[PATCH] dm: use gcd() to fix chunk_sectors limit stacking

From: Jeffle Xu <jefflexu@linux.alibaba.com>
To: snitzer@redhat.com
Cc: dm-devel@redhat.com, joseph.qi@linux.alibaba.com,
	linux-block@vger.kernel.org
Subject: [PATCH] dm: use gcd() to fix chunk_sectors limit stacking
Date: Wed,  2 Dec 2020 11:38:54 +0800	[thread overview]
Message-ID: <20201202033855.60882-1-jefflexu@linux.alibaba.com> (raw)
In-Reply-To: <20201201160709.31748-1-snitzer@redhat.com>

As it said in commit 7e7986f9d3ba ("block: use gcd() to fix
chunk_sectors limit stacking"), chunk_sectors should reflect the most
limited of all devices in the IO stack.

The previous commit only fixes block/blk-settings.c:blk_stack_limits(),
while leaving dm.c:dm_calculate_queue_limits() unfixed.

Fixes: 882ec4e609c1 ("dm table: stack 'chunk_sectors' limit to account for target-specific splitting")
cc: stable@vger.kernel.org
Reported-by: John Dorminy <jdorminy@redhat.com>
Reported-by: Bruce Johnston <bjohnsto@redhat.com>
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 drivers/md/dm-table.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index ce543b761be7..dcc0a27355d7 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -22,6 +22,7 @@
 #include <linux/blk-mq.h>
 #include <linux/mount.h>
 #include <linux/dax.h>
+#include <linux/gcd.h>
 
 #define DM_MSG_PREFIX "table"
 
@@ -1457,7 +1458,7 @@ int dm_calculate_queue_limits(struct dm_table *table,
 
 		/* Stack chunk_sectors if target-specific splitting is required */
 		if (ti->max_io_len)
-			ti_limits.chunk_sectors = lcm_not_zero(ti->max_io_len,
+			ti_limits.chunk_sectors = gcd(ti->max_io_len,
 							       ti_limits.chunk_sectors);
 		/* Set I/O hints portion of queue limits */
 		if (ti->type->io_hints)
-- 
2.27.0

