153 lines
4.5 KiB
C
153 lines
4.5 KiB
C
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/*
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* Copyright (C) 2011-2017 Red Hat, Inc.
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*
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* This file is released under the GPL.
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*/
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#ifndef DM_BIO_PRISON_V2_H
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#define DM_BIO_PRISON_V2_H
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#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
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#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
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#include <linux/bio.h>
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#include <linux/rbtree.h>
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#include <linux/workqueue.h>
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/*----------------------------------------------------------------*/
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int dm_bio_prison_init_v2(void);
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void dm_bio_prison_exit_v2(void);
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/*
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* Sometimes we can't deal with a bio straight away. We put them in prison
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* where they can't cause any mischief. Bios are put in a cell identified
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* by a key, multiple bios can be in the same cell. When the cell is
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* subsequently unlocked the bios become available.
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*/
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struct dm_bio_prison_v2;
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/*
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* Keys define a range of blocks within either a virtual or physical
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* device.
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*/
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struct dm_cell_key_v2 {
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int virtual;
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dm_thin_id dev;
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dm_block_t block_begin, block_end;
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};
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/*
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* Treat this as opaque, only in header so callers can manage allocation
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* themselves.
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*/
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struct dm_bio_prison_cell_v2 {
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// FIXME: pack these
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bool exclusive_lock;
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unsigned exclusive_level;
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unsigned shared_count;
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struct work_struct *quiesce_continuation;
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struct rb_node node;
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struct dm_cell_key_v2 key;
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struct bio_list bios;
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};
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struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq);
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void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *prison);
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/*
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* These two functions just wrap a mempool. This is a transitory step:
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* Eventually all bio prison clients should manage their own cell memory.
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*
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* Like mempool_alloc(), dm_bio_prison_alloc_cell_v2() can only fail if called
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* in interrupt context or passed GFP_NOWAIT.
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*/
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struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison,
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gfp_t gfp);
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void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell);
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/*
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* Shared locks have a bio associated with them.
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*
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* If the lock is granted the caller can continue to use the bio, and must
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* call dm_cell_put_v2() to drop the reference count when finished using it.
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*
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* If the lock cannot be granted then the bio will be tracked within the
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* cell, and later given to the holder of the exclusive lock.
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*
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* See dm_cell_lock_v2() for discussion of the lock_level parameter.
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*
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* Compare *cell_result with cell_prealloc to see if the prealloc was used.
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* If cell_prealloc was used then inmate wasn't added to it.
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*
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* Returns true if the lock is granted.
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*/
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bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison,
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struct dm_cell_key_v2 *key,
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unsigned lock_level,
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struct bio *inmate,
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struct dm_bio_prison_cell_v2 *cell_prealloc,
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struct dm_bio_prison_cell_v2 **cell_result);
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/*
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* Decrement the shared reference count for the lock. Returns true if
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* returning ownership of the cell (ie. you should free it).
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*/
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bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell);
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/*
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* Locks a cell. No associated bio. Exclusive locks get priority. These
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* locks constrain whether the io locks are granted according to level.
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*
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* Shared locks will still be granted if the lock_level is > (not = to) the
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* exclusive lock level.
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*
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* If an _exclusive_ lock is already held then -EBUSY is returned.
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*
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* Return values:
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* < 0 - error
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* 0 - locked; no quiescing needed
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* 1 - locked; quiescing needed
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*/
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int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison,
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struct dm_cell_key_v2 *key,
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unsigned lock_level,
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struct dm_bio_prison_cell_v2 *cell_prealloc,
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struct dm_bio_prison_cell_v2 **cell_result);
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void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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struct work_struct *continuation);
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/*
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* Promotes an _exclusive_ lock to a higher lock level.
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*
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* Return values:
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* < 0 - error
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* 0 - promoted; no quiescing needed
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* 1 - promoted; quiescing needed
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*/
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int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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unsigned new_lock_level);
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/*
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* Adds any held bios to the bio list.
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*
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* There may be shared locks still held at this point even if you quiesced
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* (ie. different lock levels).
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*
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* Returns true if returning ownership of the cell (ie. you should free
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* it).
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*/
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bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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struct bio_list *bios);
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/*----------------------------------------------------------------*/
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#endif
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