[PATCH v2 1/2] fanotify: fix crash when running multiple iterations

[AnonymeMeow]

This commit fixes ./fanotify13 -i10 crash by restoring the deleted objects
every time a test finishes.

This commit also fixes ./fanotify21 -i10 crash by remounting the read-only
mount (if the mount is remounted read-only during the test) back to
read-write every time a test finishes.

Signed-off-by: AnonymeMeow <anonymemeow@xxxxxxxxx>
---

On 2026-05-27 09:23:12+02:00, Petr Vorel wrote:
> @AnonymeMeow nit: if you put whole conversation after --- (below), it will not
> be part of the commit message when one applies the patch. And here should be a
> proper commit message.

Thank you for pointing this out, I will be more mindful the next time
(this time).

> Also I found that fanotify21.c on the current master fails when running more
> than 1 iteration:

Thanks for testing my patch, I didn't know that the standalone test binary
supports the -i option to specify the number of iterations. Running
multiple iterations through kirk's -i option seems to work fine.

I then tested all fanotify tests with the -i option and found that
fanotify13 also crashed when running multiple iterations. I fixed both
fanotify13 and fanotify21 in this patch. So now all fanotify tests pass
with the -i option.

With Best Regards,
AnonymeMeow

---
 .../kernel/syscalls/fanotify/fanotify13.c     | 20 +++++++++++++++++++
 .../kernel/syscalls/fanotify/fanotify21.c     | 13 +++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/testcases/kernel/syscalls/fanotify/fanotify13.c b/testcases/kernel/syscalls/fanotify/fanotify13.c
index 76d40eaf7..540e0b483 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify13.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify13.c
@@ -137,6 +137,16 @@ static void delete_objects(void)
 	}
 }
 
+static void clean_upper_dir(void)
+{
+	unsigned int i;
+
+	SAFE_MOUNT(OVL_UPPER, MOUNT_PATH, "none", MS_BIND, NULL);
+	for (i = 0; i < ARRAY_SIZE(objects); i++)
+		SAFE_UNLINK(objects[i].path);
+	SAFE_UMOUNT(MOUNT_PATH);
+}
+
 static void get_object_stats(void)
 {
 	unsigned int i;
@@ -340,6 +350,15 @@ static void do_test(unsigned int number)
 			"Did not get an expected event (expected: %llx)",
 			event_set[i].expected_mask);
 	}
+
+	if (tc->mask & FAN_DELETE_SELF) {
+		if (tst_variant & 1) {
+			clean_upper_dir();
+		} else {
+			create_objects();
+			get_object_stats();
+		}
+	}
 out:
 	SAFE_CLOSE(fanotify_fd);
 }
@@ -417,6 +436,7 @@ static void do_cleanup(void)
 	if (ovl_bind_mounted)
 		SAFE_UMOUNT(MOUNT_PATH);
 	if (bind_mounted) {
+		delete_objects();
 		SAFE_UMOUNT(MOUNT_PATH);
 		SAFE_RMDIR(MOUNT_PATH);
 	}
diff --git a/testcases/kernel/syscalls/fanotify/fanotify21.c b/testcases/kernel/syscalls/fanotify/fanotify21.c
index 340fb0018..2e3dbd4bd 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify21.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify21.c
@@ -199,7 +199,7 @@ static void do_test(unsigned int num)
 	if (len < 0) {
 		if (tc->remount_ro && !fd_err && errno == EROFS) {
 			tst_res(TPASS, "cannot read event with rw fd from a ro fs");
-			return;
+			goto restore_rw_mount;
 		}
 		tst_brk(TBROK | TERRNO, "reading fanotify events failed");
 	} else if (tc->remount_ro && !fd_err) {
@@ -346,6 +346,17 @@ next_event:
 		if (event_pidfd_fdinfo)
 			free(event_pidfd_fdinfo);
 	}
+
+restore_rw_mount:
+	if (tc->remount_ro) {
+		/* SAFE_MOUNT fails to remount FUSE */
+		if (mount(tst_device->dev, MOUNT_PATH, tst_device->fs_type,
+			  MS_REMOUNT, NULL) != 0) {
+			tst_brk(TFAIL,
+				"filesystem %s failed to remount read-write",
+				tst_device->fs_type);
+		}
+	}
 }
 
 static void do_cleanup(void)
-- 
2.54.0