diff options
Diffstat (limited to 'drivers/md/dm-bio-prison-v2.h')
| -rw-r--r-- | drivers/md/dm-bio-prison-v2.h | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/drivers/md/dm-bio-prison-v2.h b/drivers/md/dm-bio-prison-v2.h new file mode 100644 index 000000000000..6e04234268db --- /dev/null +++ b/drivers/md/dm-bio-prison-v2.h @@ -0,0 +1,152 @@ +/* + * 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 |