mirror of
https://github.com/samba-team/samba.git
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d7c00d8d7e
(This used to be ctdb commit eae1d4f9e52e73b4d8769868fffdafa590d03784)
168 lines
4.5 KiB
C
168 lines
4.5 KiB
C
/*
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wait for a tdb chain lock
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Copyright (C) Andrew Tridgell 2006
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "includes.h"
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#include "lib/events/events.h"
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#include "system/filesys.h"
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#include "system/wait.h"
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#include "db_wrap.h"
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#include "lib/tdb/include/tdb.h"
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#include "../include/ctdb_private.h"
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struct lockwait_handle {
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struct ctdb_context *ctdb;
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struct ctdb_db_context *ctdb_db;
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struct fd_event *fde;
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int fd[2];
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pid_t child;
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void *private_data;
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void (*callback)(void *);
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TDB_DATA key;
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struct timeval start_time;
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};
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static void lockwait_handler(struct event_context *ev, struct fd_event *fde,
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uint16_t flags, void *private_data)
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{
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struct lockwait_handle *h = talloc_get_type(private_data,
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struct lockwait_handle);
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void (*callback)(void *) = h->callback;
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void *p = h->private_data;
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pid_t child = h->child;
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TDB_DATA key = h->key;
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struct tdb_context *tdb = h->ctdb_db->ltdb->tdb;
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TALLOC_CTX *tmp_ctx = talloc_new(ev);
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key.dptr = talloc_memdup(tmp_ctx, key.dptr, key.dsize);
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talloc_set_destructor(h, NULL);
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ctdb_latency(h->ctdb_db, "lockwait", &h->ctdb->statistics.max_lockwait_latency, h->start_time);
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h->ctdb->statistics.pending_lockwait_calls--;
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/* the handle needs to go away when the context is gone - when
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the handle goes away this implicitly closes the pipe, which
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kills the child holding the lock */
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talloc_steal(tmp_ctx, h);
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if (h->ctdb->flags & CTDB_FLAG_TORTURE) {
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if (tdb_chainlock_nonblock(tdb, key) == 0) {
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ctdb_fatal(h->ctdb, "got chain lock while lockwait child active");
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}
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}
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tdb_chainlock_mark(tdb, key);
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callback(p);
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tdb_chainlock_unmark(tdb, key);
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kill(child, SIGKILL);
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talloc_free(tmp_ctx);
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}
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static int lockwait_destructor(struct lockwait_handle *h)
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{
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h->ctdb->statistics.pending_lockwait_calls--;
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kill(h->child, SIGKILL);
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return 0;
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}
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/*
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setup a non-blocking chainlock on a tdb record. If this function
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returns NULL then it could not get the chainlock. Otherwise it
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returns a opaque handle, and will call callback() once it has
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managed to get the chainlock. You can cancel it by using talloc_free
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on the returned handle.
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It is the callers responsibility to unlock the chainlock once
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acquired
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*/
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struct lockwait_handle *ctdb_lockwait(struct ctdb_db_context *ctdb_db,
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TDB_DATA key,
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void (*callback)(void *private_data),
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void *private_data)
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{
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struct lockwait_handle *result;
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int ret;
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pid_t parent = getpid();
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ctdb_db->ctdb->statistics.lockwait_calls++;
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ctdb_db->ctdb->statistics.pending_lockwait_calls++;
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if (!(result = talloc_zero(private_data, struct lockwait_handle))) {
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ctdb_db->ctdb->statistics.pending_lockwait_calls--;
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return NULL;
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}
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ret = pipe(result->fd);
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if (ret != 0) {
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talloc_free(result);
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ctdb_db->ctdb->statistics.pending_lockwait_calls--;
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return NULL;
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}
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result->child = fork();
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if (result->child == (pid_t)-1) {
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close(result->fd[0]);
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close(result->fd[1]);
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talloc_free(result);
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ctdb_db->ctdb->statistics.pending_lockwait_calls--;
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return NULL;
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}
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result->callback = callback;
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result->private_data = private_data;
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result->ctdb = ctdb_db->ctdb;
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result->ctdb_db = ctdb_db;
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result->key = key;
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if (result->child == 0) {
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char c = 0;
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close(result->fd[0]);
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tdb_chainlock(ctdb_db->ltdb->tdb, key);
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write(result->fd[1], &c, 1);
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/* make sure we die when our parent dies */
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while (kill(parent, 0) == 0 || errno != ESRCH) {
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sleep(5);
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}
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_exit(0);
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}
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close(result->fd[1]);
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set_close_on_exec(result->fd[0]);
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DEBUG(DEBUG_DEBUG, (__location__ " Created PIPE FD:%d to child lockwait process\n", result->fd[0]));
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talloc_set_destructor(result, lockwait_destructor);
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result->fde = event_add_fd(ctdb_db->ctdb->ev, result, result->fd[0],
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EVENT_FD_READ|EVENT_FD_AUTOCLOSE, lockwait_handler,
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(void *)result);
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if (result->fde == NULL) {
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talloc_free(result);
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ctdb_db->ctdb->statistics.pending_lockwait_calls--;
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return NULL;
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}
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result->start_time = timeval_current();
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return result;
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}
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