gfs2: merge gfs2_writeback_aops and gfs2_ordered_aops

The only difference between the two is that gfs2_ordered_aops sets the
set_page_dirty method to __set_page_dirty_buffers, but given that
__set_page_dirty_buffers is the default, if no method is set, there is no need
to to do that.  Merge the two sets of operations into one.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/aops.c

@@ -847,7 +847,7 @@ int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 	return 0;
 }
 
-static const struct address_space_operations gfs2_writeback_aops = {
+static const struct address_space_operations gfs2_aops = {
 	.writepage = gfs2_writepage,
 	.writepages = gfs2_writepages,
 	.readpage = gfs2_readpage,
@@ -861,21 +861,6 @@ static const struct address_space_operations gfs2_writeback_aops = {
 	.error_remove_page = generic_error_remove_page,
 };
 
-static const struct address_space_operations gfs2_ordered_aops = {
-	.writepage = gfs2_writepage,
-	.writepages = gfs2_writepages,
-	.readpage = gfs2_readpage,
-	.readpages = gfs2_readpages,
-	.set_page_dirty = __set_page_dirty_buffers,
-	.bmap = gfs2_bmap,
-	.invalidatepage = gfs2_invalidatepage,
-	.releasepage = gfs2_releasepage,
-	.direct_IO = noop_direct_IO,
-	.migratepage = buffer_migrate_page,
-	.is_partially_uptodate = block_is_partially_uptodate,
-	.error_remove_page = generic_error_remove_page,
-};
-
 static const struct address_space_operations gfs2_jdata_aops = {
 	.writepage = gfs2_jdata_writepage,
 	.writepages = gfs2_jdata_writepages,
@@ -891,15 +876,8 @@ static const struct address_space_operations gfs2_jdata_aops = {
 
 void gfs2_set_aops(struct inode *inode)
 {
-	struct gfs2_inode *ip = GFS2_I(inode);
-	struct gfs2_sbd *sdp = GFS2_SB(inode);
-
-	if (gfs2_is_jdata(ip))
+	if (gfs2_is_jdata(GFS2_I(inode)))
 		inode->i_mapping->a_ops = &gfs2_jdata_aops;
-	else if (gfs2_is_writeback(sdp))
-		inode->i_mapping->a_ops = &gfs2_writeback_aops;
-	else if (gfs2_is_ordered(sdp))
-		inode->i_mapping->a_ops = &gfs2_ordered_aops;
 	else
-		BUG();
+		inode->i_mapping->a_ops = &gfs2_aops;
 }