[PATCH] ReiserFS: Make sure all dentries refs are released before calling kill_block_super()

Make sure all dentries refs are released before calling kill_block_super()
so that the assumption that generic_shutdown_super() can completely destroy
the dentry tree for there will be no external references holds true.

What was being done in the put_super() superblock op, is now done in the
kill_sb() filesystem op instead, prior to calling kill_block_super().

Changes made in [try #2]:

 (*) reiserfs_kill_sb() now checks that the superblock FS info pointer is set
     before trying to dereference it.
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: <reiserfs-dev@namesys.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/reiserfs/super.c

@@ -430,21 +430,30 @@ int remove_save_link(struct inode *inode, int truncate)
 	return journal_end(&th, inode->i_sb, JOURNAL_PER_BALANCE_CNT);
 }
 
-static void reiserfs_put_super(struct super_block *s)
+static void reiserfs_kill_sb(struct super_block *s)
 {
-	struct reiserfs_transaction_handle th;
-	th.t_trans_id = 0;
-
+	if (REISERFS_SB(s)) {
 		if (REISERFS_SB(s)->xattr_root) {
 			d_invalidate(REISERFS_SB(s)->xattr_root);
 			dput(REISERFS_SB(s)->xattr_root);
+			REISERFS_SB(s)->xattr_root = NULL;
 		}
 
 		if (REISERFS_SB(s)->priv_root) {
 			d_invalidate(REISERFS_SB(s)->priv_root);
 			dput(REISERFS_SB(s)->priv_root);
+			REISERFS_SB(s)->priv_root = NULL;
+		}
 	}
 
+	kill_block_super(s);
+}
+
+static void reiserfs_put_super(struct super_block *s)
+{
+	struct reiserfs_transaction_handle th;
+	th.t_trans_id = 0;
+
 	/* change file system state to current state if it was mounted with read-write permissions */
 	if (!(s->s_flags & MS_RDONLY)) {
 		if (!journal_begin(&th, s, 10)) {
@@ -2156,7 +2165,7 @@ struct file_system_type reiserfs_fs_type = {
 	.owner = THIS_MODULE,
 	.name = "reiserfs",
 	.get_sb = get_super_block,
-	.kill_sb = kill_block_super,
+	.kill_sb = reiserfs_kill_sb,
 	.fs_flags = FS_REQUIRES_DEV,
 };