Merge branch 'for-linus' of git://git.kernel.dk/linux-block

[linux-2.6-block.git] / drivers / block / loop.c

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e9d594fd12cbee408251c4ead03d1b71183ff7ae..54046e51160aef28e3ee733797fa453a0403a02a 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -976,8 +976,21 @@ static int loop_clr_fd(struct loop_device *lo)
        if (lo->lo_state != Lo_bound)
                return -ENXIO;
 
-       if (lo->lo_refcnt > 1)  /* we needed one fd for the ioctl */
-               return -EBUSY;
+       /*
+        * If we've explicitly asked to tear down the loop device,
+        * and it has an elevated reference count, set it for auto-teardown when
+        * the last reference goes away. This stops $!~#$@ udev from
+        * preventing teardown because it decided that it needs to run blkid on
+        * the loopback device whenever they appear. xfstests is notorious for
+        * failing tests because blkid via udev races with a losetup
+        * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
+        * command to fail with EBUSY.
+        */
+       if (lo->lo_refcnt > 1) {
+               lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
+               mutex_unlock(&lo->lo_ctl_mutex);
+               return 0;
+       }
 
        if (filp == NULL)
                return -EINVAL;