storvsc: get rid of bounce buffer

index 9c8db21..072c11e 100644
@@ -393,9 +393,6 @@ static void storvsc_on_channel_callback(void *context);
 struct storvsc_cmd_request {
 	struct scsi_cmnd *cmd;
 
-	unsigned int bounce_sgl_count;
-	struct scatterlist *bounce_sgl;
-
 	struct hv_device *device;
 
 	/* Synchronize the request/response if needed */

@@ -586,241 +583,6 @@ get_in_err:
 
 }
 
-static void destroy_bounce_buffer(struct scatterlist *sgl,
-				  unsigned int sg_count)
-{
-	int i;
-	struct page *page_buf;
-
-	for (i = 0; i < sg_count; i++) {
-		page_buf = sg_page((&sgl[i]));
-		if (page_buf != NULL)
-			__free_page(page_buf);
-	}
-
-	kfree(sgl);
-}
-
-static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
-{
-	int i;
-
-	/* No need to check */
-	if (sg_count < 2)
-		return -1;
-
-	/* We have at least 2 sg entries */
-	for (i = 0; i < sg_count; i++) {
-		if (i == 0) {
-			/* make sure 1st one does not have hole */
-			if (sgl[i].offset + sgl[i].length != PAGE_SIZE)
-				return i;
-		} else if (i == sg_count - 1) {
-			/* make sure last one does not have hole */
-			if (sgl[i].offset != 0)
-				return i;
-		} else {
-			/* make sure no hole in the middle */
-			if (sgl[i].length != PAGE_SIZE || sgl[i].offset != 0)
-				return i;
-		}
-	}
-	return -1;
-}
-
-static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl,
-						unsigned int sg_count,
-						unsigned int len,
-						int write)
-{
-	int i;
-	int num_pages;
-	struct scatterlist *bounce_sgl;
-	struct page *page_buf;
-	unsigned int buf_len = ((write == WRITE_TYPE) ? 0 : PAGE_SIZE);
-
-	num_pages = ALIGN(len, PAGE_SIZE) >> PAGE_SHIFT;
-
-	bounce_sgl = kcalloc(num_pages, sizeof(struct scatterlist), GFP_ATOMIC);
-	if (!bounce_sgl)
-		return NULL;
-
-	sg_init_table(bounce_sgl, num_pages);
-	for (i = 0; i < num_pages; i++) {
-		page_buf = alloc_page(GFP_ATOMIC);
-		if (!page_buf)
-			goto cleanup;
-		sg_set_page(&bounce_sgl[i], page_buf, buf_len, 0);
-	}
-
-	return bounce_sgl;
-
-cleanup:
-	destroy_bounce_buffer(bounce_sgl, num_pages);
-	return NULL;
-}
-
-/* Assume the original sgl has enough room */
-static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
-					    struct scatterlist *bounce_sgl,
-					    unsigned int orig_sgl_count,
-					    unsigned int bounce_sgl_count)
-{
-	int i;
-	int j = 0;
-	unsigned long src, dest;
-	unsigned int srclen, destlen, copylen;
-	unsigned int total_copied = 0;
-	unsigned long bounce_addr = 0;
-	unsigned long dest_addr = 0;
-	unsigned long flags;
-	struct scatterlist *cur_dest_sgl;
-	struct scatterlist *cur_src_sgl;
-
-	local_irq_save(flags);
-	cur_dest_sgl = orig_sgl;
-	cur_src_sgl = bounce_sgl;
-	for (i = 0; i < orig_sgl_count; i++) {
-		dest_addr = (unsigned long)
-				kmap_atomic(sg_page(cur_dest_sgl)) +
-				cur_dest_sgl->offset;
-		dest = dest_addr;
-		destlen = cur_dest_sgl->length;
-
-		if (bounce_addr == 0)
-			bounce_addr = (unsigned long)kmap_atomic(
-							sg_page(cur_src_sgl));
-
-		while (destlen) {
-			src = bounce_addr + cur_src_sgl->offset;
-			srclen = cur_src_sgl->length - cur_src_sgl->offset;
-
-			copylen = min(srclen, destlen);
-			memcpy((void *)dest, (void *)src, copylen);
-
-			total_copied += copylen;
-			cur_src_sgl->offset += copylen;
-			destlen -= copylen;
-			dest += copylen;
-
-			if (cur_src_sgl->offset == cur_src_sgl->length) {
-				/* full */
-				kunmap_atomic((void *)bounce_addr);
-				j++;
-
-				/*
-				 * It is possible that the number of elements
-				 * in the bounce buffer may not be equal to
-				 * the number of elements in the original
-				 * scatter list. Handle this correctly.
-				 */
-
-				if (j == bounce_sgl_count) {
-					/*
-					 * We are done; cleanup and return.
-					 */
-					kunmap_atomic((void *)(dest_addr -
-						cur_dest_sgl->offset));
-					local_irq_restore(flags);
-					return total_copied;
-				}
-
-				/* if we need to use another bounce buffer */
-				if (destlen || i != orig_sgl_count - 1) {
-					cur_src_sgl = sg_next(cur_src_sgl);
-					bounce_addr = (unsigned long)
-							kmap_atomic(
-							sg_page(cur_src_sgl));
-				}
-			} else if (destlen == 0 && i == orig_sgl_count - 1) {
-				/* unmap the last bounce that is < PAGE_SIZE */
-				kunmap_atomic((void *)bounce_addr);
-			}
-		}
-
-		kunmap_atomic((void *)(dest_addr - cur_dest_sgl->offset));
-		cur_dest_sgl = sg_next(cur_dest_sgl);
-	}
-
-	local_irq_restore(flags);
-
-	return total_copied;
-}
-
-/* Assume the bounce_sgl has enough room ie using the create_bounce_buffer() */
-static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
-					  struct scatterlist *bounce_sgl,
-					  unsigned int orig_sgl_count)
-{
-	int i;
-	int j = 0;
-	unsigned long src, dest;
-	unsigned int srclen, destlen, copylen;
-	unsigned int total_copied = 0;
-	unsigned long bounce_addr = 0;
-	unsigned long src_addr = 0;
-	unsigned long flags;
-	struct scatterlist *cur_src_sgl;
-	struct scatterlist *cur_dest_sgl;
-
-	local_irq_save(flags);
-
-	cur_src_sgl = orig_sgl;
-	cur_dest_sgl = bounce_sgl;
-
-	for (i = 0; i < orig_sgl_count; i++) {
-		src_addr = (unsigned long)
-				kmap_atomic(sg_page(cur_src_sgl)) +
-				cur_src_sgl->offset;
-		src = src_addr;
-		srclen = cur_src_sgl->length;
-
-		if (bounce_addr == 0)
-			bounce_addr = (unsigned long)
-					kmap_atomic(sg_page(cur_dest_sgl));
-
-		while (srclen) {
-			/* assume bounce offset always == 0 */
-			dest = bounce_addr + cur_dest_sgl->length;
-			destlen = PAGE_SIZE - cur_dest_sgl->length;
-
-			copylen = min(srclen, destlen);
-			memcpy((void *)dest, (void *)src, copylen);
-
-			total_copied += copylen;
-			cur_dest_sgl->length += copylen;
-			srclen -= copylen;
-			src += copylen;
-
-			if (cur_dest_sgl->length == PAGE_SIZE) {
-				/* full..move to next entry */
-				kunmap_atomic((void *)bounce_addr);
-				bounce_addr = 0;
-				j++;
-			}
-
-			/* if we need to use another bounce buffer */
-			if (srclen && bounce_addr == 0) {
-				cur_dest_sgl = sg_next(cur_dest_sgl);
-				bounce_addr = (unsigned long)
-						kmap_atomic(
-						sg_page(cur_dest_sgl));
-			}
-
-		}
-
-		kunmap_atomic((void *)(src_addr - cur_src_sgl->offset));
-		cur_src_sgl = sg_next(cur_src_sgl);
-	}
-
-	if (bounce_addr)
-		kunmap_atomic((void *)bounce_addr);
-
-	local_irq_restore(flags);
-
-	return total_copied;
-}
-
 static void handle_sc_creation(struct vmbus_channel *new_sc)
 {
 	struct hv_device *device = new_sc->primary_channel->device_obj;

@@ -1171,15 +933,6 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
 	host = stor_dev->host;
 
 	vm_srb = &cmd_request->vstor_packet.vm_srb;
-	if (cmd_request->bounce_sgl_count) {
-		if (vm_srb->data_in == READ_TYPE)
-			copy_from_bounce_buffer(scsi_sglist(scmnd),
-					cmd_request->bounce_sgl,
-					scsi_sg_count(scmnd),
-					cmd_request->bounce_sgl_count);
-		destroy_bounce_buffer(cmd_request->bounce_sgl,
-					cmd_request->bounce_sgl_count);
-	}
 
 	scmnd->result = vm_srb->scsi_status;
 

@@ -1474,6 +1227,9 @@ static int storvsc_device_configure(struct scsi_device *sdevice)
 
 	blk_queue_rq_timeout(sdevice->request_queue, (storvsc_timeout * HZ));
 
+	/* Ensure there are no gaps in presented sgls */
+	blk_queue_virt_boundary(sdevice->request_queue, PAGE_SIZE - 1);
+
 	sdevice->no_write_same = 1;
 
 	/*

@@ -1691,40 +1447,13 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
 	payload_sz = sizeof(cmd_request->mpb);
 
 	if (sg_count) {
-		/* check if we need to bounce the sgl */
-		if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1) {
-			cmd_request->bounce_sgl =
-				create_bounce_buffer(sgl, sg_count,
-						     length,
-						     vm_srb->data_in);
-			if (!cmd_request->bounce_sgl)
-				return SCSI_MLQUEUE_HOST_BUSY;
-
-			cmd_request->bounce_sgl_count =
-				ALIGN(length, PAGE_SIZE) >> PAGE_SHIFT;
-
-			if (vm_srb->data_in == WRITE_TYPE)
-				copy_to_bounce_buffer(sgl,
-					cmd_request->bounce_sgl, sg_count);
-
-			sgl = cmd_request->bounce_sgl;
-			sg_count = cmd_request->bounce_sgl_count;
-		}
-
-
 		if (sg_count > MAX_PAGE_BUFFER_COUNT) {
 
 			payload_sz = (sg_count * sizeof(void *) +
 				      sizeof(struct vmbus_packet_mpb_array));
 			payload = kmalloc(payload_sz, GFP_ATOMIC);
-			if (!payload) {
-				if (cmd_request->bounce_sgl_count)
-					destroy_bounce_buffer(
-					cmd_request->bounce_sgl,
-					cmd_request->bounce_sgl_count);
-
-					return SCSI_MLQUEUE_DEVICE_BUSY;
-			}
+			if (!payload)
+				return SCSI_MLQUEUE_DEVICE_BUSY;
 		}
 
 		payload->range.len = length;

@@ -1753,11 +1482,6 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
 
 	if (ret == -EAGAIN) {
 		/* no more space */
-
-		if (cmd_request->bounce_sgl_count)
-			destroy_bounce_buffer(cmd_request->bounce_sgl,
-					cmd_request->bounce_sgl_count);
-
 		return SCSI_MLQUEUE_DEVICE_BUSY;
 	}