tdb: use tdb_nest_lock() for open lock.

This never nests, so it's overkill, but it centralizes the locking into
lock.c and removes the ugly flag in the transaction code to track whether
we have the lock or not.

Note that we have a temporary hack so this places a real lock, despite
the fact that we are in a transaction.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/ccan/tdb/lock.c b/ccan/tdb/lock.c
index 870601126bdb82d72163f3aba5b0f76f66c5c86e..6f5799a8198f13dd06851aae03869c635035200e 100644 (file)
--- a/ccan/tdb/lock.c
+++ b/ccan/tdb/lock.c
@@ -683,7 +683,8 @@ bool tdb_have_extra_locks(struct tdb_context *tdb)
        return extra;
 }
 
-/* The transaction code uses this to remove all locks. */
+/* The transaction code uses this to remove all locks.  Note that this
+   may include OPEN_LOCK. */
 void tdb_release_extra_locks(struct tdb_context *tdb)
 {
        unsigned int i, extra = 0;

diff --git a/ccan/tdb/open.c b/ccan/tdb/open.c
index b7aa6e745e0aa388b6162b63952137be3a047b2f..54a8fe57ad11a460471785dbf370f7ae1f4a9b93 100644 (file)
--- a/ccan/tdb/open.c
+++ b/ccan/tdb/open.c
@@ -240,7 +240,7 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 
        /* ensure there is only one process initialising at once */
-       if (tdb->methods->brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT) == -1) {
+       if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to get open lock on %s: %s\n",
                         name, strerror(errno)));
                goto fail;      /* errno set by tdb_brlock */
@@ -356,8 +356,9 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
        /* Internal (memory-only) databases skip all the code above to
         * do with disk files, and resume here by releasing their
         * open lock and hooking into the active list. */
-       if (tdb->methods->brunlock(tdb, F_WRLCK, OPEN_LOCK, 1) == -1)
+       if (tdb_nest_unlock(tdb, OPEN_LOCK, F_WRLCK, false) == -1) {
                goto fail;
+       }
        tdb->next = tdbs;
        tdbs = tdb;
        return tdb;

diff --git a/ccan/tdb/transaction.c b/ccan/tdb/transaction.c
index 81103ed8a019bf441a7b85353c23db61c7489744..ded3fa836fc721a07932c54a6f741b89c8329066 100644 (file)
--- a/ccan/tdb/transaction.c
+++ b/ccan/tdb/transaction.c
@@ -135,9 +135,6 @@ struct tdb_transaction {
        bool prepared;
        tdb_off_t magic_offset;
 
-       /* set when the OPEN_LOCK has been taken */
-       bool open_lock_taken;
-
        /* old file size before transaction */
        tdb_len_t old_map_size;
 
@@ -418,6 +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;
 }
 
@@ -504,11 +504,7 @@ int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
                }
        }
 
-       if (tdb->transaction->open_lock_taken) {
-               tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1);
-               tdb->transaction->open_lock_taken = false;
-       }
-
+       /* This also removes the OPEN_LOCK, if we have it. */
        tdb_release_extra_locks(tdb);
 
        /* restore the normal io methods */
@@ -945,15 +941,12 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 
        /* get the open lock - this prevents new users attaching to the database
           during the commit */
-       if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT) == -1) {
+       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->ecode = TDB_ERR_LOCK;
                _tdb_transaction_cancel(tdb, F_WRLCK);
                return -1;
        }
 
-       tdb->transaction->open_lock_taken = true;
-
        if (!(tdb->flags & TDB_NOSYNC)) {
                /* write the recovery data to the end of the file */
                if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {