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_V2_H
8#define DM_BIO_PRISON_V2_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#include <linux/workqueue.h>
16
17/*----------------------------------------------------------------*/
18
19int dm_bio_prison_init_v2(void);
20void dm_bio_prison_exit_v2(void);
21
22/*
23 * Sometimes we can't deal with a bio straight away.  We put them in prison
24 * where they can't cause any mischief.  Bios are put in a cell identified
25 * by a key, multiple bios can be in the same cell.  When the cell is
26 * subsequently unlocked the bios become available.
27 */
28struct dm_bio_prison_v2;
29
30/*
31 * Keys define a range of blocks within either a virtual or physical
32 * device.
33 */
34struct dm_cell_key_v2 {
35	int virtual;
36	dm_thin_id dev;
37	dm_block_t block_begin, block_end;
38};
39
40/*
41 * Treat this as opaque, only in header so callers can manage allocation
42 * themselves.
43 */
44struct dm_bio_prison_cell_v2 {
45	// FIXME: pack these
46	bool exclusive_lock;
47	unsigned exclusive_level;
48	unsigned shared_count;
49	struct work_struct *quiesce_continuation;
50
51	struct rb_node node;
52	struct dm_cell_key_v2 key;
53	struct bio_list bios;
54};
55
56struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq);
57void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *prison);
58
59/*
60 * These two functions just wrap a mempool.  This is a transitory step:
61 * Eventually all bio prison clients should manage their own cell memory.
62 *
63 * Like mempool_alloc(), dm_bio_prison_alloc_cell_v2() can only fail if called
64 * in interrupt context or passed GFP_NOWAIT.
65 */
66struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison,
67						    gfp_t gfp);
68void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison,
69				struct dm_bio_prison_cell_v2 *cell);
70
71/*
72 * Shared locks have a bio associated with them.
73 *
74 * If the lock is granted the caller can continue to use the bio, and must
75 * call dm_cell_put_v2() to drop the reference count when finished using it.
76 *
77 * If the lock cannot be granted then the bio will be tracked within the
78 * cell, and later given to the holder of the exclusive lock.
79 *
80 * See dm_cell_lock_v2() for discussion of the lock_level parameter.
81 *
82 * Compare *cell_result with cell_prealloc to see if the prealloc was used.
83 * If cell_prealloc was used then inmate wasn't added to it.
84 *
85 * Returns true if the lock is granted.
86 */
87bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison,
88		    struct dm_cell_key_v2 *key,
89		    unsigned lock_level,
90		    struct bio *inmate,
91		    struct dm_bio_prison_cell_v2 *cell_prealloc,
92		    struct dm_bio_prison_cell_v2 **cell_result);
93
94/*
95 * Decrement the shared reference count for the lock.  Returns true if
96 * returning ownership of the cell (ie. you should free it).
97 */
98bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison,
99		    struct dm_bio_prison_cell_v2 *cell);
100
101/*
102 * Locks a cell.  No associated bio.  Exclusive locks get priority.  These
103 * locks constrain whether the io locks are granted according to level.
104 *
105 * Shared locks will still be granted if the lock_level is > (not = to) the
106 * exclusive lock level.
107 *
108 * If an _exclusive_ lock is already held then -EBUSY is returned.
109 *
110 * Return values:
111 *  < 0 - error
112 *  0   - locked; no quiescing needed
113 *  1   - locked; quiescing needed
114 */
115int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison,
116		    struct dm_cell_key_v2 *key,
117		    unsigned lock_level,
118		    struct dm_bio_prison_cell_v2 *cell_prealloc,
119		    struct dm_bio_prison_cell_v2 **cell_result);
120
121void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison,
122			struct dm_bio_prison_cell_v2 *cell,
123			struct work_struct *continuation);
124
125/*
126 * Promotes an _exclusive_ lock to a higher lock level.
127 *
128 * Return values:
129 *  < 0 - error
130 *  0   - promoted; no quiescing needed
131 *  1   - promoted; quiescing needed
132 */
133int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison,
134			    struct dm_bio_prison_cell_v2 *cell,
135			    unsigned new_lock_level);
136
137/*
138 * Adds any held bios to the bio list.
139 *
140 * There may be shared locks still held at this point even if you quiesced
141 * (ie. different lock levels).
142 *
143 * Returns true if returning ownership of the cell (ie. you should free
144 * it).
145 */
146bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison,
147		       struct dm_bio_prison_cell_v2 *cell,
148		       struct bio_list *bios);
149
150/*----------------------------------------------------------------*/
151
152#endif
153