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Message-ID: <fd8a6edb-7775-4e15-9124-3be3c11adec0@oracle.com>
Date: Fri, 1 Nov 2024 16:23:57 +0000
From: John Garry <john.g.garry@...cle.com>
To: Johannes Thumshirn <jth@...nel.org>, Chris Mason <clm@...com>,
Josef Bacik <josef@...icpanda.com>, David Sterba <dsterba@...e.com>,
"open list:BTRFS FILE SYSTEM" <linux-btrfs@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Cc: linux-block@...r.kernel.org, Dan Carpenter <dan.carpenter@...aro.org>,
Johannes Thumshirn <johannes.thumshirn@....com>
Subject: Re: [PATCH v2] btrfs: handle bio_split() error
On 31/10/2024 14:44, Johannes Thumshirn wrote:
> From: Johannes Thumshirn <johannes.thumshirn@....com>
>
> Now that bio_split() can return errors, add error handling for it in
> btrfs_split_bio() and ultimately btrfs_submit_chunk().
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@....com>
> ---
>
> This is based on top of John Garry's series "bio_split() error handling
> rework" explicitly on the patch titled "block: Rework bio_split() return
> value", which are as of now (Tue Oct 29 10:02:16 2024) not yet merged into
> any tree.
>
> Changes to v1:
> - convert ERR_PTR to blk_status_t
> - correctly fail already split bbios
> ---
> fs/btrfs/bio.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
> index 1f216d07eff6..d2cfef5e4d4a 100644
> --- a/fs/btrfs/bio.c
> +++ b/fs/btrfs/bio.c
> @@ -81,6 +81,9 @@ static struct btrfs_bio *btrfs_split_bio(struct btrfs_fs_info *fs_info,
>
> bio = bio_split(&orig_bbio->bio, map_length >> SECTOR_SHIFT, GFP_NOFS,
> &btrfs_clone_bioset);
> + if (IS_ERR(bio))
> + return ERR_CAST(bio);
> +
> bbio = btrfs_bio(bio);
> btrfs_bio_init(bbio, fs_info, NULL, orig_bbio);
> bbio->inode = orig_bbio->inode;
> @@ -687,6 +690,10 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
>
> if (map_length < length) {
> bbio = btrfs_split_bio(fs_info, bbio, map_length);
> + if (IS_ERR(bbio)) {
> + ret = errno_to_blk_status(PTR_ERR(bbio));
btrfs_split_bio() does splitting, but error means "goto fail". However
other failure points "goto fail_split". I find that label naming odd.
Furthermore, at "fail", we call btrfs_bio_end_io() and that function
dereferences bbio (which is -EINVAL or something like that)
Thanks,
John
> + goto fail;
> + }
> bio = &bbio->bio;
> }
>
> @@ -698,7 +705,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
> bbio->saved_iter = bio->bi_iter;
> ret = btrfs_lookup_bio_sums(bbio);
> if (ret)
> - goto fail;
> + goto fail_split;
> }
>
> if (btrfs_op(bio) == BTRFS_MAP_WRITE) {
> @@ -732,13 +739,13 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
>
> ret = btrfs_bio_csum(bbio);
> if (ret)
> - goto fail;
> + goto fail_split;
> } else if (use_append ||
> (btrfs_is_zoned(fs_info) && inode &&
> inode->flags & BTRFS_INODE_NODATASUM)) {
> ret = btrfs_alloc_dummy_sum(bbio);
> if (ret)
> - goto fail;
> + goto fail_split;
> }
> }
>
> @@ -746,7 +753,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
> done:
> return map_length == length;
>
> -fail:
> +fail_split:
> btrfs_bio_counter_dec(fs_info);
> /*
> * We have split the original bbio, now we have to end both the current
> @@ -760,6 +767,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
>
> btrfs_bio_end_io(remaining, ret);
> }
> +fail:
> btrfs_bio_end_io(bbio, ret);
> /* Do not submit another chunk */
> return true;
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