Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 1304 insertions, 0 deletions

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
new file mode 100644
index 000000000..14478da87
--- /dev/null
+++ b/fs/btrfs/file-item.c
@@ -0,0 +1,1304 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ */
+
+#include <linux/bio.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/sched/mm.h>
+#include <crypto/hash.h>
+#include "misc.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "volumes.h"
+#include "print-tree.h"
+#include "compression.h"
+
+#define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
+				   sizeof(struct btrfs_item) * 2) / \
+				  size) - 1))
+
+#define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
+				       PAGE_SIZE))
+
+/**
+ * Set inode's size according to filesystem options
+ *
+ * @inode:      inode we want to update the disk_i_size for
+ * @new_i_size: i_size we want to set to, 0 if we use i_size
+ *
+ * With NO_HOLES set this simply sets the disk_is_size to whatever i_size_read()
+ * returns as it is perfectly fine with a file that has holes without hole file
+ * extent items.
+ *
+ * However without NO_HOLES we need to only return the area that is contiguous
+ * from the 0 offset of the file.  Otherwise we could end up adjust i_size up
+ * to an extent that has a gap in between.
+ *
+ * Finally new_i_size should only be set in the case of truncate where we're not
+ * ready to use i_size_read() as the limiter yet.
+ */
+void btrfs_inode_safe_disk_i_size_write(struct btrfs_inode *inode, u64 new_i_size)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 start, end, i_size;
+	int ret;
+
+	spin_lock(&inode->lock);
+	i_size = new_i_size ?: i_size_read(&inode->vfs_inode);
+	if (btrfs_fs_incompat(fs_info, NO_HOLES)) {
+		inode->disk_i_size = i_size;
+		goto out_unlock;
+	}
+
+	ret = find_contiguous_extent_bit(&inode->file_extent_tree, 0, &start,
+					 &end, EXTENT_DIRTY);
+	if (!ret && start == 0)
+		i_size = min(i_size, end + 1);
+	else
+		i_size = 0;
+	inode->disk_i_size = i_size;
+out_unlock:
+	spin_unlock(&inode->lock);
+}
+
+/**
+ * Mark range within a file as having a new extent inserted
+ *
+ * @inode: inode being modified
+ * @start: start file offset of the file extent we've inserted
+ * @len:   logical length of the file extent item
+ *
+ * Call when we are inserting a new file extent where there was none before.
+ * Does not need to call this in the case where we're replacing an existing file
+ * extent, however if not sure it's fine to call this multiple times.
+ *
+ * The start and len must match the file extent item, so thus must be sectorsize
+ * aligned.
+ */
+int btrfs_inode_set_file_extent_range(struct btrfs_inode *inode, u64 start,
+				      u64 len)
+{
+	if (len == 0)
+		return 0;
+
+	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize));
+
+	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
+		return 0;
+	return set_extent_bits(&inode->file_extent_tree, start, start + len - 1,
+			       EXTENT_DIRTY);
+}
+
+/**
+ * Marks an inode range as not having a backing extent
+ *
+ * @inode: inode being modified
+ * @start: start file offset of the file extent we've inserted
+ * @len:   logical length of the file extent item
+ *
+ * Called when we drop a file extent, for example when we truncate.  Doesn't
+ * need to be called for cases where we're replacing a file extent, like when
+ * we've COWed a file extent.
+ *
+ * The start and len must match the file extent item, so thus must be sectorsize
+ * aligned.
+ */
+int btrfs_inode_clear_file_extent_range(struct btrfs_inode *inode, u64 start,
+					u64 len)
+{
+	if (len == 0)
+		return 0;
+
+	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize) ||
+	       len == (u64)-1);
+
+	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
+		return 0;
+	return clear_extent_bit(&inode->file_extent_tree, start,
+				start + len - 1, EXTENT_DIRTY, NULL);
+}
+
+static inline u32 max_ordered_sum_bytes(struct btrfs_fs_info *fs_info,
+					u16 csum_size)
+{
+	u32 ncsums = (PAGE_SIZE - sizeof(struct btrfs_ordered_sum)) / csum_size;
+
+	return ncsums * fs_info->sectorsize;
+}
+
+/*
+ * Calculate the total size needed to allocate for an ordered sum structure
+ * spanning @bytes in the file.
+ */
+static int btrfs_ordered_sum_size(struct btrfs_fs_info *fs_info, unsigned long bytes)
+{
+	int num_sectors = (int)DIV_ROUND_UP(bytes, fs_info->sectorsize);
+
+	return sizeof(struct btrfs_ordered_sum) + num_sectors * fs_info->csum_size;
+}
+
+int btrfs_insert_hole_extent(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root,
+			     u64 objectid, u64 pos, u64 num_bytes)
+{
+	int ret = 0;
+	struct btrfs_file_extent_item *item;
+	struct btrfs_key file_key;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	file_key.objectid = objectid;
+	file_key.offset = pos;
+	file_key.type = BTRFS_EXTENT_DATA_KEY;
+
+	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
+				      sizeof(*item));
+	if (ret < 0)
+		goto out;
+	BUG_ON(ret); /* Can't happen */
+	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, 0);
+	btrfs_set_file_extent_disk_num_bytes(leaf, item, 0);
+	btrfs_set_file_extent_offset(leaf, item, 0);
+	btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
+	btrfs_set_file_extent_ram_bytes(leaf, item, num_bytes);
+	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, 0);
+	btrfs_set_file_extent_encryption(leaf, item, 0);
+	btrfs_set_file_extent_other_encoding(leaf, item, 0);
+
+	btrfs_mark_buffer_dirty(leaf);
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static struct btrfs_csum_item *
+btrfs_lookup_csum(struct btrfs_trans_handle *trans,
+		  struct btrfs_root *root,
+		  struct btrfs_path *path,
+		  u64 bytenr, int cow)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+	struct btrfs_key file_key;
+	struct btrfs_key found_key;
+	struct btrfs_csum_item *item;
+	struct extent_buffer *leaf;
+	u64 csum_offset = 0;
+	const u32 csum_size = fs_info->csum_size;
+	int csums_in_item;
+
+	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+	file_key.offset = bytenr;
+	file_key.type = BTRFS_EXTENT_CSUM_KEY;
+	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
+	if (ret < 0)
+		goto fail;
+	leaf = path->nodes[0];
+	if (ret > 0) {
+		ret = 1;
+		if (path->slots[0] == 0)
+			goto fail;
+		path->slots[0]--;
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
+			goto fail;
+
+		csum_offset = (bytenr - found_key.offset) >>
+				fs_info->sectorsize_bits;
+		csums_in_item = btrfs_item_size(leaf, path->slots[0]);
+		csums_in_item /= csum_size;
+
+		if (csum_offset == csums_in_item) {
+			ret = -EFBIG;
+			goto fail;
+		} else if (csum_offset > csums_in_item) {
+			goto fail;
+		}
+	}
+	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
+	item = (struct btrfs_csum_item *)((unsigned char *)item +
+					  csum_offset * csum_size);
+	return item;
+fail:
+	if (ret > 0)
+		ret = -ENOENT;
+	return ERR_PTR(ret);
+}
+
+int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root,
+			     struct btrfs_path *path, u64 objectid,
+			     u64 offset, int mod)
+{
+	struct btrfs_key file_key;
+	int ins_len = mod < 0 ? -1 : 0;
+	int cow = mod != 0;
+
+	file_key.objectid = objectid;
+	file_key.offset = offset;
+	file_key.type = BTRFS_EXTENT_DATA_KEY;
+
+	return btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
+}
+
+/*
+ * Find checksums for logical bytenr range [disk_bytenr, disk_bytenr + len) and
+ * estore the result to @dst.
+ *
+ * Return >0 for the number of sectors we found.
+ * Return 0 for the range [disk_bytenr, disk_bytenr + sectorsize) has no csum
+ * for it. Caller may want to try next sector until one range is hit.
+ * Return <0 for fatal error.
+ */
+static int search_csum_tree(struct btrfs_fs_info *fs_info,
+			    struct btrfs_path *path, u64 disk_bytenr,
+			    u64 len, u8 *dst)
+{
+	struct btrfs_root *csum_root;
+	struct btrfs_csum_item *item = NULL;
+	struct btrfs_key key;
+	const u32 sectorsize = fs_info->sectorsize;
+	const u32 csum_size = fs_info->csum_size;
+	u32 itemsize;
+	int ret;
+	u64 csum_start;
+	u64 csum_len;
+
+	ASSERT(IS_ALIGNED(disk_bytenr, sectorsize) &&
+	       IS_ALIGNED(len, sectorsize));
+
+	/* Check if the current csum item covers disk_bytenr */
+	if (path->nodes[0]) {
+		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				      struct btrfs_csum_item);
+		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+		itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
+
+		csum_start = key.offset;
+		csum_len = (itemsize / csum_size) * sectorsize;
+
+		if (in_range(disk_bytenr, csum_start, csum_len))
+			goto found;
+	}
+
+	/* Current item doesn't contain the desired range, search again */
+	btrfs_release_path(path);
+	csum_root = btrfs_csum_root(fs_info, disk_bytenr);
+	item = btrfs_lookup_csum(NULL, csum_root, path, disk_bytenr, 0);
+	if (IS_ERR(item)) {
+		ret = PTR_ERR(item);
+		goto out;
+	}
+	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+	itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
+
+	csum_start = key.offset;
+	csum_len = (itemsize / csum_size) * sectorsize;
+	ASSERT(in_range(disk_bytenr, csum_start, csum_len));
+
+found:
+	ret = (min(csum_start + csum_len, disk_bytenr + len) -
+		   disk_bytenr) >> fs_info->sectorsize_bits;
+	read_extent_buffer(path->nodes[0], dst, (unsigned long)item,
+			ret * csum_size);
+out:
+	if (ret == -ENOENT || ret == -EFBIG)
+		ret = 0;
+	return ret;
+}
+
+/*
+ * Locate the file_offset of @cur_disk_bytenr of a @bio.
+ *
+ * Bio of btrfs represents read range of
+ * [bi_sector << 9, bi_sector << 9 + bi_size).
+ * Knowing this, we can iterate through each bvec to locate the page belong to
+ * @cur_disk_bytenr and get the file offset.
+ *
+ * @inode is used to determine if the bvec page really belongs to @inode.
+ *
+ * Return 0 if we can't find the file offset
+ * Return >0 if we find the file offset and restore it to @file_offset_ret
+ */
+static int search_file_offset_in_bio(struct bio *bio, struct inode *inode,
+				     u64 disk_bytenr, u64 *file_offset_ret)
+{
+	struct bvec_iter iter;
+	struct bio_vec bvec;
+	u64 cur = bio->bi_iter.bi_sector << SECTOR_SHIFT;
+	int ret = 0;
+
+	bio_for_each_segment(bvec, bio, iter) {
+		struct page *page = bvec.bv_page;
+
+		if (cur > disk_bytenr)
+			break;
+		if (cur + bvec.bv_len <= disk_bytenr) {
+			cur += bvec.bv_len;
+			continue;
+		}
+		ASSERT(in_range(disk_bytenr, cur, bvec.bv_len));
+		if (page->mapping && page->mapping->host &&
+		    page->mapping->host == inode) {
+			ret = 1;
+			*file_offset_ret = page_offset(page) + bvec.bv_offset +
+					   disk_bytenr - cur;
+			break;
+		}
+	}
+	return ret;
+}
+
+/**
+ * Lookup the checksum for the read bio in csum tree.
+ *
+ * @inode: inode that the bio is for.
+ * @bio: bio to look up.
+ * @dst: Buffer of size nblocks * btrfs_super_csum_size() used to return
+ *       checksum (nblocks = bio->bi_iter.bi_size / fs_info->sectorsize). If
+ *       NULL, the checksum buffer is allocated and returned in
+ *       btrfs_bio(bio)->csum instead.
+ *
+ * Return: BLK_STS_RESOURCE if allocating memory fails, BLK_STS_OK otherwise.
+ */
+blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct btrfs_bio *bbio = NULL;
+	struct btrfs_path *path;
+	const u32 sectorsize = fs_info->sectorsize;
+	const u32 csum_size = fs_info->csum_size;
+	u32 orig_len = bio->bi_iter.bi_size;
+	u64 orig_disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
+	u64 cur_disk_bytenr;
+	u8 *csum;
+	const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;
+	int count = 0;
+	blk_status_t ret = BLK_STS_OK;
+
+	if ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) ||
+	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
+		return BLK_STS_OK;
+
+	/*
+	 * This function is only called for read bio.
+	 *
+	 * This means two things:
+	 * - All our csums should only be in csum tree
+	 *   No ordered extents csums, as ordered extents are only for write
+	 *   path.
+	 * - No need to bother any other info from bvec
+	 *   Since we're looking up csums, the only important info is the
+	 *   disk_bytenr and the length, which can be extracted from bi_iter
+	 *   directly.
+	 */
+	ASSERT(bio_op(bio) == REQ_OP_READ);
+	path = btrfs_alloc_path();
+	if (!path)
+		return BLK_STS_RESOURCE;
+
+	if (!dst) {
+		bbio = btrfs_bio(bio);
+
+		if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
+			bbio->csum = kmalloc_array(nblocks, csum_size, GFP_NOFS);
+			if (!bbio->csum) {
+				btrfs_free_path(path);
+				return BLK_STS_RESOURCE;
+			}
+		} else {
+			bbio->csum = bbio->csum_inline;
+		}
+		csum = bbio->csum;
+	} else {
+		csum = dst;
+	}
+
+	/*
+	 * If requested number of sectors is larger than one leaf can contain,
+	 * kick the readahead for csum tree.
+	 */
+	if (nblocks > fs_info->csums_per_leaf)
+		path->reada = READA_FORWARD;
+
+	/*
+	 * the free space stuff is only read when it hasn't been
+	 * updated in the current transaction.  So, we can safely
+	 * read from the commit root and sidestep a nasty deadlock
+	 * between reading the free space cache and updating the csum tree.
+	 */
+	if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
+		path->search_commit_root = 1;
+		path->skip_locking = 1;
+	}
+
+	for (cur_disk_bytenr = orig_disk_bytenr;
+	     cur_disk_bytenr < orig_disk_bytenr + orig_len;
+	     cur_disk_bytenr += (count * sectorsize)) {
+		u64 search_len = orig_disk_bytenr + orig_len - cur_disk_bytenr;
+		unsigned int sector_offset;
+		u8 *csum_dst;
+
+		/*
+		 * Although both cur_disk_bytenr and orig_disk_bytenr is u64,
+		 * we're calculating the offset to the bio start.
+		 *
+		 * Bio size is limited to UINT_MAX, thus unsigned int is large
+		 * enough to contain the raw result, not to mention the right
+		 * shifted result.
+		 */
+		ASSERT(cur_disk_bytenr - orig_disk_bytenr < UINT_MAX);
+		sector_offset = (cur_disk_bytenr - orig_disk_bytenr) >>
+				fs_info->sectorsize_bits;
+		csum_dst = csum + sector_offset * csum_size;
+
+		count = search_csum_tree(fs_info, path, cur_disk_bytenr,
+					 search_len, csum_dst);
+		if (count < 0) {
+			ret = errno_to_blk_status(count);
+			if (bbio)
+				btrfs_bio_free_csum(bbio);
+			break;
+		}
+
+		/*
+		 * We didn't find a csum for this range.  We need to make sure
+		 * we complain loudly about this, because we are not NODATASUM.
+		 *
+		 * However for the DATA_RELOC inode we could potentially be
+		 * relocating data extents for a NODATASUM inode, so the inode
+		 * itself won't be marked with NODATASUM, but the extent we're
+		 * copying is in fact NODATASUM.  If we don't find a csum we
+		 * assume this is the case.
+		 */
+		if (count == 0) {
+			memset(csum_dst, 0, csum_size);
+			count = 1;
+
+			if (BTRFS_I(inode)->root->root_key.objectid ==
+			    BTRFS_DATA_RELOC_TREE_OBJECTID) {
+				u64 file_offset;
+				int ret;
+
+				ret = search_file_offset_in_bio(bio, inode,
+						cur_disk_bytenr, &file_offset);
+				if (ret)
+					set_extent_bits(io_tree, file_offset,
+						file_offset + sectorsize - 1,
+						EXTENT_NODATASUM);
+			} else {
+				btrfs_warn_rl(fs_info,
+			"csum hole found for disk bytenr range [%llu, %llu)",
+				cur_disk_bytenr, cur_disk_bytenr + sectorsize);
+			}
+		}
+	}
+
+	btrfs_free_path(path);
+	return ret;
+}
+
+int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
+			     struct list_head *list, int search_commit,
+			     bool nowait)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_key key;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_ordered_sum *sums;
+	struct btrfs_csum_item *item;
+	LIST_HEAD(tmplist);
+	unsigned long offset;
+	int ret;
+	size_t size;
+	u64 csum_end;
+	const u32 csum_size = fs_info->csum_size;
+
+	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
+	       IS_ALIGNED(end + 1, fs_info->sectorsize));
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	path->nowait = nowait;
+	if (search_commit) {
+		path->skip_locking = 1;
+		path->reada = READA_FORWARD;
+		path->search_commit_root = 1;
+	}
+
+	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+	key.offset = start;
+	key.type = BTRFS_EXTENT_CSUM_KEY;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto fail;
+	if (ret > 0 && path->slots[0] > 0) {
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
+		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
+		    key.type == BTRFS_EXTENT_CSUM_KEY) {
+			offset = (start - key.offset) >> fs_info->sectorsize_bits;
+			if (offset * csum_size <
+			    btrfs_item_size(leaf, path->slots[0] - 1))
+				path->slots[0]--;
+		}
+	}
+
+	while (start <= end) {
+		leaf = path->nodes[0];
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto fail;
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+		    key.type != BTRFS_EXTENT_CSUM_KEY ||
+		    key.offset > end)
+			break;
+
+		if (key.offset > start)
+			start = key.offset;
+
+		size = btrfs_item_size(leaf, path->slots[0]);
+		csum_end = key.offset + (size / csum_size) * fs_info->sectorsize;
+		if (csum_end <= start) {
+			path->slots[0]++;
+			continue;
+		}
+
+		csum_end = min(csum_end, end + 1);
+		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				      struct btrfs_csum_item);
+		while (start < csum_end) {
+			size = min_t(size_t, csum_end - start,
+				     max_ordered_sum_bytes(fs_info, csum_size));
+			sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
+				       GFP_NOFS);
+			if (!sums) {
+				ret = -ENOMEM;
+				goto fail;
+			}
+
+			sums->bytenr = start;
+			sums->len = size;
+
+			offset = (start - key.offset) >> fs_info->sectorsize_bits;
+			offset *= csum_size;
+			size >>= fs_info->sectorsize_bits;
+
+			read_extent_buffer(path->nodes[0],
+					   sums->sums,
+					   ((unsigned long)item) + offset,
+					   csum_size * size);
+
+			start += fs_info->sectorsize * size;
+			list_add_tail(&sums->list, &tmplist);
+		}
+		path->slots[0]++;
+	}
+	ret = 0;
+fail:
+	while (ret < 0 && !list_empty(&tmplist)) {
+		sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
+		list_del(&sums->list);
+		kfree(sums);
+	}
+	list_splice_tail(&tmplist, list);
+
+	btrfs_free_path(path);
+	return ret;
+}
+
+/**
+ * Calculate checksums of the data contained inside a bio
+ *
+ * @inode:	 Owner of the data inside the bio
+ * @bio:	 Contains the data to be checksummed
+ * @offset:      If (u64)-1, @bio may contain discontiguous bio vecs, so the
+ *               file offsets are determined from the page offsets in the bio.
+ *               Otherwise, this is the starting file offset of the bio vecs in
+ *               @bio, which must be contiguous.
+ * @one_ordered: If true, @bio only refers to one ordered extent.
+ */
+blk_status_t btrfs_csum_one_bio(struct btrfs_inode *inode, struct bio *bio,
+				u64 offset, bool one_ordered)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
+	struct btrfs_ordered_sum *sums;
+	struct btrfs_ordered_extent *ordered = NULL;
+	const bool use_page_offsets = (offset == (u64)-1);
+	char *data;
+	struct bvec_iter iter;
+	struct bio_vec bvec;
+	int index;
+	unsigned int blockcount;
+	unsigned long total_bytes = 0;
+	unsigned long this_sum_bytes = 0;
+	int i;
+	unsigned nofs_flag;
+
+	nofs_flag = memalloc_nofs_save();
+	sums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
+		       GFP_KERNEL);
+	memalloc_nofs_restore(nofs_flag);
+
+	if (!sums)
+		return BLK_STS_RESOURCE;
+
+	sums->len = bio->bi_iter.bi_size;
+	INIT_LIST_HEAD(&sums->list);
+
+	sums->bytenr = bio->bi_iter.bi_sector << 9;
+	index = 0;
+
+	shash->tfm = fs_info->csum_shash;
+
+	bio_for_each_segment(bvec, bio, iter) {
+		if (use_page_offsets)
+			offset = page_offset(bvec.bv_page) + bvec.bv_offset;
+
+		if (!ordered) {
+			ordered = btrfs_lookup_ordered_extent(inode, offset);
+			/*
+			 * The bio range is not covered by any ordered extent,
+			 * must be a code logic error.
+			 */
+			if (unlikely(!ordered)) {
+				WARN(1, KERN_WARNING
+			"no ordered extent for root %llu ino %llu offset %llu\n",
+				     inode->root->root_key.objectid,
+				     btrfs_ino(inode), offset);
+				kvfree(sums);
+				return BLK_STS_IOERR;
+			}
+		}
+
+		blockcount = BTRFS_BYTES_TO_BLKS(fs_info,
+						 bvec.bv_len + fs_info->sectorsize
+						 - 1);
+
+		for (i = 0; i < blockcount; i++) {
+			if (!one_ordered &&
+			    !in_range(offset, ordered->file_offset,
+				      ordered->num_bytes)) {
+				unsigned long bytes_left;
+
+				sums->len = this_sum_bytes;
+				this_sum_bytes = 0;
+				btrfs_add_ordered_sum(ordered, sums);
+				btrfs_put_ordered_extent(ordered);
+
+				bytes_left = bio->bi_iter.bi_size - total_bytes;
+
+				nofs_flag = memalloc_nofs_save();
+				sums = kvzalloc(btrfs_ordered_sum_size(fs_info,
+						      bytes_left), GFP_KERNEL);
+				memalloc_nofs_restore(nofs_flag);
+				if (!sums)
+					return BLK_STS_RESOURCE;
+
+				sums->len = bytes_left;
+				ordered = btrfs_lookup_ordered_extent(inode,
+								offset);
+				ASSERT(ordered); /* Logic error */
+				sums->bytenr = (bio->bi_iter.bi_sector << 9)
+					+ total_bytes;
+				index = 0;
+			}
+
+			data = bvec_kmap_local(&bvec);
+			crypto_shash_digest(shash,
+					    data + (i * fs_info->sectorsize),
+					    fs_info->sectorsize,
+					    sums->sums + index);
+			kunmap_local(data);
+			index += fs_info->csum_size;
+			offset += fs_info->sectorsize;
+			this_sum_bytes += fs_info->sectorsize;
+			total_bytes += fs_info->sectorsize;
+		}
+
+	}
+	this_sum_bytes = 0;
+	btrfs_add_ordered_sum(ordered, sums);
+	btrfs_put_ordered_extent(ordered);
+	return 0;
+}
+
+/*
+ * helper function for csum removal, this expects the
+ * key to describe the csum pointed to by the path, and it expects
+ * the csum to overlap the range [bytenr, len]
+ *
+ * The csum should not be entirely contained in the range and the
+ * range should not be entirely contained in the csum.
+ *
+ * This calls btrfs_truncate_item with the correct args based on the
+ * overlap, and fixes up the key as required.
+ */
+static noinline void truncate_one_csum(struct btrfs_fs_info *fs_info,
+				       struct btrfs_path *path,
+				       struct btrfs_key *key,
+				       u64 bytenr, u64 len)
+{
+	struct extent_buffer *leaf;
+	const u32 csum_size = fs_info->csum_size;
+	u64 csum_end;
+	u64 end_byte = bytenr + len;
+	u32 blocksize_bits = fs_info->sectorsize_bits;
+
+	leaf = path->nodes[0];
+	csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
+	csum_end <<= blocksize_bits;
+	csum_end += key->offset;
+
+	if (key->offset < bytenr && csum_end <= end_byte) {
+		/*
+		 *         [ bytenr - len ]
+		 *         [   ]
+		 *   [csum     ]
+		 *   A simple truncate off the end of the item
+		 */
+		u32 new_size = (bytenr - key->offset) >> blocksize_bits;
+		new_size *= csum_size;
+		btrfs_truncate_item(path, new_size, 1);
+	} else if (key->offset >= bytenr && csum_end > end_byte &&
+		   end_byte > key->offset) {
+		/*
+		 *         [ bytenr - len ]
+		 *                 [ ]
+		 *                 [csum     ]
+		 * we need to truncate from the beginning of the csum
+		 */
+		u32 new_size = (csum_end - end_byte) >> blocksize_bits;
+		new_size *= csum_size;
+
+		btrfs_truncate_item(path, new_size, 0);
+
+		key->offset = end_byte;
+		btrfs_set_item_key_safe(fs_info, path, key);
+	} else {
+		BUG();
+	}
+}
+
+/*
+ * deletes the csum items from the csum tree for a given
+ * range of bytes.
+ */
+int btrfs_del_csums(struct btrfs_trans_handle *trans,
+		    struct btrfs_root *root, u64 bytenr, u64 len)
+{
+	struct btrfs_fs_info *fs_info = trans->fs_info;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	u64 end_byte = bytenr + len;
+	u64 csum_end;
+	struct extent_buffer *leaf;
+	int ret = 0;
+	const u32 csum_size = fs_info->csum_size;
+	u32 blocksize_bits = fs_info->sectorsize_bits;
+
+	ASSERT(root->root_key.objectid == BTRFS_CSUM_TREE_OBJECTID ||
+	       root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	while (1) {
+		key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+		key.offset = end_byte - 1;
+		key.type = BTRFS_EXTENT_CSUM_KEY;
+
+		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+		if (ret > 0) {
+			ret = 0;
+			if (path->slots[0] == 0)
+				break;
+			path->slots[0]--;
+		} else if (ret < 0) {
+			break;
+		}
+
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+		    key.type != BTRFS_EXTENT_CSUM_KEY) {
+			break;
+		}
+
+		if (key.offset >= end_byte)
+			break;
+
+		csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
+		csum_end <<= blocksize_bits;
+		csum_end += key.offset;
+
+		/* this csum ends before we start, we're done */
+		if (csum_end <= bytenr)
+			break;
+
+		/* delete the entire item, it is inside our range */
+		if (key.offset >= bytenr && csum_end <= end_byte) {
+			int del_nr = 1;
+
+			/*
+			 * Check how many csum items preceding this one in this
+			 * leaf correspond to our range and then delete them all
+			 * at once.
+			 */
+			if (key.offset > bytenr && path->slots[0] > 0) {
+				int slot = path->slots[0] - 1;
+
+				while (slot >= 0) {
+					struct btrfs_key pk;
+
+					btrfs_item_key_to_cpu(leaf, &pk, slot);
+					if (pk.offset < bytenr ||
+					    pk.type != BTRFS_EXTENT_CSUM_KEY ||
+					    pk.objectid !=
+					    BTRFS_EXTENT_CSUM_OBJECTID)
+						break;
+					path->slots[0] = slot;
+					del_nr++;
+					key.offset = pk.offset;
+					slot--;
+				}
+			}
+			ret = btrfs_del_items(trans, root, path,
+					      path->slots[0], del_nr);
+			if (ret)
+				break;
+			if (key.offset == bytenr)
+				break;
+		} else if (key.offset < bytenr && csum_end > end_byte) {
+			unsigned long offset;
+			unsigned long shift_len;
+			unsigned long item_offset;
+			/*
+			 *        [ bytenr - len ]
+			 *     [csum                ]
+			 *
+			 * Our bytes are in the middle of the csum,
+			 * we need to split this item and insert a new one.
+			 *
+			 * But we can't drop the path because the
+			 * csum could change, get removed, extended etc.
+			 *
+			 * The trick here is the max size of a csum item leaves
+			 * enough room in the tree block for a single
+			 * item header.  So, we split the item in place,
+			 * adding a new header pointing to the existing
+			 * bytes.  Then we loop around again and we have
+			 * a nicely formed csum item that we can neatly
+			 * truncate.
+			 */
+			offset = (bytenr - key.offset) >> blocksize_bits;
+			offset *= csum_size;
+
+			shift_len = (len >> blocksize_bits) * csum_size;
+
+			item_offset = btrfs_item_ptr_offset(leaf,
+							    path->slots[0]);
+
+			memzero_extent_buffer(leaf, item_offset + offset,
+					     shift_len);
+			key.offset = bytenr;
+
+			/*
+			 * btrfs_split_item returns -EAGAIN when the
+			 * item changed size or key
+			 */
+			ret = btrfs_split_item(trans, root, path, &key, offset);
+			if (ret && ret != -EAGAIN) {
+				btrfs_abort_transaction(trans, ret);
+				break;
+			}
+			ret = 0;
+
+			key.offset = end_byte - 1;
+		} else {
+			truncate_one_csum(fs_info, path, &key, bytenr, len);
+			if (key.offset < bytenr)
+				break;
+		}
+		btrfs_release_path(path);
+	}
+	btrfs_free_path(path);
+	return ret;
+}
+
+static int find_next_csum_offset(struct btrfs_root *root,
+				 struct btrfs_path *path,
+				 u64 *next_offset)
+{
+	const u32 nritems = btrfs_header_nritems(path->nodes[0]);
+	struct btrfs_key found_key;
+	int slot = path->slots[0] + 1;
+	int ret;
+
+	if (nritems == 0 || slot >= nritems) {
+		ret = btrfs_next_leaf(root, path);
+		if (ret < 0) {
+			return ret;
+		} else if (ret > 0) {
+			*next_offset = (u64)-1;
+			return 0;
+		}
+		slot = path->slots[0];
+	}
+
+	btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
+
+	if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+	    found_key.type != BTRFS_EXTENT_CSUM_KEY)
+		*next_offset = (u64)-1;
+	else
+		*next_offset = found_key.offset;
+
+	return 0;
+}
+
+int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root,
+			   struct btrfs_ordered_sum *sums)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_key file_key;
+	struct btrfs_key found_key;
+	struct btrfs_path *path;
+	struct btrfs_csum_item *item;
+	struct btrfs_csum_item *item_end;
+	struct extent_buffer *leaf = NULL;
+	u64 next_offset;
+	u64 total_bytes = 0;
+	u64 csum_offset;
+	u64 bytenr;
+	u32 ins_size;
+	int index = 0;
+	int found_next;
+	int ret;
+	const u32 csum_size = fs_info->csum_size;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+again:
+	next_offset = (u64)-1;
+	found_next = 0;
+	bytenr = sums->bytenr + total_bytes;
+	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+	file_key.offset = bytenr;
+	file_key.type = BTRFS_EXTENT_CSUM_KEY;
+
+	item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
+	if (!IS_ERR(item)) {
+		ret = 0;
+		leaf = path->nodes[0];
+		item_end = btrfs_item_ptr(leaf, path->slots[0],
+					  struct btrfs_csum_item);
+		item_end = (struct btrfs_csum_item *)((char *)item_end +
+			   btrfs_item_size(leaf, path->slots[0]));
+		goto found;
+	}
+	ret = PTR_ERR(item);
+	if (ret != -EFBIG && ret != -ENOENT)
+		goto out;
+
+	if (ret == -EFBIG) {
+		u32 item_size;
+		/* we found one, but it isn't big enough yet */
+		leaf = path->nodes[0];
+		item_size = btrfs_item_size(leaf, path->slots[0]);
+		if ((item_size / csum_size) >=
+		    MAX_CSUM_ITEMS(fs_info, csum_size)) {
+			/* already at max size, make a new one */
+			goto insert;
+		}
+	} else {
+		/* We didn't find a csum item, insert one. */
+		ret = find_next_csum_offset(root, path, &next_offset);
+		if (ret < 0)
+			goto out;
+		found_next = 1;
+		goto insert;
+	}
+
+	/*
+	 * At this point, we know the tree has a checksum item that ends at an
+	 * offset matching the start of the checksum range we want to insert.
+	 * We try to extend that item as much as possible and then add as many
+	 * checksums to it as they fit.
+	 *
+	 * First check if the leaf has enough free space for at least one
+	 * checksum. If it has go directly to the item extension code, otherwise
+	 * release the path and do a search for insertion before the extension.
+	 */
+	if (btrfs_leaf_free_space(leaf) >= csum_size) {
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		csum_offset = (bytenr - found_key.offset) >>
+			fs_info->sectorsize_bits;
+		goto extend_csum;
+	}
+
+	btrfs_release_path(path);
+	path->search_for_extension = 1;
+	ret = btrfs_search_slot(trans, root, &file_key, path,
+				csum_size, 1);
+	path->search_for_extension = 0;
+	if (ret < 0)
+		goto out;
+
+	if (ret > 0) {
+		if (path->slots[0] == 0)
+			goto insert;
+		path->slots[0]--;
+	}
+
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+	csum_offset = (bytenr - found_key.offset) >> fs_info->sectorsize_bits;
+
+	if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
+	    found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+	    csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
+		goto insert;
+	}
+
+extend_csum:
+	if (csum_offset == btrfs_item_size(leaf, path->slots[0]) /
+	    csum_size) {
+		int extend_nr;
+		u64 tmp;
+		u32 diff;
+
+		tmp = sums->len - total_bytes;
+		tmp >>= fs_info->sectorsize_bits;
+		WARN_ON(tmp < 1);
+		extend_nr = max_t(int, 1, tmp);
+
+		/*
+		 * A log tree can already have checksum items with a subset of
+		 * the checksums we are trying to log. This can happen after
+		 * doing a sequence of partial writes into prealloc extents and
+		 * fsyncs in between, with a full fsync logging a larger subrange
+		 * of an extent for which a previous fast fsync logged a smaller
+		 * subrange. And this happens in particular due to merging file
+		 * extent items when we complete an ordered extent for a range
+		 * covered by a prealloc extent - this is done at
+		 * btrfs_mark_extent_written().
+		 *
+		 * So if we try to extend the previous checksum item, which has
+		 * a range that ends at the start of the range we want to insert,
+		 * make sure we don't extend beyond the start offset of the next
+		 * checksum item. If we are at the last item in the leaf, then
+		 * forget the optimization of extending and add a new checksum
+		 * item - it is not worth the complexity of releasing the path,
+		 * getting the first key for the next leaf, repeat the btree
+		 * search, etc, because log trees are temporary anyway and it
+		 * would only save a few bytes of leaf space.
+		 */
+		if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
+			if (path->slots[0] + 1 >=
+			    btrfs_header_nritems(path->nodes[0])) {
+				ret = find_next_csum_offset(root, path, &next_offset);
+				if (ret < 0)
+					goto out;
+				found_next = 1;
+				goto insert;
+			}
+
+			ret = find_next_csum_offset(root, path, &next_offset);
+			if (ret < 0)
+				goto out;
+
+			tmp = (next_offset - bytenr) >> fs_info->sectorsize_bits;
+			if (tmp <= INT_MAX)
+				extend_nr = min_t(int, extend_nr, tmp);
+		}
+
+		diff = (csum_offset + extend_nr) * csum_size;
+		diff = min(diff,
+			   MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);
+
+		diff = diff - btrfs_item_size(leaf, path->slots[0]);
+		diff = min_t(u32, btrfs_leaf_free_space(leaf), diff);
+		diff /= csum_size;
+		diff *= csum_size;
+
+		btrfs_extend_item(path, diff);
+		ret = 0;
+		goto csum;
+	}
+
+insert:
+	btrfs_release_path(path);
+	csum_offset = 0;
+	if (found_next) {
+		u64 tmp;
+
+		tmp = sums->len - total_bytes;
+		tmp >>= fs_info->sectorsize_bits;
+		tmp = min(tmp, (next_offset - file_key.offset) >>
+					 fs_info->sectorsize_bits);
+
+		tmp = max_t(u64, 1, tmp);
+		tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
+		ins_size = csum_size * tmp;
+	} else {
+		ins_size = csum_size;
+	}
+	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
+				      ins_size);
+	if (ret < 0)
+		goto out;
+	if (WARN_ON(ret != 0))
+		goto out;
+	leaf = path->nodes[0];
+csum:
+	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
+	item_end = (struct btrfs_csum_item *)((unsigned char *)item +
+				      btrfs_item_size(leaf, path->slots[0]));
+	item = (struct btrfs_csum_item *)((unsigned char *)item +
+					  csum_offset * csum_size);
+found:
+	ins_size = (u32)(sums->len - total_bytes) >> fs_info->sectorsize_bits;
+	ins_size *= csum_size;
+	ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
+			      ins_size);
+	write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
+			    ins_size);
+
+	index += ins_size;
+	ins_size /= csum_size;
+	total_bytes += ins_size * fs_info->sectorsize;
+
+	btrfs_mark_buffer_dirty(path->nodes[0]);
+	if (total_bytes < sums->len) {
+		btrfs_release_path(path);
+		cond_resched();
+		goto again;
+	}
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
+				     const struct btrfs_path *path,
+				     struct btrfs_file_extent_item *fi,
+				     const bool new_inline,
+				     struct extent_map *em)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_root *root = inode->root;
+	struct extent_buffer *leaf = path->nodes[0];
+	const int slot = path->slots[0];
+	struct btrfs_key key;
+	u64 extent_start, extent_end;
+	u64 bytenr;
+	u8 type = btrfs_file_extent_type(leaf, fi);
+	int compress_type = btrfs_file_extent_compression(leaf, fi);
+
+	btrfs_item_key_to_cpu(leaf, &key, slot);
+	extent_start = key.offset;
+	extent_end = btrfs_file_extent_end(path);
+	em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
+	em->generation = btrfs_file_extent_generation(leaf, fi);
+	if (type == BTRFS_FILE_EXTENT_REG ||
+	    type == BTRFS_FILE_EXTENT_PREALLOC) {
+		em->start = extent_start;
+		em->len = extent_end - extent_start;
+		em->orig_start = extent_start -
+			btrfs_file_extent_offset(leaf, fi);
+		em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
+		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+		if (bytenr == 0) {
+			em->block_start = EXTENT_MAP_HOLE;
+			return;
+		}
+		if (compress_type != BTRFS_COMPRESS_NONE) {
+			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+			em->compress_type = compress_type;
+			em->block_start = bytenr;
+			em->block_len = em->orig_block_len;
+		} else {
+			bytenr += btrfs_file_extent_offset(leaf, fi);
+			em->block_start = bytenr;
+			em->block_len = em->len;
+			if (type == BTRFS_FILE_EXTENT_PREALLOC)
+				set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
+		}
+	} else if (type == BTRFS_FILE_EXTENT_INLINE) {
+		em->block_start = EXTENT_MAP_INLINE;
+		em->start = extent_start;
+		em->len = extent_end - extent_start;
+		/*
+		 * Initialize orig_start and block_len with the same values
+		 * as in inode.c:btrfs_get_extent().
+		 */
+		em->orig_start = EXTENT_MAP_HOLE;
+		em->block_len = (u64)-1;
+		if (!new_inline && compress_type != BTRFS_COMPRESS_NONE) {
+			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+			em->compress_type = compress_type;
+		}
+	} else {
+		btrfs_err(fs_info,
+			  "unknown file extent item type %d, inode %llu, offset %llu, "
+			  "root %llu", type, btrfs_ino(inode), extent_start,
+			  root->root_key.objectid);
+	}
+}
+
+/*
+ * Returns the end offset (non inclusive) of the file extent item the given path
+ * points to. If it points to an inline extent, the returned offset is rounded
+ * up to the sector size.
+ */
+u64 btrfs_file_extent_end(const struct btrfs_path *path)
+{
+	const struct extent_buffer *leaf = path->nodes[0];
+	const int slot = path->slots[0];
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_key key;
+	u64 end;
+
+	btrfs_item_key_to_cpu(leaf, &key, slot);
+	ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
+	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+
+	if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
+		end = btrfs_file_extent_ram_bytes(leaf, fi);
+		end = ALIGN(key.offset + end, leaf->fs_info->sectorsize);
+	} else {
+		end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
+	}
+
+	return end;
+}