2 * Copyright (C) 2008 Oracle. All rights reserved.
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.
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.
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.
18 #ifndef __DELAYED_REF__
19 #define __DELAYED_REF__
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 */
27 struct btrfs_delayed_ref_node {
28 struct rb_node rb_node;
30 /* the starting bytenr of the extent */
33 /* the size of the extent */
36 /* seq number to keep track of insertion order */
39 /* ref count on this data structure */
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
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
53 unsigned int action:8;
55 /* is this node still in the rbtree? */
56 unsigned int is_head:1;
57 unsigned int in_tree:1;
60 struct btrfs_delayed_extent_op {
61 struct btrfs_disk_key key;
64 unsigned int update_key:1;
65 unsigned int update_flags:1;
66 unsigned int is_data:1;
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.
75 struct btrfs_delayed_ref_head {
76 struct btrfs_delayed_ref_node node;
79 * the mutex is held while running the refs, and it is also
80 * held when checking the sum of reference modifications.
84 struct list_head cluster;
86 struct rb_node href_node;
88 struct btrfs_delayed_extent_op *extent_op;
90 * when a new extent is allocated, it is just reserved in memory
91 * The actual extent isn't inserted into the extent allocation tree
92 * until the delayed ref is processed. must_insert_reserved is
93 * used to flag a delayed ref so the accounting can be updated
94 * when a full insert is done.
96 * It is possible the extent will be freed before it is ever
97 * inserted into the extent allocation tree. In this case
98 * we need to update the in ram accounting to properly reflect
99 * the free has happened.
101 unsigned int must_insert_reserved:1;
102 unsigned int is_data:1;
105 struct btrfs_delayed_tree_ref {
106 struct btrfs_delayed_ref_node node;
112 struct btrfs_delayed_data_ref {
113 struct btrfs_delayed_ref_node node;
120 struct btrfs_delayed_ref_root {
123 /* head ref rbtree */
124 struct rb_root href_root;
126 /* this spin lock protects the rbtree and the entries inside */
129 /* how many delayed ref updates we've queued, used by the
132 unsigned long num_entries;
134 /* total number of head nodes in tree */
135 unsigned long num_heads;
137 /* total number of head nodes ready for processing */
138 unsigned long num_heads_ready;
141 * bumped when someone is making progress on the delayed
142 * refs, so that other procs know they are just adding to
143 * contention intead of helping
145 atomic_t procs_running_refs;
147 wait_queue_head_t wait;
150 * set when the tree is flushing before a transaction commit,
151 * used by the throttling code to decide if new updates need
152 * to be run right away
156 u64 run_delayed_start;
159 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
160 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
161 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
162 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
164 int btrfs_delayed_ref_init(void);
165 void btrfs_delayed_ref_exit(void);
167 static inline struct btrfs_delayed_extent_op *
168 btrfs_alloc_delayed_extent_op(void)
170 return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
174 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
177 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
180 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
182 WARN_ON(atomic_read(&ref->refs) == 0);
183 if (atomic_dec_and_test(&ref->refs)) {
184 WARN_ON(ref->in_tree);
186 case BTRFS_TREE_BLOCK_REF_KEY:
187 case BTRFS_SHARED_BLOCK_REF_KEY:
188 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
190 case BTRFS_EXTENT_DATA_REF_KEY:
191 case BTRFS_SHARED_DATA_REF_KEY:
192 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
195 kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
203 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
204 struct btrfs_trans_handle *trans,
205 u64 bytenr, u64 num_bytes, u64 parent,
206 u64 ref_root, int level, int action,
207 struct btrfs_delayed_extent_op *extent_op,
209 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
210 struct btrfs_trans_handle *trans,
211 u64 bytenr, u64 num_bytes,
212 u64 parent, u64 ref_root,
213 u64 owner, u64 offset, int action,
214 struct btrfs_delayed_extent_op *extent_op,
216 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
217 struct btrfs_trans_handle *trans,
218 u64 bytenr, u64 num_bytes,
219 struct btrfs_delayed_extent_op *extent_op);
220 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
221 struct btrfs_fs_info *fs_info,
222 struct btrfs_delayed_ref_root *delayed_refs,
223 struct btrfs_delayed_ref_head *head);
225 struct btrfs_delayed_ref_head *
226 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
227 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
228 struct btrfs_delayed_ref_head *head);
229 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
231 mutex_unlock(&head->mutex);
234 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
235 struct list_head *cluster, u64 search_start);
236 void btrfs_release_ref_cluster(struct list_head *cluster);
238 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
239 struct btrfs_delayed_ref_root *delayed_refs,
243 * delayed refs with a ref_seq > 0 must be held back during backref walking.
244 * this only applies to items in one of the fs-trees. for_cow items never need
245 * to be held back, so they won't get a ref_seq number.
247 static inline int need_ref_seq(int for_cow, u64 rootid)
252 if (rootid == BTRFS_FS_TREE_OBJECTID)
255 if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID)
262 * a node might live in a head or a regular ref, this lets you
263 * test for the proper type to use.
265 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
267 return node->is_head;
271 * helper functions to cast a node into its container
273 static inline struct btrfs_delayed_tree_ref *
274 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
276 WARN_ON(btrfs_delayed_ref_is_head(node));
277 return container_of(node, struct btrfs_delayed_tree_ref, node);
280 static inline struct btrfs_delayed_data_ref *
281 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
283 WARN_ON(btrfs_delayed_ref_is_head(node));
284 return container_of(node, struct btrfs_delayed_data_ref, node);
287 static inline struct btrfs_delayed_ref_head *
288 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
290 WARN_ON(!btrfs_delayed_ref_is_head(node));
291 return container_of(node, struct btrfs_delayed_ref_head, node);