Re: [PATCH 7/8] tests/9pfs: add local Tlink test

[Christian Schoenebeck]

On Dienstag, 20. Oktober 2020 01:13:24 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 
> ---
>  tests/qtest/virtio-9p-test.c | 61 
>  1 file changed, 61 insertions(+)
> 
> diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
> index f7d18f6274..447d8e3344 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" :
> @@ -742,6 +743,33 @@ 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)
> +{

This hard-link test was actually motived by an issue that I recently 
encountered on a machine: it fails to create any hard links with 9p. This 
particular test case succeeds though.

I think the problem is that recent libvirt versions enable qemu's sandbox 
feature by default which filters syscalls. Fact is, any linkat() call fails on 
that machine with EACCES now. I couldn't reproduce it on my development 
machine yet though. I guess it's a difference in white/black-list seccomp 
config or something. Not sure yet if there is some change required on 9p side 
or whether it's really just a seccomp config issue.

P.S. Noisy days from my side, but this is probably the last batch of patches 
from my side in a while, unless I really need to fix something for that hard 
link isssue. We'll see ...

Best regards,
Christian Schoenebeck

[PATCH 7/8] tests/9pfs: add local Tlink test

[Christian Schoenebeck]

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 
---
 tests/qtest/virtio-9p-test.c | 61 
 1 file changed, 61 insertions(+)

diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index f7d18f6274..447d8e3344 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" :
@@ -742,6 +743,33 @@ 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)
@@ -1318,6 +1346,38 @@ 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;
+P9Req *req;
+uint32_t dfid, fid;
+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");
+
+fs_attach(v9p, NULL, t_alloc);
+fs_mkdir(v9p, data, t_alloc, "/", "07");
+fid = fs_lcreate(v9p, data, t_alloc, "07", "real_file");
+g_assert(stat(real_file, &st_real) == 0);
+g_assert((st_real.st_mode & S_IFMT) == S_IFREG);
+
+dfid = fs_walk_fid(v9p, data, t_alloc, "07");
+
+req = v9fs_tlink(v9p, dfid, fid, "hardlink_file", 0);
+v9fs_req_wait_for_reply(req, NULL);
+v9fs_rlink(req);
+
+/* 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");
@@ -1363,6 +1423,7 @@ static void register_virtio_9p_test(void)
 qos_add_test("local/unlinkat_file", "virtio-9p", fs_unlinkat_file, &opts);
 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);
-- 
2.20.1