Merge tag 'pull-9p-20250505' of https://github.com/cschoenebeck/qemu into staging

9pfs changes:

* Fixes for file descriptor reclaiming algorithm (i.e. when running
  towards host's allowed limit of max. open file descriptors).

* Additional fixes on use-after-unlink idiom (i.e. client operations on a
  file descriptor after file has been removed).

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# gpg: Signature made Mon 05 May 2025 05:50:37 EDT
# gpg:                using RSA key 96D8D110CF7AF8084F88590134C2B58765A47395
# gpg:                issuer "qemu_oss@crudebyte.com"
# gpg: Good signature from "Christian Schoenebeck <qemu_oss@crudebyte.com>" [unknown]
# gpg: WARNING: The key's User ID 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-20250505' of https://github.com/cschoenebeck/qemu:
  9pfs: fix 'total_open_fd' decrementation
  tests/9p: Test `Tsetattr` can truncate unlinked file
  tests/9p: add 'Tsetattr' request to test client
  9pfs: Introduce futimens file op
  9pfs: Introduce ftruncate file op
  9pfs: Don't use file descriptors in core code
  9pfs: local : Introduce local_fid_fd() helper
  9pfs: fix FD leak and reduce latency of v9fs_reclaim_fd()
  9pfs: fix concurrent v9fs_reclaim_fd() calls

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

3 files changed, 98 insertions, 0 deletions

diff --git a/tests/qtest/libqos/virtio-9p-client.c b/tests/qtest/libqos/virtio-9p-client.c
index 98b77db51d..6ab4501c6e 100644
--- a/tests/qtest/libqos/virtio-9p-client.c
+++ b/tests/qtest/libqos/virtio-9p-client.c
@@ -557,6 +557,55 @@ void v9fs_rgetattr(P9Req *req, v9fs_attr *attr)
     v9fs_req_free(req);
 }
 
+/*
+ * size[4] Tsetattr tag[2] fid[4] valid[4] mode[4] uid[4] gid[4] size[8]
+ *                  atime_sec[8] atime_nsec[8] mtime_sec[8] mtime_nsec[8]
+ */
+TSetAttrRes v9fs_tsetattr(TSetAttrOpt opt)
+{
+    P9Req *req;
+    uint32_t err;
+
+    g_assert(opt.client);
+
+    req = v9fs_req_init(
+        opt.client, 4/*fid*/ + 4/*valid*/ + 4/*mode*/ + 4/*uid*/ + 4/*gid*/ +
+        8/*size*/ + 8/*atime_sec*/ + 8/*atime_nsec*/ + 8/*mtime_sec*/ +
+        8/*mtime_nsec*/, P9_TSETATTR, opt.tag
+    );
+    v9fs_uint32_write(req, opt.fid);
+    v9fs_uint32_write(req, (uint32_t) opt.attr.valid);
+    v9fs_uint32_write(req, opt.attr.mode);
+    v9fs_uint32_write(req, opt.attr.uid);
+    v9fs_uint32_write(req, opt.attr.gid);
+    v9fs_uint64_write(req, opt.attr.size);
+    v9fs_uint64_write(req, opt.attr.atime_sec);
+    v9fs_uint64_write(req, opt.attr.atime_nsec);
+    v9fs_uint64_write(req, opt.attr.mtime_sec);
+    v9fs_uint64_write(req, opt.attr.mtime_nsec);
+    v9fs_req_send(req);
+
+    if (!opt.requestOnly) {
+        v9fs_req_wait_for_reply(req, NULL);
+        if (opt.expectErr) {
+            v9fs_rlerror(req, &err);
+            g_assert_cmpint(err, ==, opt.expectErr);
+        } else {
+            v9fs_rsetattr(req);
+        }
+        req = NULL; /* request was freed */
+    }
+
+    return (TSetAttrRes) { .req = req };
+}
+
+/* size[4] Rsetattr tag[2] */
+void v9fs_rsetattr(P9Req *req)
+{
+    v9fs_req_recv(req, P9_RSETATTR);
+    v9fs_req_free(req);
+}
+
 /* size[4] Treaddir tag[2] fid[4] offset[8] count[4] */
 TReadDirRes v9fs_treaddir(TReadDirOpt opt)
 {
diff --git a/tests/qtest/libqos/virtio-9p-client.h b/tests/qtest/libqos/virtio-9p-client.h
index 78228eb97d..e3221a3104 100644
--- a/tests/qtest/libqos/virtio-9p-client.h
+++ b/tests/qtest/libqos/virtio-9p-client.h
@@ -65,6 +65,16 @@ typedef struct v9fs_attr {
 #define P9_GETATTR_BASIC    0x000007ffULL /* Mask for fields up to BLOCKS */
 #define P9_GETATTR_ALL      0x00003fffULL /* Mask for ALL fields */
 
+#define P9_SETATTR_MODE         0x00000001UL
+#define P9_SETATTR_UID          0x00000002UL
+#define P9_SETATTR_GID          0x00000004UL
+#define P9_SETATTR_SIZE         0x00000008UL
+#define P9_SETATTR_ATIME        0x00000010UL
+#define P9_SETATTR_MTIME        0x00000020UL
+#define P9_SETATTR_CTIME        0x00000040UL
+#define P9_SETATTR_ATIME_SET    0x00000080UL
+#define P9_SETATTR_MTIME_SET    0x00000100UL
+
 struct V9fsDirent {
     v9fs_qid qid;
     uint64_t offset;
@@ -182,6 +192,28 @@ typedef struct TGetAttrRes {
     P9Req *req;
 } TGetAttrRes;
 
+/* options for 'Tsetattr' 9p request */
+typedef struct TSetAttrOpt {
+    /* 9P client being used (mandatory) */
+    QVirtio9P *client;
+    /* user supplied tag number being returned with response (optional) */
+    uint16_t tag;
+    /* file ID of file/dir whose attributes shall be modified (required) */
+    uint32_t fid;
+    /* new attribute values to be set by 9p server */
+    v9fs_attr attr;
+    /* only send Tsetattr request but not wait for a reply? (optional) */
+    bool requestOnly;
+    /* do we expect an Rlerror response, if yes which error code? (optional) */
+    uint32_t expectErr;
+} TSetAttrOpt;
+
+/* result of 'Tsetattr' 9p request */
+typedef struct TSetAttrRes {
+    /* if requestOnly was set: request object for further processing */
+    P9Req *req;
+} TSetAttrRes;
+
 /* options for 'Treaddir' 9p request */
 typedef struct TReadDirOpt {
     /* 9P client being used (mandatory) */
@@ -470,6 +502,8 @@ TWalkRes v9fs_twalk(TWalkOpt opt);
 void v9fs_rwalk(P9Req *req, uint16_t *nwqid, v9fs_qid **wqid);
 TGetAttrRes v9fs_tgetattr(TGetAttrOpt);
 void v9fs_rgetattr(P9Req *req, v9fs_attr *attr);
+TSetAttrRes v9fs_tsetattr(TSetAttrOpt opt);
+void v9fs_rsetattr(P9Req *req);
 TReadDirRes v9fs_treaddir(TReadDirOpt);
 void v9fs_rreaddir(P9Req *req, uint32_t *count, uint32_t *nentries,
                    struct V9fsDirent **entries);
diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index ab3a12c816..ac38ccf595 100644
--- a/tests/qtest/virtio-9p-test.c
+++ b/tests/qtest/virtio-9p-test.c
@@ -20,6 +20,7 @@
 #define tversion(...) v9fs_tversion((TVersionOpt) __VA_ARGS__)
 #define tattach(...) v9fs_tattach((TAttachOpt) __VA_ARGS__)
 #define tgetattr(...) v9fs_tgetattr((TGetAttrOpt) __VA_ARGS__)
+#define tsetattr(...) v9fs_tsetattr((TSetAttrOpt) __VA_ARGS__)
 #define treaddir(...) v9fs_treaddir((TReadDirOpt) __VA_ARGS__)
 #define tlopen(...) v9fs_tlopen((TLOpenOpt) __VA_ARGS__)
 #define twrite(...) v9fs_twrite((TWriteOpt) __VA_ARGS__)
@@ -735,6 +736,20 @@ static void fs_use_after_unlink(void *obj, void *data,
         .data = buf
     }).count;
     g_assert_cmpint(count, ==, write_count);
+
+    /* truncate file to (arbitrarily chosen) size 2001 */
+    tsetattr({
+        .client = v9p, .fid = fid_file, .attr = (v9fs_attr) {
+            .valid = P9_SETATTR_SIZE,
+            .size = 2001
+        }
+     });
+    /* truncate apparently succeeded, let's double-check the size */
+    tgetattr({
+        .client = v9p, .fid = fid_file, .request_mask = P9_GETATTR_BASIC,
+        .rgetattr.attr = &attr
+    });
+    g_assert_cmpint(attr.size, ==, 2001);
 }
 
 static void cleanup_9p_local_driver(void *data)