[PATCH 4/7] dm io: use dm_get_reserved_bio_based_ios to size reserves

[Mike Snitzer <snitzer@redhat.com>]

Switch dm-io over to sizing its mempool and bioset using DM core's
configurable 'reserved_bio_based_ios'.

Export dm_get_reserved_bio_based_ios() for use by DM targets and core
code.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/dm-io.c |  7 +++----
 drivers/md/dm.c    | 12 ++++++++++++
 drivers/md/dm.h    |  2 ++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index ea49834..2a20986 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -19,8 +19,6 @@
 #define DM_MSG_PREFIX "io"
 
 #define DM_IO_MAX_REGIONS	BITS_PER_LONG
-#define MIN_IOS		16
-#define MIN_BIOS	16
 
 struct dm_io_client {
 	mempool_t *pool;
@@ -50,16 +48,17 @@ static struct kmem_cache *_dm_io_cache;
 struct dm_io_client *dm_io_client_create(void)
 {
 	struct dm_io_client *client;
+	unsigned min_ios = dm_get_reserved_bio_based_ios();
 
 	client = kmalloc(sizeof(*client), GFP_KERNEL);
 	if (!client)
 		return ERR_PTR(-ENOMEM);
 
-	client->pool = mempool_create_slab_pool(MIN_IOS, _dm_io_cache);
+	client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache);
 	if (!client->pool)
 		goto bad;
 
-	client->bios = bioset_create(MIN_BIOS, 0);
+	client->bios = bioset_create(min_ios, 0);
 	if (!client->bios)
 		goto bad;
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b44ae19..3f96c86 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -259,6 +259,18 @@ static void __reserved_bio_based_ios_refresh(void)
 	}
 }
 
+unsigned dm_get_reserved_bio_based_ios(void)
+{
+	unsigned ios;
+
+	mutex_lock(&dm_mempools_lock);
+	ios = reserved_bio_based_ios_latch;
+	mutex_unlock(&dm_mempools_lock);
+
+	return (ios ? : RESERVED_BIO_BASED_IOS);
+}
+EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios);
+
 static void __reserved_request_based_ios_refresh(void)
 {
 	BUG_ON(!mutex_is_locked(&dm_mempools_lock));
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 5e604cc..e1982eb 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -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_bio_based_ios(void);
+
 static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
 {
 	return !maxlen || strlen(result) + 1 >= maxlen;
-- 
1.8.1.4