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 {
38 struct list_head user_list; /* for client use */
41 struct dm_cell_key key;
46 struct dm_bio_prison *dm_bio_prison_create(void);
47 void dm_bio_prison_destroy(struct dm_bio_prison *prison);
50 * These two functions just wrap a mempool. This is a transitory step:
51 * Eventually all bio prison clients should manage their own cell memory.
53 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
54 * in interrupt context or passed GFP_NOWAIT.
56 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,
58 void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
59 struct dm_bio_prison_cell *cell);
62 * Creates, or retrieves a cell for the given key.
64 * Returns 1 if pre-existing cell returned, zero if new cell created using
67 int dm_get_cell(struct dm_bio_prison *prison,
68 struct dm_cell_key *key,
69 struct dm_bio_prison_cell *cell_prealloc,
70 struct dm_bio_prison_cell **cell_result);
73 * An atomic op that combines retrieving a cell, and adding a bio to it.
75 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
77 int dm_bio_detain(struct dm_bio_prison *prison,
78 struct dm_cell_key *key,
80 struct dm_bio_prison_cell *cell_prealloc,
81 struct dm_bio_prison_cell **cell_result);
83 void dm_cell_release(struct dm_bio_prison *prison,
84 struct dm_bio_prison_cell *cell,
85 struct bio_list *bios);
86 void dm_cell_release_no_holder(struct dm_bio_prison *prison,
87 struct dm_bio_prison_cell *cell,
88 struct bio_list *inmates);
89 void dm_cell_error(struct dm_bio_prison *prison,
90 struct dm_bio_prison_cell *cell, int error);
92 /*----------------------------------------------------------------*/
95 * We use the deferred set to keep track of pending reads to shared blocks.
96 * We do this to ensure the new mapping caused by a write isn't performed
97 * until these prior reads have completed. Otherwise the insertion of the
98 * new mapping could free the old block that the read bios are mapped to.
101 struct dm_deferred_set;
102 struct dm_deferred_entry;
104 struct dm_deferred_set *dm_deferred_set_create(void);
105 void dm_deferred_set_destroy(struct dm_deferred_set *ds);
107 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
108 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
109 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
111 /*----------------------------------------------------------------*/