| Message ID | 20210426152135.842037-3-groug@kaod.org |
|---|---|
| State | New |
| Headers | show |
| Series | virtiofsd: Add support for FUSE_SYNCFS request | expand |
On Mon, Apr 26, 2021 at 05:21:35PM +0200, Greg Kurz wrote: > Honor the expected behavior of syncfs() to synchronously flush all > data and metadata on linux systems. > > Flushing is done with syncfs(). This is suboptimal as it will also > flush writes performed by any other process on the same file system, > and thus add an unbounded time penalty to syncfs(). This may be > optimized in the future, but enforce correctness first. > > Signed-off-by: Greg Kurz <groug@kaod.org> > --- > tools/virtiofsd/fuse_lowlevel.c | 19 ++++++++++++++++++ > tools/virtiofsd/fuse_lowlevel.h | 13 ++++++++++++ > tools/virtiofsd/passthrough_ll.c | 29 +++++++++++++++++++++++++++ > tools/virtiofsd/passthrough_seccomp.c | 1 + > 4 files changed, 62 insertions(+) > > diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c > index 58e32fc96369..918ab11f54c2 100644 > --- a/tools/virtiofsd/fuse_lowlevel.c > +++ b/tools/virtiofsd/fuse_lowlevel.c > @@ -1870,6 +1870,24 @@ 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) > +{ > + struct fuse_syncfs_in *arg; > + > + arg = fuse_mbuf_iter_advance(iter, sizeof(*arg)); > + if (!arg) { > + fuse_reply_err(req, EINVAL); > + return; > + } > + > + if (req->se->op.syncfs) { > + req->se->op.syncfs(req, arg->flags); > + } else { > + fuse_reply_err(req, ENOSYS); > + } > +} > + > static void do_init(fuse_req_t req, fuse_ino_t nodeid, > struct fuse_mbuf_iter *iter) > { > @@ -2267,6 +2285,7 @@ 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 3bf786b03485..220bb3db4898 100644 > --- a/tools/virtiofsd/fuse_lowlevel.h > +++ b/tools/virtiofsd/fuse_lowlevel.h > @@ -1225,6 +1225,19 @@ 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 flags not used yet > + */ > + void (*syncfs)(fuse_req_t req, uint64_t flags); > }; > > /** > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 1553d2ef454f..6790a2f6fe10 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -3124,6 +3124,34 @@ static void lo_lseek(fuse_req_t req, fuse_ino_t ino, off_t off, int whence, > } > } > > +static void lo_syncfs(fuse_req_t req, uint64_t flags) > +{ > + struct lo_data *lo = lo_data(req); > + int fd, ret; > + > + /* No flags supported yet */ > + if (flags) { > + fuse_reply_err(req, EINVAL); > + return; > + } > + > + fd = lo_inode_open(lo, &lo->root, O_RDONLY); > + if (fd < 0) { > + fuse_reply_err(req, errno); > + return; > + } > + > + /* > + * FIXME: this is suboptimal because it will also flush unrelated > + * writes not coming from the client. This can dramatically > + * increase the time spent in syncfs() if some process is > + * writing lots of data on the same filesystem as virtiofsd. > + */ > + ret = syncfs(fd); Hi Greg, As we discussed in the community call that this works only if there are no other filesystems mounted as submounts under exported directory. We proably need to find a way to call syncfs() on all the filesystems which are submounts of exported directory. Might not be easy at all. Just mentioning it here so that we have a note about the limitation of current patch. Vivek > + fuse_reply_err(req, ret < 0 ? errno : 0); > + close(fd); > +} > + > static void lo_destroy(void *userdata) > { > struct lo_data *lo = (struct lo_data *)userdata; > @@ -3184,6 +3212,7 @@ 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 62441cfcdb95..343188447901 100644 > --- a/tools/virtiofsd/passthrough_seccomp.c > +++ b/tools/virtiofsd/passthrough_seccomp.c > @@ -107,6 +107,7 @@ 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), > -- > 2.26.3 >
On Wed, 5 May 2021 14:52:42 -0400 Vivek Goyal <vgoyal@redhat.com> wrote: > On Mon, Apr 26, 2021 at 05:21:35PM +0200, Greg Kurz wrote: > > Honor the expected behavior of syncfs() to synchronously flush all > > data and metadata on linux systems. > > > > Flushing is done with syncfs(). This is suboptimal as it will also > > flush writes performed by any other process on the same file system, > > and thus add an unbounded time penalty to syncfs(). This may be > > optimized in the future, but enforce correctness first. > > > > Signed-off-by: Greg Kurz <groug@kaod.org> > > --- > > tools/virtiofsd/fuse_lowlevel.c | 19 ++++++++++++++++++ > > tools/virtiofsd/fuse_lowlevel.h | 13 ++++++++++++ > > tools/virtiofsd/passthrough_ll.c | 29 +++++++++++++++++++++++++++ > > tools/virtiofsd/passthrough_seccomp.c | 1 + > > 4 files changed, 62 insertions(+) > > > > diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c > > index 58e32fc96369..918ab11f54c2 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.c > > +++ b/tools/virtiofsd/fuse_lowlevel.c > > @@ -1870,6 +1870,24 @@ 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) > > +{ > > + struct fuse_syncfs_in *arg; > > + > > + arg = fuse_mbuf_iter_advance(iter, sizeof(*arg)); > > + if (!arg) { > > + fuse_reply_err(req, EINVAL); > > + return; > > + } > > + > > + if (req->se->op.syncfs) { > > + req->se->op.syncfs(req, arg->flags); > > + } else { > > + fuse_reply_err(req, ENOSYS); > > + } > > +} > > + > > static void do_init(fuse_req_t req, fuse_ino_t nodeid, > > struct fuse_mbuf_iter *iter) > > { > > @@ -2267,6 +2285,7 @@ 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 3bf786b03485..220bb3db4898 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.h > > +++ b/tools/virtiofsd/fuse_lowlevel.h > > @@ -1225,6 +1225,19 @@ 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 flags not used yet > > + */ > > + void (*syncfs)(fuse_req_t req, uint64_t flags); > > }; > > > > /** > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 1553d2ef454f..6790a2f6fe10 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -3124,6 +3124,34 @@ static void lo_lseek(fuse_req_t req, fuse_ino_t ino, off_t off, int whence, > > } > > } > > > > +static void lo_syncfs(fuse_req_t req, uint64_t flags) > > +{ > > + struct lo_data *lo = lo_data(req); > > + int fd, ret; > > + > > + /* No flags supported yet */ > > + if (flags) { > > + fuse_reply_err(req, EINVAL); > > + return; > > + } > > + > > + fd = lo_inode_open(lo, &lo->root, O_RDONLY); > > + if (fd < 0) { > > + fuse_reply_err(req, errno); > > + return; > > + } > > + > > + /* > > + * FIXME: this is suboptimal because it will also flush unrelated > > + * writes not coming from the client. This can dramatically > > + * increase the time spent in syncfs() if some process is > > + * writing lots of data on the same filesystem as virtiofsd. > > + */ > > + ret = syncfs(fd); > > Hi Greg, > Hi Vivek, > As we discussed in the community call that this works only if there are > no other filesystems mounted as submounts under exported directory. > > We proably need to find a way to call syncfs() on all the filesystems > which are submounts of exported directory. Might not be easy at all. > I must confess I didn't investigate this case. I'll start looking. > Just mentioning it here so that we have a note about the limitation of > current patch. > Sure. I'll add a note for that. > Vivek > > > + fuse_reply_err(req, ret < 0 ? errno : 0); > > + close(fd); > > +} > > + > > static void lo_destroy(void *userdata) > > { > > struct lo_data *lo = (struct lo_data *)userdata; > > @@ -3184,6 +3212,7 @@ 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 62441cfcdb95..343188447901 100644 > > --- a/tools/virtiofsd/passthrough_seccomp.c > > +++ b/tools/virtiofsd/passthrough_seccomp.c > > @@ -107,6 +107,7 @@ 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), > > -- > > 2.26.3 > > >
diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c index 58e32fc96369..918ab11f54c2 100644 --- a/tools/virtiofsd/fuse_lowlevel.c +++ b/tools/virtiofsd/fuse_lowlevel.c @@ -1870,6 +1870,24 @@ 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) +{ + struct fuse_syncfs_in *arg; + + arg = fuse_mbuf_iter_advance(iter, sizeof(*arg)); + if (!arg) { + fuse_reply_err(req, EINVAL); + return; + } + + if (req->se->op.syncfs) { + req->se->op.syncfs(req, arg->flags); + } else { + fuse_reply_err(req, ENOSYS); + } +} + static void do_init(fuse_req_t req, fuse_ino_t nodeid, struct fuse_mbuf_iter *iter) { @@ -2267,6 +2285,7 @@ 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 3bf786b03485..220bb3db4898 100644 --- a/tools/virtiofsd/fuse_lowlevel.h +++ b/tools/virtiofsd/fuse_lowlevel.h @@ -1225,6 +1225,19 @@ 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 flags not used yet + */ + void (*syncfs)(fuse_req_t req, uint64_t flags); }; /** diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 1553d2ef454f..6790a2f6fe10 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -3124,6 +3124,34 @@ static void lo_lseek(fuse_req_t req, fuse_ino_t ino, off_t off, int whence, } } +static void lo_syncfs(fuse_req_t req, uint64_t flags) +{ + struct lo_data *lo = lo_data(req); + int fd, ret; + + /* No flags supported yet */ + if (flags) { + fuse_reply_err(req, EINVAL); + return; + } + + fd = lo_inode_open(lo, &lo->root, O_RDONLY); + if (fd < 0) { + fuse_reply_err(req, errno); + return; + } + + /* + * FIXME: this is suboptimal because it will also flush unrelated + * writes not coming from the client. This can dramatically + * increase the time spent in syncfs() if some process is + * writing lots of data on the same filesystem as virtiofsd. + */ + ret = syncfs(fd); + fuse_reply_err(req, ret < 0 ? errno : 0); + close(fd); +} + static void lo_destroy(void *userdata) { struct lo_data *lo = (struct lo_data *)userdata; @@ -3184,6 +3212,7 @@ 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 62441cfcdb95..343188447901 100644 --- a/tools/virtiofsd/passthrough_seccomp.c +++ b/tools/virtiofsd/passthrough_seccomp.c @@ -107,6 +107,7 @@ 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),
Honor the expected behavior of syncfs() to synchronously flush all data and metadata on linux systems. Flushing is done with syncfs(). This is suboptimal as it will also flush writes performed by any other process on the same file system, and thus add an unbounded time penalty to syncfs(). This may be optimized in the future, but enforce correctness first. Signed-off-by: Greg Kurz <groug@kaod.org> --- tools/virtiofsd/fuse_lowlevel.c | 19 ++++++++++++++++++ tools/virtiofsd/fuse_lowlevel.h | 13 ++++++++++++ tools/virtiofsd/passthrough_ll.c | 29 +++++++++++++++++++++++++++ tools/virtiofsd/passthrough_seccomp.c | 1 + 4 files changed, 62 insertions(+)