drivers/md/dm-bio-prison.h

   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;
  30         dm_thin_id dev;
  31         dm_block_t block;
  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
  63 struct dm_deferred_set *dm_deferred_set_create(void);
  64 void dm_deferred_set_destroy(struct dm_deferred_set *ds);
  65
  66 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
  67 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
  68 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
  69
  70 /*----------------------------------------------------------------*/
  71
  72 #endif