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Commit c8894419 authored by Dan Williams's avatar Dan Williams Committed by Linus Torvalds
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md: fix raid5 'repair' operations 



commit bd2ab670 "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: default avatarGeorge Spelvin <linux@horizon.com>
Acked-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3f275ea3

drivers/md/raid5.c

+13 −12
Original line number Diff line number Diff line
@@ -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