From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Jeffle Xu <jefflexu@linux.alibaba.com>
Cc: vgoyal@redhat.com, stefanha@redhat.com, miklos@szeredi.hu,
linux-fsdevel@vger.kernel.org, virtio-fs@redhat.com,
joseph.qi@linux.alibaba.com,
virtualization@lists.linux-foundation.org
Subject: Re: [Virtio-fs] [virtiofsd PATCH v4 4/4] virtiofsd: support per-file DAX in FUSE_LOOKUP
Date: Tue, 17 Aug 2021 20:00:22 +0100 [thread overview]
Message-ID: <YRwHRmL/jUSqgkIU@work-vm> (raw)
In-Reply-To: <20210817022347.18098-5-jefflexu@linux.alibaba.com>
* Jeffle Xu (jefflexu@linux.alibaba.com) wrote:
> For passthrough, when the corresponding virtiofs in guest is mounted
> with '-o dax=inode', advertise that the file is capable of per-file
> DAX if the inode in the backend fs is marked with FS_DAX_FL flag.
>
> Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
> ---
> tools/virtiofsd/passthrough_ll.c | 43 ++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
> index 5b6228210f..4cbd904248 100644
> --- a/tools/virtiofsd/passthrough_ll.c
> +++ b/tools/virtiofsd/passthrough_ll.c
> @@ -171,6 +171,7 @@ struct lo_data {
> int allow_direct_io;
> int announce_submounts;
> int perfile_dax_cap; /* capability of backend fs */
> + bool perfile_dax; /* enable per-file DAX or not */
> bool use_statx;
> struct lo_inode root;
> GHashTable *inodes; /* protected by lo->mutex */
> @@ -716,6 +717,10 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn)
>
> if (conn->capable & FUSE_CAP_PERFILE_DAX && lo->perfile_dax_cap ) {
> conn->want |= FUSE_CAP_PERFILE_DAX;
> + lo->perfile_dax = 1;
> + }
> + else {
> + lo->perfile_dax = 0;
> }
> }
>
> @@ -983,6 +988,41 @@ static int do_statx(struct lo_data *lo, int dirfd, const char *pathname,
> return 0;
> }
>
> +/*
> + * If the file is marked with FS_DAX_FL or FS_XFLAG_DAX, then DAX should be
> + * enabled for this file.
> + */
> +static bool lo_should_enable_dax(struct lo_data *lo, struct lo_inode *dir,
> + const char *name)
> +{
> + int res, fd;
> + int ret = false;;
> + unsigned int attr;
> + struct fsxattr xattr;
> +
> + if (!lo->perfile_dax)
> + return false;
> +
> + /* Open file without O_PATH, so that ioctl can be called. */
> + fd = openat(dir->fd, name, O_NOFOLLOW);
> + if (fd == -1)
> + return false;
Doesn't that defeat the whole benefit of using O_PATH - i.e. that we
might stumble into a /dev node or something else we're not allowed to
open?
> + if (lo->perfile_dax_cap == DAX_CAP_FLAGS) {
> + res = ioctl(fd, FS_IOC_GETFLAGS, &attr);
> + if (!res && (attr & FS_DAX_FL))
> + ret = true;
> + }
> + else if (lo->perfile_dax_cap == DAX_CAP_XATTR) {
> + res = ioctl(fd, FS_IOC_FSGETXATTR, &xattr);
> + if (!res && (xattr.fsx_xflags & FS_XFLAG_DAX))
> + ret = true;
> + }
This all looks pretty expensive for each lookup.
Dave
> + close(fd);
> + return ret;
> +}
> +
> /*
> * Increments nlookup on the inode on success. unref_inode_lolocked() must be
> * called eventually to decrement nlookup again. If inodep is non-NULL, the
> @@ -1038,6 +1078,9 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
> e->attr_flags |= FUSE_ATTR_SUBMOUNT;
> }
>
> + if (lo_should_enable_dax(lo, dir, name))
> + e->attr_flags |= FUSE_ATTR_DAX;
> +
> inode = lo_find(lo, &e->attr, mnt_id);
> if (inode) {
> close(newfd);
> --
> 2.27.0
>
> _______________________________________________
> Virtio-fs mailing list
> Virtio-fs@redhat.com
> https://listman.redhat.com/mailman/listinfo/virtio-fs
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2021-08-17 19:00 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-17 2:22 [PATCH v4 0/8] fuse,virtiofs: support per-file DAX Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 1/8] fuse: add fuse_should_enable_dax() helper Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 2/8] fuse: Make DAX mount option a tri-state Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 3/8] fuse: support per-file DAX Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 4/8] fuse: negotiate if server/client supports " Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 5/8] fuse: enable " Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 6/8] fuse: mark inode DONT_CACHE when per-file DAX indication changes Jeffle Xu
2021-08-17 10:26 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-08-17 13:23 ` JeffleXu
2021-08-17 2:22 ` [PATCH v4 7/8] fuse: support changing per-file DAX flag inside guest Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 8/8] fuse: show '-o dax=inode' option only when FUSE server supports Jeffle Xu
2021-08-17 2:23 ` [virtiofsd PATCH v4 0/4] virtiofsd: support per-file DAX Jeffle Xu
2021-08-17 2:23 ` [virtiofsd PATCH v4 1/4] virtiofsd: add .ioctl() support Jeffle Xu
2021-08-18 17:33 ` Vivek Goyal
2021-08-17 2:23 ` [virtiofsd PATCH v4 2/4] virtiofsd: expand fuse protocol to support per-file DAX Jeffle Xu
2021-08-17 2:23 ` [virtiofsd PATCH v4 3/4] virtiofsd: support per-file DAX negotiation in FUSE_INIT Jeffle Xu
2021-08-17 17:15 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-08-18 5:28 ` JeffleXu
2021-08-19 13:57 ` Dr. David Alan Gilbert
2021-08-18 17:30 ` Vivek Goyal
2021-08-17 2:23 ` [virtiofsd PATCH v4 4/4] virtiofsd: support per-file DAX in FUSE_LOOKUP Jeffle Xu
2021-08-17 19:00 ` Dr. David Alan Gilbert [this message]
2021-08-18 5:46 ` [Virtio-fs] " JeffleXu
2021-08-19 13:08 ` Dr. David Alan Gilbert
2021-08-20 5:03 ` JeffleXu
2021-08-24 10:15 ` Greg Kurz
2021-09-08 10:34 ` JeffleXu
2021-08-17 8:06 ` [PATCH v4 0/8] fuse,virtiofs: support per-file DAX Miklos Szeredi
2021-08-17 9:32 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-08-17 10:09 ` Miklos Szeredi
2021-08-17 10:37 ` Dr. David Alan Gilbert
2021-08-17 13:08 ` JeffleXu
2021-08-17 14:11 ` Miklos Szeredi
2021-08-17 15:19 ` Vivek Goyal
2021-08-17 14:54 ` Vivek Goyal
2021-08-18 5:10 ` JeffleXu
2021-08-19 6:14 ` JeffleXu
2021-08-17 12:40 ` Vivek Goyal
2021-09-16 8:21 ` JeffleXu
2021-09-18 3:06 ` JeffleXu
2021-09-19 19:45 ` Vivek Goyal
2021-09-22 8:16 ` JeffleXu
2021-08-17 12:39 ` Vivek Goyal
2021-08-17 13:22 ` JeffleXu
2021-08-17 14:08 ` Miklos Szeredi
2021-08-18 3:39 ` JeffleXu
2021-08-18 5:08 ` Miklos Szeredi
2021-08-18 16:58 ` Vivek Goyal
2021-09-03 5:30 ` JeffleXu
2021-09-07 14:51 ` Miklos Szeredi
2021-08-17 14:57 ` Vivek Goyal
2021-08-18 5:20 ` JeffleXu
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