nbd: Minimal structured read for client (f140e300) · Commits · SUMMER2020 / students / proj-2021291

block/nbd-client.c

+458 −32

Original line number	Diff line number	Diff line
		@@ -93,7 +93,7 @@ static coroutine_fn void nbd_read_reply_entry(void *opaque)
		if (i >= MAX_NBD_REQUESTS \|\|
		!s->requests[i].coroutine \|\|
		!s->requests[i].receiving \|\|
		nbd_reply_is_structured(&s->reply))
		(nbd_reply_is_structured(&s->reply) && !s->info.structured_reply))
		{
		break;
		}
		@@ -141,6 +141,7 @@ static int nbd_co_send_request(BlockDriverState *bs,
		assert(i < MAX_NBD_REQUESTS);

		s->requests[i].coroutine = qemu_coroutine_self();
		s->requests[i].offset = request->from;
		s->requests[i].receiving = false;

		request->handle = INDEX_TO_HANDLE(s, i);
		@@ -181,75 +182,489 @@ err:
		return rc;
		}

		static int nbd_co_receive_reply(NBDClientSession *s,
		uint64_t handle,
		QEMUIOVector *qiov)
		static inline uint16_t payload_advance16(uint8_t **payload)
		{
		*payload += 2;
		return lduw_be_p(*payload - 2);
		}

		static inline uint32_t payload_advance32(uint8_t **payload)
		{
		*payload += 4;
		return ldl_be_p(*payload - 4);
		}

		static inline uint64_t payload_advance64(uint8_t **payload)
		{
		*payload += 8;
		return ldq_be_p(*payload - 8);
		}

		static int nbd_parse_offset_hole_payload(NBDStructuredReplyChunk *chunk,
		uint8_t *payload, uint64_t orig_offset,
		QEMUIOVector qiov, Error *errp)
		{
		uint64_t offset;
		uint32_t hole_size;

		if (chunk->length != sizeof(offset) + sizeof(hole_size)) {
		error_setg(errp, "Protocol error: invalid payload for "
		"NBD_REPLY_TYPE_OFFSET_HOLE");
		return -EINVAL;
		}

		offset = payload_advance64(&payload);
		hole_size = payload_advance32(&payload);

		if (offset < orig_offset \|\| hole_size > qiov->size \|\|
		offset > orig_offset + qiov->size - hole_size) {
		error_setg(errp, "Protocol error: server sent chunk exceeding requested"
		" region");
		return -EINVAL;
		}

		qemu_iovec_memset(qiov, offset - orig_offset, 0, hole_size);

		return 0;
		}

		/* nbd_parse_error_payload
		* on success @errp contains message describing nbd error reply
		*/
		static int nbd_parse_error_payload(NBDStructuredReplyChunk *chunk,
		uint8_t payload, int request_ret,
		Error **errp)
		{
		uint32_t error;
		uint16_t message_size;

		assert(chunk->type & (1 << 15));

		if (chunk->length < sizeof(error) + sizeof(message_size)) {
		error_setg(errp,
		"Protocol error: invalid payload for structured error");
		return -EINVAL;
		}

		error = nbd_errno_to_system_errno(payload_advance32(&payload));
		if (error == 0) {
		error_setg(errp, "Protocol error: server sent structured error chunk"
		"with error = 0");
		return -EINVAL;
		}

		*request_ret = -error;
		message_size = payload_advance16(&payload);

		if (message_size > chunk->length - sizeof(error) - sizeof(message_size)) {
		error_setg(errp, "Protocol error: server sent structured error chunk"
		"with incorrect message size");
		return -EINVAL;
		}

		/* TODO: Add a trace point to mention the server complaint */

		/* TODO handle ERROR_OFFSET */

		return 0;
		}

		static int nbd_co_receive_offset_data_payload(NBDClientSession *s,
		uint64_t orig_offset,
		QEMUIOVector qiov, Error *errp)
		{
		QEMUIOVector sub_qiov;
		uint64_t offset;
		size_t data_size;
		int ret;
		NBDStructuredReplyChunk *chunk = &s->reply.structured;

		assert(nbd_reply_is_structured(&s->reply));

		if (chunk->length < sizeof(offset)) {
		error_setg(errp, "Protocol error: invalid payload for "
		"NBD_REPLY_TYPE_OFFSET_DATA");
		return -EINVAL;
		}

		if (nbd_read(s->ioc, &offset, sizeof(offset), errp) < 0) {
		return -EIO;
		}
		be64_to_cpus(&offset);

		data_size = chunk->length - sizeof(offset);
		if (offset < orig_offset \|\| data_size > qiov->size \|\|
		offset > orig_offset + qiov->size - data_size) {
		error_setg(errp, "Protocol error: server sent chunk exceeding requested"
		" region");
		return -EINVAL;
		}

		qemu_iovec_init(&sub_qiov, qiov->niov);
		qemu_iovec_concat(&sub_qiov, qiov, offset - orig_offset, data_size);
		ret = qio_channel_readv_all(s->ioc, sub_qiov.iov, sub_qiov.niov, errp);
		qemu_iovec_destroy(&sub_qiov);

		return ret < 0 ? -EIO : 0;
		}

		#define NBD_MAX_MALLOC_PAYLOAD 1000
		/* nbd_co_receive_structured_payload
		*/
		static coroutine_fn int nbd_co_receive_structured_payload(
		NBDClientSession s, void payload, Error *errp)
		{
		int ret;
		uint32_t len;

		assert(nbd_reply_is_structured(&s->reply));

		len = s->reply.structured.length;

		if (len == 0) {
		return 0;
		}

		if (payload == NULL) {
		error_setg(errp, "Unexpected structured payload");
		return -EINVAL;
		}

		if (len > NBD_MAX_MALLOC_PAYLOAD) {
		error_setg(errp, "Payload too large");
		return -EINVAL;
		}

		*payload = g_new(char, len);
		ret = nbd_read(s->ioc, *payload, len, errp);
		if (ret < 0) {
		g_free(*payload);
		*payload = NULL;
		return ret;
		}

		return 0;
		}

		/* nbd_co_do_receive_one_chunk
		* for simple reply:
		* set request_ret to received reply error
		* if qiov is not NULL: read payload to @qiov
		* for structured reply chunk:
		* if error chunk: read payload, set @request_ret, do not set @payload
		* else if offset_data chunk: read payload data to @qiov, do not set @payload
		* else: read payload to @payload
		*
		* If function fails, @errp contains corresponding error message, and the
		* connection with the server is suspect. If it returns 0, then the
		* transaction succeeded (although @request_ret may be a negative errno
		* corresponding to the server's error reply), and errp is unchanged.
		*/
		static coroutine_fn int nbd_co_do_receive_one_chunk(
		NBDClientSession *s, uint64_t handle, bool only_structured,
		int request_ret, QEMUIOVector qiov, void payload, Error errp)
		{
		int ret;
		int i = HANDLE_TO_INDEX(s, handle);
		void *local_payload = NULL;
		NBDStructuredReplyChunk *chunk;

		if (payload) {
		*payload = NULL;
		}
		*request_ret = 0;

		/* Wait until we're woken up by nbd_read_reply_entry. */
		s->requests[i].receiving = true;
		qemu_coroutine_yield();
		s->requests[i].receiving = false;
		if (!s->ioc \|\| s->quit) {
		ret = -EIO;
		} else {
		error_setg(errp, "Connection closed");
		return -EIO;
		}

		assert(s->reply.handle == handle);
		ret = -nbd_errno_to_system_errno(s->reply.simple.error);
		if (qiov && ret == 0) {
		if (qio_channel_readv_all(s->ioc, qiov->iov, qiov->niov,
		NULL) < 0) {
		ret = -EIO;
		s->quit = true;

		if (nbd_reply_is_simple(&s->reply)) {
		if (only_structured) {
		error_setg(errp, "Protocol error: simple reply when structured "
		"reply chunk was expected");
		return -EINVAL;
		}

		*request_ret = -nbd_errno_to_system_errno(s->reply.simple.error);
		if (*request_ret < 0 \|\| !qiov) {
		return 0;
		}

		/* Tell the read handler to read another header. */
		s->reply.handle = 0;
		return qio_channel_readv_all(s->ioc, qiov->iov, qiov->niov,
		errp) < 0 ? -EIO : 0;
		}

		s->requests[i].coroutine = NULL;
		/* handle structured reply chunk */
		assert(s->info.structured_reply);
		chunk = &s->reply.structured;

		if (chunk->type == NBD_REPLY_TYPE_NONE) {
		if (!(chunk->flags & NBD_REPLY_FLAG_DONE)) {
		error_setg(errp, "Protocol error: NBD_REPLY_TYPE_NONE chunk without"
		"NBD_REPLY_FLAG_DONE flag set");
		return -EINVAL;
		}
		return 0;
		}

		if (chunk->type == NBD_REPLY_TYPE_OFFSET_DATA) {
		if (!qiov) {
		error_setg(errp, "Unexpected NBD_REPLY_TYPE_OFFSET_DATA chunk");
		return -EINVAL;
		}

		return nbd_co_receive_offset_data_payload(s, s->requests[i].offset,
		qiov, errp);
		}

		if (nbd_reply_type_is_error(chunk->type)) {
		payload = &local_payload;
		}

		ret = nbd_co_receive_structured_payload(s, payload, errp);
		if (ret < 0) {
		return ret;
		}

		if (nbd_reply_type_is_error(chunk->type)) {
		ret = nbd_parse_error_payload(chunk, local_payload, request_ret, errp);
		g_free(local_payload);
		return ret;
		}

		return 0;
		}

		/* nbd_co_receive_one_chunk
		* Read reply, wake up read_reply_co and set s->quit if needed.
		* Return value is a fatal error code or normal nbd reply error code
		*/
		static coroutine_fn int nbd_co_receive_one_chunk(
		NBDClientSession *s, uint64_t handle, bool only_structured,
		QEMUIOVector qiov, NBDReply reply, void payload, Error errp)
		{
		int request_ret;
		int ret = nbd_co_do_receive_one_chunk(s, handle, only_structured,
		&request_ret, qiov, payload, errp);

		if (ret < 0) {
		s->quit = true;
		} else {
		/* For assert at loop start in nbd_read_reply_entry */
		if (reply) {
		*reply = s->reply;
		}
		s->reply.handle = 0;
		ret = request_ret;
		}

		/* Kick the read_reply_co to get the next reply. */
		if (s->read_reply_co) {
		aio_co_wake(s->read_reply_co);
		}

		return ret;
		}

		typedef struct NBDReplyChunkIter {
		int ret;
		Error *err;
		bool done, only_structured;
		} NBDReplyChunkIter;

		static void nbd_iter_error(NBDReplyChunkIter *iter, bool fatal,
		int ret, Error **local_err)
		{
		assert(ret < 0);

		if (fatal \|\| iter->ret == 0) {
		if (iter->ret != 0) {
		error_free(iter->err);
		iter->err = NULL;
		}
		iter->ret = ret;
		error_propagate(&iter->err, *local_err);
		} else {
		error_free(*local_err);
		}

		*local_err = NULL;
		}

		/* NBD_FOREACH_REPLY_CHUNK
		*/
		#define NBD_FOREACH_REPLY_CHUNK(s, iter, handle, structured, \
		qiov, reply, payload) \
		for (iter = (NBDReplyChunkIter) { .only_structured = structured }; \
		nbd_reply_chunk_iter_receive(s, &iter, handle, qiov, reply, payload);)

		/* nbd_reply_chunk_iter_receive
		*/
		static bool nbd_reply_chunk_iter_receive(NBDClientSession *s,
		NBDReplyChunkIter *iter,
		uint64_t handle,
		QEMUIOVector qiov, NBDReply reply,
		void **payload)
		{
		int ret;
		NBDReply local_reply;
		NBDStructuredReplyChunk *chunk;
		Error *local_err = NULL;
		if (s->quit) {
		error_setg(&local_err, "Connection closed");
		nbd_iter_error(iter, true, -EIO, &local_err);
		goto break_loop;
		}

		if (iter->done) {
		/* Previous iteration was last. */
		goto break_loop;
		}

		if (reply == NULL) {
		reply = &local_reply;
		}

		ret = nbd_co_receive_one_chunk(s, handle, iter->only_structured,
		qiov, reply, payload, &local_err);
		if (ret < 0) {
		/* If it is a fatal error s->quit is set by nbd_co_receive_one_chunk */
		nbd_iter_error(iter, s->quit, ret, &local_err);
		}

		/* Do not execute the body of NBD_FOREACH_REPLY_CHUNK for simple reply. */
		if (nbd_reply_is_simple(&s->reply) \|\| s->quit) {
		goto break_loop;
		}

		chunk = &reply->structured;
		iter->only_structured = true;

		if (chunk->type == NBD_REPLY_TYPE_NONE) {
		/* NBD_REPLY_FLAG_DONE is already checked in nbd_co_receive_one_chunk */
		assert(chunk->flags & NBD_REPLY_FLAG_DONE);
		goto break_loop;
		}

		if (chunk->flags & NBD_REPLY_FLAG_DONE) {
		/* This iteration is last. */
		iter->done = true;
		}

		/* Execute the loop body */
		return true;

		break_loop:
		s->requests[HANDLE_TO_INDEX(s, handle)].coroutine = NULL;

		qemu_co_mutex_lock(&s->send_mutex);
		s->in_flight--;
		qemu_co_queue_next(&s->free_sema);
		qemu_co_mutex_unlock(&s->send_mutex);

		return ret;
		return false;
		}

		static int nbd_co_request(BlockDriverState *bs,
		NBDRequest *request,
		QEMUIOVector *qiov)
		static int nbd_co_receive_return_code(NBDClientSession *s, uint64_t handle,
		Error **errp)
		{
		NBDReplyChunkIter iter;

		NBD_FOREACH_REPLY_CHUNK(s, iter, handle, false, NULL, NULL, NULL) {
		/* nbd_reply_chunk_iter_receive does all the work */
		}

		error_propagate(errp, iter.err);
		return iter.ret;
		}

		static int nbd_co_receive_cmdread_reply(NBDClientSession *s, uint64_t handle,
		uint64_t offset, QEMUIOVector *qiov,
		Error **errp)
		{
		NBDReplyChunkIter iter;
		NBDReply reply;
		void *payload = NULL;
		Error *local_err = NULL;

		NBD_FOREACH_REPLY_CHUNK(s, iter, handle, s->info.structured_reply,
		qiov, &reply, &payload)
		{
		NBDClientSession *client = nbd_get_client_session(bs);
		int ret;
		NBDStructuredReplyChunk *chunk = &reply.structured;

		if (qiov) {
		assert(request->type == NBD_CMD_WRITE \|\| request->type == NBD_CMD_READ);
		assert(request->len == iov_size(qiov->iov, qiov->niov));
		assert(nbd_reply_is_structured(&reply));

		switch (chunk->type) {
		case NBD_REPLY_TYPE_OFFSET_DATA:
		/* special cased in nbd_co_receive_one_chunk, data is already
		* in qiov */
		break;
		case NBD_REPLY_TYPE_OFFSET_HOLE:
		ret = nbd_parse_offset_hole_payload(&reply.structured, payload,
		offset, qiov, &local_err);
		if (ret < 0) {
		s->quit = true;
		nbd_iter_error(&iter, true, ret, &local_err);
		}
		break;
		default:
		if (!nbd_reply_type_is_error(chunk->type)) {
		/* not allowed reply type */
		s->quit = true;
		error_setg(&local_err,
		"Unexpected reply type: %d (%s) for CMD_READ",
		chunk->type, nbd_reply_type_lookup(chunk->type));
		nbd_iter_error(&iter, true, -EINVAL, &local_err);
		}
		}

		g_free(payload);
		payload = NULL;
		}

		error_propagate(errp, iter.err);
		return iter.ret;
		}

		static int nbd_co_request(BlockDriverState bs, NBDRequest request,
		QEMUIOVector *write_qiov)
		{
		int ret;
		Error *local_err = NULL;
		NBDClientSession *client = nbd_get_client_session(bs);

		assert(request->type != NBD_CMD_READ);
		if (write_qiov) {
		assert(request->type == NBD_CMD_WRITE);
		assert(request->len == iov_size(write_qiov->iov, write_qiov->niov));
		} else {
		assert(request->type != NBD_CMD_WRITE && request->type != NBD_CMD_READ);
		assert(request->type != NBD_CMD_WRITE);
		}
		ret = nbd_co_send_request(bs, request,
		request->type == NBD_CMD_WRITE ? qiov : NULL);
		ret = nbd_co_send_request(bs, request, write_qiov);
		if (ret < 0) {
		return ret;
		}

		return nbd_co_receive_reply(client, request->handle,
		request->type == NBD_CMD_READ ? qiov : NULL);
		ret = nbd_co_receive_return_code(client, request->handle, &local_err);
		if (local_err) {
		error_report_err(local_err);
		}
		return ret;
		}

		int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
		uint64_t bytes, QEMUIOVector *qiov, int flags)
		{
		int ret;
		Error *local_err = NULL;
		NBDClientSession *client = nbd_get_client_session(bs);
		NBDRequest request = {
		.type = NBD_CMD_READ,
		.from = offset,
		@@ -259,7 +674,17 @@ int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
		assert(bytes <= NBD_MAX_BUFFER_SIZE);
		assert(!flags);

		return nbd_co_request(bs, &request, qiov);
		ret = nbd_co_send_request(bs, &request, NULL);
		if (ret < 0) {
		return ret;
		}

		ret = nbd_co_receive_cmdread_reply(client, request.handle, offset, qiov,
		&local_err);
		if (ret < 0) {
		error_report_err(local_err);
		}
		return ret;
		}

		int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
		@@ -381,6 +806,7 @@ int nbd_client_init(BlockDriverState *bs,
		qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);

		client->info.request_sizes = true;
		client->info.structured_reply = true;
		ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), export,
		tlscreds, hostname,
		&client->ioc, &client->info, errp);

block/nbd-client.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -19,6 +19,7 @@

		typedef struct {
		Coroutine *coroutine;
		uint64_t offset; /* original offset of the request */
		bool receiving; /* waiting for read_reply_co? */
		} NBDClientRequest;

include/block/nbd.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -197,6 +197,11 @@ enum {
		#define NBD_REPLY_TYPE_ERROR NBD_REPLY_ERR(1)
		#define NBD_REPLY_TYPE_ERROR_OFFSET NBD_REPLY_ERR(2)

		static inline bool nbd_reply_type_is_error(int type)
		{
		return type & (1 << 15);
		}

		/* NBD errors are based on errno numbers, so there is a 1:1 mapping,
		* but only a limited set of errno values is specified in the protocol.
		* Everything else is squashed to EINVAL.
		@@ -214,6 +219,11 @@ enum {
		struct NBDExportInfo {
		/* Set by client before nbd_receive_negotiate() */
		bool request_sizes;

		/* In-out fields, set by client before nbd_receive_negotiate() and
		* updated by server results during nbd_receive_negotiate() */
		bool structured_reply;

		/* Set by server results during nbd_receive_negotiate() */
		uint64_t size;
		uint16_t flags;
		@@ -284,4 +294,6 @@ static inline bool nbd_reply_is_structured(NBDReply *reply)
		return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
		}

		const char *nbd_reply_type_lookup(uint16_t type);

		#endif

nbd/client.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -602,9 +602,11 @@ int nbd_receive_negotiate(QIOChannel ioc, const char name,
		uint64_t magic;
		int rc;
		bool zeroes = true;
		bool structured_reply = info->structured_reply;

		trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : "<null>");

		info->structured_reply = false;
		rc = -EINVAL;

		if (outioc) {
		@@ -685,6 +687,16 @@ int nbd_receive_negotiate(QIOChannel ioc, const char name,
		if (fixedNewStyle) {
		int result;

		if (structured_reply) {
		result = nbd_request_simple_option(ioc,
		NBD_OPT_STRUCTURED_REPLY,
		errp);
		if (result < 0) {
		goto fail;
		}
		info->structured_reply = result == 1;
		}

		/* Try NBD_OPT_GO first - if it works, we are done (it
		* also gives us a good message if the server requires
		* TLS). If it is not available, fall back to

nbd/nbd-internal.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -104,7 +104,6 @@ const char *nbd_opt_lookup(uint32_t opt);
		const char *nbd_rep_lookup(uint32_t rep);
		const char *nbd_info_lookup(uint16_t info);
		const char *nbd_cmd_lookup(uint16_t info);
		const char *nbd_reply_type_lookup(uint16_t type);
		const char *nbd_err_lookup(int err);

		int nbd_drop(QIOChannel ioc, size_t size, Error *errp);