[PATCH] md: teach raid5 the difference between 'check' and 'repair'.

With this, raid5 can be asked to check parity without repairing it.  It also
keeps a count of the number of incorrect parity blocks found (mismatches) and
reports them through sysfs.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 121fbaa9ed59..ce154553aca5 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1292,6 +1292,11 @@ static void handle_stripe(struct stripe_head *sh)
                             !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) {
                                 /* parity is correct (on disc, not in buffer any more) */
                                 set_bit(STRIPE_INSYNC, &sh->state);
+                        } else {
+                                conf->mddev->resync_mismatches += STRIPE_SECTORS;
+                                if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
+                                        /* don't try to repair!! */
+                                        set_bit(STRIPE_INSYNC, &sh->state);
                         }
                 }
                 if (!test_bit(STRIPE_INSYNC, &sh->state)) {