4:48 p.m.
Even though the NBD spec has been altered to allow us to accept
NBD_CMD_READ larger than the max payload size (provided our response
is a hole or broken up over more than one data chunk), we are not
planning to take advantage of that, and continue to cap NBD_CMD_READ
to 32M regardless of header size.
For NBD_CMD_WRITE_ZEROES and NBD_CMD_TRIM, the block layer already
supports 64-bit operations without any effort on our part. For
NBD_CMD_BLOCK_STATUS, the client's length is a hint; the easiest
approach for now is to truncate our answer back to 32 bits, which lets
us delay the effort of implementing NBD_REPLY_TYPE_BLOCK_STATUS_EXT to
a separate patch.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
nbd/nbd-internal.h | 7 ++-
nbd/server.c | 132 +++++++++++++++++++++++++++++++++++----------
2 files changed, 108 insertions(+), 31 deletions(-)
diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index 0016793ff4..f9fe0b6ce3 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -1,7 +1,7 @@
/*
* NBD Internal Declarations
*
- * Copyright (C) 2016-2021 Red Hat, Inc.
+ * Copyright (C) 2016-2022 Red Hat, Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
@@ -35,8 +35,11 @@
* https://github.com/yoe/nbd/blob/master/doc/proto.md
*/
-/* Size of all NBD_OPT_*, without payload */
+/* Size of all compact NBD_CMD_*, without payload */
#define NBD_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 4)
+/* Size of all extended NBD_CMD_*, without payload */
+#define NBD_EXTENDED_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 8)
+
/* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */
#define NBD_REPLY_SIZE (4 + 4 + 8)
/* Size of reply to NBD_OPT_EXPORT_NAME */
diff --git a/nbd/server.c b/nbd/server.c
index 4d1400430b..b46655b4d8 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -141,7 +141,7 @@ struct NBDClient {
uint32_t check_align; /* If non-zero, check for aligned client requests */
- bool structured_reply;
+ bool structured_reply; /* also set true if extended_headers is set */
bool extended_headers;
NBDExportMetaContexts export_meta;
@@ -1260,6 +1260,10 @@ static int nbd_negotiate_options(NBDClient *client, Error **errp)
case NBD_OPT_STRUCTURED_REPLY:
if (length) {
ret = nbd_reject_length(client, false, errp);
+ } else if (client->extended_headers) {
+ ret = nbd_negotiate_send_rep_err(
+ client, NBD_REP_ERR_EXT_HEADER_REQD, errp,
+ "extended headers already negotiated");
} else if (client->structured_reply) {
ret = nbd_negotiate_send_rep_err(
client, NBD_REP_ERR_INVALID, errp,
@@ -1276,6 +1280,19 @@ static int nbd_negotiate_options(NBDClient *client, Error **errp)
errp);
break;
+ case NBD_OPT_EXTENDED_HEADERS:
+ if (length) {
+ ret = nbd_reject_length(client, false, errp);
+ } else if (client->extended_headers) {
+ ret = nbd_negotiate_send_rep_err(
+ client, NBD_REP_ERR_INVALID, errp,
+ "extended headers already negotiated");
+ } else {
+ ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);
+ client->structured_reply = client->extended_headers = true;
+ }
+ break;
+
default:
ret = nbd_opt_drop(client, NBD_REP_ERR_UNSUP, errp,
"Unsupported option %" PRIu32 "
(%s)",
@@ -1411,11 +1428,13 @@ nbd_read_eof(NBDClient *client, void *buffer, size_t size, Error
**errp)
static int nbd_receive_request(NBDClient *client, NBDRequest *request,
Error **errp)
{
- uint8_t buf[NBD_REQUEST_SIZE];
- uint32_t magic;
+ uint8_t buf[NBD_EXTENDED_REQUEST_SIZE];
+ uint32_t magic, expect;
int ret;
+ size_t size = client->extended_headers ? NBD_EXTENDED_REQUEST_SIZE
+ : NBD_REQUEST_SIZE;
- ret = nbd_read_eof(client, buf, sizeof(buf), errp);
+ ret = nbd_read_eof(client, buf, size, errp);
if (ret < 0) {
return ret;
}
@@ -1423,13 +1442,21 @@ static int nbd_receive_request(NBDClient *client, NBDRequest
*request,
return -EIO;
}
- /* Request
- [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
- [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
- [ 6 .. 7] type (NBD_CMD_READ, ...)
- [ 8 .. 15] handle
- [16 .. 23] from
- [24 .. 27] len
+ /*
+ * Compact request
+ * [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
+ * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
+ * [ 6 .. 7] type (NBD_CMD_READ, ...)
+ * [ 8 .. 15] handle
+ * [16 .. 23] from
+ * [24 .. 27] len
+ * Extended request
+ * [ 0 .. 3] magic (NBD_EXTENDED_REQUEST_MAGIC)
+ * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, NBD_CMD_FLAG_PAYLOAD_LEN, ...)
+ * [ 6 .. 7] type (NBD_CMD_READ, ...)
+ * [ 8 .. 15] handle
+ * [16 .. 23] from
+ * [24 .. 31] len
*/
magic = ldl_be_p(buf);
@@ -1437,12 +1464,18 @@ static int nbd_receive_request(NBDClient *client, NBDRequest
*request,
request->type = lduw_be_p(buf + 6);
request->handle = ldq_be_p(buf + 8);
request->from = ldq_be_p(buf + 16);
- request->len = ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+ if (client->extended_headers) {
+ request->len = ldq_be_p(buf + 24);
+ expect = NBD_EXTENDED_REQUEST_MAGIC;
+ } else {
+ request->len = ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+ expect = NBD_REQUEST_MAGIC;
+ }
trace_nbd_receive_request(magic, request->flags, request->type,
request->from, request->len);
- if (magic != NBD_REQUEST_MAGIC) {
+ if (magic != expect) {
error_setg(errp, "invalid magic (got 0x%" PRIx32 ")",
magic);
return -EINVAL;
}
@@ -1890,14 +1923,37 @@ static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct
iovec *iov,
}
static inline void set_be_simple_reply(NBDClient *client, struct iovec *iov,
- uint64_t error, NBDRequest *request)
+ uint32_t error, NBDStructuredError *err,
+ NBDRequest *request)
{
- NBDSimpleReply *reply = iov->iov_base;
+ if (client->extended_headers) {
+ NBDExtendedReplyChunk *chunk = iov->iov_base;
- iov->iov_len = sizeof(*reply);
- stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC);
- stl_be_p(&reply->error, error);
- stq_be_p(&reply->handle, request->handle);
+ iov->iov_len = sizeof(*chunk);
+ stl_be_p(&chunk->magic, NBD_EXTENDED_REPLY_MAGIC);
+ stw_be_p(&chunk->flags, NBD_REPLY_FLAG_DONE);
+ stq_be_p(&chunk->handle, request->handle);
+ stq_be_p(&chunk->offset, request->from);
+ if (error) {
+ assert(!iov[1].iov_base);
+ iov[1].iov_base = err;
+ iov[1].iov_len = sizeof(*err);
+ stw_be_p(&chunk->type, NBD_REPLY_TYPE_ERROR);
+ stq_be_p(&chunk->length, sizeof(*err));
+ stl_be_p(&err->error, error);
+ stw_be_p(&err->message_length, 0);
+ } else {
+ stw_be_p(&chunk->type, NBD_REPLY_TYPE_NONE);
+ stq_be_p(&chunk->length, 0);
+ }
+ } else {
+ NBDSimpleReply *reply = iov->iov_base;
+
+ iov->iov_len = sizeof(*reply);
+ stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC);
+ stl_be_p(&reply->error, error);
+ stq_be_p(&reply->handle, request->handle);
+ }
}
static int nbd_co_send_simple_reply(NBDClient *client, NBDRequest *request,
@@ -1908,30 +1964,44 @@ static int nbd_co_send_simple_reply(NBDClient *client, NBDRequest
*request,
{
NBDReply hdr;
int nbd_err = system_errno_to_nbd_errno(error);
+ NBDStructuredError err;
struct iovec iov[] = {
{.iov_base = &hdr},
{.iov_base = data, .iov_len = len}
};
+ assert(!len || !nbd_err);
trace_nbd_co_send_simple_reply(request->handle, nbd_err,
nbd_err_lookup(nbd_err), len);
- set_be_simple_reply(client, &iov[0], nbd_err, request);
+ set_be_simple_reply(client, &iov[0], nbd_err, &err, request);
- return nbd_co_send_iov(client, iov, len ? 2 : 1, errp);
+ return nbd_co_send_iov(client, iov, iov[1].iov_len ? 2 : 1, errp);
}
static inline void set_be_chunk(NBDClient *client, struct iovec *iov,
uint16_t flags, uint16_t type,
NBDRequest *request, uint32_t length)
{
- NBDStructuredReplyChunk *chunk = iov->iov_base;
+ if (client->extended_headers) {
+ NBDExtendedReplyChunk *chunk = iov->iov_base;
- iov->iov_len = sizeof(*chunk);
- 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, request->handle);
- stl_be_p(&chunk->length, length);
+ iov->iov_len = sizeof(*chunk);
+ stl_be_p(&chunk->magic, NBD_EXTENDED_REPLY_MAGIC);
+ stw_be_p(&chunk->flags, flags);
+ stw_be_p(&chunk->type, type);
+ stq_be_p(&chunk->handle, request->handle);
+ stq_be_p(&chunk->offset, request->from);
+ stq_be_p(&chunk->length, length);
+ } else {
+ NBDStructuredReplyChunk *chunk = iov->iov_base;
+
+ iov->iov_len = sizeof(*chunk);
+ 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, request->handle);
+ stl_be_p(&chunk->length, length);
+ }
}
static int coroutine_fn nbd_co_send_structured_done(NBDClient *client,
@@ -2595,7 +2665,11 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
return nbd_send_generic_reply(client, request, -EINVAL,
"need non-zero length", errp);
}
- assert(request->len <= UINT32_MAX);
+ if (request->len > UINT32_MAX) {
+ /* For now, truncate our response to a 32 bit window */
+ request->len = QEMU_ALIGN_DOWN(BDRV_REQUEST_MAX_BYTES,
+ client->check_align ?: 1);
+ }
if (client->export_meta.count) {
bool dont_fragment = request->flags & NBD_CMD_FLAG_REQ_ONE;
int contexts_remaining = client->export_meta.count;
--
2.38.1