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nbd: Minimal structured read for client

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Minimal implementation: for structured error only error_report error
message.

Note that test 83 is now more verbose, because the implementation
prints more warnings about unexpected communication errors; perhaps
future patches should tone things down by using trace messages
instead of traces, but the common case of successful communication
is no noisier than before.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171027104037.8319-13-eblake@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2017-10-27 12:40:37 +02:00 committed by Eric Blake
parent 56dc682bf5
commit f140e30003
6 changed files with 502 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

498
block/nbd-client.c
View File

@ -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 {
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;
}
}
/* Tell the read handler to read another header. */
s->reply.handle = 0;
error_setg(errp, "Connection closed");
return -EIO;
}
s->requests[i].coroutine = NULL;
assert(s->reply.handle == handle);
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;
}
return qio_channel_readv_all(s->ioc, qiov->iov, qiov->niov,
errp) < 0 ? -EIO : 0;
}
/* 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)
{
NBDClientSession *client = nbd_get_client_session(bs);
int ret;
NBDReplyChunkIter iter;
if (qiov) {
assert(request->type == NBD_CMD_WRITE || request->type == NBD_CMD_READ);
assert(request->len == iov_size(qiov->iov, qiov->niov));
} else {
assert(request->type != NBD_CMD_WRITE && request->type != NBD_CMD_READ);
NBD_FOREACH_REPLY_CHUNK(s, iter, handle, false, NULL, NULL, NULL) {
/* nbd_reply_chunk_iter_receive does all the work */
}
ret = nbd_co_send_request(bs, request,
request->type == NBD_CMD_WRITE ? qiov : NULL);
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)
{
int ret;
NBDStructuredReplyChunk *chunk = &reply.structured;
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);
}
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);

1
block/nbd-client.h
View File

@ -19,6 +19,7 @@
typedef struct {
Coroutine *coroutine;
uint64_t offset; /* original offset of the request */
bool receiving; /* waiting for read_reply_co? */
} NBDClientRequest;

12
include/block/nbd.h
View File

@ -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

12
nbd/client.c
View File

@ -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

1
nbd/nbd-internal.h
View File

@ -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);

15
tests/qemu-iotests/083.out
View File

@ -41,6 +41,7 @@ can't open device nbd+tcp://127.0.0.1:PORT/foo
=== Check disconnect after neg2 ===
Connection closed
read failed: Input/output error
=== Check disconnect 8 neg2 ===
@ -53,32 +54,39 @@ can't open device nbd+tcp://127.0.0.1:PORT/foo
=== Check disconnect before request ===
Connection closed
read failed: Input/output error
=== Check disconnect after request ===
Connection closed
read failed: Input/output error
=== Check disconnect before reply ===
Connection closed
read failed: Input/output error
=== Check disconnect after reply ===
Unexpected end-of-file before all bytes were read
read failed: Input/output error
=== Check disconnect 4 reply ===
Unexpected end-of-file before all bytes were read
Connection closed
read failed: Input/output error
=== Check disconnect 8 reply ===
Unexpected end-of-file before all bytes were read
Connection closed
read failed: Input/output error
=== Check disconnect before data ===
Unexpected end-of-file before all bytes were read
read failed: Input/output error
=== Check disconnect after data ===
@ -108,6 +116,7 @@ can't open device nbd+tcp://127.0.0.1:PORT/
=== Check disconnect after neg-classic ===
Connection closed
read failed: Input/output error
=== Check disconnect before neg1 ===
@ -168,28 +177,34 @@ read failed: Input/output error
=== Check disconnect after request ===
Connection closed
read failed: Input/output error
=== Check disconnect before reply ===
Connection closed
read failed: Input/output error
=== Check disconnect after reply ===
Unexpected end-of-file before all bytes were read
read failed: Input/output error
=== Check disconnect 4 reply ===
Unexpected end-of-file before all bytes were read
Connection closed
read failed: Input/output error
=== Check disconnect 8 reply ===
Unexpected end-of-file before all bytes were read
Connection closed
read failed: Input/output error
=== Check disconnect before data ===
Unexpected end-of-file before all bytes were read
read failed: Input/output error
=== Check disconnect after data ===