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nbd: Minimal structured read for server
Minimal implementation of structured read: one structured reply chunk, no segmentation. Minimal structured error implementation: no text message. Support DF flag, but just ignore it, as there is no segmentation any way. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171027104037.8319-8-eblake@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy
Eric Blake
parent
e68c35cfb8
commit
5c54e7fa71
107
nbd/server.c
107
nbd/server.c
@ -100,6 +100,8 @@ struct NBDClient {
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QTAILQ_ENTRY(NBDClient) next;
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int nb_requests;
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bool closing;
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bool structured_reply;
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};
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/* That's all folks */
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@ -769,6 +771,23 @@ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags,
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"TLS not configured");
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}
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break;
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case NBD_OPT_STRUCTURED_REPLY:
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if (length) {
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ret = nbd_reject_length(client, length, option, false,
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errp);
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} else if (client->structured_reply) {
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ret = nbd_negotiate_send_rep_err(
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client->ioc, NBD_REP_ERR_INVALID, option, errp,
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"structured reply already negotiated");
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} else {
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ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
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option, errp);
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client->structured_reply = true;
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myflags |= NBD_FLAG_SEND_DF;
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}
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break;
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default:
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if (nbd_drop(client->ioc, length, errp) < 0) {
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return -EIO;
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@ -1243,6 +1262,60 @@ static int nbd_co_send_simple_reply(NBDClient *client,
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return nbd_co_send_iov(client, iov, len ? 2 : 1, errp);
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}
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static inline void set_be_chunk(NBDStructuredReplyChunk *chunk, uint16_t flags,
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uint16_t type, uint64_t handle, uint32_t length)
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{
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stl_be_p(&chunk->magic, NBD_STRUCTURED_REPLY_MAGIC);
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stw_be_p(&chunk->flags, flags);
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stw_be_p(&chunk->type, type);
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stq_be_p(&chunk->handle, handle);
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stl_be_p(&chunk->length, length);
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}
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static int coroutine_fn nbd_co_send_structured_read(NBDClient *client,
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uint64_t handle,
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uint64_t offset,
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void *data,
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size_t size,
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Error **errp)
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{
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NBDStructuredRead chunk;
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struct iovec iov[] = {
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{.iov_base = &chunk, .iov_len = sizeof(chunk)},
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{.iov_base = data, .iov_len = size}
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};
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trace_nbd_co_send_structured_read(handle, offset, data, size);
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set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_OFFSET_DATA,
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handle, sizeof(chunk) - sizeof(chunk.h) + size);
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stq_be_p(&chunk.offset, offset);
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return nbd_co_send_iov(client, iov, 2, errp);
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}
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static int coroutine_fn nbd_co_send_structured_error(NBDClient *client,
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uint64_t handle,
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uint32_t error,
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Error **errp)
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{
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NBDStructuredError chunk;
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int nbd_err = system_errno_to_nbd_errno(error);
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struct iovec iov[] = {
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{.iov_base = &chunk, .iov_len = sizeof(chunk)},
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/* FIXME: Support human-readable error message */
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};
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assert(nbd_err);
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trace_nbd_co_send_structured_error(handle, nbd_err,
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nbd_err_lookup(nbd_err));
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set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_ERROR, handle,
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sizeof(chunk) - sizeof(chunk.h));
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stl_be_p(&chunk.error, nbd_err);
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stw_be_p(&chunk.message_length, 0);
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return nbd_co_send_iov(client, iov, 1, errp);
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}
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/* nbd_co_receive_request
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* Collect a client request. Return 0 if request looks valid, -EIO to drop
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* connection right away, and any other negative value to report an error to
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@ -1253,6 +1326,7 @@ static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
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Error **errp)
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{
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NBDClient *client = req->client;
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int valid_flags;
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g_assert(qemu_in_coroutine());
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assert(client->recv_coroutine == qemu_coroutine_self());
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@ -1314,13 +1388,15 @@ static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
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(uint64_t)client->exp->size);
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return request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
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}
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if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
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error_setg(errp, "unsupported flags (got 0x%x)", request->flags);
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return -EINVAL;
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valid_flags = NBD_CMD_FLAG_FUA;
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if (request->type == NBD_CMD_READ && client->structured_reply) {
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valid_flags |= NBD_CMD_FLAG_DF;
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} else if (request->type == NBD_CMD_WRITE_ZEROES) {
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valid_flags |= NBD_CMD_FLAG_NO_HOLE;
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}
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if (request->type != NBD_CMD_WRITE_ZEROES &&
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(request->flags & NBD_CMD_FLAG_NO_HOLE)) {
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error_setg(errp, "unexpected flags (got 0x%x)", request->flags);
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if (request->flags & ~valid_flags) {
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error_setg(errp, "unsupported flags for command %s (got 0x%x)",
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nbd_cmd_lookup(request->type), request->flags);
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return -EINVAL;
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}
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@ -1458,10 +1534,21 @@ reply:
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local_err = NULL;
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}
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if (nbd_co_send_simple_reply(req->client, request.handle,
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ret < 0 ? -ret : 0,
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req->data, reply_data_len, &local_err) < 0)
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{
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if (client->structured_reply && request.type == NBD_CMD_READ) {
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if (ret < 0) {
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ret = nbd_co_send_structured_error(req->client, request.handle,
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-ret, &local_err);
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} else {
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ret = nbd_co_send_structured_read(req->client, request.handle,
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request.from, req->data,
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reply_data_len, &local_err);
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}
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} else {
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ret = nbd_co_send_simple_reply(req->client, request.handle,
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ret < 0 ? -ret : 0,
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req->data, reply_data_len, &local_err);
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}
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if (ret < 0) {
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error_prepend(&local_err, "Failed to send reply: ");
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goto disconnect;
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}
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@ -56,6 +56,8 @@ nbd_receive_request(uint32_t magic, uint16_t flags, uint16_t type, uint64_t from
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nbd_blk_aio_attached(const char *name, void *ctx) "Export %s: Attaching clients to AIO context %p\n"
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nbd_blk_aio_detach(const char *name, void *ctx) "Export %s: Detaching clients from AIO context %p\n"
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nbd_co_send_simple_reply(uint64_t handle, uint32_t error, const char *errname, int len) "Send simple reply: handle = %" PRIu64 ", error = %" PRIu32 " (%s), len = %d"
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nbd_co_send_structured_read(uint64_t handle, uint64_t offset, void *data, size_t size) "Send structured read data reply: handle = %" PRIu64 ", offset = %" PRIu64 ", data = %p, len = %zu"
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nbd_co_send_structured_error(uint64_t handle, int err, const char *errname) "Send structured error reply: handle = %" PRIu64 ", error = %d (%s)"
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nbd_co_receive_request_decode_type(uint64_t handle, uint16_t type, const char *name) "Decoding type: handle = %" PRIu64 ", type = %" PRIu16 " (%s)"
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nbd_co_receive_request_payload_received(uint64_t handle, uint32_t len) "Payload received: handle = %" PRIu64 ", len = %" PRIu32
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nbd_co_receive_request_cmd_write(uint32_t len) "Reading %" PRIu32 " byte(s)"
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