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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2011 Red Hat, Inc.
4 *
5 * This file is released under the GPL.
6 */
7
8#ifndef _LINUX_DM_TRANSACTION_MANAGER_H
9#define _LINUX_DM_TRANSACTION_MANAGER_H
10
11#include "dm-block-manager.h"
12
13struct dm_transaction_manager;
14struct dm_space_map;
15
16/*----------------------------------------------------------------*/
17
18/*
19 * This manages the scope of a transaction. It also enforces immutability
20 * of the on-disk data structures by limiting access to writeable blocks.
21 *
22 * Clients should not fiddle with the block manager directly.
23 */
24
25void dm_tm_destroy(struct dm_transaction_manager *tm);
26
27/*
28 * The non-blocking version of a transaction manager is intended for use in
29 * fast path code that needs to do lookups e.g. a dm mapping function.
30 * You create the non-blocking variant from a normal tm. The interface is
31 * the same, except that most functions will just return -EWOULDBLOCK.
32 * Methods that return void yet may block should not be called on a clone
33 * viz. dm_tm_inc, dm_tm_dec. Call dm_tm_destroy() as you would with a normal
34 * tm when you've finished with it. You may not destroy the original prior
35 * to clones.
36 */
37struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real);
38
39/*
40 * We use a 2-phase commit here.
41 *
42 * i) Make all changes for the transaction *except* for the superblock.
43 * Then call dm_tm_pre_commit() to flush them to disk.
44 *
45 * ii) Lock your superblock. Update. Then call dm_tm_commit() which will
46 * unlock the superblock and flush it. No other blocks should be updated
47 * during this period. Care should be taken to never unlock a partially
48 * updated superblock; perform any operations that could fail *before* you
49 * take the superblock lock.
50 */
51int dm_tm_pre_commit(struct dm_transaction_manager *tm);
52int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *superblock);
53
54/*
55 * These methods are the only way to get hold of a writeable block.
56 */
57
58/*
59 * dm_tm_new_block() is pretty self-explanatory. Make sure you do actually
60 * write to the whole of @data before you unlock, otherwise you could get
61 * a data leak. (The other option is for tm_new_block() to zero new blocks
62 * before handing them out, which will be redundant in most, if not all,
63 * cases).
64 * Zeroes the new block and returns with write lock held.
65 */
66int dm_tm_new_block(struct dm_transaction_manager *tm,
67 struct dm_block_validator *v,
68 struct dm_block **result);
69
70/*
71 * dm_tm_shadow_block() allocates a new block and copies the data from @orig
72 * to it. It then decrements the reference count on original block. Use
73 * this to update the contents of a block in a data structure, don't
74 * confuse this with a clone - you shouldn't access the orig block after
75 * this operation. Because the tm knows the scope of the transaction it
76 * can optimise requests for a shadow of a shadow to a no-op. Don't forget
77 * to unlock when you've finished with the shadow.
78 *
79 * The @inc_children flag is used to tell the caller whether it needs to
80 * adjust reference counts for children. (Data in the block may refer to
81 * other blocks.)
82 *
83 * Shadowing implicitly drops a reference on @orig so you must not have
84 * it locked when you call this.
85 */
86int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
87 struct dm_block_validator *v,
88 struct dm_block **result, int *inc_children);
89
90/*
91 * Read access. You can lock any block you want. If there's a write lock
92 * on it outstanding then it'll block.
93 */
94int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
95 struct dm_block_validator *v,
96 struct dm_block **result);
97
98void dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b);
99
100/*
101 * Functions for altering the reference count of a block directly.
102 */
103void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b);
104void dm_tm_inc_range(struct dm_transaction_manager *tm, dm_block_t b, dm_block_t e);
105void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b);
106void dm_tm_dec_range(struct dm_transaction_manager *tm, dm_block_t b, dm_block_t e);
107
108/*
109 * Builds up runs of adjacent blocks, and then calls the given fn
110 * (typically dm_tm_inc/dec). Very useful when you have to perform
111 * the same tm operation on all values in a btree leaf.
112 */
113typedef void (*dm_tm_run_fn)(struct dm_transaction_manager *, dm_block_t, dm_block_t);
114void dm_tm_with_runs(struct dm_transaction_manager *tm,
115 const __le64 *value_le, unsigned int count, dm_tm_run_fn fn);
116
117int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b, uint32_t *result);
118
119/*
120 * Finds out if a given block is shared (ie. has a reference count higher
121 * than one).
122 */
123int dm_tm_block_is_shared(struct dm_transaction_manager *tm, dm_block_t b,
124 int *result);
125
126struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm);
127
128/*
129 * If you're using a non-blocking clone the tm will build up a list of
130 * requested blocks that weren't in core. This call will request those
131 * blocks to be prefetched.
132 */
133void dm_tm_issue_prefetches(struct dm_transaction_manager *tm);
134
135/*
136 * A little utility that ties the knot by producing a transaction manager
137 * that has a space map managed by the transaction manager...
138 *
139 * Returns a tm that has an open transaction to write the new disk sm.
140 * Caller should store the new sm root and commit.
141 *
142 * The superblock location is passed so the metadata space map knows it
143 * shouldn't be used.
144 */
145int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
146 struct dm_transaction_manager **tm,
147 struct dm_space_map **sm);
148
149int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
150 void *sm_root, size_t root_len,
151 struct dm_transaction_manager **tm,
152 struct dm_space_map **sm);
153
154#endif /* _LINUX_DM_TRANSACTION_MANAGER_H */
1/*
2 * Copyright (C) 2011 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#ifndef _LINUX_DM_TRANSACTION_MANAGER_H
8#define _LINUX_DM_TRANSACTION_MANAGER_H
9
10#include "dm-block-manager.h"
11
12struct dm_transaction_manager;
13struct dm_space_map;
14
15/*----------------------------------------------------------------*/
16
17/*
18 * This manages the scope of a transaction. It also enforces immutability
19 * of the on-disk data structures by limiting access to writeable blocks.
20 *
21 * Clients should not fiddle with the block manager directly.
22 */
23
24void dm_tm_destroy(struct dm_transaction_manager *tm);
25
26/*
27 * The non-blocking version of a transaction manager is intended for use in
28 * fast path code that needs to do lookups e.g. a dm mapping function.
29 * You create the non-blocking variant from a normal tm. The interface is
30 * the same, except that most functions will just return -EWOULDBLOCK.
31 * Methods that return void yet may block should not be called on a clone
32 * viz. dm_tm_inc, dm_tm_dec. Call dm_tm_destroy() as you would with a normal
33 * tm when you've finished with it. You may not destroy the original prior
34 * to clones.
35 */
36struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real);
37
38/*
39 * We use a 2-phase commit here.
40 *
41 * i) Make all changes for the transaction *except* for the superblock.
42 * Then call dm_tm_pre_commit() to flush them to disk.
43 *
44 * ii) Lock your superblock. Update. Then call dm_tm_commit() which will
45 * unlock the superblock and flush it. No other blocks should be updated
46 * during this period. Care should be taken to never unlock a partially
47 * updated superblock; perform any operations that could fail *before* you
48 * take the superblock lock.
49 */
50int dm_tm_pre_commit(struct dm_transaction_manager *tm);
51int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *superblock);
52
53/*
54 * These methods are the only way to get hold of a writeable block.
55 */
56
57/*
58 * dm_tm_new_block() is pretty self-explanatory. Make sure you do actually
59 * write to the whole of @data before you unlock, otherwise you could get
60 * a data leak. (The other option is for tm_new_block() to zero new blocks
61 * before handing them out, which will be redundant in most, if not all,
62 * cases).
63 * Zeroes the new block and returns with write lock held.
64 */
65int dm_tm_new_block(struct dm_transaction_manager *tm,
66 struct dm_block_validator *v,
67 struct dm_block **result);
68
69/*
70 * dm_tm_shadow_block() allocates a new block and copies the data from @orig
71 * to it. It then decrements the reference count on original block. Use
72 * this to update the contents of a block in a data structure, don't
73 * confuse this with a clone - you shouldn't access the orig block after
74 * this operation. Because the tm knows the scope of the transaction it
75 * can optimise requests for a shadow of a shadow to a no-op. Don't forget
76 * to unlock when you've finished with the shadow.
77 *
78 * The @inc_children flag is used to tell the caller whether it needs to
79 * adjust reference counts for children. (Data in the block may refer to
80 * other blocks.)
81 *
82 * Shadowing implicitly drops a reference on @orig so you must not have
83 * it locked when you call this.
84 */
85int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
86 struct dm_block_validator *v,
87 struct dm_block **result, int *inc_children);
88
89/*
90 * Read access. You can lock any block you want. If there's a write lock
91 * on it outstanding then it'll block.
92 */
93int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
94 struct dm_block_validator *v,
95 struct dm_block **result);
96
97void dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b);
98
99/*
100 * Functions for altering the reference count of a block directly.
101 */
102void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b);
103
104void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b);
105
106int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
107 uint32_t *result);
108
109struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm);
110
111/*
112 * If you're using a non-blocking clone the tm will build up a list of
113 * requested blocks that weren't in core. This call will request those
114 * blocks to be prefetched.
115 */
116void dm_tm_issue_prefetches(struct dm_transaction_manager *tm);
117
118/*
119 * A little utility that ties the knot by producing a transaction manager
120 * that has a space map managed by the transaction manager...
121 *
122 * Returns a tm that has an open transaction to write the new disk sm.
123 * Caller should store the new sm root and commit.
124 *
125 * The superblock location is passed so the metadata space map knows it
126 * shouldn't be used.
127 */
128int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
129 struct dm_transaction_manager **tm,
130 struct dm_space_map **sm);
131
132int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
133 void *sm_root, size_t root_len,
134 struct dm_transaction_manager **tm,
135 struct dm_space_map **sm);
136
137#endif /* _LINUX_DM_TRANSACTION_MANAGER_H */