fix(fuse-tests): drop glog globals from TestWriteBufferCap mount options

-logtostderr and -v are glog globals parsed before the subcommand; weed
mount's flag set rejects them, so the mount process exited with a usage
error and the test silently ran against the local disk (masked until
waitForMount started verifying a real mount). glog already writes to
stderr here by default, so the options were also redundant.

test/fuse_integration/framework_test.go

@@ -333,11 +333,19 @@ func (f *FuseTestFramework) waitForService(addr string, timeout time.Duration) e
 	return fmt.Errorf("service at %s not ready within timeout", addr)
 }
 
-// waitForMount waits for the FUSE mount to be ready
+// waitForMount waits for the FUSE mount to be ready. A stat/ReadDir probe
+// alone is not enough: the bare mount point directory passes both before the
+// mount process finishes starting, letting tests race ahead and write to the
+// local disk underneath the mount. The mount point's device ID differing from
+// its parent's confirms a filesystem is actually mounted there.
 func (f *FuseTestFramework) waitForMount(timeout time.Duration) error {
+	parentDev, err := deviceID(filepath.Dir(f.mountPoint))
+	if err != nil {
+		return fmt.Errorf("stat mount point parent: %v", err)
+	}
 	deadline := time.Now().Add(timeout)
 	for time.Now().Before(deadline) {
-		if _, err := os.Stat(f.mountPoint); err == nil {
+		if dev, err := deviceID(f.mountPoint); err == nil && dev != parentDev {
 			if _, err := os.ReadDir(f.mountPoint); err == nil {
 				return nil
 			}
@@ -347,6 +355,15 @@ func (f *FuseTestFramework) waitForMount(timeout time.Duration) error {
 	return fmt.Errorf("mount point not ready within timeout")
 }
 
+// deviceID returns the device ID of the filesystem containing path.
+func deviceID(path string) (uint64, error) {
+	var st syscall.Stat_t
+	if err := syscall.Stat(path, &st); err != nil {
+		return 0, err
+	}
+	return uint64(st.Dev), nil
+}
+
 // findWeedBinary locates the weed binary.
 func findWeedBinary() string {
 	if p, err := exec.LookPath("weed"); err == nil {

test/fuse_integration/write_buffer_cap_test.go

@@ -88,13 +88,9 @@ func writeBufferCapConfig(debugPort int) *TestConfig {
 			"-writeBufferSizeMB=16",
 			"-debug=true",
 			fmt.Sprintf("-debug.port=%d", debugPort),
-			// Route glog to stderr so the framework's process log
-			// capture actually contains something — by default weed
-			// sends glog to /tmp/weed.* files which the CI artifact
-			// upload step never sees. Critical for diagnosing
-			// upload/saveToStorage errors on Linux runs.
-			"-logtostderr=true",
-			"-v=2",
+			// NOTE: glog flags (-logtostderr, -v) are globals parsed
+			// before the subcommand; passing them here makes weed
+			// mount exit with a usage error before ever mounting.
 		},
 		SkipCleanup: false,
 	}