On Wed, Mar 11, 2020 at 01:56:44PM -0400, Josef Bacik wrote:
> On 3/9/20 5:32 PM, Omar Sandoval wrote:
> > 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);
> > +
>
> Looks like you have some extra changes in here?
I mentioned it in the commit message: "Move the declaration in the code
to make that clear". It looks weird to document that the bio only needs
to be a btrfs_io_bio if dst == NULL and then always get the btrfs_bio,
even if we don't use it.
