s390/scm_block: use mempool to manage aidaw requests

We currently use one preallocated page per HW request to store
aidaws. With this patch we use mempool to allocate an aidaw page
whenever we need it.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 38 insertions, 7 deletions

diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index 56046ab39629..5b2abadea094 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -10,6 +10,7 @@
 
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
+#include <linux/mempool.h>
 #include <linux/module.h>
 #include <linux/blkdev.h>
 #include <linux/genhd.h>
@@ -20,6 +21,7 @@
 
 debug_info_t *scm_debug;
 static int scm_major;
+static mempool_t *aidaw_pool;
 static DEFINE_SPINLOCK(list_lock);
 static LIST_HEAD(inactive_requests);
 static unsigned int nr_requests = 64;
@@ -36,7 +38,6 @@ static void __scm_free_rq(struct scm_request *scmrq)
 	struct aob_rq_header *aobrq = to_aobrq(scmrq);
 
 	free_page((unsigned long) scmrq->aob);
-	free_page((unsigned long) scmrq->aidaw);
 	__scm_free_rq_cluster(scmrq);
 	kfree(aobrq);
 }
@@ -53,6 +54,8 @@ static void scm_free_rqs(void)
 		__scm_free_rq(scmrq);
 	}
 	spin_unlock_irq(&list_lock);
+
+	mempool_destroy(aidaw_pool);
 }
 
 static int __scm_alloc_rq(void)
@@ -65,9 +68,8 @@ static int __scm_alloc_rq(void)
 		return -ENOMEM;
 
 	scmrq = (void *) aobrq->data;
-	scmrq->aidaw = (void *) get_zeroed_page(GFP_DMA);
 	scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
-	if (!scmrq->aob || !scmrq->aidaw) {
+	if (!scmrq->aob) {
 		__scm_free_rq(scmrq);
 		return -ENOMEM;
 	}
@@ -89,6 +91,10 @@ static int scm_alloc_rqs(unsigned int nrqs)
 {
 	int ret = 0;
 
+	aidaw_pool = mempool_create_page_pool(max(nrqs/8, 1U), 0);
+	if (!aidaw_pool)
+		return -ENOMEM;
+
 	while (nrqs-- && !ret)
 		ret = __scm_alloc_rq();
 
@@ -111,8 +117,13 @@ out:
 
 static void scm_request_done(struct scm_request *scmrq)
 {
+	struct msb *msb = &scmrq->aob->msb[0];
+	u64 aidaw = msb->data_addr;
 	unsigned long flags;
 
+	if ((msb->flags & MSB_FLAG_IDA) && aidaw)
+		mempool_free(virt_to_page(aidaw), aidaw_pool);
+
 	spin_lock_irqsave(&list_lock, flags);
 	list_add(&scmrq->list, &inactive_requests);
 	spin_unlock_irqrestore(&list_lock, flags);
@@ -123,15 +134,26 @@ static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
 	return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
 }
 
-static void scm_request_prepare(struct scm_request *scmrq)
+struct aidaw *scm_aidaw_alloc(void)
+{
+	struct page *page = mempool_alloc(aidaw_pool, GFP_ATOMIC);
+
+	return page ? page_address(page) : NULL;
+}
+
+static int scm_request_prepare(struct scm_request *scmrq)
 {
 	struct scm_blk_dev *bdev = scmrq->bdev;
 	struct scm_device *scmdev = bdev->gendisk->private_data;
-	struct aidaw *aidaw = scmrq->aidaw;
+	struct aidaw *aidaw = scm_aidaw_alloc();
 	struct msb *msb = &scmrq->aob->msb[0];
 	struct req_iterator iter;
 	struct bio_vec bv;
 
+	if (!aidaw)
+		return -ENOMEM;
+
+	memset(aidaw, 0, PAGE_SIZE);
 	msb->bs = MSB_BS_4K;
 	scmrq->aob->request.msb_count = 1;
 	msb->scm_addr = scmdev->address +
@@ -147,6 +169,8 @@ static void scm_request_prepare(struct scm_request *scmrq)
 		aidaw->data_addr = (u64) page_address(bv.bv_page);
 		aidaw++;
 	}
+
+	return 0;
 }
 
 static inline void scm_request_init(struct scm_blk_dev *bdev,
@@ -157,7 +181,6 @@ static inline void scm_request_init(struct scm_blk_dev *bdev,
 	struct aob *aob = scmrq->aob;
 
 	memset(aob, 0, sizeof(*aob));
-	memset(scmrq->aidaw, 0, PAGE_SIZE);
 	aobrq->scmdev = bdev->scmdev;
 	aob->request.cmd_code = ARQB_CMD_MOVE;
 	aob->request.data = (u64) aobrq;
@@ -236,7 +259,15 @@ static void scm_blk_request(struct request_queue *rq)
 			scm_initiate_cluster_request(scmrq);
 			return;
 		}
-		scm_request_prepare(scmrq);
+
+		if (scm_request_prepare(scmrq)) {
+			SCM_LOG(5, "no aidaw");
+			scm_release_cluster(scmrq);
+			scm_request_done(scmrq);
+			scm_ensure_queue_restart(bdev);
+			return;
+		}
+
 		atomic_inc(&bdev->queued_reqs);
 		blk_start_request(req);