[PATCH] generic/791: don't run if kernel misses FANOTIFY

If FANOTIFY=no in the kernel, then fs-monitor will fail to start. Fix
fs-monitor error codes to detect and skip the test on "Function not
implemented" code.

Signed-off-by: Andrey Albershteyn <[email protected]>
---
 src/fs-monitor.c  |  9 ++++++---
 tests/generic/791 | 10 +++++++++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/fs-monitor.c b/src/fs-monitor.c
index 0cf09677a3ef..28436ec2336f 100644
--- a/src/fs-monitor.c
+++ b/src/fs-monitor.c
@@ -117,6 +117,7 @@ next_event:
 int main(int argc, char **argv)
 {
 	int fd;
+	int error;
 
 	char buffer[BUFSIZ];
 
@@ -126,15 +127,17 @@ int main(int argc, char **argv)
 	}
 
 	fd = fanotify_init(FAN_CLASS_NOTIF|FAN_REPORT_FID, O_RDONLY);
+	error = errno;
 	if (fd < 0) {
 		perror("fanotify_init");
-		errx(1, "fanotify_init");
+		errx(error, "fanotify_init");
 	}
 
 	if (fanotify_mark(fd, FAN_MARK_ADD|FAN_MARK_FILESYSTEM,
 			  FAN_FS_ERROR, AT_FDCWD, argv[1])) {
+		error = errno;
 		perror("fanotify_mark");
-		errx(1, "fanotify_mark");
+		errx(errno, "fanotify_mark");
 	}
 
 	printf("fanotify active\n");
@@ -144,7 +147,7 @@ int main(int argc, char **argv)
 		int n = read(fd, buffer, BUFSIZ);
 
 		if (n < 0)
-			errx(1, "read");
+			errx(errno, "read");
 
 		handle_notifications(buffer, n);
 	}
diff --git a/tests/generic/791 b/tests/generic/791
index 90242292cba2..1d3a6c181011 100755
--- a/tests/generic/791
+++ b/tests/generic/791
@@ -123,10 +123,18 @@ fi
 _dmerror_unmount
 _dmerror_mount
 
-$here/src/fs-monitor $SCRATCH_MNT > $tmp.fsmonitor &
+$here/src/fs-monitor $SCRATCH_MNT > $tmp.fsmonitor 2>&1 &
 fsmonitor_pid=$!
 sleep 1
 
+if ! kill -0 $fsmonitor_pid 2>/dev/null; then
+	wait $fsmonitor_pid
+	# Function not implemented
+	if [ $? -eq 38 ]; then
+		_notrun "Kernel doesn't support fanotify"
+	fi
+fi
+
 _dmerror_mark_range_bad $bad_sector $bad_len
 
 cat >> $seqres.full << ENDL
-- 
2.51.2