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/*
* Copyright (C) 2001 Sistina Software (UK) Limited.
*
* This file is released under the LGPL.
*
*/
#include "lib.h"
#include "locking.h"
#include "locking_types.h"
#include "lvm-string.h"
#include "activate.h"
#include "toolcontext.h"
#include <signal.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <limits.h>
static struct locking_type _locking;
static sigset_t _oldset;
static int _lock_count = 0; /* Number of locks held */
static int _write_lock_held = 0;
static int _signals_blocked = 0;
static void _block_signals(int flags)
{
sigset_t set;
/* Stop process memory getting swapped out */
#ifdef MCL_CURRENT
if (!_write_lock_held && (flags & LCK_SCOPE_MASK) == LCK_LV &&
(flags & LCK_TYPE_MASK) == LCK_WRITE) {
if (mlockall(MCL_CURRENT | MCL_FUTURE))
log_sys_error("mlockall", "");
else {
log_very_verbose("Locking memory");
_write_lock_held = 1;
}
}
#endif
if (_signals_blocked)
return;
if (sigfillset(&set)) {
log_sys_error("sigfillset", "_block_signals");
return;
}
if (sigprocmask(SIG_SETMASK, &set, &_oldset)) {
log_sys_error("sigprocmask", "_block_signals");
return;
}
_signals_blocked = 1;
return;
}
static void _unblock_signals(void)
{
#ifdef MCL_CURRENT
if (!_lock_count && _write_lock_held) {
if (munlockall()) {
log_very_verbose("Unlocking memory");
log_sys_error("munlockall", "");
}
_write_lock_held = 0;
}
#endif
/* Don't unblock signals while any locks are held */
if (!_signals_blocked || _lock_count)
return;
if (sigprocmask(SIG_SETMASK, &_oldset, NULL)) {
log_sys_error("sigprocmask", "_block_signals");
return;
}
_signals_blocked = 0;
return;
}
static inline void _update_lock_count(int flags)
{
if ((flags & LCK_TYPE_MASK) == LCK_UNLOCK)
_lock_count--;
else
_lock_count++;
}
/*
* Select a locking type
*/
int init_locking(int type, struct config_tree *cf)
{
switch (type) {
case 0:
init_no_locking(&_locking, cf);
log_print("WARNING: Locking disabled. Be careful! "
"This could corrupt your metadata.");
return 1;
case 1:
if (!init_file_locking(&_locking, cf))
break;
log_very_verbose("File-based locking enabled.");
return 1;
#ifdef HAVE_LIBDL
case 2:
if (!init_external_locking(&_locking, cf))
break;
log_very_verbose("External locking enabled.");
return 1;
#endif
default:
log_error("Unknown locking type requested.");
return 0;
}
if (!ignorelockingfailure())
return 0;
/* FIXME Ensure only read ops are permitted */
log_verbose("Locking disabled - only read operations permitted.");
init_no_locking(&_locking, cf);
return 1;
}
void fin_locking(void)
{
_locking.fin_locking();
}
/*
* Does the LVM1 driver know of this VG name?
*/
int check_lvm1_vg_inactive(struct cmd_context *cmd, const char *vgname)
{
struct stat info;
char path[PATH_MAX];
/* We'll allow operations on orphans */
if (!*vgname)
return 1;
if (lvm_snprintf(path, sizeof(path), "%s/lvm/VGs/%s", cmd->proc_dir,
vgname) < 0) {
log_error("LVM1 proc VG pathname too long for %s", vgname);
return 0;
}
if (stat(path, &info) == 0) {
log_error("%s exists: Is the original LVM driver using "
"this volume group?", path);
return 0;
} else if (errno != ENOENT && errno != ENOTDIR) {
log_sys_error("stat", path);
return 0;
}
return 1;
}
/*
* VG locking is by VG name.
* FIXME This should become VG uuid.
*/
static int _lock_vol(struct cmd_context *cmd, const char *resource, int flags)
{
_block_signals(flags);
if (!(_locking.lock_resource(cmd, resource, flags))) {
_unblock_signals();
return 0;
}
_update_lock_count(flags);
_unblock_signals();
return 1;
}
int lock_vol(struct cmd_context *cmd, const char *vol, int flags)
{
char resource[258];
switch (flags & LCK_SCOPE_MASK) {
case LCK_VG:
/* Lock VG to change on-disk metadata. */
/* If LVM1 driver knows about the VG, it can't be accessed. */
if (!check_lvm1_vg_inactive(cmd, vol))
return 0;
case LCK_LV:
/* Suspend LV if it's active. */
strncpy(resource, vol, sizeof(resource));
break;
default:
log_error("Unrecognised lock scope: %d",
flags & LCK_SCOPE_MASK);
return 0;
}
if (!_lock_vol(cmd, resource, flags))
return 0;
/* Perform immediate unlock unless LCK_HOLD set */
if (!(flags & LCK_HOLD) && ((flags & LCK_TYPE_MASK) != LCK_UNLOCK)) {
if (!_lock_vol(cmd, resource,
(flags & ~LCK_TYPE_MASK) | LCK_UNLOCK))
return 0;
}
return 1;
}
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