linux/drivers/md/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 */
  24struct dm_bio_prison;
  25struct dm_bio_prison_cell;
  26
  27/* FIXME: this needs to be more abstract */
  28struct dm_cell_key {
  29        int virtual;
  30        dm_thin_id dev;
  31        dm_block_t block;
  32};
  33
  34struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
  35void 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 */
  43int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
  44                  struct bio *inmate, struct dm_bio_prison_cell **ref);
  45
  46void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios);
  47void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates);
  48void dm_cell_error(struct dm_bio_prison_cell *cell);
  49
  50/*----------------------------------------------------------------*/
  51
  52/*
  53 * We use the deferred set to keep track of pending reads to shared blocks.
  54 * We do this to ensure the new mapping caused by a write isn't performed
  55 * until these prior reads have completed.  Otherwise the insertion of the
  56 * new mapping could free the old block that the read bios are mapped to.
  57 */
  58
  59struct dm_deferred_set;
  60struct dm_deferred_entry;
  61
  62struct dm_deferred_set *dm_deferred_set_create(void);
  63void dm_deferred_set_destroy(struct dm_deferred_set *ds);
  64
  65struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
  66void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
  67int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
  68
  69/*----------------------------------------------------------------*/
  70
  71#endif
  72
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