xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/refcount.h (revision e914ace2e9d9bf2dbf9a1f1ce81cb776022096f5)
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 *)(uintptr_t)__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 } zfs_refcount_t;
60 
61 /*
62  * Note: zfs_refcount_t must be initialized with
63  * refcount_create[_untracked]()
64  */
65 
66 void zfs_refcount_create(zfs_refcount_t *);
67 void zfs_refcount_create_untracked(zfs_refcount_t *);
68 void zfs_refcount_create_tracked(zfs_refcount_t *);
69 void zfs_refcount_destroy(zfs_refcount_t *);
70 void zfs_refcount_destroy_many(zfs_refcount_t *, uint64_t);
71 int zfs_refcount_is_zero(zfs_refcount_t *);
72 int64_t zfs_refcount_count(zfs_refcount_t *);
73 int64_t zfs_refcount_add(zfs_refcount_t *, void *);
74 int64_t zfs_refcount_remove(zfs_refcount_t *, void *);
75 int64_t zfs_refcount_add_many(zfs_refcount_t *, uint64_t, void *);
76 int64_t zfs_refcount_remove_many(zfs_refcount_t *, uint64_t, void *);
77 void zfs_refcount_transfer(zfs_refcount_t *, zfs_refcount_t *);
78 void zfs_refcount_transfer_ownership(zfs_refcount_t *, void *, void *);
79 boolean_t zfs_refcount_held(zfs_refcount_t *, void *);
80 boolean_t zfs_refcount_not_held(zfs_refcount_t *, void *);
81 
82 void zfs_refcount_init(void);
83 void zfs_refcount_fini(void);
84 
85 #else	/* ZFS_DEBUG */
86 
87 typedef struct refcount {
88 	uint64_t rc_count;
89 } zfs_refcount_t;
90 
91 #define	zfs_refcount_create(rc) ((rc)->rc_count = 0)
92 #define	zfs_refcount_create_untracked(rc) ((rc)->rc_count = 0)
93 #define	zfs_refcount_create_tracked(rc) ((rc)->rc_count = 0)
94 #define	zfs_refcount_destroy(rc) ((rc)->rc_count = 0)
95 #define	zfs_refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
96 #define	zfs_refcount_is_zero(rc) ((rc)->rc_count == 0)
97 #define	zfs_refcount_count(rc) ((rc)->rc_count)
98 #define	zfs_refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
99 #define	zfs_refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
100 #define	zfs_refcount_add_many(rc, number, holder) \
101 	atomic_add_64_nv(&(rc)->rc_count, number)
102 #define	zfs_refcount_remove_many(rc, number, holder) \
103 	atomic_add_64_nv(&(rc)->rc_count, -number)
104 #define	zfs_refcount_transfer(dst, src) { \
105 	uint64_t __tmp = (src)->rc_count; \
106 	atomic_add_64(&(src)->rc_count, -__tmp); \
107 	atomic_add_64(&(dst)->rc_count, __tmp); \
108 }
109 #define	zfs_refcount_transfer_ownership(rc, current_holder, new_holder)	(void)0
110 #define	zfs_refcount_held(rc, holder)		((rc)->rc_count > 0)
111 #define	zfs_refcount_not_held(rc, holder)		(B_TRUE)
112 
113 #define	zfs_refcount_init()
114 #define	zfs_refcount_fini()
115 
116 #endif	/* ZFS_DEBUG */
117 
118 #ifdef	__cplusplus
119 }
120 #endif
121 
122 #endif /* _SYS_REFCOUNT_H */
123