Re: [PATCH 05/15] btrfs: clarify btrfs_lookup_bio_sums documentation

From: Josef Bacik <josef@toxicpanda.com>
To: Omar Sandoval <osandov@osandov.com>, linux-btrfs@vger.kernel.org
Cc: kernel-team@fb.com, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 05/15] btrfs: clarify btrfs_lookup_bio_sums documentation
Date: Wed, 11 Mar 2020 13:56:44 -0400	[thread overview]
Message-ID: <a7522f01-8aad-bdcc-4576-4c73d7719bc9@toxicpanda.com> (raw)
In-Reply-To: <2ee5f090b52dc23569bf94a5a2609dfc49ac4a4b.1583789410.git.osandov@fb.com>

On 3/9/20 5:32 PM, 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.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>   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?

Josef