ocfs2: fix several issues of append dio

1) Take rw EX lock in case of append dio.
2) Explicitly treat the error code -EIOCBQUEUED as normal.
3) Set di_bh to NULL after brelse if it may be used again later.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Yiwen Jiang <jiangyiwen@huawei.com>
Cc: Weiwei Wang <wangww631@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>
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 1e88ff4..b36dcad 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -860,7 +860,8 @@
 	written = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
 				       offset, ocfs2_direct_IO_get_blocks,
 				       ocfs2_dio_end_io, NULL, 0);
-	if (unlikely(written < 0)) {
+	/* overwrite aio may return -EIOCBQUEUED, and it is not an error */
+	if ((written < 0) && (written != -EIOCBQUEUED)) {
 		loff_t i_size = i_size_read(inode);
 
 		if (offset + count > i_size) {
@@ -879,12 +880,14 @@
 
 					ocfs2_inode_unlock(inode, 1);
 					brelse(di_bh);
+					di_bh = NULL;
 					goto clean_orphan;
 				}
 			}
 
 			ocfs2_inode_unlock(inode, 1);
 			brelse(di_bh);
+			di_bh = NULL;
 
 			ret = jbd2_journal_force_commit(journal);
 			if (ret < 0)
@@ -939,10 +942,12 @@
 		if (tmp_ret < 0) {
 			ret = tmp_ret;
 			mlog_errno(ret);
+			brelse(di_bh);
 			goto out;
 		}
 
 		ocfs2_inode_unlock(inode, 1);
+		brelse(di_bh);
 
 		tmp_ret = jbd2_journal_force_commit(journal);
 		if (tmp_ret < 0) {