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-rw-r--r--source3/lib/g_lock.c139
1 files changed, 101 insertions, 38 deletions
diff --git a/source3/lib/g_lock.c b/source3/lib/g_lock.c
index 0eae3f2131..8a44b22e11 100644
--- a/source3/lib/g_lock.c
+++ b/source3/lib/g_lock.c
@@ -266,7 +266,9 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
struct tevent_timer *te = NULL;
NTSTATUS status;
bool retry = false;
- bool timedout = false;
+ struct timeval timeout_end;
+ struct timeval timeout_remaining;
+ struct timeval time_now;
DEBUG(10, ("Trying to acquire lock %d for %s\n", (int)lock_type,
name));
@@ -295,52 +297,113 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
nt_errstr(status)));
return status;
}
-again:
- retry = false;
- status = g_lock_trylock(ctx, name, lock_type);
- if (NT_STATUS_IS_OK(status)) {
- DEBUG(10, ("Got lock %s\n", name));
- goto done;
- }
- if (!NT_STATUS_EQUAL(status, STATUS_PENDING)) {
- DEBUG(10, ("g_lock_trylock failed: %s\n",
- nt_errstr(status)));
- goto done;
- }
-
- DEBUG(10, ("g_lock_trylock: Did not get lock, waiting...\n"));
-
- if (te == NULL) {
- te = tevent_add_timer(
- ctx->msg->event_ctx, talloc_tos(),
- timeval_current_ofs(timeout.tv_sec, timeout.tv_usec),
- g_lock_timedout, &timedout);
- if (te == NULL) {
- DEBUG(10, ("tevent_add_timer failed\n"));
- status = NT_STATUS_NO_MEMORY;
- goto done;
- }
- }
+ time_now = timeval_current();
+ timeout_end = timeval_sum(&time_now, &timeout);
while (true) {
- if (tevent_loop_once(ctx->msg->event_ctx) == -1) {
- DEBUG(1, ("tevent_loop_once failed\n"));
- status = NT_STATUS_INTERNAL_ERROR;
- goto done;
+ fd_set _r_fds;
+ fd_set *r_fds = NULL;
+ int max_fd = 0;
+ int ret;
+
+ status = g_lock_trylock(ctx, name, lock_type);
+ if (NT_STATUS_IS_OK(status)) {
+ DEBUG(10, ("Got lock %s\n", name));
+ break;
+ }
+ if (!NT_STATUS_EQUAL(status, STATUS_PENDING)) {
+ DEBUG(10, ("g_lock_trylock failed: %s\n",
+ nt_errstr(status)));
+ break;
}
- if (retry) {
- goto again;
+
+ DEBUG(10, ("g_lock_trylock: Did not get lock, waiting...\n"));
+
+ /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * !!! HACK ALERT --- FIX ME !!!
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * What we really want to do here is to react to
+ * MSG_DBWRAP_G_LOCK_RETRY messages that are either sent
+ * by a client doing g_lock_unlock or by ourselves when
+ * we receive a CTDB_SRVID_SAMBA_NOTIFY or
+ * CTDB_SRVID_RECONFIGURE message from ctdbd, i.e. when
+ * either a client holding a lock or a complete node
+ * has died.
+ *
+ * Doing this properly involves calling tevent_loop_once(),
+ * but doing this here with the main ctdbd messaging context
+ * creates a nested event loop when g_lock_lock() is called
+ * from the main event loop, e.g. in a tcon_and_X where the
+ * share_info.tdb needs to be initialized and is locked by
+ * another process, or when the remore registry is accessed
+ * for writing and some other process already holds a lock
+ * on the registry.tdb.
+ *
+ * So as a quick fix, we act a little corasely here: we do
+ * a select on the ctdb connection fd and when it is readable
+ * or we get EINTR, then we retry without actually parsing
+ * any ctdb packages or dispatching messages. This means that
+ * we retry more often than intended by design, but this does
+ * not harm and it is unobtrusive. When we have finished,
+ * the main loop will pick up all the messages and ctdb
+ * packets. The only extra twist is that we cannot use timed
+ * events here but have to handcode a timeout.
+ */
+
+#ifdef CLUSTER_SUPPORT
+ if (lp_clustering()) {
+ struct ctdbd_connection *conn = messaging_ctdbd_connection();
+
+ r_fds = &_r_fds;
+ FD_ZERO(r_fds);
+ max_fd = ctdbd_conn_get_fd(conn);
+ FD_SET(max_fd, r_fds);
}
- if (timedout) {
- DEBUG(10, ("g_lock_lock timed out\n"));
+#endif
- te = NULL;
+ time_now = timeval_current();
+ timeout_remaining = timeval_until(&time_now, &timeout_end);
- status = NT_STATUS_LOCK_NOT_GRANTED;
- goto done;
+ ret = sys_select(max_fd + 1, r_fds, NULL, NULL,
+ &timeout_remaining);
+
+ if (ret == -1) {
+ if (errno != EINTR) {
+ DEBUG(1, ("error calling select: %s\n",
+ strerror(errno)));
+ status = NT_STATUS_INTERNAL_ERROR;
+ break;
+ }
+ /*
+ * errno == EINTR:
+ * This means a signal was received.
+ * It might have been a MSG_DBWRAP_G_LOCK_RETRY message.
+ * ==> retry
+ */
+ } else if (ret == 0) {
+ if (timeval_expired(&timeout_end)) {
+ DEBUG(10, ("g_lock_lock timed out\n"));
+ status = NT_STATUS_LOCK_NOT_GRANTED;
+ break;
+ } else {
+ DEBUG(10, ("select returned 0 but timeout not "
+ "not expired: strange - retrying\n"));
+ }
+ } else if (ret != 1) {
+ DEBUG(1, ("invalid return code of select: %d\n", ret));
+ status = NT_STATUS_INTERNAL_ERROR;
+ break;
}
+ /*
+ * ret == 1:
+ * This means ctdbd has sent us some data.
+ * Might be a CTDB_SRVID_RECONFIGURE or a
+ * CTDB_SRVID_SAMBA_NOTIFY message.
+ * ==> retry
+ */
}
+
done:
if (!NT_STATUS_IS_OK(status)) {