ocfs2: fix a tiny race when truncate dio orohaned entry

Once dio crashed it will leave an entry in orphan dir.  And orphan scan
will take care of the clean up.  There is a tiny race case that the same
entry will be truncated twice and then trigger the BUG in
ocfs2_del_inode_from_orphan.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/namei.c

@@ -2670,30 +2670,22 @@ bail:
 }
 
 int ocfs2_del_inode_from_orphan(struct ocfs2_super *osb,
-		struct inode *inode, int update_isize,
-		loff_t end)
+		struct inode *inode, struct buffer_head *di_bh,
+		int update_isize, loff_t end)
 {
 	struct inode *orphan_dir_inode = NULL;
 	struct buffer_head *orphan_dir_bh = NULL;
-	struct buffer_head *di_bh = NULL;
-	struct ocfs2_dinode *di = NULL;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
 	handle_t *handle = NULL;
 	int status = 0;
 
-	status = ocfs2_inode_lock(inode, &di_bh, 1);
-	if (status < 0) {
-		mlog_errno(status);
-		goto bail;
-	}
-	di = (struct ocfs2_dinode *) di_bh->b_data;
-
 	orphan_dir_inode = ocfs2_get_system_file_inode(osb,
 			ORPHAN_DIR_SYSTEM_INODE,
 			le16_to_cpu(di->i_dio_orphaned_slot));
 	if (!orphan_dir_inode) {
 		status = -ENOENT;
 		mlog_errno(status);
-		goto bail_unlock_inode;
+		goto bail;
 	}
 
 	mutex_lock(&orphan_dir_inode->i_mutex);
@@ -2702,7 +2694,7 @@ int ocfs2_del_inode_from_orphan(struct ocfs2_super *osb,
 		mutex_unlock(&orphan_dir_inode->i_mutex);
 		iput(orphan_dir_inode);
 		mlog_errno(status);
-		goto bail_unlock_inode;
+		goto bail;
 	}
 
 	handle = ocfs2_start_trans(osb,
@@ -2749,10 +2741,6 @@ bail_unlock_orphan:
 	brelse(orphan_dir_bh);
 	iput(orphan_dir_inode);
 
-bail_unlock_inode:
-	ocfs2_inode_unlock(inode, 1);
-	brelse(di_bh);
-
 bail:
 	return status;
 }