md: fix raid5 'repair' operations

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

(also fix incorrect indentation)

Cc: <stable@kernel.org>
Tested-by: George Spelvin <linux@horizon.com>
Acked-by: 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>

1 files changed, 13 insertions, 12 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 087eee0cb809..ee0ea9183080 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2369,8 +2369,8 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
 
         /* 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);
+                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,
@@ -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