NFS: Fix a umount race
Ensure that we unregister the bdi before kill_anon_super() calls
ida_remove() on our device name.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index ce907ef..f1afee4 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -243,6 +243,7 @@
static int nfs_get_sb(struct file_system_type *, int, const char *, void *, struct vfsmount *);
static int nfs_xdev_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
+static void nfs_put_super(struct super_block *);
static void nfs_kill_super(struct super_block *);
static int nfs_remount(struct super_block *sb, int *flags, char *raw_data);
@@ -266,6 +267,7 @@
.alloc_inode = nfs_alloc_inode,
.destroy_inode = nfs_destroy_inode,
.write_inode = nfs_write_inode,
+ .put_super = nfs_put_super,
.statfs = nfs_statfs,
.clear_inode = nfs_clear_inode,
.umount_begin = nfs_umount_begin,
@@ -335,6 +337,7 @@
.alloc_inode = nfs_alloc_inode,
.destroy_inode = nfs_destroy_inode,
.write_inode = nfs_write_inode,
+ .put_super = nfs_put_super,
.statfs = nfs_statfs,
.clear_inode = nfs4_clear_inode,
.umount_begin = nfs_umount_begin,
@@ -2258,6 +2261,17 @@
}
/*
+ * Ensure that we unregister the bdi before kill_anon_super
+ * releases the device name
+ */
+static void nfs_put_super(struct super_block *s)
+{
+ struct nfs_server *server = NFS_SB(s);
+
+ bdi_unregister(&server->backing_dev_info);
+}
+
+/*
* Destroy an NFS2/3 superblock
*/
static void nfs_kill_super(struct super_block *s)
@@ -2265,7 +2279,6 @@
struct nfs_server *server = NFS_SB(s);
kill_anon_super(s);
- bdi_unregister(&server->backing_dev_info);
nfs_fscache_release_super_cookie(s);
nfs_free_server(server);
}