[PATCH] dm: lock limits when reading them

[Mikulas Patocka]

Lock queue limits when reading them, so that we don't read halfway
modified values.

Signed-off-by: Mikulas Patocka <mpato...@redhat.com>
Cc: sta...@vger.kernel.org

---
 drivers/md/dm-table.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/md/dm-table.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-table.c        2025-04-14 16:02:04.000000000 
+0200
+++ linux-2.6/drivers/md/dm-table.c     2025-04-14 16:02:04.000000000 +0200
@@ -431,6 +431,7 @@ static int dm_set_device_limits(struct d
                return 0;
        }
 
+       mutex_lock(&q->limits_lock);
        if (blk_stack_limits(limits, &q->limits,
                        get_start_sect(bdev) + start) < 0)
                DMWARN("%s: adding target device %pg caused an alignment 
inconsistency: "
@@ -448,6 +449,7 @@ static int dm_set_device_limits(struct d
         */
        if (!dm_target_has_integrity(ti->type))
                queue_limits_stack_integrity_bdev(limits, bdev);
+       mutex_unlock(&q->limits_lock);
        return 0;
 }
 
@@ -1722,8 +1724,12 @@ static int device_not_write_zeroes_capab
                                           sector_t start, sector_t len, void 
*data)
 {
        struct request_queue *q = bdev_get_queue(dev->bdev);
+       int b;
 
-       return !q->limits.max_write_zeroes_sectors;
+       mutex_lock(&q->limits_lock);
+       b = !q->limits.max_write_zeroes_sectors;
+       mutex_unlock(&q->limits_lock);
+       return b;
 }
 
 static bool dm_table_supports_write_zeroes(struct dm_table *t)