New attempt at TDB transaction nesting allow/disallow.

[samba.git] / lib / tdb / common / transaction.c

diff --git a/lib/tdb/common/transaction.c b/lib/tdb/common/transaction.c
index e97fe67b4e02781641af95e2d63ad8293804d32e..501cd62b96ee367626f148f24eebbfd07a5de3b2 100644 (file)
--- a/lib/tdb/common/transaction.c
+++ b/lib/tdb/common/transaction.c
@@ -85,6 +85,13 @@
     still available, but no transaction recovery area is used and no
     fsync/msync calls are made.
 
+  - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
+    tdb_add_flags() transaction is enabled.
+    The default is that transaction nesting is not allowed and an attempt
+    to create a nested transaction will fail with TDB_ERR_NESTING.
+
+    Beware. when transactions are nested a transaction successfully
+    completed with tdb_transaction_commit() can be silently unrolled later.
 */
 
 
@@ -137,14 +144,6 @@ static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
 {
        uint32_t blk;
 
-       /* Only a commit is allowed on a prepared transaction */
-       if (tdb->transaction->prepared) {
-               tdb->ecode = TDB_ERR_EINVAL;
-               TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: transaction already prepared, read not allowed\n"));
-               tdb->transaction->transaction_error = 1;
-               return -1;
-       }
-
        /* break it down into block sized ops */
        while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
                tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
@@ -380,7 +379,8 @@ static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
        if (len <= tdb->map_size) {
                return 0;
        }
-       return TDB_ERRCODE(TDB_ERR_IO, -1);
+       tdb->ecode = TDB_ERR_IO;
+       return -1;
 }
 
 /*
@@ -434,6 +434,10 @@ int tdb_transaction_start(struct tdb_context *tdb)
 
        /* cope with nested tdb_transaction_start() calls */
        if (tdb->transaction != NULL) {
+               if (!(tdb->flags & TDB_ALLOW_NESTING)) {
+                       tdb->ecode = TDB_ERR_NESTING;
+                       return -1;
+               }
                tdb->transaction->nesting++;
                TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", 
                         tdb->transaction->nesting));
@@ -510,6 +514,8 @@ int tdb_transaction_start(struct tdb_context *tdb)
        tdb->transaction->io_methods = tdb->methods;
        tdb->methods = &transaction_methods;
 
+       /* Trace at the end, so we get sequence number correct. */
+       tdb_trace(tdb, "tdb_transaction_start");
        return 0;
        
 fail:
@@ -552,10 +558,7 @@ static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t
 }
 
 
-/*
-  cancel the current transaction
-*/
-int tdb_transaction_cancel(struct tdb_context *tdb)
+int _tdb_transaction_cancel(struct tdb_context *tdb)
 {      
        int i, ret = 0;
 
@@ -620,6 +623,14 @@ int tdb_transaction_cancel(struct tdb_context *tdb)
        return ret;
 }
 
+/*
+  cancel the current transaction
+*/
+int tdb_transaction_cancel(struct tdb_context *tdb)
+{
+       tdb_trace(tdb, "tdb_transaction_cancel");
+       return _tdb_transaction_cancel(tdb);
+}
 
 /*
   work out how much space the linearised recovery data will consume
@@ -657,7 +668,7 @@ static int tdb_recovery_allocate(struct tdb_context *tdb,
                                 tdb_off_t *recovery_offset,
                                 tdb_len_t *recovery_max_size)
 {
-       struct list_struct rec;
+       struct tdb_record rec;
        const struct tdb_methods *methods = tdb->transaction->io_methods;
        tdb_off_t recovery_head;
 
@@ -743,7 +754,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
        tdb_len_t recovery_size;
        unsigned char *data, *p;
        const struct tdb_methods *methods = tdb->transaction->io_methods;
-       struct list_struct *rec;
+       struct tdb_record *rec;
        tdb_off_t recovery_offset, recovery_max_size;
        tdb_off_t old_map_size = tdb->transaction->old_map_size;
        uint32_t magic, tailer;
@@ -763,7 +774,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
                return -1;
        }
 
-       rec = (struct list_struct *)data;
+       rec = (struct tdb_record *)data;
        memset(rec, 0, sizeof(*rec));
 
        rec->magic    = 0;
@@ -846,7 +857,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
        magic = TDB_RECOVERY_MAGIC;
        CONVERT(magic);
 
-       *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
+       *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
 
        if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
@@ -867,10 +878,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
        return 0;
 }
 
-/*
-  prepare to commit the current transaction
-*/
-int tdb_transaction_prepare_commit(struct tdb_context *tdb)
+static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 {      
        const struct tdb_methods *methods;
 
@@ -881,14 +889,14 @@ int tdb_transaction_prepare_commit(struct tdb_context *tdb)
 
        if (tdb->transaction->prepared) {
                tdb->ecode = TDB_ERR_EINVAL;
-               tdb_transaction_cancel(tdb);
+               _tdb_transaction_cancel(tdb);
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
                return -1;
        }
 
        if (tdb->transaction->transaction_error) {
                tdb->ecode = TDB_ERR_IO;
-               tdb_transaction_cancel(tdb);
+               _tdb_transaction_cancel(tdb);
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
                return -1;
        }
@@ -910,7 +918,7 @@ int tdb_transaction_prepare_commit(struct tdb_context *tdb)
        if (tdb->num_locks || tdb->global_lock.count) {
                tdb->ecode = TDB_ERR_LOCK;
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
-               tdb_transaction_cancel(tdb);
+               _tdb_transaction_cancel(tdb);
                return -1;
        }
 
@@ -918,7 +926,7 @@ int tdb_transaction_prepare_commit(struct tdb_context *tdb)
        if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
                tdb->ecode = TDB_ERR_LOCK;
-               tdb_transaction_cancel(tdb);
+               _tdb_transaction_cancel(tdb);
                return -1;
        }
 
@@ -927,7 +935,7 @@ int tdb_transaction_prepare_commit(struct tdb_context *tdb)
        if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
                tdb->ecode = TDB_ERR_LOCK;
-               tdb_transaction_cancel(tdb);
+               _tdb_transaction_cancel(tdb);
                return -1;
        }
 
@@ -936,7 +944,7 @@ int tdb_transaction_prepare_commit(struct tdb_context *tdb)
                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_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-                       tdb_transaction_cancel(tdb);
+                       _tdb_transaction_cancel(tdb);
                        return -1;
                }
        }
@@ -951,7 +959,7 @@ int tdb_transaction_prepare_commit(struct tdb_context *tdb)
                        tdb->ecode = TDB_ERR_IO;
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
                        tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-                       tdb_transaction_cancel(tdb);
+                       _tdb_transaction_cancel(tdb);
                        return -1;
                }
                tdb->map_size = tdb->transaction->old_map_size;
@@ -963,6 +971,15 @@ int tdb_transaction_prepare_commit(struct tdb_context *tdb)
        return 0;
 }
 
+/*
+   prepare to commit the current transaction
+*/
+int tdb_transaction_prepare_commit(struct tdb_context *tdb)
+{      
+       tdb_trace(tdb, "tdb_transaction_prepare_commit");
+       return _tdb_transaction_prepare_commit(tdb);
+}
+
 /*
   commit the current transaction
 */
@@ -977,9 +994,11 @@ int tdb_transaction_commit(struct tdb_context *tdb)
                return -1;
        }
 
+       tdb_trace(tdb, "tdb_transaction_commit");
+
        if (tdb->transaction->transaction_error) {
                tdb->ecode = TDB_ERR_IO;
-               tdb_transaction_cancel(tdb);
+               _tdb_transaction_cancel(tdb);
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
                return -1;
        }
@@ -992,12 +1011,12 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 
        /* check for a null transaction */
        if (tdb->transaction->blocks == NULL) {
-               tdb_transaction_cancel(tdb);
+               _tdb_transaction_cancel(tdb);
                return 0;
        }
 
        if (!tdb->transaction->prepared) {
-               int ret = tdb_transaction_prepare_commit(tdb);
+               int ret = _tdb_transaction_prepare_commit(tdb);
                if (ret)
                        return ret;
        }
@@ -1028,7 +1047,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
                        tdb->methods = methods;
                        tdb_transaction_recover(tdb); 
 
-                       tdb_transaction_cancel(tdb);
+                       _tdb_transaction_cancel(tdb);
                        tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
 
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
@@ -1066,7 +1085,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 
        /* use a transaction cancel to free memory and remove the
           transaction locks */
-       tdb_transaction_cancel(tdb);
+       _tdb_transaction_cancel(tdb);
 
        if (need_repack) {
                return tdb_repack(tdb);
@@ -1086,7 +1105,7 @@ int tdb_transaction_recover(struct tdb_context *tdb)
        tdb_off_t recovery_head, recovery_eof;
        unsigned char *data, *p;
        uint32_t zero = 0;
-       struct list_struct rec;
+       struct tdb_record rec;
 
        /* find the recovery area */
        if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
@@ -1173,7 +1192,7 @@ int tdb_transaction_recover(struct tdb_context *tdb)
        }
 
        /* remove the recovery magic */
-       if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic), 
+       if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
                          &zero) == -1) {
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
                tdb->ecode = TDB_ERR_IO;