1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _BCACHEFS_DISK_ACCOUNTING_FORMAT_H
3 #define _BCACHEFS_DISK_ACCOUNTING_FORMAT_H
4
5 #include "replicas_format.h"
6
7 /*
8 * Disk accounting - KEY_TYPE_accounting - on disk format:
9 *
10 * Here, the key has considerably more structure than a typical key (bpos); an
11 * accounting key is 'struct disk_accounting_pos', which is a union of bpos.
12 *
13 * More specifically: a key is just a muliword integer (where word endianness
14 * matches native byte order), so we're treating bpos as an opaque 20 byte
15 * integer and mapping bch_accounting_key to that.
16 *
17 * This is a type-tagged union of all our various subtypes; a disk accounting
18 * key can be device counters, replicas counters, et cetera - it's extensible.
19 *
20 * The value is a list of u64s or s64s; the number of counters is specific to a
21 * given accounting type.
22 *
23 * Unlike with other key types, updates are _deltas_, and the deltas are not
24 * resolved until the update to the underlying btree, done by btree write buffer
25 * flush or journal replay.
26 *
27 * Journal replay in particular requires special handling. The journal tracks a
28 * range of entries which may possibly have not yet been applied to the btree
29 * yet - it does not know definitively whether individual entries are dirty and
30 * still need to be applied.
31 *
32 * To handle this, we use the version field of struct bkey, and give every
33 * accounting update a unique version number - a total ordering in time; the
34 * version number is derived from the key's position in the journal. Then
35 * journal replay can compare the version number of the key from the journal
36 * with the version number of the key in the btree to determine if a key needs
37 * to be replayed.
38 *
39 * For this to work, we must maintain this strict time ordering of updates as
40 * they are flushed to the btree, both via write buffer flush and via journal
41 * replay. This has complications for the write buffer code while journal replay
42 * is still in progress; the write buffer cannot flush any accounting keys to
43 * the btree until journal replay has finished replaying its accounting keys, or
44 * the (newer) version number of the keys from the write buffer will cause
45 * updates from journal replay to be lost.
46 */
47
48 struct bch_accounting {
49 struct bch_val v;
50 __u64 d[];
51 };
52
53 #define BCH_ACCOUNTING_MAX_COUNTERS 3
54
55 #define BCH_DATA_TYPES() \
56 x(free, 0) \
57 x(sb, 1) \
58 x(journal, 2) \
59 x(btree, 3) \
60 x(user, 4) \
61 x(cached, 5) \
62 x(parity, 6) \
63 x(stripe, 7) \
64 x(need_gc_gens, 8) \
65 x(need_discard, 9) \
66 x(unstriped, 10)
67
68 enum bch_data_type {
69 #define x(t, n) BCH_DATA_##t,
70 BCH_DATA_TYPES()
71 #undef x
72 BCH_DATA_NR
73 };
74
75 static inline bool data_type_is_empty(enum bch_data_type type)
76 {
77 switch (type) {
78 case BCH_DATA_free:
79 case BCH_DATA_need_gc_gens:
80 case BCH_DATA_need_discard:
81 return true;
82 default:
83 return false;
84 }
85 }
86
87 static inline bool data_type_is_hidden(enum bch_data_type type)
88 {
89 switch (type) {
90 case BCH_DATA_sb:
91 case BCH_DATA_journal:
92 return true;
93 default:
94 return false;
95 }
96 }
97
98 #define BCH_DISK_ACCOUNTING_TYPES() \
99 x(nr_inodes, 0) \
100 x(persistent_reserved, 1) \
101 x(replicas, 2) \
102 x(dev_data_type, 3) \
103 x(compression, 4) \
104 x(snapshot, 5) \
105 x(btree, 6) \
106 x(rebalance_work, 7) \
107 x(inum, 8)
108
109 enum disk_accounting_type {
110 #define x(f, nr) BCH_DISK_ACCOUNTING_##f = nr,
111 BCH_DISK_ACCOUNTING_TYPES()
112 #undef x
113 BCH_DISK_ACCOUNTING_TYPE_NR,
114 };
115
116 struct bch_nr_inodes {
117 };
118
119 struct bch_persistent_reserved {
120 __u8 nr_replicas;
121 };
122
123 struct bch_dev_data_type {
124 __u8 dev;
125 __u8 data_type;
126 };
127
128 struct bch_acct_compression {
129 __u8 type;
130 };
131
132 struct bch_acct_snapshot {
133 __u32 id;
134 } __packed;
135
136 struct bch_acct_btree {
137 __u32 id;
138 } __packed;
139
140 struct bch_acct_inum {
141 __u64 inum;
142 } __packed;
143
144 struct bch_acct_rebalance_work {
145 };
146
147 struct disk_accounting_pos {
148 union {
149 struct {
150 __u8 type;
151 union {
152 struct bch_nr_inodes nr_inodes;
153 struct bch_persistent_reserved persistent_reserved;
154 struct bch_replicas_entry_v1 replicas;
155 struct bch_dev_data_type dev_data_type;
156 struct bch_acct_compression compression;
157 struct bch_acct_snapshot snapshot;
158 struct bch_acct_btree btree;
159 struct bch_acct_rebalance_work rebalance_work;
160 struct bch_acct_inum inum;
161 } __packed;
162 } __packed;
163 struct bpos _pad;
164 };
165 };
166
167 #endif /* _BCACHEFS_DISK_ACCOUNTING_FORMAT_H */
168
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