Re: [PATCH V7 17/19] famfs_fuse: Add DAX address_space_operations with noop_dirty_folio

Joanne Koong
2026-01-30T23:13:32Z

On Sun, Jan 18, 2026 at 2:33 PM John Groves <john@jagalactic.com> wrote:
>
> 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>

Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
> ---
> fs/fuse/famfs.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/fs/fuse/famfs.c b/fs/fuse/famfs.c
> index b38e92d8f381..90325bd14354 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,
> +};
> +
> /*****************************************************************************/
>
> /*
> @@ -627,6 +637,7 @@ 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);
> --
> 2.52.0
>
>