Root/fs/btrfs/delayed-ref.h

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_lookup_extent_info(struct btrfs_trans_handle *trans,
171                 struct btrfs_root *root, u64 bytenr,
172                 u64 num_bytes, u64 *refs, u64 *flags);
173int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
174              u64 bytenr, u64 num_bytes, u64 orig_parent,
175              u64 parent, u64 orig_ref_root, u64 ref_root,
176              u64 orig_ref_generation, u64 ref_generation,
177              u64 owner_objectid, int pin);
178int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
179               struct btrfs_delayed_ref_head *head);
180int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
181               struct list_head *cluster, u64 search_start);
182/*
183 * a node might live in a head or a regular ref, this lets you
184 * test for the proper type to use.
185 */
186static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
187{
188    return node->is_head;
189}
190
191/*
192 * helper functions to cast a node into its container
193 */
194static inline struct btrfs_delayed_tree_ref *
195btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
196{
197    WARN_ON(btrfs_delayed_ref_is_head(node));
198    return container_of(node, struct btrfs_delayed_tree_ref, node);
199}
200
201static inline struct btrfs_delayed_data_ref *
202btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
203{
204    WARN_ON(btrfs_delayed_ref_is_head(node));
205    return container_of(node, struct btrfs_delayed_data_ref, node);
206}
207
208static inline struct btrfs_delayed_ref_head *
209btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
210{
211    WARN_ON(!btrfs_delayed_ref_is_head(node));
212    return container_of(node, struct btrfs_delayed_ref_head, node);
213}
214#endif
215

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