From: Omar Sandoval <osandov@xxxxxx>
Fix a couple of issues in the btrfs_lookup_bio_sums documentation:
* The bio doesn't need to be a btrfs_io_bio if dst was provided. Move
the declaration in the code to make that clear, too.
* dst must be large enough to hold nblocks * csum_size, not just
csum_size.
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
---
fs/btrfs/file-item.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 6c849e8fd5a1..fa9f4a92f74d 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -242,11 +242,13 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
/**
* btrfs_lookup_bio_sums - Look up checksums for a bio.
* @inode: inode that the bio is for.
- * @bio: bio embedded in btrfs_io_bio.
+ * @bio: bio to look up.
* @offset: Unless (u64)-1, look up checksums for this offset in the file.
* If (u64)-1, use the page offsets from the bio instead.
- * @dst: Buffer of size btrfs_super_csum_size() used to return checksum. If
- * NULL, the checksum is returned in btrfs_io_bio(bio)->csum instead.
+ * @dst: Buffer of size nblocks * btrfs_super_csum_size() used to return
+ * checksum (nblocks = bio->bi_iter.bi_size / sectorsize). If NULL, the
+ * checksum buffer is allocated and returned in btrfs_io_bio(bio)->csum
+ * instead.
*
* Return: BLK_STS_RESOURCE if allocating memory fails, BLK_STS_OK otherwise.
*/
@@ -256,7 +258,6 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct bio_vec bvec;
struct bvec_iter iter;
- struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
struct btrfs_csum_item *item = NULL;
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct btrfs_path *path;
@@ -277,6 +278,8 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
if (!dst) {
+ struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
+
if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
btrfs_bio->csum = kmalloc_array(nblocks, csum_size,
GFP_NOFS);
--
2.25.1
