Merge tag 'pull-9p-20241128' of https://github.com/cschoenebeck/qemu into staging

* Fix open-unlink-fstat idiom on Linux guests.

* Add test to verify this behaviour.

* Cleanup patches.

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# gpg: Signature made Thu 28 Nov 2024 18:53:45 GMT
# gpg:                using RSA key 96D8D110CF7AF8084F88590134C2B58765A47395
# gpg:                issuer "qemu_oss@crudebyte.com"
# gpg: Good signature from "Christian Schoenebeck <qemu_oss@crudebyte.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: ECAB 1A45 4014 1413 BA38  4926 30DB 47C3 A012 D5F4
#      Subkey fingerprint: 96D8 D110 CF7A F808 4F88  5901 34C2 B587 65A4 7395

* tag 'pull-9p-20241128' of https://github.com/cschoenebeck/qemu:
  tests/9p: also check 'Tgetattr' in 'use-after-unlink' test
  9pfs: fix 'Tgetattr' after unlink
  9pfs: remove obsolete comment in v9fs_getattr()
  tests/9p: add missing Rgetattr response name
  tests/9p: fix Rreaddir response name
  tests/9p: add 'use-after-unlink' test
  9pfs: cleanup V9fsFidState

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

4 files changed, 55 insertions, 7 deletions

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 9a291d1b51..578517739a 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1596,11 +1596,13 @@ static void coroutine_fn v9fs_getattr(void *opaque)
         retval = -ENOENT;
         goto out_nofid;
     }
-    /*
-     * Currently we only support BASIC fields in stat, so there is no
-     * need to look at request_mask.
-     */
-    retval = v9fs_co_lstat(pdu, &fidp->path, &stbuf);
+    if ((fidp->fid_type == P9_FID_FILE && fidp->fs.fd != -1) ||
+        (fidp->fid_type == P9_FID_DIR && fidp->fs.dir.stream))
+    {
+        retval = v9fs_co_fstat(pdu, fidp, &stbuf);
+    } else {
+        retval = v9fs_co_lstat(pdu, &fidp->path, &stbuf);
+    }
     if (retval < 0) {
         goto out;
     }
diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
index a6f59abccb..5e041e1f60 100644
--- a/hw/9pfs/9p.h
+++ b/hw/9pfs/9p.h
@@ -280,7 +280,6 @@ struct V9fsFidState {
     uid_t uid;
     int ref;
     bool clunked;
-    QSIMPLEQ_ENTRY(V9fsFidState) next;
     QSLIST_ENTRY(V9fsFidState) reclaim_next;
 };
 
diff --git a/tests/qtest/libqos/virtio-9p-client.c b/tests/qtest/libqos/virtio-9p-client.c
index b8adc8d4b9..98b77db51d 100644
--- a/tests/qtest/libqos/virtio-9p-client.c
+++ b/tests/qtest/libqos/virtio-9p-client.c
@@ -235,10 +235,11 @@ static const char *rmessage_name(uint8_t id)
         id == P9_RMKDIR ? "RMKDIR" :
         id == P9_RLCREATE ? "RLCREATE" :
         id == P9_RSYMLINK ? "RSYMLINK" :
+        id == P9_RGETATTR ? "RGETATTR" :
         id == P9_RLINK ? "RLINK" :
         id == P9_RUNLINKAT ? "RUNLINKAT" :
         id == P9_RFLUSH ? "RFLUSH" :
-        id == P9_RREADDIR ? "READDIR" :
+        id == P9_RREADDIR ? "RREADDIR" :
         "<unknown>";
 }
 
diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index 3c8cd235cf..ab3a12c816 100644
--- a/tests/qtest/virtio-9p-test.c
+++ b/tests/qtest/virtio-9p-test.c
@@ -693,6 +693,50 @@ static void fs_unlinkat_hardlink(void *obj, void *data,
     g_assert(stat(real_file, &st_real) == 0);
 }
 
+static void fs_use_after_unlink(void *obj, void *data,
+                                QGuestAllocator *t_alloc)
+{
+    QVirtio9P *v9p = obj;
+    v9fs_set_allocator(t_alloc);
+    static const uint32_t write_count = P9_MAX_SIZE / 2;
+    g_autofree char *real_file = virtio_9p_test_path("09/doa_file");
+    g_autofree char *buf = g_malloc0(write_count);
+    struct stat st_file;
+    struct v9fs_attr attr;
+    uint32_t fid_file;
+    uint32_t count;
+
+    tattach({ .client = v9p });
+
+    /* create a file "09/doa_file" and make sure it exists and is regular */
+    tmkdir({ .client = v9p, .atPath = "/", .name = "09" });
+    tlcreate({ .client = v9p, .atPath = "09", .name = "doa_file" });
+    g_assert(stat(real_file, &st_file) == 0);
+    g_assert((st_file.st_mode & S_IFMT) == S_IFREG);
+
+    /* request a FID for that regular file that we can work with next */
+    fid_file = twalk({
+        .client = v9p, .fid = 0, .path = "09/doa_file"
+    }).newfid;
+    g_assert(fid_file != 0);
+
+    /* now first open the file in write mode before ... */
+    tlopen({ .client = v9p, .fid = fid_file, .flags = O_WRONLY });
+    /* ... removing the file from file system */
+    tunlinkat({ .client = v9p, .atPath = "09", .name = "doa_file" });
+
+    /* file is removed, but we still have it open, so this should succeed */
+    tgetattr({
+        .client = v9p, .fid = fid_file, .request_mask = P9_GETATTR_BASIC,
+        .rgetattr.attr = &attr
+    });
+    count = twrite({
+        .client = v9p, .fid = fid_file, .offset = 0, .count = write_count,
+        .data = buf
+    }).count;
+    g_assert_cmpint(count, ==, write_count);
+}
+
 static void cleanup_9p_local_driver(void *data)
 {
     /* remove previously created test dir when test is completed */
@@ -758,6 +802,8 @@ static void register_virtio_9p_test(void)
     qos_add_test("local/hardlink_file", "virtio-9p", fs_hardlink_file, &opts);
     qos_add_test("local/unlinkat_hardlink", "virtio-9p", fs_unlinkat_hardlink,
                  &opts);
+    qos_add_test("local/use_after_unlink", "virtio-9p", fs_use_after_unlink,
+                 &opts);
 }
 
 libqos_init(register_virtio_9p_test);