On Mon, 14 Feb 2022 16:43:15 +0100 German Maglione <gmagli...@redhat.com> wrote:
> On Mon, Feb 14, 2022 at 3:00 PM Greg Kurz <gr...@kaod.org> wrote: > > > Honor the expected behavior of syncfs() to synchronously flush all data > > and metadata to disk on linux systems. > > > > If virtiofsd is started with '-o announce_submounts', the client is > > expected to send a FUSE_SYNCFS request for each individual submount. > > In this case, we just create a new file descriptor on the submount > > inode with lo_inode_open(), call syncfs() on it and close it. The > > intermediary file is needed because O_PATH descriptors aren't > > backed by an actual file and syncfs() would fail with EBADF. > > > > If virtiofsd is started without '-o announce_submounts' or if the > > client doesn't have the FUSE_CAP_SUBMOUNTS capability, the client > > only sends a single FUSE_SYNCFS request for the root inode. The > > server would thus need to track submounts internally and call > > syncfs() on each of them. This will be implemented later. > > > > Note that syncfs() might suffer from a time penalty if the submounts > > are being hammered by some unrelated workload on the host. The only > > solution to prevent that is to avoid shared mounts. > > > > Signed-off-by: Greg Kurz <gr...@kaod.org> > > --- > > tools/virtiofsd/fuse_lowlevel.c | 11 +++++++ > > tools/virtiofsd/fuse_lowlevel.h | 13 ++++++++ > > tools/virtiofsd/passthrough_ll.c | 45 +++++++++++++++++++++++++++ > > tools/virtiofsd/passthrough_seccomp.c | 1 + > > 4 files changed, 70 insertions(+) > > > > diff --git a/tools/virtiofsd/fuse_lowlevel.c > > b/tools/virtiofsd/fuse_lowlevel.c > > index e4679c73abc2..e02d8b25a5f6 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.c > > +++ b/tools/virtiofsd/fuse_lowlevel.c > > @@ -1876,6 +1876,16 @@ static void do_lseek(fuse_req_t req, fuse_ino_t > > nodeid, > > } > > } > > > > +static void do_syncfs(fuse_req_t req, fuse_ino_t nodeid, > > + struct fuse_mbuf_iter *iter) > > +{ > > + if (req->se->op.syncfs) { > > + req->se->op.syncfs(req, nodeid); > > + } else { > > + fuse_reply_err(req, ENOSYS); > > + } > > +} > > + > > static void do_init(fuse_req_t req, fuse_ino_t nodeid, > > struct fuse_mbuf_iter *iter) > > { > > @@ -2280,6 +2290,7 @@ static struct { > > [FUSE_RENAME2] = { do_rename2, "RENAME2" }, > > [FUSE_COPY_FILE_RANGE] = { do_copy_file_range, "COPY_FILE_RANGE" }, > > [FUSE_LSEEK] = { do_lseek, "LSEEK" }, > > + [FUSE_SYNCFS] = { do_syncfs, "SYNCFS" }, > > }; > > > > #define FUSE_MAXOP (sizeof(fuse_ll_ops) / sizeof(fuse_ll_ops[0])) > > diff --git a/tools/virtiofsd/fuse_lowlevel.h > > b/tools/virtiofsd/fuse_lowlevel.h > > index c55c0ca2fc1c..b889dae4de0e 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.h > > +++ b/tools/virtiofsd/fuse_lowlevel.h > > @@ -1226,6 +1226,19 @@ struct fuse_lowlevel_ops { > > */ > > void (*lseek)(fuse_req_t req, fuse_ino_t ino, off_t off, int whence, > > struct fuse_file_info *fi); > > + > > + /** > > + * Synchronize file system content > > + * > > + * If this request is answered with an error code of ENOSYS, > > + * this is treated as success and future calls to syncfs() will > > + * succeed automatically without being sent to the filesystem > > + * process. > > + * > > + * @param req request handle > > + * @param ino the inode number > > + */ > > + void (*syncfs)(fuse_req_t req, fuse_ino_t ino); > > }; > > > > /** > > diff --git a/tools/virtiofsd/passthrough_ll.c > > b/tools/virtiofsd/passthrough_ll.c > > index b3d0674f6d2f..2bf5d40df531 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -3357,6 +3357,50 @@ static void lo_lseek(fuse_req_t req, fuse_ino_t > > ino, off_t off, int whence, > > } > > } > > > > +static int lo_do_syncfs(struct lo_data *lo, struct lo_inode *inode) > > +{ > > + int fd, ret = 0; > > + > > + fuse_log(FUSE_LOG_DEBUG, "lo_do_syncfs(ino=%" PRIu64 ")\n", > > + inode->fuse_ino); > > + > > + fd = lo_inode_open(lo, inode, O_RDONLY); > > + if (fd < 0) { > > + return -fd; > > + } > > + > > + if (syncfs(fd) < 0) { > > + ret = errno; > > + } > > + > > + close(fd); > > + return ret; > > +} > > + > > +static void lo_syncfs(fuse_req_t req, fuse_ino_t ino) > > +{ > > + struct lo_data *lo = lo_data(req); > > + int err; > > + > > + if (lo->announce_submounts) { > > + struct lo_inode *inode; > > + > > + inode = lo_inode(req, ino); > > + if (!inode) { > > + fuse_reply_err(req, EBADF); > > + return; > > + } > > + > > + err = lo_do_syncfs(lo, inode); > > + lo_inode_put(lo, &inode); > > + } else { > > + /* Requires the sever to track submounts. Not implemented yet */ > > + err = ENOSYS; > > + } > > > > In the current rust version we don't check if announce_submount is enabled, > with and without it lo_syncfs do the same thing. So, if announce_submount > is not enabled, at least the root shared dir get synced. > I hesitated to do that but since the announce_submount case is handled in patch 3, I kept it simple. Anyway, I'm fine to post a new version that matches what the rust implementation does. > > > > + > > + fuse_reply_err(req, err); > > +} > > + > > static void lo_destroy(void *userdata) > > { > > struct lo_data *lo = (struct lo_data *)userdata; > > @@ -3417,6 +3461,7 @@ static struct fuse_lowlevel_ops lo_oper = { > > .copy_file_range = lo_copy_file_range, > > #endif > > .lseek = lo_lseek, > > + .syncfs = lo_syncfs, > > .destroy = lo_destroy, > > }; > > > > diff --git a/tools/virtiofsd/passthrough_seccomp.c > > b/tools/virtiofsd/passthrough_seccomp.c > > index a3ce9f898d2d..3e9d6181dc69 100644 > > --- a/tools/virtiofsd/passthrough_seccomp.c > > +++ b/tools/virtiofsd/passthrough_seccomp.c > > @@ -108,6 +108,7 @@ static const int syscall_allowlist[] = { > > SCMP_SYS(set_robust_list), > > SCMP_SYS(setxattr), > > SCMP_SYS(symlinkat), > > + SCMP_SYS(syncfs), > > SCMP_SYS(time), /* Rarely needed, except on static builds */ > > SCMP_SYS(tgkill), > > SCMP_SYS(unlinkat), > > -- > > 2.34.1 > > > > _______________________________________________ > > Virtio-fs mailing list > > Virtio-fs@redhat.com > > https://listman.redhat.com/mailman/listinfo/virtio-fs > > > > > _______________________________________________ Virtio-fs mailing list Virtio-fs@redhat.com https://listman.redhat.com/mailman/listinfo/virtio-fs