| Message ID | 20191212163904.159893-38-dgilbert@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtiofs daemon [all] | expand |
On Thu, Dec 12, 2019 at 04:37:57PM +0000, Dr. David Alan Gilbert (git) wrote: > From: Miklos Szeredi <mszeredi@redhat.com> > > We have two operations that cannot be done race-free on a symlink in > certain cases: utimes and link. > > Add racy fallback for these if the race-free method doesn't work. We do > our best to avoid races even in this case: > > - get absolute path by reading /proc/self/fd/NN symlink > > - lookup parent directory: after this we are safe against renames in > ancestors > > - lookup name in parent directory, and verify that we got to the original > inode, if not retry the whole thing > > Both utimes(2) and link(2) hold i_lock on the inode across the operation, > so a racing rename/delete by this fuse instance is not possible, only from > other entities changing the filesystem. > > If the "norace" option is given, then disable the racy fallbacks. > > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> > --- > tools/virtiofsd/passthrough_ll.c | 159 +++++++++++++++++++++++++++---- > 1 file changed, 142 insertions(+), 17 deletions(-) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 93e74cce21..1faae2753f 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -98,6 +98,7 @@ enum { > struct lo_data { > pthread_mutex_t mutex; > int debug; > + int norace; > int writeback; > int flock; > int xattr; > @@ -124,10 +125,15 @@ static const struct fuse_opt lo_opts[] = { > { "cache=never", offsetof(struct lo_data, cache), CACHE_NEVER }, > { "cache=auto", offsetof(struct lo_data, cache), CACHE_NORMAL }, > { "cache=always", offsetof(struct lo_data, cache), CACHE_ALWAYS }, > - > + { "norace", offsetof(struct lo_data, norace), 1 }, > FUSE_OPT_END > }; > > +static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n); > + > +static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st); > + > + > static struct lo_data *lo_data(fuse_req_t req) > { > return (struct lo_data *)fuse_req_userdata(req); > @@ -347,23 +353,127 @@ static void lo_getattr(fuse_req_t req, fuse_ino_t ino, > fuse_reply_attr(req, &buf, lo->timeout); > } > > -static int utimensat_empty_nofollow(struct lo_inode *inode, > - const struct timespec *tv) > +static int lo_parent_and_name(struct lo_data *lo, struct lo_inode *inode, > + char path[PATH_MAX], struct lo_inode **parent) > { > - int res; > char procname[64]; > + char *last; > + struct stat stat; > + struct lo_inode *p; > + int retries = 2; > + int res; > + > +retry: > + sprintf(procname, "/proc/self/fd/%i", inode->fd); > + > + res = readlink(procname, path, PATH_MAX); > + if (res < 0) { > + fuse_log(FUSE_LOG_WARNING, "lo_parent_and_name: readlink failed: %m\n"); I think it's better to use __func__ macro in case the function name is changed in the future. fuse_log(FUSE_LOG_WARNING, "%s: readlink failed: %m\n", __func__); > + goto fail_noretry; > + } > + > + if (res >= PATH_MAX) { > + fuse_log(FUSE_LOG_WARNING, "lo_parent_and_name: readlink overflowed\n"); fuse_log(FUSE_LOG_WARNING, "%s: readlink overflowed\n", __func__); > + goto fail_noretry; > + } > + path[res] = '\0'; > + > + last = strrchr(path, '/'); > + if (last == NULL) { > + /* Shouldn't happen */ > + fuse_log( > + FUSE_LOG_WARNING, > + "lo_parent_and_name: INTERNAL ERROR: bad path read from proc\n"); fuse_log( FUSE_LOG_WARNING, "%s: INTERNAL ERROR: bad path read from proc\n", __func__); > + goto fail_noretry; > + } > + if (last == path) { > + p = &lo->root; > + pthread_mutex_lock(&lo->mutex); > + p->refcount++; > + pthread_mutex_unlock(&lo->mutex); > + } else { > + *last = '\0'; > + res = fstatat(AT_FDCWD, last == path ? "/" : path, &stat, 0); > + if (res == -1) { > + if (!retries) { > + fuse_log(FUSE_LOG_WARNING, > + "lo_parent_and_name: failed to stat parent: %m\n"); fuse_log(FUSE_LOG_WARNING, "%s: failed to stat parent: %m\n", __func__); > + } > + goto fail; > + } > + p = lo_find(lo, &stat); > + if (p == NULL) { > + if (!retries) { > + fuse_log(FUSE_LOG_WARNING, > + "lo_parent_and_name: failed to find parent\n"); fuse_log(FUSE_LOG_WARNING, "%s: failed to find parent\n", __func__); > + } > + goto fail; > + } > + } > + last++; > + res = fstatat(p->fd, last, &stat, AT_SYMLINK_NOFOLLOW); > + if (res == -1) { > + if (!retries) { > + fuse_log(FUSE_LOG_WARNING, > + "lo_parent_and_name: failed to stat last\n"); fuse_log(FUSE_LOG_WARNING, "%s: failed to stat last\n", __func__); > + } > + goto fail_unref; > + } > + if (stat.st_dev != inode->dev || stat.st_ino != inode->ino) { > + if (!retries) { > + fuse_log(FUSE_LOG_WARNING, > + "lo_parent_and_name: failed to match last\n"); fuse_log(FUSE_LOG_WARNING, "%s: failed to match last\n", __func__); > + } > + goto fail_unref; > + } > + *parent = p; > + memmove(path, last, strlen(last) + 1); > + > + return 0; > + > +fail_unref: > + unref_inode(lo, p, 1); > +fail: > + if (retries) { > + retries--; > + goto retry; > + } > +fail_noretry: > + errno = EIO; > + return -1; > +} > + > +static int utimensat_empty(struct lo_data *lo, struct lo_inode *inode, > + const struct timespec *tv) > +{ > + int res; > + struct lo_inode *parent; > + char path[PATH_MAX]; > > if (inode->is_symlink) { > - res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); > + res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH); > if (res == -1 && errno == EINVAL) { > /* Sorry, no race free way to set times on symlink. */ > - errno = EPERM; > + if (lo->norace) { > + errno = EPERM; > + } else { > + goto fallback; > + } > } > return res; > } > - sprintf(procname, "/proc/self/fd/%i", inode->fd); > + sprintf(path, "/proc/self/fd/%i", inode->fd); > + > + return utimensat(AT_FDCWD, path, tv, 0); > > - return utimensat(AT_FDCWD, procname, tv, 0); > +fallback: > + res = lo_parent_and_name(lo, inode, path, &parent); > + if (res != -1) { > + res = utimensat(parent->fd, path, tv, AT_SYMLINK_NOFOLLOW); > + unref_inode(lo, parent, 1); > + } > + > + return res; > } > > static int lo_fi_fd(fuse_req_t req, struct fuse_file_info *fi) > @@ -387,6 +497,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > { > int saverr; > char procname[64]; > + struct lo_data *lo = lo_data(req); > struct lo_inode *inode; > int ifd; > int res; > @@ -459,7 +570,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > if (fi) { > res = futimens(fd, tv); > } else { > - res = utimensat_empty_nofollow(inode, tv); > + res = utimensat_empty(lo, inode, tv); > } > if (res == -1) { > goto out_err; > @@ -692,24 +803,38 @@ static void lo_symlink(fuse_req_t req, const char *link, fuse_ino_t parent, > lo_mknod_symlink(req, parent, name, S_IFLNK, 0, link); > } > > -static int linkat_empty_nofollow(struct lo_inode *inode, int dfd, > - const char *name) > +static int linkat_empty_nofollow(struct lo_data *lo, struct lo_inode *inode, > + int dfd, const char *name) > { > int res; > - char procname[64]; > + struct lo_inode *parent; > + char path[PATH_MAX]; > > if (inode->is_symlink) { > res = linkat(inode->fd, "", dfd, name, AT_EMPTY_PATH); > if (res == -1 && (errno == ENOENT || errno == EINVAL)) { > /* Sorry, no race free way to hard-link a symlink. */ > - errno = EPERM; > + if (lo->norace) { > + errno = EPERM; > + } else { > + goto fallback; > + } > } > return res; > } > > - sprintf(procname, "/proc/self/fd/%i", inode->fd); > + sprintf(path, "/proc/self/fd/%i", inode->fd); > + > + return linkat(AT_FDCWD, path, dfd, name, AT_SYMLINK_FOLLOW); > + > +fallback: > + res = lo_parent_and_name(lo, inode, path, &parent); > + if (res != -1) { > + res = linkat(parent->fd, path, dfd, name, 0); > + unref_inode(lo, parent, 1); > + } > > - return linkat(AT_FDCWD, procname, dfd, name, AT_SYMLINK_FOLLOW); > + return res; > } > > static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, > @@ -731,7 +856,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, > e.attr_timeout = lo->timeout; > e.entry_timeout = lo->timeout; > > - res = linkat_empty_nofollow(inode, lo_fd(req, parent), name); > + res = linkat_empty_nofollow(lo, inode, lo_fd(req, parent), name); > if (res == -1) { > goto out_err; > } > @@ -1544,7 +1669,7 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name, > } > > if (inode->is_symlink) { > - /* Sorry, no race free way to setxattr on symlink. */ > + /* Sorry, no race free way to removexattr on symlink. */ > saverr = EPERM; > goto out; > } Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
* Masayoshi Mizuma (msys.mizuma@gmail.com) wrote: > On Thu, Dec 12, 2019 at 04:37:57PM +0000, Dr. David Alan Gilbert (git) wrote: > > From: Miklos Szeredi <mszeredi@redhat.com> > > > > We have two operations that cannot be done race-free on a symlink in > > certain cases: utimes and link. > > > > Add racy fallback for these if the race-free method doesn't work. We do > > our best to avoid races even in this case: > > > > - get absolute path by reading /proc/self/fd/NN symlink > > > > - lookup parent directory: after this we are safe against renames in > > ancestors > > > > - lookup name in parent directory, and verify that we got to the original > > inode, if not retry the whole thing > > > > Both utimes(2) and link(2) hold i_lock on the inode across the operation, > > so a racing rename/delete by this fuse instance is not possible, only from > > other entities changing the filesystem. > > > > If the "norace" option is given, then disable the racy fallbacks. > > > > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> > > --- > > tools/virtiofsd/passthrough_ll.c | 159 +++++++++++++++++++++++++++---- > > 1 file changed, 142 insertions(+), 17 deletions(-) > > > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 93e74cce21..1faae2753f 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -98,6 +98,7 @@ enum { > > struct lo_data { > > pthread_mutex_t mutex; > > int debug; > > + int norace; > > int writeback; > > int flock; > > int xattr; > > @@ -124,10 +125,15 @@ static const struct fuse_opt lo_opts[] = { > > { "cache=never", offsetof(struct lo_data, cache), CACHE_NEVER }, > > { "cache=auto", offsetof(struct lo_data, cache), CACHE_NORMAL }, > > { "cache=always", offsetof(struct lo_data, cache), CACHE_ALWAYS }, > > - > > + { "norace", offsetof(struct lo_data, norace), 1 }, > > FUSE_OPT_END > > }; > > > > +static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n); > > + > > +static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st); > > + > > + > > static struct lo_data *lo_data(fuse_req_t req) > > { > > return (struct lo_data *)fuse_req_userdata(req); > > @@ -347,23 +353,127 @@ static void lo_getattr(fuse_req_t req, fuse_ino_t ino, > > fuse_reply_attr(req, &buf, lo->timeout); > > } > > > -static int utimensat_empty_nofollow(struct lo_inode *inode, > > - const struct timespec *tv) > > +static int lo_parent_and_name(struct lo_data *lo, struct lo_inode *inode, > > + char path[PATH_MAX], struct lo_inode **parent) > > { > > - int res; > > char procname[64]; > > + char *last; > > + struct stat stat; > > + struct lo_inode *p; > > + int retries = 2; > > + int res; > > + > > +retry: > > + sprintf(procname, "/proc/self/fd/%i", inode->fd); > > + > > + res = readlink(procname, path, PATH_MAX); > > + if (res < 0) { > > > + fuse_log(FUSE_LOG_WARNING, "lo_parent_and_name: readlink failed: %m\n"); > > I think it's better to use __func__ macro in case the function name is > changed in the future. Yes, agreed - I've changed them all > fuse_log(FUSE_LOG_WARNING, "%s: readlink failed: %m\n", __func__); > > > + goto fail_noretry; > > + } > > + > > + if (res >= PATH_MAX) { > > > + fuse_log(FUSE_LOG_WARNING, "lo_parent_and_name: readlink overflowed\n"); > > fuse_log(FUSE_LOG_WARNING, "%s: readlink overflowed\n", __func__); > > > + goto fail_noretry; > > + } > > + path[res] = '\0'; > > + > > + last = strrchr(path, '/'); > > + if (last == NULL) { > > + /* Shouldn't happen */ > > > + fuse_log( > > + FUSE_LOG_WARNING, > > + "lo_parent_and_name: INTERNAL ERROR: bad path read from proc\n"); > > fuse_log( > FUSE_LOG_WARNING, > "%s: INTERNAL ERROR: bad path read from proc\n", __func__); > > > + goto fail_noretry; > > + } > > + if (last == path) { > > + p = &lo->root; > > + pthread_mutex_lock(&lo->mutex); > > + p->refcount++; > > + pthread_mutex_unlock(&lo->mutex); > > + } else { > > + *last = '\0'; > > + res = fstatat(AT_FDCWD, last == path ? "/" : path, &stat, 0); > > + if (res == -1) { > > + if (!retries) { > > > + fuse_log(FUSE_LOG_WARNING, > > + "lo_parent_and_name: failed to stat parent: %m\n"); > > fuse_log(FUSE_LOG_WARNING, > "%s: failed to stat parent: %m\n", __func__); > > > + } > > + goto fail; > > + } > > + p = lo_find(lo, &stat); > > + if (p == NULL) { > > + if (!retries) { > > > + fuse_log(FUSE_LOG_WARNING, > > + "lo_parent_and_name: failed to find parent\n"); > > fuse_log(FUSE_LOG_WARNING, > "%s: failed to find parent\n", __func__); > > > + } > > + goto fail; > > + } > > + } > > + last++; > > + res = fstatat(p->fd, last, &stat, AT_SYMLINK_NOFOLLOW); > > + if (res == -1) { > > + if (!retries) { > > > + fuse_log(FUSE_LOG_WARNING, > > + "lo_parent_and_name: failed to stat last\n"); > > fuse_log(FUSE_LOG_WARNING, > "%s: failed to stat last\n", __func__); > > > + } > > + goto fail_unref; > > + } > > + if (stat.st_dev != inode->dev || stat.st_ino != inode->ino) { > > + if (!retries) { > > > + fuse_log(FUSE_LOG_WARNING, > > + "lo_parent_and_name: failed to match last\n"); > > fuse_log(FUSE_LOG_WARNING, > "%s: failed to match last\n", __func__); > > > + } > > + goto fail_unref; > > + } > > + *parent = p; > > + memmove(path, last, strlen(last) + 1); > > + > > + return 0; > > + > > +fail_unref: > > + unref_inode(lo, p, 1); > > +fail: > > + if (retries) { > > + retries--; > > + goto retry; > > + } > > +fail_noretry: > > + errno = EIO; > > + return -1; > > +} > > + > > +static int utimensat_empty(struct lo_data *lo, struct lo_inode *inode, > > + const struct timespec *tv) > > +{ > > + int res; > > + struct lo_inode *parent; > > + char path[PATH_MAX]; > > > > if (inode->is_symlink) { > > - res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); > > + res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH); > > if (res == -1 && errno == EINVAL) { > > /* Sorry, no race free way to set times on symlink. */ > > - errno = EPERM; > > + if (lo->norace) { > > + errno = EPERM; > > + } else { > > + goto fallback; > > + } > > } > > return res; > > } > > - sprintf(procname, "/proc/self/fd/%i", inode->fd); > > + sprintf(path, "/proc/self/fd/%i", inode->fd); > > + > > + return utimensat(AT_FDCWD, path, tv, 0); > > > > - return utimensat(AT_FDCWD, procname, tv, 0); > > +fallback: > > + res = lo_parent_and_name(lo, inode, path, &parent); > > + if (res != -1) { > > + res = utimensat(parent->fd, path, tv, AT_SYMLINK_NOFOLLOW); > > + unref_inode(lo, parent, 1); > > + } > > + > > + return res; > > } > > > > static int lo_fi_fd(fuse_req_t req, struct fuse_file_info *fi) > > @@ -387,6 +497,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > > { > > int saverr; > > char procname[64]; > > + struct lo_data *lo = lo_data(req); > > struct lo_inode *inode; > > int ifd; > > int res; > > @@ -459,7 +570,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > > if (fi) { > > res = futimens(fd, tv); > > } else { > > - res = utimensat_empty_nofollow(inode, tv); > > + res = utimensat_empty(lo, inode, tv); > > } > > if (res == -1) { > > goto out_err; > > @@ -692,24 +803,38 @@ static void lo_symlink(fuse_req_t req, const char *link, fuse_ino_t parent, > > lo_mknod_symlink(req, parent, name, S_IFLNK, 0, link); > > } > > > > -static int linkat_empty_nofollow(struct lo_inode *inode, int dfd, > > - const char *name) > > +static int linkat_empty_nofollow(struct lo_data *lo, struct lo_inode *inode, > > + int dfd, const char *name) > > { > > int res; > > - char procname[64]; > > + struct lo_inode *parent; > > + char path[PATH_MAX]; > > > > if (inode->is_symlink) { > > res = linkat(inode->fd, "", dfd, name, AT_EMPTY_PATH); > > if (res == -1 && (errno == ENOENT || errno == EINVAL)) { > > /* Sorry, no race free way to hard-link a symlink. */ > > - errno = EPERM; > > + if (lo->norace) { > > + errno = EPERM; > > + } else { > > + goto fallback; > > + } > > } > > return res; > > } > > > > - sprintf(procname, "/proc/self/fd/%i", inode->fd); > > + sprintf(path, "/proc/self/fd/%i", inode->fd); > > + > > + return linkat(AT_FDCWD, path, dfd, name, AT_SYMLINK_FOLLOW); > > + > > +fallback: > > + res = lo_parent_and_name(lo, inode, path, &parent); > > + if (res != -1) { > > + res = linkat(parent->fd, path, dfd, name, 0); > > + unref_inode(lo, parent, 1); > > + } > > > > - return linkat(AT_FDCWD, procname, dfd, name, AT_SYMLINK_FOLLOW); > > + return res; > > } > > > > static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, > > @@ -731,7 +856,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, > > e.attr_timeout = lo->timeout; > > e.entry_timeout = lo->timeout; > > > > - res = linkat_empty_nofollow(inode, lo_fd(req, parent), name); > > + res = linkat_empty_nofollow(lo, inode, lo_fd(req, parent), name); > > if (res == -1) { > > goto out_err; > > } > > @@ -1544,7 +1669,7 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name, > > } > > > > if (inode->is_symlink) { > > - /* Sorry, no race free way to setxattr on symlink. */ > > + /* Sorry, no race free way to removexattr on symlink. */ I've undone that change; since it looks bogus. > > saverr = EPERM; > > goto out; > > } > > Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Thanks. -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 93e74cce21..1faae2753f 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -98,6 +98,7 @@ enum { struct lo_data { pthread_mutex_t mutex; int debug; + int norace; int writeback; int flock; int xattr; @@ -124,10 +125,15 @@ static const struct fuse_opt lo_opts[] = { { "cache=never", offsetof(struct lo_data, cache), CACHE_NEVER }, { "cache=auto", offsetof(struct lo_data, cache), CACHE_NORMAL }, { "cache=always", offsetof(struct lo_data, cache), CACHE_ALWAYS }, - + { "norace", offsetof(struct lo_data, norace), 1 }, FUSE_OPT_END }; +static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n); + +static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st); + + static struct lo_data *lo_data(fuse_req_t req) { return (struct lo_data *)fuse_req_userdata(req); @@ -347,23 +353,127 @@ static void lo_getattr(fuse_req_t req, fuse_ino_t ino, fuse_reply_attr(req, &buf, lo->timeout); } -static int utimensat_empty_nofollow(struct lo_inode *inode, - const struct timespec *tv) +static int lo_parent_and_name(struct lo_data *lo, struct lo_inode *inode, + char path[PATH_MAX], struct lo_inode **parent) { - int res; char procname[64]; + char *last; + struct stat stat; + struct lo_inode *p; + int retries = 2; + int res; + +retry: + sprintf(procname, "/proc/self/fd/%i", inode->fd); + + res = readlink(procname, path, PATH_MAX); + if (res < 0) { + fuse_log(FUSE_LOG_WARNING, "lo_parent_and_name: readlink failed: %m\n"); + goto fail_noretry; + } + + if (res >= PATH_MAX) { + fuse_log(FUSE_LOG_WARNING, "lo_parent_and_name: readlink overflowed\n"); + goto fail_noretry; + } + path[res] = '\0'; + + last = strrchr(path, '/'); + if (last == NULL) { + /* Shouldn't happen */ + fuse_log( + FUSE_LOG_WARNING, + "lo_parent_and_name: INTERNAL ERROR: bad path read from proc\n"); + goto fail_noretry; + } + if (last == path) { + p = &lo->root; + pthread_mutex_lock(&lo->mutex); + p->refcount++; + pthread_mutex_unlock(&lo->mutex); + } else { + *last = '\0'; + res = fstatat(AT_FDCWD, last == path ? "/" : path, &stat, 0); + if (res == -1) { + if (!retries) { + fuse_log(FUSE_LOG_WARNING, + "lo_parent_and_name: failed to stat parent: %m\n"); + } + goto fail; + } + p = lo_find(lo, &stat); + if (p == NULL) { + if (!retries) { + fuse_log(FUSE_LOG_WARNING, + "lo_parent_and_name: failed to find parent\n"); + } + goto fail; + } + } + last++; + res = fstatat(p->fd, last, &stat, AT_SYMLINK_NOFOLLOW); + if (res == -1) { + if (!retries) { + fuse_log(FUSE_LOG_WARNING, + "lo_parent_and_name: failed to stat last\n"); + } + goto fail_unref; + } + if (stat.st_dev != inode->dev || stat.st_ino != inode->ino) { + if (!retries) { + fuse_log(FUSE_LOG_WARNING, + "lo_parent_and_name: failed to match last\n"); + } + goto fail_unref; + } + *parent = p; + memmove(path, last, strlen(last) + 1); + + return 0; + +fail_unref: + unref_inode(lo, p, 1); +fail: + if (retries) { + retries--; + goto retry; + } +fail_noretry: + errno = EIO; + return -1; +} + +static int utimensat_empty(struct lo_data *lo, struct lo_inode *inode, + const struct timespec *tv) +{ + int res; + struct lo_inode *parent; + char path[PATH_MAX]; if (inode->is_symlink) { - res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); + res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH); if (res == -1 && errno == EINVAL) { /* Sorry, no race free way to set times on symlink. */ - errno = EPERM; + if (lo->norace) { + errno = EPERM; + } else { + goto fallback; + } } return res; } - sprintf(procname, "/proc/self/fd/%i", inode->fd); + sprintf(path, "/proc/self/fd/%i", inode->fd); + + return utimensat(AT_FDCWD, path, tv, 0); - return utimensat(AT_FDCWD, procname, tv, 0); +fallback: + res = lo_parent_and_name(lo, inode, path, &parent); + if (res != -1) { + res = utimensat(parent->fd, path, tv, AT_SYMLINK_NOFOLLOW); + unref_inode(lo, parent, 1); + } + + return res; } static int lo_fi_fd(fuse_req_t req, struct fuse_file_info *fi) @@ -387,6 +497,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, { int saverr; char procname[64]; + struct lo_data *lo = lo_data(req); struct lo_inode *inode; int ifd; int res; @@ -459,7 +570,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, if (fi) { res = futimens(fd, tv); } else { - res = utimensat_empty_nofollow(inode, tv); + res = utimensat_empty(lo, inode, tv); } if (res == -1) { goto out_err; @@ -692,24 +803,38 @@ static void lo_symlink(fuse_req_t req, const char *link, fuse_ino_t parent, lo_mknod_symlink(req, parent, name, S_IFLNK, 0, link); } -static int linkat_empty_nofollow(struct lo_inode *inode, int dfd, - const char *name) +static int linkat_empty_nofollow(struct lo_data *lo, struct lo_inode *inode, + int dfd, const char *name) { int res; - char procname[64]; + struct lo_inode *parent; + char path[PATH_MAX]; if (inode->is_symlink) { res = linkat(inode->fd, "", dfd, name, AT_EMPTY_PATH); if (res == -1 && (errno == ENOENT || errno == EINVAL)) { /* Sorry, no race free way to hard-link a symlink. */ - errno = EPERM; + if (lo->norace) { + errno = EPERM; + } else { + goto fallback; + } } return res; } - sprintf(procname, "/proc/self/fd/%i", inode->fd); + sprintf(path, "/proc/self/fd/%i", inode->fd); + + return linkat(AT_FDCWD, path, dfd, name, AT_SYMLINK_FOLLOW); + +fallback: + res = lo_parent_and_name(lo, inode, path, &parent); + if (res != -1) { + res = linkat(parent->fd, path, dfd, name, 0); + unref_inode(lo, parent, 1); + } - return linkat(AT_FDCWD, procname, dfd, name, AT_SYMLINK_FOLLOW); + return res; } static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, @@ -731,7 +856,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, e.attr_timeout = lo->timeout; e.entry_timeout = lo->timeout; - res = linkat_empty_nofollow(inode, lo_fd(req, parent), name); + res = linkat_empty_nofollow(lo, inode, lo_fd(req, parent), name); if (res == -1) { goto out_err; } @@ -1544,7 +1669,7 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name, } if (inode->is_symlink) { - /* Sorry, no race free way to setxattr on symlink. */ + /* Sorry, no race free way to removexattr on symlink. */ saverr = EPERM; goto out; }