ZAP: Align za_name in zap_attribute_t to 8 bytes
[zfs.git] / include / sys / rrwlock.h
blob367732a8391c0a1a7822923c7ae77e10ccd720ed
1 /*
2 * CDDL HEADER START
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or https://opensource.org/licenses/CDDL-1.0.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
19 * CDDL HEADER END
22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
26 * Copyright (c) 2012 by Delphix. All rights reserved.
29 #ifndef _SYS_RR_RW_LOCK_H
30 #define _SYS_RR_RW_LOCK_H
34 #ifdef __cplusplus
35 extern "C" {
36 #endif
38 #include <sys/inttypes.h>
39 #include <sys/zfs_context.h>
40 #include <sys/zfs_refcount.h>
42 extern uint_t rrw_tsd_key;
45 * A reader-writer lock implementation that allows re-entrant reads, but
46 * still gives writers priority on "new" reads.
48 * See rrwlock.c for more details about the implementation.
50 * Fields of the rrwlock_t structure:
51 * - rr_lock: protects modification and reading of rrwlock_t fields
52 * - rr_cv: cv for waking up readers or waiting writers
53 * - rr_writer: thread id of the current writer
54 * - rr_anon_rount: number of active anonymous readers
55 * - rr_linked_rcount: total number of non-anonymous active readers
56 * - rr_writer_wanted: a writer wants the lock
58 typedef struct rrwlock {
59 kmutex_t rr_lock;
60 kcondvar_t rr_cv;
61 kthread_t *rr_writer;
62 zfs_refcount_t rr_anon_rcount;
63 zfs_refcount_t rr_linked_rcount;
64 boolean_t rr_writer_wanted;
65 boolean_t rr_track_all;
66 } rrwlock_t;
69 * 'tag' is used in reference counting tracking. The
70 * 'tag' must be the same in a rrw_enter() as in its
71 * corresponding rrw_exit().
73 void rrw_init(rrwlock_t *rrl, boolean_t track_all);
74 void rrw_destroy(rrwlock_t *rrl);
75 void rrw_enter(rrwlock_t *rrl, krw_t rw, const void *tag);
76 void rrw_enter_read(rrwlock_t *rrl, const void *tag);
77 void rrw_enter_read_prio(rrwlock_t *rrl, const void *tag);
78 void rrw_enter_write(rrwlock_t *rrl);
79 void rrw_exit(rrwlock_t *rrl, const void *tag);
80 boolean_t rrw_held(rrwlock_t *rrl, krw_t rw);
81 void rrw_tsd_destroy(void *arg);
83 #define RRW_READ_HELD(x) rrw_held(x, RW_READER)
84 #define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER)
85 #define RRW_LOCK_HELD(x) \
86 (rrw_held(x, RW_WRITER) || rrw_held(x, RW_READER))
89 * A reader-mostly lock implementation, tuning above reader-writer locks
90 * for hightly parallel read acquisitions, pessimizing write acquisitions.
92 * This should be a prime number. See comment in rrwlock.c near
93 * RRM_TD_LOCK() for details.
95 #define RRM_NUM_LOCKS 17
96 typedef struct rrmlock {
97 rrwlock_t locks[RRM_NUM_LOCKS];
98 } rrmlock_t;
100 void rrm_init(rrmlock_t *rrl, boolean_t track_all);
101 void rrm_destroy(rrmlock_t *rrl);
102 void rrm_enter(rrmlock_t *rrl, krw_t rw, const void *tag);
103 void rrm_enter_read(rrmlock_t *rrl, const void *tag);
104 void rrm_enter_write(rrmlock_t *rrl);
105 void rrm_exit(rrmlock_t *rrl, const void *tag);
106 boolean_t rrm_held(rrmlock_t *rrl, krw_t rw);
108 #define RRM_READ_HELD(x) rrm_held(x, RW_READER)
109 #define RRM_WRITE_HELD(x) rrm_held(x, RW_WRITER)
110 #define RRM_LOCK_HELD(x) \
111 (rrm_held(x, RW_WRITER) || rrm_held(x, RW_READER))
113 #ifdef __cplusplus
115 #endif
117 #endif /* _SYS_RR_RW_LOCK_H */