Re: [PATCH] btrfs: Record error in btree_csum_one_bio()

From: Nikolay Borisov <nborisov@suse.com>
To: Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs: Record error in btree_csum_one_bio()
Date: Sat, 6 Apr 2019 09:15:57 +0300	[thread overview]
Message-ID: <e8b16a1b-5363-b025-3820-b5b97d338097@suse.com> (raw)
In-Reply-To: <20190406031346.22365-1-wqu@suse.com>

On 6.04.19 г. 6:13 ч., Qu Wenruo wrote:
> Since commit 6dc4f100c175 ("block: allow bio_for_each_segment_all() to
> iterate over multi-page bvec"), break will only break the inner loop of
> bio_for_each_segment_all(), unable to break the outer loop.

Breaking of outer loop should be implemented with a goto rather than
introducing a new variable.

> 
> So here we add a new variable @err to record the first error we hit, and
> return the error, so that write time checker can work as designed.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>  fs/btrfs/disk-io.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 6fe9197f6ee4..9e4d129bb649 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -832,18 +832,18 @@ static blk_status_t btree_csum_one_bio(struct bio *bio)
>  {
>  	struct bio_vec *bvec;
>  	struct btrfs_root *root;
> -	int i, ret = 0;
> +	int i, ret = 0, err = 0;
>  	struct bvec_iter_all iter_all;
>  
>  	ASSERT(!bio_flagged(bio, BIO_CLONED));
>  	bio_for_each_segment_all(bvec, bio, i, iter_all) {
>  		root = BTRFS_I(bvec->bv_page->mapping->host)->root;
>  		ret = csum_dirty_buffer(root->fs_info, bvec->bv_page);
> -		if (ret)
> -			break;
> +		if (ret && !err)
> +			err = ret;
>  	}
>  
> -	return errno_to_blk_status(ret);
> +	return errno_to_blk_status(err);
>  }
>  
>  static blk_status_t btree_submit_bio_start(void *private_data, struct bio *bio,
> 