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-rw-r--r--drivers/md/dm.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f1db689667ea..59806e67a175 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -925,6 +925,16 @@ static int dm_merge_bvec(struct request_queue *q,
*/
if (max_size && ti->type->merge)
max_size = ti->type->merge(ti, bvm, biovec, max_size);
+ /*
+ * If the target doesn't support merge method and some of the devices
+ * provided their merge_bvec method (we know this by looking at
+ * queue_max_hw_sectors), then we can't allow bios with multiple vector
+ * entries. So always set max_size to 0, and the code below allows
+ * just one page.
+ */
+ else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
+
+ max_size = 0;
out_table:
dm_table_put(map);