tdb: use tdb_nest_lock() for open lock.
[ccan] / ccan / tdb / transaction.c
index 742f188f500dbd4bba8dcbe4f6d080a2663ca7ab..ded3fa836fc721a07932c54a6f741b89c8329066 100644 (file)
@@ -76,7 +76,7 @@
     to reduce this to 3 or even 2 with some more work.
 
   - check for a valid recovery record on open of the tdb, while the
-    global lock is held. Automatically recover from the transaction
+    open lock is held. Automatically recover from the transaction
     recovery area if needed, then continue with the open as
     usual. This allows for smooth crash recovery with no administrator
     intervention.
@@ -415,6 +415,9 @@ static int transaction_brlock(struct tdb_context *tdb,
                              int rw_type, tdb_off_t offset, size_t len,
                              enum tdb_lock_flags flags)
 {
+       /* FIXME: We actually grab the open lock during a transaction. */
+       if (offset == OPEN_LOCK)
+               return tdb_brlock(tdb, rw_type, offset, len, flags);
        return 0;
 }
 
@@ -491,33 +494,18 @@ int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
 
        if (tdb->transaction->magic_offset) {
                const struct tdb_methods *methods = tdb->transaction->io_methods;
-               uint32_t zero = 0;
+               uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
 
                /* remove the recovery marker */
-               if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
+               if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
                transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
                        ret = -1;
                }
        }
 
-       /* remove any global lock created during the transaction */
-       if (tdb->global_lock.count != 0) {
-               tdb_brunlock(tdb, tdb->global_lock.ltype,
-                            FREELIST_TOP, 4*tdb->header.hash_size);
-               tdb->global_lock.count = 0;
-       }
-
-       /* remove any locks created during the transaction */
-       if (tdb->num_locks != 0) {
-               for (i=0;i<tdb->num_lockrecs;i++) {
-                       tdb_brunlock(tdb, tdb->lockrecs[i].ltype,
-                                    FREELIST_TOP+4*tdb->lockrecs[i].list, 1);
-               }
-               tdb->num_locks = 0;
-               tdb->num_lockrecs = 0;
-               SAFE_FREE(tdb->lockrecs);
-       }
+       /* This also removes the OPEN_LOCK, if we have it. */
+       tdb_release_extra_locks(tdb);
 
        /* restore the normal io methods */
        tdb->methods = tdb->transaction->io_methods;
@@ -556,7 +544,7 @@ int tdb_transaction_start(struct tdb_context *tdb)
                return 0;
        }
 
-       if (tdb->num_locks != 0 || tdb->global_lock.count) {
+       if (tdb_have_extra_locks(tdb)) {
                /* the caller must not have any locks when starting a
                   transaction as otherwise we'll be screwed by lack
                   of nested locks in posix */
@@ -797,7 +785,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
        rec = (struct tdb_record *)data;
        memset(rec, 0, sizeof(*rec));
 
-       rec->magic    = 0;
+       rec->magic    = TDB_RECOVERY_INVALID_MAGIC;
        rec->data_len = recovery_size;
        rec->rec_len  = recovery_max_size;
        rec->key_len  = old_map_size;
@@ -936,7 +924,7 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
        
        /* if there are any locks pending then the caller has not
           nested their locks properly, so fail the transaction */
-       if (tdb->num_locks || tdb->global_lock.count) {
+       if (tdb_have_extra_locks(tdb)) {
                tdb->ecode = TDB_ERR_LOCK;
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
                _tdb_transaction_cancel(tdb, F_RDLCK);
@@ -951,11 +939,10 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
                return -1;
        }
 
-       /* get the global lock - this prevents new users attaching to the database
+       /* get the open lock - this prevents new users attaching to the database
           during the commit */
-       if (tdb_brlock(tdb, F_WRLCK, GLOBAL_LOCK, 1, TDB_LOCK_WAIT) == -1) {
-               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
-               tdb->ecode = TDB_ERR_LOCK;
+       if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
                _tdb_transaction_cancel(tdb, F_WRLCK);
                return -1;
        }
@@ -964,7 +951,6 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
                /* write the recovery data to the end of the file */
                if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
-                       tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
                        _tdb_transaction_cancel(tdb, F_WRLCK);
                        return -1;
                }
@@ -979,7 +965,6 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
                                             tdb->transaction->old_map_size) == -1) {
                        tdb->ecode = TDB_ERR_IO;
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
-                       tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
                        _tdb_transaction_cancel(tdb, F_WRLCK);
                        return -1;
                }
@@ -987,7 +972,7 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
                methods->tdb_oob(tdb, tdb->map_size + 1, 1);
        }
 
-       /* Keep the global lock until the actual commit */
+       /* Keep the open lock until the actual commit */
 
        return 0;
 }
@@ -1069,7 +1054,6 @@ int tdb_transaction_commit(struct tdb_context *tdb)
                        tdb_transaction_recover(tdb); 
 
                        _tdb_transaction_cancel(tdb, F_WRLCK);
-                       tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
 
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
                        return -1;
@@ -1085,8 +1069,6 @@ int tdb_transaction_commit(struct tdb_context *tdb)
                return -1;
        }
 
-       tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
-
        /*
          TODO: maybe write to some dummy hdr field, or write to magic
          offset without mmap, before the last sync, instead of the
@@ -1118,7 +1100,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 
 /*
   recover from an aborted transaction. Must be called with exclusive
-  database write access already established (including the global
+  database write access already established (including the open
   lock to prevent new processes attaching)
 */
 int tdb_transaction_recover(struct tdb_context *tdb)