[PATCH v2 2/3] fsstress: bypass io_uring testing if io_uring_queue_init returns EPERM

[Zorro Lang <zlang@kernel.org>]

I found the io_uring testing still fails as:
  io_uring_queue_init failed
even if kernel supports io_uring feature.

That because of the /proc/sys/kernel/io_uring_disabled isn't 0.

Different value means:
  0 All processes can create io_uring instances as normal.
  1 io_uring creation is disabled (io_uring_setup() will fail with
    -EPERM) for unprivileged processes not in the io_uring_group
    group. Existing io_uring instances can still be used.  See the
    documentation for io_uring_group for more information.
  2 io_uring creation is disabled for all processes. io_uring_setup()
    always fails with -EPERM. Existing io_uring instances can still
    be used.

So besides the CONFIG_IO_URING kernel config, there's another switch
can on or off the io_uring supporting. And the "2" or "1" might be
the default on some systems.

On this situation the io_uring_queue_init returns -EPERM, so I change
the fsstress to ignore io_uring testing if io_uring_queue_init returns
-ENOSYS or -EPERM. And print different verbose message for debug.

Signed-off-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
---
 ltp/fsstress.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/ltp/fsstress.c b/ltp/fsstress.c
index 4fc50efb..9d2631f7 100644
--- a/ltp/fsstress.c
+++ b/ltp/fsstress.c
@@ -762,7 +762,12 @@ int main(int argc, char **argv)
 #endif
 #ifdef URING
 			have_io_uring = true;
-			/* If ENOSYS, just ignore uring, other errors are fatal. */
+			/*
+			 * If ENOSYS, just ignore uring, due to kernel doesn't support it.
+			 * If EPERM, maybe due to sysctl kernel.io_uring_disabled isn't 0,
+			 *           or some selinux policies, etc.
+			 * Other errors are fatal.
+			 */
 			c = io_uring_queue_init(URING_ENTRIES, &ring, 0);
 			switch(c){
 			case 0:
@@ -770,9 +775,16 @@ int main(int argc, char **argv)
 				break;
 			case -ENOSYS:
 				have_io_uring = false;
+				if (verbose)
+					printf("io_uring isn't supported by kernel\n");
+				break;
+			case -EPERM:
+				have_io_uring = false;
+				if (verbose)
+					printf("io_uring isn't allowed, check io_uring_disabled sysctl or selinux policy\n");
 				break;
 			default:
-				fprintf(stderr, "io_uring_queue_init failed\n");
+				fprintf(stderr, "io_uring_queue_init failed, errno=%d\n", -c);
 				exit(1);
 			}
 #endif
-- 
2.43.0