[PATCH] fuse: fix bug in control filesystem mount

The BUG in fuse_ctl_add_dentry() could be triggered if the control
filesystem was unmounted and mounted again while one or more fuse
filesystems were present.

The fix is to reset the dentry counter in fuse_ctl_kill_sb().

Bug reported by Florent Mertens.
Signed-off-by: NMiklos Szeredi <miklos@szeredi.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/fuse/control.c

@@ -193,8 +193,12 @@ static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
 
 static void fuse_ctl_kill_sb(struct super_block *sb)
 {
+	struct fuse_conn *fc;
+
 	mutex_lock(&fuse_mutex);
 	fuse_control_sb = NULL;
+	list_for_each_entry(fc, &fuse_conn_list, entry)
+		fc->ctl_ndents = 0;
 	mutex_unlock(&fuse_mutex);
 
 	kill_litter_super(sb);