[Virtio-fs] [virtiofsd PATCH v6 6/6] virtiofsd: implement persistent inode attribute based dax policy
Vivek Goyal
vgoyal at redhat.com
Wed Oct 20 17:55:45 UTC 2021
On Mon, Oct 11, 2021 at 11:09:38AM +0800, Jeffle Xu wrote:
> The per-file DAX feature in ext4/xfs uses the persistent inode
> attribute, i.e. FS_DAX_FL/FS_XFLAG_DAX, to indicate if DAX shall be
> enable for this file or not when filesystem is mounted in per-file DAX
> mode.
>
> To keep compatible with this feature in ext4/xfs, virtiofs also supports
> enabling DAX depending on the persistent inode attribute, which may be
> set/cleared by users inside guest or admin on host.
>
> This policy is used when '-o dax=attr' option is specified for
> virtiofsd.
I guess keep this patch higher up in the patch series as we want to make
sure this behavior works first. And then implement server specific policy.
Just a minor nit.
Once you post new patch series with kernel changes, I will spend some time
testing these patches.
Vivek
>
> Signed-off-by: Jeffle Xu <jefflexu at linux.alibaba.com>
> ---
> tools/virtiofsd/passthrough_ll.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
> index a5a5061906..6f75cd6d92 100644
> --- a/tools/virtiofsd/passthrough_ll.c
> +++ b/tools/virtiofsd/passthrough_ll.c
> @@ -1000,7 +1000,7 @@ static int do_statx(struct lo_data *lo, int dirfd, const char *pathname,
> return 0;
> }
>
> -static bool lo_should_enable_dax(struct lo_data *lo,
> +static bool lo_should_enable_dax(struct lo_data *lo, struct lo_inode *inode,
> struct fuse_entry_param *e)
> {
> if (lo->dax == DAX_NONE || !S_ISREG(e->attr.st_mode)) {
> @@ -1011,6 +1011,24 @@ static bool lo_should_enable_dax(struct lo_data *lo,
> return e->attr.st_size > FUSE_PERFILE_DAX_POINT;
> }
>
> + if (lo->dax & DAX_ATTR) {
> + int res, fd;
> + int ret = false;;
> + unsigned int attr;
> +
> + fd = lo_inode_open(lo, inode, O_RDONLY);
> + if (fd == -1) {
> + return false;
> + }
> +
> + res = ioctl(fd, FS_IOC_GETFLAGS, &attr);
> + if (!res && (attr & FS_DAX_FL))
> + ret = true;
> +
> + close(fd);
> + return ret;
> + }
> +
> return false;
> }
>
> @@ -1104,7 +1122,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
> }
> e->ino = inode->fuse_ino;
>
> - if (lo_should_enable_dax(lo, e)) {
> + if (lo_should_enable_dax(lo, inode, e)) {
> e->attr_flags |= FUSE_ATTR_DAX;
> }
>
> --
> 2.27.0
>
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