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
btrfs_put_delayed_ref(struct btrfs_delayed_ref_node * ref)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
inc_delayed_seq(struct btrfs_delayed_ref_root * delayed_refs)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
btrfs_get_delayed_seq(struct btrfs_delayed_ref_root * delayed_refs,struct seq_list * elem)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
btrfs_put_delayed_seq(struct btrfs_delayed_ref_root * delayed_refs,struct seq_list * elem)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 */
need_ref_seq(int for_cow,u64 rootid)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 */
btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node * node)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 *
btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node * node)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 *
btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node * node)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 *
btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node * node)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