+++ /dev/null
-/*
- ctdb freeze handling
-
- Copyright (C) Andrew Tridgell 2007
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; if not, see <http://www.gnu.org/licenses/>.
-*/
-#include "includes.h"
-#include "lib/events/events.h"
-#include "../tdb/include/tdb.h"
-#include "system/network.h"
-#include "system/filesys.h"
-#include "system/wait.h"
-#include "../include/ctdb_private.h"
-#include "lib/util/dlinklist.h"
-
-
-/*
- lock all databases
- */
-static int ctdb_lock_all_databases(struct ctdb_context *ctdb)
-{
- struct ctdb_db_context *ctdb_db;
- for (ctdb_db=ctdb->db_list;ctdb_db;ctdb_db=ctdb_db->next) {
- if (tdb_lockall(ctdb_db->ltdb->tdb) != 0) {
- return -1;
- }
- }
- return 0;
-}
-
-/*
- a list of control requests waiting for a freeze lock child to get
- the database locks
- */
-struct ctdb_freeze_waiter {
- struct ctdb_freeze_waiter *next, *prev;
- struct ctdb_context *ctdb;
- struct ctdb_req_control *c;
- int32_t status;
-};
-
-/* a handle to a freeze lock child process */
-struct ctdb_freeze_handle {
- struct ctdb_context *ctdb;
- pid_t child;
- int fd;
- struct ctdb_freeze_waiter *waiters;
-};
-
-/*
- destroy a freeze handle
- */
-static int ctdb_freeze_handle_destructor(struct ctdb_freeze_handle *h)
-{
- h->ctdb->freeze_mode = CTDB_FREEZE_NONE;
- kill(h->child, SIGKILL);
- waitpid(h->child, NULL, 0);
- return 0;
-}
-
-/*
- called when the child writes its status to us
- */
-static void ctdb_freeze_lock_handler(struct event_context *ev, struct fd_event *fde,
- uint16_t flags, void *private_data)
-{
- struct ctdb_freeze_handle *h = talloc_get_type(private_data, struct ctdb_freeze_handle);
- int32_t status;
- struct ctdb_freeze_waiter *w;
-
- if (h->ctdb->freeze_mode == CTDB_FREEZE_FROZEN) {
- DEBUG(0,("freeze child died - unfreezing\n"));
- talloc_free(h);
- return;
- }
-
- if (read(h->fd, &status, sizeof(status)) != sizeof(status)) {
- DEBUG(0,("read error from freeze lock child\n"));
- status = -1;
- }
-
- if (status == -1) {
- DEBUG(0,("Failed to get locks in ctdb_freeze_child\n"));
- /* we didn't get the locks - destroy the handle */
- talloc_free(h);
- return;
- }
-
- h->ctdb->freeze_mode = CTDB_FREEZE_FROZEN;
-
- /* notify the waiters */
- while ((w = h->ctdb->freeze_handle->waiters)) {
- w->status = status;
- DLIST_REMOVE(h->ctdb->freeze_handle->waiters, w);
- talloc_free(w);
- }
-}
-
-/*
- create a child which gets locks on all the open databases, then calls the callback telling the parent
- that it is done
- */
-static struct ctdb_freeze_handle *ctdb_freeze_lock(struct ctdb_context *ctdb)
-{
- struct ctdb_freeze_handle *h;
- int fd[2];
- struct fd_event *fde;
-
- h = talloc_zero(ctdb, struct ctdb_freeze_handle);
- CTDB_NO_MEMORY_VOID(ctdb, h);
-
- h->ctdb = ctdb;
-
- /* use socketpair() instead of pipe() so we have bi-directional fds */
- if (socketpair(AF_UNIX, SOCK_STREAM, 0, fd) != 0) {
- DEBUG(0,("Failed to create pipe for ctdb_freeze_lock\n"));
- talloc_free(h);
- return NULL;
- }
-
- h->child = fork();
- if (h->child == -1) {
- DEBUG(0,("Failed to fork child for ctdb_freeze_lock\n"));
- talloc_free(h);
- return NULL;
- }
-
- if (h->child == 0) {
- int ret;
- /* in the child */
- close(fd[0]);
- ret = ctdb_lock_all_databases(ctdb);
- if (ret != 0) {
- _exit(0);
- }
- write(fd[1], &ret, sizeof(ret));
- /* the read here means we will die if the parent exits */
- read(fd[1], &ret, sizeof(ret));
- _exit(0);
- }
-
- talloc_set_destructor(h, ctdb_freeze_handle_destructor);
-
- close(fd[1]);
-
- h->fd = fd[0];
-
- fde = event_add_fd(ctdb->ev, h, h->fd, EVENT_FD_READ|EVENT_FD_AUTOCLOSE,
- ctdb_freeze_lock_handler, h);
- if (fde == NULL) {
- DEBUG(0,("Failed to setup fd event for ctdb_freeze_lock\n"));
- close(fd[0]);
- talloc_free(h);
- return NULL;
- }
-
- return h;
-}
-
-/*
- destroy a waiter for a freeze mode change
- */
-static int ctdb_freeze_waiter_destructor(struct ctdb_freeze_waiter *w)
-{
- DLIST_REMOVE(w->ctdb->freeze_handle->waiters, w);
- ctdb_request_control_reply(w->ctdb, w->c, NULL, w->status, NULL);
- return 0;
-}
-
-/*
- start the freeze process
- */
-void ctdb_start_freeze(struct ctdb_context *ctdb)
-{
- if (ctdb->freeze_mode == CTDB_FREEZE_FROZEN) {
- /* we're already frozen */
- return;
- }
-
- /* if there isn't a freeze lock child then create one */
- if (!ctdb->freeze_handle) {
- ctdb->freeze_handle = ctdb_freeze_lock(ctdb);
- CTDB_NO_MEMORY_VOID(ctdb, ctdb->freeze_handle);
- ctdb->freeze_mode = CTDB_FREEZE_PENDING;
- }
-}
-
-/*
- freeze the databases
- */
-int32_t ctdb_control_freeze(struct ctdb_context *ctdb, struct ctdb_req_control *c, bool *async_reply)
-{
- struct ctdb_freeze_waiter *w;
-
- if (ctdb->freeze_mode == CTDB_FREEZE_FROZEN) {
- /* we're already frozen */
- return 0;
- }
-
- ctdb_start_freeze(ctdb);
-
- /* add ourselves to list of waiters */
- w = talloc(ctdb->freeze_handle, struct ctdb_freeze_waiter);
- CTDB_NO_MEMORY(ctdb, w);
- w->ctdb = ctdb;
- w->c = talloc_steal(w, c);
- w->status = -1;
- talloc_set_destructor(w, ctdb_freeze_waiter_destructor);
- DLIST_ADD(ctdb->freeze_handle->waiters, w);
-
- /* we won't reply till later */
- *async_reply = True;
- return 0;
-}
-
-
-/*
- block until we are frozen, used during daemon startup
- */
-bool ctdb_blocking_freeze(struct ctdb_context *ctdb)
-{
- ctdb_start_freeze(ctdb);
-
- /* block until frozen */
- while (ctdb->freeze_mode == CTDB_FREEZE_PENDING) {
- event_loop_once(ctdb->ev);
- }
-
- return ctdb->freeze_mode == CTDB_FREEZE_FROZEN;
-}
-
-
-
-/*
- thaw the databases
- */
-int32_t ctdb_control_thaw(struct ctdb_context *ctdb)
-{
- talloc_free(ctdb->freeze_handle);
- ctdb->freeze_handle = NULL;
- ctdb_call_resend_all(ctdb);
- return 0;
-}
git.samba.org / gd / samba / .git / blobdiff