[Virtio-fs] [PATCH v6 3/7] fuse: support per-file DAX in fuse protocol

[Vivek Goyal]

On Wed, Oct 20, 2021 at 11:04:03AM +0800, JeffleXu wrote:
> 
> 
> On 10/18/21 10:20 PM, Vivek Goyal wrote:
> > On Mon, Oct 18, 2021 at 10:14:04AM -0400, Vivek Goyal wrote:
> >> On Mon, Oct 11, 2021 at 11:00:48AM +0800, Jeffle Xu wrote:
> >>> Expand the fuse protocol to support per-file DAX.
> >>>
> >>> FUSE_PERFILE_DAX flag is added indicating if fuse server/client
> >>
> >> Should we call this flag FUSE_INODE_DAX instead? It is per inode property?
> >>
> 
> Yes, strictly specking, 'per-file' is not correct.
> 
> > 
> > I realized that you are using FUSE_DAX_INODE to represent dax mode. So it
> > will be confusing to use FUSE_INODE_DAX as protocol flag. How about
> > FUSE_INODE_DAX_STATE instead?
> > 
> 
> Emmm, the "_STATE" suffix is not straightforward and clear to me. How
> about FUSE_HAS_INODE_DAX or FUSE_DO_INODE_DAX, referring to the existing
> 'FUSE_HAS_IOCTL_DIR' and 'FUSE_DO_READDIRPLUS'?

FUSE_HAS_INODE_DAX or FUSE_DO_INODE_DAX are fine.

Vivek

> 
> 
> >>
> >>> supporting per-file DAX. It can be conveyed in both FUSE_INIT request
> >>> and reply.
> >>>
> >>> FUSE_ATTR_DAX flag is added indicating if DAX shall be enabled for
> >>> corresponding file. It is conveyed in FUSE_LOOKUP reply.
> >>>
> >>> Signed-off-by: Jeffle Xu <jefflexu at linux.alibaba.com>
> >>> ---
> >>>  include/uapi/linux/fuse.h | 9 ++++++++-
> >>>  1 file changed, 8 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> >>> index 36ed092227fa..15a1f5fc0797 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_PERFILE_DAX, FUSE_ATTR_DAX
> >>>   */
> >>>  
> >>>  #ifndef _LINUX_FUSE_H
> >>> @@ -219,7 +222,7 @@
> >>>  #define FUSE_KERNEL_VERSION 7
> >>>  
> >>>  /** Minor version number of this interface */
> >>> -#define FUSE_KERNEL_MINOR_VERSION 34
> >>> +#define FUSE_KERNEL_MINOR_VERSION 35
> >>>  
> >>>  /** The node ID of the root inode */
> >>>  #define FUSE_ROOT_ID 1
> >>> @@ -336,6 +339,7 @@ struct fuse_file_lock {
> >>>   *			write/truncate sgid is killed only if file has group
> >>>   *			execute permission. (Same as Linux VFS behavior).
> >>>   * FUSE_SETXATTR_EXT:	Server supports extended struct fuse_setxattr_in
> >>> + * FUSE_PERFILE_DAX:	kernel supports per-file DAX
> >>>   */
> >>>  #define FUSE_ASYNC_READ		(1 << 0)
> >>>  #define FUSE_POSIX_LOCKS	(1 << 1)
> >>> @@ -367,6 +371,7 @@ struct fuse_file_lock {
> >>>  #define FUSE_SUBMOUNTS		(1 << 27)
> >>>  #define FUSE_HANDLE_KILLPRIV_V2	(1 << 28)
> >>>  #define FUSE_SETXATTR_EXT	(1 << 29)
> >>> +#define FUSE_PERFILE_DAX	(1 << 30)
> >>>  
> >>>  /**
> >>>   * CUSE INIT request/reply flags
> >>> @@ -449,8 +454,10 @@ 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
> >>>
> 
> -- 
> Thanks,
> Jeffle
>