exofs: exofs_file_fsync and exofs_file_flush correctness

As per Christoph advise: no need to call filemap_write_and_wait().
In exofs all metadata is at the inode so just writing the inode is
all is needed. ->fsync implies this must be done synchronously.

But now exofs_file_fsync can not be used by exofs_file_flush.
vfs_fsync() should do that job correctly.

FIXME: remove the sb_sync and fix that sb_update better.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

fs/exofs/file.c

@@ -30,9 +30,6 @@
  * along with exofs; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
-
-#include <linux/buffer_head.h>
-
 #include "exofs.h"
 
 static int exofs_release_file(struct inode *inode, struct file *filp)
@@ -40,19 +37,27 @@ static int exofs_release_file(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+/* exofs_file_fsync - flush the inode to disk
+ *
+ *   Note, in exofs all metadata is written as part of inode, regardless.
+ *   The writeout is synchronous
+ */
 static int exofs_file_fsync(struct file *filp, int datasync)
 {
 	int ret;
-	struct address_space *mapping = filp->f_mapping;
-	struct inode *inode = mapping->host;
+	struct inode *inode = filp->f_mapping->host;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_ALL,
+		.nr_to_write = 0, /* metadata-only; caller takes care of data */
+	};
 	struct super_block *sb;
 
-	ret = filemap_write_and_wait(mapping);
-	if (ret)
-		return ret;
+	if (!(inode->i_state & I_DIRTY))
+		return 0;
+	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
+		return 0;
 
-	/* sync the inode attributes */
-	ret = write_inode_now(inode, 1);
+	ret = sync_inode(inode, &wbc);
 
 	/* This is a good place to write the sb */
 	/* TODO: Sechedule an sb-sync on create */
@@ -65,9 +70,9 @@ static int exofs_file_fsync(struct file *filp, int datasync)
 
 static int exofs_flush(struct file *file, fl_owner_t id)
 {
-	exofs_file_fsync(file, 1);
+	int ret = vfs_fsync(file, 0);
 	/* TODO: Flush the OSD target */
-	return 0;
+	return ret;
 }
 
 const struct file_operations exofs_file_operations = {