1 files changed, 95 insertions, 0 deletions
diff --git a/module/zfs/zfs_debug.c b/module/zfs/zfs_debug.c
new file mode 100644
index 000000000..d0f411a99
--- /dev/null
+++ b/module/zfs/zfs_debug.c
@@ -0,0 +1,95 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ */
+
+#include <sys/zfs_context.h>
+
+list_t zfs_dbgmsgs;
+int zfs_dbgmsg_size;
+kmutex_t zfs_dbgmsgs_lock;
+int zfs_dbgmsg_maxsize = 1<<20; /* 1MB */
+
+void
+zfs_dbgmsg_init(void)
+{
+	list_create(&zfs_dbgmsgs, sizeof (zfs_dbgmsg_t),
+	    offsetof(zfs_dbgmsg_t, zdm_node));
+	mutex_init(&zfs_dbgmsgs_lock, NULL, MUTEX_DEFAULT, NULL);
+}
+
+void
+zfs_dbgmsg_fini(void)
+{
+	zfs_dbgmsg_t *zdm;
+
+	while ((zdm = list_remove_head(&zfs_dbgmsgs)) != NULL) {
+		int size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
+		kmem_free(zdm, size);
+		zfs_dbgmsg_size -= size;
+	}
+	mutex_destroy(&zfs_dbgmsgs_lock);
+	ASSERT3U(zfs_dbgmsg_size, ==, 0);
+}
+
+/*
+ * Print these messages by running:
+ * 	echo ::zfs_dbgmsg | mdb -k
+ *
+ * Monitor these messages by running:
+ * 	dtrace -q -n 'zfs-dbgmsg{printf("%s\n", stringof(arg0))}'
+ */
+void
+zfs_dbgmsg(const char *fmt, ...)
+{
+	int size;
+	va_list adx;
+	zfs_dbgmsg_t *zdm;
+
+	va_start(adx, fmt);
+	size = vsnprintf(NULL, 0, fmt, adx);
+	va_end(adx);
+
+	/*
+	 * There is one byte of string in sizeof (zfs_dbgmsg_t), used
+	 * for the terminating null.
+	 */
+	zdm = kmem_alloc(sizeof (zfs_dbgmsg_t) + size, KM_SLEEP);
+	zdm->zdm_timestamp = gethrestime_sec();
+
+	va_start(adx, fmt);
+	(void) vsnprintf(zdm->zdm_msg, size + 1, fmt, adx);
+	va_end(adx);
+
+	DTRACE_PROBE1(zfs__dbgmsg, char *, zdm->zdm_msg);
+
+	mutex_enter(&zfs_dbgmsgs_lock);
+	list_insert_tail(&zfs_dbgmsgs, zdm);
+	zfs_dbgmsg_size += sizeof (zfs_dbgmsg_t) + size;
+	while (zfs_dbgmsg_size > zfs_dbgmsg_maxsize) {
+		zdm = list_remove_head(&zfs_dbgmsgs);
+		size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
+		kmem_free(zdm, size);
+		zfs_dbgmsg_size -= size;
+	}
+	mutex_exit(&zfs_dbgmsgs_lock);
+}