Jeffle Xu
2021-Aug-17 02:23 UTC
[virtiofsd PATCH v4 4/4] virtiofsd: support per-file DAX in FUSE_LOOKUP
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 at 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;
+
+ 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;
+ }
+
+ 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
Dr. David Alan Gilbert
2021-Aug-17 19:00 UTC
[Virtio-fs] [virtiofsd PATCH v4 4/4] virtiofsd: support per-file DAX in FUSE_LOOKUP
* Jeffle Xu (jefflexu at 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 at 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 at redhat.com > https://listman.redhat.com/mailman/listinfo/virtio-fs >-- Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK