Re: [PATCH 7/8] btrfs: do not try to repair bio that has no mirror set

[Boris Burkov <boris@bur.io>]

On Thu, Feb 10, 2022 at 05:44:25PM -0500, Josef Bacik wrote:
> If we fail to submit a bio for whatever reason, we may not have setup a
> mirror_num for that bio.  This means we shouldn't try to do the repair
> workflow, if we do we'll hit an BUG_ON(!failrec->this_mirror) in
> clean_io_failure.  Instead simply skip the repair workflow if we have no
> mirror set, and add an assert to btrfs_check_repairable() to make it
> easier to catch what is happening in the future.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Boris Burkov <boris@bur.io>
> ---
>  fs/btrfs/extent_io.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index bda7fa8cf540..29ffb2814e5c 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2610,6 +2610,7 @@ static bool btrfs_check_repairable(struct inode *inode,
>  	 * a good copy of the failed sector and if we succeed, we have setup
>  	 * everything for repair_io_failure to do the rest for us.
>  	 */
> +	ASSERT(failed_mirror);
>  	failrec->failed_mirror = failed_mirror;
>  	failrec->this_mirror++;
>  	if (failrec->this_mirror == failed_mirror)
> @@ -3067,6 +3068,14 @@ static void end_bio_extent_readpage(struct bio *bio)
>  			goto readpage_ok;
>  
>  		if (is_data_inode(inode)) {
> +			/*
> +			 * If we failed to submit the IO at all we'll have a
> +			 * mirror_num == 0, in which case we need to just mark
> +			 * the page with an error and unlock it and carry on.
> +			 */
> +			if (mirror == 0)
> +				goto readpage_ok;
> +
>  			/*
>  			 * btrfs_submit_read_repair() will handle all the good
>  			 * and bad sectors, we just continue to the next bvec.
> -- 
> 2.26.3
>