diff mbox series

[v2,06/15] btrfs: clarify btrfs_lookup_bio_sums documentation

Message ID 51f9f9b917ded1057f1d24f7bbf7546492f3ea98.1587072977.git.osandov@fb.com (mailing list archive)
State New, archived
Headers show
Series btrfs: read repair/direct I/O improvements | expand

Commit Message

Omar Sandoval April 16, 2020, 9:46 p.m. UTC 
From: Omar Sandoval <osandov@fb.com>

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.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 fs/btrfs/file-item.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Comments

Johannes Thumshirn April 17, 2020, 6:01 p.m. UTC | #1 
On 16/04/2020 23:47, Omar Sandoval wrote:
> 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.

And also reduce the scope of 'btrfs_bio'?

Otherwise,
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Nikolay Borisov April 21, 2020, 11:17 a.m. UTC | #2 
On 17.04.20 г. 0:46 ч., Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> 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.
> 
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Omar Sandoval <osandov@fb.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
diff mbox series

Patch

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index b618ad5339ba..22cbb4da6d42 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 / fs_info->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);