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>
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index e08be94..de570a5 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -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 @@
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 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 @@
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;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f2e5a50..1e85f1d 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -213,9 +213,41 @@
#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 @@
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_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");
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 5e604cc..1539650 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -184,6 +184,8 @@
/*
* 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;
