[PATCH V8 08/10] famfs_fuse: Add DAX address_space_operations with noop_dirty_folio

John Groves
2026-03-19T13:20:18Z

From: John Groves <John@Groves.net>

Famfs is memory-backed; there is no place to write back to, and no
reason to mark pages dirty at all.

Signed-off-by: John Groves <john@groves.net>
---
fs/fuse/famfs.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/fs/fuse/famfs.c b/fs/fuse/famfs.c
index 87012df537eb..121ed74e9727 100644
--- a/fs/fuse/famfs.c
+++ b/fs/fuse/famfs.c
@@ -14,6 +14,7 @@
#include <linux/mm.h>
#include <linux/dax.h>
#include <linux/iomap.h>
+#include <linux/pagemap.h>
#include <linux/path.h>
#include <linux/namei.h>
#include <linux/string.h>
@@ -39,6 +40,15 @@ static const struct dax_holder_operations famfs_fuse_dax_holder_ops = {
.notify_failure = famfs_dax_notify_failure,
};

+/*
+ * DAX address_space_operations for famfs.
+ * famfs doesn't need dirty tracking - writes go directly to
+ * memory with no writeback required.
+ */
+static const struct address_space_operations famfs_dax_aops = {
+ .dirty_folio = noop_dirty_folio,
+};
+
/*****************************************************************************/

/*
@@ -624,6 +634,7 @@ famfs_file_init_dax(
if (famfs_meta_set(fi, meta) == NULL) {
i_size_write(inode, meta->file_size);
inode->i_flags |= S_DAX;
+ inode->i_data.a_ops = &famfs_dax_aops;
} else {
pr_debug("%s: file already had metadata\n", __func__);
__famfs_meta_free(meta);
--
2.53.0