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[Qemu-devel] [PATCH v6 07/12] nbd: Minimal structured read for server
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH v6 07/12] nbd: Minimal structured read for server |
Date: |
Fri, 27 Oct 2017 12:40:32 +0200 |
From: Vladimir Sementsov-Ogievskiy <address@hidden>
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 <address@hidden>
Signed-off-by: Eric Blake <address@hidden>
---
v6: only set structured_reply when replying with ack [Vladimir]
v5: correct DF flag spelling, include errname in trace, handle any bogus
payload from option
v4: better _DF flag handling, convert errno to wire format, add
comments and tracing, rework structured error for less churn when adding
text message later, don't kill connection on redundant client option
---
nbd/server.c | 107 +++++++++++++++++++++++++++++++++++++++++++++++++------
nbd/trace-events | 2 ++
2 files changed, 99 insertions(+), 10 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index a98f5622c9..5d6d9a2ddd 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -100,6 +100,8 @@ struct NBDClient {
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
+
+ bool structured_reply;
};
/* That's all folks */
@@ -768,6 +770,23 @@ static int nbd_negotiate_options(NBDClient *client,
uint16_t myflags,
"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;
@@ -1242,6 +1261,60 @@ static int nbd_co_send_simple_reply(NBDClient *client,
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
@@ -1252,6 +1325,7 @@ static int nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request,
Error **errp)
{
NBDClient *client = req->client;
+ int valid_flags;
g_assert(qemu_in_coroutine());
assert(client->recv_coroutine == qemu_coroutine_self());
@@ -1313,13 +1387,15 @@ static int nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request,
(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;
}
@@ -1457,10 +1533,21 @@ reply:
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;
}
diff --git a/nbd/trace-events b/nbd/trace-events
index ab3d7dad4f..6894f8bbb4 100644
--- a/nbd/trace-events
+++ b/nbd/trace-events
@@ -56,6 +56,8 @@ nbd_receive_request(uint32_t magic, uint16_t flags, uint16_t
type, uint64_t from
nbd_blk_aio_attached(const char *name, void *ctx) "Export %s: Attaching
clients to AIO context %p\n"
nbd_blk_aio_detach(const char *name, void *ctx) "Export %s: Detaching clients
from AIO context %p\n"
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"
+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"
+nbd_co_send_structured_error(uint64_t handle, int err, const char *errname)
"Send structured error reply: handle = %" PRIu64 ", error = %d (%s)"
nbd_co_receive_request_decode_type(uint64_t handle, uint16_t type, const char
*name) "Decoding type: handle = %" PRIu64 ", type = %" PRIu16 " (%s)"
nbd_co_receive_request_payload_received(uint64_t handle, uint32_t len)
"Payload received: handle = %" PRIu64 ", len = %" PRIu32
nbd_co_receive_request_cmd_write(uint32_t len) "Reading %" PRIu32 " byte(s)"
--
2.13.6
- [Qemu-devel] [PATCH v6 00/12] nbd minimal structured read, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 01/12] nbd: Include error names in trace messages, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 02/12] nbd: Move nbd_errno_to_system_errno() to public header, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 03/12] nbd: Expose constants and structs for structured read, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 05/12] nbd/server: Simplify nbd_negotiate_options loop, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 04/12] nbd/server: Report error for write to read-only export, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 06/12] nbd/server: Refactor zero-length option check, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 08/12] nbd/server: Include human-readable message in structured errors, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 07/12] nbd: Minimal structured read for server,
Eric Blake <=
- [Qemu-devel] [PATCH v6 09/12] nbd/client: refactor nbd_receive_starttls, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 10/12] nbd/client: prepare nbd_receive_reply for structured reply, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 11/12] nbd: Move nbd_read() to common header, Eric Blake, 2017/10/27
- [Qemu-devel] [PATCH v6 12/12] nbd: Minimal structured read for client, Eric Blake, 2017/10/27
- [Qemu-devel] [RFC PATCH v6 13/12] tweak test 83 verbosity, Eric Blake, 2017/10/27