xref: /openbmc/linux/fs/btrfs/delayed-ref.h (revision d7a3d85e)
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 	unsigned int no_quota:1;
56 	/* is this node still in the rbtree? */
57 	unsigned int is_head:1;
58 	unsigned int in_tree:1;
59 };
60 
61 struct btrfs_delayed_extent_op {
62 	struct btrfs_disk_key key;
63 	u64 flags_to_set;
64 	int level;
65 	unsigned int update_key:1;
66 	unsigned int update_flags:1;
67 	unsigned int is_data:1;
68 };
69 
70 /*
71  * the head refs are used to hold a lock on a given extent, which allows us
72  * to make sure that only one process is running the delayed refs
73  * at a time for a single extent.  They also store the sum of all the
74  * reference count modifications we've queued up.
75  */
76 struct btrfs_delayed_ref_head {
77 	struct btrfs_delayed_ref_node node;
78 
79 	/*
80 	 * the mutex is held while running the refs, and it is also
81 	 * held when checking the sum of reference modifications.
82 	 */
83 	struct mutex mutex;
84 
85 	spinlock_t lock;
86 	struct rb_root ref_root;
87 
88 	struct rb_node href_node;
89 
90 	struct btrfs_delayed_extent_op *extent_op;
91 
92 	/*
93 	 * This is used to track the final ref_mod from all the refs associated
94 	 * with this head ref, this is not adjusted as delayed refs are run,
95 	 * this is meant to track if we need to do the csum accounting or not.
96 	 */
97 	int total_ref_mod;
98 
99 	/*
100 	 * when a new extent is allocated, it is just reserved in memory
101 	 * The actual extent isn't inserted into the extent allocation tree
102 	 * until the delayed ref is processed.  must_insert_reserved is
103 	 * used to flag a delayed ref so the accounting can be updated
104 	 * when a full insert is done.
105 	 *
106 	 * It is possible the extent will be freed before it is ever
107 	 * inserted into the extent allocation tree.  In this case
108 	 * we need to update the in ram accounting to properly reflect
109 	 * the free has happened.
110 	 */
111 	unsigned int must_insert_reserved:1;
112 	unsigned int is_data:1;
113 	unsigned int processing:1;
114 };
115 
116 struct btrfs_delayed_tree_ref {
117 	struct btrfs_delayed_ref_node node;
118 	u64 root;
119 	u64 parent;
120 	int level;
121 };
122 
123 struct btrfs_delayed_data_ref {
124 	struct btrfs_delayed_ref_node node;
125 	u64 root;
126 	u64 parent;
127 	u64 objectid;
128 	u64 offset;
129 };
130 
131 struct btrfs_delayed_ref_root {
132 	/* head ref rbtree */
133 	struct rb_root href_root;
134 
135 	/* this spin lock protects the rbtree and the entries inside */
136 	spinlock_t lock;
137 
138 	/* how many delayed ref updates we've queued, used by the
139 	 * throttling code
140 	 */
141 	atomic_t num_entries;
142 
143 	/* total number of head nodes in tree */
144 	unsigned long num_heads;
145 
146 	/* total number of head nodes ready for processing */
147 	unsigned long num_heads_ready;
148 
149 	u64 pending_csums;
150 
151 	/*
152 	 * set when the tree is flushing before a transaction commit,
153 	 * used by the throttling code to decide if new updates need
154 	 * to be run right away
155 	 */
156 	int flushing;
157 
158 	u64 run_delayed_start;
159 };
160 
161 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
162 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
163 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
164 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
165 
166 int btrfs_delayed_ref_init(void);
167 void btrfs_delayed_ref_exit(void);
168 
169 static inline struct btrfs_delayed_extent_op *
170 btrfs_alloc_delayed_extent_op(void)
171 {
172 	return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
173 }
174 
175 static inline void
176 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
177 {
178 	if (op)
179 		kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
180 }
181 
182 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
183 {
184 	WARN_ON(atomic_read(&ref->refs) == 0);
185 	if (atomic_dec_and_test(&ref->refs)) {
186 		WARN_ON(ref->in_tree);
187 		switch (ref->type) {
188 		case BTRFS_TREE_BLOCK_REF_KEY:
189 		case BTRFS_SHARED_BLOCK_REF_KEY:
190 			kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
191 			break;
192 		case BTRFS_EXTENT_DATA_REF_KEY:
193 		case BTRFS_SHARED_DATA_REF_KEY:
194 			kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
195 			break;
196 		case 0:
197 			kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
198 			break;
199 		default:
200 			BUG();
201 		}
202 	}
203 }
204 
205 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
206 			       struct btrfs_trans_handle *trans,
207 			       u64 bytenr, u64 num_bytes, u64 parent,
208 			       u64 ref_root, int level, int action,
209 			       struct btrfs_delayed_extent_op *extent_op,
210 			       int no_quota);
211 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
212 			       struct btrfs_trans_handle *trans,
213 			       u64 bytenr, u64 num_bytes,
214 			       u64 parent, u64 ref_root,
215 			       u64 owner, u64 offset, int action,
216 			       struct btrfs_delayed_extent_op *extent_op,
217 			       int no_quota);
218 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
219 				struct btrfs_trans_handle *trans,
220 				u64 bytenr, u64 num_bytes,
221 				struct btrfs_delayed_extent_op *extent_op);
222 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
223 			      struct btrfs_fs_info *fs_info,
224 			      struct btrfs_delayed_ref_root *delayed_refs,
225 			      struct btrfs_delayed_ref_head *head);
226 
227 struct btrfs_delayed_ref_head *
228 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
229 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
230 			   struct btrfs_delayed_ref_head *head);
231 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
232 {
233 	mutex_unlock(&head->mutex);
234 }
235 
236 
237 struct btrfs_delayed_ref_head *
238 btrfs_select_ref_head(struct btrfs_trans_handle *trans);
239 
240 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
241 			    struct btrfs_delayed_ref_root *delayed_refs,
242 			    u64 seq);
243 
244 /*
245  * a node might live in a head or a regular ref, this lets you
246  * test for the proper type to use.
247  */
248 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
249 {
250 	return node->is_head;
251 }
252 
253 /*
254  * helper functions to cast a node into its container
255  */
256 static inline struct btrfs_delayed_tree_ref *
257 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
258 {
259 	WARN_ON(btrfs_delayed_ref_is_head(node));
260 	return container_of(node, struct btrfs_delayed_tree_ref, node);
261 }
262 
263 static inline struct btrfs_delayed_data_ref *
264 btrfs_delayed_node_to_data_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_data_ref, node);
268 }
269 
270 static inline struct btrfs_delayed_ref_head *
271 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
272 {
273 	WARN_ON(!btrfs_delayed_ref_is_head(node));
274 	return container_of(node, struct btrfs_delayed_ref_head, node);
275 }
276 #endif
277