char *kaddr;
+
+			/* zero the tail end of the last page, we might be
+			 * sending it down to disk
+			 */
+			if (offset) {
+				kaddr = kmap_atomic(page);
+				memset(kaddr + offset, 0,
+				       PAGE_SIZE - offset);
+				kunmap_atomic(kaddr);
+			}
+			will_compress = 1;
+		}
+	}
+cont:
+	if (start == 0) {
+		/* lets try to make an inline extent */
+		if (ret || total_in < actual_end) {
+			/* we didn't compress the entire range, try
+			 * to make an uncompressed inline extent.
+			 */
+			ret = cow_file_range_inline(inode, start, end, 0,
+						    BTRFS_COMPRESS_NONE, NULL);
+		} else {
+			/* try making a compressed inline extent */
+			ret = cow_file_range_inline(inode, start, end,
+						    total_compressed,
+						    compress_type, pages);
+		}
+		if (ret <= 0) {
+			unsigned long clear_flags = EXTENT_DELALLOC |
+				EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
+				EXTENT_DO_ACCOUNTING;
+			unsigned long page_error_op;
+
+			page_error_op = ret < 0 ? PAGE_SET_ERROR : 0;
+
+			/*
+			 * 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, end,
+						     NULL, clear_flags,
+						     PAGE_UNLOCK |
+						     PAGE_CLEAR_DIRTY |
+						     PAGE_SET_WRITEBACK |
+						     page_error_op |
+						     PAGE_END_WRITEBACK);
+
+			/*
+			 * Ensure we only free the compressed pages if we have
+			 * them allocated, as we can still reach here with
+			 * inode_need_compress() == false.
+			 */
+			if (pages) {
+				for (i = 0; i < nr_pages; i++) {
+					WARN_ON(pages[i]->mapping);
+					put_page(pages[i]);
+				}
+				kfree(pages);
+			}
+
+			return;
+		}
+	}
+
+	if (will_compress) {
+		/*
+		 * 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 size
+		 */
+		total_in = ALIGN(total_in, PAGE_SIZE);
+		if (total_compressed + blocksize <= total_in) {
+			*num_added += 1;
+
+			/*
+			 * The async work queues will take care of doing actual
+			 * allocation on disk for these compressed pages, and
+			 * will submit them to the elevator.
+			 */
+			add_async_extent(async_cow, start, total_in,
+					total_compressed, pages, nr_pages,
+					compress_type);
+
+			if (start + total_in < end) {
+				start += total_in;
+				pages = NULL;
+				cond_resched();
+				goto again;
+			}
+			return;
+		}
+	}
+	if (pages) {
+		/*
+		 * the compression code ran but failed to make things smaller,
+		 * free any pages it allocated and our page pointer array
+		 */
+		for (i = 0; i < nr_pages; i++) {
+			WARN_ON(pages[i]->mapping);
+			put_page(pages[i]);
+		}
+		kfree(pages);
+		pages = NULL;
+		total_compressed = 0;
+		nr_pages = 0;
+
+		/* flag the file so we don't compress in the future */
+		if (!btrfs_test_opt(fs_info, FORCE_COMPRESS) &&
+		    !(BTRFS_I(inode)->prop_compress)) {
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
+		}
+	}
+cleanup_and_bail_uncompressed:
+	/*
+	 * No compression, but we still need to write the pages in the file
+	 * we've been given so far.  redirty the locked page if it corresponds
+	 * to our extent and set things up for the async work queue to run
+	 * cow_file_range to do the normal delalloc dance.
+	 */
+	if (page_offset(locked_page) >= start &&
+	    page_offset(locked_page) <= end)
+		__set_page_dirty_nobuffers(locked_page);
+		/* unlocked later on in the async handlers */
+
+	if (redirty)
+		extent_range_redirty_for_io(inode, start, end);
+	add_async_extent(async_cow, start, end - start + 1, 0, NULL, 0,
+			 BTRFS_COMPRESS_NONE);
+	*num_added += 1;
+
+	return;
+}
+
+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;
+}
+
+/*
+ * 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 inode *inode,
+					      struct async_cow *async_cow)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct async_extent *async_extent;
+	u64 alloc_hint = 0;
+	struct btrfs_key ins;
+	struct extent_map *em;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct extent_io_tree *io_tree;
+	int ret = 0;
+
+again:
+	while (!list_empty(&async_cow->extents)) {
+		async_extent = list_entry(async_cow->extents.next,
+					  struct async_extent, list);
+		list_del(&async_extent->list);
+
+		io_tree = &BTRFS_I(inode)->io_tree;
+
+retry:
+		/* did the compression code fall back to uncompressed IO? */
+		if (!async_extent->pages) {
+			int page_started = 0;
+			unsigned long nr_written = 0;
+
+			lock_extent(io_tree, async_extent->start,
+					 async_extent->start +
+					 async_extent->ram_size - 1);
+
+			/* allocate blocks */
+			ret = cow_file_range(inode, async_cow->locked_page,
+					     async_extent->start,
+					     async_extent->start +
+					     async_extent->ram_size - 1,
+					     async_extent->start +
+					     async_extent->ram_size - 1,
+					     &page_started, &nr_written, 0,
+					     NULL);
+
+			/* JDM XXX */
+
+			/*
+			 * if page_started, cow_file_range inserted an
+			 * inline extent and took care of all the unlocking
+			 * and IO for us.  Otherwise, we need to submit
+			 * all those pages down to the drive.
+			 */
+			if (!page_started && !ret)
+				extent_write_locked_range(inode,
+						  async_extent->start,
+						  async_extent->start +
+						  async_extent->ram_size - 1,
+						  WB_SYNC_ALL);
+			else if (ret)
+				unlock_page(async_cow->locked_page);
+			kfree(async_extent);
+			cond_resched();
+			continue;
+		}
+
+		lock_extent(io_tree, async_extent->start,
+			    async_extent->start + async_extent->ram_size - 1);
+
+		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) {
+			free_async_extent_pages(async_extent);
+
+			if (ret == -ENOSPC) {
+				unlock_extent(io_tree, async_extent->start,
+					      async_extent->start +
+					      async_extent->ram_size - 1);
+
+				/*
+				 * we need to redirty the pages if we decide to
+				 * fallback to uncompressed IO, otherwise we
+				 * will not submit these pages down to lower
+				 * layers.
+				 */
+				extent_range_redirty_for_io(inode,
+						async_extent->start,
+						async_extent->start +
+						async_extent->ram_size - 1);
+
+				goto retry;
+			}
+			goto out_free;
+		}
+		/*
+		 * here we're doing allocation and writeback of the
+		 * compressed pages
+		 */
+		em = create_io_em(inode, async_extent->start,
+				  async_extent->ram_size, /* len */
+				  async_extent->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 value is not necessary due to void function */
+			goto out_free_reserve;
+		free_extent_map(em);
+
+		ret = btrfs_add_ordered_extent_compress(inode,
+						async_extent->start,
+						ins.objectid,
+						async_extent->ram_size,
+						ins.offset,
+						BTRFS_ORDERED_COMPRESSED,
+						async_extent->compress_type);
+		if (ret) {
+			btrfs_drop_extent_cache(BTRFS_I(inode),
+						async_extent->start,
+						async_extent->start +
+						async_extent->ram_size - 1, 0);
+			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, async_extent->start,
+				async_extent->start +
+				async_extent->ram_size - 1,
+				async_extent->start +
+				async_extent->ram_size - 1,
+				NULL, EXTENT_LOCKED | EXTENT_DELALLOC,
+				PAGE_UNLOCK | PAGE_CLEAR_DIRTY |
+				PAGE_SET_WRITEBACK);
+		if (btrfs_submit_compressed_write(inode,
+				    async_extent->start,
+				    async_extent->ram_size,
+				    ins.objectid,
+				    ins.offset, async_extent->pages,
+				    async_extent->nr_pages,
+				    async_cow->write_flags)) {
+			struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
+			struct page *p = async_extent->pages[0];
+			const u64 start = async_extent->start;
+			const u64 end = start + async_extent->ram_size - 1;
+
+			p->mapping = inode->i_mapping;
+			tree->ops->writepage_end_io_hook(p, start, end,
+							 NULL, 0);
+			p->mapping = NULL;
+			extent_clear_unlock_delalloc(inode, start, end, end,
+						     NULL, 0,
+						     PAGE_END_WRITEBACK |
+						     PAGE_SET_ERROR);
+			free_async_extent_pages(async_extent);
+		}
+		alloc_hint = ins.objectid + ins.offset;
+		kfree(async_extent);
+		cond_resched();
+	}
+	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:
+	extent_clear_unlock_delalloc(inode, async_extent->start,
+				     async_extent->start +
+				     async_extent->ram_size - 1,
+				     async_extent->start +
+				     async_extent->ram_size - 1,
+				     NULL, EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_DELALLOC_NEW |
+				     EXTENT_DEFRAG | EXTENT_DO_ACCOUNTING,
+				     PAGE_UNLOCK | PAGE_CLEAR_DIRTY |
+				     PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK |
+				     PAGE_SET_ERROR);
+	free_async_extent_pages(async_extent);
+	kfree(async_extent);
+	goto again;
+}
+
+static u64 get_extent_allocation_hint(struct inode *inode, u64 start,
+				      u64 num_bytes)
+{
+	struct extent_map_tree *em_tree = &BTRFS_I(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.
+ *
+ * *page_started is set to one if we unlock locked_page and do everything
+ * required to start IO on it.  It may be clean and already done with
+ * IO when we return.
+ */
+static noinline int cow_file_range(struct inode *inode,
+				   struct page *locked_page,
+				   u64 start, u64 end, u64 delalloc_end,
+				   int *page_started, unsigned long *nr_written,
+				   int unlock, struct btrfs_dedupe_hash *hash)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	u64 alloc_hint = 0;
+	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(BTRFS_I(inode))) {
+		WARN_ON_ONCE(1);
+		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(BTRFS_I(inode), start, end, num_bytes, SZ_64K);
+
+	if (start == 0) {
+		/* lets try to make an inline extent */
+		ret = cow_file_range_inline(inode, start, end, 0,
+					    BTRFS_COMPRESS_NONE, NULL);
+		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,
+				     delalloc_end, NULL,
+				     EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
+				     EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
+				     PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
+				     PAGE_END_WRITEBACK);
+			*nr_written = *nr_written +
+			     (end - start + PAGE_SIZE) / PAGE_SIZE;
+			*page_started = 1;
+			goto out;
+		} else if (ret < 0) {
+			goto out_unlock;
+		}
+	}
+
+	alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
+	btrfs_drop_extent_cache(BTRFS_I(inode), start,
+			start + num_bytes - 1, 0);
+
+	/*
+	 * 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 (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
+		min_alloc_size = num_bytes;
+	else
+		min_alloc_size = fs_info->sectorsize;
+
+	while (num_bytes > 0) {
+		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 < 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);
+
+		ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
+					       ram_size, cur_alloc_size, 0);
+		if (ret)
+			goto out_drop_extent_cache;
+
+		if (root->root_key.objectid ==
+		    BTRFS_DATA_RELOC_TREE_OBJECTID) {
+			ret = btrfs_reloc_clone_csums(inode, start,
+						      cur_alloc_size);
+			/*
+			 * 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_cache(BTRFS_I(inode), start,
+						start + ram_size - 1, 0);
+		}
+
+		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 Private2 bit so we know this page was properly
+		 * setup for writepage
+		 */
+		page_ops = unlock ? PAGE_UNLOCK : 0;
+		page_ops |= PAGE_SET_PRIVATE2;
+
+		extent_clear_unlock_delalloc(inode, start,
+					     start + ram_size - 1,
+					     delalloc_end, 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;
+	}
+out:
+	return ret;
+
+out_drop_extent_cache:
+	btrfs_drop_extent_cache(BTRFS_I(inode), start, start + ram_size - 1, 0);
+out_reserve:
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
+out_unlock:
+	clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+		EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV;
+	page_ops = PAGE_UNLOCK | PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
+		PAGE_END_WRITEBACK;
+	/*
+	 * 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,
+					     start + cur_alloc_size - 1,
+					     locked_page,
+					     clear_bits,
+					     page_ops);
+		start += cur_alloc_size;
+		if (start >= end)
+			goto out;
+	}
+	extent_clear_unlock_delalloc(inode, start, end, delalloc_end,
+				     locked_page,
+				     clear_bits | EXTENT_CLEAR_DATA_RESV,
+				     page_ops);
+	goto out;
+}
+
+/*
+ * work queue call back to started compression on a file and pages
+ */
+static noinline void async_cow_start(struct btrfs_work *work)
+{
+	struct async_cow *async_cow;
+	int num_added = 0;
+	async_cow = container_of(work, struct async_cow, work);
+
+	compress_file_range(async_cow->inode, async_cow->locked_page,
+			    async_cow->start, async_cow->end, async_cow,
+			    &num_added);
+	if (num_added == 0) {
+		btrfs_add_delayed_iput(async_cow->inode);
+		async_cow->inode = NULL;
+	}
+}
+
+/*
+ * work queue call back to submit previously compressed pages
+ */
+static noinline void async_cow_submit(struct btrfs_work *work)
+{
+	struct btrfs_fs_info *fs_info;
+	struct async_cow *async_cow;
+	struct btrfs_root *root;
+	unsigned long nr_pages;
+
+	async_cow = container_of(work, struct async_cow, work);
+
+	root = async_cow->root;
+	fs_info = root->fs_info;
+	nr_pages = (async_cow->end - async_cow->start + PAGE_SIZE) >>
+		PAGE_SHIFT;
+
+	/* 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);
+
+	if (async_cow->inode)
+		submit_compressed_extents(async_cow->inode, async_cow);
+}
+
+static noinline void async_cow_free(struct btrfs_work *work)
+{
+	struct async_cow *async_cow;
+	async_cow = container_of(work, struct async_cow, work);
+	if (async_cow->inode)
+		btrfs_add_delayed_iput(async_cow->inode);
+	kfree(async_cow);
+}
+
+static int cow_file_range_async(struct inode *inode, struct page *locked_page,
+				u64 start, u64 end, int *page_started,
+				unsigned long *nr_written,
+				unsigned int write_flags)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct async_cow *async_cow;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	unsigned long nr_pages;
+	u64 cur_end;
+
+	clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, EXTENT_LOCKED,
+			 1, 0, NULL);
+	while (start < end) {
+		async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);
+		BUG_ON(!async_cow); /* -ENOMEM */
+		async_cow->inode = igrab(inode);
+		async_cow->root = root;
+		async_cow->locked_page = locked_page;
+		async_cow->start = start;
+		async_cow->write_flags = write_flags;
+
+		if (BTRFS_I(inode)->flags & BTRFS_INODE_NOCOMPRESS &&
+		    !btrfs_test_opt(fs_info, FORCE_COMPRESS))
+			cur_end = end;
+		else
+			cur_end = min(end, start + SZ_512K - 1);
+
+		async_cow->end = cur_end;
+		INIT_LIST_HEAD(&async_cow->extents);
+
+		btrfs_init_work(&async_cow->work,
+				btrfs_delalloc_helper,
+				async_cow_start, async_cow_submit,
+				async_cow_free);
+
+		nr_pages = (cur_end - start + PAGE_SIZE) >>
+			PAGE_SHIFT;
+		atomic_add(nr_pages, &fs_info->async_delalloc_pages);
+
+		btrfs_queue_work(fs_info->delalloc_workers, &async_cow->work);
+
+		*nr_written += nr_pages;
+		start = cur_end + 1;
+	}
+	*page_started = 1;
+	return 0;
+}
+
+static noinline int csum_exist_in_range(struct btrfs_fs_info *fs_info,
+					u64 bytenr, u64 num_bytes)
+{
+	int ret;
+	struct btrfs_ordered_sum *sums;
+	LIST_HEAD(list);
+
+	ret = btrfs_lookup_csums_range(fs_info->csum_root, bytenr,
+				       bytenr + num_bytes - 1, &list, 0);
+	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;
+}
+
+/*
+ * 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 inode *inode,
+				       struct page *locked_page,
+			      u64 start, u64 end, int *page_started, int force,
+			      unsigned long *nr_written)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct extent_buffer *leaf;
+	struct btrfs_path *path;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_key found_key;
+	struct extent_map *em;
+	u64 cow_start;
+	u64 cur_offset;
+	u64 extent_end;
+	u64 extent_offset;
+	u64 disk_bytenr;
+	u64 num_bytes;
+	u64 disk_num_bytes;
+	u64 ram_bytes;
+	int extent_type;
+	int ret;
+	int type;
+	int nocow;
+	int check_prev = 1;
+	bool nolock;
+	u64 ino = btrfs_ino(BTRFS_I(inode));
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		extent_clear_unlock_delalloc(inode, start, end, end,
+					     locked_page,
+					     EXTENT_LOCKED | EXTENT_DELALLOC |
+					     EXTENT_DO_ACCOUNTING |
+					     EXTENT_DEFRAG, PAGE_UNLOCK |
+					     PAGE_CLEAR_DIRTY |
+					     PAGE_SET_WRITEBACK |
+					     PAGE_END_WRITEBACK);
+		return -ENOMEM;
+	}
+
+	nolock = btrfs_is_free_space_inode(BTRFS_I(inode));
+
+	cow_start = (u64)-1;
+	cur_offset = start;
+	while (1) {
+		ret = btrfs_lookup_file_extent(NULL, root, path, ino,
+					       cur_offset, 0);
+		if (ret < 0)
+			goto error;
+		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 = 0;
+next_slot:
+		leaf = path->nodes[0];
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0) {
+				if (cow_start != (u64)-1)
+					cur_offset = cow_start;
+				goto error;
+			}
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+		}
+
+		nocow = 0;
+		disk_bytenr = 0;
+		num_bytes = 0;
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		if (found_key.objectid > ino)
+			break;
+		if (WARN_ON_ONCE(found_key.objectid < ino) ||
+		    found_key.type < BTRFS_EXTENT_DATA_KEY) {
+			path->slots[0]++;
+			goto next_slot;
+		}
+		if (found_key.type > BTRFS_EXTENT_DATA_KEY ||
+		    found_key.offset > end)
+			break;
+
+		if (found_key.offset > cur_offset) {
+			extent_end = found_key.offset;
+			extent_type = 0;
+			goto out_check;
+		}
+
+		fi = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_file_extent_item);
+		extent_type = btrfs_file_extent_type(leaf, fi);
+
+		ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
+		if (extent_type == BTRFS_FILE_EXTENT_REG ||
+		    extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+			disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+			extent_offset = btrfs_file_extent_offset(leaf, fi);
+			extent_end = found_key.offset +
+				btrfs_file_extent_num_bytes(leaf, fi);
+			disk_num_bytes =
+				btrfs_file_extent_disk_num_bytes(leaf, fi);
+			if (extent_end <= start) {
+				path->slots[0]++;
+				goto next_slot;
+			}
+			if (disk_bytenr == 0)
+				goto out_check;
+			if (btrfs_file_extent_compression(leaf, fi) ||
+			    btrfs_file_extent_encryption(leaf, fi) ||
+			    btrfs_file_extent_other_encoding(leaf, fi))
+				goto out_check;
+			/*
+			 * Do the same check as in btrfs_cross_ref_exist but
+			 * without the unnecessary search.
+			 */
+			if (!nolock &&
+			    btrfs_file_extent_generation(leaf, fi) <=
+			    btrfs_root_last_snapshot(&root->root_item))
+				goto out_check;
+			if (extent_type == BTRFS_FILE_EXTENT_REG && !force)
+				goto out_check;
+			if (btrfs_extent_readonly(fs_info, disk_bytenr))
+				goto out_check;
+			ret = btrfs_cross_ref_exist(root, ino,
+						    found_key.offset -
+						    extent_offset, disk_bytenr);
+			if (ret) {
+				/*
+				 * ret could be -EIO if the above fails to read
+				 * metadata.
+				 */
+				if (ret < 0) {
+					if (cow_start != (u64)-1)
+						cur_offset = cow_start;
+					goto error;
+				}
+
+				WARN_ON_ONCE(nolock);
+				goto out_check;
+			}
+			disk_bytenr += extent_offset;
+			disk_bytenr += cur_offset - found_key.offset;
+			num_bytes = min(end + 1, extent_end) - cur_offset;
+			/*
+			 * if there are pending snapshots for this root,
+			 * we fall into common COW way.
+			 */
+			if (!nolock && atomic_read(&root->snapshot_force_cow))
+				goto out_check;
+			/*
+			 * force cow if csum exists in the range.
+			 * this ensure that csum for a given extent are
+			 * either valid or do not exist.
+			 */
+			ret = csum_exist_in_range(fs_info, disk_bytenr,
+						  num_bytes);
+			if (ret) {
+				/*
+				 * ret could be -EIO if the above fails to read
+				 * metadata.
+				 */
+				if (ret < 0) {
+					if (cow_start != (u64)-1)
+						cur_offset = cow_start;
+					goto error;
+				}
+				WARN_ON_ONCE(nolock);
+				goto out_check;
+			}
+			if (!btrfs_inc_nocow_writers(fs_info, disk_bytenr))
+				goto out_check;
+			nocow = 1;
+		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+			extent_end = found_key.offset +
+				btrfs_file_extent_ram_bytes(leaf, fi);
+			extent_end = ALIGN(extent_end,
+					   fs_info->sectorsize);
+		} else {
+			BUG_ON(1);
+		}
+out_check:
+		if (extent_end <= start) {
+			path->slots[0]++;
+			if (nocow)
+				btrfs_dec_nocow_writers(fs_info, disk_bytenr);
+			goto next_slot;
+		}
+		if (!nocow) {
+			if (cow_start == (u64)-1)
+				cow_start = cur_offset;
+			cur_offset = extent_end;
+			if (cur_offset > end)
+				break;
+			path->slots[0]++;
+			goto next_slot;
+		}
+
+		btrfs_release_path(path);
+		if (cow_start != (u64)-1) {
+			ret = cow_file_range(inode, locked_page,
+					     cow_start, found_key.offset - 1,
+					     end, page_started, nr_written, 1,
+					     NULL);
+			if (ret) {
+				if (nocow)
+					btrfs_dec_nocow_writers(fs_info,
+								disk_bytenr);
+				goto error;
+			}
+			cow_start = (u64)-1;
+		}
+
+		if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+			u64 orig_start = found_key.offset - extent_offset;
+
+			em = create_io_em(inode, cur_offset, num_bytes,
+					  orig_start,
+					  disk_bytenr, /* block_start */
+					  num_bytes, /* block_len */
+					  disk_num_bytes, /* orig_block_len */
+					  ram_bytes, BTRFS_COMPRESS_NONE,
+					  BTRFS_ORDERED_PREALLOC);
+			if (IS_ERR(em)) {
+				if (nocow)
+					btrfs_dec_nocow_writers(fs_info,
+								disk_bytenr);
+				ret = PTR_ERR(em);
+				goto error;
+			}
+			free_extent_map(em);
+		}
+
+		if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+			type = BTRFS_ORDERED_PREALLOC;
+		} else {
+			type = BTRFS_ORDERED_NOCOW;
+		}
+
+		ret = btrfs_add_ordered_extent(inode, cur_offset, disk_bytenr,
+					       num_bytes, num_bytes, type);
+		if (nocow)
+			btrfs_dec_nocow_writers(fs_info, disk_bytenr);
+		BUG_ON(ret); /* -ENOMEM */
+
+		if (root->root_key.objectid ==
+		    BTRFS_DATA_RELOC_TREE_OBJECTID)
+			/*
+			 * 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(inode, cur_offset,
+						      num_bytes);
+
+		extent_clear_unlock_delalloc(inode, cur_offset,
+					     cur_offset + num_bytes - 1, end,
+					     locked_page, EXTENT_LOCKED |
+					     EXTENT_DELALLOC |
+					     EXTENT_CLEAR_DATA_RESV,
+					     PAGE_UNLOCK | PAGE_SET_PRIVATE2);
+
+		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 = cow_file_range(inode, locked_page, cow_start, end, end,
+				     page_started, nr_written, 1, NULL);
+		if (ret)
+			goto error;
+	}
+
+error:
+	if (ret && cur_offset < end)
+		extent_clear_unlock_delalloc(inode, cur_offset, end, end,
+					     locked_page, EXTENT_LOCKED |
+					     EXTENT_DELALLOC | EXTENT_DEFRAG |
+					     EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
+					     PAGE_CLEAR_DIRTY |
+					     PAGE_SET_WRITEBACK |
+					     PAGE_END_WRITEBACK);
+	btrfs_free_path(path);
+	return ret;
+}
+
+static inline int need_force_cow(struct inode *inode, u64 start, u64 end)
+{
+
+	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
+	    !(BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC))
+		return 0;
+
+	/*
+	 * @defrag_bytes is a hint value, no spinlock held here,
+	 * if is not zero, it means the file is defragging.
+	 * Force cow if given extent needs to be defragged.
+	 */
+	if (BTRFS_I(inode)->defrag_bytes &&
+	    test_range_bit(&BTRFS_I(inode)->io_tree, start, end,
+			   EXTENT_DEFRAG, 0, NULL))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Function to process delayed allocation (create CoW) for ranges which are
+ * being touched for the first time.
+ */
+int btrfs_run_delalloc_range(void *private_data, struct page *locked_page,
+		u64 start, u64 end, int *page_started, unsigned long *nr_written,
+		struct writeback_control *wbc)
+{
+	struct inode *inode = private_data;
+	int ret;
+	int force_cow = need_force_cow(inode, start, end);
+	unsigned int write_flags = wbc_to_write_flags(wbc);
+
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW && !force_cow) {
+		ret = run_delalloc_nocow(inode, locked_page, start, end,
+					 page_started, 1, nr_written);
+	} else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC && !force_cow) {
+		ret = run_delalloc_nocow(inode, locked_page, start, end,
+					 page_started, 0, nr_written);
+	} else if (!inode_can_compress(inode) ||
+		   !inode_need_compress(inode, start, end)) {
+		ret = cow_file_range(inode, locked_page, start, end, end,
+				      page_started, nr_written, 1, NULL);
+	} else {
+		set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+			&BTRFS_I(inode)->runtime_flags);
+		ret = cow_file_range_async(inode, locked_page, start, end,
+					   page_started, nr_written,
+					   write_flags);
+	}
+	if (ret)
+		btrfs_cleanup_ordered_extents(inode, locked_page, start,
+					      end - start + 1);
+	return ret;
+}
+
+static void btrfs_split_extent_hook(void *private_data,
+				    struct extent_state *orig, u64 split)
+{
+	struct inode *inode = private_data;
+	u64 size;
+
+	/* not delalloc, ignore it */
+	if (!(orig->state & EXTENT_DELALLOC))
+		return;
+
+	size = orig->end - orig->start + 1;
+	if (size > BTRFS_MAX_EXTENT_SIZE) {
+		u32 num_extents;
+		u64 new_size;
+
+		/*
+		 * See the explanation in btrfs_merge_extent_hook, the same
+		 * applies here, just in reverse.
+		 */
+		new_size = orig->end - split + 1;
+		num_extents = count_max_extents(new_size);
+		new_size = split - orig->start;
+		num_extents += count_max_extents(new_size);
+		if (count_max_extents(size) >= num_extents)
+			return;
+	}
+
+	spin_lock(&BTRFS_I(inode)->lock);
+	btrfs_mod_outstanding_extents(BTRFS_I(inode), 1);
+	spin_unlock(&BTRFS_I(inode)->lock);
+}
+
+/*
+ * extent_io.c merge_extent_hook, used to track 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.
+ */
+static void btrfs_merge_extent_hook(void *private_data,
+				    struct extent_state *new,
+				    struct extent_state *other)
+{
+	struct inode *inode = private_data;
+	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 <= BTRFS_MAX_EXTENT_SIZE) {
+		spin_lock(&BTRFS_I(inode)->lock);
+		btrfs_mod_outstanding_extents(BTRFS_I(inode), -1);
+		spin_unlock(&BTRFS_I(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(old_size);
+	old_size = new->end - new->start + 1;
+	num_extents += count_max_extents(old_size);
+	if (count_max_extents(new_size) >= num_extents)
+		return;
+
+	spin_lock(&BTRFS_I(inode)->lock);
+	btrfs_mod_outstanding_extents(BTRFS_I(inode), -1);
+	spin_unlock(&BTRFS_I(inode)->lock);
+}
+
+static void btrfs_add_delalloc_inodes(struct btrfs_root *root,
+				      struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+	spin_lock(&root->delalloc_lock);
+	if (list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
+		list_add_tail(&BTRFS_I(inode)->delalloc_inodes,
+			      &root->delalloc_inodes);
+		set_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+			&BTRFS_I(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);
+}
+
+/*
+ * extent_io.c set_bit_hook, used to track delayed allocation
+ * bytes in this file, and to maintain the list of inodes that
+ * have pending delalloc work to be done.
+ */
+static void btrfs_set_bit_hook(void *private_data,
+			       struct extent_state *state, unsigned *bits)
+{
+	struct inode *inode = private_data;
+
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+	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 = BTRFS_I(inode)->root;
+		u64 len = state->end + 1 - state->start;
+		u32 num_extents = count_max_extents(len);
+		bool do_list = !btrfs_is_free_space_inode(BTRFS_I(inode));
+
+		spin_lock(&BTRFS_I(inode)->lock);
+		btrfs_mod_outstanding_extents(BTRFS_I(inode), num_extents);
+		spin_unlock(&BTRFS_I(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(&BTRFS_I(inode)->lock);
+		BTRFS_I(inode)->delalloc_bytes += len;
+		if (*bits & EXTENT_DEFRAG)
+			BTRFS_I(inode)->defrag_bytes += len;
+		if (do_list && !test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+					 &BTRFS_I(inode)->runtime_flags))
+			btrfs_add_delalloc_inodes(root, inode);
+		spin_unlock(&BTRFS_I(inode)->lock);
+	}
+
+	if (!(state->state & EXTENT_DELALLOC_NEW) &&
+	    (*bits & EXTENT_DELALLOC_NEW)) {
+		spin_lock(&BTRFS_I(inode)->lock);
+		BTRFS_I(inode)->new_delalloc_bytes += state->end + 1 -
+			state->start;
+		spin_unlock(&BTRFS_I(inode)->lock);
+	}
+}
+
+/*
+ * extent_io.c clear_bit_hook, see set_bit_hook for why
+ */
+static void btrfs_clear_bit_hook(void *private_data,
+				 struct extent_state *state,
+				 unsigned *bits)
+{
+	struct btrfs_inode *inode = BTRFS_I((struct inode *)private_data);
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->vfs_inode.i_sb);
+	u64 len = state->end + 1 - state->start;
+	u32 num_extents = count_max_extents(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 dellalloc_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 (root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID &&
+		    do_list && !(state->state & EXTENT_NORESERVE) &&
+		    (*bits & EXTENT_CLEAR_DATA_RESV))
+			btrfs_free_reserved_data_space_noquota(
+					&inode->vfs_inode,
+					state->start, 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;
+		spin_unlock(&inode->lock);
+	}
+}
+
+/*
+ * Merge bio hook, this must check the chunk tree to make sure we don't create
+ * bios that span stripes or chunks
+ *
+ * return 1 if page cannot be merged to bio
+ * return 0 if page can be merged to bio
+ * return error otherwise
+ */
+int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
+			 size_t size, struct bio *bio,
+			 unsigned long bio_flags)
+{
+	struct inode *inode = page->mapping->host;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	u64 logical = (u64)bio->bi_iter.bi_sector << 9;
+	u64 length = 0;
+	u64 map_length;
+	int ret;
+
+	if (bio_flags & EXTENT_BIO_COMPRESSED)
+		return 0;
+
+	length = bio->bi_iter.bi_size;
+	map_length = length;
+	ret = btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,
+			      NULL, 0);
+	if (ret < 0)
+		return ret;
+	if (map_length < length + size)
+		return 1;
+	return 0;
+}
+
+/*
+ * in order to insert checksums into the metadata in large chunks,
+ * we wait until bio submission time.   All the pages in the bio are
+ * checksummed and sums are attached onto the ordered extent record.
+ *
+ * At IO completion time the cums attached on the ordered extent record
+ * are inserted into the btree
+ */
+static blk_status_t btrfs_submit_bio_start(void *private_data, struct bio *bio,
+				    u64 bio_offset)
+{
+	struct inode *inode = private_data;
+	blk_status_t ret = 0;
+
+	ret = btrfs_csum_one_bio(inode, bio, 0, 0);
+	BUG_ON(ret); /* -ENOMEM */
+	return 0;
+}
+
+/*
+ * in order to insert checksums into the metadata in large chunks,
+ * we wait until bio submission time.   All the pages in the bio are
+ * checksummed and sums are attached onto the ordered extent record.
+ *
+ * At IO completion time the cums attached on the ordered extent record
+ * are inserted into the btree
+ */
+blk_status_t btrfs_submit_bio_done(void *private_data, struct bio *bio,
+			  int mirror_num)
+{
+	struct inode *inode = private_data;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	blk_status_t ret;
+
+	ret = btrfs_map_bio(fs_info, bio, mirror_num, 1);
+	if (ret) {
+		bio->bi_status = ret;
+		bio_endio(bio);
+	}
+	return ret;
+}
+
+/*
+ * extent_io.c submission hook. This does the right thing for csum calculation
+ * on write, or reading the csums from the tree before a read.
+ *
+ * Rules about async/sync submit,
+ * a) read:				sync submit
+ *
+ * b) write without checksum:		sync submit
+ *
+ * c) write with checksum:
+ *    c-1) if bio is issued by fsync:	sync submit
+ *         (sync_writers != 0)
+ *
+ *    c-2) if root is reloc root:	sync submit
+ *         (only in case of buffered IO)
+ *
+ *    c-3) otherwise:			async submit
+ */
+static blk_status_t btrfs_submit_bio_hook(void *private_data, struct bio *bio,
+				 int mirror_num, unsigned long bio_flags,
+				 u64 bio_offset)
+{
+	struct inode *inode = private_data;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	enum btrfs_wq_endio_type metadata = BTRFS_WQ_ENDIO_DATA;
+	blk_status_t ret = 0;
+	int skip_sum;
+	int async = !atomic_read(&BTRFS_I(inode)->sync_writers);
+
+	skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
+
+	if (btrfs_is_free_space_inode(BTRFS_I(inode)))
+		metadata = BTRFS_WQ_ENDIO_FREE_SPACE;
+
+	if (bio_op(bio) != REQ_OP_WRITE) {
+		ret = btrfs_bio_wq_end_io(fs_info, bio, metadata);
+		if (ret)
+			goto out;
+
+		if (bio_flags & EXTENT_BIO_COMPRESSED) {
+			ret = btrfs_submit_compressed_read(inode, bio,
+							   mirror_num,
+							   bio_flags);
+			goto out;
+		} else if (!skip_sum) {
+			ret = btrfs_lookup_bio_sums(inode, bio, NULL);
+			if (ret)
+				goto out;
+		}
+		goto mapit;
+	} else if (async && !skip_sum) {
+		/* csum items have already been cloned */
+		if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
+			goto mapit;
+		/* we're doing a write, do the async checksumming */
+		ret = btrfs_wq_submit_bio(fs_info, bio, mirror_num, bio_flags,
+					  bio_offset, inode,
+					  btrfs_submit_bio_start);
+		goto out;
+	} else if (!skip_sum) {
+		ret = btrfs_csum_one_bio(inode, bio, 0, 0);
+		if (ret)
+			goto out;
+	}
+
+mapit:
+	ret = btrfs_map_bio(fs_info, bio, mirror_num, 0);
+
+out:
+	if (ret) {
+		bio->bi_status = ret;
+		bio_endio(bio);
+	}
+	return ret;
+}
+
+/*
+ * 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 noinline int add_pending_csums(struct btrfs_trans_handle *trans,
+			     struct inode *inode, struct list_head *list)
+{
+	struct btrfs_ordered_sum *sum;
+	int ret;
+
+	list_for_each_entry(sum, list, list) {
+		trans->adding_csums = true;
+		ret = btrfs_csum_file_blocks(trans,
+		       BTRFS_I(inode)->root->fs_info->csum_root, sum);
+		trans->adding_csums = false;
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end,
+			      unsigned int extra_bits,
+			      struct extent_state **cached_state, int dedupe)
+{
+	WARN_ON((end & (PAGE_SIZE - 1)) == 0);
+	return set_extent_delalloc(&BTRFS_I(inode)->io_tree, start, end,
+				   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_work work;
+};
+
+static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
+{
+	struct btrfs_writepage_fixup *fixup;
+	struct btrfs_ordered_extent *ordered;
+	struct extent_state *cached_state = NULL;
+	struct extent_changeset *data_reserved = NULL;
+	struct page *page;
+	struct inode *inode;
+	u64 page_start;
+	u64 page_end;
+	int ret;
+
+	fixup = container_of(work, struct btrfs_writepage_fixup, work);
+	page = fixup->page;
+again:
+	lock_page(page);
+	if (!page->mapping || !PageDirty(page) || !PageChecked(page)) {
+		ClearPageChecked(page);
+		goto out_page;
+	}
+
+	inode = page->mapping->host;
+	page_start = page_offset(page);
+	page_end = page_offset(page) + PAGE_SIZE - 1;
+
+	lock_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end,
+			 &cached_state);
+
+	/* already ordered? We're done */
+	if (PagePrivate2(page))
+		goto out;
+
+	ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start,
+					PAGE_SIZE);
+	if (ordered) {
+		unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start,
+				     page_end, &cached_state);
+		unlock_page(page);
+		btrfs_start_ordered_extent(inode, ordered, 1);
+		btrfs_put_ordered_extent(ordered);
+		goto again;
+	}
+
+	ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
+					   PAGE_SIZE);
+	if (ret) {
+		mapping_set_error(page->mapping, ret);
+		end_extent_writepage(page, ret, page_start, page_end);
+		ClearPageChecked(page);
+		goto out;
+	 }
+
+	ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
+					&cached_state, 0);
+	if (ret) {
+		mapping_set_error(page->mapping, ret);
+		end_extent_writepage(page, ret, page_start, page_end);
+		ClearPageChecked(page);
+		goto out_reserved;
+	}
+
+	ClearPageChecked(page);
+	set_page_dirty(page);
+out_reserved:
+	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
+	if (ret)
+		btrfs_delalloc_release_space(inode, data_reserved, page_start,
+					     PAGE_SIZE, true);
+out:
+	unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start, page_end,
+			     &cached_state);
+out_page:
+	unlock_page(page);
+	put_page(page);
+	kfree(fixup);
+	extent_changeset_free(data_reserved);
+}
+
+/*
+ * 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.
+ */
+static int btrfs_writepage_start_hook(struct page *page, u64 start, u64 end)
+{
+	struct inode *inode = page->mapping->host;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_writepage_fixup *fixup;
+
+	/* this page is properly in the ordered list */
+	if (TestClearPagePrivate2(page))
+		return 0;
+
+	if (PageChecked(page))
+		return -EAGAIN;
+
+	fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
+	if (!fixup)
+		return -EAGAIN;
+
+	SetPageChecked(page);
+	get_page(page);
+	btrfs_init_work(&fixup->work, btrfs_fixup_helper,
+			btrfs_writepage_fixup_worker, NULL, NULL);
+	fixup->page = page;
+	btrfs_queue_work(fs_info->fixup_workers, &fixup->work);
+	return -EBUSY;
+}
+
+static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
+				       struct inode *inode, u64 file_pos,
+				       u64 disk_bytenr, u64 disk_num_bytes,
+				       u64 num_bytes, u64 ram_bytes,
+				       u8 compression, u8 encryption,
+				       u16 other_encoding, int extent_type)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_key ins;
+	u64 qg_released;
+	int extent_inserted = 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.
+	 */
+	ret = __btrfs_drop_extents(trans, root, inode, path, file_pos,
+				   file_pos + num_bytes, NULL, 0,
+				   1, sizeof(*fi), &extent_inserted);
+	if (ret)
+		goto out;
+
+	if (!extent_inserted) {
+		ins.objectid = btrfs_ino(BTRFS_I(inode));
+		ins.offset = file_pos;
+		ins.type = BTRFS_EXTENT_DATA_KEY;
+
+		path->leave_spinning = 1;
+		ret = btrfs_insert_empty_item(trans, root, path, &ins,
+					      sizeof(*fi));
+		if (ret)
+			goto out;
+	}
+	leaf = path->nodes[0];
+	fi = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, fi, trans->transid);
+	btrfs_set_file_extent_type(leaf, fi, extent_type);
+	btrfs_set_file_extent_disk_bytenr(leaf, fi, disk_bytenr);
+	btrfs_set_file_extent_disk_num_bytes(leaf, fi, disk_num_bytes);
+	btrfs_set_file_extent_offset(leaf, fi, 0);
+	btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
+	btrfs_set_file_extent_ram_bytes(leaf, fi, ram_bytes);
+	btrfs_set_file_extent_compression(leaf, fi, compression);
+	btrfs_set_file_extent_encryption(leaf, fi, encryption);
+	btrfs_set_file_extent_other_encoding(leaf, fi, other_encoding);
+
+	btrfs_mark_buffer_dirty(leaf);
+	btrfs_release_path(path);
+
+	inode_add_bytes(inode, num_bytes);
+
+	ins.objectid = disk_bytenr;
+	ins.offset = disk_num_bytes;
+	ins.type = BTRFS_EXTENT_ITEM_KEY;
+
+	/*
+	 * Release the reserved range from inode dirty range map, as it is
+	 * already moved into delayed_ref_head
+	 */
+	ret = btrfs_qgroup_release_data(inode, file_pos, ram_bytes);
+	if (ret < 0)
+		goto out;
+	qg_released = ret;
+	ret = btrfs_alloc_reserved_file_extent(trans, root,
+					       btrfs_ino(BTRFS_I(inode)),
+					       file_pos, qg_released, &ins);
+out:
+	btrfs_free_path(path);
+
+	return ret;
+}
+
+/* snapshot-aware defrag */
+struct sa_defrag_extent_backref {
+	struct rb_node node;
+	struct old_sa_defrag_extent *old;
+	u64 root_id;
+	u64 inum;
+	u64 file_pos;
+	u64 extent_offset;
+	u64 num_bytes;
+	u64 generation;
+};
+
+struct old_sa_defrag_extent {
+	struct list_head list;
+	struct new_sa_defrag_extent *new;
+
+	u64 extent_offset;
+	u64 bytenr;
+	u64 offset;
+	u64 len;
+	int count;
+};
+
+struct new_sa_defrag_extent {
+	struct rb_root root;
+	struct list_head head;
+	struct btrfs_path *path;
+	struct inode *inode;
+	u64 file_pos;
+	u64 len;
+	u64 bytenr;
+	u64 disk_len;
+	u8 compress_type;
+};
+
+static int backref_comp(struct sa_defrag_extent_backref *b1,
+			struct sa_defrag_extent_backref *b2)
+{
+	if (b1->root_id < b2->root_id)
+		return -1;
+	else if (b1->root_id > b2->root_id)
+		return 1;
+
+	if (b1->inum < b2->inum)
+		return -1;
+	else if (b1->inum > b2->inum)
+		return 1;
+
+	if (b1->file_pos < b2->file_pos)
+		return -1;
+	else if (b1->file_pos > b2->file_pos)
+		return 1;
+
+	/*
+	 * [------------------------------] ===> (a range of space)
+	 *     |<--->|   |<---->| =============> (fs/file tree A)
+	 * |<---------------------------->| ===> (fs/file tree B)
+	 *
+	 * A range of space can refer to two file extents in one tree while
+	 * refer to only one file extent in another tree.
+	 *
+	 * So we may process a disk offset more than one time(two extents in A)
+	 * and locate at the same extent(one extent in B), then insert two same
+	 * backrefs(both refer to the extent in B).
+	 */
+	return 0;
+}
+
+static void backref_insert(struct rb_root *root,
+			   struct sa_defrag_extent_backref *backref)
+{
+	struct rb_node **p = &root->rb_node;
+	struct rb_node *parent = NULL;
+	struct sa_defrag_extent_backref *entry;
+	int ret;
+
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct sa_defrag_extent_backref, node);
+
+		ret = backref_comp(backref, entry);
+		if (ret < 0)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+
+	rb_link_node(&backref->node, parent, p);
+	rb_insert_color(&backref->node, root);
+}
+
+/*
+ * Note the backref might has changed, and in this case we just return 0.
+ */
+static noinline int record_one_backref(u64 inum, u64 offset, u64 root_id,
+				       void *ctx)
+{
+	struct btrfs_file_extent_item *extent;
+	struct old_sa_defrag_extent *old = ctx;
+	struct new_sa_defrag_extent *new = old->new;
+	struct btrfs_path *path = new->path;
+	struct btrfs_key key;
+	struct btrfs_root *root;
+	struct sa_defrag_extent_backref *backref;
+	struct extent_buffer *leaf;
+	struct inode *inode = new->inode;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	int slot;
+	int ret;
+	u64 extent_offset;
+	u64 num_bytes;
+
+	if (BTRFS_I(inode)->root->root_key.objectid == root_id &&
+	    inum == btrfs_ino(BTRFS_I(inode)))
+		return 0;
+
+	key.objectid = root_id;
+	key.type = BTRFS_ROOT_ITEM_KEY;
+	key.offset = (u64)-1;
+
+	root = btrfs_read_fs_root_no_name(fs_info, &key);
+	if (IS_ERR(root)) {
+		if (PTR_ERR(root) == -ENOENT)
+			return 0;
+		WARN_ON(1);
+		btrfs_debug(fs_info, "inum=%llu, offset=%llu, root_id=%llu",
+			 inum, offset, root_id);
+		return PTR_ERR(root);
+	}
+
+	key.objectid = inum;
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	if (offset > (u64)-1 << 32)
+		key.offset = 0;
+	else
+		key.offset = offset;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (WARN_ON(ret < 0))
+		return ret;
+	ret = 0;
+
+	while (1) {
+		cond_resched();
+
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0) {
+				goto out;
+			} else if (ret > 0) {
+				ret = 0;
+				goto out;
+			}
+			continue;
+		}
+
+		path->slots[0]++;
+
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+
+		if (key.objectid > inum)
+			goto out;
+
+		if (key.objectid < inum || key.type != BTRFS_EXTENT_DATA_KEY)
+			continue;
+
+		extent = btrfs_item_ptr(leaf, slot,
+					struct btrfs_file_extent_item);
+
+		if (btrfs_file_extent_disk_bytenr(leaf, extent) != old->bytenr)
+			continue;
+
+		/*
+		 * 'offset' refers to the exact key.offset,
+		 * NOT the 'offset' field in btrfs_extent_data_ref, ie.
+		 * (key.offset - extent_offset).
+		 */
+		if (key.offset != offset)
+			continue;
+
+		extent_offset = btrfs_file_extent_offset(leaf, extent);
+		num_bytes = btrfs_file_extent_num_bytes(leaf, extent);
+
+		if (extent_offset >= old->extent_offset + old->offset +
+		    old->len || extent_offset + num_bytes <=
+		    old->extent_offset + old->offset)
+			continue;
+		break;
+	}
+
+	backref = kmalloc(sizeof(*backref), GFP_NOFS);
+	if (!backref) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	backref->root_id = root_id;
+	backref->inum = inum;
+	backref->file_pos = offset;
+	backref->num_bytes = num_bytes;
+	backref->extent_offset = extent_offset;
+	backref->generation = btrfs_file_extent_generation(leaf, extent);
+	backref->old = old;
+	backref_insert(&new->root, backref);
+	old->count++;
+out:
+	btrfs_release_path(path);
+	WARN_ON(ret);
+	return ret;
+}
+
+static noinline bool record_extent_backrefs(struct btrfs_path *path,
+				   struct new_sa_defrag_extent *new)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(new->inode->i_sb);
+	struct old_sa_defrag_extent *old, *tmp;
+	int ret;
+
+	new->path = path;
+
+	list_for_each_entry_safe(old, tmp, &new->head, list) {
+		ret = iterate_inodes_from_logical(old->bytenr +
+						  old->extent_offset, fs_info,
+						  path, record_one_backref,
+						  old, false);
+		if (ret < 0 && ret != -ENOENT)
+			return false;
+
+		/* no backref to be processed for this extent */
+		if (!old->count) {
+			list_del(&old->list);
+			kfree(old);
+		}
+	}
+
+	if (list_empty(&new->head))
+		return false;
+
+	return true;
+}
+
+static int relink_is_mergable(struct extent_buffer *leaf,
+			      struct btrfs_file_extent_item *fi,
+			      struct new_sa_defrag_extent *new)
+{
+	if (btrfs_file_extent_disk_bytenr(leaf, fi) != new->bytenr)
+		return 0;
+
+	if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
+		return 0;
+
+	if (btrfs_file_extent_compression(leaf, fi) != new->compress_type)
+		return 0;
+
+	if (btrfs_file_extent_encryption(leaf, fi) ||
+	    btrfs_file_extent_other_encoding(leaf, fi))
+		return 0;
+
+	return 1;
+}
+
+/*
+ * Note the backref might has changed, and in this case we just return 0.
+ */
+static noinline int relink_extent_backref(struct btrfs_path *path,
+				 struct sa_defrag_extent_backref *prev,
+				 struct sa_defrag_extent_backref *backref)
+{
+	struct btrfs_file_extent_item *extent;
+	struct btrfs_file_extent_item *item;
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root;
+	struct btrfs_key key;
+	struct extent_buffer *leaf;
+	struct old_sa_defrag_extent *old = backref->old;
+	struct new_sa_defrag_extent *new = old->new;
+	struct btrfs_fs_info *fs_info = btrfs_sb(new->inode->i_sb);
+	struct inode *inode;
+	struct extent_state *cached = NULL;
+	int ret = 0;
+	u64 start;
+	u64 len;
+	u64 lock_start;
+	u64 lock_end;
+	bool merge = false;
+	int index;
+
+	if (prev && prev->root_id == backref->root_id &&
+	    prev->inum == backref->inum &&
+	    prev->file_pos + prev->num_bytes == backref->file_pos)
+		merge = true;
+
+	/* step 1: get root */
+	key.objectid = backref->root_id;
+	key.type = BTRFS_ROOT_ITEM_KEY;
+	key.offset = (u64)-1;
+
+	index = srcu_read_lock(&fs_info->subvol_srcu);
+
+	root = btrfs_read_fs_root_no_name(fs_info, &key);
+	if (IS_ERR(root)) {
+		srcu_read_unlock(&fs_info->subvol_srcu, index);
+		if (PTR_ERR(root) == -ENOENT)
+			return 0;
+		return PTR_ERR(root);
+	}
+
+	if (btrfs_root_readonly(root)) {
+		srcu_read_unlock(&fs_info->subvol_srcu, index);
+		return 0;
+	}
+
+	/* step 2: get inode */
+	key.objectid = backref->inum;
+	key.type = BTRFS_INODE_ITEM_KEY;
+	key.offset = 0;
+
+	inode = btrfs_iget(fs_info->sb, &key, root, NULL);
+	if (IS_ERR(inode)) {
+		srcu_read_unlock(&fs_info->subvol_srcu, index);
+		return 0;
+	}
+
+	srcu_read_unlock(&fs_info->subvol_srcu, index);
+
+	/* step 3: relink backref */
+	lock_start = backref->file_pos;
+	lock_end = backref->file_pos + backref->num_bytes - 1;
+	lock_extent_bits(&BTRFS_I(inode)->io_tree, lock_start, lock_end,
+			 &cached);
+
+	ordered = btrfs_lookup_first_ordered_extent(inode, lock_end);
+	if (ordered) {
+		btrfs_put_ordered_extent(ordered);
+		goto out_unlock;
+	}
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_unlock;
+	}
+
+	key.objectid = backref->inum;
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = backref->file_pos;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0) {
+		goto out_free_path;
+	} else if (ret > 0) {
+		ret = 0;
+		goto out_free_path;
+	}
+
+	extent = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				struct btrfs_file_extent_item);
+
+	if (btrfs_file_extent_generation(path->nodes[0], extent) !=
+	    backref->generation)
+		goto out_free_path;
+
+	btrfs_release_path(path);
+
+	start = backref->file_pos;
+	if (backref->extent_offset < old->extent_offset + old->offset)
+		start += old->extent_offset + old->offset -
+			 backref->extent_offset;
+
+	len = min(backref->extent_offset + backref->num_bytes,
+		  old->extent_offset + old->offset + old->len);
+	len -= max(backref->extent_offset, old->extent_offset + old->offset);
+
+	ret = btrfs_drop_extents(trans, root, inode, start,
+				 start + len, 1);
+	if (ret)
+		goto out_free_path;
+again:
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = start;
+
+	path->leave_spinning = 1;
+	if (merge) {
+		struct btrfs_file_extent_item *fi;
+		u64 extent_len;
+		struct btrfs_key found_key;
+
+		ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+		if (ret < 0)
+			goto out_free_path;
+
+		path->slots[0]--;
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		fi = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_file_extent_item);
+		extent_len = btrfs_file_extent_num_bytes(leaf, fi);
+
+		if (extent_len + found_key.offset == start &&
+		    relink_is_mergable(leaf, fi, new)) {
+			btrfs_set_file_extent_num_bytes(leaf, fi,
+							extent_len + len);
+			btrfs_mark_buffer_dirty(leaf);
+			inode_add_bytes(inode, len);
+
+			ret = 1;
+			goto out_free_path;
+		} else {
+			merge = false;
+			btrfs_release_path(path);
+			goto again;
+		}
+	}
+
+	ret = btrfs_insert_empty_item(trans, root, path, &key,
+					sizeof(*extent));
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_free_path;
+	}
+
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0],
+				struct btrfs_file_extent_item);
+	btrfs_set_file_extent_disk_bytenr(leaf, item, new->bytenr);
+	btrfs_set_file_extent_disk_num_bytes(leaf, item, new->disk_len);
+	btrfs_set_file_extent_offset(leaf, item, start - new->file_pos);
+	btrfs_set_file_extent_num_bytes(leaf, item, len);
+	btrfs_set_file_extent_ram_bytes(leaf, item, new->len);
+	btrfs_set_file_extent_generation(leaf, item, trans->transid);
+	btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
+	btrfs_set_file_extent_compression(leaf, item, new->compress_type);
+	btrfs_set_file_extent_encryption(leaf, item, 0);
+	btrfs_set_file_extent_other_encoding(leaf, item, 0);
+
+	btrfs_mark_buffer_dirty(leaf);
+	inode_add_bytes(inode, len);
+	btrfs_release_path(path);
+
+	ret = btrfs_inc_extent_ref(trans, root, new->bytenr,
+			new->disk_len, 0,
+			backref->root_id, backref->inum,
+			new->file_pos);	/* start - extent_offset */
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_free_path;
+	}
+
+	ret = 1;
+out_free_path:
+	btrfs_release_path(path);
+	path->leave_spinning = 0;
+	btrfs_end_transaction(trans);
+out_unlock:
+	unlock_extent_cached(&BTRFS_I(inode)->io_tree, lock_start, lock_end,
+			     &cached);
+	iput(inode);
+	return ret;
+}
+
+static void free_sa_defrag_extent(struct new_sa_defrag_extent *new)
+{
+	struct old_sa_defrag_extent *old, *tmp;
+
+	if (!new)
+		return;
+
+	list_for_each_entry_safe(old, tmp, &new->head, list) {
+		kfree(old);
+	}
+	kfree(new);
+}
+
+static void relink_file_extents(struct new_sa_defrag_extent *new)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(new->inode->i_sb);
+	struct btrfs_path *path;
+	struct sa_defrag_extent_backref *backref;
+	struct sa_defrag_extent_backref *prev = NULL;
+	struct inode *inode;
+	struct rb_node *node;
+	int ret;
+
+	inode = new->inode;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return;
+
+	if (!record_extent_backrefs(path, new)) {
+		btrfs_free_path(path);
+		goto out;
+	}
+	btrfs_release_path(path);
+
+	while (1) {
+		node = rb_first(&new->root);
+		if (!node)
+			break;
+		rb_erase(node, &new->root);
+
+		backref = rb_entry(node, struct sa_defrag_extent_backref, node);
+
+		ret = relink_extent_backref(path, prev, backref);
+		WARN_ON(ret < 0);
+
+		kfree(prev);
+
+		if (ret == 1)
+			prev = backref;
+		else
+			prev = NULL;
+		cond_resched();
+	}
+	kfree(prev);
+
+	btrfs_free_path(path);
+out:
+	free_sa_defrag_extent(new);
+
+	atomic_dec(&fs_info->defrag_running);
+	wake_up(&fs_info->transaction_wait);
+}
+
+static struct new_sa_defrag_extent *
+record_old_file_extents(struct inode *inode,
+			struct btrfs_ordered_extent *ordered)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	struct old_sa_defrag_extent *old;
+	struct new_sa_defrag_extent *new;
+	int ret;
+
+	new = kmalloc(sizeof(*new), GFP_NOFS);
+	if (!new)
+		return NULL;
+
+	new->inode = inode;
+	new->file_pos = ordered->file_offset;
+	new->len = ordered->len;
+	new->bytenr = ordered->start;
+	new->disk_len = ordered->disk_len;
+	new->compress_type = ordered->compress_type;
+	new->root = RB_ROOT;
+	INIT_LIST_HEAD(&new->head);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		goto out_kfree;
+
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = new->file_pos;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out_free_path;
+	if (ret > 0 && path->slots[0] > 0)
+		path->slots[0]--;
+
+	/* find out all the old extents for the file range */
+	while (1) {
+		struct btrfs_file_extent_item *extent;
+		struct extent_buffer *l;
+		int slot;
+		u64 num_bytes;
+		u64 offset;
+		u64 end;
+		u64 disk_bytenr;
+		u64 extent_offset;
+
+		l = path->nodes[0];
+		slot = path->slots[0];
+
+		if (slot >= btrfs_header_nritems(l)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out_free_path;
+			else if (ret > 0)
+				break;
+			continue;
+		}
+
+		btrfs_item_key_to_cpu(l, &key, slot);
+
+		if (key.objectid != btrfs_ino(BTRFS_I(inode)))
+			break;
+		if (key.type != BTRFS_EXTENT_DATA_KEY)
+			break;
+		if (key.offset >= new->file_pos + new->len)
+			break;
+
+		extent = btrfs_item_ptr(l, slot, struct btrfs_file_extent_item);
+
+		num_bytes = btrfs_file_extent_num_bytes(l, extent);
+		if (key.offset + num_bytes < new->file_pos)
+			goto next;
+
+		disk_bytenr = btrfs_file_extent_disk_bytenr(l, extent);
+		if (!disk_bytenr)
+			goto next;
+
+		extent_offset = btrfs_file_extent_offset(l, extent);
+
+		old = kmalloc(sizeof(*old), GFP_NOFS);
+		if (!old)
+			goto out_free_path;
+
+		offset = max(new->file_pos, key.offset);
+		end = min(new->file_pos + new->len, key.offset + num_bytes);
+
+		old->bytenr = disk_bytenr;
+		old->extent_offset = extent_offset;
+		old->offset = offset - key.offset;
+		old->len = end - offset;
+		old->new = new;
+		old->count = 0;
+		list_add_tail(&old->list, &new->head);
+next:
+		path->slots[0]++;
+		cond_resched();
+	}
+
+	btrfs_free_path(path);
+	atomic_inc(&fs_info->defrag_running);
+
+	return new;
+
+out_free_path:
+	btrfs_free_path(path);
+out_kfree:
+	free_sa_defrag_extent(new);
+	return NULL;
+}
+
+static void btrfs_release_delalloc_bytes(struct btrfs_fs_info *fs_info,
+					 u64 start, u64 len)
+{
+	struct btrfs_block_group_cache *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);
+}
+
+/* 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.
+ */
+static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
+{
+	struct inode *inode = ordered_extent->inode;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans = NULL;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_state *cached_state = NULL;
+	struct new_sa_defrag_extent *new = NULL;
+	int compress_type = 0;
+	int ret = 0;
+	u64 logical_len = ordered_extent->len;
+	bool nolock;
+	bool truncated = false;
+	bool range_locked = false;
+	bool clear_new_delalloc_bytes = false;
+	bool clear_reserved_extent = true;
+
+	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))
+		clear_new_delalloc_bytes = true;
+
+	nolock = btrfs_is_free_space_inode(BTRFS_I(inode));
+
+	if (test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags)) {
+		ret = -EIO;
+		goto out;
+	}
+
+	btrfs_free_io_failure_record(BTRFS_I(inode),
+			ordered_extent->file_offset,
+			ordered_extent->file_offset +
+			ordered_extent->len - 1);
+
+	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 */
+
+		/*
+		 * For mwrite(mmap + memset to write) case, we still reserve
+		 * space for NOCOW range.
+		 * As NOCOW won't cause a new delayed ref, just free the space
+		 */
+		btrfs_qgroup_free_data(inode, NULL, ordered_extent->file_offset,
+				       ordered_extent->len);
+		btrfs_ordered_update_i_size(inode, 0, ordered_extent);
+		if (nolock)
+			trans = btrfs_join_transaction_nolock(root);
+		else
+			trans = btrfs_join_transaction(root);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			trans = NULL;
+			goto out;
+		}
+		trans->block_rsv = &BTRFS_I(inode)->block_rsv;
+		ret = btrfs_update_inode_fallback(trans, root, inode);
+		if (ret) /* -ENOMEM or corruption */
+			btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	range_locked = true;
+	lock_extent_bits(io_tree, ordered_extent->file_offset,
+			 ordered_extent->file_offset + ordered_extent->len - 1,
+			 &cached_state);
+
+	ret = test_range_bit(io_tree, ordered_extent->file_offset,
+			ordered_extent->file_offset + ordered_extent->len - 1,
+			EXTENT_DEFRAG, 0, cached_state);
+	if (ret) {
+		u64 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
+		if (0 && last_snapshot >= BTRFS_I(inode)->generation)
+			/* the inode is shared */
+			new = record_old_file_extents(inode, ordered_extent);
+
+		clear_extent_bit(io_tree, ordered_extent->file_offset,
+			ordered_extent->file_offset + ordered_extent->len - 1,
+			EXTENT_DEFRAG, 0, 0, &cached_state);
+	}
+
+	if (nolock)
+		trans = btrfs_join_transaction_nolock(root);
+	else
+		trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		trans = NULL;
+		goto out;
+	}
+
+	trans->block_rsv = &BTRFS_I(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);
+		btrfs_qgroup_free_data(inode, NULL, ordered_extent->file_offset,
+				       ordered_extent->len);
+		ret = btrfs_mark_extent_written(trans, BTRFS_I(inode),
+						ordered_extent->file_offset,
+						ordered_extent->file_offset +
+						logical_len);
+	} else {
+		BUG_ON(root == fs_info->tree_root);
+		ret = insert_reserved_file_extent(trans, inode,
+						ordered_extent->file_offset,
+						ordered_extent->start,
+						ordered_extent->disk_len,
+						logical_len, logical_len,
+						compress_type, 0, 0,
+						BTRFS_FILE_EXTENT_REG);
+		if (!ret) {
+			clear_reserved_extent = false;
+			btrfs_release_delalloc_bytes(fs_info,
+						     ordered_extent->start,
+						     ordered_extent->disk_len);
+		}
+	}
+	unpin_extent_cache(&BTRFS_I(inode)->extent_tree,
+			   ordered_extent->file_offset, ordered_extent->len,
+			   trans->transid);
+	if (ret < 0) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	ret = add_pending_csums(trans, inode, &ordered_extent->list);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	btrfs_ordered_update_i_size(inode, 0, ordered_extent);
+	ret = btrfs_update_inode_fallback(trans, root, inode);
+	if (ret) { /* -ENOMEM or corruption */
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+	ret = 0;
+out:
+	if (range_locked || clear_new_delalloc_bytes) {
+		unsigned int clear_bits = 0;
+
+		if (range_locked)
+			clear_bits |= EXTENT_LOCKED;
+		if (clear_new_delalloc_bytes)
+			clear_bits |= EXTENT_DELALLOC_NEW;
+		clear_extent_bit(&BTRFS_I(inode)->io_tree,
+				 ordered_extent->file_offset,
+				 ordered_extent->file_offset +
+				 ordered_extent->len - 1,
+				 clear_bits,
+				 (clear_bits & EXTENT_LOCKED) ? 1 : 0,
+				 0, &cached_state);
+	}
+
+	if (trans)
+		btrfs_end_transaction(trans);
+
+	if (ret || truncated) {
+		u64 start, end;
+
+		/*
+		 * 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)
+			start = ordered_extent->file_offset + logical_len;
+		else
+			start = ordered_extent->file_offset;
+		end = ordered_extent->file_offset + ordered_extent->len - 1;
+		clear_extent_uptodate(io_tree, start, end, NULL);
+
+		/* Drop the cache for the part of the extent we didn't write. */
+		btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
+
+		/*
+		 * 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))
+			btrfs_free_reserved_extent(fs_info,
+						   ordered_extent->start,
+						   ordered_extent->disk_len, 1);
+	}
+
+
+	/*
+	 * 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);
+
+	/* for snapshot-aware defrag */
+	if (new) {
+		if (ret) {
+			free_sa_defrag_extent(new);
+			atomic_dec(&fs_info->defrag_running);
+		} else {
+			relink_file_extents(new);
+		}
+	}
+
+	/* once for us */
+	btrfs_put_ordered_extent(ordered_extent);
+	/* once for the tree */
+	btrfs_put_ordered_extent(ordered_extent);
+
+	return ret;
+}
+
+static void finish_ordered_fn(struct btrfs_work *work)
+{
+	struct btrfs_ordered_extent *ordered_extent;
+	ordered_extent = container_of(work, struct btrfs_ordered_extent, work);
+	btrfs_finish_ordered_io(ordered_extent);
+}
+
+static void btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end,
+				struct extent_state *state, int uptodate)
+{
+	struct inode *inode = page->mapping->host;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_ordered_extent *ordered_extent = NULL;
+	struct btrfs_workqueue *wq;
+	btrfs_work_func_t func;
+
+	trace_btrfs_writepage_end_io_hook(page, start, end, uptodate);
+
+	ClearPagePrivate2(page);
+	if (!btrfs_dec_test_ordered_pending(inode, &ordered_extent, start,
+					    end - start + 1, uptodate))
+		return;
+
+	if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
+		wq = fs_info->endio_freespace_worker;
+		func = btrfs_freespace_write_helper;
+	} else {
+		wq = fs_info->endio_write_workers;
+		func = btrfs_endio_write_helper;
+	}
+
+	btrfs_init_work(&ordered_extent->work, func, finish_ordered_fn, NULL,
+			NULL);
+	btrfs_queue_work(wq, &ordered_extent->work);
+}
+
+static int __readpage_endio_check(struct inode *inode,
+				  struct btrfs_io_bio *io_bio,
+				  int icsum, struct page *page,
+				  int pgoff, u64 start, size_t len)
+{
+	char *kaddr;
+	u32 csum_expected;
+	u32 csum = ~(u32)0;
+
+	csum_expected = *(((u32 *)io_bio->csum) + icsum);
+
+	kaddr = kmap_atomic(page);
+	csum = btrfs_csum_data(kaddr + pgoff, csum,  len);
+	btrfs_csum_final(csum, (u8 *)&csum);
+	if (csum != csum_expected)
+		goto zeroit;
+
+	kunmap_atomic(kaddr);
+	return 0;
+zeroit:
+	btrfs_print_data_csum_error(BTRFS_I(inode), start, csum, csum_expected,
+				    io_bio->mirror_num);
+	memset(kaddr + pgoff, 1, len);
+	flush_dcache_page(page);
+	kunmap_atomic(kaddr);
+	return -EIO;
+}
+
+/*
+ * when reads are done, we need to check csums to verify the data is correct
+ * if there's a match, we allow the bio to finish.  If not, the code in
+ * extent_io.c will try to find good copies for us.
+ */
+static int btrfs_readpage_end_io_hook(struct btrfs_io_bio *io_bio,
+				      u64 phy_offset, struct page *page,
+				      u64 start, u64 end, int mirror)
+{
+	size_t offset = start - page_offset(page);
+	struct inode *inode = page->mapping->host;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+
+	if (PageChecked(page)) {
+		ClearPageChecked(page);
+		return 0;
+	}
+
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
+		return 0;
+
+	if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID &&
+	    test_range_bit(io_tree, start, end, EXTENT_NODATASUM, 1, NULL)) {
+		clear_extent_bits(io_tree, start, end, EXTENT_NODATASUM);
+		return 0;
+	}
+
+	phy_offset >>= inode->i_sb->s_blocksize_bits;
+	return __readpage_endio_check(inode, io_bio, phy_offset, page, offset,
+				      start, (size_t)(end - start + 1));
+}
+
+/*
+ * 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 inode *inode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_inode *binode = BTRFS_I(inode);
+
+	if (atomic_add_unless(&inode->i_count, -1, 1))
+		return;
+
+	spin_lock(&fs_info->delayed_iput_lock);
+	ASSERT(list_empty(&binode->delayed_iput));
+	list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs);
+	spin_unlock(&fs_info->delayed_iput_lock);
+}
+
+void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info)
+{
+
+	spin_lock(&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);
+		list_del_init(&inode->delayed_iput);
+		spin_unlock(&fs_info->delayed_iput_lock);
+		iput(&inode->vfs_inode);
+		spin_lock(&fs_info->delayed_iput_lock);
+	}
+	spin_unlock(&fs_info->delayed_iput_lock);
+}
+
+/*
+ * 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 (cmpxchg(&root->orphan_cleanup_state, 0, ORPHAN_CLEANUP_STARTED))
+		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) {
+			btrfs_err(fs_info,
+				  "Error removing orphan entry, stopping orphan cleanup");
+			ret = -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, &found_key, root, NULL);
+		ret = PTR_ERR_OR_ZERO(inode);
+		if (ret && ret != -ENOENT)
+			goto out;
+
+		if (ret == -ENOENT && root == fs_info->tree_root) {
+			struct btrfs_root *dead_root;
+			struct btrfs_fs_info *fs_info = root->fs_info;
+			int is_dead_root = 0;
+
+			/*
+			 * this is an orphan in the tree root. Currently these
+			 * could come from 2 sources:
+			 *  a) a snapshot deletion in progress
+			 *  b) a free space cache inode
+			 * We need to distinguish those two, as the snapshot
+			 * orphan must not get deleted.
+			 * find_dead_roots already ran before us, so if this
+			 * is a snapshot deletion, we should find the root
+			 * in the dead_roots list
+			 */
+			spin_lock(&fs_info->trans_lock);
+			list_for_each_entry(dead_root, &fs_info->dead_roots,
+					    root_list) {
+				if (dead_root->root_key.objectid ==
+				    found_key.objectid) {
+					is_dead_root = 1;
+					break;
+				}
+			}
+			spin_unlock(&fs_info->trans_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. 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 (ret == -ENOENT || inode->i_nlink) {
+			if (!ret)
+				iput(inode);
+			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);
+		if (ret)
+			goto out;
+	}
+	/* release the path since we're done with it */
+	btrfs_release_path(path);
+
+	root->orphan_cleanup_state = ORPHAN_CLEANUP_DONE;
+
+	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));
+
+	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->i_ctime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->ctime);
+	inode->i_ctime.tv_nsec = 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_I(inode)->flags = btrfs_inode_flags(leaf, inode_item);
+
+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;
+	/*
+	 * Similar reasoning for last_link_trans, needs to be set otherwise
+	 * for a case like the following:
+	 *
+	 * mkdir A
+	 * touch foo
+	 * ln foo A/bar
+	 * echo 2 > /proc/sys/vm/drop_caches
+	 * fsync foo
+	 * <power failure>
+	 *
+	 * Would result in link bar and directory A not existing after the power
+	 * failure.
+	 */
+	BTRFS_I(inode)->last_link_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;
+		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
+		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_symlink_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;
+
+	btrfs_init_map_token(&token);
+
+	btrfs_set_token_inode_uid(leaf, item, i_uid_read(inode), &token);
+	btrfs_set_token_inode_gid(leaf, item, i_gid_read(inode), &token);
+	btrfs_set_token_inode_size(leaf, item, BTRFS_I(inode)->disk_i_size,
+				   &token);
+	btrfs_set_token_inode_mode(leaf, item, inode->i_mode, &token);
+	btrfs_set_token_inode_nlink(leaf, item, inode->i_nlink, &token);
+
+	btrfs_set_token_timespec_sec(leaf, &item->atime,
+				     inode->i_atime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->atime,
+				      inode->i_atime.tv_nsec, &token);
+
+	btrfs_set_token_timespec_sec(leaf, &item->mtime,
+				     inode->i_mtime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->mtime,
+				      inode->i_mtime.tv_nsec, &token);
+
+	btrfs_set_token_timespec_sec(leaf, &item->ctime,
+				     inode->i_ctime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->ctime,
+				      inode->i_ctime.tv_nsec, &token);
+
+	btrfs_set_token_timespec_sec(leaf, &item->otime,
+				     BTRFS_I(inode)->i_otime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->otime,
+				      BTRFS_I(inode)->i_otime.tv_nsec, &token);
+
+	btrfs_set_token_inode_nbytes(leaf, item, inode_get_bytes(inode),
+				     &token);
+	btrfs_set_token_inode_generation(leaf, item, BTRFS_I(inode)->generation,
+					 &token);
+	btrfs_set_token_inode_sequence(leaf, item, inode_peek_iversion(inode),
+				       &token);
+	btrfs_set_token_inode_transid(leaf, item, trans->transid, &token);
+	btrfs_set_token_inode_rdev(leaf, item, inode->i_rdev, &token);
+	btrfs_set_token_inode_flags(leaf, item, BTRFS_I(inode)->flags, &token);
+	btrfs_set_token_inode_block_group(leaf, item, 0, &token);
+}
+
+/*
+ * 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 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;
+
+	path->leave_spinning = 1;
+	ret = btrfs_lookup_inode(trans, root, path, &BTRFS_I(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);
+	btrfs_mark_buffer_dirty(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 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(BTRFS_I(inode))
+	    && root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID
+	    && !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);
+}
+
+noinline int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
+					 struct btrfs_root *root,
+					 struct 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_root *root,
+				struct btrfs_inode *dir,
+				struct btrfs_inode *inode,
+				const char *name, int name_len)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_path *path;
+	int ret = 0;
+	struct extent_buffer *leaf;
+	struct btrfs_dir_item *di;
+	struct btrfs_key key;
+	u64 index;
+	u64 ino = btrfs_ino(inode);
+	u64 dir_ino = btrfs_ino(dir);
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	path->leave_spinning = 1;
+	di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
+				    name, name_len, -1);
+	if (IS_ERR(di)) {
+		ret = PTR_ERR(di);
+		goto err;
+	}
+	if (!di) {
+		ret = -ENOENT;
+		goto err;
+	}
+	leaf = path->nodes[0];
+	btrfs_dir_item_key_to_cpu(leaf, di, &key);
+	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, name_len, ino,
+				  dir_ino, &index);
+	if (ret) {
+		btrfs_info(fs_info,
+			"failed to delete reference to %.*s, inode %llu parent %llu",
+			name_len, name, ino, dir_ino);
+		btrfs_abort_transaction(trans, ret);
+		goto err;
+	}
+skip_backref:
+	ret = btrfs_delete_delayed_dir_index(trans, dir, index);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto err;
+	}
+
+	ret = btrfs_del_inode_ref_in_log(trans, root, name, name_len, inode,
+			dir_ino);
+	if (ret != 0 && ret != -ENOENT) {
+		btrfs_abort_transaction(trans, ret);
+		goto err;
+	}
+
+	ret = btrfs_del_dir_entries_in_log(trans, root, name, name_len, dir,
+			index);
+	if (ret == -ENOENT)
+		ret = 0;
+	else if (ret)
+		btrfs_abort_transaction(trans, ret);
+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->vfs_inode.i_ctime = dir->vfs_inode.i_mtime =
+		dir->vfs_inode.i_ctime = current_time(&inode->vfs_inode);
+	ret = btrfs_update_inode(trans, root, &dir->vfs_inode);
+out:
+	return ret;
+}
+
+int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+		       struct btrfs_root *root,
+		       struct btrfs_inode *dir, struct btrfs_inode *inode,
+		       const char *name, int name_len)
+{
+	int ret;
+	ret = __btrfs_unlink_inode(trans, root, dir, inode, name, name_len);
+	if (!ret) {
+		drop_nlink(&inode->vfs_inode);
+		ret = btrfs_update_inode(trans, root, &inode->vfs_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 inode *dir)
+{
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+
+	/*
+	 * 1 for the possible orphan item
+	 * 1 for the dir item
+	 * 1 for the dir index
+	 * 1 for the inode ref
+	 * 1 for the inode
+	 */
+	return btrfs_start_transaction_fallback_global_rsv(root, 5, 5);
+}
+
+static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_trans_handle *trans;
+	struct inode *inode = d_inode(dentry);
+	int ret;
+
+	trans = __unlink_start_trans(dir);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	btrfs_record_unlink_dir(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
+			0);
+
+	ret = btrfs_unlink_inode(trans, root, BTRFS_I(dir),
+			BTRFS_I(d_inode(dentry)), dentry->d_name.name,
+			dentry->d_name.len);
+	if (ret)
+		goto out;
+
+	if (inode->i_nlink == 0) {
+		ret = btrfs_orphan_add(trans, BTRFS_I(inode));
+		if (ret)
+			goto out;
+	}
+
+out:
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(root->fs_info);
+	return ret;
+}
+
+static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
+			       struct inode *dir, struct dentry *dentry)
+{
+	struct btrfs_root *root = BTRFS_I(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;
+	const char *name = dentry->d_name.name;
+	int name_len = dentry->d_name.len;
+	u64 index;
+	int ret;
+	u64 objectid;
+	u64 dir_ino = btrfs_ino(BTRFS_I(dir));
+
+	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);
+		return -EINVAL;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
+				   name, name_len, -1);
+	if (IS_ERR_OR_NULL(di)) {
+		if (!di)
+			ret = -ENOENT;
+		else
+			ret = PTR_ERR(di);
+		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 incorret.
+	 * 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,
+						 name, name_len);
+		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, name, name_len);
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+	}
+
+	ret = btrfs_delete_delayed_dir_index(trans, BTRFS_I(dir), index);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	btrfs_i_size_write(BTRFS_I(dir), dir->i_size - name_len * 2);
+	inode_inc_iversion(dir);
+	dir->i_mtime = dir->i_ctime = current_time(dir);
+	ret = btrfs_update_inode_fallback(trans, root, dir);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+out:
+	btrfs_free_path(path);
+	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;
+	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, "default", 7, 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 (!test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
+		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 inode *dir, struct dentry *dentry)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
+	struct btrfs_root *root = BTRFS_I(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;
+	int err;
+
+	/*
+	 * 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);
+	root_flags = btrfs_root_flags(&dest->root_item);
+	if (dest->send_in_progress == 0) {
+		btrfs_set_root_flags(&dest->root_item,
+				root_flags | BTRFS_ROOT_SUBVOL_DEAD);
+		spin_unlock(&dest->root_item_lock);
+	} else {
+		spin_unlock(&dest->root_item_lock);
+		btrfs_warn(fs_info,
+			   "attempt to delete subvolume %llu during send",
+			   dest->root_key.objectid);
+		return -EPERM;
+	}
+
+	down_write(&fs_info->subvol_sem);
+
+	err = may_destroy_subvol(dest);
+	if (err)
+		goto out_up_write;
+
+	btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
+	/*
+	 * One for dir inode,
+	 * two for dir entries,
+	 * two for root ref/backref.
+	 */
+	err = btrfs_subvolume_reserve_metadata(root, &block_rsv, 5, true);
+	if (err)
+		goto out_up_write;
+
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		err = PTR_ERR(trans);
+		goto out_release;
+	}
+	trans->block_rsv = &block_rsv;
+	trans->bytes_reserved = block_rsv.size;
+
+	btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));
+
+	ret = btrfs_unlink_subvol(trans, dir, dentry);
+	if (ret) {
+		err = ret;
+		btrfs_abort_transaction(trans, ret);
+		goto out_end_trans;
+	}
+
+	btrfs_record_root_in_trans(trans, dest);
+
+	memset(&dest->root_item.drop_progress, 0,
+		sizeof(dest->root_item.drop_progress));
+	dest->root_item.drop_level = 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);
+			err = 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);
+		err = 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);
+			err = 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);
+	if (ret && !err)
+		err = ret;
+	inode->i_flags |= S_DEAD;
+out_release:
+	btrfs_subvolume_release_metadata(fs_info, &block_rsv);
+out_up_write:
+	up_write(&fs_info->subvol_sem);
+	if (err) {
+		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);
+	} else {
+		d_invalidate(dentry);
+		btrfs_prune_dentries(dest);
+		ASSERT(dest->send_in_progress == 0);
+
+		/* the last ref */
+		if (dest->ino_cache_inode) {
+			iput(dest->ino_cache_inode);
+			dest->ino_cache_inode = NULL;
+		}
+	}
+
+	return err;
+}
+
+static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+	int err = 0;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_trans_handle *trans;
+	u64 last_unlink_trans;
+
+	if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
+		return -ENOTEMPTY;
+	if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID)
+		return btrfs_delete_subvolume(dir, dentry);
+
+	trans = __unlink_start_trans(dir);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
+		err = btrfs_unlink_subvol(trans, 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, root, BTRFS_I(dir),
+			BTRFS_I(d_inode(dentry)), dentry->d_name.name,
+			dentry->d_name.len);
+	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);
+	btrfs_btree_balance_dirty(root->fs_info);
+
+	return err;
+}
+
+static int truncate_space_check(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				u64 bytes_deleted)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+
+	/*
+	 * This is only used to apply pressure to the enospc system, we don't
+	 * intend to use this reservation at all.
+	 */
+	bytes_deleted = btrfs_csum_bytes_to_leaves(fs_info, bytes_deleted);
+	bytes_deleted *= fs_info->nodesize;
+	ret = btrfs_block_rsv_add(root, &fs_info->trans_block_rsv,
+				  bytes_deleted, BTRFS_RESERVE_NO_FLUSH);
+	if (!ret) {
+		trace_btrfs_space_reservation(fs_info, "transaction",
+					      trans->transid,
+					      bytes_deleted, 1);
+		trans->bytes_reserved += bytes_deleted;
+	}
+	return ret;
+
+}
+
+/*
+ * Return this if we need to call truncate_block for the last bit of the
+ * truncate.
+ */
+#define NEED_TRUNCATE_BLOCK 1
+
+/*
+ * this can truncate away extent items, csum items and directory items.
+ * It starts at a high offset and removes keys until it can't find
+ * any higher than new_size
+ *
+ * csum items that cross the new i_size are truncated to the new size
+ * as well.
+ *
+ * min_type is the minimum key type to truncate down to.  If set to 0, this
+ * will kill all the items on this inode, including the INODE_ITEM_KEY.
+ */
+int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *root,
+			       struct inode *inode,
+			       u64 new_size, u32 min_type)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	u64 extent_start = 0;
+	u64 extent_num_bytes = 0;
+	u64 extent_offset = 0;
+	u64 item_end = 0;
+	u64 last_size = new_size;
+	u32 found_type = (u8)-1;
+	int found_extent;
+	int del_item;
+	int pending_del_nr = 0;
+	int pending_del_slot = 0;
+	int extent_type = -1;
+	int ret;
+	u64 ino = btrfs_ino(BTRFS_I(inode));
+	u64 bytes_deleted = 0;
+	bool be_nice = false;
+	bool should_throttle = false;
+	bool should_end = false;
+
+	BUG_ON(new_size > 0 && min_type != BTRFS_EXTENT_DATA_KEY);
+
+	/*
+	 * for non-free space inodes and ref cows, we want to back off from
+	 * time to time
+	 */
+	if (!btrfs_is_free_space_inode(BTRFS_I(inode)) &&
+	    test_bit(BTRFS_ROOT_REF_COWS, &root->state))
+		be_nice = true;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	path->reada = READA_BACK;
+
+	/*
+	 * 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.
+	 */
+	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
+	    root == fs_info->tree_root)
+		btrfs_drop_extent_cache(BTRFS_I(inode), ALIGN(new_size,
+					fs_info->sectorsize),
+					(u64)-1, 0);
+
+	/*
+	 * This function is also used to drop the items in the log tree before
+	 * we relog the inode, so if root != BTRFS_I(inode)->root, it means
+	 * it is used to drop the loged items. So we shouldn't kill the delayed
+	 * items.
+	 */
+	if (min_type == 0 && root == BTRFS_I(inode)->root)
+		btrfs_kill_delayed_inode_items(BTRFS_I(inode));
+
+	key.objectid = ino;
+	key.offset = (u64)-1;
+	key.type = (u8)-1;
+
+search_again:
+	/*
+	 * with a 16K leaf size and 128MB extents, you can actually queue
+	 * up a huge file in a single leaf.  Most of the time that
+	 * bytes_deleted is > 0, it will be huge by the time we get here
+	 */
+	if (be_nice && bytes_deleted > SZ_32M &&
+	    btrfs_should_end_transaction(trans)) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	path->leave_spinning = 1;
+	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+	if (ret < 0)
+		goto out;
+
+	if (ret > 0) {
+		ret = 0;
+		/* there are no items in the tree for us to truncate, we're
+		 * done
+		 */
+		if (path->slots[0] == 0)
+			goto out;
+		path->slots[0]--;
+	}
+
+	while (1) {
+		fi = NULL;
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		found_type = found_key.type;
+
+		if (found_key.objectid != ino)
+			break;
+
+		if (found_type < min_type)
+			break;
+
+		item_end = found_key.offset;
+		if (found_type == BTRFS_EXTENT_DATA_KEY) {
+			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) {
+				item_end +=
+				    btrfs_file_extent_num_bytes(leaf, fi);
+
+				trace_btrfs_truncate_show_fi_regular(
+					BTRFS_I(inode), leaf, fi,
+					found_key.offset);
+			} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+				item_end += btrfs_file_extent_ram_bytes(leaf,
+									fi);
+
+				trace_btrfs_truncate_show_fi_inline(
+					BTRFS_I(inode), leaf, fi, path->slots[0],
+					found_key.offset);
+			}
+			item_end--;
+		}
+		if (found_type > min_type) {
+			del_item = 1;
+		} else {
+			if (item_end < new_size)
+				break;
+			if (found_key.offset >= new_size)
+				del_item = 1;
+			else
+				del_item = 0;
+		}
+		found_extent = 0;
+		/* FIXME, shrink the extent if the ref count is only 1 */
+		if (found_type != BTRFS_EXTENT_DATA_KEY)
+			goto delete;
+
+		if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
+			u64 num_dec;
+			extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
+			if (!del_item) {
+				u64 orig_num_bytes =
+					btrfs_file_extent_num_bytes(leaf, fi);
+				extent_num_bytes = ALIGN(new_size -
+						found_key.offset,
+						fs_info->sectorsize);
+				btrfs_set_file_extent_num_bytes(leaf, fi,
+							 extent_num_bytes);
+				num_dec = (orig_num_bytes -
+					   extent_num_bytes);
+				if (test_bit(BTRFS_ROOT_REF_COWS,
+					     &root->state) &&
+				    extent_start != 0)
+					inode_sub_bytes(inode, num_dec);
+				btrfs_mark_buffer_dirty(leaf);
+			} else {
+				extent_num_bytes =
+					btrfs_file_extent_disk_num_bytes(leaf,
+									 fi);
+				extent_offset = found_key.offset -
+					btrfs_file_extent_offset(leaf, fi);
+
+				/* FIXME blocksize != 4096 */
+				num_dec = btrfs_file_extent_num_bytes(leaf, fi);
+				if (extent_start != 0) {
+					found_extent = 1;
+					if (test_bit(BTRFS_ROOT_REF_COWS,
+						     &root->state))
+						inode_sub_bytes(inode, num_dec);
+				}
+			}
+		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+			/*
+			 * we can't truncate inline items that have had
+			 * special encodings
+			 */
+			if (!del_item &&
+			    btrfs_file_extent_encryption(leaf, fi) == 0 &&
+			    btrfs_file_extent_other_encoding(leaf, fi) == 0 &&
+			    btrfs_file_extent_compression(leaf, fi) == 0) {
+				u32 size = (u32)(new_size - found_key.offset);
+
+				btrfs_set_file_extent_ram_bytes(leaf, fi, size);
+				size = btrfs_file_extent_calc_inline_size(size);
+				btrfs_truncate_item(root->fs_info, path, size, 1);
+			} else if (!del_item) {
+				/*
+				 * We have to bail so the last_size is set to
+				 * just before this extent.
+				 */
+				ret = NEED_TRUNCATE_BLOCK;
+				break;
+			}
+
+			if (test_bit(BTRFS_ROOT_REF_COWS, &root->state))
+				inode_sub_bytes(inode, item_end + 1 - new_size);
+		}
+delete:
+		if (del_item)
+			last_size = found_key.offset;
+		else
+			last_size = new_size;
+		if (del_item) {
+			if (!pending_del_nr) {
+				/* no pending yet, add ourselves */
+				pending_del_slot = path->slots[0];
+				pending_del_nr = 1;
+			} else if (pending_del_nr &&
+				   path->slots[0] + 1 == pending_del_slot) {
+				/* hop on the pending chunk */
+				pending_del_nr++;
+				pending_del_slot = path->slots[0];
+			} else {
+				BUG();
+			}
+		} else {
+			break;
+		}
+		should_throttle = false;
+
+		if (found_extent &&
+		    (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
+		     root == fs_info->tree_root)) {
+			btrfs_set_path_blocking(path);
+			bytes_deleted += extent_num_bytes;
+			ret = btrfs_free_extent(trans, root, extent_start,
+						extent_num_bytes, 0,
+						btrfs_header_owner(leaf),
+						ino, extent_offset);
+			if (ret) {
+				btrfs_abort_transaction(trans, ret);
+				break;
+			}
+			if (btrfs_should_throttle_delayed_refs(trans, fs_info))
+				btrfs_async_run_delayed_refs(fs_info,
+					trans->delayed_ref_updates * 2,
+					trans->transid, 0);
+			if (be_nice) {
+				if (truncate_space_check(trans, root,
+							 extent_num_bytes)) {
+					should_end = true;
+				}
+				if (btrfs_should_throttle_delayed_refs(trans,
+								       fs_info))
+					should_throttle = true;
+			}
+		}
+
+		if (found_type == BTRFS_INODE_ITEM_KEY)
+			break;
+
+		if (path->slots[0] == 0 ||
+		    path->slots[0] != pending_del_slot ||
+		    should_throttle || should_end) {
+			if (pending_del_nr) {
+				ret = btrfs_del_items(trans, root, path,
+						pending_del_slot,
+						pending_del_nr);
+				if (ret) {
+					btrfs_abort_transaction(trans, ret);
+					break;
+				}
+				pending_del_nr = 0;
+			}
+			btrfs_release_path(path);
+			if (should_throttle) {
+				unsigned long updates = trans->delayed_ref_updates;
+				if (updates) {
+					trans->delayed_ref_updates = 0;
+					ret = btrfs_run_delayed_refs(trans,
+								   updates * 2);
+					if (ret)
+						break;
+				}
+			}
+			/*
+			 * if we failed to refill our space rsv, bail out
+			 * and let the transaction restart
+			 */
+			if (should_end) {
+				ret = -EAGAIN;
+				break;
+			}
+			goto search_again;
+		} else {
+			path->slots[0]--;
+		}
+	}
+out:
+	if (ret >= 0 && pending_del_nr) {
+		int err;
+
+		err = btrfs_del_items(trans, root, path, pending_del_slot,
+				      pending_del_nr);
+		if (err) {
+			btrfs_abort_transaction(trans, err);
+			ret = err;
+		}
+	}
+	if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
+		ASSERT(last_size >= new_size);
+		if (!ret && last_size > new_size)
+			last_size = new_size;
+		btrfs_ordered_update_i_size(inode, last_size, NULL);
+	}
+
+	btrfs_free_path(path);
+
+	if (be_nice && bytes_deleted > SZ_32M && (ret >= 0 || ret == -EAGAIN)) {
+		unsigned long updates = trans->delayed_ref_updates;
+		int err;
+
+		if (updates) {
+			trans->delayed_ref_updates = 0;
+			err = btrfs_run_delayed_refs(trans, updates * 2);
+			if (err)
+				ret = err;
+		}
+	}
+	return ret;
+}
+
+/*
+ * 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 inode *inode, loff_t from, loff_t len,
+			int front)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct address_space *mapping = inode->i_mapping;
+	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;
+	char *kaddr;
+	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);
+	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_delalloc_reserve_space(inode, &data_reserved,
+					   block_start, blocksize);
+	if (ret)
+		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(BTRFS_I(inode), blocksize);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (!PageUptodate(page)) {
+		ret = btrfs_readpage(NULL, page);
+		lock_page(page);
+		if (page->mapping != mapping) {
+			unlock_page(page);
+			put_page(page);
+			goto again;
+		}
+		if (!PageUptodate(page)) {
+			ret = -EIO;
+			goto out_unlock;
+		}
+	}
+	wait_on_page_writeback(page);
+
+	lock_extent_bits(io_tree, block_start, block_end, &cached_state);
+	set_page_extent_mapped(page);
+
+	ordered = btrfs_lookup_ordered_extent(inode, block_start);
+	if (ordered) {
+		unlock_extent_cached(io_tree, block_start, block_end,
+				     &cached_state);
+		unlock_page(page);
+		put_page(page);
+		btrfs_start_ordered_extent(inode, ordered, 1);
+		btrfs_put_ordered_extent(ordered);
+		goto again;
+	}
+
+	clear_extent_bit(&BTRFS_I(inode)->io_tree, block_start, block_end,
+			  EXTENT_DIRTY | EXTENT_DELALLOC |
+			  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
+			  0, 0, &cached_state);
+
+	ret = btrfs_set_extent_delalloc(inode, block_start, block_end, 0,
+					&cached_state, 0);
+	if (ret) {
+		unlock_extent_cached(io_tree, block_start, block_end,
+				     &cached_state);
+		goto out_unlock;
+	}
+
+	if (offset != blocksize) {
+		if (!len)
+			len = blocksize - offset;
+		kaddr = kmap(page);
+		if (front)
+			memset(kaddr + (block_start - page_offset(page)),
+				0, offset);
+		else
+			memset(kaddr + (block_start - page_offset(page)) +  offset,
+				0, len);
+		flush_dcache_page(page);
+		kunmap(page);
+	}
+	ClearPageChecked(page);
+	set_page_dirty(page);
+	unlock_extent_cached(io_tree, block_start, block_end, &cached_state);
+
+out_unlock:
+	if (ret)
+		btrfs_delalloc_release_space(inode, data_reserved, block_start,
+					     blocksize, true);
+	btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize);
+	unlock_page(page);
+	put_page(page);
+out:
+	extent_changeset_free(data_reserved);
+	return ret;
+}
+
+static int maybe_insert_hole(struct btrfs_root *root, struct inode *inode,
+			     u64 offset, u64 len)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	/*
+	 * Still need to make sure the inode looks like it's been updated so
+	 * that any holes get logged if we fsync.
+	 */
+	if (btrfs_fs_incompat(fs_info, NO_HOLES)) {
+		BTRFS_I(inode)->last_trans = fs_info->generation;
+		BTRFS_I(inode)->last_sub_trans = root->log_transid;
+		BTRFS_I(inode)->last_log_commit = root->last_log_commit;
+		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);
+
+	ret = btrfs_drop_extents(trans, root, inode, offset, offset + len, 1);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		btrfs_end_transaction(trans);
+		return ret;
+	}
+
+	ret = btrfs_insert_file_extent(trans, root, btrfs_ino(BTRFS_I(inode)),
+			offset, 0, 0, len, 0, len, 0, 0, 0);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+	else
+		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 inode *inode, loff_t oldsize, loff_t size)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_map *em = NULL;
+	struct extent_state *cached_state = NULL;
+	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	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;
+
+	while (1) {
+		struct btrfs_ordered_extent *ordered;
+
+		lock_extent_bits(io_tree, hole_start, block_end - 1,
+				 &cached_state);
+		ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), hole_start,
+						     block_end - hole_start);
+		if (!ordered)
+			break;
+		unlock_extent_cached(io_tree, hole_start, block_end - 1,
+				     &cached_state);
+		btrfs_start_ordered_extent(inode, ordered, 1);
+		btrfs_put_ordered_extent(ordered);
+	}
+
+	cur_offset = hole_start;
+	while (1) {
+		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, cur_offset,
+				block_end - cur_offset, 0);
+		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);
+		if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
+			struct extent_map *hole_em;
+			hole_size = last_byte - cur_offset;
+
+			err = maybe_insert_hole(root, inode, cur_offset,
+						hole_size);
+			if (err)
+				break;
+			btrfs_drop_extent_cache(BTRFS_I(inode), cur_offset,
+						cur_offset + hole_size - 1, 0);
+			hole_em = alloc_extent_map();
+			if (!hole_em) {
+				set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
+					&BTRFS_I(inode)->runtime_flags);
+				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->bdev = fs_info->fs_devices->latest_bdev;
+			hole_em->compress_type = BTRFS_COMPRESS_NONE;
+			hole_em->generation = fs_info->generation;
+
+			while (1) {
+				write_lock(&em_tree->lock);
+				err = add_extent_mapping(em_tree, hole_em, 1);
+				write_unlock(&em_tree->lock);
+				if (err != -EEXIST)
+					break;
+				btrfs_drop_extent_cache(BTRFS_I(inode),
+							cur_offset,
+							cur_offset +
+							hole_size - 1, 0);
+			}
+			free_extent_map(hole_em);
+		}
+next:
+		free_extent_map(em);
+		em = NULL;
+		cur_offset = last_byte;
+		if (cur_offset >= block_end)
+			break;
+	}
+	free_extent_map(em);
+	unlock_extent_cached(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_ctime = inode->i_mtime =
+				current_time(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_wait_for_snapshot_creation(root);
+		ret = btrfs_cont_expand(inode, oldsize, newsize);
+		if (ret) {
+			btrfs_end_write_no_snapshotting(root);
+			return ret;
+		}
+
+		trans = btrfs_start_transaction(root, 1);
+		if (IS_ERR(trans)) {
+			btrfs_end_write_no_snapshotting(root);
+			return PTR_ERR(trans);
+		}
+
+		i_size_write(inode, newsize);
+		btrfs_ordered_update_i_size(inode, i_size_read(inode), NULL);
+		pagecache_isize_extended(inode, oldsize, newsize);
+		ret = btrfs_update_inode(trans, root, inode);
+		btrfs_end_write_no_snapshotting(root);
+		btrfs_end_transaction(trans);
+	} else {
+
+		/*
+		 * We're truncating a file that used to have good data down to
+		 * zero. Make sure it gets into the ordered flush list so that
+		 * any new writes get down to disk quickly.
+		 */
+		if (newsize == 0)
+			set_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
+				&BTRFS_I(inode)->runtime_flags);
+
+		truncate_setsize(inode, newsize);
+
+		/* Disable nonlocked read DIO to avoid the end less truncate */
+		btrfs_inode_block_unlocked_dio(BTRFS_I(inode));
+		inode_dio_wait(inode);
+		btrfs_inode_resume_unlocked_dio(BTRFS_I(inode));
+
+		ret = btrfs_truncate(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 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(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(inode, attr);
+		inode_inc_iversion(inode);
+		err = btrfs_dirty_inode(inode);
+
+		if (!err && attr->ia_valid & ATTR_MODE)
+			err = posix_acl_chmod(inode, inode->i_mode);
+	}
+
+	return err;
+}
+
+/*
+ * While truncating the inode pages during eviction, we get the VFS calling
+ * btrfs_invalidatepage() against each page of the inode. This is slow because
+ * the calls to btrfs_invalidatepage() result in a huge amount of calls to
+ * lock_extent_bits() 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_invalidatepage() skip all
+ * those expensive operations on a per page 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 extent_map_tree *map_tree = &BTRFS_I(inode)->extent_tree;
+	struct rb_node *node;
+
+	ASSERT(inode->i_state & I_FREEING);
+	truncate_inode_pages_final(&inode->i_data);
+
+	write_lock(&map_tree->lock);
+	while (!RB_EMPTY_ROOT(&map_tree->map)) {
+		struct extent_map *em;
+
+		node = rb_first(&map_tree->map);
+		em = rb_entry(node, struct extent_map, rb_node);
+		clear_bit(EXTENT_FLAG_PINNED, &em->flags);
+		clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
+		remove_extent_mapping(map_tree, em);
+		free_extent_map(em);
+		if (need_resched()) {
+			write_unlock(&map_tree->lock);
+			cond_resched();
+			write_lock(&map_tree->lock);
+		}
+	}
+	write_unlock(&map_tree->lock);
+
+	/*
+	 * Keep looping until we have no more ranges in the io tree.
+	 * We can have ongoing bios started by readpages (called from 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_bits(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_invalidatepage, case 2)
+		 *
+		 * Note, end is the bytenr of last byte, so we need + 1 here.
+		 */
+		if (state_flags & EXTENT_DELALLOC)
+			btrfs_qgroup_free_data(inode, NULL, start, end - start + 1);
+
+		clear_extent_bit(io_tree, start, end,
+				 EXTENT_LOCKED | EXTENT_DIRTY |
+				 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
+				 EXTENT_DEFRAG, 1, 1, &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,
+							u64 min_size)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
+	int failures = 0;
+
+	for (;;) {
+		struct btrfs_trans_handle *trans;
+		int ret;
+
+		ret = btrfs_block_rsv_refill(root, rsv, min_size,
+					     BTRFS_RESERVE_FLUSH_LIMIT);
+
+		if (ret && ++failures > 2) {
+			btrfs_warn(fs_info,
+				   "could not allocate space for a delete; will truncate on mount");
+			return ERR_PTR(-ENOSPC);
+		}
+
+		trans = btrfs_join_transaction(root);
+		if (IS_ERR(trans) || !ret)
+			return trans;
+
+		/*
+		 * Try to steal from the global reserve if there is space for
+		 * it.
+		 */
+		if (!btrfs_check_space_for_delayed_refs(trans, fs_info) &&
+		    !btrfs_block_rsv_migrate(global_rsv, rsv, min_size, 0))
+			return trans;
+
+		/* If not, commit and try again. */
+		ret = btrfs_commit_transaction(trans);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+}
+
+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;
+	u64 min_size;
+	int ret;
+
+	trace_btrfs_inode_evict(inode);
+
+	if (!root) {
+		clear_inode(inode);
+		return;
+	}
+
+	min_size = btrfs_calc_trunc_metadata_size(fs_info, 1);
+
+	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 no_delete;
+
+	if (is_bad_inode(inode))
+		goto no_delete;
+	/* do we really want it for ->i_nlink > 0 and zero btrfs_root_refs? */
+	if (!special_file(inode->i_mode))
+		btrfs_wait_ordered_range(inode, 0, (u64)-1);
+
+	btrfs_free_io_failure_record(BTRFS_I(inode), 0, (u64)-1);
+
+	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
+		goto no_delete;
+
+	if (inode->i_nlink > 0) {
+		BUG_ON(btrfs_root_refs(&root->root_item) != 0 &&
+		       root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID);
+		goto no_delete;
+	}
+
+	ret = btrfs_commit_inode_delayed_inode(BTRFS_I(inode));
+	if (ret)
+		goto no_delete;
+
+	rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
+	if (!rsv)
+		goto no_delete;
+	rsv->size = min_size;
+	rsv->failfast = 1;
+
+	btrfs_i_size_write(BTRFS_I(inode), 0);
+
+	while (1) {
+		trans = evict_refill_and_join(root, rsv, min_size);
+		if (IS_ERR(trans))
+			goto free_rsv;
+
+		trans->block_rsv = rsv;
+
+		ret = btrfs_truncate_inode_items(trans, root, inode, 0, 0);
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		btrfs_end_transaction(trans);
+		btrfs_btree_balance_dirty(fs_info);
+		if (ret && ret != -ENOSPC && ret != -EAGAIN)
+			goto free_rsv;
+		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, min_size);
+	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);
+	}
+
+	if (!(root == fs_info->tree_root ||
+	      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID))
+		btrfs_return_ino(root, btrfs_ino(BTRFS_I(inode)));
+
+free_rsv:
+	btrfs_free_block_rsv(fs_info, rsv);
+no_delete:
+	/*
+	 * 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));
+	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 inode *dir, struct dentry *dentry,
+			       struct btrfs_key *location, u8 *type)
+{
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	struct btrfs_dir_item *di;
+	struct btrfs_path *path;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	int ret = 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	di = btrfs_lookup_dir_item(NULL, root, path, btrfs_ino(BTRFS_I(dir)),
+			name, namelen, 0);
+	if (!di) {
+		ret = -ENOENT;
+		goto out;
+	}
+	if (IS_ERR(di)) {
+		ret = PTR_ERR(di);
+		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__, name, btrfs_ino(BTRFS_I(dir)),
+			   location->objectid, location->type, location->offset);
+	}
+	if (!ret)
+		*type = btrfs_dir_type(path->nodes[0], di);
+out:
+	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 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;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	err = -ENOENT;
+	key.objectid = BTRFS_I(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(BTRFS_I(dir)) ||
+	    btrfs_root_ref_name_len(leaf, ref) != dentry->d_name.len)
+		goto out;
+
+	ret = memcmp_extent_buffer(leaf, dentry->d_name.name,
+				   (unsigned long)(ref + 1),
+				   dentry->d_name.len);
+	if (ret)
+		goto out;
+
+	btrfs_release_path(path);
+
+	new_root = btrfs_read_fs_root_no_name(fs_info, location);
+	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);
+	return err;
+}
+
+static void inode_tree_add(struct inode *inode)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_inode *entry;
+	struct rb_node **p;
+	struct rb_node *parent;
+	struct rb_node *new = &BTRFS_I(inode)->rb_node;
+	u64 ino = btrfs_ino(BTRFS_I(inode));
+
+	if (inode_unhashed(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 inode *inode)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int empty = 0;
+
+	spin_lock(&root->inode_lock);
+	if (!RB_EMPTY_NODE(&BTRFS_I(inode)->rb_node)) {
+		rb_erase(&BTRFS_I(inode)->rb_node, &root->inode_tree);
+		RB_CLEAR_NODE(&BTRFS_I(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->location->objectid;
+	memcpy(&BTRFS_I(inode)->location, args->location,
+	       sizeof(*args->location));
+	BTRFS_I(inode)->root = args->root;
+	return 0;
+}
+
+static int btrfs_find_actor(struct inode *inode, void *opaque)
+{
+	struct btrfs_iget_args *args = opaque;
+	return args->location->objectid == BTRFS_I(inode)->location.objectid &&
+		args->root == BTRFS_I(inode)->root;
+}
+
+static struct inode *btrfs_iget_locked(struct super_block *s,
+				       struct btrfs_key *location,
+				       struct btrfs_root *root)
+{
+	struct inode *inode;
+	struct btrfs_iget_args args;
+	unsigned long hashval = btrfs_inode_hash(location->objectid, root);
+
+	args.location = location;
+	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 location and corresponding root.
+ * Returns in *is_new if the inode was read from disk
+ */
+struct inode *btrfs_iget_path(struct super_block *s, struct btrfs_key *location,
+			      struct btrfs_root *root, int *new,
+			      struct btrfs_path *path)
+{
+	struct inode *inode;
+
+	inode = btrfs_iget_locked(s, location, 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(inode);
+			unlock_new_inode(inode);
+			if (new)
+				*new = 1;
+		} 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, struct btrfs_key *location,
+			 struct btrfs_root *root, int *new)
+{
+	return btrfs_iget_path(s, location, root, new, NULL);
+}
+
+static struct inode *new_simple_dir(struct super_block *s,
+				    struct btrfs_key *key,
+				    struct btrfs_root *root)
+{
+	struct inode *inode = new_inode(s);
+
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	BTRFS_I(inode)->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;
+	inode->i_op = &btrfs_dir_ro_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 = current_time(inode);
+	inode->i_atime = inode->i_mtime;
+	inode->i_ctime = inode->i_mtime;
+	BTRFS_I(inode)->i_otime = inode->i_mtime;
+
+	return inode;
+}
+
+static inline u8 btrfs_inode_type(struct inode *inode)
+{
+	return btrfs_type_by_mode[(inode->i_mode & S_IFMT) >> S_SHIFT];
+}
+
+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 index;
+	int ret = 0;
+
+	if (dentry->d_name.len > BTRFS_NAME_LEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	ret = btrfs_inode_by_name(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, root, NULL);
+		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;
+	}
+
+	index = srcu_read_lock(&fs_info->subvol_srcu);
+	ret = fixup_tree_root_location(fs_info, dir, dentry,
+				       &location, &sub_root);
+	if (ret < 0) {
+		if (ret != -ENOENT)
+			inode = ERR_PTR(ret);
+		else
+			inode = new_simple_dir(dir->i_sb, &location, sub_root);
+	} else {
+		inode = btrfs_iget(dir->i_sb, &location, sub_root, NULL);
+	}
+	srcu_read_unlock(&fs_info->subvol_srcu, index);
+
+	if (!IS_ERR(inode) && root != sub_root) {
+		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;
+
+	inode = btrfs_lookup_dentry(dir, dentry);
+	if (IS_ERR(inode)) {
+		if (PTR_ERR(inode) == -ENOENT)
+			inode = NULL;
+		else
+			return ERR_CAST(inode);
+	}
+
+	return d_splice_alias(inode, dentry);
+}
+
+unsigned char btrfs_filetype_table[] = {
+	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
+};
+
+/*
+ * 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;
+
+	private = kzalloc(sizeof(struct btrfs_file_private), GFP_KERNEL);
+	if (!private)
+		return -ENOMEM;
+	private->filldir_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!private->filldir_buf) {
+		kfree(private);
+		return -ENOMEM;
+	}
+	file->private_data = private;
+	return 0;
+}
+
+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;
+	struct list_head ins_list;
+	struct list_head del_list;
+	int ret;
+	struct extent_buffer *leaf;
+	int slot;
+	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;
+
+	INIT_LIST_HEAD(&ins_list);
+	INIT_LIST_HEAD(&del_list);
+	put = btrfs_readdir_get_delayed_items(inode, &ins_list, &del_list);
+
+again:
+	key.type = BTRFS_DIR_INDEX_KEY;
+	key.offset = ctx->pos;
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto err;
+
+	while (1) {
+		struct dir_entry *entry;
+
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto err;
+			else if (ret > 0)
+				break;
+			continue;
+		}
+
+		btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+		if (found_key.objectid != key.objectid)
+			break;
+		if (found_key.type != BTRFS_DIR_INDEX_KEY)
+			break;
+		if (found_key.offset < ctx->pos)
+			goto next;
+		if (btrfs_should_delete_dir_index(&del_list, found_key.offset))
+			goto next;
+		di = btrfs_item_ptr(leaf, slot, 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;
+		}
+
+		entry = addr;
+		put_unaligned(name_len, &entry->name_len);
+		name_ptr = (char *)(entry + 1);
+		read_extent_buffer(leaf, name_ptr, (unsigned long)(di + 1),
+				   name_len);
+		put_unaligned(btrfs_filetype_table[btrfs_dir_type(leaf, di)],
+				&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;
+next:
+		path->slots[0]++;
+	}
+	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 inode *inode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	if (test_bit(BTRFS_INODE_DUMMY, &BTRFS_I(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) {
+		/* 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 (BTRFS_I(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, struct timespec64 *now,
+			     int flags)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	bool dirty = flags & ~S_VERSION;
+
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+
+	if (flags & S_VERSION)
+		dirty |= inode_maybe_inc_iversion(inode, dirty);
+	if (flags & S_CTIME)
+		inode->i_ctime = *now;
+	if (flags & S_MTIME)
+		inode->i_mtime = *now;
+	if (flags & S_ATIME)
+		inode->i_atime = *now;
+	return dirty ? btrfs_dirty_inode(inode) : 0;
+}
+
+/*
+ * find the highest existing sequence number in a directory
+ * and then set the in-memory index_cnt variable to reflect
+ * free sequence numbers
+ */
+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;
+
+	/*
+	 * MAGIC NUMBER EXPLANATION:
+	 * since we search a directory based on f_pos we have to start at 2
+	 * since '.' and '..' have f_pos of 0 and 1 respectively, so everybody
+	 * else has to start at 2
+	 */
+	if (path->slots[0] == 0) {
+		inode->index_cnt = 2;
+		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 = 2;
+		goto out;
+	}
+
+	inode->index_cnt = found_key.offset + 1;
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * 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.location = &BTRFS_I(inode)->location;
+	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);
+}
+
+/*
+ * Inherit flags from the parent inode.
+ *
+ * Currently only the compression flags and the cow flags are inherited.
+ */
+static void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
+{
+	unsigned int flags;
+
+	if (!dir)
+		return;
+
+	flags = BTRFS_I(dir)->flags;
+
+	if (flags & BTRFS_INODE_NOCOMPRESS) {
+		BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
+		BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
+	} else if (flags & BTRFS_INODE_COMPRESS) {
+		BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
+		BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
+	}
+
+	if (flags & BTRFS_INODE_NODATACOW) {
+		BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
+		if (S_ISREG(inode->i_mode))
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
+	}
+
+	btrfs_sync_inode_flags_to_i_flags(inode);
+}
+
+static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
+				     struct btrfs_root *root,
+				     struct inode *dir,
+				     const char *name, int name_len,
+				     u64 ref_objectid, u64 objectid,
+				     umode_t mode, u64 *index)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct inode *inode;
+	struct btrfs_inode_item *inode_item;
+	struct btrfs_key *location;
+	struct btrfs_path *path;
+	struct btrfs_inode_ref *ref;
+	struct btrfs_key key[2];
+	u32 sizes[2];
+	int nitems = name ? 2 : 1;
+	unsigned long ptr;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return ERR_PTR(-ENOMEM);
+
+	inode = new_inode(fs_info->sb);
+	if (!inode) {
+		btrfs_free_path(path);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/*
+	 * O_TMPFILE, set link count to 0, so that after this point,
+	 * we fill in an inode item with the correct link count.
+	 */
+	if (!name)
+		set_nlink(inode, 0);
+
+	/*
+	 * we have to initialize this early, so we can reclaim the inode
+	 * number if we fail afterwards in this function.
+	 */
+	inode->i_ino = objectid;
+
+	if (dir && name) {
+		trace_btrfs_inode_request(dir);
+
+		ret = btrfs_set_inode_index(BTRFS_I(dir), index);
+		if (ret) {
+			btrfs_free_path(path);
+			iput(inode);
+			return ERR_PTR(ret);
+		}
+	} else if (dir) {
+		*index = 0;
+	}
+	/*
+	 * index_cnt is ignored for everything but a dir,
+	 * btrfs_set_inode_index_count has an explanation for the magic
+	 * number
+	 */
+	BTRFS_I(inode)->index_cnt = 2;
+	BTRFS_I(inode)->dir_index = *index;
+	BTRFS_I(inode)->root = root;
+	BTRFS_I(inode)->generation = trans->transid;
+	inode->i_generation = BTRFS_I(inode)->generation;
+
+	/*
+	 * 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.
+	 */
+	set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(inode)->runtime_flags);
+
+	key[0].objectid = objectid;
+	key[0].type = BTRFS_INODE_ITEM_KEY;
+	key[0].offset = 0;
+
+	sizes[0] = sizeof(struct btrfs_inode_item);
+
+	if (name) {
+		/*
+		 * 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;
+		key[1].offset = ref_objectid;
+
+		sizes[1] = name_len + sizeof(*ref);
+	}
+
+	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) {
+		iput(inode);
+		goto fail;
+	}
+
+	path->leave_spinning = 1;
+	ret = btrfs_insert_empty_items(trans, root, path, key, sizes, nitems);
+	if (ret != 0)
+		goto fail_unlock;
+
+	inode_init_owner(inode, dir, mode);
+	inode_set_bytes(inode, 0);
+
+	inode->i_mtime = current_time(inode);
+	inode->i_atime = inode->i_mtime;
+	inode->i_ctime = inode->i_mtime;
+	BTRFS_I(inode)->i_otime = inode->i_mtime;
+
+	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 (name) {
+		ref = btrfs_item_ptr(path->nodes[0], path->slots[0] + 1,
+				     struct btrfs_inode_ref);
+		btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
+		btrfs_set_inode_ref_index(path->nodes[0], ref, *index);
+		ptr = (unsigned long)(ref + 1);
+		write_extent_buffer(path->nodes[0], name, ptr, name_len);
+	}
+
+	btrfs_mark_buffer_dirty(path->nodes[0]);
+	btrfs_free_path(path);
+
+	btrfs_inherit_iflags(inode, dir);
+
+	if (S_ISREG(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;
+	}
+
+	inode_tree_add(inode);
+
+	trace_btrfs_inode_new(inode);
+	btrfs_set_inode_last_trans(trans, inode);
+
+	btrfs_update_root_times(trans, root);
+
+	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);
+
+	return inode;
+
+fail_unlock:
+	discard_new_inode(inode);
+fail:
+	if (dir && name)
+		BTRFS_I(dir)->index_cnt--;
+	btrfs_free_path(path);
+	return ERR_PTR(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 char *name, int name_len, 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, name_len);
+	} else if (add_backref) {
+		ret = btrfs_insert_inode_ref(trans, root, name, name_len, ino,
+					     parent_ino, index);
+	}
+
+	/* Nothing to clean up yet */
+	if (ret)
+		return ret;
+
+	ret = btrfs_insert_dir_item(trans, root, name, name_len,
+				    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)) {
+		struct timespec64 now = current_time(&parent_inode->vfs_inode);
+
+		parent_inode->vfs_inode.i_mtime = now;
+		parent_inode->vfs_inode.i_ctime = now;
+	}
+	ret = btrfs_update_inode(trans, root, &parent_inode->vfs_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, name_len);
+		if (err)
+			btrfs_abort_transaction(trans, err);
+	} else if (add_backref) {
+		u64 local_index;
+		int err;
+
+		err = btrfs_del_inode_ref(trans, root, name, name_len,
+					  ino, parent_ino, &local_index);
+		if (err)
+			btrfs_abort_transaction(trans, err);
+	}
+
+	/* Return the original error code */
+	return ret;
+}
+
+static int btrfs_add_nondir(struct btrfs_trans_handle *trans,
+			    struct btrfs_inode *dir, struct dentry *dentry,
+			    struct btrfs_inode *inode, int backref, u64 index)
+{
+	int err = btrfs_add_link(trans, dir, inode,
+				 dentry->d_name.name, dentry->d_name.len,
+				 backref, index);
+	if (err > 0)
+		err = -EEXIST;
+	return err;
+}
+
+static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
+			umode_t mode, dev_t rdev)
+{
+	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 = NULL;
+	int err;
+	u64 objectid;
+	u64 index = 0;
+
+	/*
+	 * 2 for inode item and ref
+	 * 2 for dir items
+	 * 1 for xattr if selinux is on
+	 */
+	trans = btrfs_start_transaction(root, 5);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	err = btrfs_find_free_ino(root, &objectid);
+	if (err)
+		goto out_unlock;
+
+	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
+			dentry->d_name.len, btrfs_ino(BTRFS_I(dir)), objectid,
+			mode, &index);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		inode = NULL;
+		goto out_unlock;
+	}
+
+	/*
+	* If the active LSM wants to access the inode during
+	* d_instantiate it needs these. Smack checks to see
+	* if the filesystem supports xattrs by looking at the
+	* ops vector.
+	*/
+	inode->i_op = &btrfs_special_inode_operations;
+	init_special_inode(inode, inode->i_mode, rdev);
+
+	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
+	if (err)
+		goto out_unlock;
+
+	err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
+			0, index);
+	if (err)
+		goto out_unlock;
+
+	btrfs_update_inode(trans, root, inode);
+	d_instantiate_new(dentry, inode);
+
+out_unlock:
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+	if (err && inode) {
+		inode_dec_link_count(inode);
+		discard_new_inode(inode);
+	}
+	return err;
+}
+
+static int btrfs_create(struct inode *dir, struct dentry *dentry,
+			umode_t mode, bool excl)
+{
+	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 = NULL;
+	int err;
+	u64 objectid;
+	u64 index = 0;
+
+	/*
+	 * 2 for inode item and ref
+	 * 2 for dir items
+	 * 1 for xattr if selinux is on
+	 */
+	trans = btrfs_start_transaction(root, 5);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	err = btrfs_find_free_ino(root, &objectid);
+	if (err)
+		goto out_unlock;
+
+	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
+			dentry->d_name.len, btrfs_ino(BTRFS_I(dir)), objectid,
+			mode, &index);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		inode = NULL;
+		goto out_unlock;
+	}
+	/*
+	* If the active LSM wants to access the inode during
+	* d_instantiate it needs these. Smack checks to see
+	* if the filesystem supports xattrs by looking at the
+	* ops vector.
+	*/
+	inode->i_fop = &btrfs_file_operations;
+	inode->i_op = &btrfs_file_inode_operations;
+	inode->i_mapping->a_ops = &btrfs_aops;
+
+	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
+	if (err)
+		goto out_unlock;
+
+	err = btrfs_update_inode(trans, root, inode);
+	if (err)
+		goto out_unlock;
+
+	err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
+			0, index);
+	if (err)
+		goto out_unlock;
+
+	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
+	d_instantiate_new(dentry, inode);
+
+out_unlock:
+	btrfs_end_transaction(trans);
+	if (err && inode) {
+		inode_dec_link_count(inode);
+		discard_new_inode(inode);
+	}
+	btrfs_btree_balance_dirty(fs_info);
+	return err;
+}
+
+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);
+	u64 index;
+	int err;
+	int drop_inode = 0;
+
+	/* do not allow sys_link's with other subvols of the same device */
+	if (root->objectid != BTRFS_I(inode)->root->objectid)
+		return -EXDEV;
+
+	if (inode->i_nlink >= BTRFS_LINK_MAX)
+		return -EMLINK;
+
+	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->i_ctime = current_time(inode);
+	ihold(inode);
+	set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
+
+	err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
+			1, index);
+
+	if (err) {
+		drop_inode = 1;
+	} else {
+		struct dentry *parent = dentry->d_parent;
+		int ret;
+
+		err = btrfs_update_inode(trans, root, 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;
+		}
+		BTRFS_I(inode)->last_link_trans = trans->transid;
+		d_instantiate(dentry, inode);
+		ret = btrfs_log_new_name(trans, BTRFS_I(inode), NULL, parent,
+					 true, NULL);
+		if (ret == BTRFS_NEED_TRANS_COMMIT) {
+			err = btrfs_commit_transaction(trans);
+			trans = NULL;
+		}
+	}
+
+fail:
+	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 inode *dir, struct dentry *dentry, umode_t mode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
+	struct inode *inode = NULL;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	int err = 0;
+	int drop_on_err = 0;
+	u64 objectid = 0;
+	u64 index = 0;
+
+	/*
+	 * 2 items for inode and ref
+	 * 2 items for dir items
+	 * 1 for xattr if selinux is on
+	 */
+	trans = btrfs_start_transaction(root, 5);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	err = btrfs_find_free_ino(root, &objectid);
+	if (err)
+		goto out_fail;
+
+	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
+			dentry->d_name.len, btrfs_ino(BTRFS_I(dir)), objectid,
+			S_IFDIR | mode, &index);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		inode = NULL;
+		goto out_fail;
+	}
+
+	drop_on_err = 1;
+	/* these must be set before we unlock the inode */
+	inode->i_op = &btrfs_dir_inode_operations;
+	inode->i_fop = &btrfs_dir_file_operations;
+
+	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
+	if (err)
+		goto out_fail;
+
+	btrfs_i_size_write(BTRFS_I(inode), 0);
+	err = btrfs_update_inode(trans, root, inode);
+	if (err)
+		goto out_fail;
+
+	err = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode),
+			dentry->d_name.name,
+			dentry->d_name.len, 0, index);
+	if (err)
+		goto out_fail;
+
+	d_instantiate_new(dentry, inode);
+	drop_on_err = 0;
+
+out_fail:
+	btrfs_end_transaction(trans);
+	if (err && inode) {
+		inode_dec_link_count(inode);
+		discard_new_inode(inode);
+	}
+	btrfs_btree_balance_dirty(fs_info);
+	return err;
+}
+
+static noinline int uncompress_inline(struct btrfs_path *path,
+				      struct page *page,
+				      size_t pg_offset, u64 extent_offset,
+				      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;
+
+	WARN_ON(pg_offset != 0);
+	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,
+					btrfs_item_nr(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,
+			       extent_offset, 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 + pg_offset < PAGE_SIZE) {
+		char *map = kmap(page);
+		memset(map + pg_offset + max_size, 0, PAGE_SIZE - max_size - pg_offset);
+		kunmap(page);
+	}
+	kfree(tmp);
+	return ret;
+}
+
+/*
+ * a bit scary, this does extent mapping from logical file offset to the disk.
+ * the ugly parts come from merging extents from the disk with the in-ram
+ * representation.  This gets more complex because of the data=ordered code,
+ * where the in-ram extents might be locked pending data=ordered completion.
+ *
+ * This also copies inline extents directly into the page.
+ */
+struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
+		struct page *page,
+	    size_t pg_offset, u64 start, u64 len,
+		int create)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	int ret;
+	int err = 0;
+	u64 extent_start = 0;
+	u64 extent_end = 0;
+	u64 objectid = btrfs_ino(inode);
+	u32 found_type;
+	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;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	const bool new_inline = !page || create;
+
+	read_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, start, len);
+	if (em)
+		em->bdev = fs_info->fs_devices->latest_bdev;
+	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) {
+		err = -ENOMEM;
+		goto out;
+	}
+	em->bdev = fs_info->fs_devices->latest_bdev;
+	em->start = EXTENT_MAP_HOLE;
+	em->orig_start = EXTENT_MAP_HOLE;
+	em->len = (u64)-1;
+	em->block_len = (u64)-1;
+
+	if (!path) {
+		path = btrfs_alloc_path();
+		if (!path) {
+			err = -ENOMEM;
+			goto out;
+		}
+		/*
+		 * Chances are we'll be called again, so go ahead and do
+		 * readahead
+		 */
+		path->reada = READA_FORWARD;
+	}
+
+	ret = btrfs_lookup_file_extent(NULL, root, path, objectid, start, 0);
+	if (ret < 0) {
+		err = ret;
+		goto out;
+	}
+
+	if (ret != 0) {
+		if (path->slots[0] == 0)
+			goto not_found;
+		path->slots[0]--;
+	}
+
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0],
+			      struct btrfs_file_extent_item);
+	/* are we inside the extent that was found? */
+	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+	found_type = found_key.type;
+	if (found_key.objectid != objectid ||
+	    found_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;
+	}
+
+	found_type = btrfs_file_extent_type(leaf, item);
+	extent_start = found_key.offset;
+	if (found_type == BTRFS_FILE_EXTENT_REG ||
+	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		/* Only regular file could have regular/prealloc extent */
+		if (!S_ISREG(inode->vfs_inode.i_mode)) {
+			err = -EUCLEAN;
+			btrfs_crit(fs_info,
+		"regular/prealloc extent found for non-regular inode %llu",
+				   btrfs_ino(inode));
+			goto out;
+		}
+		extent_end = extent_start +
+		       btrfs_file_extent_num_bytes(leaf, item);
+
+		trace_btrfs_get_extent_show_fi_regular(inode, leaf, item,
+						       extent_start);
+	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+		size_t size;
+
+		size = btrfs_file_extent_ram_bytes(leaf, item);
+		extent_end = ALIGN(extent_start + size,
+				   fs_info->sectorsize);
+
+		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) {
+				err = ret;
+				goto out;
+			}
+			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;
+		em->start = start;
+		em->orig_start = start;
+		em->len = found_key.offset - start;
+		goto not_found_em;
+	}
+
+	btrfs_extent_item_to_extent_map(inode, path, item,
+			new_inline, em);
+
+	if (found_type == BTRFS_FILE_EXTENT_REG ||
+	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		goto insert;
+	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+		unsigned long ptr;
+		char *map;
+		size_t size;
+		size_t extent_offset;
+		size_t copy_size;
+
+		if (new_inline)
+			goto out;
+
+		size = btrfs_file_extent_ram_bytes(leaf, item);
+		extent_offset = page_offset(page) + pg_offset - extent_start;
+		copy_size = min_t(u64, PAGE_SIZE - pg_offset,
+				  size - extent_offset);
+		em->start = extent_start + extent_offset;
+		em->len = ALIGN(copy_size, fs_info->sectorsize);
+		em->orig_block_len = em->len;
+		em->orig_start = em->start;
+		ptr = btrfs_file_extent_inline_start(item) + extent_offset;
+		if (!PageUptodate(page)) {
+			if (btrfs_file_extent_compression(leaf, item) !=
+			    BTRFS_COMPRESS_NONE) {
+				ret = uncompress_inline(path, page, pg_offset,
+							extent_offset, item);
+				if (ret) {
+					err = ret;
+					goto out;
+				}
+			} else {
+				map = kmap(page);
+				read_extent_buffer(leaf, map + pg_offset, ptr,
+						   copy_size);
+				if (pg_offset + copy_size < PAGE_SIZE) {
+					memset(map + pg_offset + copy_size, 0,
+					       PAGE_SIZE - pg_offset -
+					       copy_size);
+				}
+				kunmap(page);
+			}
+			flush_dcache_page(page);
+		}
+		set_extent_uptodate(io_tree, em->start,
+				    extent_map_end(em) - 1, NULL, GFP_NOFS);
+		goto insert;
+	}
+not_found:
+	em->start = start;
+	em->orig_start = start;
+	em->len = len;
+not_found_em:
+	em->block_start = EXTENT_MAP_HOLE;
+insert:
+	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);
+		err = -EIO;
+		goto out;
+	}
+
+	err = 0;
+	write_lock(&em_tree->lock);
+	err = btrfs_add_extent_mapping(fs_info, em_tree, &em, start, len);
+	write_unlock(&em_tree->lock);
+out:
+
+	trace_btrfs_get_extent(root, inode, em);
+
+	btrfs_free_path(path);
+	if (err) {
+		free_extent_map(em);
+		return ERR_PTR(err);
+	}
+	BUG_ON(!em); /* Error is always set */
+	return em;
+}
+
+struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
+		struct page *page,
+		size_t pg_offset, u64 start, u64 len,
+		int create)
+{
+	struct extent_map *em;
+	struct extent_map *hole_em = NULL;
+	u64 range_start = start;
+	u64 end;
+	u64 found;
+	u64 found_end;
+	int err = 0;
+
+	em = btrfs_get_extent(inode, page, pg_offset, start, len, create);
+	if (IS_ERR(em))
+		return em;
+	/*
+	 * If our em maps to:
+	 * - a hole or
+	 * - a pre-alloc extent,
+	 * there might actually be delalloc bytes behind it.
+	 */
+	if (em->block_start != EXTENT_MAP_HOLE &&
+	    !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+		return em;
+	else
+		hole_em = em;
+
+	/* check to see if we've wrapped (len == -1 or similar) */
+	end = start + len;
+	if (end < start)
+		end = (u64)-1;
+	else
+		end -= 1;
+
+	em = NULL;
+
+	/* ok, we didn't find anything, lets look for delalloc */
+	found = count_range_bits(&inode->io_tree, &range_start,
+				 end, len, EXTENT_DELALLOC, 1);
+	found_end = range_start + found;
+	if (found_end < range_start)
+		found_end = (u64)-1;
+
+	/*
+	 * we didn't find anything useful, return
+	 * the original results from get_extent()
+	 */
+	if (range_start > end || found_end <= start) {
+		em = hole_em;
+		hole_em = NULL;
+		goto out;
+	}
+
+	/* adjust the range_start to make sure it doesn't
+	 * go backwards from the start they passed in
+	 */
+	range_start = max(start, range_start);
+	found = found_end - range_start;
+
+	if (found > 0) {
+		u64 hole_start = start;
+		u64 hole_len = len;
+
+		em = alloc_extent_map();
+		if (!em) {
+			err = -ENOMEM;
+			goto out;
+		}
+		/*
+		 * when btrfs_get_extent can't find anything it
+		 * returns one huge hole
+		 *
+		 * make sure what it found really fits our range, and
+		 * adjust to make sure it is based on the start from
+		 * the caller
+		 */
+		if (hole_em) {
+			u64 calc_end = extent_map_end(hole_em);
+
+			if (calc_end <= start || (hole_em->start > end)) {
+				free_extent_map(hole_em);
+				hole_em = NULL;
+			} else {
+				hole_start = max(hole_em->start, start);
+				hole_len = calc_end - hole_start;
+			}
+		}
+		em->bdev = NULL;
+		if (hole_em && range_start > hole_start) {
+			/* our hole starts before our delalloc, so we
+			 * have to return just the parts of the hole
+			 * that go until  the delalloc starts
+			 */
+			em->len = min(hole_len,
+				      range_start - hole_start);
+			em->start = hole_start;
+			em->orig_start = hole_start;
+			/*
+			 * don't adjust block start at all,
+			 * it is fixed at EXTENT_MAP_HOLE
+			 */
+			em->block_start = hole_em->block_start;
+			em->block_len = hole_len;
+			if (test_bit(EXTENT_FLAG_PREALLOC, &hole_em->flags))
+				set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
+		} else {
+			em->start = range_start;
+			em->len = found;
+			em->orig_start = range_start;
+			em->block_start = EXTENT_MAP_DELALLOC;
+			em->block_len = found;
+		}
+	} else {
+		return hole_em;
+	}
+out:
+
+	free_extent_map(hole_em);
+	if (err) {
+		free_extent_map(em);
+		return ERR_PTR(err);
+	}
+	return em;
+}
+
+static struct extent_map *btrfs_create_dio_extent(struct inode *inode,
+						  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;
+	int ret;
+
+	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;
+	}
+	ret = btrfs_add_ordered_extent_dio(inode, start, block_start,
+					   len, block_len, type);
+	if (ret) {
+		if (em) {
+			free_extent_map(em);
+			btrfs_drop_extent_cache(BTRFS_I(inode), start,
+						start + len - 1, 0);
+		}
+		em = ERR_PTR(ret);
+	}
+ out:
+
+	return em;
+}
+
+static struct extent_map *btrfs_new_extent_direct(struct inode *inode,
+						  u64 start, u64 len)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct extent_map *em;
+	struct btrfs_key ins;
+	u64 alloc_hint;
+	int ret;
+
+	alloc_hint = get_extent_allocation_hint(inode, start, len);
+	ret = btrfs_reserve_extent(root, len, len, fs_info->sectorsize,
+				   0, alloc_hint, &ins, 1, 1);
+	if (ret)
+		return ERR_PTR(ret);
+
+	em = btrfs_create_dio_extent(inode, 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;
+}
+
+/*
+ * returns 1 when the nocow is safe, < 1 on error, 0 if the
+ * block must be cow'd
+ */
+noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
+			      u64 *orig_start, u64 *orig_block_len,
+			      u64 *ram_bytes)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	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;
+	u64 disk_bytenr;
+	u64 backref_offset;
+	u64 extent_end;
+	u64 num_bytes;
+	int slot;
+	int found_type;
+	bool nocow = (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_lookup_file_extent(NULL, root, path,
+			btrfs_ino(BTRFS_I(inode)), offset, 0);
+	if (ret < 0)
+		goto out;
+
+	slot = path->slots[0];
+	if (ret == 1) {
+		if (slot == 0) {
+			/* can't find the item, must cow */
+			ret = 0;
+			goto out;
+		}
+		slot--;
+	}
+	ret = 0;
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &key, slot);
+	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;
+	}
+
+	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+	found_type = btrfs_file_extent_type(leaf, fi);
+	if (found_type != BTRFS_FILE_EXTENT_REG &&
+	    found_type != BTRFS_FILE_EXTENT_PREALLOC) {
+		/* not a regular extent, must cow */
+		goto out;
+	}
+
+	if (!nocow && found_type == BTRFS_FILE_EXTENT_REG)
+		goto out;
+
+	extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
+	if (extent_end <= offset)
+		goto out;
+
+	disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+	if (disk_bytenr == 0)
+		goto out;
+
+	if (btrfs_file_extent_compression(leaf, fi) ||
+	    btrfs_file_extent_encryption(leaf, fi) ||
+	    btrfs_file_extent_other_encoding(leaf, fi))
+		goto out;
+
+	/*
+	 * Do the same check as in btrfs_cross_ref_exist but without the
+	 * unnecessary search.
+	 */
+	if (btrfs_file_extent_generation(leaf, fi) <=
+	    btrfs_root_last_snapshot(&root->root_item))
+		goto out;
+
+	backref_offset = btrfs_file_extent_offset(leaf, fi);
+
+	if (orig_start) {
+		*orig_start = key.offset - backref_offset;
+		*orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
+		*ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
+	}
+
+	if (btrfs_extent_readonly(fs_info, disk_bytenr))
+		goto out;
+
+	num_bytes = min(offset + *len, extent_end) - offset;
+	if (!nocow && found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		u64 range_end;
+
+		range_end = round_up(offset + 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;
+		}
+	}
+
+	btrfs_release_path(path);
+
+	/*
+	 * look for other files referencing this extent, if we
+	 * find any we must cow
+	 */
+
+	ret = btrfs_cross_ref_exist(root, btrfs_ino(BTRFS_I(inode)),
+				    key.offset - backref_offset, disk_bytenr);
+	if (ret) {
+		ret = 0;
+		goto out;
+	}
+
+	/*
+	 * adjust disk_bytenr and num_bytes to cover just the bytes
+	 * in this extent we are about to write.  If there
+	 * are any csums in that range we have to cow in order
+	 * to keep the csums correct
+	 */
+	disk_bytenr += backref_offset;
+	disk_bytenr += offset - key.offset;
+	if (csum_exist_in_range(fs_info, disk_bytenr, num_bytes))
+		goto out;
+	/*
+	 * all of the above have passed, it is safe to overwrite this extent
+	 * without cow
+	 */
+	*len = 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, int writing)
+{
+	struct btrfs_ordered_extent *ordered;
+	int ret = 0;
+
+	while (1) {
+		lock_extent_bits(&BTRFS_I(inode)->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_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
+				     cached_state);
+
+		if (ordered) {
+			/*
+			 * 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(inode, ordered, 1);
+			else
+				ret = -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 readpages() (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 readpages() wait for that
+			 * ordered extent to complete while holding a lock on
+			 * that page.
+			 */
+			ret = -ENOTBLK;
+		}
+
+		if (ret)
+			break;
+
+		cond_resched();
+	}
+
+	return ret;
+}
+
+/* The callers of this must take lock_extent() */
+static struct extent_map *create_io_em(struct 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_tree *em_tree;
+	struct extent_map *em;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int ret;
+
+	ASSERT(type == BTRFS_ORDERED_PREALLOC ||
+	       type == BTRFS_ORDERED_COMPRESSED ||
+	       type == BTRFS_ORDERED_NOCOW ||
+	       type == BTRFS_ORDERED_REGULAR);
+
+	em_tree = &BTRFS_I(inode)->extent_tree;
+	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->bdev = root->fs_info->fs_devices->latest_bdev;
+	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;
+	}
+
+	do {
+		btrfs_drop_extent_cache(BTRFS_I(inode), em->start,
+				em->start + em->len - 1, 0);
+		write_lock(&em_tree->lock);
+		ret = add_extent_mapping(em_tree, em, 1);
+		write_unlock(&em_tree->lock);
+		/*
+		 * The caller has taken lock_extent(), who could race with us
+		 * to add em?
+		 */
+	} while (ret == -EEXIST);
+
+	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_read(struct extent_map *em,
+					struct buffer_head *bh_result,
+					struct inode *inode,
+					u64 start, u64 len)
+{
+	if (em->block_start == EXTENT_MAP_HOLE ||
+			test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+		return -ENOENT;
+
+	len = min(len, em->len - (start - em->start));
+
+	bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
+		inode->i_blkbits;
+	bh_result->b_size = len;
+	bh_result->b_bdev = em->bdev;
+	set_buffer_mapped(bh_result);
+
+	return 0;
+}
+
+static int btrfs_get_blocks_direct_write(struct extent_map **map,
+					 struct buffer_head *bh_result,
+					 struct inode *inode,
+					 struct btrfs_dio_data *dio_data,
+					 u64 start, u64 len)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct extent_map *em = *map;
+	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)) {
+		int type;
+		u64 block_start, orig_start, orig_block_len, ram_bytes;
+
+		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) == 1 &&
+		    btrfs_inc_nocow_writers(fs_info, block_start)) {
+			struct extent_map *em2;
+
+			em2 = btrfs_create_dio_extent(inode, start, len,
+						      orig_start, block_start,
+						      len, orig_block_len,
+						      ram_bytes, type);
+			btrfs_dec_nocow_writers(fs_info, block_start);
+			if (type == BTRFS_ORDERED_PREALLOC) {
+				free_extent_map(em);
+				*map = em = em2;
+			}
+
+			if (em2 && IS_ERR(em2)) {
+				ret = PTR_ERR(em2);
+				goto out;
+			}
+			/*
+			 * For inode marked NODATACOW or extent marked PREALLOC,
+			 * use the existing or preallocated extent, so does not
+			 * need to adjust btrfs_space_info's bytes_may_use.
+			 */
+			btrfs_free_reserved_data_space_noquota(inode, start,
+							       len);
+			goto skip_cow;
+		}
+	}
+
+	/* this will cow the extent */
+	len = bh_result->b_size;
+	free_extent_map(em);
+	*map = em = btrfs_new_extent_direct(inode, start, len);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out;
+	}
+
+	len = min(len, em->len - (start - em->start));
+
+skip_cow:
+	bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
+		inode->i_blkbits;
+	bh_result->b_size = len;
+	bh_result->b_bdev = em->bdev;
+	set_buffer_mapped(bh_result);
+
+	if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+		set_buffer_new(bh_result);
+
+	/*
+	 * Need to update the i_size under the extent lock so buffered
+	 * readers will get the updated i_size when we unlock.
+	 */
+	if (!dio_data->overwrite && start + len > i_size_read(inode))
+		i_size_write(inode, start + len);
+
+	WARN_ON(dio_data->reserve < len);
+	dio_data->reserve -= len;
+	dio_data->unsubmitted_oe_range_end = start + len;
+	current->journal_info = dio_data;
+out:
+	return ret;
+}
+
+static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
+				   struct buffer_head *bh_result, int create)
+{
+	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 = NULL;
+	u64 start = iblock << inode->i_blkbits;
+	u64 lockstart, lockend;
+	u64 len = bh_result->b_size;
+	int unlock_bits = EXTENT_LOCKED;
+	int ret = 0;
+
+	if (create)
+		unlock_bits |= EXTENT_DIRTY;
+	else
+		len = min_t(u64, len, fs_info->sectorsize);
+
+	lockstart = start;
+	lockend = start + len - 1;
+
+	if (current->journal_info) {
+		/*
+		 * Need to pull our outstanding extents and set journal_info to NULL so
+		 * that anything that needs to check if there's a transaction doesn't get
+		 * confused.
+		 */
+		dio_data = current->journal_info;
+		current->journal_info = NULL;
+	}
+
+	/*
+	 * If this errors out it's because we couldn't invalidate pagecache for
+	 * this range and we need to fallback to buffered.
+	 */
+	if (lock_extent_direct(inode, lockstart, lockend, &cached_state,
+			       create)) {
+		ret = -ENOTBLK;
+		goto err;
+	}
+
+	em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len, 0);
+	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);
+		ret = -ENOTBLK;
+		goto unlock_err;
+	}
+
+	if (create) {
+		ret = btrfs_get_blocks_direct_write(&em, bh_result, inode,
+						    dio_data, start, len);
+		if (ret < 0)
+			goto unlock_err;
+
+		/* clear and unlock the entire range */
+		clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend,
+				 unlock_bits, 1, 0, &cached_state);
+	} else {
+		ret = btrfs_get_blocks_direct_read(em, bh_result, inode,
+						   start, len);
+		/* Can be negative only if we read from a hole */
+		if (ret < 0) {
+			ret = 0;
+			free_extent_map(em);
+			goto unlock_err;
+		}
+		/*
+		 * 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 + bh_result->b_size;
+		if (lockstart < lockend) {
+			clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
+					 lockend, unlock_bits, 1, 0,
+					 &cached_state);
+		} else {
+			free_extent_state(cached_state);
+		}
+	}
+
+	free_extent_map(em);
+
+	return 0;
+
+unlock_err:
+	clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend,
+			 unlock_bits, 1, 0, &cached_state);
+err:
+	if (dio_data)
+		current->journal_info = dio_data;
+	return ret;
+}
+
+static inline blk_status_t submit_dio_repair_bio(struct inode *inode,
+						 struct bio *bio,
+						 int mirror_num)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	blk_status_t ret;
+
+	BUG_ON(bio_op(bio) == REQ_OP_WRITE);
+
+	ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DIO_REPAIR);
+	if (ret)
+		return ret;
+
+	ret = btrfs_map_bio(fs_info, bio, mirror_num, 0);
+
+	return ret;
+}
+
+static int btrfs_check_dio_repairable(struct inode *inode,
+				      struct bio *failed_bio,
+				      struct io_failure_record *failrec,
+				      int failed_mirror)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	int num_copies;
+
+	num_copies = btrfs_num_copies(fs_info, failrec->logical, failrec->len);
+	if (num_copies == 1) {
+		/*
+		 * we only have a single copy of the data, so don't bother with
+		 * all the retry and error correction code that follows. no
+		 * matter what the error is, it is very likely to persist.
+		 */
+		btrfs_debug(fs_info,
+			"Check DIO Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d",
+			num_copies, failrec->this_mirror, failed_mirror);
+		return 0;
+	}
+
+	failrec->failed_mirror = failed_mirror;
+	failrec->this_mirror++;
+	if (failrec->this_mirror == failed_mirror)
+		failrec->this_mirror++;
+
+	if (failrec->this_mirror > num_copies) {
+		btrfs_debug(fs_info,
+			"Check DIO Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d",
+			num_copies, failrec->this_mirror, failed_mirror);
+		return 0;
+	}
+
+	return 1;
+}
+
+static blk_status_t dio_read_error(struct inode *inode, struct bio *failed_bio,
+				   struct page *page, unsigned int pgoff,
+				   u64 start, u64 end, int failed_mirror,
+				   bio_end_io_t *repair_endio, void *repair_arg)
+{
+	struct io_failure_record *failrec;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
+	struct bio *bio;
+	int isector;
+	unsigned int read_mode = 0;
+	int segs;
+	int ret;
+	blk_status_t status;
+	struct bio_vec bvec;
+
+	BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);
+
+	ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
+	if (ret)
+		return errno_to_blk_status(ret);
+
+	ret = btrfs_check_dio_repairable(inode, failed_bio, failrec,
+					 failed_mirror);
+	if (!ret) {
+		free_io_failure(failure_tree, io_tree, failrec);
+		return BLK_STS_IOERR;
+	}
+
+	segs = bio_segments(failed_bio);
+	bio_get_first_bvec(failed_bio, &bvec);
+	if (segs > 1 ||
+	    (bvec.bv_len > btrfs_inode_sectorsize(inode)))
+		read_mode |= REQ_FAILFAST_DEV;
+
+	isector = start - btrfs_io_bio(failed_bio)->logical;
+	isector >>= inode->i_sb->s_blocksize_bits;
+	bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
+				pgoff, isector, repair_endio, repair_arg);
+	bio->bi_opf = REQ_OP_READ | read_mode;
+
+	btrfs_debug(BTRFS_I(inode)->root->fs_info,
+		    "repair DIO read error: submitting new dio read[%#x] to this_mirror=%d, in_validation=%d",
+		    read_mode, failrec->this_mirror, failrec->in_validation);
+
+	status = submit_dio_repair_bio(inode, bio, failrec->this_mirror);
+	if (status) {
+		free_io_failure(failure_tree, io_tree, failrec);
+		bio_put(bio);
+	}
+
+	return status;
+}
+
+struct btrfs_retry_complete {
+	struct completion done;
+	struct inode *inode;
+	u64 start;
+	int uptodate;
+};
+
+static void btrfs_retry_endio_nocsum(struct bio *bio)
+{
+	struct btrfs_retry_complete *done = bio->bi_private;
+	struct inode *inode = done->inode;
+	struct bio_vec *bvec;
+	struct extent_io_tree *io_tree, *failure_tree;
+	int i;
+
+	if (bio->bi_status)
+		goto end;
+
+	ASSERT(bio->bi_vcnt == 1);
+	io_tree = &BTRFS_I(inode)->io_tree;
+	failure_tree = &BTRFS_I(inode)->io_failure_tree;
+	ASSERT(bio_first_bvec_all(bio)->bv_len == btrfs_inode_sectorsize(inode));
+
+	done->uptodate = 1;
+	ASSERT(!bio_flagged(bio, BIO_CLONED));
+	bio_for_each_segment_all(bvec, bio, i)
+		clean_io_failure(BTRFS_I(inode)->root->fs_info, failure_tree,
+				 io_tree, done->start, bvec->bv_page,
+				 btrfs_ino(BTRFS_I(inode)), 0);
+end:
+	complete(&done->done);
+	bio_put(bio);
+}
+
+static blk_status_t __btrfs_correct_data_nocsum(struct inode *inode,
+						struct btrfs_io_bio *io_bio)
+{
+	struct btrfs_fs_info *fs_info;
+	struct bio_vec bvec;
+	struct bvec_iter iter;
+	struct btrfs_retry_complete done;
+	u64 start;
+	unsigned int pgoff;
+	u32 sectorsize;
+	int nr_sectors;
+	blk_status_t ret;
+	blk_status_t err = BLK_STS_OK;
+
+	fs_info = BTRFS_I(inode)->root->fs_info;
+	sectorsize = fs_info->sectorsize;
+
+	start = io_bio->logical;
+	done.inode = inode;
+	io_bio->bio.bi_iter = io_bio->iter;
+
+	bio_for_each_segment(bvec, &io_bio->bio, iter) {
+		nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec.bv_len);
+		pgoff = bvec.bv_offset;
+
+next_block_or_try_again:
+		done.uptodate = 0;
+		done.start = start;
+		init_completion(&done.done);
+
+		ret = dio_read_error(inode, &io_bio->bio, bvec.bv_page,
+				pgoff, start, start + sectorsize - 1,
+				io_bio->mirror_num,
+				btrfs_retry_endio_nocsum, &done);
+		if (ret) {
+			err = ret;
+			goto next;
+		}
+
+		wait_for_completion_io(&done.done);
+
+		if (!done.uptodate) {
+			/* We might have another mirror, so try again */
+			goto next_block_or_try_again;
+		}
+
+next:
+		start += sectorsize;
+
+		nr_sectors--;
+		if (nr_sectors) {
+			pgoff += sectorsize;
+			ASSERT(pgoff < PAGE_SIZE);
+			goto next_block_or_try_again;
+		}
+	}
+
+	return err;
+}
+
+static void btrfs_retry_endio(struct bio *bio)
+{
+	struct btrfs_retry_complete *done = bio->bi_private;
+	struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+	struct extent_io_tree *io_tree, *failure_tree;
+	struct inode *inode = done->inode;
+	struct bio_vec *bvec;
+	int uptodate;
+	int ret;
+	int i;
+
+	if (bio->bi_status)
+		goto end;
+
+	uptodate = 1;
+
+	ASSERT(bio->bi_vcnt == 1);
+	ASSERT(bio_first_bvec_all(bio)->bv_len == btrfs_inode_sectorsize(done->inode));
+
+	io_tree = &BTRFS_I(inode)->io_tree;
+	failure_tree = &BTRFS_I(inode)->io_failure_tree;
+
+	ASSERT(!bio_flagged(bio, BIO_CLONED));
+	bio_for_each_segment_all(bvec, bio, i) {
+		ret = __readpage_endio_check(inode, io_bio, i, bvec->bv_page,
+					     bvec->bv_offset, done->start,
+					     bvec->bv_len);
+		if (!ret)
+			clean_io_failure(BTRFS_I(inode)->root->fs_info,
+					 failure_tree, io_tree, done->start,
+					 bvec->bv_page,
+					 btrfs_ino(BTRFS_I(inode)),
+					 bvec->bv_offset);
+		else
+			uptodate = 0;
+	}
+
+	done->uptodate = uptodate;
+end:
+	complete(&done->done);
+	bio_put(bio);
+}
+
+static blk_status_t __btrfs_subio_endio_read(struct inode *inode,
+		struct btrfs_io_bio *io_bio, blk_status_t err)
+{
+	struct btrfs_fs_info *fs_info;
+	struct bio_vec bvec;
+	struct bvec_iter iter;
+	struct btrfs_retry_complete done;
+	u64 start;
+	u64 offset = 0;
+	u32 sectorsize;
+	int nr_sectors;
+	unsigned int pgoff;
+	int csum_pos;
+	bool uptodate = (err == 0);
+	int ret;
+	blk_status_t status;
+
+	fs_info = BTRFS_I(inode)->root->fs_info;
+	sectorsize = fs_info->sectorsize;
+
+	err = BLK_STS_OK;
+	start = io_bio->logical;
+	done.inode = inode;
+	io_bio->bio.bi_iter = io_bio->iter;
+
+	bio_for_each_segment(bvec, &io_bio->bio, iter) {
+		nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec.bv_len);
+
+		pgoff = bvec.bv_offset;
+next_block:
+		if (uptodate) {
+			csum_pos = BTRFS_BYTES_TO_BLKS(fs_info, offset);
+			ret = __readpage_endio_check(inode, io_bio, csum_pos,
+					bvec.bv_page, pgoff, start, sectorsize);
+			if (likely(!ret))
+				goto next;
+		}
+try_again:
+		done.uptodate = 0;
+		done.start = start;
+		init_completion(&done.done);
+
+		status = dio_read_error(inode, &io_bio->bio, bvec.bv_page,
+					pgoff, start, start + sectorsize - 1,
+					io_bio->mirror_num, btrfs_retry_endio,
+					&done);
+		if (status) {
+			err = status;
+			goto next;
+		}
+
+		wait_for_completion_io(&done.done);
+
+		if (!done.uptodate) {
+			/* We might have another mirror, so try again */
+			goto try_again;
+		}
+next:
+		offset += sectorsize;
+		start += sectorsize;
+
+		ASSERT(nr_sectors);
+
+		nr_sectors--;
+		if (nr_sectors) {
+			pgoff += sectorsize;
+			ASSERT(pgoff < PAGE_SIZE);
+			goto next_block;
+		}
+	}
+
+	return err;
+}
+
+static blk_status_t btrfs_subio_endio_read(struct inode *inode,
+		struct btrfs_io_bio *io_bio, blk_status_t err)
+{
+	bool skip_csum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
+
+	if (skip_csum) {
+		if (unlikely(err))
+			return __btrfs_correct_data_nocsum(inode, io_bio);
+		else
+			return BLK_STS_OK;
+	} else {
+		return __btrfs_subio_endio_read(inode, io_bio, err);
+	}
+}
+
+static void btrfs_endio_direct_read(struct bio *bio)
+{
+	struct btrfs_dio_private *dip = bio->bi_private;
+	struct inode *inode = dip->inode;
+	struct bio *dio_bio;
+	struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+	blk_status_t err = bio->bi_status;
+
+	if (dip->flags & BTRFS_DIO_ORIG_BIO_SUBMITTED)
+		err = btrfs_subio_endio_read(inode, io_bio, err);
+
+	unlock_extent(&BTRFS_I(inode)->io_tree, dip->logical_offset,
+		      dip->logical_offset + dip->bytes - 1);
+	dio_bio = dip->dio_bio;
+
+	kfree(dip);
+
+	dio_bio->bi_status = err;
+	dio_end_io(dio_bio);
+
+	if (io_bio->end_io)
+		io_bio->end_io(io_bio, blk_status_to_errno(err));
+	bio_put(bio);
+}
+
+static void __endio_write_update_ordered(struct inode *inode,
+					 const u64 offset, const u64 bytes,
+					 const bool uptodate)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_ordered_extent *ordered = NULL;
+	struct btrfs_workqueue *wq;
+	btrfs_work_func_t func;
+	u64 ordered_offset = offset;
+	u64 ordered_bytes = bytes;
+	u64 last_offset;
+
+	if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
+		wq = fs_info->endio_freespace_worker;
+		func = btrfs_freespace_write_helper;
+	} else {
+		wq = fs_info->endio_write_workers;
+		func = btrfs_endio_write_helper;
+	}
+
+	while (ordered_offset < offset + bytes) {
+		last_offset = ordered_offset;
+		if (btrfs_dec_test_first_ordered_pending(inode, &ordered,
+							   &ordered_offset,
+							   ordered_bytes,
+							   uptodate)) {
+			btrfs_init_work(&ordered->work, func,
+					finish_ordered_fn,
+					NULL, NULL);
+			btrfs_queue_work(wq, &ordered->work);
+		}
+		/*
+		 * If btrfs_dec_test_ordered_pending does not find any ordered
+		 * extent in the range, we can exit.
+		 */
+		if (ordered_offset == last_offset)
+			return;
+		/*
+		 * Our bio might span multiple ordered extents. In this case
+		 * we keep goin until we have accounted the whole dio.
+		 */
+		if (ordered_offset < offset + bytes) {
+			ordered_bytes = offset + bytes - ordered_offset;
+			ordered = NULL;
+		}
+	}
+}
+
+static void btrfs_endio_direct_write(struct bio *bio)
+{
+	struct btrfs_dio_private *dip = bio->bi_private;
+	struct bio *dio_bio = dip->dio_bio;
+
+	__endio_write_update_ordered(dip->inode, dip->logical_offset,
+				     dip->bytes, !bio->bi_status);
+
+	kfree(dip);
+
+	dio_bio->bi_status = bio->bi_status;
+	dio_end_io(dio_bio);
+	bio_put(bio);
+}
+
+static blk_status_t btrfs_submit_bio_start_direct_io(void *private_data,
+				    struct bio *bio, u64 offset)
+{
+	struct inode *inode = private_data;
+	blk_status_t ret;
+	ret = btrfs_csum_one_bio(inode, bio, offset, 1);
+	BUG_ON(ret); /* -ENOMEM */
+	return 0;
+}
+
+static void btrfs_end_dio_bio(struct bio *bio)
+{
+	struct btrfs_dio_private *dip = bio->bi_private;
+	blk_status_t err = bio->bi_status;
+
+	if (err)
+		btrfs_warn(BTRFS_I(dip->inode)->root->fs_info,
+			   "direct IO failed ino %llu rw %d,%u sector %#Lx len %u err no %d",
+			   btrfs_ino(BTRFS_I(dip->inode)), bio_op(bio),
+			   bio->bi_opf,
+			   (unsigned long long)bio->bi_iter.bi_sector,
+			   bio->bi_iter.bi_size, err);
+
+	if (dip->subio_endio)
+		err = dip->subio_endio(dip->inode, btrfs_io_bio(bio), err);
+
+	if (err) {
+		/*
+		 * We want to perceive the errors flag being set before
+		 * decrementing the reference count. We don't need a barrier
+		 * since atomic operations with a return value are fully
+		 * ordered as per atomic_t.txt
+		 */
+		dip->errors = 1;
+	}
+
+	/* if there are more bios still pending for this dio, just exit */
+	if (!atomic_dec_and_test(&dip->pending_bios))
+		goto out;
+
+	if (dip->errors) {
+		bio_io_error(dip->orig_bio);
+	} else {
+		dip->dio_bio->bi_status = BLK_STS_OK;
+		bio_endio(dip->orig_bio);
+	}
+out:
+	bio_put(bio);
+}
+
+static inline blk_status_t btrfs_lookup_and_bind_dio_csum(struct inode *inode,
+						 struct btrfs_dio_private *dip,
+						 struct bio *bio,
+						 u64 file_offset)
+{
+	struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+	struct btrfs_io_bio *orig_io_bio = btrfs_io_bio(dip->orig_bio);
+	blk_status_t ret;
+
+	/*
+	 * We load all the csum data we need when we submit
+	 * the first bio to reduce the csum tree search and
+	 * contention.
+	 */
+	if (dip->logical_offset == file_offset) {
+		ret = btrfs_lookup_bio_sums_dio(inode, dip->orig_bio,
+						file_offset);
+		if (ret)
+			return ret;
+	}
+
+	if (bio == dip->orig_bio)
+		return 0;
+
+	file_offset -= dip->logical_offset;
+	file_offset >>= inode->i_sb->s_blocksize_bits;
+	io_bio->csum = (u8 *)(((u32 *)orig_io_bio->csum) + file_offset);
+
+	return 0;
+}
+
+static inline blk_status_t btrfs_submit_dio_bio(struct bio *bio,
+		struct inode *inode, u64 file_offset, int async_submit)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_dio_private *dip = bio->bi_private;
+	bool write = bio_op(bio) == REQ_OP_WRITE;
+	blk_status_t ret;
+
+	/* Check btrfs_submit_bio_hook() for rules about async submit. */
+	if (async_submit)
+		async_submit = !atomic_read(&BTRFS_I(inode)->sync_writers);
+
+	if (!write) {
+		ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
+		if (ret)
+			goto err;
+	}
+
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
+		goto map;
+
+	if (write && async_submit) {
+		ret = btrfs_wq_submit_bio(fs_info, bio, 0, 0,
+					  file_offset, inode,
+					  btrfs_submit_bio_start_direct_io);
+		goto err;
+	} else if (write) {
+		/*
+		 * If we aren't doing async submit, calculate the csum of the
+		 * bio now.
+		 */
+		ret = btrfs_csum_one_bio(inode, bio, file_offset, 1);
+		if (ret)
+			goto err;
+	} else {
+		ret = btrfs_lookup_and_bind_dio_csum(inode, dip, bio,
+						     file_offset);
+		if (ret)
+			goto err;
+	}
+map:
+	ret = btrfs_map_bio(fs_info, bio, 0, 0);
+err:
+	return ret;
+}
+
+static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip)
+{
+	struct inode *inode = dip->inode;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct bio *bio;
+	struct bio *orig_bio = dip->orig_bio;
+	u64 start_sector = orig_bio->bi_iter.bi_sector;
+	u64 file_offset = dip->logical_offset;
+	u64 map_length;
+	int async_submit = 0;
+	u64 submit_len;
+	int clone_offset = 0;
+	int clone_len;
+	int ret;
+	blk_status_t status;
+
+	map_length = orig_bio->bi_iter.bi_size;
+	submit_len = map_length;
+	ret = btrfs_map_block(fs_info, btrfs_op(orig_bio), start_sector << 9,
+			      &map_length, NULL, 0);
+	if (ret)
+		return -EIO;
+
+	if (map_length >= submit_len) {
+		bio = orig_bio;
+		dip->flags |= BTRFS_DIO_ORIG_BIO_SUBMITTED;
+		goto submit;
+	}
+
+	/* async crcs make it difficult to collect full stripe writes. */
+	if (btrfs_data_alloc_profile(fs_info) & BTRFS_BLOCK_GROUP_RAID56_MASK)
+		async_submit = 0;
+	else
+		async_submit = 1;
+
+	/* bio split */
+	ASSERT(map_length <= INT_MAX);
+	do {
+		clone_len = min_t(int, submit_len, map_length);
+
+		/*
+		 * This will never fail as it's passing GPF_NOFS and
+		 * the allocation is backed by btrfs_bioset.
+		 */
+		bio = btrfs_bio_clone_partial(orig_bio, clone_offset,
+					      clone_len);
+		bio->bi_private = dip;
+		bio->bi_end_io = btrfs_end_dio_bio;
+		btrfs_io_bio(bio)->logical = file_offset;
+
+		ASSERT(submit_len >= clone_len);
+		submit_len -= clone_len;
+		if (submit_len == 0)
+			break;
+
+		/*
+		 * Increase the count before we submit the bio so we know
+		 * the end IO handler won't happen before we increase the
+		 * count. Otherwise, the dip might get freed before we're
+		 * done setting it up.
+		 */
+		atomic_inc(&dip->pending_bios);
+
+		status = btrfs_submit_dio_bio(bio, inode, file_offset,
+						async_submit);
+		if (status) {
+			bio_put(bio);
+			atomic_dec(&dip->pending_bios);
+			goto out_err;
+		}
+
+		clone_offset += clone_len;
+		start_sector += clone_len >> 9;
+		file_offset += clone_len;
+
+		map_length = submit_len;
+		ret = btrfs_map_block(fs_info, btrfs_op(orig_bio),
+				      start_sector << 9, &map_length, NULL, 0);
+		if (ret)
+			goto out_err;
+	} while (submit_len > 0);
+
+submit:
+	status = btrfs_submit_dio_bio(bio, inode, file_offset, async_submit);
+	if (!status)
+		return 0;
+
+	if (bio != orig_bio)
+		bio_put(bio);
+out_err:
+	dip->errors = 1;
+	/*
+	 * Before atomic variable goto zero, we must  make sure dip->errors is
+	 * perceived to be set. This ordering is ensured by the fact that an
+	 * atomic operations with a return value are fully ordered as per
+	 * atomic_t.txt
+	 */
+	if (atomic_dec_and_test(&dip->pending_bios))
+		bio_io_error(dip->orig_bio);
+
+	/* bio_end_io() will handle error, so we needn't return it */
+	return 0;
+}
+
+static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
+				loff_t file_offset)
+{
+	struct btrfs_dio_private *dip = NULL;
+	struct bio *bio = NULL;
+	struct btrfs_io_bio *io_bio;
+	bool write = (bio_op(dio_bio) == REQ_OP_WRITE);
+	int ret = 0;
+
+	bio = btrfs_bio_clone(dio_bio);
+
+	dip = kzalloc(sizeof(*dip), GFP_NOFS);
+	if (!dip) {
+		ret = -ENOMEM;
+		goto free_ordered;
+	}
+
+	dip->private = dio_bio->bi_private;
+	dip->inode = inode;
+	dip->logical_offset = file_offset;
+	dip->bytes = dio_bio->bi_iter.bi_size;
+	dip->disk_bytenr = (u64)dio_bio->bi_iter.bi_sector << 9;
+	bio->bi_private = dip;
+	dip->orig_bio = bio;
+	dip->dio_bio = dio_bio;
+	atomic_set(&dip->pending_bios, 1);
+	io_bio = btrfs_io_bio(bio);
+	io_bio->logical = file_offset;
+
+	if (write) {
+		bio->bi_end_io = btrfs_endio_direct_write;
+	} else {
+		bio->bi_end_io = btrfs_endio_direct_read;
+		dip->subio_endio = btrfs_subio_endio_read;
+	}
+
+	/*
+	 * Reset the range for unsubmitted ordered extents (to a 0 length range)
+	 * even if we fail to submit a bio, because in such case we do the
+	 * corresponding error handling below and it must not be done a second
+	 * time by btrfs_direct_IO().
+	 */
+	if (write) {
+		struct btrfs_dio_data *dio_data = current->journal_info;
+
+		dio_data->unsubmitted_oe_range_end = dip->logical_offset +
+			dip->bytes;
+		dio_data->unsubmitted_oe_range_start =
+			dio_data->unsubmitted_oe_range_end;
+	}
+
+	ret = btrfs_submit_direct_hook(dip);
+	if (!ret)
+		return;
+
+	if (io_bio->end_io)
+		io_bio->end_io(io_bio, ret);
+
+free_ordered:
+	/*
+	 * If we arrived here it means either we failed to submit the dip
+	 * or we either failed to clone the dio_bio or failed to allocate the
+	 * dip. If we cloned the dio_bio and allocated the dip, we can just
+	 * call bio_endio against our io_bio so that we get proper resource
+	 * cleanup if we fail to submit the dip, otherwise, we must do the
+	 * same as btrfs_endio_direct_[write|read] because we can't call these
+	 * callbacks - they require an allocated dip and a clone of dio_bio.
+	 */
+	if (bio && dip) {
+		bio_io_error(bio);
+		/*
+		 * The end io callbacks free our dip, do the final put on bio
+		 * and all the cleanup and final put for dio_bio (through
+		 * dio_end_io()).
+		 */
+		dip = NULL;
+		bio = NULL;
+	} else {
+		if (write)
+			__endio_write_update_ordered(inode,
+						file_offset,
+						dio_bio->bi_iter.bi_size,
+						false);
+		else
+			unlock_extent(&BTRFS_I(inode)->io_tree, file_offset,
+			      file_offset + dio_bio->bi_iter.bi_size - 1);
+
+		dio_bio->bi_status = BLK_STS_IOERR;
+		/*
+		 * Releases and cleans up our dio_bio, no need to bio_put()
+		 * nor bio_endio()/bio_io_error() against dio_bio.
+		 */
+		dio_end_io(dio_bio);
+	}
+	if (bio)
+		bio_put(bio);
+	kfree(dip);
+}
+
+static ssize_t check_direct_IO(struct btrfs_fs_info *fs_info,
+			       const struct iov_iter *iter, loff_t offset)
+{
+	int seg;
+	int i;
+	unsigned int blocksize_mask = fs_info->sectorsize - 1;
+	ssize_t retval = -EINVAL;
+
+	if (offset & blocksize_mask)
+		goto out;
+
+	if (iov_iter_alignment(iter) & blocksize_mask)
+		goto out;
+
+	/* If this is a write we don't need to check anymore */
+	if (iov_iter_rw(iter) != READ || !iter_is_iovec(iter))
+		return 0;
+	/*
+	 * Check to make sure we don't have duplicate iov_base's in this
+	 * iovec, if so return EINVAL, otherwise we'll get csum errors
+	 * when reading back.
+	 */
+	for (seg = 0; seg < iter->nr_segs; seg++) {
+		for (i = seg + 1; i < iter->nr_segs; i++) {
+			if (iter->iov[seg].iov_base == iter->iov[i].iov_base)
+				goto out;
+		}
+	}
+	retval = 0;
+out:
+	return retval;
+}
+
+static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_dio_data dio_data = { 0 };
+	struct extent_changeset *data_reserved = NULL;
+	loff_t offset = iocb->ki_pos;
+	size_t count = 0;
+	int flags = 0;
+	bool wakeup = true;
+	bool relock = false;
+	ssize_t ret;
+
+	if (check_direct_IO(fs_info, iter, offset))
+		return 0;
+
+	inode_dio_begin(inode);
+
+	/*
+	 * The generic stuff 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.
+	 */
+	count = iov_iter_count(iter);
+	if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+		     &BTRFS_I(inode)->runtime_flags))
+		filemap_fdatawrite_range(inode->i_mapping, offset,
+					 offset + count - 1);
+
+	if (iov_iter_rw(iter) == WRITE) {
+		/*
+		 * If the write DIO is beyond the EOF, we need update
+		 * the isize, but it is protected by i_mutex. So we can
+		 * not unlock the i_mutex at this case.
+		 */
+		if (offset + count <= inode->i_size) {
+			dio_data.overwrite = 1;
+			inode_unlock(inode);
+			relock = true;
+		}
+		ret = btrfs_delalloc_reserve_space(inode, &data_reserved,
+						   offset, count);
+		if (ret)
+			goto out;
+
+		/*
+		 * We need to know how many extents we reserved so that we can
+		 * do the accounting properly if we go over the number we
+		 * originally calculated.  Abuse current->journal_info for this.
+		 */
+		dio_data.reserve = round_up(count,
+					    fs_info->sectorsize);
+		dio_data.unsubmitted_oe_range_start = (u64)offset;
+		dio_data.unsubmitted_oe_range_end = (u64)offset;
+		current->journal_info = &dio_data;
+		down_read(&BTRFS_I(inode)->dio_sem);
+	} else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,
+				     &BTRFS_I(inode)->runtime_flags)) {
+		inode_dio_end(inode);
+		flags = DIO_LOCKING | DIO_SKIP_HOLES;
+		wakeup = false;
+	}
+
+	ret = __blockdev_direct_IO(iocb, inode,
+				   fs_info->fs_devices->latest_bdev,
+				   iter, btrfs_get_blocks_direct, NULL,
+				   btrfs_submit_direct, flags);
+	if (iov_iter_rw(iter) == WRITE) {
+		up_read(&BTRFS_I(inode)->dio_sem);
+		current->journal_info = NULL;
+		if (ret < 0 && ret != -EIOCBQUEUED) {
+			if (dio_data.reserve)
+				btrfs_delalloc_release_space(inode, data_reserved,
+					offset, dio_data.reserve, true);
+			/*
+			 * On error we might have left some ordered extents
+			 * without submitting corresponding bios for them, so
+			 * cleanup them up to avoid other tasks getting them
+			 * and waiting for them to complete forever.
+			 */
+			if (dio_data.unsubmitted_oe_range_start <
+			    dio_data.unsubmitted_oe_range_end)
+				__endio_write_update_ordered(inode,
+					dio_data.unsubmitted_oe_range_start,
+					dio_data.unsubmitted_oe_range_end -
+					dio_data.unsubmitted_oe_range_start,
+					false);
+		} else if (ret >= 0 && (size_t)ret < count)
+			btrfs_delalloc_release_space(inode, data_reserved,
+					offset, count - (size_t)ret, true);
+		btrfs_delalloc_release_extents(BTRFS_I(inode), count);
+	}
+out:
+	if (wakeup)
+		inode_dio_end(inode);
+	if (relock)
+		inode_lock(inode);
+
+	extent_changeset_free(data_reserved);
+	return ret;
+}
+
+#define BTRFS_FIEMAP_FLAGS	(FIEMAP_FLAG_SYNC)
+
+static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+		__u64 start, __u64 len)
+{
+	int	ret;
+
+	ret = fiemap_check_flags(fieinfo, BTRFS_FIEMAP_FLAGS);
+	if (ret)
+		return ret;
+
+	return extent_fiemap(inode, fieinfo, start, len);
+}
+
+int btrfs_readpage(struct file *file, struct page *page)
+{
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+	return extent_read_full_page(tree, page, btrfs_get_extent, 0);
+}
+
+static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct inode *inode = page->mapping->host;
+	int ret;
+
+	if (current->flags & PF_MEMALLOC) {
+		redirty_page_for_writepage(wbc, page);
+		unlock_page(page);
+		return 0;
+	}
+
+	/*
+	 * If we are under memory pressure we will call this directly from the
+	 * VM, we need to make sure we have the inode referenced for the ordered
+	 * extent.  If not just return like we didn't do anything.
+	 */
+	if (!igrab(inode)) {
+		redirty_page_for_writepage(wbc, page);
+		return AOP_WRITEPAGE_ACTIVATE;
+	}
+	ret = extent_write_full_page(page, wbc);
+	btrfs_add_delayed_iput(inode);
+	return ret;
+}
+
+static int btrfs_writepages(struct address_space *mapping,
+			    struct writeback_control *wbc)
+{
+	return extent_writepages(mapping, wbc);
+}
+
+static int
+btrfs_readpages(struct file *file, struct address_space *mapping,
+		struct list_head *pages, unsigned nr_pages)
+{
+	return extent_readpages(mapping, pages, nr_pages);
+}
+
+static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
+{
+	int ret = try_release_extent_mapping(page, gfp_flags);
+	if (ret == 1) {
+		ClearPagePrivate(page);
+		set_page_private(page, 0);
+		put_page(page);
+	}
+	return ret;
+}
+
+static int btrfs_releasepage(struct page *page, gfp_t gfp_flags)
+{
+	if (PageWriteback(page) || PageDirty(page))
+		return 0;
+	return __btrfs_releasepage(page, gfp_flags);
+}
+
+static void btrfs_invalidatepage(struct page *page, unsigned int offset,
+				 unsigned int length)
+{
+	struct inode *inode = page->mapping->host;
+	struct extent_io_tree *tree;
+	struct btrfs_ordered_extent *ordered;
+	struct extent_state *cached_state = NULL;
+	u64 page_start = page_offset(page);
+	u64 page_end = page_start + PAGE_SIZE - 1;
+	u64 start;
+	u64 end;
+	int inode_evicting = inode->i_state & I_FREEING;
+
+	/*
+	 * we have the page locked, so new writeback can't start,
+	 * and the dirty bit won't be cleared while we are here.
+	 *
+	 * Wait for IO on this page so that we can safely clear
+	 * the PagePrivate2 bit and do ordered accounting
+	 */
+	wait_on_page_writeback(page);
+
+	tree = &BTRFS_I(inode)->io_tree;
+	if (offset) {
+		btrfs_releasepage(page, GFP_NOFS);
+		return;
+	}
+
+	if (!inode_evicting)
+		lock_extent_bits(tree, page_start, page_end, &cached_state);
+again:
+	start = page_start;
+	ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), start,
+					page_end - start + 1);
+	if (ordered) {
+		end = min(page_end, ordered->file_offset + ordered->len - 1);
+		/*
+		 * IO on this page will never be started, so we need
+		 * to account for any ordered extents now
+		 */
+		if (!inode_evicting)
+			clear_extent_bit(tree, start, end,
+					 EXTENT_DIRTY | EXTENT_DELALLOC |
+					 EXTENT_DELALLOC_NEW |
+					 EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
+					 EXTENT_DEFRAG, 1, 0, &cached_state);
+		/*
+		 * whoever cleared the private bit is responsible
+		 * for the finish_ordered_io
+		 */
+		if (TestClearPagePrivate2(page)) {
+			struct btrfs_ordered_inode_tree *tree;
+			u64 new_len;
+
+			tree = &BTRFS_I(inode)->ordered_tree;
+
+			spin_lock_irq(&tree->lock);
+			set_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags);
+			new_len = start - ordered->file_offset;
+			if (new_len < ordered->truncated_len)
+				ordered->truncated_len = new_len;
+			spin_unlock_irq(&tree->lock);
+
+			if (btrfs_dec_test_ordered_pending(inode, &ordered,
+							   start,
+							   end - start + 1, 1))
+				btrfs_finish_ordered_io(ordered);
+		}
+		btrfs_put_ordered_extent(ordered);
+		if (!inode_evicting) {
+			cached_state = NULL;
+			lock_extent_bits(tree, start, end,
+					 &cached_state);
+		}
+
+		start = end + 1;
+		if (start < page_end)
+			goto again;
+	}
+
+	/*
+	 * Qgroup reserved space handler
+	 * Page here will be either
+	 * 1) Already written to disk or ordered extent already submitted
+	 *    Then its QGROUP_RESERVED bit in io_tree is already cleaned.
+	 *    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, page_start, PAGE_SIZE);
+	if (!inode_evicting) {
+		clear_extent_bit(tree, page_start, page_end,
+				 EXTENT_LOCKED | EXTENT_DIRTY |
+				 EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+				 EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 1, 1,
+				 &cached_state);
+
+		__btrfs_releasepage(page, GFP_NOFS);
+	}
+
+	ClearPageChecked(page);
+	if (PagePrivate(page)) {
+		ClearPagePrivate(page);
+		set_page_private(page, 0);
+		put_page(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;
+	char *kaddr;
+	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_writepage() 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(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:
+	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_bits(io_tree, page_start, page_end, &cached_state);
+	set_page_extent_mapped(page);
+
+	/*
+	 * 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_cached(io_tree, page_start, page_end,
+				     &cached_state);
+		unlock_page(page);
+		btrfs_start_ordered_extent(inode, ordered, 1);
+		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(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_DIRTY | EXTENT_DELALLOC |
+			  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
+			  0, 0, &cached_state);
+
+	ret2 = btrfs_set_extent_delalloc(inode, page_start, end, 0,
+					&cached_state, 0);
+	if (ret2) {
+		unlock_extent_cached(io_tree, page_start, page_end,
+				     &cached_state);
+		ret = VM_FAULT_SIGBUS;
+		goto out_unlock;
+	}
+	ret2 = 0;
+
+	/* page is wholly or partially inside EOF */
+	if (page_start + PAGE_SIZE > size)
+		zero_start = size & ~PAGE_MASK;
+	else
+		zero_start = PAGE_SIZE;
+
+	if (zero_start != PAGE_SIZE) {
+		kaddr = kmap(page);
+		memset(kaddr + zero_start, 0, PAGE_SIZE - zero_start);
+		flush_dcache_page(page);
+		kunmap(page);
+	}
+	ClearPageChecked(page);
+	set_page_dirty(page);
+	SetPageUptodate(page);
+
+	BTRFS_I(inode)->last_trans = fs_info->generation;
+	BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;
+	BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->root->last_log_commit;
+
+	unlock_extent_cached(io_tree, page_start, page_end, &cached_state);
+
+	if (!ret2) {
+		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);
+out:
+	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
+	btrfs_delalloc_release_space(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 inode *inode, bool skip_writeback)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_block_rsv *rsv;
+	int ret;
+	struct btrfs_trans_handle *trans;
+	u64 mask = fs_info->sectorsize - 1;
+	u64 min_size = btrfs_calc_trunc_metadata_size(fs_info, 1);
+
+	if (!skip_writeback) {
+		ret = btrfs_wait_ordered_range(inode, 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 = 1;
+
+	/*
+	 * 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, 0);
+	BUG_ON(ret);
+
+	/*
+	 * 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.
+	 */
+	set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(inode)->runtime_flags);
+	trans->block_rsv = rsv;
+
+	while (1) {
+		ret = btrfs_truncate_inode_items(trans, root, inode,
+						 inode->i_size,
+						 BTRFS_EXTENT_DATA_KEY);
+		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);
+		ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
+					      rsv, min_size, 0);
+		BUG_ON(ret);	/* shouldn't happen */
+		trans->block_rsv = rsv;
+	}
+
+	/*
+	 * We can't call btrfs_truncate_block inside a trans handle as we could
+	 * deadlock with freeze, if we got 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 == NEED_TRUNCATE_BLOCK) {
+		btrfs_end_transaction(trans);
+		btrfs_btree_balance_dirty(fs_info);
+
+		ret = btrfs_truncate_block(inode, 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_ordered_update_i_size(inode, inode->i_size, NULL);
+	}
+
+	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);
+
+	return ret;
+}
+
+/*
+ * create a new subvolume directory/inode (helper for the ioctl).
+ */
+int btrfs_create_subvol_root(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *new_root,
+			     struct btrfs_root *parent_root,
+			     u64 new_dirid)
+{
+	struct inode *inode;
+	int err;
+	u64 index = 0;
+
+	inode = btrfs_new_inode(trans, new_root, NULL, "..", 2,
+				new_dirid, new_dirid,
+				S_IFDIR | (~current_umask() & S_IRWXUGO),
+				&index);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+	inode->i_op = &btrfs_dir_inode_operations;
+	inode->i_fop = &btrfs_dir_file_operations;
+
+	set_nlink(inode, 1);
+	btrfs_i_size_write(BTRFS_I(inode), 0);
+	unlock_new_inode(inode);
+
+	err = btrfs_subvol_inherit_props(trans, new_root, parent_root);
+	if (err)
+		btrfs_err(new_root->fs_info,
+			  "error inheriting subvolume %llu properties: %d",
+			  new_root->root_key.objectid, err);
+
+	err = btrfs_update_inode(trans, new_root, inode);
+
+	iput(inode);
+	return err;
+}
+
+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 = kmem_cache_alloc(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->csum_bytes = 0;
+	ei->index_cnt = (u64)-1;
+	ei->dir_index = 0;
+	ei->last_unlink_trans = 0;
+	ei->last_link_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(&ei->io_tree, inode);
+	extent_io_tree_init(&ei->io_failure_tree, inode);
+	ei->io_tree.track_uptodate = 1;
+	ei->io_failure_tree.track_uptodate = 1;
+	atomic_set(&ei->sync_writers, 0);
+	mutex_init(&ei->log_mutex);
+	mutex_init(&ei->delalloc_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->dio_sem);
+
+	return inode;
+}
+
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+void btrfs_test_destroy_inode(struct inode *inode)
+{
+	btrfs_drop_extent_cache(BTRFS_I(inode), 0, (u64)-1, 0);
+	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
+}
+#endif
+
+static void btrfs_i_callback(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
+}
+
+void btrfs_destroy_inode(struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+
+	WARN_ON(!hlist_empty(&inode->i_dentry));
+	WARN_ON(inode->i_data.nrpages);
+	WARN_ON(BTRFS_I(inode)->block_rsv.reserved);
+	WARN_ON(BTRFS_I(inode)->block_rsv.size);
+	WARN_ON(BTRFS_I(inode)->outstanding_extents);
+	WARN_ON(BTRFS_I(inode)->delalloc_bytes);
+	WARN_ON(BTRFS_I(inode)->new_delalloc_bytes);
+	WARN_ON(BTRFS_I(inode)->csum_bytes);
+	WARN_ON(BTRFS_I(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)
+		goto free;
+
+	while (1) {
+		ordered = btrfs_lookup_first_ordered_extent(inode, (u64)-1);
+		if (!ordered)
+			break;
+		else {
+			btrfs_err(fs_info,
+				  "found ordered extent %llu %llu on inode cleanup",
+				  ordered->file_offset, ordered->len);
+			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_cache(BTRFS_I(inode), 0, (u64)-1, 0);
+free:
+	call_rcu(&inode->i_rcu, btrfs_i_callback);
+}
+
+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 = (struct btrfs_inode *) 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();
+	kmem_cache_destroy(btrfs_inode_cachep);
+	kmem_cache_destroy(btrfs_trans_handle_cachep);
+	kmem_cache_destroy(btrfs_path_cachep);
+	kmem_cache_destroy(btrfs_free_space_cachep);
+	kmem_cache_destroy(btrfs_free_space_bitmap_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;
+
+	btrfs_trans_handle_cachep = kmem_cache_create("btrfs_trans_handle",
+			sizeof(struct btrfs_trans_handle), 0,
+			SLAB_TEMPORARY | SLAB_MEM_SPREAD, NULL);
+	if (!btrfs_trans_handle_cachep)
+		goto fail;
+
+	btrfs_path_cachep = kmem_cache_create("btrfs_path",
+			sizeof(struct btrfs_path), 0,
+			SLAB_MEM_SPREAD, NULL);
+	if (!btrfs_path_cachep)
+		goto fail;
+
+	btrfs_free_space_cachep = kmem_cache_create("btrfs_free_space",
+			sizeof(struct btrfs_free_space), 0,
+			SLAB_MEM_SPREAD, NULL);
+	if (!btrfs_free_space_cachep)
+		goto fail;
+
+	btrfs_free_space_bitmap_cachep = kmem_cache_create("btrfs_free_space_bitmap",
+							PAGE_SIZE, PAGE_SIZE,
+							SLAB_MEM_SPREAD, NULL);
+	if (!btrfs_free_space_bitmap_cachep)
+		goto fail;
+
+	return 0;
+fail:
+	btrfs_destroy_cachep();
+	return -ENOMEM;
+}
+
+static int btrfs_getattr(const struct path *path, struct kstat *stat,
+			 u32 request_mask, unsigned int flags)
+{
+	u64 delalloc_bytes;
+	struct inode *inode = d_inode(path->dentry);
+	u32 blocksize = inode->i_sb->s_blocksize;
+	u32 bi_flags = BTRFS_I(inode)->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;
+
+	stat->attributes_mask |= (STATX_ATTR_APPEND |
+				  STATX_ATTR_COMPRESSED |
+				  STATX_ATTR_IMMUTABLE |
+				  STATX_ATTR_NODUMP);
+
+	generic_fillattr(inode, stat);
+	stat->dev = BTRFS_I(inode)->root->anon_dev;
+
+	spin_lock(&BTRFS_I(inode)->lock);
+	delalloc_bytes = BTRFS_I(inode)->new_delalloc_bytes;
+	spin_unlock(&BTRFS_I(inode)->lock);
+	stat->blocks = (ALIGN(inode_get_bytes(inode), blocksize) +
+			ALIGN(delalloc_bytes, blocksize)) >> 9;
+	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;
+	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 timespec64 ctime = current_time(old_inode);
+	struct dentry *parent;
+	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;
+	bool root_log_pinned = false;
+	bool dest_log_pinned = false;
+	struct btrfs_log_ctx ctx_root;
+	struct btrfs_log_ctx ctx_dest;
+	bool sync_log_root = false;
+	bool sync_log_dest = false;
+	bool commit_transaction = false;
+
+	/*
+	 * 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;
+
+	btrfs_init_log_ctx(&ctx_root, old_inode);
+	btrfs_init_log_ctx(&ctx_dest, new_inode);
+
+	/* 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);
+
+	/*
+	 * We want to reserve the absolute worst case amount of items.  So if
+	 * both inodes are subvols and we need to unlink them then that would
+	 * require 4 item modifications, but if they are both normal inodes it
+	 * would require 5 item modifications, so we'll assume their normal
+	 * inodes.  So 5 * 2 is 10, plus 2 for the new links, so 12 total items
+	 * should cover the worst case number of items we'll modify.
+	 */
+	trans = btrfs_start_transaction(root, 12);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_notrans;
+	}
+
+	if (dest != root)
+		btrfs_record_root_in_trans(trans, dest);
+
+	/*
+	 * 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(fs_info, trans);
+	} else {
+		btrfs_pin_log_trans(root);
+		root_log_pinned = true;
+		ret = btrfs_insert_inode_ref(trans, dest,
+					     new_dentry->d_name.name,
+					     new_dentry->d_name.len,
+					     old_ino,
+					     btrfs_ino(BTRFS_I(new_dir)),
+					     old_idx);
+		if (ret)
+			goto out_fail;
+	}
+
+	/* And now for the dest. */
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/* force full log commit if subvolume involved. */
+		btrfs_set_log_full_commit(fs_info, trans);
+	} else {
+		btrfs_pin_log_trans(dest);
+		dest_log_pinned = true;
+		ret = btrfs_insert_inode_ref(trans, root,
+					     old_dentry->d_name.name,
+					     old_dentry->d_name.len,
+					     new_ino,
+					     btrfs_ino(BTRFS_I(old_dir)),
+					     new_idx);
+		if (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);
+	old_dir->i_ctime = old_dir->i_mtime = ctime;
+	new_dir->i_ctime = new_dir->i_mtime = ctime;
+	old_inode->i_ctime = ctime;
+	new_inode->i_ctime = ctime;
+
+	if (old_dentry->d_parent != new_dentry->d_parent) {
+		btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
+				BTRFS_I(old_inode), 1);
+		btrfs_record_unlink_dir(trans, BTRFS_I(new_dir),
+				BTRFS_I(new_inode), 1);
+	}
+
+	/* src is a subvolume */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		ret = btrfs_unlink_subvol(trans, old_dir, old_dentry);
+	} else { /* src is an inode */
+		ret = __btrfs_unlink_inode(trans, root, BTRFS_I(old_dir),
+					   BTRFS_I(old_dentry->d_inode),
+					   old_dentry->d_name.name,
+					   old_dentry->d_name.len);
+		if (!ret)
+			ret = btrfs_update_inode(trans, root, 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, new_dir, new_dentry);
+	} else { /* dest is an inode */
+		ret = __btrfs_unlink_inode(trans, dest, BTRFS_I(new_dir),
+					   BTRFS_I(new_dentry->d_inode),
+					   new_dentry->d_name.name,
+					   new_dentry->d_name.len);
+		if (!ret)
+			ret = btrfs_update_inode(trans, dest, 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_dentry->d_name.name,
+			     new_dentry->d_name.len, 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_dentry->d_name.name,
+			     old_dentry->d_name.len, 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;
+
+	if (root_log_pinned) {
+		parent = new_dentry->d_parent;
+		ret = btrfs_log_new_name(trans, BTRFS_I(old_inode),
+					 BTRFS_I(old_dir), parent,
+					 false, &ctx_root);
+		if (ret == BTRFS_NEED_LOG_SYNC)
+			sync_log_root = true;
+		else if (ret == BTRFS_NEED_TRANS_COMMIT)
+			commit_transaction = true;
+		ret = 0;
+		btrfs_end_log_trans(root);
+		root_log_pinned = false;
+	}
+	if (dest_log_pinned) {
+		if (!commit_transaction) {
+			parent = old_dentry->d_parent;
+			ret = btrfs_log_new_name(trans, BTRFS_I(new_inode),
+						 BTRFS_I(new_dir), parent,
+						 false, &ctx_dest);
+			if (ret == BTRFS_NEED_LOG_SYNC)
+				sync_log_dest = true;
+			else if (ret == BTRFS_NEED_TRANS_COMMIT)
+				commit_transaction = true;
+			ret = 0;
+		}
+		btrfs_end_log_trans(dest);
+		dest_log_pinned = false;
+	}
+out_fail:
+	/*
+	 * If we have pinned a log and an error happened, we unpin tasks
+	 * trying to sync the log and force them to fallback to a transaction
+	 * commit if the log currently contains any of the inodes involved in
+	 * this rename operation (to ensure we do not persist a log with an
+	 * inconsistent state for any of these inodes or leading to any
+	 * inconsistencies when replayed). If the transaction was aborted, the
+	 * abortion reason is propagated to userspace when attempting to commit
+	 * the transaction. If the log does not contain any of these inodes, we
+	 * allow the tasks to sync it.
+	 */
+	if (ret && (root_log_pinned || dest_log_pinned)) {
+		if (btrfs_inode_in_log(BTRFS_I(old_dir), fs_info->generation) ||
+		    btrfs_inode_in_log(BTRFS_I(new_dir), fs_info->generation) ||
+		    btrfs_inode_in_log(BTRFS_I(old_inode), fs_info->generation) ||
+		    (new_inode &&
+		     btrfs_inode_in_log(BTRFS_I(new_inode), fs_info->generation)))
+			btrfs_set_log_full_commit(fs_info, trans);
+
+		if (root_log_pinned) {
+			btrfs_end_log_trans(root);
+			root_log_pinned = false;
+		}
+		if (dest_log_pinned) {
+			btrfs_end_log_trans(dest);
+			dest_log_pinned = false;
+		}
+	}
+	if (!ret && sync_log_root && !commit_transaction) {
+		ret = btrfs_sync_log(trans, BTRFS_I(old_inode)->root,
+				     &ctx_root);
+		if (ret)
+			commit_transaction = true;
+	}
+	if (!ret && sync_log_dest && !commit_transaction) {
+		ret = btrfs_sync_log(trans, BTRFS_I(new_inode)->root,
+				     &ctx_dest);
+		if (ret)
+			commit_transaction = true;
+	}
+	if (commit_transaction) {
+		/*
+		 * We may have set commit_transaction when logging the new name
+		 * in the destination root, in which case we left the source
+		 * root context in the list of log contextes. So make sure we
+		 * remove it to avoid invalid memory accesses, since the context
+		 * was allocated in our stack frame.
+		 */
+		if (sync_log_root) {
+			mutex_lock(&root->log_mutex);
+			list_del_init(&ctx_root.list);
+			mutex_unlock(&root->log_mutex);
+		}
+		ret = btrfs_commit_transaction(trans);
+	} else {
+		int ret2;
+
+		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);
+
+	ASSERT(list_empty(&ctx_root.list));
+	ASSERT(list_empty(&ctx_dest.list));
+
+	return ret;
+}
+
+static int btrfs_whiteout_for_rename(struct btrfs_trans_handle *trans,
+				     struct btrfs_root *root,
+				     struct inode *dir,
+				     struct dentry *dentry)
+{
+	int ret;
+	struct inode *inode;
+	u64 objectid;
+	u64 index;
+
+	ret = btrfs_find_free_ino(root, &objectid);
+	if (ret)
+		return ret;
+
+	inode = btrfs_new_inode(trans, root, dir,
+				dentry->d_name.name,
+				dentry->d_name.len,
+				btrfs_ino(BTRFS_I(dir)),
+				objectid,
+				S_IFCHR | WHITEOUT_MODE,
+				&index);
+
+	if (IS_ERR(inode)) {
+		ret = PTR_ERR(inode);
+		return ret;
+	}
+
+	inode->i_op = &btrfs_special_inode_operations;
+	init_special_inode(inode, inode->i_mode,
+		WHITEOUT_DEV);
+
+	ret = btrfs_init_inode_security(trans, inode, dir,
+				&dentry->d_name);
+	if (ret)
+		goto out;
+
+	ret = btrfs_add_nondir(trans, BTRFS_I(dir), dentry,
+				BTRFS_I(inode), 0, index);
+	if (ret)
+		goto out;
+
+	ret = btrfs_update_inode(trans, root, inode);
+out:
+	unlock_new_inode(inode);
+	if (ret)
+		inode_dec_link_count(inode);
+	iput(inode);
+
+	return ret;
+}
+
+static int btrfs_rename(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_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);
+	u64 index = 0;
+	int ret;
+	u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
+	bool log_pinned = false;
+	struct btrfs_log_ctx ctx;
+	bool sync_log = false;
+	bool commit_transaction = false;
+
+	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;
+
+
+	/* check for collisions, even if the  name isn't there */
+	ret = btrfs_check_dir_item_collision(dest, new_dir->i_ino,
+			     new_dentry->d_name.name,
+			     new_dentry->d_name.len);
+
+	if (ret) {
+		if (ret == -EEXIST) {
+			/* we shouldn't get
+			 * eexist without a new_inode */
+			if (WARN_ON(!new_inode)) {
+				return ret;
+			}
+		} else {
+			/* maybe -EOVERFLOW */
+			return ret;
+		}
+	}
+	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);
+
+	/* close the racy window with snapshot create/destroy ioctl */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+		down_read(&fs_info->subvol_sem);
+	/*
+	 * We want to reserve the absolute worst case amount of items.  So if
+	 * both inodes are subvols and we need to unlink them then that would
+	 * require 4 item modifications, but if they are both normal inodes it
+	 * would require 5 item modifications, so we'll assume they are normal
+	 * inodes.  So 5 * 2 is 10, plus 1 for the new link, so 11 total items
+	 * should cover the worst case number of items we'll modify.
+	 * If our rename has the whiteout flag, we need more 5 units for the
+	 * new inode (1 inode item, 1 inode ref, 2 dir items and 1 xattr item
+	 * when selinux is enabled).
+	 */
+	trans_num_items = 11;
+	if (flags & RENAME_WHITEOUT)
+		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)
+		btrfs_record_root_in_trans(trans, dest);
+
+	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(fs_info, trans);
+	} else {
+		btrfs_pin_log_trans(root);
+		log_pinned = true;
+		ret = btrfs_insert_inode_ref(trans, dest,
+					     new_dentry->d_name.name,
+					     new_dentry->d_name.len,
+					     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);
+	old_dir->i_ctime = old_dir->i_mtime =
+	new_dir->i_ctime = new_dir->i_mtime =
+	old_inode->i_ctime = current_time(old_dir);
+
+	if (old_dentry->d_parent != new_dentry->d_parent)
+		btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
+				BTRFS_I(old_inode), 1);
+
+	if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		ret = btrfs_unlink_subvol(trans, old_dir, old_dentry);
+	} else {
+		ret = __btrfs_unlink_inode(trans, root, BTRFS_I(old_dir),
+					BTRFS_I(d_inode(old_dentry)),
+					old_dentry->d_name.name,
+					old_dentry->d_name.len);
+		if (!ret)
+			ret = btrfs_update_inode(trans, root, old_inode);
+	}
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	if (new_inode) {
+		inode_inc_iversion(new_inode);
+		new_inode->i_ctime = current_time(new_inode);
+		if (unlikely(btrfs_ino(BTRFS_I(new_inode)) ==
+			     BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
+			ret = btrfs_unlink_subvol(trans, new_dir, new_dentry);
+			BUG_ON(new_inode->i_nlink == 0);
+		} else {
+			ret = btrfs_unlink_inode(trans, dest, BTRFS_I(new_dir),
+						 BTRFS_I(d_inode(new_dentry)),
+						 new_dentry->d_name.name,
+						 new_dentry->d_name.len);
+		}
+		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_dentry->d_name.name,
+			     new_dentry->d_name.len, 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 (log_pinned) {
+		struct dentry *parent = new_dentry->d_parent;
+
+		btrfs_init_log_ctx(&ctx, old_inode);
+		ret = btrfs_log_new_name(trans, BTRFS_I(old_inode),
+					 BTRFS_I(old_dir), parent,
+					 false, &ctx);
+		if (ret == BTRFS_NEED_LOG_SYNC)
+			sync_log = true;
+		else if (ret == BTRFS_NEED_TRANS_COMMIT)
+			commit_transaction = true;
+		ret = 0;
+		btrfs_end_log_trans(root);
+		log_pinned = false;
+	}
+
+	if (flags & RENAME_WHITEOUT) {
+		ret = btrfs_whiteout_for_rename(trans, root, old_dir,
+						old_dentry);
+
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	}
+out_fail:
+	/*
+	 * If we have pinned the log and an error happened, we unpin tasks
+	 * trying to sync the log and force them to fallback to a transaction
+	 * commit if the log currently contains any of the inodes involved in
+	 * this rename operation (to ensure we do not persist a log with an
+	 * inconsistent state for any of these inodes or leading to any
+	 * inconsistencies when replayed). If the transaction was aborted, the
+	 * abortion reason is propagated to userspace when attempting to commit
+	 * the transaction. If the log does not contain any of these inodes, we
+	 * allow the tasks to sync it.
+	 */
+	if (ret && log_pinned) {
+		if (btrfs_inode_in_log(BTRFS_I(old_dir), fs_info->generation) ||
+		    btrfs_inode_in_log(BTRFS_I(new_dir), fs_info->generation) ||
+		    btrfs_inode_in_log(BTRFS_I(old_inode), fs_info->generation) ||
+		    (new_inode &&
+		     btrfs_inode_in_log(BTRFS_I(new_inode), fs_info->generation)))
+			btrfs_set_log_full_commit(fs_info, trans);
+
+		btrfs_end_log_trans(root);
+		log_pinned = false;
+	}
+	if (!ret && sync_log) {
+		ret = btrfs_sync_log(trans, BTRFS_I(old_inode)->root, &ctx);
+		if (ret)
+			commit_transaction = true;
+	} else if (sync_log) {
+		mutex_lock(&root->log_mutex);
+		list_del(&ctx.list);
+		mutex_unlock(&root->log_mutex);
+	}
+	if (commit_transaction) {
+		ret = btrfs_commit_transaction(trans);
+	} else {
+		int ret2;
+
+		ret2 = btrfs_end_transaction(trans);
+		ret = ret ? ret : ret2;
+	}
+out_notrans:
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+		up_read(&fs_info->subvol_sem);
+
+	return ret;
+}
+
+static int btrfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
+			 struct inode *new_dir, struct dentry *new_dentry,
+			 unsigned int flags)
+{
+	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
+		return -EINVAL;
+
+	if (flags & RENAME_EXCHANGE)
+		return btrfs_rename_exchange(old_dir, old_dentry, new_dir,
+					  new_dentry);
+
+	return btrfs_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
+}
+
+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;
+	WARN_ON_ONCE(!inode);
+	btrfs_init_work(&work->work, btrfs_flush_delalloc_helper,
+			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, int nr, bool snapshot)
+{
+	struct btrfs_inode *binode;
+	struct inode *inode;
+	struct btrfs_delalloc_work *work, *next;
+	struct list_head works;
+	struct list_head splice;
+	int ret = 0;
+
+	INIT_LIST_HEAD(&works);
+	INIT_LIST_HEAD(&splice);
+
+	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);
+		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);
+		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);
+		ret++;
+		if (nr != -1 && ret >= nr)
+			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)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+
+	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
+		return -EROFS;
+
+	ret = start_delalloc_inodes(root, -1, true);
+	if (ret > 0)
+		ret = 0;
+	return ret;
+}
+
+int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, int nr)
+{
+	struct btrfs_root *root;
+	struct list_head splice;
+	int ret;
+
+	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
+		return -EROFS;
+
+	INIT_LIST_HEAD(&splice);
+
+	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) && nr) {
+		root = list_first_entry(&splice, struct btrfs_root,
+					delalloc_root);
+		root = btrfs_grab_fs_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, nr, false);
+		btrfs_put_fs_root(root);
+		if (ret < 0)
+			goto out;
+
+		if (nr != -1) {
+			nr -= ret;
+			WARN_ON(nr < 0);
+		}
+		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 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 = NULL;
+	int err;
+	u64 objectid;
+	u64 index = 0;
+	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;
+
+	/*
+	 * 2 items for inode item and ref
+	 * 2 items for dir items
+	 * 1 item for updating parent inode item
+	 * 1 item for the inline extent item
+	 * 1 item for xattr if selinux is on
+	 */
+	trans = btrfs_start_transaction(root, 7);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	err = btrfs_find_free_ino(root, &objectid);
+	if (err)
+		goto out_unlock;
+
+	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
+				dentry->d_name.len, btrfs_ino(BTRFS_I(dir)),
+				objectid, S_IFLNK|S_IRWXUGO, &index);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		inode = NULL;
+		goto out_unlock;
+	}
+
+	/*
+	* If the active LSM wants to access the inode during
+	* d_instantiate it needs these. Smack checks to see
+	* if the filesystem supports xattrs by looking at the
+	* ops vector.
+	*/
+	inode->i_fop = &btrfs_file_operations;
+	inode->i_op = &btrfs_file_inode_operations;
+	inode->i_mapping->a_ops = &btrfs_aops;
+	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
+
+	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
+	if (err)
+		goto out_unlock;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+	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_free_path(path);
+		goto out_unlock;
+	}
+	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(leaf);
+	btrfs_free_path(path);
+
+	inode->i_op = &btrfs_symlink_inode_operations;
+	inode_nohighmem(inode);
+	inode->i_mapping->a_ops = &btrfs_symlink_aops;
+	inode_set_bytes(inode, name_len);
+	btrfs_i_size_write(BTRFS_I(inode), name_len);
+	err = btrfs_update_inode(trans, root, inode);
+	/*
+	 * Last step, add directory indexes for our symlink inode. This is the
+	 * last step to avoid extra cleanup of these indexes if an error happens
+	 * elsewhere above.
+	 */
+	if (!err)
+		err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry,
+				BTRFS_I(inode), 0, index);
+	if (err)
+		goto out_unlock;
+
+	d_instantiate_new(dentry, inode);
+
+out_unlock:
+	btrfs_end_transaction(trans);
+	if (err && inode) {
+		inode_dec_link_count(inode);
+		discard_new_inode(inode);
+	}
+	btrfs_btree_balance_dirty(fs_info);
+	return err;
+}
+
+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_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	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) {
+		if (own_trans) {
+			trans = btrfs_start_transaction(root, 3);
+			if (IS_ERR(trans)) {
+				ret = PTR_ERR(trans);
+				break;
+			}
+		}
+
+		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) {
+			if (own_trans)
+				btrfs_end_transaction(trans);
+			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;
+		btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+
+		last_alloc = ins.offset;
+		ret = insert_reserved_file_extent(trans, inode,
+						  cur_offset, ins.objectid,
+						  ins.offset, ins.offset,
+						  ins.offset, 0, 0, 0,
+						  BTRFS_FILE_EXTENT_PREALLOC);
+		if (ret) {
+			btrfs_free_reserved_extent(fs_info, ins.objectid,
+						   ins.offset, 0);
+			btrfs_abort_transaction(trans, ret);
+			if (own_trans)
+				btrfs_end_transaction(trans);
+			break;
+		}
+
+		btrfs_drop_extent_cache(BTRFS_I(inode), cur_offset,
+					cur_offset + ins.offset -1, 0);
+
+		em = alloc_extent_map();
+		if (!em) {
+			set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
+				&BTRFS_I(inode)->runtime_flags);
+			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;
+		em->bdev = fs_info->fs_devices->latest_bdev;
+		set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
+		em->generation = trans->transid;
+
+		while (1) {
+			write_lock(&em_tree->lock);
+			ret = add_extent_mapping(em_tree, em, 1);
+			write_unlock(&em_tree->lock);
+			if (ret != -EEXIST)
+				break;
+			btrfs_drop_extent_cache(BTRFS_I(inode), cur_offset,
+						cur_offset + ins.offset - 1,
+						0);
+		}
+		free_extent_map(em);
+next:
+		num_bytes -= ins.offset;
+		cur_offset += ins.offset;
+		*alloc_hint = ins.objectid + ins.offset;
+
+		inode_inc_iversion(inode);
+		inode->i_ctime = current_time(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_ordered_update_i_size(inode, i_size, NULL);
+		}
+
+		ret = btrfs_update_inode(trans, root, inode);
+
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			if (own_trans)
+				btrfs_end_transaction(trans);
+			break;
+		}
+
+		if (own_trans)
+			btrfs_end_transaction(trans);
+	}
+	if (clear_offset < end)
+		btrfs_free_reserved_data_space(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_set_page_dirty(struct page *page)
+{
+	return __set_page_dirty_nobuffers(page);
+}
+
+static int btrfs_permission(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(inode, mask);
+}
+
+static int btrfs_tmpfile(struct inode *dir, struct dentry *dentry, 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 = NULL;
+	u64 objectid;
+	u64 index;
+	int ret = 0;
+
+	/*
+	 * 5 units required for adding orphan entry
+	 */
+	trans = btrfs_start_transaction(root, 5);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	ret = btrfs_find_free_ino(root, &objectid);
+	if (ret)
+		goto out;
+
+	inode = btrfs_new_inode(trans, root, dir, NULL, 0,
+			btrfs_ino(BTRFS_I(dir)), objectid, mode, &index);
+	if (IS_ERR(inode)) {
+		ret = PTR_ERR(inode);
+		inode = NULL;
+		goto out;
+	}
+
+	inode->i_fop = &btrfs_file_operations;
+	inode->i_op = &btrfs_file_inode_operations;
+
+	inode->i_mapping->a_ops = &btrfs_aops;
+	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
+
+	ret = btrfs_init_inode_security(trans, inode, dir, NULL);
+	if (ret)
+		goto out;
+
+	ret = btrfs_update_inode(trans, root, inode);
+	if (ret)
+		goto out;
+	ret = btrfs_orphan_add(trans, BTRFS_I(inode));
+	if (ret)
+		goto out;
+
+	/*
+	 * We set number of links to 0 in btrfs_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);
+	d_tmpfile(dentry, inode);
+	unlock_new_inode(inode);
+	mark_inode_dirty(inode);
+out:
+	btrfs_end_transaction(trans);
+	if (ret && inode)
+		discard_new_inode(inode);
+	btrfs_btree_balance_dirty(fs_info);
+	return ret;
+}
+
+__attribute__((const))
+static int btrfs_readpage_io_failed_hook(struct page *page, int failed_mirror)
+{
+	return -EAGAIN;
+}
+
+static void btrfs_check_extent_io_range(void *private_data, const char *caller,
+					u64 start, u64 end)
+{
+	struct inode *inode = private_data;
+	u64 isize;
+
+	isize = i_size_read(inode);
+	if (end >= PAGE_SIZE && (end % 2) == 0 && end != isize - 1) {
+		btrfs_debug_rl(BTRFS_I(inode)->root->fs_info,
+		    "%s: ino %llu isize %llu odd range [%llu,%llu]",
+			caller, btrfs_ino(BTRFS_I(inode)), isize, start, end);
+	}
+}
+
+void btrfs_set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	struct inode *inode = tree->private_data;
+	unsigned long index = start >> PAGE_SHIFT;
+	unsigned long end_index = end >> PAGE_SHIFT;
+	struct page *page;
+
+	while (index <= end_index) {
+		page = find_get_page(inode->i_mapping, index);
+		ASSERT(page); /* Pages should be in the extent_io_tree */
+		set_page_writeback(page);
+		put_page(page);
+		index++;
+	}
+}
+
+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_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+	.tmpfile        = btrfs_tmpfile,
+};
+static const struct inode_operations btrfs_dir_ro_inode_operations = {
+	.lookup		= btrfs_lookup,
+	.permission	= btrfs_permission,
+	.update_time	= btrfs_update_time,
+};
+
+static const struct file_operations btrfs_dir_file_operations = {
+	.llseek		= generic_file_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,
+};
+
+static const struct extent_io_ops btrfs_extent_io_ops = {
+	/* mandatory callbacks */
+	.submit_bio_hook = btrfs_submit_bio_hook,
+	.readpage_end_io_hook = btrfs_readpage_end_io_hook,
+	.readpage_io_failed_hook = btrfs_readpage_io_failed_hook,
+
+	/* optional callbacks */
+	.writepage_end_io_hook = btrfs_writepage_end_io_hook,
+	.writepage_start_hook = btrfs_writepage_start_hook,
+	.set_bit_hook = btrfs_set_bit_hook,
+	.clear_bit_hook = btrfs_clear_bit_hook,
+	.merge_extent_hook = btrfs_merge_extent_hook,
+	.split_extent_hook = btrfs_split_extent_hook,
+	.check_extent_io_range = btrfs_check_extent_io_range,
+};
+
+/*
+ * 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 = {
+	.readpage	= btrfs_readpage,
+	.writepage	= btrfs_writepage,
+	.writepages	= btrfs_writepages,
+	.readpages	= btrfs_readpages,
+	.direct_IO	= btrfs_direct_IO,
+	.invalidatepage = btrfs_invalidatepage,
+	.releasepage	= btrfs_releasepage,
+	.set_page_dirty	= btrfs_set_page_dirty,
+	.error_remove_page = generic_error_remove_page,
+};
+
+static const struct address_space_operations btrfs_symlink_aops = {
+	.readpage	= btrfs_readpage,
+	.writepage	= btrfs_writepage,
+	.invalidatepage = btrfs_invalidatepage,
+	.releasepage	= btrfs_releasepage,
+};
+
+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_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+};
+static const struct inode_operations btrfs_special_inode_operations = {
+	.getattr	= btrfs_getattr,
+	.setattr	= btrfs_setattr,
+	.permission	= btrfs_permission,
+	.listxattr	= btrfs_listxattr,
+	.get_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,
+};