139 lines
4.4 KiB
C
139 lines
4.4 KiB
C
/*
|
|
* Copyright (C) 2011-2012 Red Hat, Inc.
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#ifndef DM_BIO_PRISON_H
|
|
#define DM_BIO_PRISON_H
|
|
|
|
#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
|
|
#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
|
|
|
|
#include <linux/bio.h>
|
|
#include <linux/rbtree.h>
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Sometimes we can't deal with a bio straight away. We put them in prison
|
|
* where they can't cause any mischief. Bios are put in a cell identified
|
|
* by a key, multiple bios can be in the same cell. When the cell is
|
|
* subsequently unlocked the bios become available.
|
|
*/
|
|
struct dm_bio_prison;
|
|
|
|
/*
|
|
* Keys define a range of blocks within either a virtual or physical
|
|
* device.
|
|
*/
|
|
struct dm_cell_key {
|
|
int virtual;
|
|
dm_thin_id dev;
|
|
dm_block_t block_begin, block_end;
|
|
};
|
|
|
|
/*
|
|
* Treat this as opaque, only in header so callers can manage allocation
|
|
* themselves.
|
|
*/
|
|
struct dm_bio_prison_cell {
|
|
struct list_head user_list; /* for client use */
|
|
struct rb_node node;
|
|
|
|
struct dm_cell_key key;
|
|
struct bio *holder;
|
|
struct bio_list bios;
|
|
};
|
|
|
|
struct dm_bio_prison *dm_bio_prison_create(void);
|
|
void dm_bio_prison_destroy(struct dm_bio_prison *prison);
|
|
|
|
/*
|
|
* These two functions just wrap a mempool. This is a transitory step:
|
|
* Eventually all bio prison clients should manage their own cell memory.
|
|
*
|
|
* Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
|
|
* in interrupt context or passed GFP_NOWAIT.
|
|
*/
|
|
struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,
|
|
gfp_t gfp);
|
|
void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
|
|
struct dm_bio_prison_cell *cell);
|
|
|
|
/*
|
|
* Creates, or retrieves a cell that overlaps the given key.
|
|
*
|
|
* Returns 1 if pre-existing cell returned, zero if new cell created using
|
|
* @cell_prealloc.
|
|
*/
|
|
int dm_get_cell(struct dm_bio_prison *prison,
|
|
struct dm_cell_key *key,
|
|
struct dm_bio_prison_cell *cell_prealloc,
|
|
struct dm_bio_prison_cell **cell_result);
|
|
|
|
/*
|
|
* An atomic op that combines retrieving or creating a cell, and adding a
|
|
* bio to it.
|
|
*
|
|
* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
|
|
*/
|
|
int dm_bio_detain(struct dm_bio_prison *prison,
|
|
struct dm_cell_key *key,
|
|
struct bio *inmate,
|
|
struct dm_bio_prison_cell *cell_prealloc,
|
|
struct dm_bio_prison_cell **cell_result);
|
|
|
|
void dm_cell_release(struct dm_bio_prison *prison,
|
|
struct dm_bio_prison_cell *cell,
|
|
struct bio_list *bios);
|
|
void dm_cell_release_no_holder(struct dm_bio_prison *prison,
|
|
struct dm_bio_prison_cell *cell,
|
|
struct bio_list *inmates);
|
|
void dm_cell_error(struct dm_bio_prison *prison,
|
|
struct dm_bio_prison_cell *cell, int error);
|
|
|
|
/*
|
|
* Visits the cell and then releases. Guarantees no new inmates are
|
|
* inserted between the visit and release.
|
|
*/
|
|
void dm_cell_visit_release(struct dm_bio_prison *prison,
|
|
void (*visit_fn)(void *, struct dm_bio_prison_cell *),
|
|
void *context, struct dm_bio_prison_cell *cell);
|
|
|
|
/*
|
|
* Rather than always releasing the prisoners in a cell, the client may
|
|
* want to promote one of them to be the new holder. There is a race here
|
|
* though between releasing an empty cell, and other threads adding new
|
|
* inmates. So this function makes the decision with its lock held.
|
|
*
|
|
* This function can have two outcomes:
|
|
* i) An inmate is promoted to be the holder of the cell (return value of 0).
|
|
* ii) The cell has no inmate for promotion and is released (return value of 1).
|
|
*/
|
|
int dm_cell_promote_or_release(struct dm_bio_prison *prison,
|
|
struct dm_bio_prison_cell *cell);
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* We use the deferred set to keep track of pending reads to shared blocks.
|
|
* We do this to ensure the new mapping caused by a write isn't performed
|
|
* until these prior reads have completed. Otherwise the insertion of the
|
|
* new mapping could free the old block that the read bios are mapped to.
|
|
*/
|
|
|
|
struct dm_deferred_set;
|
|
struct dm_deferred_entry;
|
|
|
|
struct dm_deferred_set *dm_deferred_set_create(void);
|
|
void dm_deferred_set_destroy(struct dm_deferred_set *ds);
|
|
|
|
struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
|
|
void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
|
|
int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
#endif
|