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>
diff --git a/nbd/server.c b/nbd/server.c
index cf81560..3261fd1 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -100,6 +100,8 @@
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
+
+ bool structured_reply;
};
/* That's all folks */
@@ -769,6 +771,23 @@
"TLS not configured");
}
break;
+
+ case NBD_OPT_STRUCTURED_REPLY:
+ if (length) {
+ ret = nbd_reject_length(client, length, option, false,
+ errp);
+ } else if (client->structured_reply) {
+ ret = nbd_negotiate_send_rep_err(
+ client->ioc, NBD_REP_ERR_INVALID, option, errp,
+ "structured reply already negotiated");
+ } else {
+ ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
+ option, errp);
+ client->structured_reply = true;
+ myflags |= NBD_FLAG_SEND_DF;
+ }
+ break;
+
default:
if (nbd_drop(client->ioc, length, errp) < 0) {
return -EIO;
@@ -1243,6 +1262,60 @@
return nbd_co_send_iov(client, iov, len ? 2 : 1, errp);
}
+static inline void set_be_chunk(NBDStructuredReplyChunk *chunk, uint16_t flags,
+ uint16_t type, uint64_t handle, uint32_t length)
+{
+ stl_be_p(&chunk->magic, NBD_STRUCTURED_REPLY_MAGIC);
+ stw_be_p(&chunk->flags, flags);
+ stw_be_p(&chunk->type, type);
+ stq_be_p(&chunk->handle, handle);
+ stl_be_p(&chunk->length, length);
+}
+
+static int coroutine_fn nbd_co_send_structured_read(NBDClient *client,
+ uint64_t handle,
+ uint64_t offset,
+ void *data,
+ size_t size,
+ Error **errp)
+{
+ NBDStructuredRead chunk;
+ struct iovec iov[] = {
+ {.iov_base = &chunk, .iov_len = sizeof(chunk)},
+ {.iov_base = data, .iov_len = size}
+ };
+
+ trace_nbd_co_send_structured_read(handle, offset, data, size);
+ set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_OFFSET_DATA,
+ handle, sizeof(chunk) - sizeof(chunk.h) + size);
+ stq_be_p(&chunk.offset, offset);
+
+ return nbd_co_send_iov(client, iov, 2, errp);
+}
+
+static int coroutine_fn nbd_co_send_structured_error(NBDClient *client,
+ uint64_t handle,
+ uint32_t error,
+ Error **errp)
+{
+ NBDStructuredError chunk;
+ int nbd_err = system_errno_to_nbd_errno(error);
+ struct iovec iov[] = {
+ {.iov_base = &chunk, .iov_len = sizeof(chunk)},
+ /* FIXME: Support human-readable error message */
+ };
+
+ assert(nbd_err);
+ trace_nbd_co_send_structured_error(handle, nbd_err,
+ nbd_err_lookup(nbd_err));
+ set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_ERROR, handle,
+ sizeof(chunk) - sizeof(chunk.h));
+ stl_be_p(&chunk.error, nbd_err);
+ stw_be_p(&chunk.message_length, 0);
+
+ return nbd_co_send_iov(client, iov, 1, errp);
+}
+
/* nbd_co_receive_request
* Collect a client request. Return 0 if request looks valid, -EIO to drop
* connection right away, and any other negative value to report an error to
@@ -1253,6 +1326,7 @@
Error **errp)
{
NBDClient *client = req->client;
+ int valid_flags;
g_assert(qemu_in_coroutine());
assert(client->recv_coroutine == qemu_coroutine_self());
@@ -1314,13 +1388,15 @@
(uint64_t)client->exp->size);
return request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
}
- if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
- error_setg(errp, "unsupported flags (got 0x%x)", request->flags);
- return -EINVAL;
+ valid_flags = NBD_CMD_FLAG_FUA;
+ if (request->type == NBD_CMD_READ && client->structured_reply) {
+ valid_flags |= NBD_CMD_FLAG_DF;
+ } else if (request->type == NBD_CMD_WRITE_ZEROES) {
+ valid_flags |= NBD_CMD_FLAG_NO_HOLE;
}
- if (request->type != NBD_CMD_WRITE_ZEROES &&
- (request->flags & NBD_CMD_FLAG_NO_HOLE)) {
- error_setg(errp, "unexpected flags (got 0x%x)", request->flags);
+ if (request->flags & ~valid_flags) {
+ error_setg(errp, "unsupported flags for command %s (got 0x%x)",
+ nbd_cmd_lookup(request->type), request->flags);
return -EINVAL;
}
@@ -1458,10 +1534,21 @@
local_err = NULL;
}
- if (nbd_co_send_simple_reply(req->client, request.handle,
- ret < 0 ? -ret : 0,
- req->data, reply_data_len, &local_err) < 0)
- {
+ if (client->structured_reply && request.type == NBD_CMD_READ) {
+ if (ret < 0) {
+ ret = nbd_co_send_structured_error(req->client, request.handle,
+ -ret, &local_err);
+ } else {
+ ret = nbd_co_send_structured_read(req->client, request.handle,
+ request.from, req->data,
+ reply_data_len, &local_err);
+ }
+ } else {
+ ret = nbd_co_send_simple_reply(req->client, request.handle,
+ ret < 0 ? -ret : 0,
+ req->data, reply_data_len, &local_err);
+ }
+ if (ret < 0) {
error_prepend(&local_err, "Failed to send reply: ");
goto disconnect;
}
