LCOV - code coverage report
Current view: top level - lib/tdb/common - lock.c (source / functions) Hit Total Coverage
Test: coverage report for abartlet/fix-coverage dd10fb34 Lines: 315 384 82.0 %
Date: 2021-09-23 10:06:22 Functions: 44 48 91.7 %

          Line data    Source code
       1             :  /*
       2             :    Unix SMB/CIFS implementation.
       3             : 
       4             :    trivial database library
       5             : 
       6             :    Copyright (C) Andrew Tridgell              1999-2005
       7             :    Copyright (C) Paul `Rusty' Russell              2000
       8             :    Copyright (C) Jeremy Allison                    2000-2003
       9             : 
      10             :      ** NOTE! The following LGPL license applies to the tdb
      11             :      ** library. This does NOT imply that all of Samba is released
      12             :      ** under the LGPL
      13             : 
      14             :    This library is free software; you can redistribute it and/or
      15             :    modify it under the terms of the GNU Lesser General Public
      16             :    License as published by the Free Software Foundation; either
      17             :    version 3 of the License, or (at your option) any later version.
      18             : 
      19             :    This library is distributed in the hope that it will be useful,
      20             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
      21             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      22             :    Lesser General Public License for more details.
      23             : 
      24             :    You should have received a copy of the GNU Lesser General Public
      25             :    License along with this library; if not, see <http://www.gnu.org/licenses/>.
      26             : */
      27             : 
      28             : #include "tdb_private.h"
      29             : 
      30        5016 : _PUBLIC_ void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
      31             : {
      32        5016 :         tdb->interrupt_sig_ptr = ptr;
      33        5016 : }
      34             : 
      35   352575255 : static int fcntl_lock(struct tdb_context *tdb,
      36             :                       int rw, off_t off, off_t len, bool waitflag)
      37             : {
      38             :         struct flock fl;
      39             :         int cmd;
      40             : 
      41             : #ifdef USE_TDB_MUTEX_LOCKING
      42             :         {
      43             :                 int ret;
      44   352575255 :                 if (tdb_mutex_lock(tdb, rw, off, len, waitflag, &ret)) {
      45    82830021 :                         return ret;
      46             :                 }
      47             :         }
      48             : #endif
      49             : 
      50   269745234 :         fl.l_type = rw;
      51   269745234 :         fl.l_whence = SEEK_SET;
      52   269745234 :         fl.l_start = off;
      53   269745234 :         fl.l_len = len;
      54   269745234 :         fl.l_pid = 0;
      55             : 
      56   269745234 :         cmd = waitflag ? F_SETLKW : F_SETLK;
      57             : 
      58   269745234 :         return fcntl(tdb->fd, cmd, &fl);
      59             : }
      60             : 
      61   271747358 : static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
      62             : {
      63             :         struct flock fl;
      64             : #if 0 /* Check they matched up locks and unlocks correctly. */
      65             :         char line[80];
      66             :         FILE *locks;
      67             :         bool found = false;
      68             : 
      69             :         locks = fopen("/proc/locks", "r");
      70             : 
      71             :         while (fgets(line, 80, locks)) {
      72             :                 char *p;
      73             :                 int type, start, l;
      74             : 
      75             :                 /* eg. 1: FLOCK  ADVISORY  WRITE 2440 08:01:2180826 0 EOF */
      76             :                 p = strchr(line, ':') + 1;
      77             :                 if (strncmp(p, " POSIX  ADVISORY  ", strlen(" POSIX  ADVISORY  ")))
      78             :                         continue;
      79             :                 p += strlen(" FLOCK  ADVISORY  ");
      80             :                 if (strncmp(p, "READ  ", strlen("READ  ")) == 0)
      81             :                         type = F_RDLCK;
      82             :                 else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
      83             :                         type = F_WRLCK;
      84             :                 else
      85             :                         abort();
      86             :                 p += 6;
      87             :                 if (atoi(p) != getpid())
      88             :                         continue;
      89             :                 p = strchr(strchr(p, ' ') + 1, ' ') + 1;
      90             :                 start = atoi(p);
      91             :                 p = strchr(p, ' ') + 1;
      92             :                 if (strncmp(p, "EOF", 3) == 0)
      93             :                         l = 0;
      94             :                 else
      95             :                         l = atoi(p) - start + 1;
      96             : 
      97             :                 if (off == start) {
      98             :                         if (len != l) {
      99             :                                 fprintf(stderr, "Len %u should be %u: %s",
     100             :                                         (int)len, l, line);
     101             :                                 abort();
     102             :                         }
     103             :                         if (type != rw) {
     104             :                                 fprintf(stderr, "Type %s wrong: %s",
     105             :                                         rw == F_RDLCK ? "READ" : "WRITE", line);
     106             :                                 abort();
     107             :                         }
     108             :                         found = true;
     109             :                         break;
     110             :                 }
     111             :         }
     112             : 
     113             :         if (!found) {
     114             :                 fprintf(stderr, "Unlock on %u@%u not found!\n",
     115             :                         (int)off, (int)len);
     116             :                 abort();
     117             :         }
     118             : 
     119             :         fclose(locks);
     120             : #endif
     121             : 
     122             : #ifdef USE_TDB_MUTEX_LOCKING
     123             :         {
     124             :                 int ret;
     125   271747358 :                 if (tdb_mutex_unlock(tdb, rw, off, len, &ret)) {
     126    82830014 :                         return ret;
     127             :                 }
     128             :         }
     129             : #endif
     130             : 
     131   188917344 :         fl.l_type = F_UNLCK;
     132   188917344 :         fl.l_whence = SEEK_SET;
     133   188917344 :         fl.l_start = off;
     134   188917344 :         fl.l_len = len;
     135   188917344 :         fl.l_pid = 0;
     136             : 
     137   188917344 :         return fcntl(tdb->fd, F_SETLKW, &fl);
     138             : }
     139             : 
     140             : /*
     141             :  * Calculate the lock offset for a list
     142             :  *
     143             :  * list -1 is the freelist, otherwise a hash chain.
     144             :  *
     145             :  * Note that we consistently (but without real reason) lock hash chains at an
     146             :  * offset that is 4 bytes below the real offset of the corresponding list head
     147             :  * in the db.
     148             :  *
     149             :  * This is the memory layout of the hashchain array:
     150             :  *
     151             :  * FREELIST_TOP + 0 = freelist
     152             :  * FREELIST_TOP + 4 = hashtable list 0
     153             :  * FREELIST_TOP + 8 = hashtable list 1
     154             :  * ...
     155             :  *
     156             :  * Otoh lock_offset computes:
     157             :  *
     158             :  * freelist = FREELIST_TOP - 4
     159             :  * list 0   = FREELIST_TOP + 0
     160             :  * list 1   = FREELIST_TOP + 4
     161             :  * ...
     162             :  *
     163             :  * Unfortunately we can't change this calculation in order to align the locking
     164             :  * offset with the memory layout, as that would make the locking incompatible
     165             :  * between different tdb versions.
     166             :  */
     167  1748483846 : static tdb_off_t lock_offset(int list)
     168             : {
     169  1814964242 :         return FREELIST_TOP + 4*list;
     170             : }
     171             : 
     172             : /* a byte range locking function - return 0 on success
     173             :    this functions locks/unlocks "len" byte at the specified offset.
     174             : 
     175             :    On error, errno is also set so that errors are passed back properly
     176             :    through tdb_open().
     177             : 
     178             :    note that a len of zero means lock to end of file
     179             : */
     180   372540107 : int tdb_brlock(struct tdb_context *tdb,
     181             :                int rw_type, tdb_off_t offset, size_t len,
     182             :                enum tdb_lock_flags flags)
     183             : {
     184             :         int ret;
     185             : 
     186   372540107 :         if (tdb->flags & TDB_NOLOCK) {
     187    18281892 :                 return 0;
     188             :         }
     189             : 
     190   352575260 :         if (flags & TDB_LOCK_MARK_ONLY) {
     191           5 :                 return 0;
     192             :         }
     193             : 
     194   352575255 :         if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
     195           0 :                 tdb->ecode = TDB_ERR_RDONLY;
     196           0 :                 return -1;
     197             :         }
     198             : 
     199             :         do {
     200   352575255 :                 ret = fcntl_lock(tdb, rw_type, offset, len,
     201   352575255 :                                  flags & TDB_LOCK_WAIT);
     202             :                 /* Check for a sigalarm break. */
     203   352575255 :                 if (ret == -1 && errno == EINTR &&
     204           0 :                                 tdb->interrupt_sig_ptr &&
     205           0 :                                 *tdb->interrupt_sig_ptr) {
     206           0 :                         break;
     207             :                 }
     208   352575255 :         } while (ret == -1 && errno == EINTR);
     209             : 
     210   352575255 :         if (ret == -1) {
     211       25070 :                 tdb->ecode = TDB_ERR_LOCK;
     212             :                 /* Generic lock error. errno set by fcntl.
     213             :                  * EAGAIN is an expected return from non-blocking
     214             :                  * locks. */
     215       25070 :                 if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) {
     216           0 :                         TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %u rw_type=%d flags=%d len=%zu\n",
     217             :                                  tdb->fd, offset, rw_type, flags, len));
     218             :                 }
     219       24919 :                 return -1;
     220             :         }
     221   344820943 :         return 0;
     222             : }
     223             : 
     224   291712203 : int tdb_brunlock(struct tdb_context *tdb,
     225             :                  int rw_type, tdb_off_t offset, size_t len)
     226             : {
     227             :         int ret;
     228             : 
     229   291712203 :         if (tdb->flags & TDB_NOLOCK) {
     230    18281890 :                 return 0;
     231             :         }
     232             : 
     233             :         do {
     234   271747358 :                 ret = fcntl_unlock(tdb, rw_type, offset, len);
     235   271747349 :         } while (ret == -1 && errno == EINTR);
     236             : 
     237   271747349 :         if (ret == -1) {
     238         147 :                 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %u rw_type=%u len=%zu\n",
     239             :                          tdb->fd, offset, rw_type, len));
     240             :         }
     241   266092657 :         return ret;
     242             : }
     243             : 
     244             : /*
     245             :  * Do a tdb_brlock in a loop. Some OSes (such as solaris) have too
     246             :  * conservative deadlock detection and claim a deadlock when progress can be
     247             :  * made. For those OSes we may loop for a while.
     248             :  */
     249             : 
     250     1221309 : static int tdb_brlock_retry(struct tdb_context *tdb,
     251             :                             int rw_type, tdb_off_t offset, size_t len,
     252             :                             enum tdb_lock_flags flags)
     253             : {
     254     1221309 :         int count = 1000;
     255             : 
     256     2277674 :         while (count--) {
     257             :                 struct timeval tv;
     258             :                 int ret;
     259             : 
     260     1221309 :                 ret = tdb_brlock(tdb, rw_type, offset, len, flags);
     261     1221309 :                 if (ret == 0) {
     262     1221307 :                         return 0;
     263             :                 }
     264           2 :                 if (errno != EDEADLK) {
     265           2 :                         break;
     266             :                 }
     267             :                 /* sleep for as short a time as we can - more portable than usleep() */
     268           0 :                 tv.tv_sec = 0;
     269           0 :                 tv.tv_usec = 1;
     270           0 :                 select(0, NULL, NULL, NULL, &tv);
     271             :         }
     272           2 :         return -1;
     273             : }
     274             : 
     275             : /*
     276             :   upgrade a read lock to a write lock.
     277             : */
     278     1221309 : int tdb_allrecord_upgrade(struct tdb_context *tdb)
     279             : {
     280             :         int ret;
     281             : 
     282     1221309 :         if (tdb->allrecord_lock.count != 1) {
     283           0 :                 TDB_LOG((tdb, TDB_DEBUG_ERROR,
     284             :                          "tdb_allrecord_upgrade failed: count %u too high\n",
     285             :                          tdb->allrecord_lock.count));
     286           0 :                 tdb->ecode = TDB_ERR_LOCK;
     287           0 :                 return -1;
     288             :         }
     289             : 
     290     1221309 :         if (tdb->allrecord_lock.off != 1) {
     291           0 :                 TDB_LOG((tdb, TDB_DEBUG_ERROR,
     292             :                          "tdb_allrecord_upgrade failed: already upgraded?\n"));
     293           0 :                 tdb->ecode = TDB_ERR_LOCK;
     294           0 :                 return -1;
     295             :         }
     296             : 
     297     1221309 :         if (tdb_have_mutexes(tdb)) {
     298           2 :                 ret = tdb_mutex_allrecord_upgrade(tdb);
     299           2 :                 if (ret == -1) {
     300           0 :                         goto fail;
     301             :                 }
     302           2 :                 ret = tdb_brlock_retry(tdb, F_WRLCK, lock_offset(tdb->hash_size),
     303             :                                        0, TDB_LOCK_WAIT|TDB_LOCK_PROBE);
     304           2 :                 if (ret == -1) {
     305           0 :                         tdb_mutex_allrecord_downgrade(tdb);
     306             :                 }
     307             :         } else {
     308     1221307 :                 ret = tdb_brlock_retry(tdb, F_WRLCK, FREELIST_TOP, 0,
     309             :                                        TDB_LOCK_WAIT|TDB_LOCK_PROBE);
     310             :         }
     311             : 
     312     1221309 :         if (ret == 0) {
     313     1221307 :                 tdb->allrecord_lock.ltype = F_WRLCK;
     314     1221307 :                 tdb->allrecord_lock.off = 0;
     315     1221307 :                 return 0;
     316             :         }
     317           2 : fail:
     318           2 :         TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_allrecord_upgrade failed\n"));
     319           2 :         return -1;
     320             : }
     321             : 
     322   552415280 : static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
     323             :                                            tdb_off_t offset)
     324             : {
     325             :         int i;
     326             : 
     327   794828795 :         for (i=0; i<tdb->num_lockrecs; i++) {
     328   532264294 :                 if (tdb->lockrecs[i].off == offset) {
     329   285348889 :                         return &tdb->lockrecs[i];
     330             :                 }
     331             :         }
     332   267066391 :         return NULL;
     333             : }
     334             : 
     335             : /* lock an offset in the database. */
     336   457243846 : int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
     337             :                   enum tdb_lock_flags flags)
     338             : {
     339             :         struct tdb_lock_type *new_lck;
     340             : 
     341   477511348 :         if (offset >= lock_offset(tdb->hash_size)) {
     342           0 :                 tdb->ecode = TDB_ERR_LOCK;
     343           0 :                 TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
     344             :                          offset, ltype));
     345           0 :                 return -1;
     346             :         }
     347   457243846 :         if (tdb->flags & TDB_NOLOCK)
     348   201773447 :                 return 0;
     349             : 
     350   243297325 :         new_lck = find_nestlock(tdb, offset);
     351   239250111 :         if (new_lck) {
     352    50531997 :                 if ((new_lck->ltype == F_RDLCK) && (ltype == F_WRLCK)) {
     353        4724 :                         if (!tdb_have_mutexes(tdb)) {
     354             :                                 int ret;
     355             :                                 /*
     356             :                                  * Upgrade the underlying fcntl
     357             :                                  * lock. Mutexes don't do readlocks,
     358             :                                  * so this only applies to fcntl
     359             :                                  * locking.
     360             :                                  */
     361           1 :                                 ret = tdb_brlock(tdb, ltype, offset, 1, flags);
     362           1 :                                 if (ret != 0) {
     363           1 :                                         return ret;
     364             :                                 }
     365             :                         }
     366        4723 :                         new_lck->ltype = F_WRLCK;
     367             :                 }
     368             :                 /*
     369             :                  * Just increment the in-memory struct, posix locks
     370             :                  * don't stack.
     371             :                  */
     372    50531996 :                 new_lck->count++;
     373    50531996 :                 return 0;
     374             :         }
     375             : 
     376   188718114 :         if (tdb->num_lockrecs == tdb->lockrecs_array_length) {
     377     4245985 :                 new_lck = (struct tdb_lock_type *)realloc(
     378     2323761 :                         tdb->lockrecs,
     379     2323761 :                         sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1));
     380     2323761 :                 if (new_lck == NULL) {
     381           0 :                         errno = ENOMEM;
     382           0 :                         return -1;
     383             :                 }
     384     2323761 :                 tdb->lockrecs_array_length = tdb->num_lockrecs+1;
     385     2323761 :                 tdb->lockrecs = new_lck;
     386             :         }
     387             : 
     388             :         /* Since fcntl locks don't nest, we do a lock for the first one,
     389             :            and simply bump the count for future ones */
     390   188718114 :         if (tdb_brlock(tdb, ltype, offset, 1, flags)) {
     391       21782 :                 return -1;
     392             :         }
     393             : 
     394   188696181 :         new_lck = &tdb->lockrecs[tdb->num_lockrecs];
     395             : 
     396   188696181 :         new_lck->off = offset;
     397   188696181 :         new_lck->count = 1;
     398   188696181 :         new_lck->ltype = ltype;
     399   188696181 :         tdb->num_lockrecs++;
     400             : 
     401   188696181 :         return 0;
     402             : }
     403             : 
     404          64 : static int tdb_lock_and_recover(struct tdb_context *tdb)
     405             : {
     406             :         int ret;
     407             : 
     408             :         /* We need to match locking order in transaction commit. */
     409          64 :         if (tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT)) {
     410           0 :                 return -1;
     411             :         }
     412             : 
     413          64 :         if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT)) {
     414           0 :                 tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
     415           0 :                 return -1;
     416             :         }
     417             : 
     418          64 :         ret = tdb_transaction_recover(tdb);
     419             : 
     420          64 :         tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1);
     421          64 :         tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
     422             : 
     423          64 :         return ret;
     424             : }
     425             : 
     426   422532760 : static bool have_data_locks(const struct tdb_context *tdb)
     427             : {
     428             :         int i;
     429             : 
     430   503006074 :         for (i = 0; i < tdb->num_lockrecs; i++) {
     431   160913662 :                 if (tdb->lockrecs[i].off >= lock_offset(-1))
     432    79636780 :                         return true;
     433             :         }
     434   342895980 :         return false;
     435             : }
     436             : 
     437             : /*
     438             :  * A allrecord lock allows us to avoid per chain locks. Check if the allrecord
     439             :  * lock is strong enough.
     440             :  */
     441  1939721878 : static int tdb_lock_covered_by_allrecord_lock(struct tdb_context *tdb,
     442             :                                               int ltype)
     443             : {
     444  1965070976 :         if (ltype == F_RDLCK) {
     445             :                 /*
     446             :                  * The allrecord_lock is equal (F_RDLCK) or stronger
     447             :                  * (F_WRLCK). Pass.
     448             :                  */
     449  1519818684 :                 return 0;
     450             :         }
     451             : 
     452   431938322 :         if (tdb->allrecord_lock.ltype == F_RDLCK) {
     453             :                 /*
     454             :                  * We ask for ltype==F_WRLCK, but the allrecord_lock
     455             :                  * is too weak. We can't upgrade here, so fail.
     456             :                  */
     457           0 :                 tdb->ecode = TDB_ERR_LOCK;
     458           0 :                 return -1;
     459             :         }
     460             : 
     461             :         /*
     462             :          * Asking for F_WRLCK, allrecord is F_WRLCK as well. Pass.
     463             :          */
     464   419903194 :         return 0;
     465             : }
     466             : 
     467  1425138634 : static int tdb_lock_list(struct tdb_context *tdb, int list, int ltype,
     468             :                          enum tdb_lock_flags waitflag)
     469             : {
     470             :         int ret;
     471  1425138634 :         bool check = false;
     472             : 
     473  1425138634 :         if (tdb->allrecord_lock.count) {
     474   982535488 :                 return tdb_lock_covered_by_allrecord_lock(tdb, ltype);
     475             :         }
     476             : 
     477             :         /*
     478             :          * Check for recoveries: Someone might have kill -9'ed a process
     479             :          * during a commit.
     480             :          */
     481   462673532 :         check = !have_data_locks(tdb);
     482   442603146 :         ret = tdb_nest_lock(tdb, lock_offset(list), ltype, waitflag);
     483             : 
     484   442603146 :         if (ret == 0 && check && tdb_needs_recovery(tdb)) {
     485          16 :                 tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
     486             : 
     487          16 :                 if (tdb_lock_and_recover(tdb) == -1) {
     488           0 :                         return -1;
     489             :                 }
     490          16 :                 return tdb_lock_list(tdb, list, ltype, waitflag);
     491             :         }
     492   422532744 :         return ret;
     493             : }
     494             : 
     495             : /* lock a list in the database. list -1 is the alloc list */
     496  1424091961 : int tdb_lock(struct tdb_context *tdb, int list, int ltype)
     497             : {
     498             :         int ret;
     499             : 
     500  1424091961 :         ret = tdb_lock_list(tdb, list, ltype, TDB_LOCK_WAIT);
     501  1424091961 :         if (ret) {
     502           0 :                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
     503             :                          "ltype=%d (%s)\n",  list, ltype, strerror(errno)));
     504             :         }
     505  1424091961 :         return ret;
     506             : }
     507             : 
     508             : /* lock a list in the database. list -1 is the alloc list. non-blocking lock */
     509             : _PUBLIC_ int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype);
     510     1046657 : _PUBLIC_ int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
     511             : {
     512     1046657 :         return tdb_lock_list(tdb, list, ltype, TDB_LOCK_NOWAIT);
     513             : }
     514             : 
     515             : 
     516   457085303 : int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
     517             :                     bool mark_lock)
     518             : {
     519   457085303 :         int ret = -1;
     520             :         struct tdb_lock_type *lck;
     521             : 
     522   457085303 :         if (tdb->flags & TDB_NOLOCK)
     523   206153315 :                 return 0;
     524             : 
     525             :         /* Sanity checks */
     526   238594345 :         if (offset >= lock_offset(tdb->hash_size)) {
     527           0 :                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->hash_size));
     528           0 :                 return ret;
     529             :         }
     530             : 
     531   238594345 :         lck = find_nestlock(tdb, offset);
     532   234579045 :         if ((lck == NULL) || (lck->count == 0)) {
     533           0 :                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
     534           0 :                 return -1;
     535             :         }
     536             : 
     537   234579045 :         if (lck->count > 1) {
     538    50531996 :                 lck->count--;
     539    50531996 :                 return 0;
     540             :         }
     541             : 
     542             :         /*
     543             :          * This lock has count==1 left, so we need to unlock it in the
     544             :          * kernel. We don't bother with decrementing the in-memory array
     545             :          * element, we're about to overwrite it with the last array element
     546             :          * anyway.
     547             :          */
     548             : 
     549   184047049 :         if (mark_lock) {
     550           2 :                 ret = 0;
     551             :         } else {
     552   184047047 :                 ret = tdb_brunlock(tdb, ltype, offset, 1);
     553             :         }
     554             : 
     555             :         /*
     556             :          * Shrink the array by overwriting the element just unlocked with the
     557             :          * last array element.
     558             :          */
     559   184047049 :         *lck = tdb->lockrecs[--tdb->num_lockrecs];
     560             : 
     561             :         /*
     562             :          * We don't bother with realloc when the array shrinks, but if we have
     563             :          * a completely idle tdb we should get rid of the locked array.
     564             :          */
     565             : 
     566   184047049 :         if (ret)
     567           0 :                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n"));
     568   180486328 :         return ret;
     569             : }
     570             : 
     571             : _PUBLIC_ int tdb_unlock(struct tdb_context *tdb, int list, int ltype);
     572  1425138605 : _PUBLIC_ int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
     573             : {
     574             :         /* a global lock allows us to avoid per chain locks */
     575  1425138605 :         if (tdb->allrecord_lock.count) {
     576   982535488 :                 return tdb_lock_covered_by_allrecord_lock(tdb, ltype);
     577             :         }
     578             : 
     579   442603117 :         return tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
     580             : }
     581             : 
     582             : /*
     583             :   get the transaction lock
     584             :  */
     585     7401428 : int tdb_transaction_lock(struct tdb_context *tdb, int ltype,
     586             :                          enum tdb_lock_flags lockflags)
     587             : {
     588     7401428 :         return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, lockflags);
     589             : }
     590             : 
     591             : /*
     592             :   release the transaction lock
     593             :  */
     594     4398723 : int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
     595             : {
     596     4398723 :         return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false);
     597             : }
     598             : 
     599             : /* Returns 0 if all done, -1 if error, 1 if ok. */
     600    79278744 : static int tdb_allrecord_check(struct tdb_context *tdb, int ltype,
     601             :                                enum tdb_lock_flags flags, bool upgradable)
     602             : {
     603             :         /* There are no locks on read-only dbs */
     604    79278744 :         if (tdb->read_only || tdb->traverse_read) {
     605           0 :                 tdb->ecode = TDB_ERR_LOCK;
     606           0 :                 return -1;
     607             :         }
     608             : 
     609    79278860 :         if (tdb->allrecord_lock.count &&
     610         119 :             tdb->allrecord_lock.ltype == (uint32_t)ltype) {
     611         119 :                 tdb->allrecord_lock.count++;
     612         119 :                 return 0;
     613             :         }
     614             : 
     615    79278625 :         if (tdb->allrecord_lock.count) {
     616             :                 /* a global lock of a different type exists */
     617           0 :                 tdb->ecode = TDB_ERR_LOCK;
     618           0 :                 return -1;
     619             :         }
     620             : 
     621    79278625 :         if (tdb_have_extra_locks(tdb)) {
     622             :                 /* can't combine global and chain locks */
     623      125525 :                 tdb->ecode = TDB_ERR_LOCK;
     624      125525 :                 return -1;
     625             :         }
     626             : 
     627    79153100 :         if (upgradable && ltype != F_RDLCK) {
     628             :                 /* tdb error: you can't upgrade a write lock! */
     629           0 :                 tdb->ecode = TDB_ERR_LOCK;
     630           0 :                 return -1;
     631             :         }
     632    77096277 :         return 1;
     633             : }
     634             : 
     635             : /* We only need to lock individual bytes, but Linux merges consecutive locks
     636             :  * so we lock in contiguous ranges. */
     637    79158827 : static int tdb_chainlock_gradual(struct tdb_context *tdb,
     638             :                                  int ltype, enum tdb_lock_flags flags,
     639             :                                  size_t off, size_t len)
     640             : {
     641             :         int ret;
     642    79158827 :         enum tdb_lock_flags nb_flags = (flags & ~TDB_LOCK_WAIT);
     643             : 
     644    79158827 :         if (len <= 4) {
     645             :                 /* Single record.  Just do blocking lock. */
     646        6723 :                 return tdb_brlock(tdb, ltype, off, len, flags);
     647             :         }
     648             : 
     649             :         /* First we try non-blocking. */
     650    79152104 :         ret = tdb_brlock(tdb, ltype, off, len, nb_flags);
     651    79152104 :         if (ret == 0) {
     652    77092410 :                 return 0;
     653             :         }
     654             : 
     655             :         /* Try locking first half, then second. */
     656        2871 :         ret = tdb_chainlock_gradual(tdb, ltype, flags, off, len / 2);
     657        2871 :         if (ret == -1)
     658           2 :                 return -1;
     659             : 
     660        5310 :         ret = tdb_chainlock_gradual(tdb, ltype, flags,
     661        5310 :                                     off + len / 2, len - len / 2);
     662        2869 :         if (ret == -1) {
     663           0 :                 tdb_brunlock(tdb, ltype, off, len / 2);
     664           0 :                 return -1;
     665             :         }
     666        2869 :         return 0;
     667             : }
     668             : 
     669             : /* lock/unlock entire database.  It can only be upgradable if you have some
     670             :  * other way of guaranteeing exclusivity (ie. transaction write lock).
     671             :  * We do the locking gradually to avoid being starved by smaller locks. */
     672    79278744 : int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
     673             :                        enum tdb_lock_flags flags, bool upgradable)
     674             : {
     675             :         int ret;
     676             : 
     677    79278744 :         switch (tdb_allrecord_check(tdb, ltype, flags, upgradable)) {
     678      122875 :         case -1:
     679      122875 :                 return -1;
     680         119 :         case 0:
     681         119 :                 return 0;
     682             :         }
     683             : 
     684             :         /* We cover two kinds of locks:
     685             :          * 1) Normal chain locks.  Taken for almost all operations.
     686             :          * 2) Individual records locks.  Taken after normal or free
     687             :          *    chain locks.
     688             :          *
     689             :          * It is (1) which cause the starvation problem, so we're only
     690             :          * gradual for that. */
     691             : 
     692    79153100 :         if (tdb_have_mutexes(tdb)) {
     693          13 :                 ret = tdb_mutex_allrecord_lock(tdb, ltype, flags);
     694             :         } else {
     695    79153087 :                 ret = tdb_chainlock_gradual(tdb, ltype, flags, FREELIST_TOP,
     696    79153087 :                                             tdb->hash_size * 4);
     697             :         }
     698             : 
     699    79153100 :         if (ret == -1) {
     700           3 :                 return -1;
     701             :         }
     702             : 
     703             :         /* Grab individual record locks. */
     704    81209920 :         if (tdb_brlock(tdb, ltype, lock_offset(tdb->hash_size), 0,
     705             :                        flags) == -1) {
     706           0 :                 if (tdb_have_mutexes(tdb)) {
     707           0 :                         tdb_mutex_allrecord_unlock(tdb);
     708             :                 } else {
     709           0 :                         tdb_brunlock(tdb, ltype, FREELIST_TOP,
     710           0 :                                      tdb->hash_size * 4);
     711             :                 }
     712           0 :                 return -1;
     713             :         }
     714             : 
     715    79153097 :         tdb->allrecord_lock.count = 1;
     716             :         /* If it's upgradable, it's actually exclusive so we can treat
     717             :          * it as a write lock. */
     718    79153097 :         tdb->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
     719    79153097 :         tdb->allrecord_lock.off = upgradable;
     720             : 
     721    79153097 :         if (tdb_needs_recovery(tdb)) {
     722          48 :                 bool mark = flags & TDB_LOCK_MARK_ONLY;
     723          48 :                 tdb_allrecord_unlock(tdb, ltype, mark);
     724          48 :                 if (mark) {
     725           0 :                         tdb->ecode = TDB_ERR_LOCK;
     726           0 :                         TDB_LOG((tdb, TDB_DEBUG_ERROR,
     727             :                                  "tdb_lockall_mark cannot do recovery\n"));
     728           0 :                         return -1;
     729             :                 }
     730          48 :                 if (tdb_lock_and_recover(tdb) == -1) {
     731          40 :                         return -1;
     732             :                 }
     733           8 :                 return tdb_allrecord_lock(tdb, ltype, flags, upgradable);
     734             :         }
     735             : 
     736    77096226 :         return 0;
     737             : }
     738             : 
     739             : 
     740             : 
     741             : /* unlock entire db */
     742    79152773 : int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock)
     743             : {
     744             :         /* There are no locks on read-only dbs */
     745    79152773 :         if (tdb->read_only || tdb->traverse_read) {
     746           0 :                 tdb->ecode = TDB_ERR_LOCK;
     747           0 :                 return -1;
     748             :         }
     749             : 
     750    79152773 :         if (tdb->allrecord_lock.count == 0) {
     751           0 :                 tdb->ecode = TDB_ERR_LOCK;
     752           0 :                 return -1;
     753             :         }
     754             : 
     755             :         /* Upgradable locks are marked as write locks. */
     756    79152773 :         if (tdb->allrecord_lock.ltype != (uint32_t)ltype
     757           8 :             && (!tdb->allrecord_lock.off || ltype != F_RDLCK)) {
     758           0 :                 tdb->ecode = TDB_ERR_LOCK;
     759           0 :                 return -1;
     760             :         }
     761             : 
     762    79152773 :         if (tdb->allrecord_lock.count > 1) {
     763         119 :                 tdb->allrecord_lock.count--;
     764         119 :                 return 0;
     765             :         }
     766             : 
     767    79152654 :         if (!mark_lock) {
     768             :                 int ret;
     769             : 
     770    79152652 :                 if (tdb_have_mutexes(tdb)) {
     771           7 :                         ret = tdb_mutex_allrecord_unlock(tdb);
     772           7 :                         if (ret == 0) {
     773           7 :                                 ret = tdb_brunlock(tdb, ltype,
     774           7 :                                                    lock_offset(tdb->hash_size),
     775             :                                                    0);
     776             :                         }
     777             :                 } else {
     778    79152645 :                         ret = tdb_brunlock(tdb, ltype, FREELIST_TOP, 0);
     779             :                 }
     780             : 
     781    79152649 :                 if (ret != 0) {
     782          45 :                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed "
     783             :                                  "(%s)\n", strerror(errno)));
     784          45 :                         return -1;
     785             :                 }
     786             :         }
     787             : 
     788    79152606 :         tdb->allrecord_lock.count = 0;
     789    79152606 :         tdb->allrecord_lock.ltype = 0;
     790             : 
     791    79152606 :         return 0;
     792             : }
     793             : 
     794             : /* lock entire database with write lock */
     795      126163 : _PUBLIC_ int tdb_lockall(struct tdb_context *tdb)
     796             : {
     797             :         tdb_trace(tdb, "tdb_lockall");
     798      126163 :         return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false);
     799             : }
     800             : 
     801             : /* lock entire database with write lock - mark only */
     802           2 : _PUBLIC_ int tdb_lockall_mark(struct tdb_context *tdb)
     803             : {
     804             :         tdb_trace(tdb, "tdb_lockall_mark");
     805           2 :         return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY, false);
     806             : }
     807             : 
     808             : /* unlock entire database with write lock - unmark only */
     809           2 : _PUBLIC_ int tdb_lockall_unmark(struct tdb_context *tdb)
     810             : {
     811             :         tdb_trace(tdb, "tdb_lockall_unmark");
     812           2 :         return tdb_allrecord_unlock(tdb, F_WRLCK, true);
     813             : }
     814             : 
     815             : /* lock entire database with write lock - nonblocking varient */
     816           2 : _PUBLIC_ int tdb_lockall_nonblock(struct tdb_context *tdb)
     817             : {
     818           2 :         int ret = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_NOWAIT, false);
     819             :         tdb_trace_ret(tdb, "tdb_lockall_nonblock", ret);
     820           2 :         return ret;
     821             : }
     822             : 
     823             : /* unlock entire database with write lock */
     824         620 : _PUBLIC_ int tdb_unlockall(struct tdb_context *tdb)
     825             : {
     826             :         tdb_trace(tdb, "tdb_unlockall");
     827         620 :         return tdb_allrecord_unlock(tdb, F_WRLCK, false);
     828             : }
     829             : 
     830             : /* lock entire database with read lock */
     831    76149865 : _PUBLIC_ int tdb_lockall_read(struct tdb_context *tdb)
     832             : {
     833             :         tdb_trace(tdb, "tdb_lockall_read");
     834    76149865 :         return tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false);
     835             : }
     836             : 
     837             : /* lock entire database with read lock - nonblock varient */
     838           0 : _PUBLIC_ int tdb_lockall_read_nonblock(struct tdb_context *tdb)
     839             : {
     840           0 :         int ret = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_NOWAIT, false);
     841             :         tdb_trace_ret(tdb, "tdb_lockall_read_nonblock", ret);
     842           0 :         return ret;
     843             : }
     844             : 
     845             : /* unlock entire database with read lock */
     846    76149404 : _PUBLIC_ int tdb_unlockall_read(struct tdb_context *tdb)
     847             : {
     848             :         tdb_trace(tdb, "tdb_unlockall_read");
     849    76149404 :         return tdb_allrecord_unlock(tdb, F_RDLCK, false);
     850             : }
     851             : 
     852             : /* lock/unlock one hash chain. This is meant to be used to reduce
     853             :    contention - it cannot guarantee how many records will be locked */
     854    11712033 : _PUBLIC_ int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key)
     855             : {
     856    11712033 :         int ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
     857             :         tdb_trace_1rec(tdb, "tdb_chainlock", key);
     858    11712033 :         return ret;
     859             : }
     860             : 
     861             : /* lock/unlock one hash chain, non-blocking. This is meant to be used
     862             :    to reduce contention - it cannot guarantee how many records will be
     863             :    locked */
     864           9 : _PUBLIC_ int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
     865             : {
     866           9 :         int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
     867             :         tdb_trace_1rec_ret(tdb, "tdb_chainlock_nonblock", key, ret);
     868           9 :         return ret;
     869             : }
     870             : 
     871             : /* mark a chain as locked without actually locking it. Warning! use with great caution! */
     872           2 : _PUBLIC_ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
     873             : {
     874           2 :         int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
     875             :                                 F_WRLCK, TDB_LOCK_MARK_ONLY);
     876             :         tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
     877           2 :         return ret;
     878             : }
     879             : 
     880             : /* unmark a chain as locked without actually locking it. Warning! use with great caution! */
     881           2 : _PUBLIC_ int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
     882             : {
     883             :         tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key);
     884           2 :         return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
     885             :                                F_WRLCK, true);
     886             : }
     887             : 
     888    11712031 : _PUBLIC_ int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
     889             : {
     890             :         tdb_trace_1rec(tdb, "tdb_chainunlock", key);
     891    11712031 :         return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
     892             : }
     893             : 
     894         262 : _PUBLIC_ int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
     895             : {
     896             :         int ret;
     897         262 :         ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
     898             :         tdb_trace_1rec(tdb, "tdb_chainlock_read", key);
     899         262 :         return ret;
     900             : }
     901             : 
     902         260 : _PUBLIC_ int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
     903             : {
     904             :         tdb_trace_1rec(tdb, "tdb_chainunlock_read", key);
     905         260 :         return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
     906             : }
     907             : 
     908           0 : _PUBLIC_ int tdb_chainlock_read_nonblock(struct tdb_context *tdb, TDB_DATA key)
     909             : {
     910           0 :         int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
     911             :         tdb_trace_1rec_ret(tdb, "tdb_chainlock_read_nonblock", key, ret);
     912           0 :         return ret;
     913             : }
     914             : 
     915             : /* record lock stops delete underneath */
     916   460608625 : int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
     917             : {
     918   460608625 :         if (tdb->allrecord_lock.count) {
     919   435349756 :                 return 0;
     920             :         }
     921    22012408 :         return off ? tdb_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
     922             : }
     923             : 
     924             : /*
     925             :   Write locks override our own fcntl readlocks, so check it here.
     926             :   Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
     927             :   an error to fail to get the lock here.
     928             : */
     929     3825474 : int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
     930             : {
     931             :         struct tdb_traverse_lock *i;
     932     3825474 :         if (tdb == NULL) {
     933           0 :                 return -1;
     934             :         }
     935     7722838 :         for (i = &tdb->travlocks; i; i = i->next)
     936     3980514 :                 if (i->off == off)
     937       51782 :                         return -1;
     938     3742324 :         if (tdb->allrecord_lock.count) {
     939     1802105 :                 if (tdb->allrecord_lock.ltype == F_WRLCK) {
     940     1643798 :                         return 0;
     941             :                 }
     942           0 :                 return -1;
     943             :         }
     944     1940219 :         return tdb_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
     945             : }
     946             : 
     947     3742062 : int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
     948             : {
     949     3742062 :         if (tdb->allrecord_lock.count) {
     950     1643798 :                 return 0;
     951             :         }
     952     1939957 :         return tdb_brunlock(tdb, F_WRLCK, off, 1);
     953             : }
     954             : 
     955             : /* fcntl locks don't stack: avoid unlocking someone else's */
     956   460608655 : int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
     957             : {
     958             :         struct tdb_traverse_lock *i;
     959   460608655 :         uint32_t count = 0;
     960             : 
     961   460608655 :         if (tdb->allrecord_lock.count) {
     962   435349752 :                 return 0;
     963             :         }
     964             : 
     965    22012442 :         if (off == 0)
     966          12 :                 return 0;
     967    66037028 :         for (i = &tdb->travlocks; i; i = i->next)
     968    44024620 :                 if (i->off == off)
     969    22012410 :                         count++;
     970    22012408 :         return (count == 1 ? tdb_brunlock(tdb, F_RDLCK, off, 1) : 0);
     971             : }
     972             : 
     973    84545087 : bool tdb_have_extra_locks(struct tdb_context *tdb)
     974             : {
     975    84545087 :         unsigned int extra = tdb->num_lockrecs;
     976             : 
     977             :         /* A transaction holds the lock for all records. */
     978    84545087 :         if (!tdb->transaction && tdb->allrecord_lock.count) {
     979           0 :                 return true;
     980             :         }
     981             : 
     982             :         /* We always hold the active lock if CLEAR_IF_FIRST. */
     983    84545087 :         if (find_nestlock(tdb, ACTIVE_LOCK)) {
     984      515722 :                 extra--;
     985             :         }
     986             : 
     987             :         /* In a transaction, we expect to hold the transaction lock */
     988    84569025 :         if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) {
     989     4224015 :                 extra--;
     990             :         }
     991             : 
     992    84545087 :         return extra;
     993             : }
     994             : 
     995             : /* The transaction code uses this to remove all locks. */
     996     3002702 : void tdb_release_transaction_locks(struct tdb_context *tdb)
     997             : {
     998             :         int i;
     999     3002702 :         unsigned int active = 0;
    1000             : 
    1001     3002702 :         if (tdb->allrecord_lock.count != 0) {
    1002     3002696 :                 tdb_allrecord_unlock(tdb, tdb->allrecord_lock.ltype, false);
    1003     3002693 :                 tdb->allrecord_lock.count = 0;
    1004             :         }
    1005             : 
    1006     7217682 :         for (i=0;i<tdb->num_lockrecs;i++) {
    1007     4229028 :                 struct tdb_lock_type *lck = &tdb->lockrecs[i];
    1008             : 
    1009             :                 /* Don't release the active lock!  Copy it to first entry. */
    1010     4229028 :                 if (lck->off == ACTIVE_LOCK) {
    1011        5019 :                         tdb->lockrecs[active++] = *lck;
    1012             :                 } else {
    1013     4224009 :                         tdb_brunlock(tdb, lck->ltype, lck->off, 1);
    1014             :                 }
    1015             :         }
    1016     3002693 :         tdb->num_lockrecs = active;
    1017     3002693 : }
    1018             : 
    1019             : /* Following functions are added specifically to support CTDB. */
    1020             : 
    1021             : /* Don't do actual fcntl locking, just mark tdb locked */
    1022             : _PUBLIC_ int tdb_transaction_write_lock_mark(struct tdb_context *tdb);
    1023           0 : _PUBLIC_ int tdb_transaction_write_lock_mark(struct tdb_context *tdb)
    1024             : {
    1025           0 :         return tdb_transaction_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY);
    1026             : }
    1027             : 
    1028             : /* Don't do actual fcntl unlocking, just mark tdb unlocked */
    1029             : _PUBLIC_ int tdb_transaction_write_lock_unmark(struct tdb_context *tdb);
    1030           0 : _PUBLIC_ int tdb_transaction_write_lock_unmark(struct tdb_context *tdb)
    1031             : {
    1032           0 :         return tdb_nest_unlock(tdb, TRANSACTION_LOCK, F_WRLCK, true);
    1033             : }

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