Loading...
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2011-2017 Red Hat, Inc.
4 *
5 * This file is released under the GPL.
6 */
7
8#ifndef DM_BIO_PRISON_H
9#define DM_BIO_PRISON_H
10
11#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
12#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
13
14#include <linux/bio.h>
15#include <linux/rbtree.h>
16
17/*----------------------------------------------------------------*/
18
19/*
20 * Sometimes we can't deal with a bio straight away. We put them in prison
21 * where they can't cause any mischief. Bios are put in a cell identified
22 * by a key, multiple bios can be in the same cell. When the cell is
23 * subsequently unlocked the bios become available.
24 */
25struct dm_bio_prison;
26
27/*
28 * Keys define a range of blocks within either a virtual or physical
29 * device.
30 */
31struct dm_cell_key {
32 int virtual;
33 dm_thin_id dev;
34 dm_block_t block_begin, block_end;
35};
36
37/*
38 * The range of a key (block_end - block_begin) must not
39 * exceed BIO_PRISON_MAX_RANGE. Also the range must not
40 * cross a similarly sized boundary.
41 *
42 * Must be a power of 2.
43 */
44#define BIO_PRISON_MAX_RANGE 1024
45#define BIO_PRISON_MAX_RANGE_SHIFT 10
46
47/*
48 * Treat this as opaque, only in header so callers can manage allocation
49 * themselves.
50 */
51struct dm_bio_prison_cell {
52 struct list_head user_list; /* for client use */
53 struct rb_node node;
54
55 struct dm_cell_key key;
56 struct bio *holder;
57 struct bio_list bios;
58};
59
60struct dm_bio_prison *dm_bio_prison_create(void);
61void dm_bio_prison_destroy(struct dm_bio_prison *prison);
62
63/*
64 * These two functions just wrap a mempool. This is a transitory step:
65 * Eventually all bio prison clients should manage their own cell memory.
66 *
67 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
68 * in interrupt context or passed GFP_NOWAIT.
69 */
70struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,
71 gfp_t gfp);
72void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
73 struct dm_bio_prison_cell *cell);
74
75/*
76 * Creates, or retrieves a cell that overlaps the given key.
77 *
78 * Returns 1 if pre-existing cell returned, zero if new cell created using
79 * @cell_prealloc.
80 */
81int dm_get_cell(struct dm_bio_prison *prison,
82 struct dm_cell_key *key,
83 struct dm_bio_prison_cell *cell_prealloc,
84 struct dm_bio_prison_cell **cell_result);
85
86/*
87 * Returns false if key is beyond BIO_PRISON_MAX_RANGE or spans a boundary.
88 */
89bool dm_cell_key_has_valid_range(struct dm_cell_key *key);
90
91/*
92 * An atomic op that combines retrieving or creating a cell, and adding a
93 * bio to it.
94 *
95 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
96 */
97int dm_bio_detain(struct dm_bio_prison *prison,
98 struct dm_cell_key *key,
99 struct bio *inmate,
100 struct dm_bio_prison_cell *cell_prealloc,
101 struct dm_bio_prison_cell **cell_result);
102
103void dm_cell_release(struct dm_bio_prison *prison,
104 struct dm_bio_prison_cell *cell,
105 struct bio_list *bios);
106void dm_cell_release_no_holder(struct dm_bio_prison *prison,
107 struct dm_bio_prison_cell *cell,
108 struct bio_list *inmates);
109void dm_cell_error(struct dm_bio_prison *prison,
110 struct dm_bio_prison_cell *cell, blk_status_t error);
111
112/*
113 * Visits the cell and then releases. Guarantees no new inmates are
114 * inserted between the visit and release.
115 */
116void dm_cell_visit_release(struct dm_bio_prison *prison,
117 void (*visit_fn)(void *, struct dm_bio_prison_cell *),
118 void *context, struct dm_bio_prison_cell *cell);
119
120/*
121 * Rather than always releasing the prisoners in a cell, the client may
122 * want to promote one of them to be the new holder. There is a race here
123 * though between releasing an empty cell, and other threads adding new
124 * inmates. So this function makes the decision with its lock held.
125 *
126 * This function can have two outcomes:
127 * i) An inmate is promoted to be the holder of the cell (return value of 0).
128 * ii) The cell has no inmate for promotion and is released (return value of 1).
129 */
130int dm_cell_promote_or_release(struct dm_bio_prison *prison,
131 struct dm_bio_prison_cell *cell);
132
133/*----------------------------------------------------------------*/
134
135/*
136 * We use the deferred set to keep track of pending reads to shared blocks.
137 * We do this to ensure the new mapping caused by a write isn't performed
138 * until these prior reads have completed. Otherwise the insertion of the
139 * new mapping could free the old block that the read bios are mapped to.
140 */
141
142struct dm_deferred_set;
143struct dm_deferred_entry;
144
145struct dm_deferred_set *dm_deferred_set_create(void);
146void dm_deferred_set_destroy(struct dm_deferred_set *ds);
147
148struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
149void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
150int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
151
152/*----------------------------------------------------------------*/
153
154#endif
1/*
2 * Copyright (C) 2011-2017 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#ifndef DM_BIO_PRISON_H
8#define DM_BIO_PRISON_H
9
10#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
11#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
12
13#include <linux/bio.h>
14#include <linux/rbtree.h>
15
16/*----------------------------------------------------------------*/
17
18/*
19 * Sometimes we can't deal with a bio straight away. We put them in prison
20 * where they can't cause any mischief. Bios are put in a cell identified
21 * by a key, multiple bios can be in the same cell. When the cell is
22 * subsequently unlocked the bios become available.
23 */
24struct dm_bio_prison;
25
26/*
27 * Keys define a range of blocks within either a virtual or physical
28 * device.
29 */
30struct dm_cell_key {
31 int virtual;
32 dm_thin_id dev;
33 dm_block_t block_begin, block_end;
34};
35
36/*
37 * Treat this as opaque, only in header so callers can manage allocation
38 * themselves.
39 */
40struct dm_bio_prison_cell {
41 struct list_head user_list; /* for client use */
42 struct rb_node node;
43
44 struct dm_cell_key key;
45 struct bio *holder;
46 struct bio_list bios;
47};
48
49struct dm_bio_prison *dm_bio_prison_create(void);
50void dm_bio_prison_destroy(struct dm_bio_prison *prison);
51
52/*
53 * These two functions just wrap a mempool. This is a transitory step:
54 * Eventually all bio prison clients should manage their own cell memory.
55 *
56 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
57 * in interrupt context or passed GFP_NOWAIT.
58 */
59struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,
60 gfp_t gfp);
61void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
62 struct dm_bio_prison_cell *cell);
63
64/*
65 * Creates, or retrieves a cell that overlaps the given key.
66 *
67 * Returns 1 if pre-existing cell returned, zero if new cell created using
68 * @cell_prealloc.
69 */
70int dm_get_cell(struct dm_bio_prison *prison,
71 struct dm_cell_key *key,
72 struct dm_bio_prison_cell *cell_prealloc,
73 struct dm_bio_prison_cell **cell_result);
74
75/*
76 * An atomic op that combines retrieving or creating a cell, and adding a
77 * bio to it.
78 *
79 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
80 */
81int dm_bio_detain(struct dm_bio_prison *prison,
82 struct dm_cell_key *key,
83 struct bio *inmate,
84 struct dm_bio_prison_cell *cell_prealloc,
85 struct dm_bio_prison_cell **cell_result);
86
87void dm_cell_release(struct dm_bio_prison *prison,
88 struct dm_bio_prison_cell *cell,
89 struct bio_list *bios);
90void dm_cell_release_no_holder(struct dm_bio_prison *prison,
91 struct dm_bio_prison_cell *cell,
92 struct bio_list *inmates);
93void dm_cell_error(struct dm_bio_prison *prison,
94 struct dm_bio_prison_cell *cell, blk_status_t error);
95
96/*
97 * Visits the cell and then releases. Guarantees no new inmates are
98 * inserted between the visit and release.
99 */
100void dm_cell_visit_release(struct dm_bio_prison *prison,
101 void (*visit_fn)(void *, struct dm_bio_prison_cell *),
102 void *context, struct dm_bio_prison_cell *cell);
103
104/*
105 * Rather than always releasing the prisoners in a cell, the client may
106 * want to promote one of them to be the new holder. There is a race here
107 * though between releasing an empty cell, and other threads adding new
108 * inmates. So this function makes the decision with its lock held.
109 *
110 * This function can have two outcomes:
111 * i) An inmate is promoted to be the holder of the cell (return value of 0).
112 * ii) The cell has no inmate for promotion and is released (return value of 1).
113 */
114int dm_cell_promote_or_release(struct dm_bio_prison *prison,
115 struct dm_bio_prison_cell *cell);
116
117/*----------------------------------------------------------------*/
118
119/*
120 * We use the deferred set to keep track of pending reads to shared blocks.
121 * We do this to ensure the new mapping caused by a write isn't performed
122 * until these prior reads have completed. Otherwise the insertion of the
123 * new mapping could free the old block that the read bios are mapped to.
124 */
125
126struct dm_deferred_set;
127struct dm_deferred_entry;
128
129struct dm_deferred_set *dm_deferred_set_create(void);
130void dm_deferred_set_destroy(struct dm_deferred_set *ds);
131
132struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
133void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
134int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
135
136/*----------------------------------------------------------------*/
137
138#endif