[dm-devel] [PATCH 11/17] btrfs: make dec_and_test_compressed_bio() to be split bio compatible

[Josef Bacik]

On Wed, Dec 01, 2021 at 01:17:50PM +0800, Qu Wenruo wrote:
> For compression read write endio functions, they all rely on
> dec_and_test_compressed_bio() to determine if they are the last bio.
> 
> So here we only need to convert the bio_for_each_segment_all() call into
> __bio_for_each_segment() so that compression read/write endio functions
> will handle both split and unsplit bios well.
> 
> Signed-off-by: Qu Wenruo <wqu at suse.com>
> ---
>  fs/btrfs/compression.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index 8668c5190805..8b4b84b59b0c 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -205,18 +205,14 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
>  static bool dec_and_test_compressed_bio(struct compressed_bio *cb, struct bio *bio)
>  {
>  	struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
> +	struct bio_vec bvec;
> +	struct bvec_iter iter;
>  	unsigned int bi_size = 0;
>  	bool last_io = false;
> -	struct bio_vec *bvec;
> -	struct bvec_iter_all iter_all;
>  
> -	/*
> -	 * At endio time, bi_iter.bi_size doesn't represent the real bio size.
> -	 * Thus here we have to iterate through all segments to grab correct
> -	 * bio size.
> -	 */
> -	bio_for_each_segment_all(bvec, bio, iter_all)
> -		bi_size += bvec->bv_len;
> +	ASSERT(btrfs_bio(bio)->iter.bi_size);

We're tripping this assert with generic/476 with -o compress, so I assume
there's some error condition that isn't being handled properly.  Thanks,

Josef