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 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 unsigned int update_key:1; 64 unsigned int update_flags:1; 65 unsigned int is_data:1; 66 }; 67 68 /* 69 * the head refs are used to hold a lock on a given extent, which allows us 70 * to make sure that only one process is running the delayed refs 71 * at a time for a single extent. They also store the sum of all the 72 * reference count modifications we've queued up. 73 */ 74 struct btrfs_delayed_ref_head { 75 struct btrfs_delayed_ref_node node; 76 77 /* 78 * the mutex is held while running the refs, and it is also 79 * held when checking the sum of reference modifications. 80 */ 81 struct mutex mutex; 82 83 struct list_head cluster; 84 85 struct btrfs_delayed_extent_op *extent_op; 86 /* 87 * when a new extent is allocated, it is just reserved in memory 88 * The actual extent isn't inserted into the extent allocation tree 89 * until the delayed ref is processed. must_insert_reserved is 90 * used to flag a delayed ref so the accounting can be updated 91 * when a full insert is done. 92 * 93 * It is possible the extent will be freed before it is ever 94 * inserted into the extent allocation tree. In this case 95 * we need to update the in ram accounting to properly reflect 96 * the free has happened. 97 */ 98 unsigned int must_insert_reserved:1; 99 unsigned int is_data:1; 100 }; 101 102 struct btrfs_delayed_tree_ref { 103 struct btrfs_delayed_ref_node node; 104 u64 root; 105 u64 parent; 106 int level; 107 }; 108 109 struct btrfs_delayed_data_ref { 110 struct btrfs_delayed_ref_node node; 111 u64 root; 112 u64 parent; 113 u64 objectid; 114 u64 offset; 115 }; 116 117 struct btrfs_delayed_ref_root { 118 struct rb_root root; 119 120 /* this spin lock protects the rbtree and the entries inside */ 121 spinlock_t lock; 122 123 /* how many delayed ref updates we've queued, used by the 124 * throttling code 125 */ 126 unsigned long num_entries; 127 128 /* total number of head nodes in tree */ 129 unsigned long num_heads; 130 131 /* total number of head nodes ready for processing */ 132 unsigned long num_heads_ready; 133 134 /* 135 * set when the tree is flushing before a transaction commit, 136 * used by the throttling code to decide if new updates need 137 * to be run right away 138 */ 139 int flushing; 140 141 u64 run_delayed_start; 142 143 /* 144 * seq number of delayed refs. We need to know if a backref was being 145 * added before the currently processed ref or afterwards. 146 */ 147 u64 seq; 148 149 /* 150 * seq_list holds a list of all seq numbers that are currently being 151 * added to the list. While walking backrefs (btrfs_find_all_roots, 152 * qgroups), which might take some time, no newer ref must be processed, 153 * as it might influence the outcome of the walk. 154 */ 155 struct list_head seq_head; 156 157 /* 158 * when the only refs we have in the list must not be processed, we want 159 * to wait for more refs to show up or for the end of backref walking. 160 */ 161 wait_queue_head_t seq_wait; 162 }; 163 164 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) 165 { 166 WARN_ON(atomic_read(&ref->refs) == 0); 167 if (atomic_dec_and_test(&ref->refs)) { 168 WARN_ON(ref->in_tree); 169 kfree(ref); 170 } 171 } 172 173 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info, 174 struct btrfs_trans_handle *trans, 175 u64 bytenr, u64 num_bytes, u64 parent, 176 u64 ref_root, int level, int action, 177 struct btrfs_delayed_extent_op *extent_op, 178 int for_cow); 179 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info, 180 struct btrfs_trans_handle *trans, 181 u64 bytenr, u64 num_bytes, 182 u64 parent, u64 ref_root, 183 u64 owner, u64 offset, int action, 184 struct btrfs_delayed_extent_op *extent_op, 185 int for_cow); 186 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info, 187 struct btrfs_trans_handle *trans, 188 u64 bytenr, u64 num_bytes, 189 struct btrfs_delayed_extent_op *extent_op); 190 191 struct btrfs_delayed_ref_head * 192 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr); 193 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, 194 struct btrfs_delayed_ref_head *head); 195 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, 196 struct list_head *cluster, u64 search_start); 197 198 struct seq_list { 199 struct list_head list; 200 u64 seq; 201 }; 202 203 static inline u64 inc_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs) 204 { 205 assert_spin_locked(&delayed_refs->lock); 206 ++delayed_refs->seq; 207 return delayed_refs->seq; 208 } 209 210 static inline void 211 btrfs_get_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, 212 struct seq_list *elem) 213 { 214 assert_spin_locked(&delayed_refs->lock); 215 elem->seq = delayed_refs->seq; 216 list_add_tail(&elem->list, &delayed_refs->seq_head); 217 } 218 219 static inline void 220 btrfs_put_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, 221 struct seq_list *elem) 222 { 223 spin_lock(&delayed_refs->lock); 224 list_del(&elem->list); 225 wake_up(&delayed_refs->seq_wait); 226 spin_unlock(&delayed_refs->lock); 227 } 228 229 int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, 230 u64 seq); 231 232 /* 233 * delayed refs with a ref_seq > 0 must be held back during backref walking. 234 * this only applies to items in one of the fs-trees. for_cow items never need 235 * to be held back, so they won't get a ref_seq number. 236 */ 237 static inline int need_ref_seq(int for_cow, u64 rootid) 238 { 239 if (for_cow) 240 return 0; 241 242 if (rootid == BTRFS_FS_TREE_OBJECTID) 243 return 1; 244 245 if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID) 246 return 1; 247 248 return 0; 249 } 250 251 /* 252 * a node might live in a head or a regular ref, this lets you 253 * test for the proper type to use. 254 */ 255 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node) 256 { 257 return node->is_head; 258 } 259 260 /* 261 * helper functions to cast a node into its container 262 */ 263 static inline struct btrfs_delayed_tree_ref * 264 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node) 265 { 266 WARN_ON(btrfs_delayed_ref_is_head(node)); 267 return container_of(node, struct btrfs_delayed_tree_ref, node); 268 } 269 270 static inline struct btrfs_delayed_data_ref * 271 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node) 272 { 273 WARN_ON(btrfs_delayed_ref_is_head(node)); 274 return container_of(node, struct btrfs_delayed_data_ref, node); 275 } 276 277 static inline struct btrfs_delayed_ref_head * 278 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node) 279 { 280 WARN_ON(!btrfs_delayed_ref_is_head(node)); 281 return container_of(node, struct btrfs_delayed_ref_head, node); 282 } 283 #endif 284