| /* |
| * 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 http://www.opensolaris.org/os/licensing. |
| * 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. |
| */ |
| |
| #include <sys/zfs_context.h> |
| #include <sys/refcount.h> |
| |
| #ifdef _KERNEL |
| int reference_tracking_enable = FALSE; /* runs out of memory too easily */ |
| #else |
| int reference_tracking_enable = TRUE; |
| #endif |
| int reference_history = 3; /* tunable */ |
| |
| #ifdef ZFS_DEBUG |
| static kmem_cache_t *reference_cache; |
| static kmem_cache_t *reference_history_cache; |
| |
| void |
| zfs_refcount_init(void) |
| { |
| reference_cache = kmem_cache_create("reference_cache", |
| sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0); |
| |
| reference_history_cache = kmem_cache_create("reference_history_cache", |
| sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0); |
| } |
| |
| void |
| zfs_refcount_fini(void) |
| { |
| kmem_cache_destroy(reference_cache); |
| kmem_cache_destroy(reference_history_cache); |
| } |
| |
| void |
| zfs_refcount_create(zfs_refcount_t *rc) |
| { |
| mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL); |
| list_create(&rc->rc_list, sizeof (reference_t), |
| offsetof(reference_t, ref_link)); |
| list_create(&rc->rc_removed, sizeof (reference_t), |
| offsetof(reference_t, ref_link)); |
| rc->rc_count = 0; |
| rc->rc_removed_count = 0; |
| rc->rc_tracked = reference_tracking_enable; |
| } |
| |
| void |
| zfs_refcount_create_tracked(zfs_refcount_t *rc) |
| { |
| zfs_refcount_create(rc); |
| rc->rc_tracked = B_TRUE; |
| } |
| |
| void |
| zfs_refcount_create_untracked(zfs_refcount_t *rc) |
| { |
| zfs_refcount_create(rc); |
| rc->rc_tracked = B_FALSE; |
| } |
| |
| void |
| zfs_refcount_destroy_many(zfs_refcount_t *rc, uint64_t number) |
| { |
| reference_t *ref; |
| |
| ASSERT(rc->rc_count == number); |
| while ((ref = list_head(&rc->rc_list))) { |
| list_remove(&rc->rc_list, ref); |
| kmem_cache_free(reference_cache, ref); |
| } |
| list_destroy(&rc->rc_list); |
| |
| while ((ref = list_head(&rc->rc_removed))) { |
| list_remove(&rc->rc_removed, ref); |
| kmem_cache_free(reference_history_cache, ref->ref_removed); |
| kmem_cache_free(reference_cache, ref); |
| } |
| list_destroy(&rc->rc_removed); |
| mutex_destroy(&rc->rc_mtx); |
| } |
| |
| void |
| zfs_refcount_destroy(zfs_refcount_t *rc) |
| { |
| zfs_refcount_destroy_many(rc, 0); |
| } |
| |
| int |
| zfs_refcount_is_zero(zfs_refcount_t *rc) |
| { |
| return (rc->rc_count == 0); |
| } |
| |
| int64_t |
| zfs_refcount_count(zfs_refcount_t *rc) |
| { |
| return (rc->rc_count); |
| } |
| |
| int64_t |
| zfs_refcount_add_many(zfs_refcount_t *rc, uint64_t number, const void *holder) |
| { |
| reference_t *ref = NULL; |
| int64_t count; |
| |
| if (rc->rc_tracked) { |
| ref = kmem_cache_alloc(reference_cache, KM_SLEEP); |
| ref->ref_holder = holder; |
| ref->ref_number = number; |
| } |
| mutex_enter(&rc->rc_mtx); |
| ASSERT(rc->rc_count >= 0); |
| if (rc->rc_tracked) |
| list_insert_head(&rc->rc_list, ref); |
| rc->rc_count += number; |
| count = rc->rc_count; |
| mutex_exit(&rc->rc_mtx); |
| |
| return (count); |
| } |
| |
| int64_t |
| zfs_refcount_add(zfs_refcount_t *rc, const void *holder) |
| { |
| return (zfs_refcount_add_many(rc, 1, holder)); |
| } |
| |
| int64_t |
| zfs_refcount_remove_many(zfs_refcount_t *rc, uint64_t number, |
| const void *holder) |
| { |
| reference_t *ref; |
| int64_t count; |
| |
| mutex_enter(&rc->rc_mtx); |
| ASSERT(rc->rc_count >= number); |
| |
| if (!rc->rc_tracked) { |
| rc->rc_count -= number; |
| count = rc->rc_count; |
| mutex_exit(&rc->rc_mtx); |
| return (count); |
| } |
| |
| for (ref = list_head(&rc->rc_list); ref; |
| ref = list_next(&rc->rc_list, ref)) { |
| if (ref->ref_holder == holder && ref->ref_number == number) { |
| list_remove(&rc->rc_list, ref); |
| if (reference_history > 0) { |
| ref->ref_removed = |
| kmem_cache_alloc(reference_history_cache, |
| KM_SLEEP); |
| list_insert_head(&rc->rc_removed, ref); |
| rc->rc_removed_count++; |
| if (rc->rc_removed_count > reference_history) { |
| ref = list_tail(&rc->rc_removed); |
| list_remove(&rc->rc_removed, ref); |
| kmem_cache_free(reference_history_cache, |
| ref->ref_removed); |
| kmem_cache_free(reference_cache, ref); |
| rc->rc_removed_count--; |
| } |
| } else { |
| kmem_cache_free(reference_cache, ref); |
| } |
| rc->rc_count -= number; |
| count = rc->rc_count; |
| mutex_exit(&rc->rc_mtx); |
| return (count); |
| } |
| } |
| panic("No such hold %p on refcount %llx", holder, |
| (u_longlong_t)(uintptr_t)rc); |
| return (-1); |
| } |
| |
| int64_t |
| zfs_refcount_remove(zfs_refcount_t *rc, const void *holder) |
| { |
| return (zfs_refcount_remove_many(rc, 1, holder)); |
| } |
| |
| void |
| zfs_refcount_transfer(zfs_refcount_t *dst, zfs_refcount_t *src) |
| { |
| int64_t count, removed_count; |
| list_t list, removed; |
| |
| list_create(&list, sizeof (reference_t), |
| offsetof(reference_t, ref_link)); |
| list_create(&removed, sizeof (reference_t), |
| offsetof(reference_t, ref_link)); |
| |
| mutex_enter(&src->rc_mtx); |
| count = src->rc_count; |
| removed_count = src->rc_removed_count; |
| src->rc_count = 0; |
| src->rc_removed_count = 0; |
| list_move_tail(&list, &src->rc_list); |
| list_move_tail(&removed, &src->rc_removed); |
| mutex_exit(&src->rc_mtx); |
| |
| mutex_enter(&dst->rc_mtx); |
| dst->rc_count += count; |
| dst->rc_removed_count += removed_count; |
| list_move_tail(&dst->rc_list, &list); |
| list_move_tail(&dst->rc_removed, &removed); |
| mutex_exit(&dst->rc_mtx); |
| |
| list_destroy(&list); |
| list_destroy(&removed); |
| } |
| |
| void |
| zfs_refcount_transfer_ownership_many(zfs_refcount_t *rc, uint64_t number, |
| const void *current_holder, const void *new_holder) |
| { |
| reference_t *ref; |
| boolean_t found = B_FALSE; |
| |
| mutex_enter(&rc->rc_mtx); |
| if (!rc->rc_tracked) { |
| mutex_exit(&rc->rc_mtx); |
| return; |
| } |
| |
| for (ref = list_head(&rc->rc_list); ref; |
| ref = list_next(&rc->rc_list, ref)) { |
| if (ref->ref_holder == current_holder && |
| ref->ref_number == number) { |
| ref->ref_holder = new_holder; |
| found = B_TRUE; |
| break; |
| } |
| } |
| ASSERT(found); |
| mutex_exit(&rc->rc_mtx); |
| } |
| |
| void |
| zfs_refcount_transfer_ownership(zfs_refcount_t *rc, const void *current_holder, |
| const void *new_holder) |
| { |
| return (zfs_refcount_transfer_ownership_many(rc, 1, current_holder, |
| new_holder)); |
| } |
| |
| /* |
| * If tracking is enabled, return true if a reference exists that matches |
| * the "holder" tag. If tracking is disabled, then return true if a reference |
| * might be held. |
| */ |
| boolean_t |
| zfs_refcount_held(zfs_refcount_t *rc, const void *holder) |
| { |
| reference_t *ref; |
| |
| mutex_enter(&rc->rc_mtx); |
| |
| if (!rc->rc_tracked) { |
| mutex_exit(&rc->rc_mtx); |
| return (rc->rc_count > 0); |
| } |
| |
| for (ref = list_head(&rc->rc_list); ref; |
| ref = list_next(&rc->rc_list, ref)) { |
| if (ref->ref_holder == holder) { |
| mutex_exit(&rc->rc_mtx); |
| return (B_TRUE); |
| } |
| } |
| mutex_exit(&rc->rc_mtx); |
| return (B_FALSE); |
| } |
| |
| /* |
| * If tracking is enabled, return true if a reference does not exist that |
| * matches the "holder" tag. If tracking is disabled, always return true |
| * since the reference might not be held. |
| */ |
| boolean_t |
| zfs_refcount_not_held(zfs_refcount_t *rc, const void *holder) |
| { |
| reference_t *ref; |
| |
| mutex_enter(&rc->rc_mtx); |
| |
| if (!rc->rc_tracked) { |
| mutex_exit(&rc->rc_mtx); |
| return (B_TRUE); |
| } |
| |
| for (ref = list_head(&rc->rc_list); ref; |
| ref = list_next(&rc->rc_list, ref)) { |
| if (ref->ref_holder == holder) { |
| mutex_exit(&rc->rc_mtx); |
| return (B_FALSE); |
| } |
| } |
| mutex_exit(&rc->rc_mtx); |
| return (B_TRUE); |
| } |
| #endif /* ZFS_DEBUG */ |