xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/refcount.h (revision 0f7643c7376dd69a08acbfc9d1d7d548b10c846a)
1 /*
2  * CDDL HEADER START
3  *
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.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
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]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
24  */
25 
26 #ifndef	_SYS_REFCOUNT_H
27 #define	_SYS_REFCOUNT_H
28 
29 #include <sys/inttypes.h>
30 #include <sys/list.h>
31 #include <sys/zfs_context.h>
32 
33 #ifdef	__cplusplus
34 extern "C" {
35 #endif
36 
37 /*
38  * If the reference is held only by the calling function and not any
39  * particular object, use FTAG (which is a string) for the holder_tag.
40  * Otherwise, use the object that holds the reference.
41  */
42 #define	FTAG ((char *)__func__)
43 
44 #ifdef	ZFS_DEBUG
45 typedef struct reference {
46 	list_node_t ref_link;
47 	void *ref_holder;
48 	uint64_t ref_number;
49 	uint8_t *ref_removed;
50 } reference_t;
51 
52 typedef struct refcount {
53 	kmutex_t rc_mtx;
54 	boolean_t rc_tracked;
55 	list_t rc_list;
56 	list_t rc_removed;
57 	uint64_t rc_count;
58 	uint64_t rc_removed_count;
59 } refcount_t;
60 
61 /* Note: refcount_t must be initialized with refcount_create[_untracked]() */
62 
63 void refcount_create(refcount_t *rc);
64 void refcount_create_untracked(refcount_t *rc);
65 void refcount_create_tracked(refcount_t *rc);
66 void refcount_destroy(refcount_t *rc);
67 void refcount_destroy_many(refcount_t *rc, uint64_t number);
68 int refcount_is_zero(refcount_t *rc);
69 int64_t refcount_count(refcount_t *rc);
70 int64_t refcount_add(refcount_t *rc, void *holder_tag);
71 int64_t refcount_remove(refcount_t *rc, void *holder_tag);
72 int64_t refcount_add_many(refcount_t *rc, uint64_t number, void *holder_tag);
73 int64_t refcount_remove_many(refcount_t *rc, uint64_t number, void *holder_tag);
74 void refcount_transfer(refcount_t *dst, refcount_t *src);
75 void refcount_transfer_ownership(refcount_t *, void *, void *);
76 boolean_t refcount_held(refcount_t *, void *);
77 boolean_t refcount_not_held(refcount_t *, void *);
78 
79 void refcount_init(void);
80 void refcount_fini(void);
81 
82 #else	/* ZFS_DEBUG */
83 
84 typedef struct refcount {
85 	uint64_t rc_count;
86 } refcount_t;
87 
88 #define	refcount_create(rc) ((rc)->rc_count = 0)
89 #define	refcount_create_untracked(rc) ((rc)->rc_count = 0)
90 #define	refcount_create_tracked(rc) ((rc)->rc_count = 0)
91 #define	refcount_destroy(rc) ((rc)->rc_count = 0)
92 #define	refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
93 #define	refcount_is_zero(rc) ((rc)->rc_count == 0)
94 #define	refcount_count(rc) ((rc)->rc_count)
95 #define	refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
96 #define	refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
97 #define	refcount_add_many(rc, number, holder) \
98 	atomic_add_64_nv(&(rc)->rc_count, number)
99 #define	refcount_remove_many(rc, number, holder) \
100 	atomic_add_64_nv(&(rc)->rc_count, -number)
101 #define	refcount_transfer(dst, src) { \
102 	uint64_t __tmp = (src)->rc_count; \
103 	atomic_add_64(&(src)->rc_count, -__tmp); \
104 	atomic_add_64(&(dst)->rc_count, __tmp); \
105 }
106 #define	refcount_transfer_ownership(rc, current_holder, new_holder)
107 #define	refcount_held(rc, holder)		((rc)->rc_count > 0)
108 #define	refcount_not_held(rc, holder)		(B_TRUE)
109 
110 #define	refcount_init()
111 #define	refcount_fini()
112 
113 #endif	/* ZFS_DEBUG */
114 
115 #ifdef	__cplusplus
116 }
117 #endif
118 
119 #endif /* _SYS_REFCOUNT_H */
120