- int r = __table_get_device(ti->table, ti, path,
- start, len, mode, result);
- if (!r) {
- request_queue_t *q = bdev_get_queue((*result)->bdev);
- struct io_restrictions *rs = &ti->limits;
-
- /*
- * Combine the device limits low.
- *
- * FIXME: if we move an io_restriction struct
- * into q this would just be a call to
- * combine_restrictions_low()
- */
+ struct request_queue *q = bdev_get_queue(bdev);
+ struct io_restrictions *rs = &ti->limits;
+ char b[BDEVNAME_SIZE];
+
+ if (unlikely(!q)) {
+ DMWARN("%s: Cannot set limits for nonexistent device %s",
+ dm_device_name(ti->table->md), bdevname(bdev, b));
+ return;
+ }
+
+ /*
+ * Combine the device limits low.
+ *
+ * FIXME: if we move an io_restriction struct
+ * into q this would just be a call to
+ * combine_restrictions_low()
+ */
+ rs->max_sectors =
+ min_not_zero(rs->max_sectors, q->max_sectors);
+
+ /*
+ * Check if merge fn is supported.
+ * If not we'll force DM to use PAGE_SIZE or
+ * smaller I/O, just to be safe.
+ */
+
+ if (q->merge_bvec_fn && !ti->type->merge)