1 files changed, 112 insertions, 0 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/rrwlock.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/rrwlock.h
new file mode 100644
index 000000000000..a1844f01aa2b
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/rrwlock.h
@@ -0,0 +1,112 @@
+/*
+ * 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 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+/*
+ * Copyright (c) 2012 by Delphix. All rights reserved.
+ */
+
+#ifndef	_SYS_RR_RW_LOCK_H
+#define	_SYS_RR_RW_LOCK_H
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+#include <sys/zfs_context.h>
+#include <sys/refcount.h>
+
+/*
+ * A reader-writer lock implementation that allows re-entrant reads, but
+ * still gives writers priority on "new" reads.
+ *
+ * See rrwlock.c for more details about the implementation.
+ *
+ * Fields of the rrwlock_t structure:
+ * - rr_lock: protects modification and reading of rrwlock_t fields
+ * - rr_cv: cv for waking up readers or waiting writers
+ * - rr_writer: thread id of the current writer
+ * - rr_anon_rount: number of active anonymous readers
+ * - rr_linked_rcount: total number of non-anonymous active readers
+ * - rr_writer_wanted: a writer wants the lock
+ */
+typedef struct rrwlock {
+	kmutex_t	rr_lock;
+	kcondvar_t	rr_cv;
+	kthread_t	*rr_writer;
+	refcount_t	rr_anon_rcount;
+	refcount_t	rr_linked_rcount;
+	boolean_t	rr_writer_wanted;
+	boolean_t	rr_track_all;
+} rrwlock_t;
+
+/*
+ * 'tag' is used in reference counting tracking.  The
+ * 'tag' must be the same in a rrw_enter() as in its
+ * corresponding rrw_exit().
+ */
+void rrw_init(rrwlock_t *rrl, boolean_t track_all);
+void rrw_destroy(rrwlock_t *rrl);
+void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag);
+void rrw_enter_read(rrwlock_t *rrl, void *tag);
+void rrw_enter_read_prio(rrwlock_t *rrl, void *tag);
+void rrw_enter_write(rrwlock_t *rrl);
+void rrw_exit(rrwlock_t *rrl, void *tag);
+boolean_t rrw_held(rrwlock_t *rrl, krw_t rw);
+void rrw_tsd_destroy(void *arg);
+
+#define	RRW_READ_HELD(x)	rrw_held(x, RW_READER)
+#define	RRW_WRITE_HELD(x)	rrw_held(x, RW_WRITER)
+#define	RRW_LOCK_HELD(x) \
+	(rrw_held(x, RW_WRITER) || rrw_held(x, RW_READER))
+
+/*
+ * A reader-mostly lock implementation, tuning above reader-writer locks
+ * for hightly parallel read acquisitions, pessimizing write acquisitions.
+ *
+ * This should be a prime number.  See comment in rrwlock.c near
+ * RRM_TD_LOCK() for details.
+ */
+#define	RRM_NUM_LOCKS		17
+typedef struct rrmlock {
+	rrwlock_t	locks[RRM_NUM_LOCKS];
+} rrmlock_t;
+
+void rrm_init(rrmlock_t *rrl, boolean_t track_all);
+void rrm_destroy(rrmlock_t *rrl);
+void rrm_enter(rrmlock_t *rrl, krw_t rw, void *tag);
+void rrm_enter_read(rrmlock_t *rrl, void *tag);
+void rrm_enter_write(rrmlock_t *rrl);
+void rrm_exit(rrmlock_t *rrl, void *tag);
+boolean_t rrm_held(rrmlock_t *rrl, krw_t rw);
+
+#define	RRM_READ_HELD(x)	rrm_held(x, RW_READER)
+#define	RRM_WRITE_HELD(x)	rrm_held(x, RW_WRITER)
+#define	RRM_LOCK_HELD(x) \
+	(rrm_held(x, RW_WRITER) || rrm_held(x, RW_READER))
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif	/* _SYS_RR_RW_LOCK_H */