Update singlenode locking

Support lock conversion
Work also with LCK_READ
TODO: do more validation.

2 files changed, 60 insertions, 64 deletions

diff --git a/WHATS_NEW b/WHATS_NEW
index 66057376..c40ced34 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.96 - 
 ================================
+  Improve clmvd singlenode locking for better testing.
   Update and correct lvs man page with supported column names.
   Handle replacement of an active device that goes missing with an error device.
   Change change raid1 segtype always to request a flush when suspending.
diff --git a/daemons/clvmd/clvmd-singlenode.c b/daemons/clvmd/clvmd-singlenode.c
index e75de98e..298abcb2 100644
--- a/daemons/clvmd/clvmd-singlenode.c
+++ b/daemons/clvmd/clvmd-singlenode.c
@@ -28,8 +28,15 @@
 
 static const char SINGLENODE_CLVMD_SOCKNAME[] = DEFAULT_RUN_DIR "/clvmd_singlenode.sock";
 static int listen_fd = -1;
-static int *_locks = NULL;
-static char **_resources = NULL;
+
+static struct dm_hash_table *_locks;
+static int _lockid;
+
+struct lock {
+	int lockid;
+	int mode;
+	int excl;
+};
 
 static void close_comms(void)
 {
@@ -88,9 +95,16 @@ static int _init_cluster(void)
 {
 	int r;
 
+	if (!(_locks = dm_hash_create(128))) {
+		DEBUGLOG("Failed to allocate single-node hash table.\n");
+		return 1;
+	}
+
 	r = init_comms();
-	if (r)
+	if (r) {
+		dm_hash_destroy(_locks);
 		return r;
+	}
 
 	DEBUGLOG("Single-node cluster initialised.\n");
 	return 0;
@@ -102,10 +116,9 @@ static void _cluster_closedown(void)
 
 	DEBUGLOG("cluster_closedown\n");
 	destroy_lvhash();
-	dm_free(_locks);
-	dm_free(_resources);
+	dm_hash_destroy(_locks);
 	_locks = NULL;
-	_resources = NULL;
+	_lockid = 0;
 }
 
 static void _get_our_csid(char *csid)
@@ -145,7 +158,6 @@ static int _cluster_do_node_callback(struct local_client *master_client,
 
 int _lock_file(const char *file, uint32_t flags);
 
-static int _lock_max = 1;
 static pthread_mutex_t _lock_mutex = PTHREAD_MUTEX_INITIALIZER;
 /* Using one common condition for all locks for simplicity */
 static pthread_cond_t _lock_cond = PTHREAD_COND_INITIALIZER;
@@ -153,66 +165,46 @@ static pthread_cond_t _lock_cond = PTHREAD_COND_INITIALIZER;
 /* Real locking */
 static int _lock_resource(const char *resource, int mode, int flags, int *lockid)
 {
-	int *_locks_1;
-	char **_resources_1;
-	int i, j;
-
-	if (mode == LCK_READ) { /* only track PREAD, aka PROTECTED READ */
-		DEBUGLOG("Not tracking CONCURRENT READ lock: %s, flags=%d, mode=%d\n",
-			 resource, flags, mode);
-		*lockid = -1;
-		return 0;
-	}
+	struct lock *lck;
 
 	DEBUGLOG("Locking resource %s, flags=%d, mode=%d\n",
 		 resource, flags, mode);
 
+	mode &= LCK_TYPE_MASK;
 	pthread_mutex_lock(&_lock_mutex);
 retry:
-
-	/* look for an existing lock for this resource */
-	for (i = 1; i < _lock_max; ++i) {
-		if (!_resources[i])
-			break;
-		if (!strcmp(_resources[i], resource)) {
-			if ((_locks[i] & LCK_TYPE_MASK) == LCK_WRITE ||
-			    (_locks[i] & LCK_TYPE_MASK) == LCK_EXCL) {
-				DEBUGLOG("Resource %s already write/exclusively locked...\n", resource);
-				goto maybe_retry;
-			}
-			if ((mode & LCK_TYPE_MASK) == LCK_WRITE ||
-			    (mode & LCK_TYPE_MASK) == LCK_EXCL) {
-				DEBUGLOG("Resource %s already locked and WRITE/EXCL lock requested...\n",
-					 resource);
-				goto maybe_retry;
-			}
-		}
+	if (!(lck = dm_hash_lookup(_locks, resource))) {
+		/* Add new locked resource */
+		if (!(lck = dm_zalloc(sizeof(struct lock))) ||
+		    !dm_hash_insert(_locks, resource, lck))
+			goto bad;
+
+		lck->lockid = ++_lockid;
+		goto out;
 	}
 
-	if (i == _lock_max) { /* out of lock slots, extend */
-		if (!(_locks_1 = dm_realloc(_locks, 2 * _lock_max * sizeof(int))))
-			goto_bad;
-
-		_locks = _locks_1;
-		if (!(_resources_1 = dm_realloc(_resources, 2 * _lock_max * sizeof(char *))))
-			/* _locks may get realloc'd twice, but that should be safe */
-			goto_bad;
-
-		_resources = _resources_1;
-		/* clear the new resource entries */
-		for (j = _lock_max; j < 2 * _lock_max; ++j)
-			_resources[j] = NULL;
-		_lock_max = 2 * _lock_max;
+        /* Update/convert lock */
+	if (flags == LCKF_CONVERT) {
+		if (lck->excl)
+			mode = LCK_EXCL;
+	} else if ((lck->mode == LCK_WRITE) || (lck->mode == LCK_EXCL)) {
+		DEBUGLOG("Resource %s already %s locked (%d)...\n", resource,
+			 (lck->mode == LCK_WRITE) ? "write" : "exclusively", lck->lockid);
+		goto maybe_retry;
+	} else if (lck->mode > mode) {
+		DEBUGLOG("Resource %s already locked and %s lock requested...\n",
+			 resource,
+			 (mode == LCK_READ) ? "READ" :
+			 (mode == LCK_WRITE) ? "WRITE" : "EXCLUSIVE");
+		goto maybe_retry;
 	}
 
-	/* resource is not currently locked, grab it */
-	if (!(_resources[i] = dm_strdup(resource)))
-		goto_bad;
-
-	*lockid = i;
-	_locks[i] = mode;
-
-	DEBUGLOG("Locked resource %s, lockid=%d\n", resource, i);
+out:
+	*lockid = lck->lockid;
+	lck->mode = mode;
+	lck->excl |= (mode == LCK_EXCL);
+	DEBUGLOG("Locked resource %s, lockid=%d, mode=%d\n", resource, lck->lockid, mode);
+	pthread_cond_broadcast(&_lock_cond); /* wakeup waiters */
 	pthread_mutex_unlock(&_lock_mutex);
 
 	return 0;
@@ -220,6 +212,7 @@ retry:
 maybe_retry:
 	if (!(flags & LCK_NONBLOCK)) {
 		pthread_cond_wait(&_lock_cond, &_lock_mutex);
+		DEBUGLOG("Resource %s RETRYING lock...\n", resource);
 		goto retry;
 	}
 bad:
@@ -231,6 +224,8 @@ bad:
 
 static int _unlock_resource(const char *resource, int lockid)
 {
+	struct lock *lck;
+
 	if (lockid < 0) {
 		DEBUGLOG("Not tracking unlock of lockid -1: %s, lockid=%d\n",
 			 resource, lockid);
@@ -240,21 +235,21 @@ static int _unlock_resource(const char *resource, int lockid)
 	DEBUGLOG("Unlocking resource %s, lockid=%d\n", resource, lockid);
 	pthread_mutex_lock(&_lock_mutex);
 
-	if (!_resources[lockid]) {
+	if (!(lck = dm_hash_lookup(_locks, resource))) {
 		pthread_mutex_unlock(&_lock_mutex);
-		DEBUGLOG("Resource %s, lockid=%d is not locked\n", resource, lockid);
+		DEBUGLOG("Resource %s, lockid=%d is not locked.\n", resource, lockid);
 		return 1;
 	}
 
-	if (strcmp(_resources[lockid], resource)) {
+	if (lck->lockid != lockid) {
 		pthread_mutex_unlock(&_lock_mutex);
-		DEBUGLOG("Resource %d has wrong resource (requested %s, got %s)\n",
-			 lockid, resource, _resources[lockid]);
+		DEBUGLOG("Resource %s has wrong lockid %d, expected %d.\n",
+			 resource, lck->lockid, lockid);
 		return 1;
 	}
 
-	dm_free(_resources[lockid]);
-	_resources[lockid] = 0;
+	dm_hash_remove(_locks, resource);
+	dm_free(lck);
 	pthread_cond_broadcast(&_lock_cond); /* wakeup waiters */
 	pthread_mutex_unlock(&_lock_mutex);