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/avl.h>
  31 #include <sys/list.h>
  32 #include <sys/zfs_context.h>
  33
  34 #ifdef  __cplusplus
  35 extern "C" {
  36 #endif
  37
  38 /*
  39  * If the reference is held only by the calling function and not any
  40  * particular object, use FTAG (which is a string) for the holder_tag.
  41  * Otherwise, use the object that holds the reference.
  42  */
  43 #define FTAG ((char *)(uintptr_t)__func__)
  44
  45 #ifdef  ZFS_DEBUG
  46 typedef struct reference {
  47         union {
  48                 avl_node_t a;
  49                 list_node_t l;
  50         } ref_link;
  51         const void *ref_holder;
  52         uint64_t ref_number;
  53         boolean_t ref_search;
  54 } reference_t;
  55
  56 typedef struct refcount {
  57         uint64_t rc_count;
  58         kmutex_t rc_mtx;
  59         avl_tree_t rc_tree;
  60         list_t rc_removed;
  61         uint_t rc_removed_count;
  62         boolean_t rc_tracked;
  63 } zfs_refcount_t;
  64
  65 /*
  66  * Note: zfs_refcount_t must be initialized with
  67  * refcount_create[_untracked]()
  68  */
  69
  70 void zfs_refcount_create(zfs_refcount_t *);
  71 void zfs_refcount_create_untracked(zfs_refcount_t *);
  72 void zfs_refcount_create_tracked(zfs_refcount_t *);
  73 void zfs_refcount_destroy(zfs_refcount_t *);
  74 void zfs_refcount_destroy_many(zfs_refcount_t *, uint64_t);
  75 int zfs_refcount_is_zero(zfs_refcount_t *);
  76 int64_t zfs_refcount_count(zfs_refcount_t *);
  77 int64_t zfs_refcount_add(zfs_refcount_t *, const void *);
  78 int64_t zfs_refcount_remove(zfs_refcount_t *, const void *);
  79 /*
  80  * Note that (add|remove)_many adds/removes one reference with "number" N,
  81  * _not_ N references with "number" 1, which is what (add|remove)_few does,
  82  * or what vanilla zfs_refcount_(add|remove) called N times would do.
  83  *
  84  * Attempting to remove a reference with number N when none exists is a
  85  * panic on debug kernels with reference_tracking enabled.
  86  */
  87 void zfs_refcount_add_few(zfs_refcount_t *, uint64_t, const void *);
  88 void zfs_refcount_remove_few(zfs_refcount_t *, uint64_t, const void *);
  89 int64_t zfs_refcount_add_many(zfs_refcount_t *, uint64_t, const void *);
  90 int64_t zfs_refcount_remove_many(zfs_refcount_t *, uint64_t, const void *);
  91 void zfs_refcount_transfer(zfs_refcount_t *, zfs_refcount_t *);
  92 void zfs_refcount_transfer_ownership(zfs_refcount_t *, const void *,
  93     const void *);
  94 void zfs_refcount_transfer_ownership_many(zfs_refcount_t *, uint64_t,
  95     const void *, const void *);
  96 boolean_t zfs_refcount_held(zfs_refcount_t *, const void *);
  97 boolean_t zfs_refcount_not_held(zfs_refcount_t *, const void *);
  98
  99 void zfs_refcount_init(void);
 100 void zfs_refcount_fini(void);
 101
 102 #else   /* ZFS_DEBUG */
 103
 104 typedef struct refcount {
 105         uint64_t rc_count;
 106 } zfs_refcount_t;
 107
 108 #define zfs_refcount_create(rc) ((rc)->rc_count = 0)
 109 #define zfs_refcount_create_untracked(rc) ((rc)->rc_count = 0)
 110 #define zfs_refcount_create_tracked(rc) ((rc)->rc_count = 0)
 111 #define zfs_refcount_destroy(rc) ((rc)->rc_count = 0)
 112 #define zfs_refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
 113 #define zfs_refcount_is_zero(rc) (zfs_refcount_count(rc) == 0)
 114 #define zfs_refcount_count(rc) atomic_load_64(&(rc)->rc_count)
 115 #define zfs_refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
 116 #define zfs_refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
 117 #define zfs_refcount_add_few(rc, number, holder) \
 118         atomic_add_64(&(rc)->rc_count, number)
 119 #define zfs_refcount_remove_few(rc, number, holder) \
 120         atomic_add_64(&(rc)->rc_count, -number)
 121 #define zfs_refcount_add_many(rc, number, holder) \
 122         atomic_add_64_nv(&(rc)->rc_count, number)
 123 #define zfs_refcount_remove_many(rc, number, holder) \
 124         atomic_add_64_nv(&(rc)->rc_count, -number)
 125 #define zfs_refcount_transfer(dst, src) { \
 126         uint64_t __tmp = zfs_refcount_count(src); \
 127         atomic_add_64(&(src)->rc_count, -__tmp); \
 128         atomic_add_64(&(dst)->rc_count, __tmp); \
 129 }
 130 #define zfs_refcount_transfer_ownership(rc, ch, nh)             ((void)0)
 131 #define zfs_refcount_transfer_ownership_many(rc, nr, ch, nh)    ((void)0)
 132 #define zfs_refcount_held(rc, holder)           (zfs_refcount_count(rc) > 0)
 133 #define zfs_refcount_not_held(rc, holder)               (B_TRUE)
 134
 135 #define zfs_refcount_init()
 136 #define zfs_refcount_fini()
 137
 138 #endif  /* ZFS_DEBUG */
 139
 140 #ifdef  __cplusplus
 141 }
 142 #endif
 143
 144 #endif /* _SYS_REFCOUNT_H */