1 /* 2 * Copyright (C) 2008 Oracle. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 #ifndef __DELAYED_REF__ 19 #define __DELAYED_REF__ 20 21 /* these are the possible values of struct btrfs_delayed_ref->action */ 22 #define BTRFS_ADD_DELAYED_REF 1 /* add one backref to the tree */ 23 #define BTRFS_DROP_DELAYED_REF 2 /* delete one backref from the tree */ 24 #define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */ 25 #define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */ 26 27 struct btrfs_delayed_ref_node { 28 struct rb_node rb_node; 29 30 /* the starting bytenr of the extent */ 31 u64 bytenr; 32 33 /* the parent our backref will point to */ 34 u64 parent; 35 36 /* the size of the extent */ 37 u64 num_bytes; 38 39 /* ref count on this data structure */ 40 atomic_t refs; 41 42 /* 43 * how many refs is this entry adding or deleting. For 44 * head refs, this may be a negative number because it is keeping 45 * track of the total mods done to the reference count. 46 * For individual refs, this will always be a positive number 47 * 48 * It may be more than one, since it is possible for a single 49 * parent to have more than one ref on an extent 50 */ 51 int ref_mod; 52 53 /* is this node still in the rbtree? */ 54 unsigned int in_tree:1; 55 }; 56 57 /* 58 * the head refs are used to hold a lock on a given extent, which allows us 59 * to make sure that only one process is running the delayed refs 60 * at a time for a single extent. They also store the sum of all the 61 * reference count modifications we've queued up. 62 */ 63 struct btrfs_delayed_ref_head { 64 struct btrfs_delayed_ref_node node; 65 66 /* 67 * the mutex is held while running the refs, and it is also 68 * held when checking the sum of reference modifications. 69 */ 70 struct mutex mutex; 71 72 struct list_head cluster; 73 74 /* 75 * when a new extent is allocated, it is just reserved in memory 76 * The actual extent isn't inserted into the extent allocation tree 77 * until the delayed ref is processed. must_insert_reserved is 78 * used to flag a delayed ref so the accounting can be updated 79 * when a full insert is done. 80 * 81 * It is possible the extent will be freed before it is ever 82 * inserted into the extent allocation tree. In this case 83 * we need to update the in ram accounting to properly reflect 84 * the free has happened. 85 */ 86 unsigned int must_insert_reserved:1; 87 }; 88 89 struct btrfs_delayed_ref { 90 struct btrfs_delayed_ref_node node; 91 92 /* the root objectid our ref will point to */ 93 u64 root; 94 95 /* the generation for the backref */ 96 u64 generation; 97 98 /* owner_objectid of the backref */ 99 u64 owner_objectid; 100 101 /* operation done by this entry in the rbtree */ 102 u8 action; 103 104 /* if pin == 1, when the extent is freed it will be pinned until 105 * transaction commit 106 */ 107 unsigned int pin:1; 108 }; 109 110 struct btrfs_delayed_ref_root { 111 struct rb_root root; 112 113 /* this spin lock protects the rbtree and the entries inside */ 114 spinlock_t lock; 115 116 /* how many delayed ref updates we've queued, used by the 117 * throttling code 118 */ 119 unsigned long num_entries; 120 121 /* total number of head nodes in tree */ 122 unsigned long num_heads; 123 124 /* total number of head nodes ready for processing */ 125 unsigned long num_heads_ready; 126 127 /* 128 * set when the tree is flushing before a transaction commit, 129 * used by the throttling code to decide if new updates need 130 * to be run right away 131 */ 132 int flushing; 133 134 u64 run_delayed_start; 135 }; 136 137 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) 138 { 139 WARN_ON(atomic_read(&ref->refs) == 0); 140 if (atomic_dec_and_test(&ref->refs)) { 141 WARN_ON(ref->in_tree); 142 kfree(ref); 143 } 144 } 145 146 int btrfs_add_delayed_ref(struct btrfs_trans_handle *trans, 147 u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root, 148 u64 ref_generation, u64 owner_objectid, int action, 149 int pin); 150 151 struct btrfs_delayed_ref_head * 152 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr); 153 int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr); 154 int btrfs_lookup_extent_ref(struct btrfs_trans_handle *trans, 155 struct btrfs_root *root, u64 bytenr, 156 u64 num_bytes, u32 *refs); 157 int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans, 158 u64 bytenr, u64 num_bytes, u64 orig_parent, 159 u64 parent, u64 orig_ref_root, u64 ref_root, 160 u64 orig_ref_generation, u64 ref_generation, 161 u64 owner_objectid, int pin); 162 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, 163 struct btrfs_delayed_ref_head *head); 164 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, 165 struct list_head *cluster, u64 search_start); 166 /* 167 * a node might live in a head or a regular ref, this lets you 168 * test for the proper type to use. 169 */ 170 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node) 171 { 172 return node->parent == (u64)-1; 173 } 174 175 /* 176 * helper functions to cast a node into its container 177 */ 178 static inline struct btrfs_delayed_ref * 179 btrfs_delayed_node_to_ref(struct btrfs_delayed_ref_node *node) 180 { 181 WARN_ON(btrfs_delayed_ref_is_head(node)); 182 return container_of(node, struct btrfs_delayed_ref, node); 183 184 } 185 186 static inline struct btrfs_delayed_ref_head * 187 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node) 188 { 189 WARN_ON(!btrfs_delayed_ref_is_head(node)); 190 return container_of(node, struct btrfs_delayed_ref_head, node); 191 192 } 193 #endif 194