Re: [PATCH] md/raid5: Fix bio retry on interrupted reshape

Dear Nigel,


Thank you for your patch.

Am 29.04.26 um 13:10 schrieb Nigel Croxon:
> When a bio encounters LOC_INSIDE_RESHAPE during a reshape that is
> interrupted (stopped or unable to progress), the code sets
> bi->bi_status = BLK_STS_RESOURCE to signal the block layer for retry.
> However, bio_endio() is never called, so the block layer never
> receives the completion notification and the retry never happens.
> 
> This causes I/O to hang when a filesystem is layered over RAID5 and
> reshape gets stuck.
> 
> Fix this by calling bio_endio(bi) before md_free_cloned_bio(bi) so
> the block layer is properly notified of the BLK_STS_RESOURCE status
> and can retry the request.
> 
> Tested stripes and stripe size conversions under load comparing
> files multiple times during each conversion (i.e. MD reshape) on
> ext4 after dropping caches degrading the RaidLV each time and

I thought RaidLV misspelled Raid V (Raid 5), so should you resend, maybe 
write it as RAID LV.

> no data corruption.
> 
> Fixes: https://lwn.net/Articles/757123/

Which paragraph/comment exactly?

> Signed-off-by: Nigel Croxon <[email protected]>
> ---
>   drivers/md/raid5.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 6e79829c5acb..9a3475429ef4 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -6217,6 +6217,7 @@ static bool raid5_make_request(struct mddev 
> *mddev, struct bio * bi)
> 
>       mempool_free(ctx, conf->ctx_pool);
>       if (res == STRIPE_WAIT_RESHAPE) {
> +         bio_endio(bi);
>           md_free_cloned_bio(bi);
>           return false;
>       }

Reviewed-by: Paul Menzel <[email protected]>


Kind regards,

Paul