X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb2%2Ftdb1_lock.c;h=2252e4791b91c9d8d2afb392b9fd3c87f86d9056;hp=85348df04dc67c0a4e2504127bf4b7ccd1e2a2b1;hb=fbad02b680b6cbc33ae305ae1cbcdead4eedc7b1;hpb=60210a73ec08a7b34ba637ad19e6749cf6dc1952 diff --git a/ccan/tdb2/tdb1_lock.c b/ccan/tdb2/tdb1_lock.c index 85348df0..2252e479 100644 --- a/ccan/tdb2/tdb1_lock.c +++ b/ccan/tdb2/tdb1_lock.c @@ -27,93 +27,6 @@ #include "tdb1_private.h" -static int fcntl_lock(struct tdb1_context *tdb, - int rw, off_t off, off_t len, bool waitflag) -{ - struct flock fl; - - fl.l_type = rw; - fl.l_whence = SEEK_SET; - fl.l_start = off; - fl.l_len = len; - fl.l_pid = 0; - - if (waitflag) - return fcntl(tdb->file->fd, F_SETLKW, &fl); - else - return fcntl(tdb->file->fd, F_SETLK, &fl); -} - -static int fcntl_unlock(struct tdb1_context *tdb, int rw, off_t off, off_t len) -{ - struct flock fl; -#if 0 /* Check they matched up locks and unlocks correctly. */ - char line[80]; - FILE *locks; - bool found = false; - - locks = fopen("/proc/locks", "r"); - - while (fgets(line, 80, locks)) { - char *p; - int type, start, l; - - /* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */ - p = strchr(line, ':') + 1; - if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY "))) - continue; - p += strlen(" FLOCK ADVISORY "); - if (strncmp(p, "READ ", strlen("READ ")) == 0) - type = F_RDLCK; - else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0) - type = F_WRLCK; - else - abort(); - p += 6; - if (atoi(p) != getpid()) - continue; - p = strchr(strchr(p, ' ') + 1, ' ') + 1; - start = atoi(p); - p = strchr(p, ' ') + 1; - if (strncmp(p, "EOF", 3) == 0) - l = 0; - else - l = atoi(p) - start + 1; - - if (off == start) { - if (len != l) { - fprintf(stderr, "Len %u should be %u: %s", - (int)len, l, line); - abort(); - } - if (type != rw) { - fprintf(stderr, "Type %s wrong: %s", - rw == F_RDLCK ? "READ" : "WRITE", line); - abort(); - } - found = true; - break; - } - } - - if (!found) { - fprintf(stderr, "Unlock on %u@%u not found!\n", - (int)off, (int)len); - abort(); - } - - fclose(locks); -#endif - - fl.l_type = F_UNLCK; - fl.l_whence = SEEK_SET; - fl.l_start = off; - fl.l_len = len; - fl.l_pid = 0; - - return fcntl(tdb->file->fd, F_SETLKW, &fl); -} - /* list -1 is the alloc list, otherwise a hash chain. */ static tdb1_off_t lock_offset(int list) { @@ -132,102 +45,30 @@ int tdb1_brlock(struct tdb1_context *tdb, int rw_type, tdb1_off_t offset, size_t len, enum tdb_lock_flags flags) { - int ret; - - if (tdb->flags & TDB_NOLOCK) { + enum TDB_ERROR ecode = tdb_brlock(tdb, rw_type, offset, len, flags + | TDB_LOCK_NOCHECK); + if (ecode == TDB_SUCCESS) return 0; - } - - if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) { - tdb->last_error = TDB_ERR_RDONLY; - return -1; - } - - do { - ret = fcntl_lock(tdb, rw_type, offset, len, - flags & TDB_LOCK_WAIT); - } while (ret == -1 && errno == EINTR); - - if (ret == -1) { - tdb->last_error = TDB_ERR_LOCK; - /* Generic lock error. errno set by fcntl. - * EAGAIN is an expected return from non-blocking - * locks. */ - if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) { - tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, - "tdb1_brlock failed (fd=%d) at offset %d rw_type=%d flags=%d len=%d", - tdb->file->fd, offset, rw_type, flags, (int)len); - } - return -1; - } - return 0; + tdb->last_error = ecode; + return -1; } int tdb1_brunlock(struct tdb1_context *tdb, int rw_type, tdb1_off_t offset, size_t len) { - int ret; - - if (tdb->flags & TDB_NOLOCK) { + enum TDB_ERROR ecode = tdb_brunlock(tdb, rw_type, offset, len); + if (ecode == TDB_SUCCESS) return 0; - } - - do { - ret = fcntl_unlock(tdb, rw_type, offset, len); - } while (ret == -1 && errno == EINTR); - - if (ret == -1) { - tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, - "tdb1_brunlock failed (fd=%d) at offset" - " %d rw_type=%d len=%d", - tdb->file->fd, offset, rw_type, (int)len); - } - return ret; + tdb->last_error = ecode; + return -1; } -/* - upgrade a read lock to a write lock. This needs to be handled in a - special way as some OSes (such as solaris) have too conservative - deadlock detection and claim a deadlock when progress can be - made. For those OSes we may loop for a while. -*/ int tdb1_allrecord_upgrade(struct tdb1_context *tdb) { - int count = 1000; - - if (tdb->file->allrecord_lock.count != 1) { - tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, - "tdb1_allrecord_upgrade failed: " - "count %u too high", - tdb->file->allrecord_lock.count); - return -1; - } - - if (tdb->file->allrecord_lock.off != 1) { - tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, - "tdb1_allrecord_upgrade failed:" - " already upgraded?"); - return -1; - } - - while (count--) { - struct timeval tv; - if (tdb1_brlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0, - TDB_LOCK_WAIT|TDB_LOCK_PROBE) == 0) { - tdb->file->allrecord_lock.ltype = F_WRLCK; - tdb->file->allrecord_lock.off = 0; - return 0; - } - if (errno != EDEADLK) { - break; - } - /* sleep for as short a time as we can - more portable than usleep() */ - tv.tv_sec = 0; - tv.tv_usec = 1; - select(0, NULL, NULL, NULL, &tv); - } - tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, - "tdb1_allrecord_upgrade failed"); + enum TDB_ERROR ecode = tdb_allrecord_upgrade(tdb, TDB1_FREELIST_TOP); + if (ecode == TDB_SUCCESS) + return 0; + tdb->last_error = ecode; return -1; } @@ -248,7 +89,7 @@ static struct tdb_lock *tdb1_find_nestlock(struct tdb1_context *tdb, int tdb1_nest_lock(struct tdb1_context *tdb, uint32_t offset, int ltype, enum tdb_lock_flags flags) { - struct tdb_lock *new_lck; + enum TDB_ERROR ecode; if (offset >= lock_offset(tdb->header.hash_size)) { tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, @@ -257,39 +98,12 @@ int tdb1_nest_lock(struct tdb1_context *tdb, uint32_t offset, int ltype, offset, ltype); return -1; } - if (tdb->flags & TDB_NOLOCK) - return 0; - new_lck = tdb1_find_nestlock(tdb, offset); - if (new_lck) { - /* - * Just increment the in-memory struct, posix locks - * don't stack. - */ - new_lck->count++; - return 0; - } - - new_lck = (struct tdb_lock *)realloc( - tdb->file->lockrecs, - sizeof(*tdb->file->lockrecs) * (tdb->file->num_lockrecs+1)); - if (new_lck == NULL) { - errno = ENOMEM; + ecode = tdb_nest_lock(tdb, offset, ltype, flags | TDB_LOCK_NOCHECK); + if (unlikely(ecode != TDB_SUCCESS)) { + tdb->last_error = ecode; return -1; } - tdb->file->lockrecs = new_lck; - - /* Since fcntl locks don't nest, we do a lock for the first one, - and simply bump the count for future ones */ - if (tdb1_brlock(tdb, ltype, offset, 1, flags)) { - return -1; - } - - tdb->file->lockrecs[tdb->file->num_lockrecs].off = offset; - tdb->file->lockrecs[tdb->file->num_lockrecs].count = 1; - tdb->file->lockrecs[tdb->file->num_lockrecs].ltype = ltype; - tdb->file->num_lockrecs++; - return 0; } @@ -298,11 +112,13 @@ static int tdb1_lock_and_recover(struct tdb1_context *tdb) int ret; /* We need to match locking order in transaction commit. */ - if (tdb1_brlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0, TDB_LOCK_WAIT)) { + if (tdb1_brlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0, + TDB_LOCK_WAIT|TDB_LOCK_NOCHECK)) { return -1; } - if (tdb1_brlock(tdb, F_WRLCK, TDB1_OPEN_LOCK, 1, TDB_LOCK_WAIT)) { + if (tdb1_brlock(tdb, F_WRLCK, TDB1_OPEN_LOCK, 1, + TDB_LOCK_WAIT|TDB_LOCK_NOCHECK)) { tdb1_brunlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0); return -1; } @@ -374,57 +190,22 @@ int tdb1_lock(struct tdb1_context *tdb, int list, int ltype) int tdb1_nest_unlock(struct tdb1_context *tdb, uint32_t offset, int ltype) { - int ret = -1; - struct tdb_lock *lck; - - if (tdb->flags & TDB_NOLOCK) - return 0; + enum TDB_ERROR ecode; /* Sanity checks */ if (offset >= lock_offset(tdb->header.hash_size)) { tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, "tdb1_unlock: offset %u invalid (%d)", offset, tdb->header.hash_size); - return ret; - } - - lck = tdb1_find_nestlock(tdb, offset); - if ((lck == NULL) || (lck->count == 0)) { - tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR, - "tdb1_unlock: count is 0"); return -1; } - if (lck->count > 1) { - lck->count--; - return 0; - } - - /* - * This lock has count==1 left, so we need to unlock it in the - * kernel. We don't bother with decrementing the in-memory array - * element, we're about to overwrite it with the last array element - * anyway. - */ - - ret = tdb1_brunlock(tdb, ltype, offset, 1); - - /* - * Shrink the array by overwriting the element just unlocked with the - * last array element. - */ - *lck = tdb->file->lockrecs[--tdb->file->num_lockrecs]; - - /* - * We don't bother with realloc when the array shrinks, but if we have - * a completely idle tdb we should get rid of the locked array. - */ - - if (tdb->file->num_lockrecs == 0) { - SAFE_FREE(tdb->file->lockrecs); + ecode = tdb_nest_unlock(tdb, offset, ltype); + if (unlikely(ecode != TDB_SUCCESS)) { + tdb->last_error = ecode; + return -1; } - - return ret; + return 0; } int tdb1_unlock(struct tdb1_context *tdb, int list, int ltype) @@ -460,87 +241,46 @@ int tdb1_transaction_unlock(struct tdb1_context *tdb, int ltype) return tdb1_nest_unlock(tdb, TDB1_TRANSACTION_LOCK, ltype); } -/* Returns 0 if all done, -1 if error, 1 if ok. */ -static int tdb1_allrecord_check(struct tdb1_context *tdb, int ltype, - enum tdb_lock_flags flags, bool upgradable) +/* 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 tdb1_allrecord_lock(struct tdb1_context *tdb, int ltype, + enum tdb_lock_flags flags, bool upgradable) { - /* There are no locks on read-only dbs */ - if (tdb->read_only || tdb->traverse_read) { - tdb->last_error = TDB_ERR_LOCK; + enum TDB_ERROR ecode; + + /* tdb_lock_gradual() doesn't know about tdb->traverse_read. */ + if (tdb->traverse_read && !(tdb->flags & TDB_NOLOCK)) { + tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, + TDB_LOG_USE_ERROR, + "tdb1_allrecord_lock during" + " tdb1_read_traverse"); return -1; } - if (tdb->file->allrecord_lock.count && tdb->file->allrecord_lock.ltype == ltype) { + if (tdb->file->allrecord_lock.count + && tdb->file->allrecord_lock.ltype == ltype) { tdb->file->allrecord_lock.count++; return 0; } - if (tdb->file->allrecord_lock.count) { - /* a global lock of a different type exists */ - tdb->last_error = TDB_ERR_LOCK; - return -1; - } - if (tdb1_have_extra_locks(tdb)) { /* can't combine global and chain locks */ - tdb->last_error = TDB_ERR_LOCK; + tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, + TDB_LOG_USE_ERROR, + "tdb1_allrecord_lock holding" + " other locks"); return -1; } if (upgradable && ltype != F_RDLCK) { /* tdb error: you can't upgrade a write lock! */ - tdb->last_error = TDB_ERR_LOCK; - return -1; - } - return 1; -} - -/* We only need to lock individual bytes, but Linux merges consecutive locks - * so we lock in contiguous ranges. */ -static int tdb1_chainlock_gradual(struct tdb1_context *tdb, - int ltype, enum tdb_lock_flags flags, - size_t off, size_t len) -{ - int ret; - enum tdb_lock_flags nb_flags = (flags & ~TDB_LOCK_WAIT); - - if (len <= 4) { - /* Single record. Just do blocking lock. */ - return tdb1_brlock(tdb, ltype, off, len, flags); - } - - /* First we try non-blocking. */ - ret = tdb1_brlock(tdb, ltype, off, len, nb_flags); - if (ret == 0) { - return 0; - } - - /* Try locking first half, then second. */ - ret = tdb1_chainlock_gradual(tdb, ltype, flags, off, len / 2); - if (ret == -1) - return -1; - - ret = tdb1_chainlock_gradual(tdb, ltype, flags, - off + len / 2, len - len / 2); - if (ret == -1) { - tdb1_brunlock(tdb, ltype, off, len / 2); + tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, + TDB_LOG_ERROR, + "tdb1_allrecord_lock cannot" + " have upgradable write lock"); return -1; } - return 0; -} - -/* lock/unlock entire database. It can only be upgradable if you have some - * other way of guaranteeing exclusivity (ie. transaction write lock). - * We do the locking gradually to avoid being starved by smaller locks. */ -int tdb1_allrecord_lock(struct tdb1_context *tdb, int ltype, - enum tdb_lock_flags flags, bool upgradable) -{ - switch (tdb1_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. @@ -549,8 +289,10 @@ int tdb1_allrecord_lock(struct tdb1_context *tdb, int ltype, * * It is (1) which cause the starvation problem, so we're only * gradual for that. */ - if (tdb1_chainlock_gradual(tdb, ltype, flags, TDB1_FREELIST_TOP, - tdb->header.hash_size * 4) == -1) { + ecode = tdb_lock_gradual(tdb, ltype, flags | TDB_LOCK_NOCHECK, + TDB1_FREELIST_TOP, tdb->header.hash_size * 4); + if (ecode != TDB_SUCCESS) { + tdb->last_error = ecode; return -1; } @@ -562,6 +304,8 @@ int tdb1_allrecord_lock(struct tdb1_context *tdb, int ltype, return -1; } + /* FIXME: Temporary cast. */ + tdb->file->allrecord_lock.owner = (void *)(struct tdb1_context *)tdb; tdb->file->allrecord_lock.count = 1; /* If it's upgradable, it's actually exclusive so we can treat * it as a write lock. */