On Wed, Mar 29, 2017 at 09:33:19AM +0800, Qu Wenruo wrote:
[...]
>
> Reported-by: Goffredo Baroncelli <kreij...@libero.it>
> Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
> ---
> fs/btrfs/scrub.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index ab33b9a8aac2..f92d2512f4f3 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -1129,6 +1129,17 @@ static int scrub_handle_errored_block(struct
> scrub_block *sblock_to_check)
> have_csum = sblock_to_check->pagev[0]->have_csum;
> dev = sblock_to_check->pagev[0]->dev;
>
> + /*
> + * For RAID5/6 race can happen for different dev scrub thread.
> + * For data corruption, Parity and Data thread will both try
> + * to recovery the data.
> + * Race can lead to double added csum error, or even unrecoverable
> + * error.
> + */
> + ret = lock_full_stripe(fs_info, logical);
> + if (ret < 0)
> + return ret;
> +
Firstly, sctx->stat needs to be set with errors before returning errors.
Secondly, I think the critical section starts right before re-checking the
failed mirror, doesn't it? If so, we could get the benefit from
sblock_bad->page since the page->recover can tell if this is a raid56 profile so
that we may save a searching for block group.
> if (sctx->is_dev_replace && !is_metadata && !have_csum) {
> sblocks_for_recheck = NULL;
> goto nodatasum_case;
> @@ -1463,6 +1474,9 @@ static int scrub_handle_errored_block(struct
> scrub_block *sblock_to_check)
> kfree(sblocks_for_recheck);
> }
>
> + ret = unlock_full_stripe(fs_info, logical);
> + if (ret < 0)
> + return ret;
Seems that the callers of scrub_handle_errored_block doesn't care about @ret.
And could you please put a 'locked' flag after taking the lock succesfully?
Otherwise every raid profile has to check block group for raid flag.
Thanks,
-liubo
> return 0;
> }
>
> --
> 2.12.1
>
>
>
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