[PATCH v2 3/3] common/rc: notrun if io_uring is disabled by sysctl

[Zorro Lang <zlang@kernel.org>]

If kernel supports io_uring, userspace still can/might disable that
supporting by set /proc/sys/kernel/io_uring_disabled=2. Let's notrun
if io_uring is disabled by that way.

Signed-off-by: Zorro Lang <zlang@kernel.org>
---
 README        |  6 ++++++
 common/rc     | 10 ++++++++++
 src/feature.c | 19 ++++++++++++-------
 3 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/README b/README
index c46690c4..477136de 100644
--- a/README
+++ b/README
@@ -142,6 +142,12 @@ Setup Environment
    https://www.lscdweb.com/registered/udf_verifier.html, then copy the udf_test
    binary to xfstests/src/.
 
+8. (optional) To do io_uring related testing, please make sure below 3 things:
+     1) kernel is built with CONFIG_IO_URING=y
+     2) sysctl -w kernel.io_uring_disabled=0 (or set it to 2 to disable io_uring
+        testing dynamically if kernel supports)
+     3) install liburing development package contains liburing.h before building
+        fstests
 
 For example, to run the tests with loopback partitions:
 
diff --git a/common/rc b/common/rc
index 50dde313..1406d8d9 100644
--- a/common/rc
+++ b/common/rc
@@ -2317,6 +2317,8 @@ _require_aiodio()
 # this test requires that the kernel supports IO_URING
 _require_io_uring()
 {
+	local n
+
 	$here/src/feature -R
 	case $? in
 	0)
@@ -2324,6 +2326,14 @@ _require_io_uring()
 	1)
 		_notrun "kernel does not support IO_URING"
 		;;
+	2)
+		n=$(sysctl -n kernel.io_uring_disabled 2>/dev/null)
+		if [ "$n" != "0" ];then
+			_notrun "io_uring isn't enabled totally by admin"
+		else
+			_fail "unexpected EPERM error, please check selinux or something else"
+		fi
+		;;
 	*)
 		_fail "unexpected error testing for IO_URING support"
 		;;
diff --git a/src/feature.c b/src/feature.c
index 941f96fb..7e474ce5 100644
--- a/src/feature.c
+++ b/src/feature.c
@@ -232,15 +232,20 @@ check_uring_support(void)
 	int err;
 
 	err = io_uring_queue_init(1, &ring, 0);
-	if (err == 0)
+	switch (err) {
+	case 0:
 		return 0;
-
-	if (err == -ENOSYS) /* CONFIG_IO_URING=n */
+	case -ENOSYS:
+		/* CONFIG_IO_URING=n */
 		return 1;
-
-	fprintf(stderr, "unexpected error from io_uring_queue_init(): %s\n",
-		strerror(-err));
-	return 2;
+	case -EPERM:
+		/* Might be due to sysctl io_uring_disabled isn't 0 */
+		return 2;
+	default:
+		fprintf(stderr, "unexpected error from io_uring_queue_init(): %s\n",
+			strerror(-err));
+		return 100;
+	}
 #else
 	/* liburing is unavailable, assume IO_URING is unsupported */
 	return 1;
-- 
2.43.0