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