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md: close a livelock window in handle_parity_checks5 

If a failure is detected after a parity check operation has been initiated,
but before it completes handle_parity_checks5 will never quiesce operations on
the stripe.

Explicitly handle this case by "canceling" the parity check, i.e.  clear the
STRIPE_OP_CHECK flags and queue the stripe on the handle list again to refresh
any non-uptodate blocks.

Kernel versions >= 2.6.23 are susceptible.

Cc: <stable@kernel.org>
Cc: NeilBrown <neilb@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2008-04-10 21:29:27 -07:00 коммит произвёл Linus Torvalds
Родитель 231bc2a222
Коммит bd2ab67030
1 изменённых файлов: 31 добавлений и 24 удалений
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55
drivers/md/raid5.c
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@ -2348,25 +2348,15 @@ static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
struct stripe_head_state *s, int disks)
{
set_bit(STRIPE_HANDLE, &sh->state);
/* Take one of the following actions:
* 1/ start a check parity operation if (uptodate == disks)
* 2/ finish a check parity operation and act on the result
* 3/ skip to the writeback section if we previously
* initiated a recovery operation
*/
if (s->failed == 0 &&
!test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
BUG_ON(s->uptodate != disks);
clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
sh->ops.count++;
s->uptodate--;
} else if (
test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) {
clear_bit(STRIPE_OP_CHECK, &sh->ops.ack);
clear_bit(STRIPE_OP_CHECK, &sh->ops.pending);
int canceled_check = 0;
set_bit(STRIPE_HANDLE, &sh->state);
/* complete a check operation */
if (test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) {
clear_bit(STRIPE_OP_CHECK, &sh->ops.ack);
clear_bit(STRIPE_OP_CHECK, &sh->ops.pending);
if (s->failed == 0) {
if (sh->ops.zero_sum_result == 0)
/* parity is correct (on disc,
* not in buffer any more)
@ -2391,7 +2381,8 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
s->uptodate++;
}
}
}
} else
canceled_check = 1; /* STRIPE_INSYNC is not set */
}
/* check if we can clear a parity disk reconstruct */
@ -2404,12 +2395,28 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
}
/* Wait for check parity and compute block operations to complete
* before write-back
/* start a new check operation if there are no failures, the stripe is
* not insync, and a repair is not in flight
*/
if (!test_bit(STRIPE_INSYNC, &sh->state) &&
!test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
if (s->failed == 0 &&
!test_bit(STRIPE_INSYNC, &sh->state) &&
!test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
BUG_ON(s->uptodate != disks);
clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
sh->ops.count++;
s->uptodate--;
}
}
/* Wait for check parity and compute block operations to complete
* before write-back. If a failure occurred while the check operation
* was in flight we need to cycle this stripe through handle_stripe
* since the parity block may not be uptodate
*/
if (!canceled_check && !test_bit(STRIPE_INSYNC, &sh->state) &&
!test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
struct r5dev *dev;
/* either failed parity check, or recovery is happening */
if (s->failed == 0)