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authorDan Williams <dan.j.williams@intel.com>2008-04-10 21:29:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-11 08:06:44 -0700
commitbd2ab67030e9116f1e4aae1289220255412b37fd (patch)
treeda52cf8952a660f17ce45c8c510ded9a3487180a
parent231bc2a222411f43bfb0fbb6d64c0f34c7b1039f (diff)
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>
-rw-r--r--drivers/md/raid5.c51
1 files changed, 29 insertions, 22 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index c574cf5efb5c..b162b839a662 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -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)
{
+ int canceled_check = 0;
+
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);
+ /* 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);
}
+ /* start a new check operation if there are no failures, the stripe is
+ * not insync, and a repair is not in flight
+ */
+ 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
+ * 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 (!test_bit(STRIPE_INSYNC, &sh->state) &&
- !test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
- !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
+ 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)