Re: [Patch v2 2/3] Drivers: hv: add Azure Blob driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 26. 06. 21, 8:30, longli@xxxxxxxxxxxxxxxxx wrote:
Azure Blob storage provides scalable and durable data storage for Azure.
(https://azure.microsoft.com/en-us/services/storage/blobs/)

This driver adds support for accelerated access to Azure Blob storage. As an
alternative to REST APIs, it provides a fast data path that uses host native
network stack and secure direct data link for storage server access.

...
Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>

I am just curious, why am I CCed? Anyway, some comments below:

--- /dev/null
+++ b/drivers/hv/azure_blob.c
@@ -0,0 +1,655 @@
...
+static void az_blob_on_channel_callback(void *context)
+{
+	struct vmbus_channel *channel = (struct vmbus_channel *)context;

Have you fed this patch through checkpatch?

+	const struct vmpacket_descriptor *desc;
+
+	az_blob_dbg("entering interrupt from vmbus\n");
+	foreach_vmbus_pkt(desc, channel) {
+		struct az_blob_vsp_request_ctx *request_ctx;
+		struct az_blob_vsp_response *response;
+		u64 cmd_rqst = vmbus_request_addr(&channel->requestor,
+					desc->trans_id);
+		if (cmd_rqst == VMBUS_RQST_ERROR) {
+			az_blob_err("incorrect transaction id %llu\n",
+				desc->trans_id);
+			continue;
+		}
+		request_ctx = (struct az_blob_vsp_request_ctx *) cmd_rqst;
+		response = hv_pkt_data(desc);
+
+		az_blob_dbg("got response for request %pUb status %u "
+			"response_len %u\n",
+			&request_ctx->request->guid, response->error,
+			response->response_len);
+		request_ctx->request->response.status = response->error;
+		request_ctx->request->response.response_len =
+			response->response_len;
+		complete(&request_ctx->wait_vsp);
+	}
+
+}
...
+static long az_blob_ioctl_user_request(struct file *filp, unsigned long arg)
+{
+	struct az_blob_device *dev = &az_blob_dev;
+	struct az_blob_file_ctx *file_ctx = filp->private_data;
+	char __user *argp = (char __user *) arg;
+	struct az_blob_request_sync request;
+	struct az_blob_vsp_request_ctx request_ctx;
+	unsigned long flags;
+	int ret;
+	size_t request_start, request_num_pages = 0;
+	size_t response_start, response_num_pages = 0;
+	size_t data_start, data_num_pages = 0, total_num_pages;
+	struct page **request_pages = NULL, **response_pages = NULL;
+	struct page **data_pages = NULL;
+	struct vmbus_packet_mpb_array *desc;
+	u64 *pfn_array;
+	int desc_size;
+	int page_idx;
+	struct az_blob_vsp_request *vsp_request;

Ugh, see further.

+
+	/* Fast fail if device is being removed */
+	if (dev->removing)
+		return -ENODEV;
+
+	if (!az_blob_safe_file_access(filp)) {
+		az_blob_dbg("process %d(%s) changed security contexts after"
+			" opening file descriptor\n",
+			task_tgid_vnr(current), current->comm);
+		return -EACCES;
+	}
+
+	if (copy_from_user(&request, argp, sizeof(request))) {
+		az_blob_dbg("don't have permission to user provided buffer\n");
+		return -EFAULT;
+	}
+
+	az_blob_dbg("az_blob ioctl request guid %pUb timeout %u request_len %u"
+		" response_len %u data_len %u request_buffer %llx "
+		"response_buffer %llx data_buffer %llx\n",
+		&request.guid, request.timeout, request.request_len,
+		request.response_len, request.data_len, request.request_buffer,
+		request.response_buffer, request.data_buffer);
+
+	if (!request.request_len || !request.response_len)
+		return -EINVAL;
+
+	if (request.data_len && request.data_len < request.data_valid)
+		return -EINVAL;
+
+	init_completion(&request_ctx.wait_vsp);
+	request_ctx.request = &request;
+
+	/*
+	 * Need to set rw to READ to have page table set up for passing to VSP.
+	 * Setting it to WRITE will cause the page table entry not allocated
+	 * as it's waiting on Copy-On-Write on next page fault. This doesn't
+	 * work in this scenario because VSP wants all the pages to be present.
+	 */
+	ret = get_buffer_pages(READ, (void __user *) request.request_buffer,

Does this need __force for sparse not to complain?

+		request.request_len, &request_pages, &request_start,
+		&request_num_pages);
+	if (ret)
+		goto get_user_page_failed;
+
+	ret = get_buffer_pages(READ, (void __user *) request.response_buffer,
+		request.response_len, &response_pages, &response_start,
+		&response_num_pages);
+	if (ret)
+		goto get_user_page_failed;
+
+	if (request.data_len) {
+		ret = get_buffer_pages(READ,
+			(void __user *) request.data_buffer, request.data_len,
+			&data_pages, &data_start, &data_num_pages);
+		if (ret)
+			goto get_user_page_failed;
+	}
+
+	total_num_pages = request_num_pages + response_num_pages +
+				data_num_pages;
+	if (total_num_pages > AZ_BLOB_MAX_PAGES) {
+		az_blob_dbg("number of DMA pages %lu buffer exceeding %u\n",
+			total_num_pages, AZ_BLOB_MAX_PAGES);
+		ret = -EINVAL;
+		goto get_user_page_failed;
+	}
+
+	/* Construct a VMBUS packet and send it over to VSP */
+	desc_size = sizeof(struct vmbus_packet_mpb_array) +
+			sizeof(u64) * total_num_pages;
+	desc = kzalloc(desc_size, GFP_KERNEL);

Smells like a call for struct_size().

+	vsp_request = kzalloc(sizeof(*vsp_request), GFP_KERNEL);
+	if (!desc || !vsp_request) {
+		kfree(desc);
+		kfree(vsp_request);
+		ret = -ENOMEM;
+		goto get_user_page_failed;
+	}
+
+	desc->range.offset = 0;
+	desc->range.len = total_num_pages * PAGE_SIZE;
+	pfn_array = desc->range.pfn_array;
+	page_idx = 0;
+
+	if (request.data_len) {
+		fill_in_page_buffer(pfn_array, &page_idx, data_pages,
+			data_num_pages);
+		vsp_request->data_buffer_offset = data_start;
+		vsp_request->data_buffer_length = request.data_len;
+		vsp_request->data_buffer_valid = request.data_valid;
+	}
+
+	fill_in_page_buffer(pfn_array, &page_idx, request_pages,
+		request_num_pages);
+	vsp_request->request_buffer_offset = request_start +
+						data_num_pages * PAGE_SIZE;
+	vsp_request->request_buffer_length = request.request_len;
+
+	fill_in_page_buffer(pfn_array, &page_idx, response_pages,
+		response_num_pages);
+	vsp_request->response_buffer_offset = response_start +
+		(data_num_pages + request_num_pages) * PAGE_SIZE;
+	vsp_request->response_buffer_length = request.response_len;
+
+	vsp_request->version = 0;
+	vsp_request->timeout_ms = request.timeout;
+	vsp_request->operation_type = AZ_BLOB_DRIVER_USER_REQUEST;
+	guid_copy(&vsp_request->transaction_id, &request.guid);
+
+	spin_lock_irqsave(&file_ctx->vsp_pending_lock, flags);
+	list_add_tail(&request_ctx.list, &file_ctx->vsp_pending_requests);
+	spin_unlock_irqrestore(&file_ctx->vsp_pending_lock, flags);
+
+	az_blob_dbg("sending request to VSP\n");
+	az_blob_dbg("desc_size %u desc->range.len %u desc->range.offset %u\n",
+		desc_size, desc->range.len, desc->range.offset);
+	az_blob_dbg("vsp_request data_buffer_offset %u data_buffer_length %u "
+		"data_buffer_valid %u request_buffer_offset %u "
+		"request_buffer_length %u response_buffer_offset %u "
+		"response_buffer_length %u\n",
+		vsp_request->data_buffer_offset,
+		vsp_request->data_buffer_length,
+		vsp_request->data_buffer_valid,
+		vsp_request->request_buffer_offset,
+		vsp_request->request_buffer_length,
+		vsp_request->response_buffer_offset,
+		vsp_request->response_buffer_length);
+
+	ret = vmbus_sendpacket_mpb_desc(dev->device->channel, desc, desc_size,
+		vsp_request, sizeof(*vsp_request), (u64) &request_ctx);
+
+	kfree(desc);
+	kfree(vsp_request);
+	if (ret)
+		goto vmbus_send_failed;
+
+	wait_for_completion(&request_ctx.wait_vsp);

Provided this is ioctl, this should likely be interruptible. You don't want to account to I/O load. The same likely for az_blob_fop_release.

+
+	/*
+	 * At this point, the response is already written to request
+	 * by VMBUS completion handler, copy them to user-mode buffers
+	 * and return to user-mode
+	 */
+	if (copy_to_user(argp +
+			offsetof(struct az_blob_request_sync,
+				response.status),
+			&request.response.status,

This is ugly, why don't you make argp the appropriate pointer instead of char *? You'd need not do copy_to_user twice then, right?

+			sizeof(request.response.status))) {
+		ret = -EFAULT;
+		goto vmbus_send_failed;
+	}
+
+	if (copy_to_user(argp +
+			offsetof(struct az_blob_request_sync,
+				response.response_len),

The same here.

+			&request.response.response_len,
+			sizeof(request.response.response_len)))
+		ret = -EFAULT;
+
+vmbus_send_failed:
+	spin_lock_irqsave(&file_ctx->vsp_pending_lock, flags);
+	list_del(&request_ctx.list);
+	if (list_empty(&file_ctx->vsp_pending_requests))
+		wake_up(&file_ctx->wait_vsp_pending);
+	spin_unlock_irqrestore(&file_ctx->vsp_pending_lock, flags);
+
+get_user_page_failed:
+	free_buffer_pages(request_num_pages, request_pages);
+	free_buffer_pages(response_num_pages, response_pages);
+	free_buffer_pages(data_num_pages, data_pages);
+
+	return ret;
+}

This function is overly long. Care to split it (e.g. moving away the initialization of the structs and the debug stuff)?

+
+static long az_blob_fop_ioctl(struct file *filp, unsigned int cmd,
+	unsigned long arg)
+{
+	long ret = -EIO;

EINVAL would be more appropriate.

+
+	switch (cmd) {
+	case IOCTL_AZ_BLOB_DRIVER_USER_REQUEST:
+		if (_IOC_SIZE(cmd) != sizeof(struct az_blob_request_sync))
+			return -EINVAL;

How can that happen, provided the switch (cmd) and case?

+		ret = az_blob_ioctl_user_request(filp, arg);
+		break;

Simply:
return az_blob_ioctl_user_request(filp, arg);

+
+	default:
+		az_blob_dbg("unrecognized IOCTL code %u\n", cmd);
+	}
+
+	return ret;

So return -EINVAL here directly now.

+}
...
+static int az_blob_connect_to_vsp(struct hv_device *device, u32 ring_size)
+{
+	int ret;
...
+	int rc;


Sometimes ret, sometimes rc, could you unify the two?

+static int __init az_blob_drv_init(void)
+{
+	int ret;
+
+	ret = vmbus_driver_register(&az_blob_drv);
+	return ret;

Simply:
return vmbus_driver_register(&az_blob_drv);

regards,
--
--
js
suse labs



[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux