tools/testing/selftests/vm/gup_benchmark.c: allow user specified file

Allow a user to specify a file to map by adding a new option, '-f',
providing a means to test various file backings.

If not specified, the benchmark will use a private mapping of /dev/zero,
which produces an anonymous mapping as before.

[akpm@linux-foundation.org: avoid using comma operator]
Link: http://lkml.kernel.org/r/20181010195605.10689-4-keith.busch@intel.com
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/tools/testing/selftests/vm/gup_benchmark.c b/tools/testing/selftests/vm/gup_benchmark.c
index b2082df8beb4..43a2d60e0e93 100644
--- a/tools/testing/selftests/vm/gup_benchmark.c
+++ b/tools/testing/selftests/vm/gup_benchmark.c
@@ -31,11 +31,12 @@ int main(int argc, char **argv)
 {
         struct gup_benchmark gup;
         unsigned long size = 128 * MB;
-        int i, fd, opt, nr_pages = 1, thp = -1, repeats = 1, write = 0;
+        int i, fd, filed, opt, nr_pages = 1, thp = -1, repeats = 1, write = 0;
         int cmd = GUP_FAST_BENCHMARK;
+        char *file = "/dev/zero";
         char *p;
 
-        while ((opt = getopt(argc, argv, "m:r:n:tTLU")) != -1) {
+        while ((opt = getopt(argc, argv, "m:r:n:f:tTLU")) != -1) {
                 switch (opt) {
                 case 'm':
                         size = atoi(optarg) * MB;
@@ -61,11 +62,20 @@ int main(int argc, char **argv)
                 case 'w':
                         write = 1;
                         break;
+                case 'f':
+                        file = optarg;
+                        break;
                 default:
                         return -1;
                 }
         }
 
+        filed = open(file, O_RDWR|O_CREAT);
+        if (filed < 0) {
+                perror("open");
+                exit(filed);
+        }
+
         gup.nr_pages_per_call = nr_pages;
         gup.flags = write;
 
@@ -73,8 +83,7 @@ int main(int argc, char **argv)
         if (fd == -1)
                 perror("open"), exit(1);
 
-        p = mmap(NULL, size, PROT_READ | PROT_WRITE,
-                        MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+        p = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, filed, 0);
         if (p == MAP_FAILED)
                 perror("mmap"), exit(1);
         gup.addr = (unsigned long)p;