[RFC PATCH 08/18] ext4: add a new iomap aops for regular file's buffered IO path

[Zhang Yi <yi.zhang@huaweicloud.com>]

From: Zhang Yi <yi.zhang@huawei.com>

Introduce a new iomap address space operations ext4_iomap_aops that used
to support regular file's buffered IO path. Most of their callbacks have
already been implemented yet, the .read_folio, .readahead and
.writepages should be implemented later.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/ext4/inode.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e92b205b3b24..4eef3828d5fd 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3525,6 +3525,22 @@ const struct iomap_ops ext4_iomap_report_ops = {
 	.iomap_begin = ext4_iomap_begin_report,
 };
 
+static int ext4_iomap_read_folio(struct file *file, struct folio *folio)
+{
+	return 0;
+}
+
+static void ext4_iomap_readahead(struct readahead_control *rac)
+{
+
+}
+
+static int ext4_iomap_writepages(struct address_space *mapping,
+				 struct writeback_control *wbc)
+{
+	return 0;
+}
+
 /*
  * For data=journal mode, folio should be marked dirty only when it was
  * writeably mapped. When that happens, it was already attached to the
@@ -3614,6 +3630,21 @@ static const struct address_space_operations ext4_da_aops = {
 	.swap_activate		= ext4_iomap_swap_activate,
 };
 
+static const struct address_space_operations ext4_iomap_aops = {
+	.read_folio		= ext4_iomap_read_folio,
+	.readahead		= ext4_iomap_readahead,
+	.writepages		= ext4_iomap_writepages,
+	.dirty_folio		= iomap_dirty_folio,
+	.bmap			= ext4_bmap,
+	.invalidate_folio	= iomap_invalidate_folio,
+	.release_folio		= iomap_release_folio,
+	.direct_IO		= noop_direct_IO,
+	.migrate_folio		= filemap_migrate_folio,
+	.is_partially_uptodate  = iomap_is_partially_uptodate,
+	.error_remove_page	= generic_error_remove_page,
+	.swap_activate		= ext4_iomap_swap_activate,
+};
+
 static const struct address_space_operations ext4_dax_aops = {
 	.writepages		= ext4_dax_writepages,
 	.direct_IO		= noop_direct_IO,
-- 
2.39.2