On Tue, Nov 02, 2021 at 01:26:02PM +0800, Jeffle Xu wrote:
> Among the FUSE_INIT phase, client shall advertise per inode DAX if it's
> mounted with "dax=inode". Then server is aware that client is in per
> inode DAX mode, and will construct per-inode DAX attribute accordingly.
>
> Server shall also advertise support for per inode DAX. If server doesn't
> support it while client is mounted with "dax=inode", client will
> silently fallback to "dax=never" since "dax=inode" is advisory only.
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> ---
> fs/fuse/dax.c | 2 +-
> fs/fuse/fuse_i.h | 3 +++
> fs/fuse/inode.c | 16 +++++++++++++---
> 3 files changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
> index 8a328fb20dcb..c8ee601b94b8 100644
> --- a/fs/fuse/dax.c
> +++ b/fs/fuse/dax.c
> @@ -1350,7 +1350,7 @@ static bool fuse_should_enable_dax(struct inode *inode, unsigned int flags)
> return true;
>
> /* dax_mode is FUSE_DAX_INODE or FUSE_DAX_NONE */
> - return flags & FUSE_ATTR_DAX;
> + return fc->inode_dax && (flags & FUSE_ATTR_DAX);
> }
>
> void fuse_dax_inode_init(struct inode *inode, unsigned int flags)
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 055b39430540..58e54b5a4d65 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -777,6 +777,9 @@ struct fuse_conn {
> /* Propagate syncfs() to server */
> unsigned int sync_fs:1;
>
> + /* Does the filesystem support per inode DAX? */
> + unsigned int inode_dax:1;
> +
> /** The number of requests waiting for completion */
> atomic_t num_waiting;
>
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index acba14002d04..0512d8cb36c3 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -1136,11 +1136,19 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
> min_t(unsigned int, fc->max_pages_limit,
> max_t(unsigned int, arg->max_pages, 1));
> }
> - if (IS_ENABLED(CONFIG_FUSE_DAX) &&
> - arg->flags & FUSE_MAP_ALIGNMENT &&
> +#ifdef CONFIG_FUSE_DAX
> + if ((arg->flags & FUSE_HAS_INODE_DAX) &&
> + fuse_is_inode_dax_mode(fc->dax_mode)) {
Why do we call fuse_is_inode_dax_mode() here? While sending INIT request
we set FUSE_HAS_INODE_DAX only if fuse_is_inode_dax_mode() is true. So
we should not have to call it again when server replies.?
> + fc->inode_dax = 1;
> + }
> + if (arg->flags & FUSE_MAP_ALIGNMENT &&
> !fuse_dax_check_alignment(fc, arg->map_alignment)) {
> - ok = false;
> + if (fuse_is_inode_dax_mode(fc->dax_mode))
> + fc->inode_dax = 0;
If mapping alignment is not right, I guess we can fail (even in case
of dax=inode). In this case client wants per dax inode, server supports
it but alignment is wrong. I think that should be an error and user should
fix it. IMHO, just leave this code path in place and we will error out.
Thanks
Vivek
> + else
> + ok = false;
> }
> +#endif
> if (arg->flags & FUSE_HANDLE_KILLPRIV_V2) {
> fc->handle_killpriv_v2 = 1;
> fm->sb->s_flags |= SB_NOSEC;
> @@ -1194,6 +1202,8 @@ void fuse_send_init(struct fuse_mount *fm)
> #ifdef CONFIG_FUSE_DAX
> if (fm->fc->dax)
> ia->in.flags |= FUSE_MAP_ALIGNMENT;
> + if (fuse_is_inode_dax_mode(fm->fc->dax_mode))
> + ia->in.flags |= FUSE_HAS_INODE_DAX;
> #endif
> if (fm->fc->auto_submounts)
> ia->in.flags |= FUSE_SUBMOUNTS;
> --
> 2.27.0
>
