/*
* Copyright (C) 2011-2017 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#ifndef DM_BIO_PRISON_V2_H
#define DM_BIO_PRISON_V2_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>
#include <linux/workqueue.h>
/*----------------------------------------------------------------*/
int dm_bio_prison_init_v2(void);
void dm_bio_prison_exit_v2(void);
/*
* 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_v2;
/*
* Keys define a range of blocks within either a virtual or physical
* device.
*/
struct dm_cell_key_v2 {
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_v2 {
// FIXME: pack these
bool exclusive_lock;
unsigned exclusive_level;
unsigned shared_count;
struct work_struct *quiesce_continuation;
struct rb_node node;
struct dm_cell_key_v2 key;
struct bio_list bios;
};
struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq);
void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *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_v2() can only fail if called
* in interrupt context or passed GFP_NOWAIT.
*/
struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison,
gfp_t gfp);
void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison,
struct dm_bio_prison_cell_v2 *cell);
/*
* Shared locks have a bio associated with them.
*
* If the lock is granted the caller can continue to use the bio, and must
* call dm_cell_put_v2() to drop the reference count when finished using it.
*
* If the lock cannot be granted then the bio will be tracked within the
* cell, and later given to the holder of the exclusive lock.
*
* See dm_cell_lock_v2() for discussion of the lock_level parameter.
*
* Compare *cell_result with cell_prealloc to see if the prealloc was used.
* If cell_prealloc was used then inmate wasn't added to it.
*
* Returns true if the lock is granted.
*/
bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison,
struct dm_cell_key_v2 *key,
unsigned lock_level,
struct bio *inmate,
struct dm_bio_prison_cell_v2 *cell_prealloc,
struct dm_bio_prison_cell_v2 **cell_result);
/*
* Decrement the shared reference count for the lock. Returns true if
* returning ownership of the cell (ie. you should free it).
*/
bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison,
struct dm_bio_prison_cell_v2 *cell);
/*
* Locks a cell. No associated bio. Exclusive locks get priority. These
* locks constrain whether the io locks are granted according to level.
*
* Shared locks will still be granted if the lock_level is > (not = to) the
* exclusive lock level.
*
* If an _exclusive_ lock is already held then -EBUSY is returned.
*
* Return values:
* < 0 - error
* 0 - locked; no quiescing needed
* 1 - locked; quiescing needed
*/
int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison,
struct dm_cell_key_v2 *key,
unsigned lock_level,
struct dm_bio_prison_cell_v2 *cell_prealloc,
struct dm_bio_prison_cell_v2 **cell_result);
void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison,
struct dm_bio_prison_cell_v2 *cell,
struct work_struct *continuation);
/*
* Promotes an _exclusive_ lock to a higher lock level.
*
* Return values:
* < 0 - error
* 0 - promoted; no quiescing needed
* 1 - promoted; quiescing needed
*/
int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison,
struct dm_bio_prison_cell_v2 *cell,
unsigned new_lock_level);
/*
* Adds any held bios to the bio list.
*
* There may be shared locks still held at this point even if you quiesced
* (ie. different lock levels).
*
* Returns true if returning ownership of the cell (ie. you should free
* it).
*/
bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison,
struct dm_bio_prison_cell_v2 *cell,
struct bio_list *bios);
/*----------------------------------------------------------------*/
#endif
