1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 215e112d153e..451c3bb176d2 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -362,6 +362,7 @@ static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
 static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
                                   sector_t start, sector_t len, void *data)
 {
+        struct request_queue *q;
         struct queue_limits *limits = data;
         struct block_device *bdev = dev->bdev;
         sector_t dev_size =
@@ -370,6 +371,22 @@ static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
                 limits->logical_block_size >> SECTOR_SHIFT;
         char b[BDEVNAME_SIZE];
 
+        /*
+         * Some devices exist without request functions,
+         * such as loop devices not yet bound to backing files.
+         * Forbid the use of such devices.
+         */
+        q = bdev_get_queue(bdev);
+        if (!q || !q->make_request_fn) {
+                DMWARN("%s: %s is not yet initialised: "
+                       "start=%llu, len=%llu, dev_size=%llu",
+                       dm_device_name(ti->table->md), bdevname(bdev, b),
+                       (unsigned long long)start,
+                       (unsigned long long)len,
+                       (unsigned long long)dev_size);
+                return 1;
+        }
+
         if (!dev_size)
                 return 0;