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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.
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 hlist_node list
;
39 struct dm_cell_key key
;
44 struct dm_bio_prison
*dm_bio_prison_create(unsigned nr_cells
);
45 void dm_bio_prison_destroy(struct dm_bio_prison
*prison
);
48 * These two functions just wrap a mempool. This is a transitory step:
49 * Eventually all bio prison clients should manage their own cell memory.
51 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
52 * in interrupt context or passed GFP_NOWAIT.
54 struct dm_bio_prison_cell
*dm_bio_prison_alloc_cell(struct dm_bio_prison
*prison
,
56 void dm_bio_prison_free_cell(struct dm_bio_prison
*prison
,
57 struct dm_bio_prison_cell
*cell
);
60 * An atomic op that combines retrieving a cell, and adding a bio to it.
62 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
64 int dm_bio_detain(struct dm_bio_prison
*prison
,
65 struct dm_cell_key
*key
,
67 struct dm_bio_prison_cell
*cell_prealloc
,
68 struct dm_bio_prison_cell
**cell_result
);
70 void dm_cell_release(struct dm_bio_prison
*prison
,
71 struct dm_bio_prison_cell
*cell
,
72 struct bio_list
*bios
);
73 void dm_cell_release_no_holder(struct dm_bio_prison
*prison
,
74 struct dm_bio_prison_cell
*cell
,
75 struct bio_list
*inmates
);
76 void dm_cell_error(struct dm_bio_prison
*prison
,
77 struct dm_bio_prison_cell
*cell
);
79 /*----------------------------------------------------------------*/
82 * We use the deferred set to keep track of pending reads to shared blocks.
83 * We do this to ensure the new mapping caused by a write isn't performed
84 * until these prior reads have completed. Otherwise the insertion of the
85 * new mapping could free the old block that the read bios are mapped to.
88 struct dm_deferred_set
;
89 struct dm_deferred_entry
;
91 struct dm_deferred_set
*dm_deferred_set_create(void);
92 void dm_deferred_set_destroy(struct dm_deferred_set
*ds
);
94 struct dm_deferred_entry
*dm_deferred_entry_inc(struct dm_deferred_set
*ds
);
95 void dm_deferred_entry_dec(struct dm_deferred_entry
*entry
, struct list_head
*head
);
96 int dm_deferred_set_add_work(struct dm_deferred_set
*ds
, struct list_head
*work
);
98 /*----------------------------------------------------------------*/