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/bio.h>
14 #include <linux/rbtree.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.
26 /* FIXME: this needs to be more abstract */
34 * Treat this as opaque, only in header so callers can manage allocation
37 struct dm_bio_prison_cell {
40 struct dm_cell_key key;
45 struct dm_bio_prison *dm_bio_prison_create(void);
46 void dm_bio_prison_destroy(struct dm_bio_prison *prison);
49 * These two functions just wrap a mempool. This is a transitory step:
50 * Eventually all bio prison clients should manage their own cell memory.
52 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
53 * in interrupt context or passed GFP_NOWAIT.
55 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,
57 void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
58 struct dm_bio_prison_cell *cell);
61 * Creates, or retrieves a cell for the given key.
63 * Returns 1 if pre-existing cell returned, zero if new cell created using
66 int dm_get_cell(struct dm_bio_prison *prison,
67 struct dm_cell_key *key,
68 struct dm_bio_prison_cell *cell_prealloc,
69 struct dm_bio_prison_cell **cell_result);
72 * An atomic op that combines retrieving a cell, and adding a bio to it.
74 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
76 int dm_bio_detain(struct dm_bio_prison *prison,
77 struct dm_cell_key *key,
79 struct dm_bio_prison_cell *cell_prealloc,
80 struct dm_bio_prison_cell **cell_result);
82 void dm_cell_release(struct dm_bio_prison *prison,
83 struct dm_bio_prison_cell *cell,
84 struct bio_list *bios);
85 void dm_cell_release_no_holder(struct dm_bio_prison *prison,
86 struct dm_bio_prison_cell *cell,
87 struct bio_list *inmates);
88 void dm_cell_error(struct dm_bio_prison *prison,
89 struct dm_bio_prison_cell *cell, int error);
91 /*----------------------------------------------------------------*/
94 * We use the deferred set to keep track of pending reads to shared blocks.
95 * We do this to ensure the new mapping caused by a write isn't performed
96 * until these prior reads have completed. Otherwise the insertion of the
97 * new mapping could free the old block that the read bios are mapped to.
100 struct dm_deferred_set;
101 struct dm_deferred_entry;
103 struct dm_deferred_set *dm_deferred_set_create(void);
104 void dm_deferred_set_destroy(struct dm_deferred_set *ds);
106 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
107 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
108 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
110 /*----------------------------------------------------------------*/