On Mittwoch, 21. Oktober 2020 14:51:09 CEST Christian Schoenebeck wrote: > This test case uses a Tlink request to create a hard link to a regular > file using the 9pfs 'local' fs driver. > > Signed-off-by: Christian Schoenebeck <qemu_...@crudebyte.com> > --- > tests/qtest/virtio-9p-test.c | 71 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 71 insertions(+) > > diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c > index 33cba24b18..460fa49fe3 100644 > --- a/tests/qtest/virtio-9p-test.c > +++ b/tests/qtest/virtio-9p-test.c > @@ -260,6 +260,7 @@ static const char *rmessage_name(uint8_t id) > id == P9_RMKDIR ? "RMKDIR" : > id == P9_RLCREATE ? "RLCREATE" : > id == P9_RSYMLINK ? "RSYMLINK" : > + id == P9_RLINK ? "RLINK" : > id == P9_RUNLINKAT ? "RUNLINKAT" : > id == P9_RFLUSH ? "RFLUSH" : > id == P9_RREADDIR ? "READDIR" : > @@ -767,6 +768,33 @@ static void v9fs_rsymlink(P9Req *req, v9fs_qid *qid) > v9fs_req_free(req); > } > > +/* size[4] Tlink tag[2] dfid[4] fid[4] name[s] */ > +static P9Req *v9fs_tlink(QVirtio9P *v9p, uint32_t dfid, uint32_t fid, > + const char *name, uint16_t tag) > +{ > + P9Req *req; > + > + uint32_t body_size = 4 + 4; > + uint16_t string_size = v9fs_string_size(name); > + > + g_assert_cmpint(body_size, <=, UINT32_MAX - string_size); > + body_size += string_size; > + > + req = v9fs_req_init(v9p, body_size, P9_TLINK, tag); > + v9fs_uint32_write(req, dfid); > + v9fs_uint32_write(req, fid); > + v9fs_string_write(req, name); > + v9fs_req_send(req); > + return req; > +} > + > +/* size[4] Rlink tag[2] */ > +static void v9fs_rlink(P9Req *req) > +{ > + v9fs_req_recv(req, P9_RLINK); > + v9fs_req_free(req); > +} > + > /* size[4] Tunlinkat tag[2] dirfd[4] name[s] flags[4] */ > static P9Req *v9fs_tunlinkat(QVirtio9P *v9p, uint32_t dirfd, const char > *name, uint32_t flags, uint16_t tag) > @@ -1142,6 +1170,21 @@ static void do_symlink(QVirtio9P *v9p, const char > *path, const char *clink, g_free(name); > } > > +/* create a hard link named @a clink in directory @a path pointing to @a to > */ +static void do_hardlink(QVirtio9P *v9p, const char *path, const char > *clink, + const char *to) > +{ > + uint32_t dfid, fid; > + P9Req *req; > + > + dfid = do_walk(v9p, path); > + fid = do_walk(v9p, to); > + > + req = v9fs_tlink(v9p, dfid, fid, clink, 0); > + v9fs_req_wait_for_reply(req, NULL); > + v9fs_rlink(req); > +} > + > static void do_unlinkat(QVirtio9P *v9p, const char *atpath, const char > *rpath, uint32_t flags) > { > @@ -1321,6 +1364,33 @@ static void fs_unlinkat_symlink(void *obj, void > *data, g_free(real_file); > } > > +static void fs_hardlink_file(void *obj, void *data, QGuestAllocator > *t_alloc) +{ > + QVirtio9P *v9p = obj; > + alloc = t_alloc; > + struct stat st_real, st_link; > + char *real_file = virtio_9p_test_path("07/real_file"); > + char *hardlink_file = virtio_9p_test_path("07/hardlink_file"); > + > + do_attach(v9p); > + do_mkdir(v9p, "/", "07"); > + do_lcreate(v9p, "07", "real_file"); > + g_assert(stat(real_file, &st_real) == 0); > + g_assert((st_real.st_mode & S_IFMT) == S_IFREG); > + > + do_hardlink(v9p, "07", "hardlink_file", "07/real_file"); > + > + /* check if link exists now ... */ > + g_assert(stat(hardlink_file, &st_link) == 0); > + /* ... and it's a hard link, right? */ > + g_assert((st_link.st_mode & S_IFMT) == S_IFREG); > + g_assert(st_link.st_dev == st_real.st_dev); > + g_assert(st_link.st_ino == st_real.st_ino); > + > + g_free(hardlink_file); > + g_free(real_file); > +} > + > static void *assign_9p_local_driver(GString *cmd_line, void *arg) > { > virtio_9p_assign_local_driver(cmd_line, "security_model=mapped-xattr"); > @@ -1367,6 +1437,7 @@ static void register_virtio_9p_test(void) > qos_add_test("local/symlink_file", "virtio-9p", fs_symlink_file, > &opts); qos_add_test("local/unlinkat_symlink", "virtio-9p", > fs_unlinkat_symlink, &opts); > + qos_add_test("local/hardlink_file", "virtio-9p", fs_hardlink_file, > &opts); } > > libqos_init(register_virtio_9p_test);
Ok, I found the problem on the mentioned box that failed to create hard links with 9p: it is libvirt auto generating AppArmor policy rules for 9p export pathes, which libvirt generates with "rw" AA (AppArmor) permissions. Once I manually adjusted the AA rule to "rwl", creating hard links worked again. I guess I'll send a patch for libvirt to change that. At least IMO creating hard links with 9pfs is a very basic operation and should be enabled for the respective 9p export path by default. Actually I think it should also include "k" which means "file locking", as file locking is also a fundamental operation with 9pfs, right? Best regards, Christian Schoenebeck