ocfs2: set append dio as a ro compat feature

Intruduce a bit OCFS2_FEATURE_RO_COMPAT_APPEND_DIO and check it in
write flow. If the bit is not set, fall back to the old way.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Weiwei Wang <wangww631@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Xuejiufei <xuejiufei@huawei.com>
Cc: alex chen <alex.chen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 784f2c7..46e0d4e 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2213,6 +2213,15 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
 		}
 
 		/*
+		 * Fallback to old way if the feature bit is not set.
+		 */
+		if (end > i_size_read(inode) &&
+				!ocfs2_supports_append_dio(osb)) {
+			*direct_io = 0;
+			break;
+		}
+
+		/*
 		 * We don't fill holes during direct io, so
 		 * check for them here. If any are found, the
 		 * caller will have to retake some cluster
@@ -2220,7 +2229,13 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
 		 */
 		ret = ocfs2_check_range_for_holes(inode, saved_pos, count);
 		if (ret == 1) {
-			*direct_io = 0;
+			/*
+			 * Fallback to old way if the feature bit is not set.
+			 * Otherwise try dio first and then complete the rest
+			 * request through buffer io.
+			 */
+			if (!ocfs2_supports_append_dio(osb))
+				*direct_io = 0;
 			ret = 0;
 		} else if (ret < 0)
 			mlog_errno(ret);