[PATCH v6 07/18] s390/dasd: Add infrastructure for ESE full-track write

[Stefan Haberland <sth@linux.ibm.com>]

Add the driver internals to build WRITE_FULL_TRACK FCX channel programs
in response to unformatted tracks on ESE devices.

struct dasd_ccw_req: filldata, a pointer to the per-track metadata (an R0
record and the count records) that the WRITE_FULL_TRACK TIDAWs point at,
and format/start_trk/end_trk/collision that link a request to its
format-track guard entry so an overlapping format request can be detected.

struct dasd_device: fill_mem/fill_chunks pool for those buffers and a
zeroed nulldata page used as the data source for pad records.

struct dasd_block: ese_staging/ese_lock, a hardirq-safe staging list. An
ESE format CQR is created in the interrupt handler but has to be enqueued
on ccw_queue under queue_lock; taking queue_lock while the ccwdev_lock is
held there would invert the lock order, so the CQR is staged under ese_lock
and dasd_block_tasklet splices it onto ccw_queue. Existing locking is
unchanged.

Add CQR states DASD_CQR_ABORT/ABORTED to retire the origin CQR of a
replaced write without completing it to the block layer, and struct
eckd_r0 for the track header record.

The CCW and ESE format pools are enlarged (a full-track ITCW is roughly
twice a plain track-mode one) to keep two maximum-size requests in flight.

Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
---
 drivers/s390/block/dasd.c      | 93 ++++++++++++++++++++++++++++------
 drivers/s390/block/dasd_eckd.c | 11 ++++
 drivers/s390/block/dasd_eckd.h |  5 ++
 drivers/s390/block/dasd_int.h  | 19 +++++++
 4 files changed, 113 insertions(+), 15 deletions(-)

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 9c24ae54b2d5..50219c7ff3dc 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -91,31 +91,53 @@ struct dasd_device *dasd_alloc_device(void)
 	if (!device)
 		return ERR_PTR(-ENOMEM);
 
-	/* Get two pages for normal block device operations. */
-	device->ccw_mem = (void *)__get_free_pages(GFP_KERNEL | GFP_DMA, 1);
+	/*
+	 * Four pages: a full-track ITCW is roughly twice the size of a plain
+	 * track-mode one, so this keeps two maximum-size requests in flight.
+	 */
+	device->ccw_mem = (void *)__get_free_pages(GFP_KERNEL | GFP_DMA, 2);
 	if (!device->ccw_mem) {
 		kfree(device);
 		return ERR_PTR(-ENOMEM);
 	}
+	/* per-request track-filler buffers (R0 + count records) */
+	device->fill_mem = (void *)__get_free_pages(GFP_KERNEL | GFP_DMA, 1);
+	if (!device->fill_mem) {
+		free_pages((unsigned long)device->ccw_mem, 2);
+		kfree(device);
+		return ERR_PTR(-ENOMEM);
+	}
 	/* Get one page for error recovery. */
 	device->erp_mem = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
 	if (!device->erp_mem) {
-		free_pages((unsigned long) device->ccw_mem, 1);
+		free_pages((unsigned long)device->fill_mem, 1);
+		free_pages((unsigned long)device->ccw_mem, 2);
 		kfree(device);
 		return ERR_PTR(-ENOMEM);
 	}
-	/* Get two pages for ese format. */
-	device->ese_mem = (void *)__get_free_pages(GFP_KERNEL | GFP_DMA, 1);
+	/* sized like ccw_chunks: two max-size NRF format requests in flight */
+	device->ese_mem = (void *)__get_free_pages(GFP_KERNEL | GFP_DMA, 2);
 	if (!device->ese_mem) {
-		free_page((unsigned long) device->erp_mem);
-		free_pages((unsigned long) device->ccw_mem, 1);
+		free_page((unsigned long)device->erp_mem);
+		free_pages((unsigned long)device->fill_mem, 1);
+		free_pages((unsigned long)device->ccw_mem, 2);
+		kfree(device);
+		return ERR_PTR(-ENOMEM);
+	}
+	device->nulldata = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!device->nulldata) {
+		free_page((unsigned long)device->erp_mem);
+		free_pages((unsigned long)device->fill_mem, 1);
+		free_pages((unsigned long)device->ccw_mem, 2);
+		free_pages((unsigned long)device->ese_mem, 2);
 		kfree(device);
 		return ERR_PTR(-ENOMEM);
 	}
 
-	dasd_init_chunklist(&device->ccw_chunks, device->ccw_mem, PAGE_SIZE*2);
+	dasd_init_chunklist(&device->ccw_chunks, device->ccw_mem, PAGE_SIZE * 4);
+	dasd_init_chunklist(&device->fill_chunks, device->fill_mem, PAGE_SIZE * 2);
 	dasd_init_chunklist(&device->erp_chunks, device->erp_mem, PAGE_SIZE);
-	dasd_init_chunklist(&device->ese_chunks, device->ese_mem, PAGE_SIZE * 2);
+	dasd_init_chunklist(&device->ese_chunks, device->ese_mem, PAGE_SIZE * 4);
 	spin_lock_init(&device->mem_lock);
 	atomic_set(&device->tasklet_scheduled, 0);
 	tasklet_init(&device->tasklet, dasd_device_tasklet,
@@ -138,9 +160,11 @@ struct dasd_device *dasd_alloc_device(void)
 void dasd_free_device(struct dasd_device *device)
 {
 	kfree(device->private);
-	free_pages((unsigned long) device->ese_mem, 1);
-	free_page((unsigned long) device->erp_mem);
-	free_pages((unsigned long) device->ccw_mem, 1);
+	free_pages((unsigned long)device->ese_mem, 2);
+	free_page((unsigned long)device->erp_mem);
+	free_pages((unsigned long)device->fill_mem, 1);
+	free_pages((unsigned long)device->ccw_mem, 2);
+	free_page((unsigned long)device->nulldata);
 	kfree(device);
 }
 
@@ -164,6 +188,8 @@ struct dasd_block *dasd_alloc_block(void)
 	spin_lock_init(&block->queue_lock);
 	INIT_LIST_HEAD(&block->format_list);
 	spin_lock_init(&block->format_lock);
+	INIT_LIST_HEAD(&block->ese_staging);
+	spin_lock_init(&block->ese_lock);
 	timer_setup(&block->timer, dasd_block_timeout, 0);
 	spin_lock_init(&block->profile.lock);
 
@@ -364,7 +390,8 @@ int _wait_for_empty_queues(struct dasd_device *device)
 {
 	if (device->block)
 		return list_empty(&device->ccw_queue) &&
-			list_empty(&device->block->ccw_queue);
+			list_empty(&device->block->ccw_queue) &&
+			list_empty(&device->block->ese_staging);
 	else
 		return list_empty(&device->ccw_queue);
 }
@@ -1224,7 +1251,18 @@ void dasd_sfree_request(struct dasd_ccw_req *cqr, struct dasd_device *device)
 	unsigned long flags;
 
 	spin_lock_irqsave(&device->mem_lock, flags);
-	dasd_free_chunk(&device->ccw_chunks, cqr->mem_chunk);
+	/*
+	 * Free the request block from the pool it came from: smalloc() sets
+	 * mem_chunk (ccw_chunks), fmalloc() leaves it NULL (ese_chunks). A
+	 * full-track request also frees its track-filler buffer.
+	 */
+	if (cqr->filldata)
+		dasd_free_chunk(&device->fill_chunks, cqr->filldata);
+	if (cqr->mem_chunk)
+		dasd_free_chunk(&device->ccw_chunks, cqr->mem_chunk);
+	else
+		dasd_free_chunk(&device->ese_chunks, cqr);
+
 	spin_unlock_irqrestore(&device->mem_lock, flags);
 	dasd_put_device(device);
 }
@@ -1235,6 +1273,8 @@ void dasd_ffree_request(struct dasd_ccw_req *cqr, struct dasd_device *device)
 	unsigned long flags;
 
 	spin_lock_irqsave(&device->mem_lock, flags);
+	if (cqr->filldata)
+		dasd_free_chunk(&device->fill_chunks, cqr->filldata);
 	dasd_free_chunk(&device->ese_chunks, cqr);
 	spin_unlock_irqrestore(&device->mem_lock, flags);
 	dasd_put_device(device);
@@ -1885,6 +1925,10 @@ static void __dasd_process_cqr(struct dasd_device *device,
 	case DASD_CQR_CLEARED:
 		cqr->status = DASD_CQR_TERMINATED;
 		break;
+	case DASD_CQR_ABORT:
+		cqr->status = DASD_CQR_ABORTED;
+		cqr->callback = NULL;
+		break;
 	default:
 		dev_err(&device->cdev->dev,
 			"Unexpected CQR status %02x", cqr->status);
@@ -2212,6 +2256,7 @@ EXPORT_SYMBOL(dasd_add_request_tail);
 void dasd_wakeup_cb(struct dasd_ccw_req *cqr, void *data)
 {
 	spin_lock_irq(get_ccwdev_lock(cqr->startdev->cdev));
+	cqr->endclk = get_tod_clock();
 	cqr->callback_data = DASD_SLEEPON_END_TAG;
 	spin_unlock_irq(get_ccwdev_lock(cqr->startdev->cdev));
 	wake_up(&generic_waitq);
@@ -2773,7 +2818,8 @@ static void __dasd_process_block_ccw_queue(struct dasd_block *block,
 		if (cqr->status != DASD_CQR_DONE &&
 		    cqr->status != DASD_CQR_FAILED &&
 		    cqr->status != DASD_CQR_NEED_ERP &&
-		    cqr->status != DASD_CQR_TERMINATED)
+		    cqr->status != DASD_CQR_TERMINATED &&
+		    cqr->status != DASD_CQR_ABORTED)
 			continue;
 
 		if (cqr->status == DASD_CQR_TERMINATED) {
@@ -2884,6 +2930,14 @@ static void dasd_block_tasklet(unsigned long data)
 	atomic_set(&block->tasklet_scheduled, 0);
 	INIT_LIST_HEAD(&final_queue);
 	spin_lock_irq(&block->queue_lock);
+	/*
+	 * Splice the hardirq-staged ESE format CQRs onto ccw_queue. Splice to
+	 * the tail so an aborted origin request (already on ccw_queue) is
+	 * retired before its format-CQR replacement completes and requeues it.
+	 */
+	spin_lock(&block->ese_lock);
+	list_splice_tail_init(&block->ese_staging, &block->ccw_queue);
+	spin_unlock(&block->ese_lock);
 	/* Finish off requests on ccw queue */
 	__dasd_process_block_ccw_queue(block, &final_queue);
 	spin_unlock_irq(&block->queue_lock);
@@ -2943,6 +2997,15 @@ static int _dasd_requests_to_flushqueue(struct dasd_block *block,
 	int rc, i;
 
 	spin_lock_irqsave(&block->queue_lock, flags);
+	/*
+	 * Splice any hardirq-staged ESE format CQRs onto ccw_queue first so
+	 * they are seen and canceled by the walk below instead of being
+	 * orphaned across this flush / state transition. Mirrors the splice
+	 * in dasd_block_tasklet().
+	 */
+	spin_lock(&block->ese_lock);
+	list_splice_tail_init(&block->ese_staging, &block->ccw_queue);
+	spin_unlock(&block->ese_lock);
 	rc = 0;
 restart:
 	list_for_each_entry_safe(cqr, n, &block->ccw_queue, blocklist) {
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 8192f939aa43..db07fafefe04 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -204,6 +204,17 @@ static void set_ch_t(struct ch_t *geo, __u32 cyl, __u8 head)
 	geo->head |= head;
 }
 
+static void set_chr_t(void *addr, __u32 cyl, __u8 head, __u8 record)
+{
+	struct chr_t *geo = addr;
+
+	geo->cyl = (__u16)cyl;
+	geo->head = cyl >> DASD_EAV_CYL_HI_SHIFT;
+	geo->head <<= DASD_EAV_HEAD_HI_SHIFT;
+	geo->head |= head;
+	geo->record = record;
+}
+
 /*
  * calculate failing track from sense data depending if
  * it is an EAV device or not
diff --git a/drivers/s390/block/dasd_eckd.h b/drivers/s390/block/dasd_eckd.h
index bad7ba666370..0fdb92fdddc8 100644
--- a/drivers/s390/block/dasd_eckd.h
+++ b/drivers/s390/block/dasd_eckd.h
@@ -146,6 +146,11 @@ struct eckd_count {
 	__u16 dl;
 } __attribute__ ((packed));
 
+struct eckd_r0 {
+	struct eckd_count count;
+	__u8 data[8];
+} __packed;
+
 /*
  * Extended Address Volume track address: the head field carries the actual
  * head in its low-order 4 bits; the cylinder bits that do not fit the 16-bit
diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index 99c253421653..0ca039126ae9 100644
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -159,6 +159,11 @@ struct dasd_ccw_req {
 	void *callback_data;
 	unsigned int proc_bytes;	/* bytes for partial completion */
 	unsigned int trkcount;		/* count formatted tracks */
+	void *filldata;			/* address of filler data */
+	struct dasd_format_entry *format;
+	sector_t start_trk;
+	sector_t end_trk;
+	bool collision;
 };
 
 /*
@@ -170,6 +175,7 @@ struct dasd_ccw_req {
 #define DASD_CQR_IN_ERP 	0x03	/* request is in recovery */
 #define DASD_CQR_FAILED 	0x04	/* request is finally failed */
 #define DASD_CQR_TERMINATED	0x05	/* request was stopped by driver */
+#define DASD_CQR_ABORTED	0x06	/* request was replaced and will be deleted */
 
 #define DASD_CQR_QUEUED 	0x80	/* request is queued to be processed */
 #define DASD_CQR_IN_IO		0x81	/* request is currently in IO */
@@ -177,6 +183,7 @@ struct dasd_ccw_req {
 #define DASD_CQR_CLEAR_PENDING	0x83	/* request is clear pending */
 #define DASD_CQR_CLEARED	0x84	/* request was cleared */
 #define DASD_CQR_SUCCESS	0x85	/* request was successful */
+#define DASD_CQR_ABORT		0x86	/* request was replaced and will not be handled */
 
 /* default expiration time*/
 #define DASD_EXPIRES	  300
@@ -573,9 +580,12 @@ struct dasd_device {
 	struct list_head ccw_queue;
 	spinlock_t mem_lock;
 	void *ccw_mem;
+	void *fill_mem;
 	void *erp_mem;
 	void *ese_mem;
+	void *nulldata;
 	struct list_head ccw_chunks;
+	struct list_head fill_chunks;
 	struct list_head erp_chunks;
 	struct list_head ese_chunks;
 
@@ -640,6 +650,15 @@ struct dasd_block {
 	struct list_head format_list;
 	spinlock_t format_lock;
 	atomic_t trkcount;
+
+	/*
+	 * ESE format CQRs staged from hardirq, spliced into
+	 * ccw_queue in dasd_block_tasklet under queue_lock. Direct enqueue from
+	 * the IRQ handler would invert the queue_lock / ccwdev_lock order.
+	 */
+	struct list_head ese_staging;
+	/* lock for ese_staging */
+	spinlock_t ese_lock;
 };
 
 struct dasd_attention_data {
-- 
2.53.0