1 files changed, 99 insertions, 0 deletions
diff --git a/module/zfs/zfs_ratelimit.c b/module/zfs/zfs_ratelimit.c
new file mode 100644
index 000000000..d4a7d5217
--- /dev/null
+++ b/module/zfs/zfs_ratelimit.c
@@ -0,0 +1,99 @@
+/*
+ * 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) 2017, Lawrence Livermore National Security, LLC.
+ */
+
+#include <sys/zfs_ratelimit.h>
+
+/*
+ * Initialize rate limit struct
+ *
+ * rl:		zfs_ratelimit_t struct
+ * burst:	Number to allow in an interval before rate limiting
+ * interval:	Interval time in seconds
+ */
+void
+zfs_ratelimit_init(zfs_ratelimit_t *rl, unsigned int burst,
+    unsigned int interval)
+{
+	rl->count = 0;
+	rl->start = 0;
+	rl->interval = interval;
+	rl->burst = burst;
+	mutex_init(&rl->lock, NULL, MUTEX_DEFAULT, NULL);
+}
+
+/*
+ * Finalize rate limit struct
+ *
+ * rl:		zfs_ratelimit_t struct
+ */
+void
+zfs_ratelimit_fini(zfs_ratelimit_t *rl)
+{
+	mutex_destroy(&rl->lock);
+}
+
+/*
+ * Re-implementation of the kernel's __ratelimit() function
+ *
+ * We had to write our own rate limiter because the kernel's __ratelimit()
+ * function annoyingly prints out how many times it rate limited to the kernel
+ * logs (and there's no way to turn it off):
+ *
+ *	__ratelimit: 59 callbacks suppressed
+ *
+ * If the kernel ever allows us to disable these prints, we should go back to
+ * using __ratelimit() instead.
+ *
+ * Return values are the same as __ratelimit():
+ *
+ * 0: If we're rate limiting
+ * 1: If we're not rate limiting.
+ */
+int
+zfs_ratelimit(zfs_ratelimit_t *rl)
+{
+	hrtime_t now;
+
+	hrtime_t elapsed;
+	int error = 1;
+
+	mutex_enter(&rl->lock);
+
+	now = gethrtime();
+	elapsed = now - rl->start;
+
+	rl->count++;
+	if (NSEC2SEC(elapsed) >= rl->interval) {
+		rl->start = now;
+		rl->count = 0;
+	} else {
+		if (rl->count >= rl->burst) {
+			error = 0; /* We're ratelimiting */
+		}
+	}
+	mutex_exit(&rl->lock);
+
+	return (error);
+}