proc: more robust bulk read test

/proc may not be mounted and test will exit successfully.

Ensure proc is mounted at /proc.

Link: http://lkml.kernel.org/r/20190209105613.GA10384@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/tools/testing/selftests/proc/read.c b/tools/testing/selftests/proc/read.c
index b2bd8da58efe..b3ef9e14d6cc 100644
--- a/tools/testing/selftests/proc/read.c
+++ b/tools/testing/selftests/proc/read.c
@@ -26,8 +26,10 @@
 #include <dirent.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include <string.h>
 #include <sys/stat.h>
+#include <sys/vfs.h>
 #include <fcntl.h>
 #include <unistd.h>
 
@@ -123,10 +125,22 @@ static void f(DIR *d, unsigned int level)
 int main(void)
 {
         DIR *d;
+        struct statfs sfs;
 
         d = opendir("/proc");
         if (!d)
                 return 4;
+
+        /* Ensure /proc is proc. */
+        if (fstatfs(dirfd(d), &sfs) == -1) {
+                return 1;
+        }
+        if (sfs.f_type != 0x9fa0) {
+                fprintf(stderr, "error: unexpected f_type %lx\n", (long)sfs.f_type);
+                return 2;
+        }
+
         f(d, 0);
+
         return 0;
 }