[deliverable/linux.git] / drivers / md / dm-bio-prison.h

/*
 * 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;

/* FIXME: this needs to be more abstract */
struct dm_cell_key {
	int virtual;
	dm_thin_id dev;
	dm_block_t block;
};

/*
 * 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 for 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 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);

/*----------------------------------------------------------------*/

/*
 * 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
Commit	Line	Data
4f81a417 MS	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
4f81a417	13	#include <linux/bio.h>
a195db2d	14	#include <linux/rbtree.h>
4f81a417 MS	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;
4f81a417 MS	25
	26	/* FIXME: this needs to be more abstract */
	27	struct dm_cell_key {
	28	int virtual;
	29	dm_thin_id dev;
	30	dm_block_t block;
	31	};
	32
025b9685 JT	33	/*
	34	* Treat this as opaque, only in header so callers can manage allocation
	35	* themselves.
	36	*/
	37	struct dm_bio_prison_cell {
a374bb21	38	struct list_head user_list; /* for client use */
a195db2d JT	39	struct rb_node node;
a195db2d JT	40
025b9685 JT	41	struct dm_cell_key key;
	42	struct bio *holder;
	43	struct bio_list bios;
	44	};
	45
a195db2d	46	struct dm_bio_prison *dm_bio_prison_create(void);
4f81a417 MS	47	void dm_bio_prison_destroy(struct dm_bio_prison *prison);
	48
	49	/*
6beca5eb JT	50	* These two functions just wrap a mempool. This is a transitory step:
6beca5eb JT	51	* Eventually all bio prison clients should manage their own cell memory.
4f81a417	52	*
6beca5eb JT	53	* Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
6beca5eb JT	54	* in interrupt context or passed GFP_NOWAIT.
4f81a417	55	*/
6beca5eb JT	56	struct dm_bio_prison_cell dm_bio_prison_alloc_cell(struct dm_bio_prison prison,
	57	gfp_t gfp);
	58	void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
	59	struct dm_bio_prison_cell *cell);
4f81a417	60
c6b4fcba JT	61	/*
	62	* Creates, or retrieves a cell for the given key.
	63	*
	64	* Returns 1 if pre-existing cell returned, zero if new cell created using
	65	* @cell_prealloc.
	66	*/
	67	int dm_get_cell(struct dm_bio_prison *prison,
	68	struct dm_cell_key *key,
	69	struct dm_bio_prison_cell *cell_prealloc,
	70	struct dm_bio_prison_cell **cell_result);
	71
6beca5eb JT	72	/*
	73	* An atomic op that combines retrieving a cell, and adding a bio to it.
	74	*
	75	* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
	76	*/
	77	int dm_bio_detain(struct dm_bio_prison *prison,
	78	struct dm_cell_key *key,
	79	struct bio *inmate,
	80	struct dm_bio_prison_cell *cell_prealloc,
	81	struct dm_bio_prison_cell **cell_result);
	82
	83	void dm_cell_release(struct dm_bio_prison *prison,
	84	struct dm_bio_prison_cell *cell,
	85	struct bio_list *bios);
	86	void dm_cell_release_no_holder(struct dm_bio_prison *prison,
	87	struct dm_bio_prison_cell *cell,
	88	struct bio_list *inmates);
	89	void dm_cell_error(struct dm_bio_prison *prison,
af91805a	90	struct dm_bio_prison_cell *cell, int error);
4f81a417 MS	91
	92	/----------------------------------------------------------------/
	93
	94	/*
	95	* We use the deferred set to keep track of pending reads to shared blocks.
	96	* We do this to ensure the new mapping caused by a write isn't performed
	97	* until these prior reads have completed. Otherwise the insertion of the
	98	* new mapping could free the old block that the read bios are mapped to.
	99	*/
	100
	101	struct dm_deferred_set;
	102	struct dm_deferred_entry;
	103
	104	struct dm_deferred_set *dm_deferred_set_create(void);
	105	void dm_deferred_set_destroy(struct dm_deferred_set *ds);
	106
	107	struct dm_deferred_entry dm_deferred_entry_inc(struct dm_deferred_set ds);
	108	void dm_deferred_entry_dec(struct dm_deferred_entry entry, struct list_head head);
	109	int dm_deferred_set_add_work(struct dm_deferred_set ds, struct list_head work);
	110
	111	/----------------------------------------------------------------/
	112
	113	#endif