On Thu, Jul 15, 2021 at 05:30:31PM +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.
>
> Currently it is not implemented yet to change per-file DAX flag inside
> guest kernel, e.g., by chattr(1).
Thanks for the patch, it looks good to me.
I think it's a good starting point, what I'd like to discuss here is
whether we're going to let chattr to toggle the dax flag.
My usecase is like, on the fuse server side, if a file is marked as
DAX, then it won't change any more. So this 'fuse_attr.flags' works
for me at least.
thanks,
liubo
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> ---
> fs/fuse/dax.c | 28 ++++++++++++++++++++++++----
> fs/fuse/file.c | 4 ++--
> fs/fuse/fuse_i.h | 5 +++--
> fs/fuse/inode.c | 4 +++-
> include/uapi/linux/fuse.h | 5 +++++
> 5 files changed, 37 insertions(+), 9 deletions(-)
>
> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
> index 4873d764cb66..ed5a430364bb 100644
> --- a/fs/fuse/dax.c
> +++ b/fs/fuse/dax.c
> @@ -1341,7 +1341,7 @@ static const struct address_space_operations fuse_dax_file_aops = {
> .invalidatepage = noop_invalidatepage,
> };
>
> -static bool fuse_should_enable_dax(struct inode *inode)
> +static bool fuse_should_enable_dax(struct inode *inode, unsigned int flags)
> {
> struct fuse_conn *fc = get_fuse_conn(inode);
> unsigned int mode;
> @@ -1354,18 +1354,38 @@ static bool fuse_should_enable_dax(struct inode *inode)
> if (mode == FUSE_DAX_MOUNT_NEVER)
> return false;
>
> - return true;
> + if (mode == FUSE_DAX_MOUNT_ALWAYS)
> + return true;
> +
> + WARN_ON(mode != FUSE_DAX_MOUNT_INODE);
> + return flags & FUSE_ATTR_DAX;
> }
>
> -void fuse_dax_inode_init(struct inode *inode)
> +void fuse_dax_inode_init(struct inode *inode, unsigned int flags)
> {
> - if (!fuse_should_enable_dax(inode))
> + if (!fuse_should_enable_dax(inode, flags))
> return;
>
> inode->i_flags |= S_DAX;
> inode->i_data.a_ops = &fuse_dax_file_aops;
> }
>
> +void fuse_update_dax(struct inode *inode, unsigned int flags)
> +{
> + bool oldstate, newstate;
> + struct fuse_conn *fc = get_fuse_conn(inode);
> +
> + if (!IS_ENABLED(CONFIG_FUSE_DAX) || !fc->dax ||
> + fc->dax->mode != FUSE_DAX_MOUNT_INODE)
> + return;
> +
> + oldstate = IS_DAX(inode);
> + newstate = flags & FUSE_ATTR_DAX;
> +
> + if (oldstate != newstate)
> + d_mark_dontcache(inode);
> +}
> +
> bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment)
> {
> if (fc->dax && (map_alignment > FUSE_DAX_SHIFT)) {
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 97f860cfc195..cf42af492146 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -3142,7 +3142,7 @@ static const struct address_space_operations fuse_file_aops = {
> .write_end = fuse_write_end,
> };
>
> -void fuse_init_file_inode(struct inode *inode)
> +void fuse_init_file_inode(struct inode *inode, struct fuse_attr *attr)
> {
> struct fuse_inode *fi = get_fuse_inode(inode);
>
> @@ -3156,5 +3156,5 @@ void fuse_init_file_inode(struct inode *inode)
> fi->writepages = RB_ROOT;
>
> if (IS_ENABLED(CONFIG_FUSE_DAX))
> - fuse_dax_inode_init(inode);
> + fuse_dax_inode_init(inode, attr->flags);
> }
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index f29018323845..b0ecfffd0c7d 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -1000,7 +1000,7 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
> /**
> * Initialize file operations on a regular file
> */
> -void fuse_init_file_inode(struct inode *inode);
> +void fuse_init_file_inode(struct inode *inode, struct fuse_attr *attr);
>
> /**
> * Initialize inode operations on regular files and special files
> @@ -1252,8 +1252,9 @@ int fuse_dax_conn_alloc(struct fuse_conn *fc, unsigned int mode,
> struct dax_device *dax_dev);
> void fuse_dax_conn_free(struct fuse_conn *fc);
> bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi);
> -void fuse_dax_inode_init(struct inode *inode);
> +void fuse_dax_inode_init(struct inode *inode, unsigned int flags);
> void fuse_dax_inode_cleanup(struct inode *inode);
> +void fuse_update_dax(struct inode *inode, unsigned int flags);
> bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment);
> void fuse_dax_cancel_work(struct fuse_conn *fc);
>
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index f6b46395edb2..47ebb1a394d2 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -269,6 +269,8 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
> if (inval)
> invalidate_inode_pages2(inode->i_mapping);
> }
> +
> + fuse_update_dax(inode, attr->flags);
> }
>
> static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
> @@ -281,7 +283,7 @@ static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
> inode->i_ctime.tv_nsec = attr->ctimensec;
> if (S_ISREG(inode->i_mode)) {
> fuse_init_common(inode);
> - fuse_init_file_inode(inode);
> + fuse_init_file_inode(inode, attr);
> } else if (S_ISDIR(inode->i_mode))
> fuse_init_dir(inode);
> else if (S_ISLNK(inode->i_mode))
> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> index 36ed092227fa..9ee088ddbe2a 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)
>
> /**
> * Open flags
> --
> 2.27.0
