On Fri, Jul 16, 2021 at 06:47:52PM +0800, Jeffle Xu wrote:
> Add one flag for fuse_attr.flags indicating if DAX shall be enabled for
> this file.
>
> When the per-file DAX flag changes for an *opened* file, the state of
> the file won't be updated until this file is closed and reopened later.
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
[..]
> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> index 36ed092227fa..90c9df10d37a 100644
> --- a/include/uapi/linux/fuse.h
> +++ b/include/uapi/linux/fuse.h
> @@ -184,6 +184,9 @@
> *
> * 7.34
> * - add FUSE_SYNCFS
> + *
> + * 7.35
> + * - add FUSE_ATTR_DAX
> */
>
> #ifndef _LINUX_FUSE_H
> @@ -449,8 +452,10 @@ struct fuse_file_lock {
> * fuse_attr flags
> *
> * FUSE_ATTR_SUBMOUNT: Object is a submount root
> + * FUSE_ATTR_DAX: Enable DAX for this file in per-file DAX mode
> */
> #define FUSE_ATTR_SUBMOUNT (1 << 0)
> +#define FUSE_ATTR_DAX (1 << 1)
Generic fuse changes (addition of FUSE_ATTR_DAX) should probably in
a separate patch.
I am not clear on one thing. If we are planning to rely on persistent
inode attr (FS_XFLAG_DAX as per Documentation/filesystems/dax.rst), then
why fuse server needs to communicate the state of that attr using a
flag? Can client directly query it? I am not sure where at these
attrs stored and if fuse protocol currently supports it.
What about flag STATX_ATTR_DAX. We probably should report that too
in stat if we are using dax on the inode?
Vivek
