include/sys/zfs_refcount.h

   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 https://opensource.org/licenses/CDDL-1.0.
  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_ZFS_REFCOUNT_H
  27 #define _SYS_ZFS_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         const 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 *, const void *);
  74 int64_t zfs_refcount_remove(zfs_refcount_t *, const void *);
  75 /*
  76  * Note that (add|remove)_many add/remove one reference with "number" N,
  77  * _not_ make N references with "number" 1, which is what vanilla
  78  * zfs_refcount_(add|remove) would do if called N times.
  79  *
  80  * Attempting to remove a reference with number N when none exists is a
  81  * panic on debug kernels with reference_tracking enabled.
  82  */
  83 int64_t zfs_refcount_add_many(zfs_refcount_t *, uint64_t, const void *);
  84 int64_t zfs_refcount_remove_many(zfs_refcount_t *, uint64_t, const void *);
  85 void zfs_refcount_transfer(zfs_refcount_t *, zfs_refcount_t *);
  86 void zfs_refcount_transfer_ownership(zfs_refcount_t *, const void *,
  87     const void *);
  88 void zfs_refcount_transfer_ownership_many(zfs_refcount_t *, uint64_t,
  89     const void *, const void *);
  90 boolean_t zfs_refcount_held(zfs_refcount_t *, const void *);
  91 boolean_t zfs_refcount_not_held(zfs_refcount_t *, const void *);
  92
  93 void zfs_refcount_init(void);
  94 void zfs_refcount_fini(void);
  95
  96 #else   /* ZFS_DEBUG */
  97
  98 typedef struct refcount {
  99         uint64_t rc_count;
 100 } zfs_refcount_t;
 101
 102 #define zfs_refcount_create(rc) ((rc)->rc_count = 0)
 103 #define zfs_refcount_create_untracked(rc) ((rc)->rc_count = 0)
 104 #define zfs_refcount_create_tracked(rc) ((rc)->rc_count = 0)
 105 #define zfs_refcount_destroy(rc) ((rc)->rc_count = 0)
 106 #define zfs_refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
 107 #define zfs_refcount_is_zero(rc) (zfs_refcount_count(rc) == 0)
 108 #define zfs_refcount_count(rc) atomic_load_64(&(rc)->rc_count)
 109 #define zfs_refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
 110 #define zfs_refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
 111 #define zfs_refcount_add_many(rc, number, holder) \
 112         atomic_add_64_nv(&(rc)->rc_count, number)
 113 #define zfs_refcount_remove_many(rc, number, holder) \
 114         atomic_add_64_nv(&(rc)->rc_count, -number)
 115 #define zfs_refcount_transfer(dst, src) { \
 116         uint64_t __tmp = zfs_refcount_count(src); \
 117         atomic_add_64(&(src)->rc_count, -__tmp); \
 118         atomic_add_64(&(dst)->rc_count, __tmp); \
 119 }
 120 #define zfs_refcount_transfer_ownership(rc, ch, nh)             ((void)0)
 121 #define zfs_refcount_transfer_ownership_many(rc, nr, ch, nh)    ((void)0)
 122 #define zfs_refcount_held(rc, holder)           (zfs_refcount_count(rc) > 0)
 123 #define zfs_refcount_not_held(rc, holder)               (B_TRUE)
 124
 125 #define zfs_refcount_init()
 126 #define zfs_refcount_fini()
 127
 128 #endif  /* ZFS_DEBUG */
 129
 130 #ifdef  __cplusplus
 131 }
 132 #endif
 133
 134 #endif /* _SYS_REFCOUNT_H */