ext2: set FMODE_CAN_ODIRECT instead of a dummy direct_IO method

Since commit a2ad63da ("VFS: add FMODE_CAN_ODIRECT file flag") file
systems can just set the FMODE_CAN_ODIRECT flag at open time instead of
wiring up a dummy direct_IO method to indicate support for direct I/O.
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <94f78492f55c3f421359fb6e0d8fab6e79ea17b2.1709215665.git.ritesh.list@gmail.com>

fs/ext2/file.c

@@ -302,6 +302,12 @@ static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	return generic_file_write_iter(iocb, from);
 }
 
+static int ext2_file_open(struct inode *inode, struct file *filp)
+{
+	filp->f_mode |= FMODE_CAN_ODIRECT;
+	return dquot_file_open(inode, filp);
+}
+
 const struct file_operations ext2_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read_iter	= ext2_file_read_iter,
@@ -311,7 +317,7 @@ const struct file_operations ext2_file_operations = {
 	.compat_ioctl	= ext2_compat_ioctl,
 #endif
 	.mmap		= ext2_file_mmap,
-	.open		= dquot_file_open,
+	.open		= ext2_file_open,
 	.release	= ext2_release_file,
 	.fsync		= ext2_fsync,
 	.get_unmapped_area = thp_get_unmapped_area,

fs/ext2/inode.c

@@ -965,7 +965,6 @@ const struct address_space_operations ext2_aops = {
 	.write_begin		= ext2_write_begin,
 	.write_end		= ext2_write_end,
 	.bmap			= ext2_bmap,
-	.direct_IO		= noop_direct_IO,
 	.writepages		= ext2_writepages,
 	.migrate_folio		= buffer_migrate_folio,
 	.is_partially_uptodate	= block_is_partially_uptodate,
@@ -974,7 +973,6 @@ const struct address_space_operations ext2_aops = {
 
 static const struct address_space_operations ext2_dax_aops = {
 	.writepages		= ext2_dax_writepages,
-	.direct_IO		= noop_direct_IO,
 	.dirty_folio		= noop_dirty_folio,
 };