/*
Unix SMB/CIFS implementation.
trivial database library
Copyright (C) Andrew Tridgell 1999-2005
Copyright (C) Paul `Rusty' Russell 2000
Copyright (C) Jeremy Allison 2000-2003
** NOTE! The following LGPL license applies to the tdb
** library. This does NOT imply that all of Samba is released
** under the LGPL
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "tdb_private.h"
_PUBLIC_ void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
{
tdb->interrupt_sig_ptr = ptr;
}
static int fcntl_lock(struct tdb_context *tdb,
int rw, off_t off, off_t len, bool waitflag)
{
struct flock fl;
int cmd;
#ifdef USE_TDB_MUTEX_LOCKING
{
int ret;
if (tdb_mutex_lock(tdb, rw, off, len, waitflag, &ret)) {
return ret;
}
}
#endif
fl.l_type = rw;
fl.l_whence = SEEK_SET;
fl.l_start = off;
fl.l_len = len;
fl.l_pid = 0;
cmd = waitflag ? F_SETLKW : F_SETLK;
return fcntl(tdb->fd, cmd, &fl);
}
static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
{
struct flock fl;
#if 0 /* Check they matched up locks and unlocks correctly. */
char line[80];
FILE *locks;
bool found = false;
locks = fopen("/proc/locks", "r");
while (fgets(line, 80, locks)) {
char *p;
int type, start, l;
/* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */
p = strchr(line, ':') + 1;
if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY ")))
continue;
p += strlen(" FLOCK ADVISORY ");
if (strncmp(p, "READ ", strlen("READ ")) == 0)
type = F_RDLCK;
else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
type = F_WRLCK;
else
abort();
p += 6;
if (atoi(p) != getpid())
continue;
p = strchr(strchr(p, ' ') + 1, ' ') + 1;
start = atoi(p);
p = strchr(p, ' ') + 1;
if (strncmp(p, "EOF", 3) == 0)
l = 0;
else
l = atoi(p) - start + 1;
if (off == start) {
if (len != l) {
fprintf(stderr, "Len %u should be %u: %s",
(int)len, l, line);
abort();
}
if (type != rw) {
fprintf(stderr, "Type %s wrong: %s",
rw == F_RDLCK ? "READ" : "WRITE", line);
abort();
}
found = true;
break;
}
}
if (!found) {
fprintf(stderr, "Unlock on %u@%u not found!\n",
(int)off, (int)len);
abort();
}
fclose(locks);
#endif
#ifdef USE_TDB_MUTEX_LOCKING
{
int ret;
if (tdb_mutex_unlock(tdb, rw, off, len, &ret)) {
return ret;
}
}
#endif
fl.l_type = F_UNLCK;
fl.l_whence = SEEK_SET;
fl.l_start = off;
fl.l_len = len;
fl.l_pid = 0;
return fcntl(tdb->fd, F_SETLKW, &fl);
}
/*
* Calculate the lock offset for a list
*
* list -1 is the freelist, otherwise a hash chain.
*
* Note that we consistently (but without real reason) lock hash chains at an
* offset that is 4 bytes below the real offset of the corresponding list head
* in the db.
*
* This is the memory layout of the hashchain array:
*
* FREELIST_TOP + 0 = freelist
* FREELIST_TOP + 4 = hashtable list 0
* FREELIST_TOP + 8 = hashtable list 1
* ...
*
* Otoh lock_offset computes:
*
* freelist = FREELIST_TOP - 4
* list 0 = FREELIST_TOP + 0
* list 1 = FREELIST_TOP + 4
* ...
*
* Unfortunately we can't change this calculation in order to align the locking
* offset with the memory layout, as that would make the locking incompatible
* between different tdb versions.
*/
static tdb_off_t lock_offset(int list)
{
return FREELIST_TOP + 4*list;
}
/* a byte range locking function - return 0 on success
this functions locks/unlocks "len" byte at the specified offset.
On error, errno is also set so that errors are passed back properly
through tdb_open().
note that a len of zero means lock to end of file
*/
int tdb_brlock(struct tdb_context *tdb,
int rw_type, tdb_off_t offset, size_t len,
enum tdb_lock_flags flags)
{
int ret;
if (tdb->flags & TDB_NOLOCK) {
return 0;
}
if (flags & TDB_LOCK_MARK_ONLY) {
return 0;
}
if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
tdb->ecode = TDB_ERR_RDONLY;
return -1;
}
do {
ret = fcntl_lock(tdb, rw_type, offset, len,
flags & TDB_LOCK_WAIT);
/* Check for a sigalarm break. */
if (ret == -1 && errno == EINTR &&
tdb->interrupt_sig_ptr &&
*tdb->interrupt_sig_ptr) {
break;
}
} while (ret == -1 && errno == EINTR);
if (ret == -1) {
tdb->ecode = TDB_ERR_LOCK;
/* Generic lock error. errno set by fcntl.
* EAGAIN is an expected return from non-blocking
* locks. */
if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) {
TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %u rw_type=%d flags=%d len=%zu\n",
tdb->fd, offset, rw_type, flags, len));
}
return -1;
}
return 0;
}
int tdb_brunlock(struct tdb_context *tdb,
int rw_type, tdb_off_t offset, size_t len)
{
int ret;
if (tdb->flags & TDB_NOLOCK) {
return 0;
}
do {
ret = fcntl_unlock(tdb, rw_type, offset, len);
} while (ret == -1 && errno == EINTR);
if (ret == -1) {
TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %u rw_type=%u len=%zu\n",
tdb->fd, offset, rw_type, len));
}
return ret;
}
/*
* Do a tdb_brlock in a loop. Some OSes (such as solaris) have too
* conservative deadlock detection and claim a deadlock when progress can be
* made. For those OSes we may loop for a while.
*/
static int tdb_brlock_retry(struct tdb_context *tdb,
int rw_type, tdb_off_t offset, size_t len,
enum tdb_lock_flags flags)
{
int count = 1000;
while (count--) {
struct timeval tv;
int ret;
ret = tdb_brlock(tdb, rw_type, offset, len, flags);
if (ret == 0) {
return 0;
}
if (errno != EDEADLK) {
break;
}
/* sleep for as short a time as we can - more portable than usleep() */
tv.tv_sec = 0;
tv.tv_usec = 1;
select(0, NULL, NULL, NULL, &tv);
}
return -1;
}
/*
upgrade a read lock to a write lock.
*/
int tdb_allrecord_upgrade(struct tdb_context *tdb)
{
int ret;
if (tdb->allrecord_lock.count != 1) {
TDB_LOG((tdb, TDB_DEBUG_ERROR,
"tdb_allrecord_upgrade failed: count %u too high\n",
tdb->allrecord_lock.count));
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (tdb->allrecord_lock.off != 1) {
TDB_LOG((tdb, TDB_DEBUG_ERROR,
"tdb_allrecord_upgrade failed: already upgraded?\n"));
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (tdb_have_mutexes(tdb)) {
ret = tdb_mutex_allrecord_upgrade(tdb);
if (ret == -1) {
goto fail;
}
ret = tdb_brlock_retry(tdb, F_WRLCK, lock_offset(tdb->hash_size),
0, TDB_LOCK_WAIT|TDB_LOCK_PROBE);
if (ret == -1) {
tdb_mutex_allrecord_downgrade(tdb);
}
} else {
ret = tdb_brlock_retry(tdb, F_WRLCK, FREELIST_TOP, 0,
TDB_LOCK_WAIT|TDB_LOCK_PROBE);
}
if (ret == 0) {
tdb->allrecord_lock.ltype = F_WRLCK;
tdb->allrecord_lock.off = 0;
return 0;
}
fail:
TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_allrecord_upgrade failed\n"));
return -1;
}
static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
tdb_off_t offset)
{
int i;
for (i=0; i<tdb->num_lockrecs; i++) {
if (tdb->lockrecs[i].off == offset) {
return &tdb->lockrecs[i];
}
}
return NULL;
}
/* lock an offset in the database. */
int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
enum tdb_lock_flags flags)
{
struct tdb_lock_type *new_lck;
if (offset >= lock_offset(tdb->hash_size)) {
tdb->ecode = TDB_ERR_LOCK;
TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
offset, ltype));
return -1;
}
if (tdb->flags & TDB_NOLOCK)
return 0;
new_lck = find_nestlock(tdb, offset);
if (new_lck) {
if ((new_lck->ltype == F_RDLCK) && (ltype == F_WRLCK)) {
if (!tdb_have_mutexes(tdb)) {
int ret;
/*
* Upgrade the underlying fcntl
* lock. Mutexes don't do readlocks,
* so this only applies to fcntl
* locking.
*/
ret = tdb_brlock(tdb, ltype, offset, 1, flags);
if (ret != 0) {
return ret;
}
}
new_lck->ltype = F_WRLCK;
}
/*
* Just increment the in-memory struct, posix locks
* don't stack.
*/
new_lck->count++;
return 0;
}
if (tdb->num_lockrecs == tdb->lockrecs_array_length) {
new_lck = (struct tdb_lock_type *)realloc(
tdb->lockrecs,
sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1));
if (new_lck == NULL) {
errno = ENOMEM;
return -1;
}
tdb->lockrecs_array_length = tdb->num_lockrecs+1;
tdb->lockrecs = new_lck;
}
/* Since fcntl locks don't nest, we do a lock for the first one,
and simply bump the count for future ones */
if (tdb_brlock(tdb, ltype, offset, 1, flags)) {
return -1;
}
new_lck = &tdb->lockrecs[tdb->num_lockrecs];
new_lck->off = offset;
new_lck->count = 1;
new_lck->ltype = ltype;
tdb->num_lockrecs++;
return 0;
}
static int tdb_lock_and_recover(struct tdb_context *tdb)
{
int ret;
/* We need to match locking order in transaction commit. */
if (tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT)) {
return -1;
}
if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT)) {
tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
return -1;
}
ret = tdb_transaction_recover(tdb);
tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1);
tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
return ret;
}
static bool have_data_locks(const struct tdb_context *tdb)
{
int i;
for (i = 0; i < tdb->num_lockrecs; i++) {
if (tdb->lockrecs[i].off >= lock_offset(-1))
return true;
}
return false;
}
/*
* A allrecord lock allows us to avoid per chain locks. Check if the allrecord
* lock is strong enough.
*/
static int tdb_lock_covered_by_allrecord_lock(struct tdb_context *tdb,
int ltype)
{
if (ltype == F_RDLCK) {
/*
* The allrecord_lock is equal (F_RDLCK) or stronger
* (F_WRLCK). Pass.
*/
return 0;
}
if (tdb->allrecord_lock.ltype == F_RDLCK) {
/*
* We ask for ltype==F_WRLCK, but the allrecord_lock
* is too weak. We can't upgrade here, so fail.
*/
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
/*
* Asking for F_WRLCK, allrecord is F_WRLCK as well. Pass.
*/
return 0;
}
static int tdb_lock_list(struct tdb_context *tdb, int list, int ltype,
enum tdb_lock_flags waitflag)
{
int ret;
bool check = false;
if (tdb->allrecord_lock.count) {
return tdb_lock_covered_by_allrecord_lock(tdb, ltype);
}
/*
* Check for recoveries: Someone might have kill -9'ed a process
* during a commit.
*/
check = !have_data_locks(tdb);
ret = tdb_nest_lock(tdb, lock_offset(list), ltype, waitflag);
if (ret == 0 && check && tdb_needs_recovery(tdb)) {
tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
if (tdb_lock_and_recover(tdb) == -1) {
return -1;
}
return tdb_lock_list(tdb, list, ltype, waitflag);
}
return ret;
}
/* lock a list in the database. list -1 is the alloc list */
int tdb_lock(struct tdb_context *tdb, int list, int ltype)
{
int ret;
ret = tdb_lock_list(tdb, list, ltype, TDB_LOCK_WAIT);
if (ret) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
"ltype=%d (%s)\n", list, ltype, strerror(errno)));
}
return ret;
}
/* lock a list in the database. list -1 is the alloc list. non-blocking lock */
_PUBLIC_ int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
{
return tdb_lock_list(tdb, list, ltype, TDB_LOCK_NOWAIT);
}
int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
bool mark_lock)
{
int ret = -1;
struct tdb_lock_type *lck;
if (tdb->flags & TDB_NOLOCK)
return 0;
/* Sanity checks */
if (offset >= lock_offset(tdb->hash_size)) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->hash_size));
return ret;
}
lck = find_nestlock(tdb, offset);
if ((lck == NULL) || (lck->count == 0)) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
return -1;
}
if (lck->count > 1) {
lck->count--;
return 0;
}
/*
* This lock has count==1 left, so we need to unlock it in the
* kernel. We don't bother with decrementing the in-memory array
* element, we're about to overwrite it with the last array element
* anyway.
*/
if (mark_lock) {
ret = 0;
} else {
ret = tdb_brunlock(tdb, ltype, offset, 1);
}
/*
* Shrink the array by overwriting the element just unlocked with the
* last array element.
*/
*lck = tdb->lockrecs[--tdb->num_lockrecs];
/*
* We don't bother with realloc when the array shrinks, but if we have
* a completely idle tdb we should get rid of the locked array.
*/
if (ret)
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n"));
return ret;
}
_PUBLIC_ int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
{
/* a global lock allows us to avoid per chain locks */
if (tdb->allrecord_lock.count) {
return tdb_lock_covered_by_allrecord_lock(tdb, ltype);
}
return tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
}
/*
get the transaction lock
*/
int tdb_transaction_lock(struct tdb_context *tdb, int ltype,
enum tdb_lock_flags lockflags)
{
return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, lockflags);
}
/*
release the transaction lock
*/
int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
{
return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false);
}
/* Returns 0 if all done, -1 if error, 1 if ok. */
static int tdb_allrecord_check(struct tdb_context *tdb, int ltype,
enum tdb_lock_flags flags, bool upgradable)
{
/* There are no locks on read-only dbs */
if (tdb->read_only || tdb->traverse_read) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (tdb->allrecord_lock.count &&
tdb->allrecord_lock.ltype == (uint32_t)ltype) {
tdb->allrecord_lock.count++;
return 0;
}
if (tdb->allrecord_lock.count) {
/* a global lock of a different type exists */
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (tdb_have_extra_locks(tdb)) {
/* can't combine global and chain locks */
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (upgradable && ltype != F_RDLCK) {
/* tdb error: you can't upgrade a write lock! */
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
return 1;
}
/* We only need to lock individual bytes, but Linux merges consecutive locks
* so we lock in contiguous ranges. */
static int tdb_chainlock_gradual(struct tdb_context *tdb,
int ltype, enum tdb_lock_flags flags,
size_t off, size_t len)
{
int ret;
enum tdb_lock_flags nb_flags = (flags & ~TDB_LOCK_WAIT);
if (len <= 4) {
/* Single record. Just do blocking lock. */
return tdb_brlock(tdb, ltype, off, len, flags);
}
/* First we try non-blocking. */
ret = tdb_brlock(tdb, ltype, off, len, nb_flags);
if (ret == 0) {
return 0;
}
/* Try locking first half, then second. */
ret = tdb_chainlock_gradual(tdb, ltype, flags, off, len / 2);
if (ret == -1)
return -1;
ret = tdb_chainlock_gradual(tdb, ltype, flags,
off + len / 2, len - len / 2);
if (ret == -1) {
tdb_brunlock(tdb, ltype, off, len / 2);
return -1;
}
return 0;
}
/* lock/unlock entire database. It can only be upgradable if you have some
* other way of guaranteeing exclusivity (ie. transaction write lock).
* We do the locking gradually to avoid being starved by smaller locks. */
int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
enum tdb_lock_flags flags, bool upgradable)
{
int ret;
switch (tdb_allrecord_check(tdb, ltype, flags, upgradable)) {
case -1:
return -1;
case 0:
return 0;
}
/* We cover two kinds of locks:
* 1) Normal chain locks. Taken for almost all operations.
* 2) Individual records locks. Taken after normal or free
* chain locks.
*
* It is (1) which cause the starvation problem, so we're only
* gradual for that. */
if (tdb_have_mutexes(tdb)) {
ret = tdb_mutex_allrecord_lock(tdb, ltype, flags);
} else {
ret = tdb_chainlock_gradual(tdb, ltype, flags, FREELIST_TOP,
tdb->hash_size * 4);
}
if (ret == -1) {
return -1;
}
/* Grab individual record locks. */
if (tdb_brlock(tdb, ltype, lock_offset(tdb->hash_size), 0,
flags) == -1) {
if (tdb_have_mutexes(tdb)) {
tdb_mutex_allrecord_unlock(tdb);
} else {
tdb_brunlock(tdb, ltype, FREELIST_TOP,
tdb->hash_size * 4);
}
return -1;
}
tdb->allrecord_lock.count = 1;
/* If it's upgradable, it's actually exclusive so we can treat
* it as a write lock. */
tdb->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
tdb->allrecord_lock.off = upgradable;
if (tdb_needs_recovery(tdb)) {
bool mark = flags & TDB_LOCK_MARK_ONLY;
tdb_allrecord_unlock(tdb, ltype, mark);
if (mark) {
tdb->ecode = TDB_ERR_LOCK;
TDB_LOG((tdb, TDB_DEBUG_ERROR,
"tdb_lockall_mark cannot do recovery\n"));
return -1;
}
if (tdb_lock_and_recover(tdb) == -1) {
return -1;
}
return tdb_allrecord_lock(tdb, ltype, flags, upgradable);
}
return 0;
}
/* unlock entire db */
int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock)
{
/* There are no locks on read-only dbs */
if (tdb->read_only || tdb->traverse_read) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (tdb->allrecord_lock.count == 0) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
/* Upgradable locks are marked as write locks. */
if (tdb->allrecord_lock.ltype != (uint32_t)ltype
&& (!tdb->allrecord_lock.off || ltype != F_RDLCK)) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (tdb->allrecord_lock.count > 1) {
tdb->allrecord_lock.count--;
return 0;
}
if (!mark_lock) {
int ret;
if (tdb_have_mutexes(tdb)) {
ret = tdb_mutex_allrecord_unlock(tdb);
if (ret == 0) {
ret = tdb_brunlock(tdb, ltype,
lock_offset(tdb->hash_size),
0);
}
} else {
ret = tdb_brunlock(tdb, ltype, FREELIST_TOP, 0);
}
if (ret != 0) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed "
"(%s)\n", strerror(errno)));
return -1;
}
}
tdb->allrecord_lock.count = 0;
tdb->allrecord_lock.ltype = 0;
return 0;
}
/* lock entire database with write lock */
_PUBLIC_ int tdb_lockall(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall");
return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false);
}
/* lock entire database with write lock - mark only */
_PUBLIC_ int tdb_lockall_mark(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall_mark");
return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY, false);
}
/* unlock entire database with write lock - unmark only */
_PUBLIC_ int tdb_lockall_unmark(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall_unmark");
return tdb_allrecord_unlock(tdb, F_WRLCK, true);
}
/* lock entire database with write lock - nonblocking varient */
_PUBLIC_ int tdb_lockall_nonblock(struct tdb_context *tdb)
{
int ret = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_NOWAIT, false);
tdb_trace_ret(tdb, "tdb_lockall_nonblock", ret);
return ret;
}
/* unlock entire database with write lock */
_PUBLIC_ int tdb_unlockall(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_unlockall");
return tdb_allrecord_unlock(tdb, F_WRLCK, false);
}
/* lock entire database with read lock */
_PUBLIC_ int tdb_lockall_read(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall_read");
return tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false);
}
/* lock entire database with read lock - nonblock varient */
_PUBLIC_ int tdb_lockall_read_nonblock(struct tdb_context *tdb)
{
int ret = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_NOWAIT, false);
tdb_trace_ret(tdb, "tdb_lockall_read_nonblock", ret);
return ret;
}
/* unlock entire database with read lock */
_PUBLIC_ int tdb_unlockall_read(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_unlockall_read");
return tdb_allrecord_unlock(tdb, F_RDLCK, false);
}
/* lock/unlock one hash chain. This is meant to be used to reduce
contention - it cannot guarantee how many records will be locked */
_PUBLIC_ int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key)
{
int ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
tdb_trace_1rec(tdb, "tdb_chainlock", key);
return ret;
}
/* lock/unlock one hash chain, non-blocking. This is meant to be used
to reduce contention - it cannot guarantee how many records will be
locked */
_PUBLIC_ int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
{
int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
tdb_trace_1rec_ret(tdb, "tdb_chainlock_nonblock", key, ret);
return ret;
}
/* mark a chain as locked without actually locking it. Warning! use with great caution! */
_PUBLIC_ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
{
int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
F_WRLCK, TDB_LOCK_MARK_ONLY);
tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
return ret;
}
/* unmark a chain as locked without actually locking it. Warning! use with great caution! */
_PUBLIC_ int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
{
tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key);
return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
F_WRLCK, true);
}
_PUBLIC_ int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
{
tdb_trace_1rec(tdb, "tdb_chainunlock", key);
return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
}
_PUBLIC_ int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
{
int ret;
ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
tdb_trace_1rec(tdb, "tdb_chainlock_read", key);
return ret;
}
_PUBLIC_ int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
{
tdb_trace_1rec(tdb, "tdb_chainunlock_read", key);
return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
}
_PUBLIC_ int tdb_chainlock_read_nonblock(struct tdb_context *tdb, TDB_DATA key)
{
int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
tdb_trace_1rec_ret(tdb, "tdb_chainlock_read_nonblock", key, ret);
return ret;
}
/* record lock stops delete underneath */
int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
{
if (tdb->allrecord_lock.count) {
return 0;
}
return off ? tdb_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
}
/*
Write locks override our own fcntl readlocks, so check it here.
Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
an error to fail to get the lock here.
*/
int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
{
struct tdb_traverse_lock *i;
if (tdb == NULL) {
return -1;
}
for (i = &tdb->travlocks; i; i = i->next)
if (i->off == off)
return -1;
if (tdb->allrecord_lock.count) {
if (tdb->allrecord_lock.ltype == F_WRLCK) {
return 0;
}
return -1;
}
return tdb_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
}
int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
{
if (tdb->allrecord_lock.count) {
return 0;
}
return tdb_brunlock(tdb, F_WRLCK, off, 1);
}
/* fcntl locks don't stack: avoid unlocking someone else's */
int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
{
struct tdb_traverse_lock *i;
uint32_t count = 0;
if (tdb->allrecord_lock.count) {
return 0;
}
if (off == 0)
return 0;
for (i = &tdb->travlocks; i; i = i->next)
if (i->off == off)
count++;
return (count == 1 ? tdb_brunlock(tdb, F_RDLCK, off, 1) : 0);
}
bool tdb_have_extra_locks(struct tdb_context *tdb)
{
unsigned int extra = tdb->num_lockrecs;
/* A transaction holds the lock for all records. */
if (!tdb->transaction && tdb->allrecord_lock.count) {
return true;
}
/* We always hold the active lock if CLEAR_IF_FIRST. */
if (find_nestlock(tdb, ACTIVE_LOCK)) {
extra--;
}
/* In a transaction, we expect to hold the transaction lock */
if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) {
extra--;
}
return extra;
}
/* The transaction code uses this to remove all locks. */
void tdb_release_transaction_locks(struct tdb_context *tdb)
{
int i;
unsigned int active = 0;
if (tdb->allrecord_lock.count != 0) {
tdb_allrecord_unlock(tdb, tdb->allrecord_lock.ltype, false);
tdb->allrecord_lock.count = 0;
}
for (i=0;i<tdb->num_lockrecs;i++) {
struct tdb_lock_type *lck = &tdb->lockrecs[i];
/* Don't release the active lock! Copy it to first entry. */
if (lck->off == ACTIVE_LOCK) {
tdb->lockrecs[active++] = *lck;
} else {
tdb_brunlock(tdb, lck->ltype, lck->off, 1);
}
}
tdb->num_lockrecs = active;
}
/* Following functions are added specifically to support CTDB. */
/* Don't do actual fcntl locking, just mark tdb locked */
int tdb_transaction_write_lock_mark(struct tdb_context *tdb);
_PUBLIC_ int tdb_transaction_write_lock_mark(struct tdb_context *tdb)
{
return tdb_transaction_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY);
}
/* Don't do actual fcntl unlocking, just mark tdb unlocked */
int tdb_transaction_write_lock_unmark(struct tdb_context *tdb);
_PUBLIC_ int tdb_transaction_write_lock_unmark(struct tdb_context *tdb)
{
return tdb_nest_unlock(tdb, TRANSACTION_LOCK, F_WRLCK, true);
}