ext4: Use generic_buffers_fsync_noflush() implementation

ext4 when got converted to iomap for dio, it copied __generic_file_fsync
implementation to avoid taking inode_lock in order to avoid any deadlock
(since iomap takes an inode_lock while calling generic_write_sync()).

The previous patch already added generic_buffers_fsync*() which does not
take any inode_lock(). Hence kill the redundant code and use
generic_buffers_fsync_noflush() function instead.

Tested-by: Disha Goel <disgoel@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <b43d4bb4403061ed86510c9587673e30a461ba14.1682069716.git.ritesh.list@gmail.com>

Author: riteshharjani

fs/ext4/fsync.c

@@ -28,6 +28,7 @@
 #include <linux/sched.h>
 #include <linux/writeback.h>
 #include <linux/blkdev.h>
+#include <linux/buffer_head.h>
 
 #include "ext4.h"
 #include "ext4_jbd2.h"
@@ -78,21 +79,13 @@ static int ext4_sync_parent(struct inode *inode)
 	return ret;
 }
 
-static int ext4_fsync_nojournal(struct inode *inode, bool datasync,
-				bool *needs_barrier)
+static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
+				int datasync, bool *needs_barrier)
 {
-	int ret, err;
-
-	ret = sync_mapping_buffers(inode->i_mapping);
-	if (!(inode->i_state & I_DIRTY_ALL))
-		return ret;
-	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
-		return ret;
-
-	err = sync_inode_metadata(inode, 1);
-	if (!ret)
-		ret = err;
+	struct inode *inode = file->f_inode;
+	int ret;
 
+	ret = generic_buffers_fsync_noflush(file, start, end, datasync);
 	if (!ret)
 		ret = ext4_sync_parent(inode);
 	if (test_opt(inode->i_sb, BARRIER))
@@ -148,6 +141,14 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 		goto out;
 	}
 
+	if (!sbi->s_journal) {
+		ret = ext4_fsync_nojournal(file, start, end, datasync,
+					   &needs_barrier);
+		if (needs_barrier)
+			goto issue_flush;
+		goto out;
+	}
+
 	ret = file_write_and_wait_range(file, start, end);
 	if (ret)
 		goto out;
@@ -157,11 +158,9 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	 *  Metadata is in the journal, we wait for proper transaction to
 	 *  commit here.
 	 */
-	if (!sbi->s_journal)
-		ret = ext4_fsync_nojournal(inode, datasync, &needs_barrier);
-	else
-		ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
+	ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
 
+issue_flush:
 	if (needs_barrier) {
 		err = blkdev_issue_flush(inode->i_sb->s_bdev);
 		if (!ret)