sys_statvfs_test: fix expectation for Linux 6.7.

I'd assumed that it was _deliberate_ that filesystems like procfs
reported 0 here, but apparently not. Good news: this makes for a more
worthwhile test than we had previously (at least when run on a 6.7+
kernel).

Bug: http://b/321880382 (for sys_vfs_test)
Bug: http://b/319590754 (for sys_statvfs_test)
Test: treehugger
Change-Id: I0a63faa8ca359592a29d7bca1a40ecd94fd50044
(cherry picked from commit 7506c37386ad71060dee90cfa001b825b97aff84)

1 files changed, 11 insertions, 1 deletions

diff --git a/tests/sys_statvfs_test.cpp b/tests/sys_statvfs_test.cpp
index 1761e6a51..73b2a9681 100644
--- a/tests/sys_statvfs_test.cpp
+++ b/tests/sys_statvfs_test.cpp
@@ -28,9 +28,19 @@ template <typename StatVfsT> void Check(StatVfsT& sb) {
   EXPECT_EQ(4096U, sb.f_bsize);
   EXPECT_EQ(0U, sb.f_bfree);
   EXPECT_EQ(0U, sb.f_ffree);
-  EXPECT_EQ(0U, sb.f_fsid);
   EXPECT_EQ(255U, sb.f_namemax);
 
+  // Linux 6.7 requires that all filesystems have a non-zero fsid.
+  if (sb.f_fsid != 0U) {
+    // fs/libfs.c reuses the filesystem's device number.
+    struct stat proc_sb;
+    ASSERT_EQ(0, stat("/proc", &proc_sb));
+    EXPECT_EQ(proc_sb.st_dev, sb.f_fsid);
+  } else {
+    // Prior to that, the fsid for /proc was just 0.
+    EXPECT_EQ(0U, sb.f_fsid);
+  }
+
   // The kernel sets a private bit to indicate that f_flags is valid.
   // This flag is not supposed to be exposed to libc clients.
   static const uint32_t ST_VALID = 0x0020;