s390/scm_block: force cluster writes
Force writes to Storage Class Memory (SCM) to be in done in clusters.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/Kconfig b/drivers/s390/block/Kconfig
index 18178b6..4a3b623 100644
--- a/drivers/s390/block/Kconfig
+++ b/drivers/s390/block/Kconfig
@@ -81,3 +81,10 @@
To compile this driver as a module, choose M here: the
module will be called scm_block.
+
+config SCM_BLOCK_CLUSTER_WRITE
+ def_bool y
+ prompt "SCM force cluster writes"
+ depends on SCM_BLOCK
+ help
+ Force writes to Storage Class Memory (SCM) to be in done in clusters.
diff --git a/drivers/s390/block/Makefile b/drivers/s390/block/Makefile
index b64e2b3..c2f4e67 100644
--- a/drivers/s390/block/Makefile
+++ b/drivers/s390/block/Makefile
@@ -19,4 +19,7 @@
obj-$(CONFIG_DCSSBLK) += dcssblk.o
scm_block-objs := scm_drv.o scm_blk.o
+ifdef CONFIG_SCM_BLOCK_CLUSTER_WRITE
+scm_block-objs += scm_blk_cluster.o
+endif
obj-$(CONFIG_SCM_BLOCK) += scm_block.o
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index 634ad58..9978ad4 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -37,6 +37,7 @@
free_page((unsigned long) scmrq->aob);
free_page((unsigned long) scmrq->aidaw);
+ __scm_free_rq_cluster(scmrq);
kfree(aobrq);
}
@@ -70,6 +71,12 @@
__scm_free_rq(scmrq);
return -ENOMEM;
}
+
+ if (__scm_alloc_rq_cluster(scmrq)) {
+ __scm_free_rq(scmrq);
+ return -ENOMEM;
+ }
+
INIT_LIST_HEAD(&scmrq->list);
spin_lock_irq(&list_lock);
list_add(&scmrq->list, &inactive_requests);
@@ -170,6 +177,7 @@
scmrq->bdev = bdev;
scmrq->retries = 4;
scmrq->error = 0;
+ scm_request_cluster_init(scmrq);
}
static void scm_ensure_queue_restart(struct scm_blk_dev *bdev)
@@ -181,17 +189,19 @@
blk_delay_queue(bdev->rq, SCM_QUEUE_DELAY);
}
-static void scm_request_requeue(struct scm_request *scmrq)
+void scm_request_requeue(struct scm_request *scmrq)
{
struct scm_blk_dev *bdev = scmrq->bdev;
+ scm_release_cluster(scmrq);
blk_requeue_request(bdev->rq, scmrq->request);
scm_request_done(scmrq);
scm_ensure_queue_restart(bdev);
}
-static void scm_request_finish(struct scm_request *scmrq)
+void scm_request_finish(struct scm_request *scmrq)
{
+ scm_release_cluster(scmrq);
blk_end_request_all(scmrq->request, scmrq->error);
scm_request_done(scmrq);
}
@@ -215,6 +225,16 @@
return;
}
scm_request_init(bdev, scmrq, req);
+ if (!scm_reserve_cluster(scmrq)) {
+ SCM_LOG(5, "cluster busy");
+ scm_request_done(scmrq);
+ return;
+ }
+ if (scm_need_cluster_request(scmrq)) {
+ blk_start_request(req);
+ scm_initiate_cluster_request(scmrq);
+ return;
+ }
scm_request_prepare(scmrq);
blk_start_request(req);
@@ -282,6 +302,13 @@
spin_lock_irqsave(&bdev->lock, flags);
continue;
}
+
+ if (scm_test_cluster_request(scmrq)) {
+ scm_cluster_request_irq(scmrq);
+ spin_lock_irqsave(&bdev->lock, flags);
+ continue;
+ }
+
scm_request_finish(scmrq);
atomic_dec(&bdev->queued_reqs);
spin_lock_irqsave(&bdev->lock, flags);
@@ -325,6 +352,7 @@
blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
blk_queue_max_segments(rq, nr_max_blk);
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq);
+ scm_blk_dev_cluster_setup(bdev);
bdev->gendisk = alloc_disk(SCM_NR_PARTS);
if (!bdev->gendisk)
@@ -370,7 +398,10 @@
static int __init scm_blk_init(void)
{
- int ret;
+ int ret = -EINVAL;
+
+ if (!scm_cluster_size_valid())
+ goto out;
ret = register_blkdev(0, "scm");
if (ret < 0)
diff --git a/drivers/s390/block/scm_blk.h b/drivers/s390/block/scm_blk.h
index 5aba561..7ac6bad 100644
--- a/drivers/s390/block/scm_blk.h
+++ b/drivers/s390/block/scm_blk.h
@@ -22,6 +22,9 @@
spinlock_t lock; /* guard the rest of the blockdev */
atomic_t queued_reqs;
struct list_head finished_requests;
+#ifdef CONFIG_SCM_BLOCK_CLUSTER_WRITE
+ struct list_head cluster_list;
+#endif
};
struct scm_request {
@@ -32,6 +35,13 @@
struct list_head list;
u8 retries;
int error;
+#ifdef CONFIG_SCM_BLOCK_CLUSTER_WRITE
+ struct {
+ enum {CLUSTER_NONE, CLUSTER_READ, CLUSTER_WRITE} state;
+ struct list_head list;
+ void **buf;
+ } cluster;
+#endif
};
#define to_aobrq(rq) container_of((void *) rq, struct aob_rq_header, data)
@@ -40,9 +50,37 @@
void scm_blk_dev_cleanup(struct scm_blk_dev *);
void scm_blk_irq(struct scm_device *, void *, int);
+void scm_request_finish(struct scm_request *);
+void scm_request_requeue(struct scm_request *);
+
int scm_drv_init(void);
void scm_drv_cleanup(void);
+#ifdef CONFIG_SCM_BLOCK_CLUSTER_WRITE
+void __scm_free_rq_cluster(struct scm_request *);
+int __scm_alloc_rq_cluster(struct scm_request *);
+void scm_request_cluster_init(struct scm_request *);
+bool scm_reserve_cluster(struct scm_request *);
+void scm_release_cluster(struct scm_request *);
+void scm_blk_dev_cluster_setup(struct scm_blk_dev *);
+bool scm_need_cluster_request(struct scm_request *);
+void scm_initiate_cluster_request(struct scm_request *);
+void scm_cluster_request_irq(struct scm_request *);
+bool scm_test_cluster_request(struct scm_request *);
+bool scm_cluster_size_valid(void);
+#else
+#define __scm_free_rq_cluster(scmrq) {}
+#define __scm_alloc_rq_cluster(scmrq) 0
+#define scm_request_cluster_init(scmrq) {}
+#define scm_reserve_cluster(scmrq) true
+#define scm_release_cluster(scmrq) {}
+#define scm_blk_dev_cluster_setup(bdev) {}
+#define scm_need_cluster_request(scmrq) false
+#define scm_initiate_cluster_request(scmrq) {}
+#define scm_cluster_request_irq(scmrq) {}
+#define scm_test_cluster_request(scmrq) false
+#define scm_cluster_size_valid() true
+#endif
extern debug_info_t *scm_debug;
diff --git a/drivers/s390/block/scm_blk_cluster.c b/drivers/s390/block/scm_blk_cluster.c
new file mode 100644
index 0000000..f4bb61b
--- /dev/null
+++ b/drivers/s390/block/scm_blk_cluster.c
@@ -0,0 +1,228 @@
+/*
+ * Block driver for s390 storage class memory.
+ *
+ * Copyright IBM Corp. 2012
+ * Author(s): Sebastian Ott <sebott@linux.vnet.ibm.com>
+ */
+
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/genhd.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <asm/eadm.h>
+#include "scm_blk.h"
+
+static unsigned int write_cluster_size = 64;
+module_param(write_cluster_size, uint, S_IRUGO);
+MODULE_PARM_DESC(write_cluster_size,
+ "Number of pages used for contiguous writes.");
+
+#define CLUSTER_SIZE (write_cluster_size * PAGE_SIZE)
+
+void __scm_free_rq_cluster(struct scm_request *scmrq)
+{
+ int i;
+
+ if (!scmrq->cluster.buf)
+ return;
+
+ for (i = 0; i < 2 * write_cluster_size; i++)
+ free_page((unsigned long) scmrq->cluster.buf[i]);
+
+ kfree(scmrq->cluster.buf);
+}
+
+int __scm_alloc_rq_cluster(struct scm_request *scmrq)
+{
+ int i;
+
+ scmrq->cluster.buf = kzalloc(sizeof(void *) * 2 * write_cluster_size,
+ GFP_KERNEL);
+ if (!scmrq->cluster.buf)
+ return -ENOMEM;
+
+ for (i = 0; i < 2 * write_cluster_size; i++) {
+ scmrq->cluster.buf[i] = (void *) get_zeroed_page(GFP_DMA);
+ if (!scmrq->cluster.buf[i])
+ return -ENOMEM;
+ }
+ INIT_LIST_HEAD(&scmrq->cluster.list);
+ return 0;
+}
+
+void scm_request_cluster_init(struct scm_request *scmrq)
+{
+ scmrq->cluster.state = CLUSTER_NONE;
+}
+
+static bool clusters_intersect(struct scm_request *A, struct scm_request *B)
+{
+ unsigned long firstA, lastA, firstB, lastB;
+
+ firstA = ((u64) blk_rq_pos(A->request) << 9) / CLUSTER_SIZE;
+ lastA = (((u64) blk_rq_pos(A->request) << 9) +
+ blk_rq_bytes(A->request) - 1) / CLUSTER_SIZE;
+
+ firstB = ((u64) blk_rq_pos(B->request) << 9) / CLUSTER_SIZE;
+ lastB = (((u64) blk_rq_pos(B->request) << 9) +
+ blk_rq_bytes(B->request) - 1) / CLUSTER_SIZE;
+
+ return (firstB <= lastA && firstA <= lastB);
+}
+
+bool scm_reserve_cluster(struct scm_request *scmrq)
+{
+ struct scm_blk_dev *bdev = scmrq->bdev;
+ struct scm_request *iter;
+
+ if (write_cluster_size == 0)
+ return true;
+
+ spin_lock(&bdev->lock);
+ list_for_each_entry(iter, &bdev->cluster_list, cluster.list) {
+ if (clusters_intersect(scmrq, iter) &&
+ (rq_data_dir(scmrq->request) == WRITE ||
+ rq_data_dir(iter->request) == WRITE)) {
+ spin_unlock(&bdev->lock);
+ return false;
+ }
+ }
+ list_add(&scmrq->cluster.list, &bdev->cluster_list);
+ spin_unlock(&bdev->lock);
+
+ return true;
+}
+
+void scm_release_cluster(struct scm_request *scmrq)
+{
+ struct scm_blk_dev *bdev = scmrq->bdev;
+ unsigned long flags;
+
+ if (write_cluster_size == 0)
+ return;
+
+ spin_lock_irqsave(&bdev->lock, flags);
+ list_del(&scmrq->cluster.list);
+ spin_unlock_irqrestore(&bdev->lock, flags);
+}
+
+void scm_blk_dev_cluster_setup(struct scm_blk_dev *bdev)
+{
+ INIT_LIST_HEAD(&bdev->cluster_list);
+ blk_queue_io_opt(bdev->rq, CLUSTER_SIZE);
+}
+
+static void scm_prepare_cluster_request(struct scm_request *scmrq)
+{
+ struct scm_blk_dev *bdev = scmrq->bdev;
+ struct scm_device *scmdev = bdev->gendisk->private_data;
+ struct request *req = scmrq->request;
+ struct aidaw *aidaw = scmrq->aidaw;
+ struct msb *msb = &scmrq->aob->msb[0];
+ struct req_iterator iter;
+ struct bio_vec *bv;
+ int i = 0;
+ u64 addr;
+
+ switch (scmrq->cluster.state) {
+ case CLUSTER_NONE:
+ scmrq->cluster.state = CLUSTER_READ;
+ /* fall through */
+ case CLUSTER_READ:
+ scmrq->aob->request.msb_count = 1;
+ msb->bs = MSB_BS_4K;
+ msb->oc = MSB_OC_READ;
+ msb->flags = MSB_FLAG_IDA;
+ msb->data_addr = (u64) aidaw;
+ msb->blk_count = write_cluster_size;
+
+ addr = scmdev->address + ((u64) blk_rq_pos(req) << 9);
+ msb->scm_addr = round_down(addr, CLUSTER_SIZE);
+
+ if (msb->scm_addr !=
+ round_down(addr + (u64) blk_rq_bytes(req) - 1,
+ CLUSTER_SIZE))
+ msb->blk_count = 2 * write_cluster_size;
+
+ for (i = 0; i < msb->blk_count; i++) {
+ aidaw->data_addr = (u64) scmrq->cluster.buf[i];
+ aidaw++;
+ }
+
+ break;
+ case CLUSTER_WRITE:
+ msb->oc = MSB_OC_WRITE;
+
+ for (addr = msb->scm_addr;
+ addr < scmdev->address + ((u64) blk_rq_pos(req) << 9);
+ addr += PAGE_SIZE) {
+ aidaw->data_addr = (u64) scmrq->cluster.buf[i];
+ aidaw++;
+ i++;
+ }
+ rq_for_each_segment(bv, req, iter) {
+ aidaw->data_addr = (u64) page_address(bv->bv_page);
+ aidaw++;
+ i++;
+ }
+ for (; i < msb->blk_count; i++) {
+ aidaw->data_addr = (u64) scmrq->cluster.buf[i];
+ aidaw++;
+ }
+ break;
+ }
+}
+
+bool scm_need_cluster_request(struct scm_request *scmrq)
+{
+ if (rq_data_dir(scmrq->request) == READ)
+ return false;
+
+ return blk_rq_bytes(scmrq->request) < CLUSTER_SIZE;
+}
+
+/* Called with queue lock held. */
+void scm_initiate_cluster_request(struct scm_request *scmrq)
+{
+ scm_prepare_cluster_request(scmrq);
+ if (scm_start_aob(scmrq->aob))
+ scm_request_requeue(scmrq);
+}
+
+bool scm_test_cluster_request(struct scm_request *scmrq)
+{
+ return scmrq->cluster.state != CLUSTER_NONE;
+}
+
+void scm_cluster_request_irq(struct scm_request *scmrq)
+{
+ struct scm_blk_dev *bdev = scmrq->bdev;
+ unsigned long flags;
+
+ switch (scmrq->cluster.state) {
+ case CLUSTER_NONE:
+ BUG();
+ break;
+ case CLUSTER_READ:
+ if (scmrq->error) {
+ scm_request_finish(scmrq);
+ break;
+ }
+ scmrq->cluster.state = CLUSTER_WRITE;
+ spin_lock_irqsave(&bdev->rq_lock, flags);
+ scm_initiate_cluster_request(scmrq);
+ spin_unlock_irqrestore(&bdev->rq_lock, flags);
+ break;
+ case CLUSTER_WRITE:
+ scm_request_finish(scmrq);
+ break;
+ }
+}
+
+bool scm_cluster_size_valid(void)
+{
+ return write_cluster_size == 0 || write_cluster_size == 32 ||
+ write_cluster_size == 64 || write_cluster_size == 128;
+}