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_node->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 size of the extent */ 34 u64 num_bytes; 35 36 /* seq number to keep track of insertion order */ 37 u64 seq; 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 unsigned int action:8; 54 unsigned int type:8; 55 /* is this node still in the rbtree? */ 56 unsigned int is_head:1; 57 unsigned int in_tree:1; 58 }; 59 60 struct btrfs_delayed_extent_op { 61 struct btrfs_disk_key key; 62 u64 flags_to_set; 63 int level; 64 unsigned int update_key:1; 65 unsigned int update_flags:1; 66 unsigned int is_data:1; 67 }; 68 69 /* 70 * the head refs are used to hold a lock on a given extent, which allows us 71 * to make sure that only one process is running the delayed refs 72 * at a time for a single extent. They also store the sum of all the 73 * reference count modifications we've queued up. 74 */ 75 struct btrfs_delayed_ref_head { 76 struct btrfs_delayed_ref_node node; 77 78 /* 79 * the mutex is held while running the refs, and it is also 80 * held when checking the sum of reference modifications. 81 */ 82 struct mutex mutex; 83 84 struct list_head cluster; 85 86 struct btrfs_delayed_extent_op *extent_op; 87 /* 88 * when a new extent is allocated, it is just reserved in memory 89 * The actual extent isn't inserted into the extent allocation tree 90 * until the delayed ref is processed. must_insert_reserved is 91 * used to flag a delayed ref so the accounting can be updated 92 * when a full insert is done. 93 * 94 * It is possible the extent will be freed before it is ever 95 * inserted into the extent allocation tree. In this case 96 * we need to update the in ram accounting to properly reflect 97 * the free has happened. 98 */ 99 unsigned int must_insert_reserved:1; 100 unsigned int is_data:1; 101 }; 102 103 struct btrfs_delayed_tree_ref { 104 struct btrfs_delayed_ref_node node; 105 u64 root; 106 u64 parent; 107 int level; 108 }; 109 110 struct btrfs_delayed_data_ref { 111 struct btrfs_delayed_ref_node node; 112 u64 root; 113 u64 parent; 114 u64 objectid; 115 u64 offset; 116 }; 117 118 struct btrfs_delayed_ref_root { 119 struct rb_root root; 120 121 /* this spin lock protects the rbtree and the entries inside */ 122 spinlock_t lock; 123 124 /* how many delayed ref updates we've queued, used by the 125 * throttling code 126 */ 127 unsigned long num_entries; 128 129 /* total number of head nodes in tree */ 130 unsigned long num_heads; 131 132 /* total number of head nodes ready for processing */ 133 unsigned long num_heads_ready; 134 135 /* 136 * bumped when someone is making progress on the delayed 137 * refs, so that other procs know they are just adding to 138 * contention intead of helping 139 */ 140 atomic_t procs_running_refs; 141 atomic_t ref_seq; 142 wait_queue_head_t wait; 143 144 /* 145 * set when the tree is flushing before a transaction commit, 146 * used by the throttling code to decide if new updates need 147 * to be run right away 148 */ 149 int flushing; 150 151 u64 run_delayed_start; 152 }; 153 154 extern struct kmem_cache *btrfs_delayed_ref_head_cachep; 155 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep; 156 extern struct kmem_cache *btrfs_delayed_data_ref_cachep; 157 extern struct kmem_cache *btrfs_delayed_extent_op_cachep; 158 159 int btrfs_delayed_ref_init(void); 160 void btrfs_delayed_ref_exit(void); 161 162 static inline struct btrfs_delayed_extent_op * 163 btrfs_alloc_delayed_extent_op(void) 164 { 165 return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS); 166 } 167 168 static inline void 169 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op) 170 { 171 if (op) 172 kmem_cache_free(btrfs_delayed_extent_op_cachep, op); 173 } 174 175 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) 176 { 177 WARN_ON(atomic_read(&ref->refs) == 0); 178 if (atomic_dec_and_test(&ref->refs)) { 179 WARN_ON(ref->in_tree); 180 switch (ref->type) { 181 case BTRFS_TREE_BLOCK_REF_KEY: 182 case BTRFS_SHARED_BLOCK_REF_KEY: 183 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref); 184 break; 185 case BTRFS_EXTENT_DATA_REF_KEY: 186 case BTRFS_SHARED_DATA_REF_KEY: 187 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref); 188 break; 189 case 0: 190 kmem_cache_free(btrfs_delayed_ref_head_cachep, ref); 191 break; 192 default: 193 BUG(); 194 } 195 } 196 } 197 198 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info, 199 struct btrfs_trans_handle *trans, 200 u64 bytenr, u64 num_bytes, u64 parent, 201 u64 ref_root, int level, int action, 202 struct btrfs_delayed_extent_op *extent_op, 203 int for_cow); 204 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info, 205 struct btrfs_trans_handle *trans, 206 u64 bytenr, u64 num_bytes, 207 u64 parent, u64 ref_root, 208 u64 owner, u64 offset, int action, 209 struct btrfs_delayed_extent_op *extent_op, 210 int for_cow); 211 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info, 212 struct btrfs_trans_handle *trans, 213 u64 bytenr, u64 num_bytes, 214 struct btrfs_delayed_extent_op *extent_op); 215 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans, 216 struct btrfs_fs_info *fs_info, 217 struct btrfs_delayed_ref_root *delayed_refs, 218 struct btrfs_delayed_ref_head *head); 219 220 struct btrfs_delayed_ref_head * 221 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr); 222 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, 223 struct btrfs_delayed_ref_head *head); 224 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head) 225 { 226 mutex_unlock(&head->mutex); 227 } 228 229 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, 230 struct list_head *cluster, u64 search_start); 231 void btrfs_release_ref_cluster(struct list_head *cluster); 232 233 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, 234 struct btrfs_delayed_ref_root *delayed_refs, 235 u64 seq); 236 237 /* 238 * delayed refs with a ref_seq > 0 must be held back during backref walking. 239 * this only applies to items in one of the fs-trees. for_cow items never need 240 * to be held back, so they won't get a ref_seq number. 241 */ 242 static inline int need_ref_seq(int for_cow, u64 rootid) 243 { 244 if (for_cow) 245 return 0; 246 247 if (rootid == BTRFS_FS_TREE_OBJECTID) 248 return 1; 249 250 if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID) 251 return 1; 252 253 return 0; 254 } 255 256 /* 257 * a node might live in a head or a regular ref, this lets you 258 * test for the proper type to use. 259 */ 260 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node) 261 { 262 return node->is_head; 263 } 264 265 /* 266 * helper functions to cast a node into its container 267 */ 268 static inline struct btrfs_delayed_tree_ref * 269 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node) 270 { 271 WARN_ON(btrfs_delayed_ref_is_head(node)); 272 return container_of(node, struct btrfs_delayed_tree_ref, node); 273 } 274 275 static inline struct btrfs_delayed_data_ref * 276 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node) 277 { 278 WARN_ON(btrfs_delayed_ref_is_head(node)); 279 return container_of(node, struct btrfs_delayed_data_ref, node); 280 } 281 282 static inline struct btrfs_delayed_ref_head * 283 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node) 284 { 285 WARN_ON(!btrfs_delayed_ref_is_head(node)); 286 return container_of(node, struct btrfs_delayed_ref_head, node); 287 } 288 #endif 289