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/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; }
static enum agent_return do_operation(enum operation op, const char *name) { TDB_DATA k; enum agent_return ret; TDB_DATA data; if (op != OPEN && op != OPEN_WITH_CLEAR_IF_FIRST && !tdb) { diag("external: No tdb open!"); return OTHER_FAILURE; } k.dptr = (void *)name; k.dsize = strlen(name); locking_would_block = 0; switch (op) { case OPEN: if (tdb) { diag("Already have tdb %s open", tdb_name(tdb)); return OTHER_FAILURE; } tdb = tdb_open_ex(name, 0, TDB_DEFAULT, O_RDWR, 0, &taplogctx, NULL); if (!tdb) { if (!locking_would_block) diag("Opening tdb gave %s", strerror(errno)); ret = OTHER_FAILURE; } else ret = SUCCESS; break; case OPEN_WITH_CLEAR_IF_FIRST: if (tdb) return OTHER_FAILURE; tdb = tdb_open_ex(name, 0, TDB_CLEAR_IF_FIRST, O_RDWR, 0, &taplogctx, NULL); ret = tdb ? SUCCESS : OTHER_FAILURE; break; case TRANSACTION_START: ret = tdb_transaction_start(tdb) == 0 ? SUCCESS : OTHER_FAILURE; break; case FETCH: data = tdb_fetch(tdb, k); if (data.dptr == NULL) { if (tdb_error(tdb) == TDB_ERR_NOEXIST) ret = FAILED; else ret = OTHER_FAILURE; } else if (data.dsize != k.dsize || memcmp(data.dptr, k.dptr, k.dsize) != 0) { ret = OTHER_FAILURE; } else { ret = SUCCESS; } free(data.dptr); break; case STORE: ret = tdb_store(tdb, k, k, 0) == 0 ? SUCCESS : OTHER_FAILURE; break; case TRANSACTION_COMMIT: ret = tdb_transaction_commit(tdb)==0 ? SUCCESS : OTHER_FAILURE; break; case CHECK: ret = tdb_check(tdb, NULL, NULL) == 0 ? SUCCESS : OTHER_FAILURE; break; case NEEDS_RECOVERY: ret = tdb_needs_recovery(tdb) ? SUCCESS : FAILED; break; case CLOSE: ret = tdb_close(tdb) == 0 ? SUCCESS : OTHER_FAILURE; tdb = NULL; break; default: ret = OTHER_FAILURE; } if (locking_would_block) ret = WOULD_HAVE_BLOCKED; return ret; }