commit bd2ab67030e9116f1e4aae1289220255412b37fd "md: close a livelock
window in handle_parity_checks5" introduced a bug in handling 'repair'
operations. After a repair operation completes we clear the state bits
tracking this operation. However, they are cleared too early and this
results in the code deciding to re-run the parity check operation. Since
we have done the repair in memory the second check does not find a mismatch
and thus does not do a writeback.
Test results:
$ echo repair > /sys/block/md0/md/sync_action
$ cat /sys/block/md0/md/mismatch_cnt
51072
$ echo repair > /sys/block/md0/md/sync_action
$ cat /sys/block/md0/md/mismatch_cnt
0
Cc: <stable@xxxxxxxxxx>
Reported-by: George Spelvin <linux@xxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/md/raid5.c | 21 +++++++++++----------
1 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 087eee0..da3390d 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2400,16 +2400,6 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
canceled_check = 1; /* STRIPE_INSYNC is not set */
}
- /* check if we can clear a parity disk reconstruct */
- if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
- test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
-
- clear_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending);
- clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
- clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
- 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
*/
@@ -2424,6 +2414,17 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
}
}
+ /* check if we can clear a parity disk reconstruct */
+ if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
+ test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
+
+ clear_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending);
+ clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
+ clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
+ clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
+ }
+
+
/* 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
--
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