[PATCH] md: fix raid5 'repair' operations

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From: Dan Williams
Date: Friday, May 2, 2008 - 2:27 pm

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>
---

 drivers/md/raid5.c |   25 +++++++++++++------------
 1 files changed, 13 insertions(+), 12 deletions(-)


diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 087eee0..ee0ea91 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, &am