1 files changed, 23 insertions, 2 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index fe41a76769fa..fe09ef9c21f3 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1058,6 +1058,27 @@ retry:
         return 0;
 }
 
+static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
+{
+        struct gendisk *disk = get_gendisk(bdev->bd_dev, partno);
+
+        if (!disk)
+                return NULL;
+        /*
+         * Now that we hold gendisk reference we make sure bdev we looked up is
+         * not stale. If it is, it means device got removed and created before
+         * we looked up gendisk and we fail open in such case. Associating
+         * unhashed bdev with newly created gendisk could lead to two bdevs
+         * (and thus two independent caches) being associated with one device
+         * which is bad.
+         */
+        if (inode_unhashed(bdev->bd_inode)) {
+                put_disk_and_module(disk);
+                return NULL;
+        }
+        return disk;
+}
+
 /**
  * bd_start_claiming - start claiming a block device
  * @bdev: block device of interest
@@ -1094,7 +1115,7 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
          * @bdev might not have been initialized properly yet, look up
          * and grab the outer block device the hard way.
          */
-        disk = get_gendisk(bdev->bd_dev, &partno);
+        disk = bdev_get_gendisk(bdev, &partno);
         if (!disk)
                 return ERR_PTR(-ENXIO);
 
@@ -1429,7 +1450,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
  restart:
 
         ret = -ENXIO;
-        disk = get_gendisk(bdev->bd_dev, &partno);
+        disk = bdev_get_gendisk(bdev, &partno);
         if (!disk)
                 goto out;