Re: [PATCH 1/4] md/raid5: Reduce one write-operation when handle badsector

[NeilBrown <neilb@suse.de>]

[-- Attachment #1: Type: text/plain, Size: 1805 bytes --]

On Mon, 4 Mar 2013 09:52:57 +0800 majianpeng <majianpeng@gmail.com> wrote:

> >On Thu, 28 Feb 2013 15:51:01 +0800 majianpeng <majianpeng@gmail.com> wrote:
> >
> >> For badsector,it took two steps:rewrite and reread.So for
> >> write-operation,it make no sense to rewrite after write-operation.
> >
> >Please please please please please try to explain yourself better.
> >
> Sorry for that. 
> >This patch doesn't make any sense.  The write succeeded.  We set the MadeGood
> >flag so that later code will remove the block from the bad-block list.
> >There will be no re-read or re-write.
> >
> For a striep which contain badsector is doing write-operation.
> In analyse_stripe, it check badsector and set R5_ReadError.
>  write--->MadeGood->clear badblock log. But it can't clear R5_ReadError flag.
> So it will exec those code in func handle_stripe:

After you wrote that, did you read it again to see if it makes any sense?  It
does but only just.

I'd rather have a good explanation in the code so it is clear what is going
on.

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3e0ec16..277d9c2 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1911,8 +1911,15 @@ static void raid5_end_write_request(struct bio *bi, int error)
 					&rdev->mddev->recovery);
 		} else if (is_badblock(rdev, sh->sector,
 				       STRIPE_SECTORS,
-				       &first_bad, &bad_sectors))
+				       &first_bad, &bad_sectors)) {
 			set_bit(R5_MadeGood, &sh->dev[i].flags);
+			if (test_bit(R5_ReadError, &sh->dev[i].flags))
+				/* That was a successful write so make
+				 * sure it looks like we already did
+				 * a re-write.
+				 */
+				set_bit(R5_ReWrite, &sh->dev[i].flags);
+		}
 	}
 	rdev_dec_pending(rdev, conf->mddev);
 
Thanks,
NeilBrown

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 828 bytes --]