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md/raid5: Avoid BUG caused by multiple failures.

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While preparing to write a stripe we keep the parity block or blocks
locked (R5_LOCKED) - towards the end of schedule_reconstruction.

If the array is discovered to have failed before this write completes
we can leave those blocks LOCKED, and init_stripe will notice that a
free stripe still has a locked block and will complain.

So clear the R5_LOCKED flag in handle_failed_stripe, and demote the
'BUG' to a 'WARN_ON'.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown
2011-07-27 11:00:36 +10:00
parent cbea21703b
commit 8cfa7b0f67
1 changed files with 5 additions and 1 deletions
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6
drivers/md/raid5.c
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@@ -340,7 +340,7 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
(unsigned long long)sh->sector, i, dev->toread, (unsigned long long)sh->sector, i, dev->toread,
dev->read, dev->towrite, dev->written, dev->read, dev->towrite, dev->written,
test_bit(R5_LOCKED, &dev->flags)); test_bit(R5_LOCKED, &dev->flags));
BUG(); WARN_ON(1);
} }
dev->flags = 0; dev->flags = 0;
raid5_build_block(sh, i, previous); raid5_build_block(sh, i, previous);
@@ -2301,6 +2301,10 @@ handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
if (bitmap_end) if (bitmap_end)
bitmap_endwrite(conf->mddev->bitmap, sh->sector, bitmap_endwrite(conf->mddev->bitmap, sh->sector,
STRIPE_SECTORS, 0, 0); STRIPE_SECTORS, 0, 0);
/* If we were in the middle of a write the parity block might
* still be locked - so just clear all R5_LOCKED flags
*/
clear_bit(R5_LOCKED, &sh->dev[i].flags);
} }
if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state)) if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))