fuse: diagnostic FLUSH interrupt

We add dummy interrupt handling for the FLUSH
fuse message. It can be enabled by the
"--fuse-flush-handle-interrupt" hidden command line
option, or "-ofuse-flush-handle-interrupt=yes"
mount option.

It serves no other than diagnostic & demonstational
purposes -- to exercise the interrupt handling framework
a bit and to give an usage example.

Documentation is also provided that showcases interrupt
handling via FLUSH.

Change-Id: I522f1e798501d06b74ac3592a5f73c1ab0590c60
updates: #465
Signed-off-by: Csaba Henk <csaba@redhat.com>

2 files changed, 94 insertions, 0 deletions

diff --git a/tests/features/interrupt.t b/tests/features/interrupt.t
new file mode 100644
index 00000000000..476d8755d2b
--- /dev/null
+++ b/tests/features/interrupt.t
@@ -0,0 +1,67 @@
+#!/bin/bash
+
+##Copy this file to tests/bugs before running run.sh (cp extras/test/bug-920583.t tests/bugs/)
+
+. $(dirname $0)/../include.rc
+. $(dirname $0)/../volume.rc
+
+TESTS_EXPECTED_IN_LOOP=4
+
+cleanup;
+logdir=`gluster --print-logdir`
+
+TEST build_tester $(dirname $0)/open_and_sleep.c
+
+## Start and create a volume
+TEST glusterd;
+TEST pidof glusterd;
+
+TEST $CLI volume create $V0 replica 2 stripe 2 $H0:$B0/${V0}{1,2,3,4,5,6,7,8};
+
+## Verify volume is is created
+EXPECT "$V0" volinfo_field $V0 'Volume Name';
+EXPECT 'Created' volinfo_field $V0 'Status';
+
+## Start volume and verify
+TEST $CLI volume start $V0;
+EXPECT 'Started' volinfo_field $V0 'Status';
+
+function log-file-name()
+{
+    logfilename=$M0".log"
+    echo ${logfilename:1} | tr / -
+}
+
+log_file=$logdir"/"`log-file-name`
+
+function test_interrupt {
+        local handlebool="$1"
+        local logpattern="$2"
+
+        TEST $GFS --volfile-id=$V0 --volfile-server=$H0 --fuse-flush-handle-interrupt=$handlebool --log-level=DEBUG $M0
+
+        # If the test helper fails (which is considered a setup error, not failure of the test
+        # case itself), kill will be invoked without argument, and that will be the actual
+        # error which is caught.
+        TEST "./$(dirname $0)/open_and_sleep $M0/testfile | { sleep 0.1; xargs -n1 kill -INT; }"
+
+        TEST "grep -E '$logpattern' $log_file"
+        # Basic sanity check, making sure filesystem has not crashed.
+        TEST test -f $M0/testfile
+}
+
+# Theoretically FLUSH might finish before INTERRUPT is handled,
+# in which case we'd get the "no handler found" message (but it's unlikely).
+test_interrupt yes 'FLUSH.*interrupt handler triggered|INTERRUPT.*no handler found'
+EXPECT_WITHIN $UMOUNT_TIMEOUT "Y" force_umount $M0
+test_interrupt no 'INTERRUPT.*no handler found'
+
+## Finish up
+TEST $CLI volume stop $V0;
+EXPECT 'Stopped' volinfo_field $V0 'Status';
+
+TEST $CLI volume delete $V0;
+TEST ! $CLI volume info $V0;
+
+cleanup_tester $(dirname $0)/open_and_sleep;
+cleanup;
diff --git a/tests/features/open_and_sleep.c b/tests/features/open_and_sleep.c
new file mode 100644
index 00000000000..7d0e22a2503
--- /dev/null
+++ b/tests/features/open_and_sleep.c
@@ -0,0 +1,27 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <fcntl.h>
+
+int
+main(int argc, char **argv)
+{
+    pid_t pid;
+    int fd;
+
+    if (argc >= 2) {
+        fd = open(argv[1], O_RDWR | O_CREAT, 0644);
+        if (fd == -1) {
+            fprintf(stderr, "cannot open/create %s\n", argv[1]);
+            return 1;
+        }
+    }
+
+    pid = getpid();
+    printf("%d\n", pid);
+    fflush(stdout);
+
+    for (;;)
+        sleep(1);
+
+    return 0;
+}