1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (C) 2008 Oracle. All rights reserved.
4 */
5
6 #ifndef BTRFS_DELAYED_REF_H
7 #define BTRFS_DELAYED_REF_H
8
9 #include <linux/refcount.h>
10
11 /* these are the possible values of struct btrfs_delayed_ref_node->action */
12 #define BTRFS_ADD_DELAYED_REF 1 /* add one backref to the tree */
13 #define BTRFS_DROP_DELAYED_REF 2 /* delete one backref from the tree */
14 #define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
15 #define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
16
17 struct btrfs_delayed_ref_node {
18 struct rb_node ref_node;
19 /*
20 * If action is BTRFS_ADD_DELAYED_REF, also link this node to
21 * ref_head->ref_add_list, then we do not need to iterate the
22 * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
23 */
24 struct list_head add_list;
25
26 /* the starting bytenr of the extent */
27 u64 bytenr;
28
29 /* the size of the extent */
30 u64 num_bytes;
31
32 /* seq number to keep track of insertion order */
33 u64 seq;
34
35 /* ref count on this data structure */
36 refcount_t refs;
37
38 /*
39 * how many refs is this entry adding or deleting. For
40 * head refs, this may be a negative number because it is keeping
41 * track of the total mods done to the reference count.
42 * For individual refs, this will always be a positive number
43 *
44 * It may be more than one, since it is possible for a single
45 * parent to have more than one ref on an extent
46 */
47 int ref_mod;
48
49 unsigned int action:8;
50 unsigned int type:8;
51 /* is this node still in the rbtree? */
52 unsigned int is_head:1;
53 unsigned int in_tree:1;
54 };
55
56 struct btrfs_delayed_extent_op {
57 struct btrfs_disk_key key;
58 u8 level;
59 bool update_key;
60 bool update_flags;
61 bool is_data;
62 u64 flags_to_set;
63 };
64
65 /*
66 * the head refs are used to hold a lock on a given extent, which allows us
67 * to make sure that only one process is running the delayed refs
68 * at a time for a single extent. They also store the sum of all the
69 * reference count modifications we've queued up.
70 */
71 struct btrfs_delayed_ref_head {
72 u64 bytenr;
73 u64 num_bytes;
74 refcount_t refs;
75 /*
76 * the mutex is held while running the refs, and it is also
77 * held when checking the sum of reference modifications.
78 */
79 struct mutex mutex;
80
81 spinlock_t lock;
82 struct rb_root ref_tree;
83 /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
84 struct list_head ref_add_list;
85
86 struct rb_node href_node;
87
88 struct btrfs_delayed_extent_op *extent_op;
89
90 /*
91 * This is used to track the final ref_mod from all the refs associated
92 * with this head ref, this is not adjusted as delayed refs are run,
93 * this is meant to track if we need to do the csum accounting or not.
94 */
95 int total_ref_mod;
96
97 /*
98 * This is the current outstanding mod references for this bytenr. This
99 * is used with lookup_extent_info to get an accurate reference count
100 * for a bytenr, so it is adjusted as delayed refs are run so that any
101 * on disk reference count + ref_mod is accurate.
102 */
103 int ref_mod;
104
105 /*
106 * For qgroup reserved space freeing.
107 *
108 * ref_root and reserved will be recorded after
109 * BTRFS_ADD_DELAYED_EXTENT is called.
110 * And will be used to free reserved qgroup space at
111 * run_delayed_refs() time.
112 */
113 u64 qgroup_ref_root;
114 u64 qgroup_reserved;
115
116 /*
117 * when a new extent is allocated, it is just reserved in memory
118 * The actual extent isn't inserted into the extent allocation tree
119 * until the delayed ref is processed. must_insert_reserved is
120 * used to flag a delayed ref so the accounting can be updated
121 * when a full insert is done.
122 *
123 * It is possible the extent will be freed before it is ever
124 * inserted into the extent allocation tree. In this case
125 * we need to update the in ram accounting to properly reflect
126 * the free has happened.
127 */
128 unsigned int must_insert_reserved:1;
129 unsigned int is_data:1;
130 unsigned int is_system:1;
131 unsigned int processing:1;
132 };
133
134 struct btrfs_delayed_tree_ref {
135 struct btrfs_delayed_ref_node node;
136 u64 root;
137 u64 parent;
138 int level;
139 };
140
141 struct btrfs_delayed_data_ref {
142 struct btrfs_delayed_ref_node node;
143 u64 root;
144 u64 parent;
145 u64 objectid;
146 u64 offset;
147 };
148
149 struct btrfs_delayed_ref_root {
150 /* head ref rbtree */
151 struct rb_root href_root;
152
153 /* dirty extent records */
154 struct rb_root dirty_extent_root;
155
156 /* this spin lock protects the rbtree and the entries inside */
157 spinlock_t lock;
158
159 /* how many delayed ref updates we've queued, used by the
160 * throttling code
161 */
162 atomic_t num_entries;
163
164 /* total number of head nodes in tree */
165 unsigned long num_heads;
166
167 /* total number of head nodes ready for processing */
168 unsigned long num_heads_ready;
169
170 u64 pending_csums;
171
172 /*
173 * set when the tree is flushing before a transaction commit,
174 * used by the throttling code to decide if new updates need
175 * to be run right away
176 */
177 int flushing;
178
179 u64 run_delayed_start;
180
181 /*
182 * To make qgroup to skip given root.
183 * This is for snapshot, as btrfs_qgroup_inherit() will manually
184 * modify counters for snapshot and its source, so we should skip
185 * the snapshot in new_root/old_roots or it will get calculated twice
186 */
187 u64 qgroup_to_skip;
188 };
189
190 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
191 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
192 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
193 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
194
195 int __init btrfs_delayed_ref_init(void);
196 void __cold btrfs_delayed_ref_exit(void);
197
198 static inline struct btrfs_delayed_extent_op *
btrfs_alloc_delayed_extent_op(void)199 btrfs_alloc_delayed_extent_op(void)
200 {
201 return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
202 }
203
204 static inline void
btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op * op)205 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
206 {
207 if (op)
208 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
209 }
210
btrfs_put_delayed_ref(struct btrfs_delayed_ref_node * ref)211 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
212 {
213 WARN_ON(refcount_read(&ref->refs) == 0);
214 if (refcount_dec_and_test(&ref->refs)) {
215 WARN_ON(ref->in_tree);
216 switch (ref->type) {
217 case BTRFS_TREE_BLOCK_REF_KEY:
218 case BTRFS_SHARED_BLOCK_REF_KEY:
219 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
220 break;
221 case BTRFS_EXTENT_DATA_REF_KEY:
222 case BTRFS_SHARED_DATA_REF_KEY:
223 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
224 break;
225 default:
226 BUG();
227 }
228 }
229 }
230
btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head * head)231 static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
232 {
233 if (refcount_dec_and_test(&head->refs))
234 kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
235 }
236
237 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
238 u64 bytenr, u64 num_bytes, u64 parent,
239 u64 ref_root, int level, int action,
240 struct btrfs_delayed_extent_op *extent_op,
241 int *old_ref_mod, int *new_ref_mod);
242 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
243 u64 bytenr, u64 num_bytes,
244 u64 parent, u64 ref_root,
245 u64 owner, u64 offset, u64 reserved, int action,
246 int *old_ref_mod, int *new_ref_mod);
247 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
248 struct btrfs_trans_handle *trans,
249 u64 bytenr, u64 num_bytes,
250 struct btrfs_delayed_extent_op *extent_op);
251 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
252 struct btrfs_delayed_ref_root *delayed_refs,
253 struct btrfs_delayed_ref_head *head);
254
255 struct btrfs_delayed_ref_head *
256 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
257 u64 bytenr);
258 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
259 struct btrfs_delayed_ref_head *head);
btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head * head)260 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
261 {
262 mutex_unlock(&head->mutex);
263 }
264
265
266 struct btrfs_delayed_ref_head *
267 btrfs_select_ref_head(struct btrfs_trans_handle *trans);
268
269 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
270
271 /*
272 * helper functions to cast a node into its container
273 */
274 static inline struct btrfs_delayed_tree_ref *
btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node * node)275 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
276 {
277 return container_of(node, struct btrfs_delayed_tree_ref, node);
278 }
279
280 static inline struct btrfs_delayed_data_ref *
btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node * node)281 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
282 {
283 return container_of(node, struct btrfs_delayed_data_ref, node);
284 }
285
286 #endif
287