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
27struct 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	/* ref count on this data structure */
37	atomic_t refs;
38
39	/*
40	 * how many refs is this entry adding or deleting.  For
41	 * head refs, this may be a negative number because it is keeping
42	 * track of the total mods done to the reference count.
43	 * For individual refs, this will always be a positive number
44	 *
45	 * It may be more than one, since it is possible for a single
46	 * parent to have more than one ref on an extent
47	 */
48	int ref_mod;
49
50	unsigned int action:8;
51	unsigned int type:8;
52	/* is this node still in the rbtree? */
53	unsigned int is_head:1;
54	unsigned int in_tree:1;
55};
56
57struct btrfs_delayed_extent_op {
58	struct btrfs_disk_key key;
59	u64 flags_to_set;
60	unsigned int update_key:1;
61	unsigned int update_flags:1;
62	unsigned int is_data:1;
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 */
71struct btrfs_delayed_ref_head {
72	struct btrfs_delayed_ref_node node;
73
74	/*
75	 * the mutex is held while running the refs, and it is also
76	 * held when checking the sum of reference modifications.
77	 */
78	struct mutex mutex;
79
80	struct list_head cluster;
81
82	struct btrfs_delayed_extent_op *extent_op;
83	/*
84	 * when a new extent is allocated, it is just reserved in memory
85	 * The actual extent isn't inserted into the extent allocation tree
86	 * until the delayed ref is processed.  must_insert_reserved is
87	 * used to flag a delayed ref so the accounting can be updated
88	 * when a full insert is done.
89	 *
90	 * It is possible the extent will be freed before it is ever
91	 * inserted into the extent allocation tree.  In this case
92	 * we need to update the in ram accounting to properly reflect
93	 * the free has happened.
94	 */
95	unsigned int must_insert_reserved:1;
96	unsigned int is_data:1;
97};
98
99struct btrfs_delayed_tree_ref {
100	struct btrfs_delayed_ref_node node;
101	union {
102		u64 root;
103		u64 parent;
104	};
105	int level;
106};
107
108struct btrfs_delayed_data_ref {
109	struct btrfs_delayed_ref_node node;
110	union {
111		u64 root;
112		u64 parent;
113	};
114	u64 objectid;
115	u64 offset;
116};
117
118struct btrfs_delayed_ref_root {
119	struct rb_root root;
120
121	/* this spin lock protects the rbtree and the entries inside */
122	spinlock_t lock;
123
124	/* how many delayed ref updates we've queued, used by the
125	 * throttling code
126	 */
127	unsigned long num_entries;
128
129	/* total number of head nodes in tree */
130	unsigned long num_heads;
131
132	/* total number of head nodes ready for processing */
133	unsigned long num_heads_ready;
134
135	/*
136	 * set when the tree is flushing before a transaction commit,
137	 * used by the throttling code to decide if new updates need
138	 * to be run right away
139	 */
140	int flushing;
141
142	u64 run_delayed_start;
143};
144
145static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
146{
147	WARN_ON(atomic_read(&ref->refs) == 0);
148	if (atomic_dec_and_test(&ref->refs)) {
149		WARN_ON(ref->in_tree);
150		kfree(ref);
151	}
152}
153
154int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
155			       u64 bytenr, u64 num_bytes, u64 parent,
156			       u64 ref_root, int level, int action,
157			       struct btrfs_delayed_extent_op *extent_op);
158int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
159			       u64 bytenr, u64 num_bytes,
160			       u64 parent, u64 ref_root,
161			       u64 owner, u64 offset, int action,
162			       struct btrfs_delayed_extent_op *extent_op);
163int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
164				u64 bytenr, u64 num_bytes,
165				struct btrfs_delayed_extent_op *extent_op);
166
167struct btrfs_delayed_ref_head *
168btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
169int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr);
170int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
171			  u64 bytenr, u64 num_bytes, u64 orig_parent,
172			  u64 parent, u64 orig_ref_root, u64 ref_root,
173			  u64 orig_ref_generation, u64 ref_generation,
174			  u64 owner_objectid, int pin);
175int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
176			   struct btrfs_delayed_ref_head *head);
177int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
178			   struct list_head *cluster, u64 search_start);
179/*
180 * a node might live in a head or a regular ref, this lets you
181 * test for the proper type to use.
182 */
183static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
184{
185	return node->is_head;
186}
187
188/*
189 * helper functions to cast a node into its container
190 */
191static inline struct btrfs_delayed_tree_ref *
192btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
193{
194	WARN_ON(btrfs_delayed_ref_is_head(node));
195	return container_of(node, struct btrfs_delayed_tree_ref, node);
196}
197
198static inline struct btrfs_delayed_data_ref *
199btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
200{
201	WARN_ON(btrfs_delayed_ref_is_head(node));
202	return container_of(node, struct btrfs_delayed_data_ref, node);
203}
204
205static inline struct btrfs_delayed_ref_head *
206btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
207{
208	WARN_ON(!btrfs_delayed_ref_is_head(node));
209	return container_of(node, struct btrfs_delayed_ref_head, node);
210}
211#endif
212