mirror of
git://sourceware.org/git/lvm2.git
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305 lines
6.4 KiB
C
305 lines
6.4 KiB
C
/*
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* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
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* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
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*
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* This file is part of LVM2.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License v.2.
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*
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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, write to the Free Software Foundation,
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* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "lib.h"
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#include "locking.h"
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#include "locking_types.h"
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#include "activate.h"
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#include "config.h"
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#include "defaults.h"
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#include "lvm-file.h"
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#include "lvm-string.h"
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#include "lvmcache.h"
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#include <limits.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/file.h>
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#include <fcntl.h>
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#include <signal.h>
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struct lock_list {
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struct list list;
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int lf;
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char *res;
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};
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static struct list _lock_list;
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static char _lock_dir[NAME_LEN];
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static sig_t _oldhandler;
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static sigset_t _fullsigset, _intsigset;
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static volatile sig_atomic_t _handler_installed;
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static int _release_lock(const char *file, int unlock)
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{
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struct lock_list *ll;
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struct list *llh, *llt;
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struct stat buf1, buf2;
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list_iterate_safe(llh, llt, &_lock_list) {
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ll = list_item(llh, struct lock_list);
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if (!file || !strcmp(ll->res, file)) {
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list_del(llh);
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if (unlock) {
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log_very_verbose("Unlocking %s", ll->res);
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if (flock(ll->lf, LOCK_NB | LOCK_UN))
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log_sys_error("flock", ll->res);
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}
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if (!flock(ll->lf, LOCK_NB | LOCK_EX) &&
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!stat(ll->res, &buf1) &&
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!fstat(ll->lf, &buf2) &&
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!memcmp(&buf1.st_ino, &buf2.st_ino, sizeof(ino_t)))
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if (unlink(ll->res))
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log_sys_error("unlink", ll->res);
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if (close(ll->lf) < 0)
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log_sys_error("close", ll->res);
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dbg_free(ll->res);
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dbg_free(llh);
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if (file)
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return 1;
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}
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}
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return 0;
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}
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static void _fin_file_locking(void)
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{
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_release_lock(NULL, 1);
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}
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static void _reset_file_locking(void)
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{
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_release_lock(NULL, 0);
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}
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static void _remove_ctrl_c_handler()
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{
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siginterrupt(SIGINT, 0);
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if (!_handler_installed)
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return;
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_handler_installed = 0;
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sigprocmask(SIG_SETMASK, &_fullsigset, NULL);
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if (signal(SIGINT, _oldhandler) == SIG_ERR)
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log_sys_error("signal", "_remove_ctrl_c_handler");
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}
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static void _trap_ctrl_c(int sig)
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{
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_remove_ctrl_c_handler();
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log_error("CTRL-c detected: giving up waiting for lock");
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}
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static void _install_ctrl_c_handler()
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{
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_handler_installed = 1;
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if ((_oldhandler = signal(SIGINT, _trap_ctrl_c)) == SIG_ERR) {
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_handler_installed = 0;
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return;
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}
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sigprocmask(SIG_SETMASK, &_intsigset, NULL);
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siginterrupt(SIGINT, 1);
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}
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static int _lock_file(const char *file, int flags)
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{
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int operation;
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int r = 1;
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int old_errno;
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struct lock_list *ll;
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struct stat buf1, buf2;
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char state;
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switch (flags & LCK_TYPE_MASK) {
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case LCK_READ:
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operation = LOCK_SH;
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state = 'R';
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break;
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case LCK_WRITE:
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operation = LOCK_EX;
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state = 'W';
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break;
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case LCK_UNLOCK:
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return _release_lock(file, 1);
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default:
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log_error("Unrecognised lock type: %d", flags & LCK_TYPE_MASK);
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return 0;
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}
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if (!(ll = dbg_malloc(sizeof(struct lock_list))))
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return 0;
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if (!(ll->res = dbg_strdup(file))) {
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dbg_free(ll);
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return 0;
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}
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ll->lf = -1;
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log_very_verbose("Locking %s %c%c", ll->res, state,
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flags & LCK_NONBLOCK ? ' ' : 'B');
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do {
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if (ll->lf > -1)
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close(ll->lf);
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if ((ll->lf = open(file, O_CREAT | O_APPEND | O_RDWR, 0777))
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< 0) {
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log_sys_error("open", file);
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goto err;
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}
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if ((flags & LCK_NONBLOCK))
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operation |= LOCK_NB;
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else
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_install_ctrl_c_handler();
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r = flock(ll->lf, operation);
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old_errno = errno;
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if (!(flags & LCK_NONBLOCK))
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_remove_ctrl_c_handler();
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if (r) {
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errno = old_errno;
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log_sys_error("flock", ll->res);
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goto err;
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}
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if (!stat(ll->res, &buf1) && !fstat(ll->lf, &buf2) &&
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!memcmp(&buf1.st_ino, &buf2.st_ino, sizeof(ino_t)))
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break;
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} while (!(flags & LCK_NONBLOCK));
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list_add(&_lock_list, &ll->list);
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return 1;
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err:
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dbg_free(ll->res);
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dbg_free(ll);
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return 0;
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}
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static int _file_lock_resource(struct cmd_context *cmd, const char *resource,
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int flags)
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{
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char lockfile[PATH_MAX];
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switch (flags & LCK_SCOPE_MASK) {
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case LCK_VG:
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if (!resource || !*resource)
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lvm_snprintf(lockfile, sizeof(lockfile),
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"%s/P_orphans", _lock_dir);
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else
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lvm_snprintf(lockfile, sizeof(lockfile),
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"%s/V_%s", _lock_dir, resource);
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if (!_lock_file(lockfile, flags))
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return 0;
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switch (flags & LCK_TYPE_MASK) {
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case LCK_UNLOCK:
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lvmcache_unlock_vgname(resource);
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break;
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default:
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lvmcache_lock_vgname(resource,
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(flags & LCK_TYPE_MASK) ==
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LCK_READ);
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}
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break;
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case LCK_LV:
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switch (flags & LCK_TYPE_MASK) {
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case LCK_UNLOCK:
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log_debug("Unlocking LV %s", resource);
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if (!lv_resume_if_active(cmd, resource))
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return 0;
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break;
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case LCK_NULL:
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log_debug("Locking LV %s (NL)", resource);
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if (!lv_deactivate(cmd, resource))
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return 0;
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break;
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case LCK_READ:
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log_debug("Locking LV %s (R)", resource);
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if (!lv_activate_with_filter(cmd, resource))
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return 0;
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break;
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case LCK_WRITE:
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log_debug("Locking LV %s (W)", resource);
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if (!lv_suspend_if_active(cmd, resource))
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return 0;
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break;
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case LCK_EXCL:
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log_debug("Locking LV %s (EX)", resource);
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if (!lv_activate_with_filter(cmd, resource))
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return 0;
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break;
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default:
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break;
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}
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break;
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default:
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log_error("Unrecognised lock scope: %d",
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flags & LCK_SCOPE_MASK);
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return 0;
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}
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return 1;
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}
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int init_file_locking(struct locking_type *locking, struct config_tree *cft)
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{
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locking->lock_resource = _file_lock_resource;
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locking->reset_locking = _reset_file_locking;
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locking->fin_locking = _fin_file_locking;
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locking->flags = 0;
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/* Get lockfile directory from config file */
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strncpy(_lock_dir, find_config_str(cft->root, "global/locking_dir",
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DEFAULT_LOCK_DIR),
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sizeof(_lock_dir));
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if (!create_dir(_lock_dir))
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return 0;
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/* Trap a read-only file system */
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if ((access(_lock_dir, R_OK | W_OK | X_OK) == -1) && (errno == EROFS))
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return 0;
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list_init(&_lock_list);
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if (sigfillset(&_intsigset) || sigfillset(&_fullsigset)) {
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log_sys_error("sigfillset", "init_file_locking");
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return 0;
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}
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if (sigdelset(&_intsigset, SIGINT)) {
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log_sys_error("sigdelset", "init_file_locking");
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return 0;
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}
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return 1;
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}
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