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