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dm: allocate requests in target when stacking on blk-mq devices

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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>
This commit is contained in:
Mike Snitzer 2014-12-17 21:08:12 -05:00
parent 466d89a6bc
commit e5863d9ad7
7 changed files with 185 additions and 48 deletions
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51
drivers/md/dm-mpath.c
View File

@ -11,6 +11,7 @@
#include "dm-path-selector.h"
#include "dm-uevent.h"
#include <linux/blkdev.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/mempool.h>
@ -378,12 +379,13 @@ static int __must_push_back(struct multipath *m)
/*
* Map cloned requests
*/
static int multipath_map(struct dm_target *ti, struct request *clone,
union map_info *map_context)
static int __multipath_map(struct dm_target *ti, struct request *clone,
union map_info *map_context,
struct request *rq, struct request **__clone)
{
struct multipath *m = (struct multipath *) ti->private;
int r = DM_MAPIO_REQUEUE;
size_t nr_bytes = blk_rq_bytes(clone);
size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
struct pgpath *pgpath;
struct block_device *bdev;
struct dm_mpath_io *mpio;
@ -416,12 +418,25 @@ static int multipath_map(struct dm_target *ti, struct request *clone,
bdev = pgpath->path.dev->bdev;
clone->q = bdev_get_queue(bdev);
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
spin_unlock_irq(&m->lock);
if (clone) {
/* Old request-based interface: allocated clone is passed in */
clone->q = bdev_get_queue(bdev);
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
} else {
/* blk-mq request-based interface */
*__clone = blk_get_request(bdev_get_queue(bdev),
rq_data_dir(rq), GFP_KERNEL);
if (IS_ERR(*__clone))
/* ENOMEM, requeue */
return r;
(*__clone)->bio = (*__clone)->biotail = NULL;
(*__clone)->rq_disk = bdev->bd_disk;
(*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
}
if (pgpath->pg->ps.type->start_io)
pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
&pgpath->path,
@ -434,6 +449,24 @@ static int multipath_map(struct dm_target *ti, struct request *clone,
return r;
}
static int multipath_map(struct dm_target *ti, struct request *clone,
union map_info *map_context)
{
return __multipath_map(ti, clone, map_context, NULL, NULL);
}
static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
union map_info *map_context,
struct request **clone)
{
return __multipath_map(ti, NULL, map_context, rq, clone);
}
static void multipath_release_clone(struct request *clone)
{
blk_put_request(clone);
}
/*
* If we run out of usable paths, should we queue I/O or error it?
*/
@ -1670,11 +1703,13 @@ static int multipath_busy(struct dm_target *ti)
*---------------------------------------------------------------*/
static struct target_type multipath_target = {
.name = "multipath",
.version = {1, 7, 0},
.version = {1, 8, 0},
.module = THIS_MODULE,
.ctr = multipath_ctr,
.dtr = multipath_dtr,
.map_rq = multipath_map,
.clone_and_map_rq = multipath_clone_and_map,
.release_clone_rq = multipath_release_clone,
.rq_end_io = multipath_end_io,
.presuspend = multipath_presuspend,
.postsuspend = multipath_postsuspend,

34
drivers/md/dm-table.c
View File

@ -827,6 +827,7 @@ static int dm_table_set_type(struct dm_table *t)
{
unsigned i;
unsigned bio_based = 0, request_based = 0, hybrid = 0;
bool use_blk_mq = false;
struct dm_target *tgt;
struct dm_dev_internal *dd;
struct list_head *devices;
@ -872,11 +873,26 @@ static int dm_table_set_type(struct dm_table *t)
/* Non-request-stackable devices can't be used for request-based dm */
devices = dm_table_get_devices(t);
list_for_each_entry(dd, devices, list) {
if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev->bdev))) {
DMWARN("table load rejected: including"
" non-request-stackable devices");
struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
if (!blk_queue_stackable(q)) {
DMERR("table load rejected: including"
" non-request-stackable devices");
return -EINVAL;
}
if (q->mq_ops)
use_blk_mq = true;
}
if (use_blk_mq) {
/* verify _all_ devices in the table are blk-mq devices */
list_for_each_entry(dd, devices, list)
if (!bdev_get_queue(dd->dm_dev->bdev)->mq_ops) {
DMERR("table load rejected: not all devices"
" are blk-mq request-stackable");
return -EINVAL;
}
}
/*
@ -890,7 +906,7 @@ static int dm_table_set_type(struct dm_table *t)
return -EINVAL;
}
t->type = DM_TYPE_REQUEST_BASED;
t->type = !use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED;
return 0;
}
@ -907,7 +923,15 @@ struct target_type *dm_table_get_immutable_target_type(struct dm_table *t)
bool dm_table_request_based(struct dm_table *t)
{
return dm_table_get_type(t) == DM_TYPE_REQUEST_BASED;
unsigned table_type = dm_table_get_type(t);
return (table_type == DM_TYPE_REQUEST_BASED ||
table_type == DM_TYPE_MQ_REQUEST_BASED);
}
bool dm_table_mq_request_based(struct dm_table *t)
{
return dm_table_get_type(t) == DM_TYPE_MQ_REQUEST_BASED;
}
static int dm_table_alloc_md_mempools(struct dm_table *t)

15
drivers/md/dm-target.c
View File

@ -137,13 +137,26 @@ static int io_err_map_rq(struct dm_target *ti, struct request *clone,
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, 2, 0},
.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)

114
drivers/md/dm.c
View File

@ -1044,7 +1044,10 @@ static void free_rq_clone(struct request *clone)
struct dm_rq_target_io *tio = clone->end_io_data;
blk_rq_unprep_clone(clone);
free_clone_request(tio->md, clone);
if (clone->q && clone->q->mq_ops)
tio->ti->type->release_clone_rq(clone);
else
free_clone_request(tio->md, clone);
free_rq_tio(tio);
}
@ -1086,7 +1089,8 @@ static void dm_unprep_request(struct request *rq)
rq->special = NULL;
rq->cmd_flags &= ~REQ_DONTPREP;
free_rq_clone(clone);
if (clone)
free_rq_clone(clone);
}
/*
@ -1185,6 +1189,13 @@ static void dm_softirq_done(struct request *rq)
struct dm_rq_target_io *tio = rq->special;
struct request *clone = tio->clone;
if (!clone) {
blk_end_request_all(rq, tio->error);
rq_completed(tio->md, rq_data_dir(rq), false);
free_rq_tio(tio);
return;
}
if (rq->cmd_flags & REQ_FAILED)
mapped = false;
@ -1207,7 +1218,7 @@ static void dm_complete_request(struct request *rq, int error)
* Complete the not-mapped clone and the original request with the error status
* through softirq context.
* Target's rq_end_io() function isn't called.
* This may be used when the target's map_rq() function fails.
* This may be used when the target's map_rq() or clone_and_map_rq() functions fail.
*/
static void dm_kill_unmapped_request(struct request *rq, int error)
{
@ -1222,13 +1233,15 @@ static void end_clone_request(struct request *clone, int error)
{
struct dm_rq_target_io *tio = clone->end_io_data;
/*
* For just cleaning up the information of the queue in which
* the clone was dispatched.
* The clone is *NOT* freed actually here because it is alloced from
* dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags.
*/
__blk_put_request(clone->q, clone);
if (!clone->q->mq_ops) {
/*
* For just cleaning up the information of the queue in which
* the clone was dispatched.
* The clone is *NOT* freed actually here because it is alloced
* from dm own mempool (REQ_ALLOCED isn't set).
*/
__blk_put_request(clone->q, clone);
}
/*
* Actual request completion is done in a softirq context which doesn't
@ -1789,6 +1802,8 @@ static struct dm_rq_target_io *prep_tio(struct request *rq,
struct mapped_device *md, gfp_t gfp_mask)
{
struct dm_rq_target_io *tio;
int srcu_idx;
struct dm_table *table;
tio = alloc_rq_tio(md, gfp_mask);
if (!tio)
@ -1802,10 +1817,15 @@ static struct dm_rq_target_io *prep_tio(struct request *rq,
memset(&tio->info, 0, sizeof(tio->info));
init_kthread_work(&tio->work, map_tio_request);
if (!clone_rq(rq, md, tio, gfp_mask)) {
free_rq_tio(tio);
return NULL;
table = dm_get_live_table(md, &srcu_idx);
if (!dm_table_mq_request_based(table)) {
if (!clone_rq(rq, md, tio, gfp_mask)) {
dm_put_live_table(md, srcu_idx);
free_rq_tio(tio);
return NULL;
}
}
dm_put_live_table(md, srcu_idx);
return tio;
}
@ -1835,17 +1855,36 @@ static int dm_prep_fn(struct request_queue *q, struct request *rq)
/*
* Returns:
* 0 : the request has been processed (not requeued)
* !0 : the request has been requeued
* 0 : the request has been processed
* DM_MAPIO_REQUEUE : the original request needs to be requeued
* < 0 : the request was completed due to failure
*/
static int map_request(struct dm_target *ti, struct request *rq,
struct mapped_device *md)
{
int r, requeued = 0;
int r;
struct dm_rq_target_io *tio = rq->special;
struct request *clone = tio->clone;
struct request *clone = NULL;
if (tio->clone) {
clone = tio->clone;
r = ti->type->map_rq(ti, clone, &tio->info);
} else {
r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
if (r < 0) {
/* The target wants to complete the I/O */
dm_kill_unmapped_request(rq, r);
return r;
}
if (IS_ERR(clone))
return DM_MAPIO_REQUEUE;
if (setup_clone(clone, rq, tio, GFP_KERNEL)) {
/* -ENOMEM */
ti->type->release_clone_rq(clone);
return DM_MAPIO_REQUEUE;
}
}
r = ti->type->map_rq(ti, clone, &tio->info);
switch (r) {
case DM_MAPIO_SUBMITTED:
/* The target has taken the I/O to submit by itself later */
@ -1859,7 +1898,6 @@ static int map_request(struct dm_target *ti, struct request *rq,
case DM_MAPIO_REQUEUE:
/* The target wants to requeue the I/O */
dm_requeue_unmapped_request(clone);
requeued = 1;
break;
default:
if (r > 0) {
@ -1869,17 +1907,20 @@ static int map_request(struct dm_target *ti, struct request *rq,
/* The target wants to complete the I/O */
dm_kill_unmapped_request(rq, r);
break;
return r;
}
return requeued;
return 0;
}
static void map_tio_request(struct kthread_work *work)
{
struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
struct request *rq = tio->orig;
struct mapped_device *md = tio->md;
map_request(tio->ti, tio->orig, tio->md);
if (map_request(tio->ti, rq, md) == DM_MAPIO_REQUEUE)
dm_requeue_unmapped_original_request(md, rq);
}
static void dm_start_request(struct mapped_device *md, struct request *orig)
@ -2459,6 +2500,14 @@ unsigned dm_get_md_type(struct mapped_device *md)
return md->type;
}
static bool dm_md_type_request_based(struct mapped_device *md)
{
unsigned table_type = dm_get_md_type(md);
return (table_type == DM_TYPE_REQUEST_BASED ||
table_type == DM_TYPE_MQ_REQUEST_BASED);
}
struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
{
return md->immutable_target_type;
@ -2511,8 +2560,7 @@ static int dm_init_request_based_queue(struct mapped_device *md)
*/
int dm_setup_md_queue(struct mapped_device *md)
{
if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) &&
!dm_init_request_based_queue(md)) {
if (dm_md_type_request_based(md) && !dm_init_request_based_queue(md)) {
DMWARN("Cannot initialize queue for request-based mapped device");
return -EINVAL;
}
@ -3184,27 +3232,35 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
{
struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
struct kmem_cache *cachep;
unsigned int pool_size;
unsigned int pool_size = 0;
unsigned int front_pad;
if (!pools)
return NULL;
if (type == DM_TYPE_BIO_BASED) {
switch (type) {
case DM_TYPE_BIO_BASED:
cachep = _io_cache;
pool_size = dm_get_reserved_bio_based_ios();
front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
} else if (type == DM_TYPE_REQUEST_BASED) {
cachep = _rq_tio_cache;
break;
case DM_TYPE_REQUEST_BASED:
pool_size = dm_get_reserved_rq_based_ios();
pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);
if (!pools->rq_pool)
goto out;
/* fall through to setup remaining rq-based pools */
case DM_TYPE_MQ_REQUEST_BASED:
cachep = _rq_tio_cache;
if (!pool_size)
pool_size = dm_get_reserved_rq_based_ios();
front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
/* per_bio_data_size is not used. See __bind_mempools(). */
WARN_ON(per_bio_data_size != 0);
} else
break;
default:
goto out;
}
pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
if (!pools->io_pool)

8
drivers/md/dm.h
View File

@ -34,9 +34,10 @@
/*
* Type of table and mapped_device's mempool
*/
#define DM_TYPE_NONE 0
#define DM_TYPE_BIO_BASED 1
#define DM_TYPE_REQUEST_BASED 2
#define DM_TYPE_NONE 0
#define DM_TYPE_BIO_BASED 1
#define DM_TYPE_REQUEST_BASED 2
#define DM_TYPE_MQ_REQUEST_BASED 3
/*
* List of devices that a metadevice uses and should open/close.
@ -73,6 +74,7 @@ int dm_table_any_busy_target(struct dm_table *t);
unsigned dm_table_get_type(struct dm_table *t);
struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
bool dm_table_request_based(struct dm_table *t);
bool dm_table_mq_request_based(struct dm_table *t);
void dm_table_free_md_mempools(struct dm_table *t);
struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);

7
include/linux/device-mapper.h
View File

@ -48,6 +48,11 @@ typedef void (*dm_dtr_fn) (struct dm_target *ti);
typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
union map_info *map_context);
typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
struct request *rq,
union map_info *map_context,
struct request **clone);
typedef void (*dm_release_clone_request_fn) (struct request *clone);
/*
* Returns:
@ -143,6 +148,8 @@ struct target_type {
dm_dtr_fn dtr;
dm_map_fn map;
dm_map_request_fn map_rq;
dm_clone_and_map_request_fn clone_and_map_rq;
dm_release_clone_request_fn release_clone_rq;
dm_endio_fn end_io;
dm_request_endio_fn rq_end_io;
dm_presuspend_fn presuspend;

4
include/uapi/linux/dm-ioctl.h
View File

@ -267,9 +267,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
#define DM_VERSION_MINOR 29
#define DM_VERSION_MINOR 30
#define DM_VERSION_PATCHLEVEL 0
#define DM_VERSION_EXTRA "-ioctl (2014-10-28)"
#define DM_VERSION_EXTRA "-ioctl (2014-12-22)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */