mirror of
https://github.com/torvalds/linux.git
synced 2025-11-04 02:30:34 +02:00
8ca817c43e
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
107 lines
2.9 KiB
C
107 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* Copyright (C) 2003 Sistina Software.
|
|
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* Module Author: Heinz Mauelshagen
|
|
*
|
|
* This file is released under the GPL.
|
|
*
|
|
* Path-Selector registration.
|
|
*/
|
|
|
|
#ifndef DM_PATH_SELECTOR_H
|
|
#define DM_PATH_SELECTOR_H
|
|
|
|
#include <linux/device-mapper.h>
|
|
|
|
#include "dm-mpath.h"
|
|
|
|
/*
|
|
* We provide an abstraction for the code that chooses which path
|
|
* to send some io down.
|
|
*/
|
|
struct path_selector_type;
|
|
struct path_selector {
|
|
struct path_selector_type *type;
|
|
void *context;
|
|
};
|
|
|
|
/*
|
|
* If a path selector uses this flag, a high resolution timer is used
|
|
* (via ktime_get_ns) to account for IO start time in BIO-based mpath.
|
|
* This improves performance of some path selectors (i.e. HST), in
|
|
* exchange for slightly higher overhead when submitting the BIO.
|
|
* The extra cost is usually offset by improved path selection for
|
|
* some benchmarks.
|
|
*
|
|
* This has no effect for request-based mpath, since it already uses a
|
|
* higher precision timer by default.
|
|
*/
|
|
#define DM_PS_USE_HR_TIMER 0x00000001
|
|
#define dm_ps_use_hr_timer(type) ((type)->features & DM_PS_USE_HR_TIMER)
|
|
|
|
/* Information about a path selector type */
|
|
struct path_selector_type {
|
|
char *name;
|
|
struct module *module;
|
|
|
|
unsigned int features;
|
|
unsigned int table_args;
|
|
unsigned int info_args;
|
|
|
|
/*
|
|
* Constructs a path selector object, takes custom arguments
|
|
*/
|
|
int (*create)(struct path_selector *ps, unsigned int argc, char **argv);
|
|
void (*destroy)(struct path_selector *ps);
|
|
|
|
/*
|
|
* Add an opaque path object, along with some selector specific
|
|
* path args (eg, path priority).
|
|
*/
|
|
int (*add_path)(struct path_selector *ps, struct dm_path *path,
|
|
int argc, char **argv, char **error);
|
|
|
|
/*
|
|
* Chooses a path for this io, if no paths are available then
|
|
* NULL will be returned.
|
|
*/
|
|
struct dm_path *(*select_path)(struct path_selector *ps, size_t nr_bytes);
|
|
|
|
/*
|
|
* Notify the selector that a path has failed.
|
|
*/
|
|
void (*fail_path)(struct path_selector *ps, struct dm_path *p);
|
|
|
|
/*
|
|
* Ask selector to reinstate a path.
|
|
*/
|
|
int (*reinstate_path)(struct path_selector *ps, struct dm_path *p);
|
|
|
|
/*
|
|
* Table content based on parameters added in ps_add_path_fn
|
|
* or path selector status
|
|
*/
|
|
int (*status)(struct path_selector *ps, struct dm_path *path,
|
|
status_type_t type, char *result, unsigned int maxlen);
|
|
|
|
int (*start_io)(struct path_selector *ps, struct dm_path *path,
|
|
size_t nr_bytes);
|
|
int (*end_io)(struct path_selector *ps, struct dm_path *path,
|
|
size_t nr_bytes, u64 start_time);
|
|
};
|
|
|
|
/* Register a path selector */
|
|
int dm_register_path_selector(struct path_selector_type *type);
|
|
|
|
/* Unregister a path selector */
|
|
int dm_unregister_path_selector(struct path_selector_type *type);
|
|
|
|
/* Returns a registered path selector type */
|
|
struct path_selector_type *dm_get_path_selector(const char *name);
|
|
|
|
/* Releases a path selector */
|
|
void dm_put_path_selector(struct path_selector_type *pst);
|
|
|
|
#endif
|