ocfs2: no need get dinode bh when zeroing extend

Since di_bh won't be used when zeroing extend, set it to NULL.
Signed-off-by: NJoseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/aops.c

@@ -706,7 +706,7 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
 	}
 
 	if (append_write) {
-		ret = ocfs2_inode_lock(inode, &di_bh, 1);
+		ret = ocfs2_inode_lock(inode, NULL, 1);
 		if (ret < 0) {
 			mlog_errno(ret);
 			goto clean_orphan;
@@ -720,7 +720,6 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
 		if (ret < 0) {
 			mlog_errno(ret);
 			ocfs2_inode_unlock(inode, 1);
-			brelse(di_bh);
 			goto clean_orphan;
 		}
 
@@ -728,13 +727,10 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
 		if (is_overwrite < 0) {
 			mlog_errno(is_overwrite);
 			ocfs2_inode_unlock(inode, 1);
-			brelse(di_bh);
 			goto clean_orphan;
 		}
 
 		ocfs2_inode_unlock(inode, 1);
-		brelse(di_bh);
-		di_bh = NULL;
 	}
 
 	written = __blockdev_direct_IO(WRITE, iocb, inode, inode->i_sb->s_bdev,