e5863d9ad7
For blk-mq request-based DM the responsibility of allocating a cloned request is transfered from DM core to the target type. Doing so enables the cloned request to be allocated from the appropriate blk-mq request_queue's pool (only the DM target, e.g. multipath, can know which block device to send a given cloned request to). Care was taken to preserve compatibility with old-style block request completion that requires request-based DM _not_ acquire the clone request's queue lock in the completion path. As such, there are now 2 different request-based DM target_type interfaces: 1) the original .map_rq() interface will continue to be used for non-blk-mq devices -- the preallocated clone request is passed in from DM core. 2) a new .clone_and_map_rq() and .release_clone_rq() will be used for blk-mq devices -- blk_get_request() and blk_put_request() are used respectively from these hooks. dm_table_set_type() was updated to detect if the request-based target is being stacked on blk-mq devices, if so DM_TYPE_MQ_REQUEST_BASED is set. DM core disallows switching the DM table's type after it is set. This means that there is no mixing of non-blk-mq and blk-mq devices within the same request-based DM table. [This patch was started by Keith and later heavily modified by Mike] Tested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
174 lines
3 KiB
C
174 lines
3 KiB
C
/*
|
|
* Copyright (C) 2001 Sistina Software (UK) Limited
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#include "dm.h"
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/kmod.h>
|
|
#include <linux/bio.h>
|
|
|
|
#define DM_MSG_PREFIX "target"
|
|
|
|
static LIST_HEAD(_targets);
|
|
static DECLARE_RWSEM(_lock);
|
|
|
|
#define DM_MOD_NAME_SIZE 32
|
|
|
|
static inline struct target_type *__find_target_type(const char *name)
|
|
{
|
|
struct target_type *tt;
|
|
|
|
list_for_each_entry(tt, &_targets, list)
|
|
if (!strcmp(name, tt->name))
|
|
return tt;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct target_type *get_target_type(const char *name)
|
|
{
|
|
struct target_type *tt;
|
|
|
|
down_read(&_lock);
|
|
|
|
tt = __find_target_type(name);
|
|
if (tt && !try_module_get(tt->module))
|
|
tt = NULL;
|
|
|
|
up_read(&_lock);
|
|
return tt;
|
|
}
|
|
|
|
static void load_module(const char *name)
|
|
{
|
|
request_module("dm-%s", name);
|
|
}
|
|
|
|
struct target_type *dm_get_target_type(const char *name)
|
|
{
|
|
struct target_type *tt = get_target_type(name);
|
|
|
|
if (!tt) {
|
|
load_module(name);
|
|
tt = get_target_type(name);
|
|
}
|
|
|
|
return tt;
|
|
}
|
|
|
|
void dm_put_target_type(struct target_type *tt)
|
|
{
|
|
down_read(&_lock);
|
|
module_put(tt->module);
|
|
up_read(&_lock);
|
|
}
|
|
|
|
int dm_target_iterate(void (*iter_func)(struct target_type *tt,
|
|
void *param), void *param)
|
|
{
|
|
struct target_type *tt;
|
|
|
|
down_read(&_lock);
|
|
list_for_each_entry(tt, &_targets, list)
|
|
iter_func(tt, param);
|
|
up_read(&_lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int dm_register_target(struct target_type *tt)
|
|
{
|
|
int rv = 0;
|
|
|
|
down_write(&_lock);
|
|
if (__find_target_type(tt->name))
|
|
rv = -EEXIST;
|
|
else
|
|
list_add(&tt->list, &_targets);
|
|
|
|
up_write(&_lock);
|
|
return rv;
|
|
}
|
|
|
|
void dm_unregister_target(struct target_type *tt)
|
|
{
|
|
down_write(&_lock);
|
|
if (!__find_target_type(tt->name)) {
|
|
DMCRIT("Unregistering unrecognised target: %s", tt->name);
|
|
BUG();
|
|
}
|
|
|
|
list_del(&tt->list);
|
|
|
|
up_write(&_lock);
|
|
}
|
|
|
|
/*
|
|
* io-err: always fails an io, useful for bringing
|
|
* up LVs that have holes in them.
|
|
*/
|
|
static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args)
|
|
{
|
|
/*
|
|
* Return error for discards instead of -EOPNOTSUPP
|
|
*/
|
|
tt->num_discard_bios = 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void io_err_dtr(struct dm_target *tt)
|
|
{
|
|
/* empty */
|
|
}
|
|
|
|
static int io_err_map(struct dm_target *tt, struct bio *bio)
|
|
{
|
|
return -EIO;
|
|
}
|
|
|
|
static int io_err_map_rq(struct dm_target *ti, struct request *clone,
|
|
union map_info *map_context)
|
|
{
|
|
return -EIO;
|
|
}
|
|
|
|
static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq,
|
|
union map_info *map_context,
|
|
struct request **clone)
|
|
{
|
|
return -EIO;
|
|
}
|
|
|
|
static void io_err_release_clone_rq(struct request *clone)
|
|
{
|
|
}
|
|
|
|
static struct target_type error_target = {
|
|
.name = "error",
|
|
.version = {1, 3, 0},
|
|
.ctr = io_err_ctr,
|
|
.dtr = io_err_dtr,
|
|
.map = io_err_map,
|
|
.map_rq = io_err_map_rq,
|
|
.clone_and_map_rq = io_err_clone_and_map_rq,
|
|
.release_clone_rq = io_err_release_clone_rq,
|
|
};
|
|
|
|
int __init dm_target_init(void)
|
|
{
|
|
return dm_register_target(&error_target);
|
|
}
|
|
|
|
void dm_target_exit(void)
|
|
{
|
|
dm_unregister_target(&error_target);
|
|
}
|
|
|
|
EXPORT_SYMBOL(dm_register_target);
|
|
EXPORT_SYMBOL(dm_unregister_target);
|