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/>.
22 #include "librpc/gen_ndr/messaging.h"
23 #include "ctdbd_conn.h"
24 #include "../lib/util/select.h"
25 #include "system/select.h"
27 static NTSTATUS
g_lock_force_unlock(struct g_lock_ctx
*ctx
, const char *name
,
28 struct server_id pid
);
31 struct db_context
*db
;
32 struct messaging_context
*msg
;
36 * The "g_lock.tdb" file contains records, indexed by the 0-terminated
37 * lockname. The record contains an array of "struct g_lock_rec"
38 * structures. Waiters have the lock_type with G_LOCK_PENDING or'ed.
42 enum g_lock_type lock_type
;
46 struct g_lock_ctx
*g_lock_ctx_init(TALLOC_CTX
*mem_ctx
,
47 struct messaging_context
*msg
)
49 struct g_lock_ctx
*result
;
51 result
= talloc(mem_ctx
, struct g_lock_ctx
);
57 result
->db
= db_open(result
, lock_path("g_lock.tdb"), 0,
58 TDB_CLEAR_IF_FIRST
|TDB_INCOMPATIBLE_HASH
, O_RDWR
|O_CREAT
, 0700);
59 if (result
->db
== NULL
) {
60 DEBUG(1, ("g_lock_init: Could not open g_lock.tdb"));
67 static bool g_lock_conflicts(enum g_lock_type lock_type
,
68 const struct g_lock_rec
*rec
)
70 enum g_lock_type rec_lock
= rec
->lock_type
;
72 if ((rec_lock
& G_LOCK_PENDING
) != 0) {
77 * Only tested write locks so far. Very likely this routine
78 * needs to be fixed for read locks....
80 if ((lock_type
== G_LOCK_READ
) && (rec_lock
== G_LOCK_READ
)) {
86 static bool g_lock_parse(TALLOC_CTX
*mem_ctx
, TDB_DATA data
,
87 int *pnum_locks
, struct g_lock_rec
**plocks
)
90 struct g_lock_rec
*locks
;
92 if ((data
.dsize
% sizeof(struct g_lock_rec
)) != 0) {
93 DEBUG(1, ("invalid lock record length %d\n", (int)data
.dsize
));
97 num_locks
= data
.dsize
/ sizeof(struct g_lock_rec
);
98 locks
= talloc_array(mem_ctx
, struct g_lock_rec
, num_locks
);
100 DEBUG(1, ("talloc failed\n"));
104 memcpy(locks
, data
.dptr
, data
.dsize
);
106 DEBUG(10, ("locks:\n"));
107 for (i
=0; i
<num_locks
; i
++) {
108 DEBUGADD(10, ("%s: %s %s\n",
109 procid_str(talloc_tos(), &locks
[i
].pid
),
110 ((locks
[i
].lock_type
& 1) == G_LOCK_READ
) ?
112 (locks
[i
].lock_type
& G_LOCK_PENDING
) ?
113 "(pending)" : "(owner)"));
115 if (((locks
[i
].lock_type
& G_LOCK_PENDING
) == 0)
116 && !process_exists(locks
[i
].pid
)) {
118 DEBUGADD(10, ("lock owner %s died -- discarding\n",
119 procid_str(talloc_tos(),
122 if (i
< (num_locks
-1)) {
123 locks
[i
] = locks
[num_locks
-1];
130 *pnum_locks
= num_locks
;
134 static void g_lock_cleanup(int *pnum_locks
, struct g_lock_rec
*locks
)
138 num_locks
= *pnum_locks
;
140 DEBUG(10, ("g_lock_cleanup: %d locks\n", num_locks
));
142 for (i
=0; i
<num_locks
; i
++) {
143 if (process_exists(locks
[i
].pid
)) {
146 DEBUGADD(10, ("%s does not exist -- discarding\n",
147 procid_str(talloc_tos(), &locks
[i
].pid
)));
149 if (i
< (num_locks
-1)) {
150 locks
[i
] = locks
[num_locks
-1];
154 *pnum_locks
= num_locks
;
158 static struct g_lock_rec
*g_lock_addrec(TALLOC_CTX
*mem_ctx
,
159 struct g_lock_rec
*locks
,
161 const struct server_id pid
,
162 enum g_lock_type lock_type
)
164 struct g_lock_rec
*result
;
165 int num_locks
= *pnum_locks
;
167 result
= talloc_realloc(mem_ctx
, locks
, struct g_lock_rec
,
169 if (result
== NULL
) {
173 result
[num_locks
].pid
= pid
;
174 result
[num_locks
].lock_type
= lock_type
;
179 static void g_lock_got_retry(struct messaging_context
*msg
,
182 struct server_id server_id
,
185 static NTSTATUS
g_lock_trylock(struct g_lock_ctx
*ctx
, const char *name
,
186 enum g_lock_type lock_type
)
188 struct db_record
*rec
= NULL
;
189 struct g_lock_rec
*locks
= NULL
;
191 struct server_id self
;
194 NTSTATUS status
= NT_STATUS_OK
;
195 NTSTATUS store_status
;
198 rec
= ctx
->db
->fetch_locked(ctx
->db
, talloc_tos(),
199 string_term_tdb_data(name
));
201 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name
));
202 status
= NT_STATUS_LOCK_NOT_GRANTED
;
206 if (!g_lock_parse(talloc_tos(), rec
->value
, &num_locks
, &locks
)) {
207 DEBUG(10, ("g_lock_parse for %s failed\n", name
));
208 status
= NT_STATUS_INTERNAL_ERROR
;
212 self
= messaging_server_id(ctx
->msg
);
215 for (i
=0; i
<num_locks
; i
++) {
216 if (procid_equal(&self
, &locks
[i
].pid
)) {
217 if (our_index
!= -1) {
218 DEBUG(1, ("g_lock_trylock: Added ourself "
220 status
= NT_STATUS_INTERNAL_ERROR
;
223 if ((locks
[i
].lock_type
& G_LOCK_PENDING
) == 0) {
224 DEBUG(1, ("g_lock_trylock: Found ourself not "
226 status
= NT_STATUS_INTERNAL_ERROR
;
232 /* never conflict with ourself */
235 if (g_lock_conflicts(lock_type
, &locks
[i
])) {
236 struct server_id pid
= locks
[i
].pid
;
238 if (!process_exists(pid
)) {
241 status
= g_lock_force_unlock(ctx
, name
, pid
);
242 if (!NT_STATUS_IS_OK(status
)) {
243 DEBUG(1, ("Could not unlock dead lock "
249 lock_type
|= G_LOCK_PENDING
;
253 if (our_index
== -1) {
254 /* First round, add ourself */
256 locks
= g_lock_addrec(talloc_tos(), locks
, &num_locks
,
259 DEBUG(10, ("g_lock_addrec failed\n"));
260 status
= NT_STATUS_NO_MEMORY
;
265 * Retry. We were pending last time. Overwrite the
266 * stored lock_type with what we calculated, we might
267 * have acquired the lock this time.
269 locks
[our_index
].lock_type
= lock_type
;
272 if (NT_STATUS_IS_OK(status
) && ((lock_type
& G_LOCK_PENDING
) == 0)) {
274 * Walk through the list of locks, search for dead entries
276 g_lock_cleanup(&num_locks
, locks
);
279 data
= make_tdb_data((uint8_t *)locks
, num_locks
* sizeof(*locks
));
280 store_status
= rec
->store(rec
, data
, 0);
281 if (!NT_STATUS_IS_OK(store_status
)) {
282 DEBUG(1, ("rec->store failed: %s\n",
283 nt_errstr(store_status
)));
284 status
= store_status
;
291 if (NT_STATUS_IS_OK(status
) && (lock_type
& G_LOCK_PENDING
) != 0) {
292 return STATUS_PENDING
;
298 NTSTATUS
g_lock_lock(struct g_lock_ctx
*ctx
, const char *name
,
299 enum g_lock_type lock_type
, struct timeval timeout
)
301 struct tevent_timer
*te
= NULL
;
304 struct timeval timeout_end
;
305 struct timeval time_now
;
307 DEBUG(10, ("Trying to acquire lock %d for %s\n", (int)lock_type
,
310 if (lock_type
& ~1) {
311 DEBUG(1, ("Got invalid lock type %d for %s\n",
312 (int)lock_type
, name
));
313 return NT_STATUS_INVALID_PARAMETER
;
316 #ifdef CLUSTER_SUPPORT
317 if (lp_clustering()) {
318 status
= ctdb_watch_us(messaging_ctdbd_connection());
319 if (!NT_STATUS_IS_OK(status
)) {
320 DEBUG(10, ("could not register retry with ctdb: %s\n",
327 status
= messaging_register(ctx
->msg
, &retry
, MSG_DBWRAP_G_LOCK_RETRY
,
329 if (!NT_STATUS_IS_OK(status
)) {
330 DEBUG(10, ("messaging_register failed: %s\n",
335 time_now
= timeval_current();
336 timeout_end
= timeval_sum(&time_now
, &timeout
);
339 struct pollfd
*pollfds
;
343 struct timeval timeout_remaining
, select_timeout
;
345 status
= g_lock_trylock(ctx
, name
, lock_type
);
346 if (NT_STATUS_IS_OK(status
)) {
347 DEBUG(10, ("Got lock %s\n", name
));
350 if (!NT_STATUS_EQUAL(status
, STATUS_PENDING
)) {
351 DEBUG(10, ("g_lock_trylock failed: %s\n",
356 DEBUG(10, ("g_lock_trylock: Did not get lock, waiting...\n"));
358 /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
359 * !!! HACK ALERT --- FIX ME !!!
360 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
361 * What we really want to do here is to react to
362 * MSG_DBWRAP_G_LOCK_RETRY messages that are either sent
363 * by a client doing g_lock_unlock or by ourselves when
364 * we receive a CTDB_SRVID_SAMBA_NOTIFY or
365 * CTDB_SRVID_RECONFIGURE message from ctdbd, i.e. when
366 * either a client holding a lock or a complete node
369 * Doing this properly involves calling tevent_loop_once(),
370 * but doing this here with the main ctdbd messaging context
371 * creates a nested event loop when g_lock_lock() is called
372 * from the main event loop, e.g. in a tcon_and_X where the
373 * share_info.tdb needs to be initialized and is locked by
374 * another process, or when the remore registry is accessed
375 * for writing and some other process already holds a lock
376 * on the registry.tdb.
378 * So as a quick fix, we act a little coarsely here: we do
379 * a select on the ctdb connection fd and when it is readable
380 * or we get EINTR, then we retry without actually parsing
381 * any ctdb packages or dispatching messages. This means that
382 * we retry more often than intended by design, but this does
383 * not harm and it is unobtrusive. When we have finished,
384 * the main loop will pick up all the messages and ctdb
385 * packets. The only extra twist is that we cannot use timed
386 * events here but have to handcode a timeout.
390 * We allocate 2 entries here. One is needed anyway for
391 * sys_poll and in the clustering case we might have to add
392 * the ctdb fd. This avoids the realloc then.
394 pollfds
= TALLOC_ARRAY(talloc_tos(), struct pollfd
, 2);
395 if (pollfds
== NULL
) {
396 status
= NT_STATUS_NO_MEMORY
;
401 #ifdef CLUSTER_SUPPORT
402 if (lp_clustering()) {
403 struct ctdbd_connection
*conn
;
404 conn
= messaging_ctdbd_connection();
406 pollfds
[0].fd
= ctdbd_conn_get_fd(conn
);
407 pollfds
[0].events
= POLLIN
|POLLHUP
;
413 time_now
= timeval_current();
414 timeout_remaining
= timeval_until(&time_now
, &timeout_end
);
415 select_timeout
= timeval_set(60, 0);
417 select_timeout
= timeval_min(&select_timeout
,
420 ret
= sys_poll(pollfds
, num_pollfds
,
421 timeval_to_msec(select_timeout
));
424 * We're not *really interested in the actual flags. We just
425 * need to retry this whole thing.
428 TALLOC_FREE(pollfds
);
432 if (errno
!= EINTR
) {
433 DEBUG(1, ("error calling select: %s\n",
435 status
= NT_STATUS_INTERNAL_ERROR
;
440 * This means a signal was received.
441 * It might have been a MSG_DBWRAP_G_LOCK_RETRY message.
444 } else if (ret
== 0) {
445 if (timeval_expired(&timeout_end
)) {
446 DEBUG(10, ("g_lock_lock timed out\n"));
447 status
= NT_STATUS_LOCK_NOT_GRANTED
;
450 DEBUG(10, ("select returned 0 but timeout not "
451 "not expired, retrying\n"));
453 } else if (ret
!= 1) {
454 DEBUG(1, ("invalid return code of select: %d\n", ret
));
455 status
= NT_STATUS_INTERNAL_ERROR
;
460 * This means ctdbd has sent us some data.
461 * Might be a CTDB_SRVID_RECONFIGURE or a
462 * CTDB_SRVID_SAMBA_NOTIFY message.
467 #ifdef CLUSTER_SUPPORT
471 if (!NT_STATUS_IS_OK(status
)) {
472 NTSTATUS unlock_status
;
474 unlock_status
= g_lock_unlock(ctx
, name
);
476 if (!NT_STATUS_IS_OK(unlock_status
)) {
477 DEBUG(1, ("Could not remove ourself from the locking "
478 "db: %s\n", nt_errstr(status
)));
482 messaging_deregister(ctx
->msg
, MSG_DBWRAP_G_LOCK_RETRY
, &retry
);
488 static void g_lock_got_retry(struct messaging_context
*msg
,
491 struct server_id server_id
,
494 bool *pretry
= (bool *)private_data
;
496 DEBUG(10, ("Got retry message from pid %s\n",
497 procid_str(talloc_tos(), &server_id
)));
502 static NTSTATUS
g_lock_force_unlock(struct g_lock_ctx
*ctx
, const char *name
,
503 struct server_id pid
)
505 struct db_record
*rec
= NULL
;
506 struct g_lock_rec
*locks
= NULL
;
508 enum g_lock_type lock_type
;
511 rec
= ctx
->db
->fetch_locked(ctx
->db
, talloc_tos(),
512 string_term_tdb_data(name
));
514 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name
));
515 status
= NT_STATUS_INTERNAL_ERROR
;
519 if (!g_lock_parse(talloc_tos(), rec
->value
, &num_locks
, &locks
)) {
520 DEBUG(10, ("g_lock_parse for %s failed\n", name
));
521 status
= NT_STATUS_INTERNAL_ERROR
;
525 for (i
=0; i
<num_locks
; i
++) {
526 if (procid_equal(&pid
, &locks
[i
].pid
)) {
531 if (i
== num_locks
) {
532 DEBUG(10, ("g_lock_force_unlock: Lock not found\n"));
533 status
= NT_STATUS_INTERNAL_ERROR
;
537 lock_type
= locks
[i
].lock_type
;
539 if (i
< (num_locks
-1)) {
540 locks
[i
] = locks
[num_locks
-1];
544 if (num_locks
== 0) {
545 status
= rec
->delete_rec(rec
);
548 data
= make_tdb_data((uint8_t *)locks
,
549 sizeof(struct g_lock_rec
) * num_locks
);
550 status
= rec
->store(rec
, data
, 0);
553 if (!NT_STATUS_IS_OK(status
)) {
554 DEBUG(1, ("g_lock_force_unlock: Could not store record: %s\n",
561 if ((lock_type
& G_LOCK_PENDING
) == 0) {
565 * We've been the lock holder. Others to retry. Don't
566 * tell all others to avoid a thundering herd. In case
567 * this leads to a complete stall because we miss some
568 * processes, the loop in g_lock_lock tries at least
572 for (i
=0; i
<num_locks
; i
++) {
573 if ((locks
[i
].lock_type
& G_LOCK_PENDING
) == 0) {
576 if (!process_exists(locks
[i
].pid
)) {
581 * Ping all waiters to retry
583 status
= messaging_send(ctx
->msg
, locks
[i
].pid
,
584 MSG_DBWRAP_G_LOCK_RETRY
,
586 if (!NT_STATUS_IS_OK(status
)) {
587 DEBUG(1, ("sending retry to %s failed: %s\n",
588 procid_str(talloc_tos(),
594 if (num_wakeups
> 5) {
601 * For the error path, TALLOC_FREE(rec) as well. In the good
602 * path we have already freed it.
610 NTSTATUS
g_lock_unlock(struct g_lock_ctx
*ctx
, const char *name
)
614 status
= g_lock_force_unlock(ctx
, name
, messaging_server_id(ctx
->msg
));
616 #ifdef CLUSTER_SUPPORT
617 if (lp_clustering()) {
618 ctdb_unwatch(messaging_ctdbd_connection());
624 struct g_lock_locks_state
{
625 int (*fn
)(const char *name
, void *private_data
);
629 static int g_lock_locks_fn(struct db_record
*rec
, void *priv
)
631 struct g_lock_locks_state
*state
= (struct g_lock_locks_state
*)priv
;
633 if ((rec
->key
.dsize
== 0) || (rec
->key
.dptr
[rec
->key
.dsize
-1] != 0)) {
634 DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
637 return state
->fn((char *)rec
->key
.dptr
, state
->private_data
);
640 int g_lock_locks(struct g_lock_ctx
*ctx
,
641 int (*fn
)(const char *name
, void *private_data
),
644 struct g_lock_locks_state state
;
647 state
.private_data
= private_data
;
649 return ctx
->db
->traverse_read(ctx
->db
, g_lock_locks_fn
, &state
);
652 NTSTATUS
g_lock_dump(struct g_lock_ctx
*ctx
, const char *name
,
653 int (*fn
)(struct server_id pid
,
654 enum g_lock_type lock_type
,
660 struct g_lock_rec
*locks
= NULL
;
663 if (ctx
->db
->fetch(ctx
->db
, talloc_tos(), string_term_tdb_data(name
),
665 return NT_STATUS_NOT_FOUND
;
668 if ((data
.dsize
== 0) || (data
.dptr
== NULL
)) {
672 ret
= g_lock_parse(talloc_tos(), data
, &num_locks
, &locks
);
674 TALLOC_FREE(data
.dptr
);
677 DEBUG(10, ("g_lock_parse for %s failed\n", name
));
678 return NT_STATUS_INTERNAL_ERROR
;
681 for (i
=0; i
<num_locks
; i
++) {
682 if (fn(locks
[i
].pid
, locks
[i
].lock_type
, private_data
) != 0) {
690 struct g_lock_get_state
{
692 struct server_id
*pid
;
695 static int g_lock_get_fn(struct server_id pid
, enum g_lock_type lock_type
,
698 struct g_lock_get_state
*state
= (struct g_lock_get_state
*)priv
;
700 if ((lock_type
& G_LOCK_PENDING
) != 0) {
709 NTSTATUS
g_lock_get(struct g_lock_ctx
*ctx
, const char *name
,
710 struct server_id
*pid
)
712 struct g_lock_get_state state
;
718 status
= g_lock_dump(ctx
, name
, g_lock_get_fn
, &state
);
719 if (!NT_STATUS_IS_OK(status
)) {
723 return NT_STATUS_NOT_FOUND
;
728 static bool g_lock_init_all(TALLOC_CTX
*mem_ctx
,
729 struct tevent_context
**pev
,
730 struct messaging_context
**pmsg
,
731 const struct server_id self
,
732 struct g_lock_ctx
**pg_ctx
)
734 struct tevent_context
*ev
= NULL
;
735 struct messaging_context
*msg
= NULL
;
736 struct g_lock_ctx
*g_ctx
= NULL
;
738 ev
= tevent_context_init(mem_ctx
);
740 d_fprintf(stderr
, "ERROR: could not init event context\n");
743 msg
= messaging_init(mem_ctx
, self
, ev
);
745 d_fprintf(stderr
, "ERROR: could not init messaging context\n");
748 g_ctx
= g_lock_ctx_init(mem_ctx
, msg
);
750 d_fprintf(stderr
, "ERROR: could not init g_lock context\n");
765 NTSTATUS
g_lock_do(const char *name
, enum g_lock_type lock_type
,
766 struct timeval timeout
, const struct server_id self
,
767 void (*fn
)(void *private_data
), void *private_data
)
769 struct tevent_context
*ev
= NULL
;
770 struct messaging_context
*msg
= NULL
;
771 struct g_lock_ctx
*g_ctx
= NULL
;
774 if (!g_lock_init_all(talloc_tos(), &ev
, &msg
, self
, &g_ctx
)) {
775 status
= NT_STATUS_ACCESS_DENIED
;
779 status
= g_lock_lock(g_ctx
, name
, lock_type
, timeout
);
780 if (!NT_STATUS_IS_OK(status
)) {
784 g_lock_unlock(g_ctx
, name
);