fanotify13: Verify that we did not get an extra event

For example, verify that we did not get an event on a directory object
without requesting FAN_ONDIR.  Also, report a test failure if no events
received at all instead of blocking on read of fanotify_fd.

With this change, the test fails with overlayfs variants over btrfs,
because the size of fid of overalyfs over btrfs is about 90 bytes and
the events on the three objects do not all fit into a single 256 bytes
buffer read. Increase the size of the events buffer to fix this failure.

Link: https://lore.kernel.org/ltp/[email protected]/
Reviewed-by: Petr Vorel <[email protected]>
Signed-off-by: Amir Goldstein <[email protected]>

Author: amir73il

testcases/kernel/syscalls/fanotify/fanotify13.c

@@ -34,12 +34,12 @@
 #include "fanotify.h"
 
 #define PATH_LEN 128
-#define BUF_SIZE 256
+#define BUF_SIZE 1024
 #define DIR_ONE "dir_one"
 #define FILE_ONE "file_one"
 #define FILE_TWO "file_two"
 #define MOUNT_PATH "tstmnt"
-#define EVENT_MAX ARRAY_SIZE(objects)
+#define EVENT_MAX (ARRAY_SIZE(objects)+1)
 #define DIR_PATH_ONE MOUNT_PATH"/"DIR_ONE
 #define FILE_PATH_ONE MOUNT_PATH"/"FILE_ONE
 #define FILE_PATH_TWO MOUNT_PATH"/"FILE_TWO
@@ -130,10 +130,15 @@ static int setup_marks(unsigned int fd, struct test_case_t *tc)
 		SAFE_FANOTIFY_MARK(fd, FAN_MARK_ADD | mark->flag, tc->mask,
 				   AT_FDCWD, objects[i].path);
 
-		/* Setup the expected mask for each generated event */
+		/*
+		 * Setup the expected mask for each generated event.
+		 * No events are expected on directory without FAN_ONDIR.
+		 */
 		event_set[i].expected_mask = tc->mask;
 		if (!objects[i].is_dir)
 			event_set[i].expected_mask &= ~FAN_ONDIR;
+		else if (!(event_set[i].expected_mask & FAN_ONDIR))
+			event_set[i].expected_mask = 0;
 	}
 	return 0;
 }
@@ -163,7 +168,8 @@ static void do_test(unsigned int number)
 		return;
 	}
 
-	fanotify_fd = SAFE_FANOTIFY_INIT(FAN_CLASS_NOTIF | FAN_REPORT_FID, O_RDONLY);
+	fanotify_fd = SAFE_FANOTIFY_INIT(FAN_CLASS_NOTIF | FAN_REPORT_FID |
+					 FAN_NONBLOCK, O_RDONLY);
 
 	/*
 	 * Place marks on a set of objects and setup the expected masks
@@ -279,6 +285,16 @@ static void do_test(unsigned int number)
 			FSID_VAL_MEMBER(event_fid->fsid, 1),
 			*(unsigned long *) event_file_handle->f_handle);
 	}
+
+	/*
+	 * Verify that we did not get an extra event, for example, that we did
+	 * not get an event on directory without FAN_ONDIR.
+	 */
+	if (event_set[i].expected_mask) {
+		tst_res(TFAIL,
+			"Did not get an expected event (expected: %llx)",
+			event_set[i].expected_mask);
+	}
 out:
 	SAFE_CLOSE(fanotify_fd);
 }