fuse: destroy bdi on umount

If a fuse filesystem is unmounted but the device file descriptor
remains open and a new mount reuses the old device number, then the
mount fails with EEXIST and the following warning is printed in the
kernel log:

  WARNING: at fs/sysfs/dir.c:462 sysfs_add_one+0x35/0x3d()
  sysfs: duplicate filename '0:15' can not be created

The cause is that the bdi belonging to the fuse filesystem was
destoryed only after the device file was released.  Fix this by
calling bdi_destroy() from fuse_put_super() instead.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index e0c7ada08a1f..c4a3d9bbdaa8 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -281,7 +281,8 @@ __releases(&fc->lock)
                         fc->blocked = 0;
                         wake_up_all(&fc->blocked_waitq);
                 }
-                if (fc->num_background == FUSE_CONGESTION_THRESHOLD) {
+                if (fc->num_background == FUSE_CONGESTION_THRESHOLD &&
+                    fc->connected) {
                         clear_bdi_congested(&fc->bdi, READ);
                         clear_bdi_congested(&fc->bdi, WRITE);
                 }