[PATCH] dm mirror log: sync_count fix

When a mirror is reduced in size, clear the part of the bitmap that is no
longer used.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 33d80721667..ba98bf57c7c 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -447,7 +447,7 @@ static int disk_resume(struct dirty_log *log)
         if (r)
                 return r;
 
-        /* set or clear any new bits */
+        /* set or clear any new bits -- device has grown */
         if (lc->sync == NOSYNC)
                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
                         /* FIXME: amazingly inefficient */
@@ -457,6 +457,10 @@ static int disk_resume(struct dirty_log *log)
                         /* FIXME: amazingly inefficient */
                         log_clear_bit(lc, lc->clean_bits, i);
 
+        /* clear any old bits -- device has shrunk */
+        for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
+                log_clear_bit(lc, lc->clean_bits, i);
+
         /* copy clean across to sync */
         memcpy(lc->sync_bits, lc->clean_bits, size);
         lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);