/* * 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