tdb: tdb_allrecord_lock/tdb_allrecord_unlock/tdb_allrecord_upgrade

Centralize locking of all chains of the tdb; rename _tdb_lockall to
tdb_allrecord_lock and _tdb_unlockall to tdb_allrecord_unlock, and
tdb_brlock_upgrade to tdb_allrecord_upgrade.

Then we use this in the transaction code.  Unfortunately, if the transaction
code records that it has grabbed the allrecord lock read-only, write locks
will fail, so we treat this upgradable lock as a write lock, and mark it
as upgradable using the otherwise-unused offset field.

One subtlety: now the transaction code is using the allrecord_lock, the
tdb_release_extra_locks() function drops it for us, so we no longer need
to do it manually in _tdb_transaction_cancel.

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

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/tdb/common/tdb_private.h b/lib/tdb/common/tdb_private.h
index 0ac37dfa5d..013c2f022e 100644
--- a/lib/tdb/common/tdb_private.h
+++ b/lib/tdb/common/tdb_private.h
@@ -191,7 +191,7 @@ struct tdb_context {
 	int read_only; /* opened read-only */
 	int traverse_read; /* read-only traversal */
 	int traverse_write; /* read-write traversal */
-	struct tdb_lock_type allrecord_lock;
+	struct tdb_lock_type allrecord_lock; /* .offset == upgradable */
 	int num_lockrecs;
 	struct tdb_lock_type *lockrecs; /* only real locks, all with count>0 */
 	enum TDB_ERROR ecode; /* error code for last tdb error */
@@ -236,7 +236,10 @@ bool tdb_have_extra_locks(struct tdb_context *tdb);
 void tdb_release_extra_locks(struct tdb_context *tdb);
 int tdb_transaction_lock(struct tdb_context *tdb, int ltype);
 int tdb_transaction_unlock(struct tdb_context *tdb, int ltype);
-int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len);
+int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
+		       enum tdb_lock_flags flags, bool upgradable);
+int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock);
+int tdb_allrecord_upgrade(struct tdb_context *tdb);
 int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off);
 int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off);
 int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d);