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dm-bio-prison.h
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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  */
24 struct dm_bio_prison;
25 struct dm_bio_prison_cell;
26 
27 /* FIXME: this needs to be more abstract */
28 struct dm_cell_key {
29  int virtual;
32 };
33 
34 struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
35 void 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  */
43 int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
44  struct bio *inmate, struct dm_bio_prison_cell **ref);
45 
46 void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios);
47 void dm_cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio); // FIXME: bio arg not needed
48 void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates);
49 void dm_cell_error(struct dm_bio_prison_cell *cell);
50 
51 /*----------------------------------------------------------------*/
52 
53 /*
54  * We use the deferred set to keep track of pending reads to shared blocks.
55  * We do this to ensure the new mapping caused by a write isn't performed
56  * until these prior reads have completed. Otherwise the insertion of the
57  * new mapping could free the old block that the read bios are mapped to.
58  */
59 
60 struct dm_deferred_set;
61 struct dm_deferred_entry;
62 
65 
69 
70 /*----------------------------------------------------------------*/
71 
72 #endif