FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/include/sys/zfs_refcount.h

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License (the "License").
      * You may not use this file except in compliance with the License.
      *
      * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      * or https://opensource.org/licenses/CDDL-1.0.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     */
    /*
     * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
     * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
     */
    
    #ifndef _SYS_ZFS_REFCOUNT_H
    #define _SYS_ZFS_REFCOUNT_H
    
    #include <sys/inttypes.h>
    #include <sys/list.h>
    #include <sys/zfs_context.h>
    
    #ifdef  __cplusplus
    extern "C" {
    #endif
    
    /*
     * If the reference is held only by the calling function and not any
     * particular object, use FTAG (which is a string) for the holder_tag.
     * Otherwise, use the object that holds the reference.
     */
    #define FTAG ((char *)(uintptr_t)__func__)
    
    #ifdef  ZFS_DEBUG
    typedef struct reference {
            list_node_t ref_link;
            const void *ref_holder;
            uint64_t ref_number;
            uint8_t *ref_removed;
    } reference_t;
    
    typedef struct refcount {
            kmutex_t rc_mtx;
            boolean_t rc_tracked;
            list_t rc_list;
            list_t rc_removed;
            uint64_t rc_count;
            uint64_t rc_removed_count;
    } zfs_refcount_t;
    
    /*
     * Note: zfs_refcount_t must be initialized with
     * refcount_create[_untracked]()
     */
    
    void zfs_refcount_create(zfs_refcount_t *);
    void zfs_refcount_create_untracked(zfs_refcount_t *);
    void zfs_refcount_create_tracked(zfs_refcount_t *);
    void zfs_refcount_destroy(zfs_refcount_t *);
    void zfs_refcount_destroy_many(zfs_refcount_t *, uint64_t);
    int zfs_refcount_is_zero(zfs_refcount_t *);
    int64_t zfs_refcount_count(zfs_refcount_t *);
    int64_t zfs_refcount_add(zfs_refcount_t *, const void *);
    int64_t zfs_refcount_remove(zfs_refcount_t *, const void *);
    /*
     * Note that (add|remove)_many add/remove one reference with "number" N,
     * _not_ make N references with "number" 1, which is what vanilla
     * zfs_refcount_(add|remove) would do if called N times.
     *
     * Attempting to remove a reference with number N when none exists is a
     * panic on debug kernels with reference_tracking enabled.
     */
    int64_t zfs_refcount_add_many(zfs_refcount_t *, uint64_t, const void *);
    int64_t zfs_refcount_remove_many(zfs_refcount_t *, uint64_t, const void *);
    void zfs_refcount_transfer(zfs_refcount_t *, zfs_refcount_t *);
    void zfs_refcount_transfer_ownership(zfs_refcount_t *, const void *,
        const void *);
    void zfs_refcount_transfer_ownership_many(zfs_refcount_t *, uint64_t,
        const void *, const void *);
    boolean_t zfs_refcount_held(zfs_refcount_t *, const void *);
    boolean_t zfs_refcount_not_held(zfs_refcount_t *, const void *);
    
    void zfs_refcount_init(void);
    void zfs_refcount_fini(void);
    
    #else   /* ZFS_DEBUG */
    
    typedef struct refcount {
            uint64_t rc_count;
   } zfs_refcount_t;
   
   #define zfs_refcount_create(rc) ((rc)->rc_count = 0)
   #define zfs_refcount_create_untracked(rc) ((rc)->rc_count = 0)
   #define zfs_refcount_create_tracked(rc) ((rc)->rc_count = 0)
   #define zfs_refcount_destroy(rc) ((rc)->rc_count = 0)
   #define zfs_refcount_destroy_many(rc, number) ((rc)->rc_count = 0)
   #define zfs_refcount_is_zero(rc) (zfs_refcount_count(rc) == 0)
   #define zfs_refcount_count(rc) atomic_load_64(&(rc)->rc_count)
   #define zfs_refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count)
   #define zfs_refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count)
   #define zfs_refcount_add_many(rc, number, holder) \
           atomic_add_64_nv(&(rc)->rc_count, number)
   #define zfs_refcount_remove_many(rc, number, holder) \
           atomic_add_64_nv(&(rc)->rc_count, -number)
   #define zfs_refcount_transfer(dst, src) { \
           uint64_t __tmp = zfs_refcount_count(src); \
           atomic_add_64(&(src)->rc_count, -__tmp); \
           atomic_add_64(&(dst)->rc_count, __tmp); \
   }
   #define zfs_refcount_transfer_ownership(rc, ch, nh)             ((void)0)
   #define zfs_refcount_transfer_ownership_many(rc, nr, ch, nh)    ((void)0)
   #define zfs_refcount_held(rc, holder)           (zfs_refcount_count(rc) > 0)
   #define zfs_refcount_not_held(rc, holder)               (B_TRUE)
   
   #define zfs_refcount_init()
   #define zfs_refcount_fini()
   
   #endif  /* ZFS_DEBUG */
   
   #ifdef  __cplusplus
   }
   #endif
   
   #endif /* _SYS_REFCOUNT_H */

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