2 Unix SMB/CIFS implementation.
3 global locks based on dbwrap and messaging
4 Copyright (C) 2009 by Volker Lendecke
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #include "system/filesys.h"
23 #include "ctdbd_conn.h"
24 #include "../lib/util/select.h"
25 #include "system/select.h"
28 static NTSTATUS
g_lock_force_unlock(struct g_lock_ctx
*ctx
, const char *name
,
29 struct server_id pid
);
32 struct db_context
*db
;
33 struct messaging_context
*msg
;
37 * The "g_lock.tdb" file contains records, indexed by the 0-terminated
38 * lockname. The record contains an array of "struct g_lock_rec"
39 * structures. Waiters have the lock_type with G_LOCK_PENDING or'ed.
43 enum g_lock_type lock_type
;
47 struct g_lock_ctx
*g_lock_ctx_init(TALLOC_CTX
*mem_ctx
,
48 struct messaging_context
*msg
)
50 struct g_lock_ctx
*result
;
52 result
= talloc(mem_ctx
, struct g_lock_ctx
);
58 result
->db
= db_open(result
, lock_path("g_lock.tdb"), 0,
59 TDB_CLEAR_IF_FIRST
|TDB_INCOMPATIBLE_HASH
, O_RDWR
|O_CREAT
, 0700);
60 if (result
->db
== NULL
) {
61 DEBUG(1, ("g_lock_init: Could not open g_lock.tdb"));
68 static bool g_lock_conflicts(enum g_lock_type lock_type
,
69 const struct g_lock_rec
*rec
)
71 enum g_lock_type rec_lock
= rec
->lock_type
;
73 if ((rec_lock
& G_LOCK_PENDING
) != 0) {
78 * Only tested write locks so far. Very likely this routine
79 * needs to be fixed for read locks....
81 if ((lock_type
== G_LOCK_READ
) && (rec_lock
== G_LOCK_READ
)) {
87 static bool g_lock_parse(TALLOC_CTX
*mem_ctx
, TDB_DATA data
,
88 int *pnum_locks
, struct g_lock_rec
**plocks
)
91 struct g_lock_rec
*locks
;
93 if ((data
.dsize
% sizeof(struct g_lock_rec
)) != 0) {
94 DEBUG(1, ("invalid lock record length %d\n", (int)data
.dsize
));
98 num_locks
= data
.dsize
/ sizeof(struct g_lock_rec
);
99 locks
= talloc_array(mem_ctx
, struct g_lock_rec
, num_locks
);
101 DEBUG(1, ("talloc failed\n"));
105 memcpy(locks
, data
.dptr
, data
.dsize
);
107 DEBUG(10, ("locks:\n"));
108 for (i
=0; i
<num_locks
; i
++) {
109 DEBUGADD(10, ("%s: %s %s\n",
110 procid_str(talloc_tos(), &locks
[i
].pid
),
111 ((locks
[i
].lock_type
& 1) == G_LOCK_READ
) ?
113 (locks
[i
].lock_type
& G_LOCK_PENDING
) ?
114 "(pending)" : "(owner)"));
116 if (((locks
[i
].lock_type
& G_LOCK_PENDING
) == 0)
117 && !process_exists(locks
[i
].pid
)) {
119 DEBUGADD(10, ("lock owner %s died -- discarding\n",
120 procid_str(talloc_tos(),
123 if (i
< (num_locks
-1)) {
124 locks
[i
] = locks
[num_locks
-1];
131 *pnum_locks
= num_locks
;
135 static void g_lock_cleanup(int *pnum_locks
, struct g_lock_rec
*locks
)
139 num_locks
= *pnum_locks
;
141 DEBUG(10, ("g_lock_cleanup: %d locks\n", num_locks
));
143 for (i
=0; i
<num_locks
; i
++) {
144 if (process_exists(locks
[i
].pid
)) {
147 DEBUGADD(10, ("%s does not exist -- discarding\n",
148 procid_str(talloc_tos(), &locks
[i
].pid
)));
150 if (i
< (num_locks
-1)) {
151 locks
[i
] = locks
[num_locks
-1];
155 *pnum_locks
= num_locks
;
159 static struct g_lock_rec
*g_lock_addrec(TALLOC_CTX
*mem_ctx
,
160 struct g_lock_rec
*locks
,
162 const struct server_id pid
,
163 enum g_lock_type lock_type
)
165 struct g_lock_rec
*result
;
166 int num_locks
= *pnum_locks
;
168 result
= talloc_realloc(mem_ctx
, locks
, struct g_lock_rec
,
170 if (result
== NULL
) {
174 result
[num_locks
].pid
= pid
;
175 result
[num_locks
].lock_type
= lock_type
;
180 static void g_lock_got_retry(struct messaging_context
*msg
,
183 struct server_id server_id
,
186 static NTSTATUS
g_lock_trylock(struct g_lock_ctx
*ctx
, const char *name
,
187 enum g_lock_type lock_type
)
189 struct db_record
*rec
= NULL
;
190 struct g_lock_rec
*locks
= NULL
;
192 struct server_id self
;
195 NTSTATUS status
= NT_STATUS_OK
;
196 NTSTATUS store_status
;
199 rec
= ctx
->db
->fetch_locked(ctx
->db
, talloc_tos(),
200 string_term_tdb_data(name
));
202 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name
));
203 status
= NT_STATUS_LOCK_NOT_GRANTED
;
207 if (!g_lock_parse(talloc_tos(), rec
->value
, &num_locks
, &locks
)) {
208 DEBUG(10, ("g_lock_parse for %s failed\n", name
));
209 status
= NT_STATUS_INTERNAL_ERROR
;
213 self
= messaging_server_id(ctx
->msg
);
216 for (i
=0; i
<num_locks
; i
++) {
217 if (procid_equal(&self
, &locks
[i
].pid
)) {
218 if (our_index
!= -1) {
219 DEBUG(1, ("g_lock_trylock: Added ourself "
221 status
= NT_STATUS_INTERNAL_ERROR
;
224 if ((locks
[i
].lock_type
& G_LOCK_PENDING
) == 0) {
225 DEBUG(1, ("g_lock_trylock: Found ourself not "
227 status
= NT_STATUS_INTERNAL_ERROR
;
233 /* never conflict with ourself */
236 if (g_lock_conflicts(lock_type
, &locks
[i
])) {
237 struct server_id pid
= locks
[i
].pid
;
239 if (!process_exists(pid
)) {
242 status
= g_lock_force_unlock(ctx
, name
, pid
);
243 if (!NT_STATUS_IS_OK(status
)) {
244 DEBUG(1, ("Could not unlock dead lock "
250 lock_type
|= G_LOCK_PENDING
;
254 if (our_index
== -1) {
255 /* First round, add ourself */
257 locks
= g_lock_addrec(talloc_tos(), locks
, &num_locks
,
260 DEBUG(10, ("g_lock_addrec failed\n"));
261 status
= NT_STATUS_NO_MEMORY
;
266 * Retry. We were pending last time. Overwrite the
267 * stored lock_type with what we calculated, we might
268 * have acquired the lock this time.
270 locks
[our_index
].lock_type
= lock_type
;
273 if (NT_STATUS_IS_OK(status
) && ((lock_type
& G_LOCK_PENDING
) == 0)) {
275 * Walk through the list of locks, search for dead entries
277 g_lock_cleanup(&num_locks
, locks
);
280 data
= make_tdb_data((uint8_t *)locks
, num_locks
* sizeof(*locks
));
281 store_status
= rec
->store(rec
, data
, 0);
282 if (!NT_STATUS_IS_OK(store_status
)) {
283 DEBUG(1, ("rec->store failed: %s\n",
284 nt_errstr(store_status
)));
285 status
= store_status
;
292 if (NT_STATUS_IS_OK(status
) && (lock_type
& G_LOCK_PENDING
) != 0) {
293 return STATUS_PENDING
;
299 NTSTATUS
g_lock_lock(struct g_lock_ctx
*ctx
, const char *name
,
300 enum g_lock_type lock_type
, struct timeval timeout
)
302 struct tevent_timer
*te
= NULL
;
305 struct timeval timeout_end
;
306 struct timeval time_now
;
308 DEBUG(10, ("Trying to acquire lock %d for %s\n", (int)lock_type
,
311 if (lock_type
& ~1) {
312 DEBUG(1, ("Got invalid lock type %d for %s\n",
313 (int)lock_type
, name
));
314 return NT_STATUS_INVALID_PARAMETER
;
317 #ifdef CLUSTER_SUPPORT
318 if (lp_clustering()) {
319 status
= ctdb_watch_us(messaging_ctdbd_connection());
320 if (!NT_STATUS_IS_OK(status
)) {
321 DEBUG(10, ("could not register retry with ctdb: %s\n",
328 status
= messaging_register(ctx
->msg
, &retry
, MSG_DBWRAP_G_LOCK_RETRY
,
330 if (!NT_STATUS_IS_OK(status
)) {
331 DEBUG(10, ("messaging_register failed: %s\n",
336 time_now
= timeval_current();
337 timeout_end
= timeval_sum(&time_now
, &timeout
);
340 struct pollfd
*pollfds
;
344 struct timeval timeout_remaining
, select_timeout
;
346 status
= g_lock_trylock(ctx
, name
, lock_type
);
347 if (NT_STATUS_IS_OK(status
)) {
348 DEBUG(10, ("Got lock %s\n", name
));
351 if (!NT_STATUS_EQUAL(status
, STATUS_PENDING
)) {
352 DEBUG(10, ("g_lock_trylock failed: %s\n",
357 DEBUG(10, ("g_lock_trylock: Did not get lock, waiting...\n"));
359 /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
360 * !!! HACK ALERT --- FIX ME !!!
361 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
362 * What we really want to do here is to react to
363 * MSG_DBWRAP_G_LOCK_RETRY messages that are either sent
364 * by a client doing g_lock_unlock or by ourselves when
365 * we receive a CTDB_SRVID_SAMBA_NOTIFY or
366 * CTDB_SRVID_RECONFIGURE message from ctdbd, i.e. when
367 * either a client holding a lock or a complete node
370 * Doing this properly involves calling tevent_loop_once(),
371 * but doing this here with the main ctdbd messaging context
372 * creates a nested event loop when g_lock_lock() is called
373 * from the main event loop, e.g. in a tcon_and_X where the
374 * share_info.tdb needs to be initialized and is locked by
375 * another process, or when the remore registry is accessed
376 * for writing and some other process already holds a lock
377 * on the registry.tdb.
379 * So as a quick fix, we act a little coarsely here: we do
380 * a select on the ctdb connection fd and when it is readable
381 * or we get EINTR, then we retry without actually parsing
382 * any ctdb packages or dispatching messages. This means that
383 * we retry more often than intended by design, but this does
384 * not harm and it is unobtrusive. When we have finished,
385 * the main loop will pick up all the messages and ctdb
386 * packets. The only extra twist is that we cannot use timed
387 * events here but have to handcode a timeout.
391 * We allocate 2 entries here. One is needed anyway for
392 * sys_poll and in the clustering case we might have to add
393 * the ctdb fd. This avoids the realloc then.
395 pollfds
= TALLOC_ARRAY(talloc_tos(), struct pollfd
, 2);
396 if (pollfds
== NULL
) {
397 status
= NT_STATUS_NO_MEMORY
;
402 #ifdef CLUSTER_SUPPORT
403 if (lp_clustering()) {
404 struct ctdbd_connection
*conn
;
405 conn
= messaging_ctdbd_connection();
407 pollfds
[0].fd
= ctdbd_conn_get_fd(conn
);
408 pollfds
[0].events
= POLLIN
|POLLHUP
;
414 time_now
= timeval_current();
415 timeout_remaining
= timeval_until(&time_now
, &timeout_end
);
416 select_timeout
= timeval_set(60, 0);
418 select_timeout
= timeval_min(&select_timeout
,
421 ret
= sys_poll(pollfds
, num_pollfds
,
422 timeval_to_msec(select_timeout
));
425 * We're not *really interested in the actual flags. We just
426 * need to retry this whole thing.
429 TALLOC_FREE(pollfds
);
433 if (errno
!= EINTR
) {
434 DEBUG(1, ("error calling select: %s\n",
436 status
= NT_STATUS_INTERNAL_ERROR
;
441 * This means a signal was received.
442 * It might have been a MSG_DBWRAP_G_LOCK_RETRY message.
445 } else if (ret
== 0) {
446 if (timeval_expired(&timeout_end
)) {
447 DEBUG(10, ("g_lock_lock timed out\n"));
448 status
= NT_STATUS_LOCK_NOT_GRANTED
;
451 DEBUG(10, ("select returned 0 but timeout not "
452 "not expired, retrying\n"));
454 } else if (ret
!= 1) {
455 DEBUG(1, ("invalid return code of select: %d\n", ret
));
456 status
= NT_STATUS_INTERNAL_ERROR
;
461 * This means ctdbd has sent us some data.
462 * Might be a CTDB_SRVID_RECONFIGURE or a
463 * CTDB_SRVID_SAMBA_NOTIFY message.
468 #ifdef CLUSTER_SUPPORT
472 if (!NT_STATUS_IS_OK(status
)) {
473 NTSTATUS unlock_status
;
475 unlock_status
= g_lock_unlock(ctx
, name
);
477 if (!NT_STATUS_IS_OK(unlock_status
)) {
478 DEBUG(1, ("Could not remove ourself from the locking "
479 "db: %s\n", nt_errstr(status
)));
483 messaging_deregister(ctx
->msg
, MSG_DBWRAP_G_LOCK_RETRY
, &retry
);
489 static void g_lock_got_retry(struct messaging_context
*msg
,
492 struct server_id server_id
,
495 bool *pretry
= (bool *)private_data
;
497 DEBUG(10, ("Got retry message from pid %s\n",
498 procid_str(talloc_tos(), &server_id
)));
503 static NTSTATUS
g_lock_force_unlock(struct g_lock_ctx
*ctx
, const char *name
,
504 struct server_id pid
)
506 struct db_record
*rec
= NULL
;
507 struct g_lock_rec
*locks
= NULL
;
509 enum g_lock_type lock_type
;
512 rec
= ctx
->db
->fetch_locked(ctx
->db
, talloc_tos(),
513 string_term_tdb_data(name
));
515 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name
));
516 status
= NT_STATUS_INTERNAL_ERROR
;
520 if (!g_lock_parse(talloc_tos(), rec
->value
, &num_locks
, &locks
)) {
521 DEBUG(10, ("g_lock_parse for %s failed\n", name
));
522 status
= NT_STATUS_INTERNAL_ERROR
;
526 for (i
=0; i
<num_locks
; i
++) {
527 if (procid_equal(&pid
, &locks
[i
].pid
)) {
532 if (i
== num_locks
) {
533 DEBUG(10, ("g_lock_force_unlock: Lock not found\n"));
534 status
= NT_STATUS_INTERNAL_ERROR
;
538 lock_type
= locks
[i
].lock_type
;
540 if (i
< (num_locks
-1)) {
541 locks
[i
] = locks
[num_locks
-1];
545 if (num_locks
== 0) {
546 status
= rec
->delete_rec(rec
);
549 data
= make_tdb_data((uint8_t *)locks
,
550 sizeof(struct g_lock_rec
) * num_locks
);
551 status
= rec
->store(rec
, data
, 0);
554 if (!NT_STATUS_IS_OK(status
)) {
555 DEBUG(1, ("g_lock_force_unlock: Could not store record: %s\n",
562 if ((lock_type
& G_LOCK_PENDING
) == 0) {
566 * We've been the lock holder. Others to retry. Don't
567 * tell all others to avoid a thundering herd. In case
568 * this leads to a complete stall because we miss some
569 * processes, the loop in g_lock_lock tries at least
573 for (i
=0; i
<num_locks
; i
++) {
574 if ((locks
[i
].lock_type
& G_LOCK_PENDING
) == 0) {
577 if (!process_exists(locks
[i
].pid
)) {
582 * Ping all waiters to retry
584 status
= messaging_send(ctx
->msg
, locks
[i
].pid
,
585 MSG_DBWRAP_G_LOCK_RETRY
,
587 if (!NT_STATUS_IS_OK(status
)) {
588 DEBUG(1, ("sending retry to %s failed: %s\n",
589 procid_str(talloc_tos(),
595 if (num_wakeups
> 5) {
602 * For the error path, TALLOC_FREE(rec) as well. In the good
603 * path we have already freed it.
611 NTSTATUS
g_lock_unlock(struct g_lock_ctx
*ctx
, const char *name
)
615 status
= g_lock_force_unlock(ctx
, name
, messaging_server_id(ctx
->msg
));
617 #ifdef CLUSTER_SUPPORT
618 if (lp_clustering()) {
619 ctdb_unwatch(messaging_ctdbd_connection());
625 struct g_lock_locks_state
{
626 int (*fn
)(const char *name
, void *private_data
);
630 static int g_lock_locks_fn(struct db_record
*rec
, void *priv
)
632 struct g_lock_locks_state
*state
= (struct g_lock_locks_state
*)priv
;
634 if ((rec
->key
.dsize
== 0) || (rec
->key
.dptr
[rec
->key
.dsize
-1] != 0)) {
635 DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
638 return state
->fn((char *)rec
->key
.dptr
, state
->private_data
);
641 int g_lock_locks(struct g_lock_ctx
*ctx
,
642 int (*fn
)(const char *name
, void *private_data
),
645 struct g_lock_locks_state state
;
648 state
.private_data
= private_data
;
650 return ctx
->db
->traverse_read(ctx
->db
, g_lock_locks_fn
, &state
);
653 NTSTATUS
g_lock_dump(struct g_lock_ctx
*ctx
, const char *name
,
654 int (*fn
)(struct server_id pid
,
655 enum g_lock_type lock_type
,
661 struct g_lock_rec
*locks
= NULL
;
664 if (ctx
->db
->fetch(ctx
->db
, talloc_tos(), string_term_tdb_data(name
),
666 return NT_STATUS_NOT_FOUND
;
669 if ((data
.dsize
== 0) || (data
.dptr
== NULL
)) {
673 ret
= g_lock_parse(talloc_tos(), data
, &num_locks
, &locks
);
675 TALLOC_FREE(data
.dptr
);
678 DEBUG(10, ("g_lock_parse for %s failed\n", name
));
679 return NT_STATUS_INTERNAL_ERROR
;
682 for (i
=0; i
<num_locks
; i
++) {
683 if (fn(locks
[i
].pid
, locks
[i
].lock_type
, private_data
) != 0) {
691 struct g_lock_get_state
{
693 struct server_id
*pid
;
696 static int g_lock_get_fn(struct server_id pid
, enum g_lock_type lock_type
,
699 struct g_lock_get_state
*state
= (struct g_lock_get_state
*)priv
;
701 if ((lock_type
& G_LOCK_PENDING
) != 0) {
710 NTSTATUS
g_lock_get(struct g_lock_ctx
*ctx
, const char *name
,
711 struct server_id
*pid
)
713 struct g_lock_get_state state
;
719 status
= g_lock_dump(ctx
, name
, g_lock_get_fn
, &state
);
720 if (!NT_STATUS_IS_OK(status
)) {
724 return NT_STATUS_NOT_FOUND
;
729 static bool g_lock_init_all(TALLOC_CTX
*mem_ctx
,
730 struct tevent_context
**pev
,
731 struct messaging_context
**pmsg
,
732 const struct server_id self
,
733 struct g_lock_ctx
**pg_ctx
)
735 struct tevent_context
*ev
= NULL
;
736 struct messaging_context
*msg
= NULL
;
737 struct g_lock_ctx
*g_ctx
= NULL
;
739 ev
= tevent_context_init(mem_ctx
);
741 d_fprintf(stderr
, "ERROR: could not init event context\n");
744 msg
= messaging_init(mem_ctx
, self
, ev
);
746 d_fprintf(stderr
, "ERROR: could not init messaging context\n");
749 g_ctx
= g_lock_ctx_init(mem_ctx
, msg
);
751 d_fprintf(stderr
, "ERROR: could not init g_lock context\n");
766 NTSTATUS
g_lock_do(const char *name
, enum g_lock_type lock_type
,
767 struct timeval timeout
, const struct server_id self
,
768 void (*fn
)(void *private_data
), void *private_data
)
770 struct tevent_context
*ev
= NULL
;
771 struct messaging_context
*msg
= NULL
;
772 struct g_lock_ctx
*g_ctx
= NULL
;
775 if (!g_lock_init_all(talloc_tos(), &ev
, &msg
, self
, &g_ctx
)) {
776 status
= NT_STATUS_ACCESS_DENIED
;
780 status
= g_lock_lock(g_ctx
, name
, lock_type
, timeout
);
781 if (!NT_STATUS_IS_OK(status
)) {
785 g_lock_unlock(g_ctx
, name
);