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Linux kernel mirror (for testing)
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1/*
2 * Copyright (C) 2011-2012 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/list.h>
14#include <linux/bio.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;
25struct dm_bio_prison_cell;
26
27/* FIXME: this needs to be more abstract */
28struct dm_cell_key {
29 int virtual;
30 dm_thin_id dev;
31 dm_block_t block;
32};
33
34struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
35void dm_bio_prison_destroy(struct dm_bio_prison *prison);
36
37/*
38 * This may block if a new cell needs allocating. You must ensure that
39 * cells will be unlocked even if the calling thread is blocked.
40 *
41 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
42 */
43int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
44 struct bio *inmate, struct dm_bio_prison_cell **ref);
45
46void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios);
47void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates);
48void dm_cell_error(struct dm_bio_prison_cell *cell);
49
50/*----------------------------------------------------------------*/
51
52/*
53 * We use the deferred set to keep track of pending reads to shared blocks.
54 * We do this to ensure the new mapping caused by a write isn't performed
55 * until these prior reads have completed. Otherwise the insertion of the
56 * new mapping could free the old block that the read bios are mapped to.
57 */
58
59struct dm_deferred_set;
60struct dm_deferred_entry;
61
62struct dm_deferred_set *dm_deferred_set_create(void);
63void dm_deferred_set_destroy(struct dm_deferred_set *ds);
64
65struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
66void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
67int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
68
69/*----------------------------------------------------------------*/
70
71#endif