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linux/drivers/md/dm.h
Joe Thornber 363b7fd76c dm: improve hash_locks sizing and hash function 
Both bufio and bio-prison-v1 use the identical model for splitting
their respective locks and rbtrees. Improve dm_num_hash_locks() to
distribute across more rbtrees to improve overall performance -- but
the maximum number of locks/rbtrees is still 64.

Also factor out a common hash function named dm_hash_locks_index(),
the magic numbers used were determined to be best using this program:
 https://gist.github.com/jthornber/e05c47daa7b500c56dc339269c5467fc

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
2023-03-30 15:57:51 -04:00

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/*
* Internal header file for device mapper
*
* Copyright (C) 2001, 2002 Sistina Software
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This file is released under the LGPL.
*/
#ifndef DM_INTERNAL_H
#define DM_INTERNAL_H
#include <linux/fs.h>
#include <linux/device-mapper.h>
#include <linux/list.h>
#include <linux/moduleparam.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/hdreg.h>
#include <linux/completion.h>
#include <linux/kobject.h>
#include <linux/refcount.h>
#include <linux/log2.h>
#include "dm-stats.h"
/*
* Suspend feature flags
*/
#define DM_SUSPEND_LOCKFS_FLAG (1 << 0)
#define DM_SUSPEND_NOFLUSH_FLAG (1 << 1)
/*
* Status feature flags
*/
#define DM_STATUS_NOFLUSH_FLAG (1 << 0)
/*
* List of devices that a metadevice uses and should open/close.
*/
struct dm_dev_internal {
struct list_head list;
refcount_t count;
struct dm_dev *dm_dev;
};
struct dm_table;
struct dm_md_mempools;
struct dm_target_io;
struct dm_io;
/*
*---------------------------------------------------------------
* Internal table functions.
*---------------------------------------------------------------
*/
void dm_table_event_callback(struct dm_table *t,
void (*fn)(void *), void *context);
struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector);
bool dm_table_has_no_data_devices(struct dm_table *table);
int dm_calculate_queue_limits(struct dm_table *table,
struct queue_limits *limits);
int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
struct queue_limits *limits);
struct list_head *dm_table_get_devices(struct dm_table *t);
void dm_table_presuspend_targets(struct dm_table *t);
void dm_table_presuspend_undo_targets(struct dm_table *t);
void dm_table_postsuspend_targets(struct dm_table *t);
int dm_table_resume_targets(struct dm_table *t);
enum dm_queue_mode dm_table_get_type(struct dm_table *t);
struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
struct dm_target *dm_table_get_immutable_target(struct dm_table *t);
struct dm_target *dm_table_get_wildcard_target(struct dm_table *t);
bool dm_table_bio_based(struct dm_table *t);
bool dm_table_request_based(struct dm_table *t);
void dm_lock_md_type(struct mapped_device *md);
void dm_unlock_md_type(struct mapped_device *md);
void dm_set_md_type(struct mapped_device *md, enum dm_queue_mode type);
enum dm_queue_mode dm_get_md_type(struct mapped_device *md);
struct target_type *dm_get_immutable_target_type(struct mapped_device *md);
int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t);
/*
* To check whether the target type is bio-based or not (request-based).
*/
#define dm_target_bio_based(t) ((t)->type->map != NULL)
/*
* To check whether the target type is request-based or not (bio-based).
*/
#define dm_target_request_based(t) ((t)->type->clone_and_map_rq != NULL)
/*
* To check whether the target type is a hybrid (capable of being
* either request-based or bio-based).
*/
#define dm_target_hybrid(t) (dm_target_bio_based(t) && dm_target_request_based(t))
/*
* Zoned targets related functions.
*/
int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q);
void dm_zone_endio(struct dm_io *io, struct bio *clone);
#ifdef CONFIG_BLK_DEV_ZONED
void dm_cleanup_zoned_dev(struct mapped_device *md);
int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
unsigned int nr_zones, report_zones_cb cb, void *data);
bool dm_is_zone_write(struct mapped_device *md, struct bio *bio);
int dm_zone_map_bio(struct dm_target_io *io);
#else
static inline void dm_cleanup_zoned_dev(struct mapped_device *md) {}
#define dm_blk_report_zones NULL
static inline bool dm_is_zone_write(struct mapped_device *md, struct bio *bio)
{
return false;
}
static inline int dm_zone_map_bio(struct dm_target_io *tio)
{
return DM_MAPIO_KILL;
}
#endif
/*
*---------------------------------------------------------------
* A registry of target types.
*---------------------------------------------------------------
*/
int dm_target_init(void);
void dm_target_exit(void);
struct target_type *dm_get_target_type(const char *name);
void dm_put_target_type(struct target_type *tt);
int dm_target_iterate(void (*iter_func)(struct target_type *tt,
void *param), void *param);
int dm_split_args(int *argc, char ***argvp, char *input);
/*
* Is this mapped_device being deleted?
*/
int dm_deleting_md(struct mapped_device *md);
/*
* Is this mapped_device suspended?
*/
int dm_suspended_md(struct mapped_device *md);
/*
* Internal suspend and resume methods.
*/
int dm_suspended_internally_md(struct mapped_device *md);
void dm_internal_suspend_fast(struct mapped_device *md);
void dm_internal_resume_fast(struct mapped_device *md);
void dm_internal_suspend_noflush(struct mapped_device *md);
void dm_internal_resume(struct mapped_device *md);
/*
* Test if the device is scheduled for deferred remove.
*/
int dm_test_deferred_remove_flag(struct mapped_device *md);
/*
* Try to remove devices marked for deferred removal.
*/
void dm_deferred_remove(void);
/*
* The device-mapper can be driven through one of two interfaces;
* ioctl or filesystem, depending which patch you have applied.
*/
int dm_interface_init(void);
void dm_interface_exit(void);
/*
* sysfs interface
*/
int dm_sysfs_init(struct mapped_device *md);
void dm_sysfs_exit(struct mapped_device *md);
struct kobject *dm_kobject(struct mapped_device *md);
struct mapped_device *dm_get_from_kobject(struct kobject *kobj);
/*
* The kobject helper
*/
void dm_kobject_release(struct kobject *kobj);
/*
* Targets for linear and striped mappings
*/
int dm_linear_init(void);
void dm_linear_exit(void);
int dm_stripe_init(void);
void dm_stripe_exit(void);
/*
* mapped_device operations
*/
void dm_destroy(struct mapped_device *md);
void dm_destroy_immediate(struct mapped_device *md);
int dm_open_count(struct mapped_device *md);
int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred);
int dm_cancel_deferred_remove(struct mapped_device *md);
int dm_request_based(struct mapped_device *md);
int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
struct dm_dev **result);
void dm_put_table_device(struct mapped_device *md, struct dm_dev *d);
int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
unsigned int cookie, bool need_resize_uevent);
void dm_internal_suspend(struct mapped_device *md);
void dm_internal_resume(struct mapped_device *md);
int dm_io_init(void);
void dm_io_exit(void);
int dm_kcopyd_init(void);
void dm_kcopyd_exit(void);
/*
* Mempool operations
*/
void dm_free_md_mempools(struct dm_md_mempools *pools);
/*
* Various helpers
*/
unsigned int dm_get_reserved_bio_based_ios(void);
#define DM_HASH_LOCKS_MAX 64
static inline unsigned int dm_num_hash_locks(void)
{
unsigned int num_locks = roundup_pow_of_two(num_online_cpus()) << 1;
return min_t(unsigned int, num_locks, DM_HASH_LOCKS_MAX);
}
#define DM_HASH_LOCKS_MULT 4294967291ULL
#define DM_HASH_LOCKS_SHIFT 6
static inline unsigned int dm_hash_locks_index(sector_t block,
unsigned int num_locks)
{
sector_t h1 = (block * DM_HASH_LOCKS_MULT) >> DM_HASH_LOCKS_SHIFT;
sector_t h2 = h1 >> DM_HASH_LOCKS_SHIFT;
return (h1 ^ h2) & (num_locks - 1);
}
#endif
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