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 at linux.alibaba.com>
> ---
> fs/fuse/dax.c | 21 +++++++++++++++++----
> fs/fuse/file.c | 4 ++--
> fs/fuse/fuse_i.h | 5 +++--
> fs/fuse/inode.c | 5 ++++-
> include/uapi/linux/fuse.h | 5 +++++
> 5 files changed, 31 insertions(+), 9 deletions(-)
>
> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
> index a478e824c2d0..0e862119757a 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 +1354,31 @@ 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_dax_dontcache(struct inode *inode, bool newdax)
> +{
> + struct fuse_conn *fc = get_fuse_conn(inode);
> +
> + if (fc->dax && fc->dax->mode == FUSE_DAX_MOUNT_INODE
&&
> + IS_DAX(inode) != newdax)
> + d_mark_dontcache(inode);
> +}
> +
This capability to mark an inode dontcache should probably be in a
separate patch. These seem to logically two functionalities. One is
enabling DAX on an inode. And second is making sure how soon you
see the effect of that change and hence marking inode dontcache.
Not sure how useful this is. In cache=none mode we should get rid of
inode ASAP. In cache=auto mode we will get rid of after 1 second (or
after a user specified timeout). So only place this seems to be
useful is cache=always.
Vivek
> 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..0793b93d680a 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_dax_dontcache(struct inode *inode, bool newdax);
> 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..2ae92798126e 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -269,6 +269,9 @@ void fuse_change_attributes(struct inode *inode, struct
fuse_attr *attr,
> if (inval)
> invalidate_inode_pages2(inode->i_mapping);
> }
> +
> + if (IS_ENABLED(CONFIG_FUSE_DAX))
> + fuse_dax_dontcache(inode, attr->flags & FUSE_ATTR_DAX);
> }
>
> static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
> @@ -281,7 +284,7 @@ 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..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)
>
> /**
> * Open flags
> --
> 2.27.0
>