Re: [Virtio-fs] [PATCH v4 6/8] fuse: mark inode DONT_CACHE when per-file DAX indication changes

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Jeffle Xu (jefflexu@linux.alibaba.com) wrote:
> When the per-file DAX indication changes while the file is still
> *opened*, it is quite complicated and maybe fragile to dynamically
> change the DAX state.
> 
> Hence mark the inode and corresponding dentries as DONE_CACHE once the

                                                     ^^^^^^^^^^
typo as DONT ?

Dave

> per-file DAX indication changes, so that the inode instance will be
> evicted and freed as soon as possible once the file is closed and the
> last reference to the inode is put. And then when the file gets reopened
> next time, the inode will reflect the new DAX state.
> 
> In summary, when the per-file DAX indication 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@linux.alibaba.com>
> ---
>  fs/fuse/dax.c    | 9 +++++++++
>  fs/fuse/fuse_i.h | 1 +
>  fs/fuse/inode.c  | 3 +++
>  3 files changed, 13 insertions(+)
> 
> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
> index 30833f8d37dd..f7ede0be4e00 100644
> --- a/fs/fuse/dax.c
> +++ b/fs/fuse/dax.c
> @@ -1364,6 +1364,15 @@ void fuse_dax_inode_init(struct inode *inode, unsigned int flags)
>  	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_mode == FUSE_DAX_INODE &&
> +	    fc->perfile_dax && (!!IS_DAX(inode) != newdax))
> +		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/fuse_i.h b/fs/fuse/fuse_i.h
> index 7b7b4c208af2..56fe1c4d2136 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -1260,6 +1260,7 @@ 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, 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 8080f78befed..8c9774c6a210 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)
> -- 
> 2.27.0
> 
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-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK