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dm: add reserved_rq_based_ios module parameter 

Allow user to change the number of IOs that are reserved by
request-based DM's mempools by writing to this file:
/sys/module/dm_mod/parameters/reserved_rq_based_ios

The default value is RESERVED_REQUEST_BASED_IOS (256).  The maximum
allowed value is RESERVED_MAX_IOS (1024).

Export dm_get_reserved_rq_based_ios() for use by DM targets and core
code.  Switch to sizing dm-mpath's mempool using DM core's configurable
'reserved_rq_based_ios'.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Frank Mayhar <fmayhar@google.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
This commit is contained in:
Mike Snitzer 2013-09-12 18:06:12 -04:00
parent 6cfa58573f
commit f47908269f
3 changed files with 42 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/md/dm-mpath.c
View File

@ -7,6 +7,7 @@
#include <linux/device-mapper.h>
#include "dm.h"
#include "dm-path-selector.h"
#include "dm-uevent.h"
@ -116,8 +117,6 @@ struct dm_mpath_io {
typedef int (*action_fn) (struct pgpath *pgpath);
#define MIN_IOS 256 /* Mempool size */
static struct kmem_cache *_mpio_cache;
static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
@ -190,6 +189,7 @@ static void free_priority_group(struct priority_group *pg,
static struct multipath *alloc_multipath(struct dm_target *ti)
{
struct multipath *m;
unsigned min_ios = dm_get_reserved_rq_based_ios();
m = kzalloc(sizeof(*m), GFP_KERNEL);
if (m) {
@ -202,7 +202,7 @@ static struct multipath *alloc_multipath(struct dm_target *ti)
INIT_WORK(&m->trigger_event, trigger_event);
init_waitqueue_head(&m->pg_init_wait);
mutex_init(&m->work_mutex);
m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
if (!m->mpio_pool) {
kfree(m);
return NULL;

38
drivers/md/dm.c
View File

@ -213,9 +213,41 @@ struct dm_md_mempools {
#define RESERVED_BIO_BASED_IOS 16
#define RESERVED_REQUEST_BASED_IOS 256
#define RESERVED_MAX_IOS 1024
static struct kmem_cache *_io_cache;
static struct kmem_cache *_rq_tio_cache;
/*
* Request-based DM's mempools' reserved IOs set by the user.
*/
static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
static unsigned __dm_get_reserved_ios(unsigned *reserved_ios,
unsigned def, unsigned max)
{
unsigned ios = ACCESS_ONCE(*reserved_ios);
unsigned modified_ios = 0;
if (!ios)
modified_ios = def;
else if (ios > max)
modified_ios = max;
if (modified_ios) {
(void)cmpxchg(reserved_ios, ios, modified_ios);
ios = modified_ios;
}
return ios;
}
unsigned dm_get_reserved_rq_based_ios(void)
{
return __dm_get_reserved_ios(&reserved_rq_based_ios,
RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS);
}
EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
static int __init local_init(void)
{
int r = -ENOMEM;
@ -2878,7 +2910,7 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
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;
pool_size = RESERVED_REQUEST_BASED_IOS;
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);
@ -2936,6 +2968,10 @@ module_exit(dm_exit);
module_param(major, uint, 0);
MODULE_PARM_DESC(major, "The major number of the device mapper");
module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
MODULE_DESCRIPTION(DM_NAME " driver");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");

2
drivers/md/dm.h
View File

@ -184,6 +184,8 @@ void dm_free_md_mempools(struct dm_md_mempools *pools);
/*
* Helpers that are used by DM core
*/
unsigned dm_get_reserved_rq_based_ios(void);
static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
{
return !maxlen || strlen(result) + 1 >= maxlen;