tdb: remove lock ops

Now the transaction code uses the standard allrecord lock, that stops
us from trying to grab any per-record locks anyway.  We don't need to
have special noop lock ops for transactions.

This is a nice simplification: if you see brlock, you know it's really
going to grab a lock.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/tdb/io.c

@@ -463,8 +463,6 @@ static const struct tdb_methods io_methods = {
 	tdb_next_hash_chain,
 	tdb_oob,
 	tdb_expand_file,
-	tdb_brlock,
-	tdb_brunlock
 };
 
 /*

ccan/tdb/lock.c

@@ -119,6 +119,12 @@ static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
 	return fcntl(tdb->fd, F_SETLKW, &fl);
 }
 
+/* list -1 is the alloc list, otherwise a hash chain. */
+static tdb_off_t lock_offset(int list)
+{
+	return FREELIST_TOP + 4*list;
+}
+
 /* a byte range locking function - return 0 on success
    this functions locks/unlocks 1 byte at the specified offset.
 
@@ -146,6 +152,14 @@ int tdb_brlock(struct tdb_context *tdb,
 		return -1;
 	}
 
+	/* Sanity check */
+	if (tdb->transaction && offset >= lock_offset(-1) && len != 0) {
+		tdb->ecode = TDB_ERR_RDONLY;
+		TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_brlock attempted in transaction at offset %d rw_type=%d flags=%d len=%d\n",
+			 offset, rw_type, flags, (int)len));
+		return -1;
+	}
+
 	do {
 		ret = fcntl_lock(tdb, rw_type, offset, len,
 				 flags & TDB_LOCK_WAIT);
@@ -234,12 +248,6 @@ int tdb_allrecord_upgrade(struct tdb_context *tdb)
 	return -1;
 }
 
-/* list -1 is the alloc list, otherwise a hash chain. */
-static tdb_off_t lock_offset(int list)
-{
-	return FREELIST_TOP + 4*list;
-}
-
 static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
 					   tdb_off_t offset)
 {
@@ -289,7 +297,7 @@ int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
 
 	/* Since fcntl locks don't nest, we do a lock for the first one,
 	   and simply bump the count for future ones */
-	if (tdb->methods->brlock(tdb, ltype, offset, 1, flags)) {
+	if (tdb_brlock(tdb, ltype, offset, 1, flags)) {
 		return -1;
 	}
 
@@ -380,7 +388,7 @@ int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
 	if (mark_lock) {
 		ret = 0;
 	} else {
-		ret = tdb->methods->brunlock(tdb, ltype, offset, 1);
+		ret = tdb_brunlock(tdb, ltype, offset, 1);
 	}
 
 	/*
@@ -470,7 +478,7 @@ int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
 		return -1;
 	}
 
-	if (tdb->methods->brlock(tdb, ltype, FREELIST_TOP, 0, flags)) {
+	if (tdb_brlock(tdb, ltype, FREELIST_TOP, 0, flags)) {
 		if (flags & TDB_LOCK_WAIT) {
 			TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lockall failed (%s)\n", strerror(errno)));
 		}
@@ -514,8 +522,7 @@ int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock)
 		return 0;
 	}
 
-	if (!mark_lock &&
-	    tdb->methods->brunlock(tdb, ltype, FREELIST_TOP, 0)) {
+	if (!mark_lock && tdb_brunlock(tdb, ltype, FREELIST_TOP, 0)) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno)));
 		return -1;
 	}
@@ -648,7 +655,7 @@ int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
 	if (tdb->allrecord_lock.count) {
 		return 0;
 	}
-	return off ? tdb->methods->brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
+	return off ? tdb_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
 }
 
 /*
@@ -668,7 +675,7 @@ int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
 		}
 		return -1;
 	}
-	return tdb->methods->brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
+	return tdb_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
 }
 
 int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
@@ -676,7 +683,7 @@ int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
 	if (tdb->allrecord_lock.count) {
 		return 0;
 	}
-	return tdb->methods->brunlock(tdb, F_WRLCK, off, 1);
+	return tdb_brunlock(tdb, F_WRLCK, off, 1);
 }
 
 /* fcntl locks don't stack: avoid unlocking someone else's */
@@ -694,7 +701,7 @@ int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
 	for (i = &tdb->travlocks; i; i = i->next)
 		if (i->off == off)
 			count++;
-	return (count == 1 ? tdb->methods->brunlock(tdb, F_RDLCK, off, 1) : 0);
+	return (count == 1 ? tdb_brunlock(tdb, F_RDLCK, off, 1) : 0);
 }
 
 bool tdb_have_extra_locks(struct tdb_context *tdb)

ccan/tdb/tdb_private.h

@@ -211,8 +211,6 @@ struct tdb_methods {
 	void (*next_hash_chain)(struct tdb_context *, uint32_t *);
 	int (*tdb_oob)(struct tdb_context *, tdb_off_t , int );
 	int (*tdb_expand_file)(struct tdb_context *, tdb_off_t , tdb_off_t );
-	int (*brlock)(struct tdb_context *, int, tdb_off_t, size_t, enum tdb_lock_flags);
-	int (*brunlock)(struct tdb_context *, int, tdb_off_t, size_t);
 };
 
 struct tdb_context {

ccan/tdb/test/run-3G-file.c

@@ -50,9 +50,7 @@ static const struct tdb_methods large_io_methods = {
 	tdb_write,
 	tdb_next_hash_chain,
 	tdb_oob,
-	tdb_expand_file_sparse,
-	tdb_brlock,
-	tdb_brunlock
+	tdb_expand_file_sparse
 };
 
 static int test_traverse(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data,

ccan/tdb/transaction.c

@@ -408,33 +408,12 @@ static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
 	return 0;
 }
 
-/*
-  brlock during a transaction - ignore them
-*/
-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;
-}
-
-static int transaction_brunlock(struct tdb_context *tdb,
-				int rw_type, tdb_off_t offset, size_t len)
-{
-	return 0;
-}
-
 static const struct tdb_methods transaction_methods = {
 	transaction_read,
 	transaction_write,
 	transaction_next_hash_chain,
 	transaction_oob,
 	transaction_expand_file,
-	transaction_brlock,
-	transaction_brunlock
 };
 
 /*