locking: Add io_timeout to sanlock

https://bugzilla.redhat.com/show_bug.cgi?id=1251190

So, if domain loses access to storage, sanlock tries to kill it
after some timeout. So far, the default is 80 seconds. But for
some scenarios this might not be enough. We should allow users to
adjust the timeout according to their needs.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

m4/virt-sanlock.m4

@@ -46,6 +46,13 @@ AC_DEFUN([LIBVIRT_CHECK_SANLOCK],[
         [whether sanlock supports sanlock_inq_lockspace])
     fi
 
+    AC_CHECK_LIB([sanlock_client], [sanlock_add_lockspace_timeout],
+                 [sanlock_add_lockspace_timeout=yes], [sanlock_add_lockspace_timeout=no])
+    if test "x$sanlock_add_lockspace_timeout" = "xyes" ; then
+      AC_DEFINE_UNQUOTED([HAVE_SANLOCK_ADD_LOCKSPACE_TIMEOUT], 1,
+        [whether Sanlock supports sanlock_add_lockspace_timeout])
+    fi
+
     CPPFLAGS="$old_cppflags"
     LIBS="$old_libs"
   fi

src/locking/libvirt_sanlock.aug

@@ -22,6 +22,7 @@ module Libvirt_sanlock =
              | int_entry "host_id"
              | bool_entry "require_lease_for_disks"
              | bool_entry "ignore_readonly_and_shared_disks"
+             | int_entry "io_timeout"
              | str_entry "user"
              | str_entry "group"
    let comment = [ label "#comment" . del /#[ \t]*/ "# " .  store /([^ \t\n][^\n]*)?/ . del /\n/ "\n" ]

src/locking/lock_driver_sanlock.c

@@ -73,6 +73,7 @@ struct _virLockManagerSanlockDriver {
     int hostID;
     bool autoDiskLease;
     char *autoDiskLeasePath;
+    unsigned int io_timeout;
 
     /* under which permissions does sanlock run */
     uid_t user;
@@ -151,6 +152,10 @@ static int virLockManagerSanlockLoadConfig(const char *configFile)
     else
         driver->requireLeaseForDisks = !driver->autoDiskLease;
 
+    p = virConfGetValue(conf, "io_timeout");
+    CHECK_TYPE("io_timeout", VIR_CONF_ULONG);
+    if (p) driver->io_timeout = p->l;
+
     p = virConfGetValue(conf, "user");
     CHECK_TYPE("user", VIR_CONF_STRING);
     if (p) {
@@ -338,7 +343,17 @@ static int virLockManagerSanlockSetupLockspace(void)
      * or we can fallback to polling.
      */
  retry:
-    if ((rv = sanlock_add_lockspace(&ls, 0)) < 0) {
+#ifdef HAVE_SANLOCK_ADD_LOCKSPACE_TIMEOUT
+    rv = sanlock_add_lockspace_timeout(&ls, 0, driver->io_timeout);
+#else
+    if (driver->io_timeout) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("unable to use io_timeout with this version of sanlock"));
+        goto error;
+    }
+    rv = sanlock_add_lockspace(&ls, 0);
+#endif
+    if (rv < 0) {
         if (-rv == EINPROGRESS && --retries) {
 #ifdef HAVE_SANLOCK_INQ_LOCKSPACE
             /* we have this function which blocks until lockspace change the
@@ -404,6 +419,7 @@ static int virLockManagerSanlockInit(unsigned int version,
     driver->requireLeaseForDisks = true;
     driver->hostID = 0;
     driver->autoDiskLease = false;
+    driver->io_timeout = 0;
     driver->user = (uid_t) -1;
     driver->group = (gid_t) -1;
     if (VIR_STRDUP(driver->autoDiskLeasePath, LOCALSTATEDIR "/lib/libvirt/sanlock") < 0) {

src/locking/sanlock.conf

@@ -53,6 +53,13 @@
 #
 #require_lease_for_disks = 1
 
+#
+# Sanlock is able to kill qemu processes on IO timeout. By its internal
+# implementation, the current default is 80 seconds. If you need to adjust
+# the value change the following variable. Value of zero means use the
+# default sanlock timeout.
+#io_timeout = 0
+
 #
 # The combination of user and group under which the sanlock
 # daemon runs. Libvirt will chown created files (like

src/locking/test_libvirt_sanlock.aug.in

@@ -6,5 +6,6 @@ module Test_libvirt_sanlock =
 { "disk_lease_dir" = "/var/lib/libvirt/sanlock" }
 { "host_id" = "1" }
 { "require_lease_for_disks" = "1" }
+{ "io_timeout" = "0" }
 { "user" = "root" }
 { "group" = "root" }