GFS2: Fix bug in block allocation
[linux-2.6.git] / fs / btrfs / delayed-ref.h
blob3bec2ff0b15c907cee10209b46b1c07fdb8f6a03
1 /*
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->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 */
31 u64 bytenr;
33 /* the parent our backref will point to */
34 u64 parent;
36 /* the size of the extent */
37 u64 num_bytes;
39 /* ref count on this data structure */
40 atomic_t refs;
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
51 int ref_mod;
53 /* is this node still in the rbtree? */
54 unsigned int in_tree:1;
58 * the head refs are used to hold a lock on a given extent, which allows us
59 * to make sure that only one process is running the delayed refs
60 * at a time for a single extent. They also store the sum of all the
61 * reference count modifications we've queued up.
63 struct btrfs_delayed_ref_head {
64 struct btrfs_delayed_ref_node node;
67 * the mutex is held while running the refs, and it is also
68 * held when checking the sum of reference modifications.
70 struct mutex mutex;
72 struct list_head cluster;
75 * when a new extent is allocated, it is just reserved in memory
76 * The actual extent isn't inserted into the extent allocation tree
77 * until the delayed ref is processed. must_insert_reserved is
78 * used to flag a delayed ref so the accounting can be updated
79 * when a full insert is done.
81 * It is possible the extent will be freed before it is ever
82 * inserted into the extent allocation tree. In this case
83 * we need to update the in ram accounting to properly reflect
84 * the free has happened.
86 unsigned int must_insert_reserved:1;
89 struct btrfs_delayed_ref {
90 struct btrfs_delayed_ref_node node;
92 /* the root objectid our ref will point to */
93 u64 root;
95 /* the generation for the backref */
96 u64 generation;
98 /* owner_objectid of the backref */
99 u64 owner_objectid;
101 /* operation done by this entry in the rbtree */
102 u8 action;
104 /* if pin == 1, when the extent is freed it will be pinned until
105 * transaction commit
107 unsigned int pin:1;
110 struct btrfs_delayed_ref_root {
111 struct rb_root root;
113 /* this spin lock protects the rbtree and the entries inside */
114 spinlock_t lock;
116 /* how many delayed ref updates we've queued, used by the
117 * throttling code
119 unsigned long num_entries;
121 /* total number of head nodes in tree */
122 unsigned long num_heads;
124 /* total number of head nodes ready for processing */
125 unsigned long num_heads_ready;
128 * set when the tree is flushing before a transaction commit,
129 * used by the throttling code to decide if new updates need
130 * to be run right away
132 int flushing;
134 u64 run_delayed_start;
137 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
139 WARN_ON(atomic_read(&ref->refs) == 0);
140 if (atomic_dec_and_test(&ref->refs)) {
141 WARN_ON(ref->in_tree);
142 kfree(ref);
146 int btrfs_add_delayed_ref(struct btrfs_trans_handle *trans,
147 u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root,
148 u64 ref_generation, u64 owner_objectid, int action,
149 int pin);
151 struct btrfs_delayed_ref_head *
152 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
153 int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr);
154 int btrfs_lookup_extent_ref(struct btrfs_trans_handle *trans,
155 struct btrfs_root *root, u64 bytenr,
156 u64 num_bytes, u32 *refs);
157 int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
158 u64 bytenr, u64 num_bytes, u64 orig_parent,
159 u64 parent, u64 orig_ref_root, u64 ref_root,
160 u64 orig_ref_generation, u64 ref_generation,
161 u64 owner_objectid, int pin);
162 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
163 struct btrfs_delayed_ref_head *head);
164 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
165 struct list_head *cluster, u64 search_start);
167 * a node might live in a head or a regular ref, this lets you
168 * test for the proper type to use.
170 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
172 return node->parent == (u64)-1;
176 * helper functions to cast a node into its container
178 static inline struct btrfs_delayed_ref *
179 btrfs_delayed_node_to_ref(struct btrfs_delayed_ref_node *node)
181 WARN_ON(btrfs_delayed_ref_is_head(node));
182 return container_of(node, struct btrfs_delayed_ref, node);
186 static inline struct btrfs_delayed_ref_head *
187 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
189 WARN_ON(!btrfs_delayed_ref_is_head(node));
190 return container_of(node, struct btrfs_delayed_ref_head, node);
193 #endif