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>

3 files changed, 31 insertions, 2 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 784f2c72c992..46e0d4e857c7 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);
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 7e39cd654834..8490c64d34fe 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -500,6 +500,14 @@ static inline int ocfs2_writes_unwritten_extents(struct ocfs2_super *osb)
         return 0;
 }
 
+static inline int ocfs2_supports_append_dio(struct ocfs2_super *osb)
+{
+        if (osb->s_feature_ro_compat & OCFS2_FEATURE_RO_COMPAT_APPEND_DIO)
+                return 1;
+        return 0;
+}
+
+
 static inline int ocfs2_supports_inline_data(struct ocfs2_super *osb)
 {
         if (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_INLINE_DATA)
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index cf4fa43af78e..20e37a3ed26f 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -105,7 +105,8 @@
                                          | OCFS2_FEATURE_INCOMPAT_CLUSTERINFO)
 #define OCFS2_FEATURE_RO_COMPAT_SUPP    (OCFS2_FEATURE_RO_COMPAT_UNWRITTEN \
                                          | OCFS2_FEATURE_RO_COMPAT_USRQUOTA \
-                                         | OCFS2_FEATURE_RO_COMPAT_GRPQUOTA)
+                                         | OCFS2_FEATURE_RO_COMPAT_GRPQUOTA \
+                                         | OCFS2_FEATURE_RO_COMPAT_APPEND_DIO)
 
 /*
  * Heartbeat-only devices are missing journals and other files.  The
@@ -199,6 +200,11 @@
 #define OCFS2_FEATURE_RO_COMPAT_USRQUOTA        0x0002
 #define OCFS2_FEATURE_RO_COMPAT_GRPQUOTA        0x0004
 
+/*
+ * Append Direct IO support
+ */
+#define OCFS2_FEATURE_RO_COMPAT_APPEND_DIO      0x0008
+
 /* The byte offset of the first backup block will be 1G.
  * The following will be 4G, 16G, 64G, 256G and 1T.
  */