From d07875330a6dbf44c1d65c029af80b53e5836d2d Mon Sep 17 00:00:00 2001
From: Amitay Isaacs <amitay@gmail.com>
Date: Tue, 24 Nov 2020 13:25:04 +1100
Subject: [PATCH] ctdb-locking: Pass additional arguments to debug locks script

1. PID of lock helper waiting for lock
2. Scope of lock: "record" or "db"
3. Path to database that lock helper is trying to lock
4. Whether the database uses mutexes: "mutex" or "fcntl"

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
---
 ctdb/server/ctdb_lock.c | 61 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 5 deletions(-)

diff --git a/ctdb/server/ctdb_lock.c b/ctdb/server/ctdb_lock.c
index 478447d76f8..063ebfa07cf 100644
--- a/ctdb/server/ctdb_lock.c
+++ b/ctdb/server/ctdb_lock.c
@@ -496,6 +496,50 @@ fail:
 
 }
 
+static const char **debug_locks_args(TALLOC_CTX *mem_ctx, struct lock_context *lock_ctx)
+{
+	const char **args = NULL;
+	int tdb_flags;
+	int nargs, i;
+
+	/* Program, lock helper PID, db|record, tdb path, fcntl|mutex, NULL */
+	nargs = 6;
+
+	args = talloc_array(mem_ctx, const char *, nargs);
+	if (args == NULL) {
+		return NULL;
+	}
+
+	args[0] = talloc_strdup(args, "debug_locks");
+	args[1] = talloc_asprintf(args, "%d", lock_ctx->child);
+
+	if (lock_ctx->type == LOCK_RECORD) {
+		args[2] = talloc_strdup(args, "RECORD");
+	} else {
+		args[2] = talloc_strdup(args, "DB");
+	}
+
+	args[3] = talloc_strdup(args, lock_ctx->ctdb_db->db_path);
+
+	tdb_flags = tdb_get_flags(lock_ctx->ctdb_db->ltdb->tdb);
+	if (tdb_flags & TDB_MUTEX_LOCKING) {
+		args[4] = talloc_strdup(args, "MUTEX");
+	} else {
+		args[4] = talloc_strdup(args, "FCNTL");
+	}
+
+	args[5] = NULL;
+
+	for (i=0; i<nargs-1; i++) {
+		if (args[i] == NULL) {
+			talloc_free(args);
+			return NULL;
+		}
+	}
+
+	return args;
+}
+
 /*
  * Callback routine when required locks are not obtained within timeout
  * Called from parent context
@@ -512,6 +556,7 @@ static void ctdb_lock_timeout_handler(struct tevent_context *ev,
 	double elapsed_time;
 	bool skip;
 	char *keystr;
+	const char **args;
 
 	lock_ctx = talloc_get_type_abort(private_data, struct lock_context);
 	ctdb = lock_ctx->ctdb;
@@ -554,12 +599,18 @@ lock_debug:
 			    debug_locks, sizeof(debug_locks),
 			    "CTDB_DEBUG_LOCKS",
 			    getenv("CTDB_BASE"), "debug_locks.sh")) {
-		pid = vfork();
-		if (pid == 0) {
-			execl(debug_locks, debug_locks, NULL);
-			_exit(0);
+		args = debug_locks_args(lock_ctx, lock_ctx);
+		if (args != NULL) {
+			pid = vfork();
+			if (pid == 0) {
+				execvp(debug_locks, discard_const(args));
+				_exit(0);
+			}
+			talloc_free(args);
+			ctdb_track_child(ctdb, pid);
+		} else {
+			D_WARNING("No memory for debug locks args\n");
 		}
-		ctdb_track_child(ctdb, pid);
 	} else {
 		DEBUG(DEBUG_WARNING,
 		      (__location__
-- 
2.47.3