2 * Copyright (C) 2011-2012 Red Hat, Inc.
4 * This file is released under the GPL.
7 #ifndef DM_BIO_PRISON_H
8 #define DM_BIO_PRISON_H
10 #include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
11 #include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
13 #include <linux/list.h>
14 #include <linux/bio.h>
16 /*----------------------------------------------------------------*/
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.
25 struct dm_bio_prison_cell;
27 /* FIXME: this needs to be more abstract */
34 struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
35 void dm_bio_prison_destroy(struct dm_bio_prison *prison);
38 * These two functions just wrap a mempool. This is a transitory step:
39 * Eventually all bio prison clients should manage their own cell memory.
41 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
42 * in interrupt context or passed GFP_NOWAIT.
44 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,
46 void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
47 struct dm_bio_prison_cell *cell);
50 * An atomic op that combines retrieving a cell, and adding a bio to it.
52 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
54 int dm_bio_detain(struct dm_bio_prison *prison,
55 struct dm_cell_key *key,
57 struct dm_bio_prison_cell *cell_prealloc,
58 struct dm_bio_prison_cell **cell_result);
60 void dm_cell_release(struct dm_bio_prison *prison,
61 struct dm_bio_prison_cell *cell,
62 struct bio_list *bios);
63 void dm_cell_release_no_holder(struct dm_bio_prison *prison,
64 struct dm_bio_prison_cell *cell,
65 struct bio_list *inmates);
66 void dm_cell_error(struct dm_bio_prison *prison,
67 struct dm_bio_prison_cell *cell);
69 /*----------------------------------------------------------------*/
72 * We use the deferred set to keep track of pending reads to shared blocks.
73 * We do this to ensure the new mapping caused by a write isn't performed
74 * until these prior reads have completed. Otherwise the insertion of the
75 * new mapping could free the old block that the read bios are mapped to.
78 struct dm_deferred_set;
79 struct dm_deferred_entry;
81 struct dm_deferred_set *dm_deferred_set_create(void);
82 void dm_deferred_set_destroy(struct dm_deferred_set *ds);
84 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
85 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
86 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
88 /*----------------------------------------------------------------*/