[dm-devel] [PATCH] dm mirror: fix regression caused by

[dm-devel] [PATCH] dm mirror: fix regression caused by

[Mikulas Patocka]

The commit 85e123c27d5c introduced a regression on 64-bit architectures in
the lvm testsuite tests lvcreate-mirror, mirror-names and
vgsplit-operation.

If the device is shrunk, we need to clear log bits beyond the end of the 
device. The code clears bits up to a 32-bit boundary and then calculates 
lc->sync_count by summing set bits up to a 64-bit boundary (that commit 
changed that; previously, this boundary was 32-bit too). So, it was using 
some non-zeroed bits in the calculation and this caused misbehavior.

We fix this bug by clearing bits up to BITS_PER_LONG boundary.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 85e123c27d5c ("dm mirror log: round up region bitmap size to BITS_PER_LONG")
Cc: stable@vger.kernel.org

---
 drivers/md/dm-log.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6/drivers/md/dm-log.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-log.c	2022-06-23 20:32:05.000000000 +0200
+++ linux-2.6/drivers/md/dm-log.c	2022-06-23 20:33:42.000000000 +0200
@@ -615,7 +615,7 @@ static int disk_resume(struct dm_dirty_l
 			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++)
+	for (i = lc->region_count; i % BITS_PER_LONG; i++)
 		log_clear_bit(lc, lc->clean_bits, i);
 
 	/* copy clean across to sync */
--
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