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qemu/block/nbd-client.c
Eric Blake 75d34eb98c nbd/client: Trace server noncompliance on structured reads 
Just as we recently added a trace for a server sending block status
that doesn't match the server's advertised minimum block alignment,
let's do the same for read chunks.  But since qemu 3.1 is such a
server (because it advertised 512-byte alignment, but when serving a
file that ends in data but is not sector-aligned, NBD_CMD_READ would
detect a mid-sector change between data and hole at EOF and the
resulting read chunks are unaligned), we don't want to change our
behavior of otherwise tolerating unaligned reads.

Note that even though we fixed the server for 4.0 to advertise an
actual block alignment (which gets rid of the unaligned reads at EOF
for posix files), we can still trigger it via other means:

$ qemu-nbd --image-opts driver=blkdebug,align=512,image.driver=file,image.filename=/path/to/non-aligned-file

Arguably, that is a bug in the blkdebug block status function, for
leaking a block status that is not aligned. It may also be possible to
observe issues with a backing layer with smaller alignment than the
active layer, although so far I have been unable to write a reliable
iotest for that scenario.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190330165349.32256-1-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2019-04-01 08:58:04 -05:00

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/*
* QEMU Block driver for NBD
*
* Copyright (C) 2016 Red Hat, Inc.
* Copyright (C) 2008 Bull S.A.S.
* Author: Laurent Vivier <Laurent.Vivier@bull.net>
*
* Some parts:
* Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "trace.h"
#include "qapi/error.h"
#include "nbd-client.h"
#define HANDLE_TO_INDEX(bs, handle) ((handle) ^ (uint64_t)(intptr_t)(bs))
#define INDEX_TO_HANDLE(bs, index) ((index) ^ (uint64_t)(intptr_t)(bs))
static void nbd_recv_coroutines_wake_all(NBDClientSession *s)
{
int i;
for (i = 0; i < MAX_NBD_REQUESTS; i++) {
NBDClientRequest *req = &s->requests[i];
if (req->coroutine && req->receiving) {
aio_co_wake(req->coroutine);
}
}
}
static void nbd_teardown_connection(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
assert(client->ioc);
/* finish any pending coroutines */
qio_channel_shutdown(client->ioc,
QIO_CHANNEL_SHUTDOWN_BOTH,
NULL);
BDRV_POLL_WHILE(bs, client->connection_co);
nbd_client_detach_aio_context(bs);
object_unref(OBJECT(client->sioc));
client->sioc = NULL;
object_unref(OBJECT(client->ioc));
client->ioc = NULL;
}
static coroutine_fn void nbd_connection_entry(void *opaque)
{
NBDClientSession *s = opaque;
uint64_t i;
int ret = 0;
Error *local_err = NULL;
while (!s->quit) {
/*
* The NBD client can only really be considered idle when it has
* yielded from qio_channel_readv_all_eof(), waiting for data. This is
* the point where the additional scheduled coroutine entry happens
* after nbd_client_attach_aio_context().
*
* Therefore we keep an additional in_flight reference all the time and
* only drop it temporarily here.
*/
assert(s->reply.handle == 0);
ret = nbd_receive_reply(s->bs, s->ioc, &s->reply, &local_err);
if (local_err) {
trace_nbd_read_reply_entry_fail(ret, error_get_pretty(local_err));
error_free(local_err);
}
if (ret <= 0) {
break;
}
/* There's no need for a mutex on the receive side, because the
* handler acts as a synchronization point and ensures that only
* one coroutine is called until the reply finishes.
*/
i = HANDLE_TO_INDEX(s, s->reply.handle);
if (i >= MAX_NBD_REQUESTS ||
!s->requests[i].coroutine ||
!s->requests[i].receiving ||
(nbd_reply_is_structured(&s->reply) && !s->info.structured_reply))
{
break;
}
/* We're woken up again by the request itself. Note that there
* is no race between yielding and reentering connection_co. This
* is because:
*
* - if the request runs on the same AioContext, it is only
* entered after we yield
*
* - if the request runs on a different AioContext, reentering
* connection_co happens through a bottom half, which can only
* run after we yield.
*/
aio_co_wake(s->requests[i].coroutine);
qemu_coroutine_yield();
}
s->quit = true;
nbd_recv_coroutines_wake_all(s);
bdrv_dec_in_flight(s->bs);
s->connection_co = NULL;
aio_wait_kick();
}
static int nbd_co_send_request(BlockDriverState *bs,
NBDRequest *request,
QEMUIOVector *qiov)
{
NBDClientSession *s = nbd_get_client_session(bs);
int rc, i;
qemu_co_mutex_lock(&s->send_mutex);
while (s->in_flight == MAX_NBD_REQUESTS) {
qemu_co_queue_wait(&s->free_sema, &s->send_mutex);
}
s->in_flight++;
for (i = 0; i < MAX_NBD_REQUESTS; i++) {
if (s->requests[i].coroutine == NULL) {
break;
}
}
g_assert(qemu_in_coroutine());
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);
if (s->quit) {
rc = -EIO;
goto err;
}
assert(s->ioc);
if (qiov) {
qio_channel_set_cork(s->ioc, true);
rc = nbd_send_request(s->ioc, request);
if (rc >= 0 && !s->quit) {
if (qio_channel_writev_all(s->ioc, qiov->iov, qiov->niov,
NULL) < 0) {
rc = -EIO;
}
} else if (rc >= 0) {
rc = -EIO;
}
qio_channel_set_cork(s->ioc, false);
} else {
rc = nbd_send_request(s->ioc, request);
}
err:
if (rc < 0) {
s->quit = true;
s->requests[i].coroutine = NULL;
s->in_flight--;
qemu_co_queue_next(&s->free_sema);
}
qemu_co_mutex_unlock(&s->send_mutex);
return rc;
}
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(NBDClientSession *client,
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 (!hole_size || 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;
}
if (client->info.min_block &&
!QEMU_IS_ALIGNED(hole_size, client->info.min_block)) {
trace_nbd_structured_read_compliance("hole");
}
qemu_iovec_memset(qiov, offset - orig_offset, 0, hole_size);
return 0;
}
/* nbd_parse_blockstatus_payload
* Based on our request, we expect only one extent in reply, for the
* base:allocation context.
*/
static int nbd_parse_blockstatus_payload(NBDClientSession *client,
NBDStructuredReplyChunk *chunk,
uint8_t *payload, uint64_t orig_length,
NBDExtent *extent, Error **errp)
{
uint32_t context_id;
/* The server succeeded, so it must have sent [at least] one extent */
if (chunk->length < sizeof(context_id) + sizeof(*extent)) {
error_setg(errp, "Protocol error: invalid payload for "
"NBD_REPLY_TYPE_BLOCK_STATUS");
return -EINVAL;
}
context_id = payload_advance32(&payload);
if (client->info.context_id != context_id) {
error_setg(errp, "Protocol error: unexpected context id %d for "
"NBD_REPLY_TYPE_BLOCK_STATUS, when negotiated context "
"id is %d", context_id,
client->info.context_id);
return -EINVAL;
}
extent->length = payload_advance32(&payload);
extent->flags = payload_advance32(&payload);
if (extent->length == 0) {
error_setg(errp, "Protocol error: server sent status chunk with "
"zero length");
return -EINVAL;
}
/*
* A server sending unaligned block status is in violation of the
* protocol, but as qemu-nbd 3.1 is such a server (at least for
* POSIX files that are not a multiple of 512 bytes, since qemu
* rounds files up to 512-byte multiples but lseek(SEEK_HOLE)
* still sees an implicit hole beyond the real EOF), it's nicer to
* work around the misbehaving server. If the request included
* more than the final unaligned block, truncate it back to an
* aligned result; if the request was only the final block, round
* up to the full block and change the status to fully-allocated
* (always a safe status, even if it loses information).
*/
if (client->info.min_block && !QEMU_IS_ALIGNED(extent->length,
client->info.min_block)) {
trace_nbd_parse_blockstatus_compliance("extent length is unaligned");
if (extent->length > client->info.min_block) {
extent->length = QEMU_ALIGN_DOWN(extent->length,
client->info.min_block);
} else {
extent->length = client->info.min_block;
extent->flags = 0;
}
}
/*
* We used NBD_CMD_FLAG_REQ_ONE, so the server should not have
* sent us any more than one extent, nor should it have included
* status beyond our request in that extent. However, it's easy
* enough to ignore the server's noncompliance without killing the
* connection; just ignore trailing extents, and clamp things to
* the length of our request.
*/
if (chunk->length > sizeof(context_id) + sizeof(*extent)) {
trace_nbd_parse_blockstatus_compliance("more than one extent");
}
if (extent->length > orig_length) {
extent->length = orig_length;
trace_nbd_parse_blockstatus_compliance("extent length too large");
}
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));
/* The NBD spec requires at least one byte of payload */
if (chunk->length <= sizeof(offset)) {
error_setg(errp, "Protocol error: invalid payload for "
"NBD_REPLY_TYPE_OFFSET_DATA");
return -EINVAL;
}
if (nbd_read64(s->ioc, &offset, "OFFSET_DATA offset", errp) < 0) {
return -EIO;
}
data_size = chunk->length - sizeof(offset);
assert(data_size);
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;
}
if (s->info.min_block && !QEMU_IS_ALIGNED(data_size, s->info.min_block)) {
trace_nbd_structured_read_compliance("data");
}
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, "structured payload", 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_connection_entry. */
s->requests[i].receiving = true;
qemu_coroutine_yield();
s->requests[i].receiving = false;
if (s->quit) {
error_setg(errp, "Connection closed");
return -EIO;
}
assert(s->ioc);
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;
}
if (chunk->length) {
error_setg(errp, "Protocol error: NBD_REPLY_TYPE_NONE chunk with"
" nonzero length");
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 connection_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,
int *request_ret, QEMUIOVector *qiov, NBDReply *reply, void **payload,
Error **errp)
{
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_connection_entry */
if (reply) {
*reply = s->reply;
}
s->reply.handle = 0;
}
if (s->connection_co) {
aio_co_wake(s->connection_co);
}
return ret;
}
typedef struct NBDReplyChunkIter {
int ret;
int request_ret;
Error *err;
bool done, only_structured;
} NBDReplyChunkIter;
static void nbd_iter_channel_error(NBDReplyChunkIter *iter,
int ret, Error **local_err)
{
assert(ret < 0);
if (!iter->ret) {
iter->ret = ret;
error_propagate(&iter->err, *local_err);
} else {
error_free(*local_err);
}
*local_err = NULL;
}
static void nbd_iter_request_error(NBDReplyChunkIter *iter, int ret)
{
assert(ret < 0);
if (!iter->request_ret) {
iter->request_ret = ret;
}
}
/* 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, request_ret;
NBDReply local_reply;
NBDStructuredReplyChunk *chunk;
Error *local_err = NULL;
if (s->quit) {
error_setg(&local_err, "Connection closed");
nbd_iter_channel_error(iter, -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,
&request_ret, qiov, reply, payload,
&local_err);
if (ret < 0) {
nbd_iter_channel_error(iter, ret, &local_err);
} else if (request_ret < 0) {
nbd_iter_request_error(iter, request_ret);
}
/* Do not execute the body of NBD_FOREACH_REPLY_CHUNK for simple reply. */
if (nbd_reply_is_simple(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 false;
}
static int nbd_co_receive_return_code(NBDClientSession *s, uint64_t handle,
int *request_ret, Error **errp)
{
NBDReplyChunkIter iter;
NBD_FOREACH_REPLY_CHUNK(s, iter, handle, false, NULL, NULL, NULL) {
/* nbd_reply_chunk_iter_receive does all the work */
}
error_propagate(errp, iter.err);
*request_ret = iter.request_ret;
return iter.ret;
}
static int nbd_co_receive_cmdread_reply(NBDClientSession *s, uint64_t handle,
uint64_t offset, QEMUIOVector *qiov,
int *request_ret, 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(s, &reply.structured, payload,
offset, qiov, &local_err);
if (ret < 0) {
s->quit = true;
nbd_iter_channel_error(&iter, 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_channel_error(&iter, -EINVAL, &local_err);
}
}
g_free(payload);
payload = NULL;
}
error_propagate(errp, iter.err);
*request_ret = iter.request_ret;
return iter.ret;
}
static int nbd_co_receive_blockstatus_reply(NBDClientSession *s,
uint64_t handle, uint64_t length,
NBDExtent *extent,
int *request_ret, Error **errp)
{
NBDReplyChunkIter iter;
NBDReply reply;
void *payload = NULL;
Error *local_err = NULL;
bool received = false;
assert(!extent->length);
NBD_FOREACH_REPLY_CHUNK(s, iter, handle, false, NULL, &reply, &payload) {
int ret;
NBDStructuredReplyChunk *chunk = &reply.structured;
assert(nbd_reply_is_structured(&reply));
switch (chunk->type) {
case NBD_REPLY_TYPE_BLOCK_STATUS:
if (received) {
s->quit = true;
error_setg(&local_err, "Several BLOCK_STATUS chunks in reply");
nbd_iter_channel_error(&iter, -EINVAL, &local_err);
}
received = true;
ret = nbd_parse_blockstatus_payload(s, &reply.structured,
payload, length, extent,
&local_err);
if (ret < 0) {
s->quit = true;
nbd_iter_channel_error(&iter, ret, &local_err);
}
break;
default:
if (!nbd_reply_type_is_error(chunk->type)) {
s->quit = true;
error_setg(&local_err,
"Unexpected reply type: %d (%s) "
"for CMD_BLOCK_STATUS",
chunk->type, nbd_reply_type_lookup(chunk->type));
nbd_iter_channel_error(&iter, -EINVAL, &local_err);
}
}
g_free(payload);
payload = NULL;
}
if (!extent->length && !iter.request_ret) {
error_setg(&local_err, "Server did not reply with any status extents");
nbd_iter_channel_error(&iter, -EIO, &local_err);
}
error_propagate(errp, iter.err);
*request_ret = iter.request_ret;
return iter.ret;
}
static int nbd_co_request(BlockDriverState *bs, NBDRequest *request,
QEMUIOVector *write_qiov)
{
int ret, request_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;
}
ret = nbd_co_receive_return_code(client, request->handle,
&request_ret, &local_err);
if (local_err) {
trace_nbd_co_request_fail(request->from, request->len, request->handle,
request->flags, request->type,
nbd_cmd_lookup(request->type),
ret, error_get_pretty(local_err));
error_free(local_err);
}
return ret ? ret : request_ret;
}
int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags)
{
int ret, request_ret;
Error *local_err = NULL;
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_READ,
.from = offset,
.len = bytes,
};
assert(bytes <= NBD_MAX_BUFFER_SIZE);
assert(!flags);
if (!bytes) {
return 0;
}
/*
* Work around the fact that the block layer doesn't do
* byte-accurate sizing yet - if the read exceeds the server's
* advertised size because the block layer rounded size up, then
* truncate the request to the server and tail-pad with zero.
*/
if (offset >= client->info.size) {
assert(bytes < BDRV_SECTOR_SIZE);
qemu_iovec_memset(qiov, 0, 0, bytes);
return 0;
}
if (offset + bytes > client->info.size) {
uint64_t slop = offset + bytes - client->info.size;
assert(slop < BDRV_SECTOR_SIZE);
qemu_iovec_memset(qiov, bytes - slop, 0, slop);
request.len -= slop;
}
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
return ret;
}
ret = nbd_co_receive_cmdread_reply(client, request.handle, offset, qiov,
&request_ret, &local_err);
if (local_err) {
trace_nbd_co_request_fail(request.from, request.len, request.handle,
request.flags, request.type,
nbd_cmd_lookup(request.type),
ret, error_get_pretty(local_err));
error_free(local_err);
}
return ret ? ret : request_ret;
}
int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_WRITE,
.from = offset,
.len = bytes,
};
assert(!(client->info.flags & NBD_FLAG_READ_ONLY));
if (flags & BDRV_REQ_FUA) {
assert(client->info.flags & NBD_FLAG_SEND_FUA);
request.flags |= NBD_CMD_FLAG_FUA;
}
assert(bytes <= NBD_MAX_BUFFER_SIZE);
if (!bytes) {
return 0;
}
return nbd_co_request(bs, &request, qiov);
}
int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
int bytes, BdrvRequestFlags flags)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_WRITE_ZEROES,
.from = offset,
.len = bytes,
};
assert(!(client->info.flags & NBD_FLAG_READ_ONLY));
if (!(client->info.flags & NBD_FLAG_SEND_WRITE_ZEROES)) {
return -ENOTSUP;
}
if (flags & BDRV_REQ_FUA) {
assert(client->info.flags & NBD_FLAG_SEND_FUA);
request.flags |= NBD_CMD_FLAG_FUA;
}
if (!(flags & BDRV_REQ_MAY_UNMAP)) {
request.flags |= NBD_CMD_FLAG_NO_HOLE;
}
if (!bytes) {
return 0;
}
return nbd_co_request(bs, &request, NULL);
}
int nbd_client_co_flush(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = { .type = NBD_CMD_FLUSH };
if (!(client->info.flags & NBD_FLAG_SEND_FLUSH)) {
return 0;
}
request.from = 0;
request.len = 0;
return nbd_co_request(bs, &request, NULL);
}
int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = {
.type = NBD_CMD_TRIM,
.from = offset,
.len = bytes,
};
assert(!(client->info.flags & NBD_FLAG_READ_ONLY));
if (!(client->info.flags & NBD_FLAG_SEND_TRIM) || !bytes) {
return 0;
}
return nbd_co_request(bs, &request, NULL);
}
int coroutine_fn nbd_client_co_block_status(BlockDriverState *bs,
bool want_zero,
int64_t offset, int64_t bytes,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
int ret, request_ret;
NBDExtent extent = { 0 };
NBDClientSession *client = nbd_get_client_session(bs);
Error *local_err = NULL;
NBDRequest request = {
.type = NBD_CMD_BLOCK_STATUS,
.from = offset,
.len = MIN(MIN_NON_ZERO(QEMU_ALIGN_DOWN(INT_MAX,
bs->bl.request_alignment),
client->info.max_block),
MIN(bytes, client->info.size - offset)),
.flags = NBD_CMD_FLAG_REQ_ONE,
};
if (!client->info.base_allocation) {
*pnum = bytes;
*map = offset;
*file = bs;
return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
}
/*
* Work around the fact that the block layer doesn't do
* byte-accurate sizing yet - if the status request exceeds the
* server's advertised size because the block layer rounded size
* up, we truncated the request to the server (above), or are
* called on just the hole.
*/
if (offset >= client->info.size) {
*pnum = bytes;
assert(bytes < BDRV_SECTOR_SIZE);
/* Intentionally don't report offset_valid for the hole */
return BDRV_BLOCK_ZERO;
}
if (client->info.min_block) {
assert(QEMU_IS_ALIGNED(request.len, client->info.min_block));
}
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
return ret;
}
ret = nbd_co_receive_blockstatus_reply(client, request.handle, bytes,
&extent, &request_ret, &local_err);
if (local_err) {
trace_nbd_co_request_fail(request.from, request.len, request.handle,
request.flags, request.type,
nbd_cmd_lookup(request.type),
ret, error_get_pretty(local_err));
error_free(local_err);
}
if (ret < 0 || request_ret < 0) {
return ret ? ret : request_ret;
}
assert(extent.length);
*pnum = extent.length;
*map = offset;
*file = bs;
return (extent.flags & NBD_STATE_HOLE ? 0 : BDRV_BLOCK_DATA) |
(extent.flags & NBD_STATE_ZERO ? BDRV_BLOCK_ZERO : 0) |
BDRV_BLOCK_OFFSET_VALID;
}
void nbd_client_detach_aio_context(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
qio_channel_detach_aio_context(QIO_CHANNEL(client->ioc));
}
static void nbd_client_attach_aio_context_bh(void *opaque)
{
BlockDriverState *bs = opaque;
NBDClientSession *client = nbd_get_client_session(bs);
/* The node is still drained, so we know the coroutine has yielded in
* nbd_read_eof(), the only place where bs->in_flight can reach 0, or it is
* entered for the first time. Both places are safe for entering the
* coroutine.*/
qemu_aio_coroutine_enter(bs->aio_context, client->connection_co);
bdrv_dec_in_flight(bs);
}
void nbd_client_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
NBDClientSession *client = nbd_get_client_session(bs);
qio_channel_attach_aio_context(QIO_CHANNEL(client->ioc), new_context);
bdrv_inc_in_flight(bs);
/* Need to wait here for the BH to run because the BH must run while the
* node is still drained. */
aio_wait_bh_oneshot(new_context, nbd_client_attach_aio_context_bh, bs);
}
void nbd_client_close(BlockDriverState *bs)
{
NBDClientSession *client = nbd_get_client_session(bs);
NBDRequest request = { .type = NBD_CMD_DISC };
assert(client->ioc);
nbd_send_request(client->ioc, &request);
nbd_teardown_connection(bs);
}
static QIOChannelSocket *nbd_establish_connection(SocketAddress *saddr,
Error **errp)
{
QIOChannelSocket *sioc;
Error *local_err = NULL;
sioc = qio_channel_socket_new();
qio_channel_set_name(QIO_CHANNEL(sioc), "nbd-client");
qio_channel_socket_connect_sync(sioc, saddr, &local_err);
if (local_err) {
object_unref(OBJECT(sioc));
error_propagate(errp, local_err);
return NULL;
}
qio_channel_set_delay(QIO_CHANNEL(sioc), false);
return sioc;
}
static int nbd_client_connect(BlockDriverState *bs,
SocketAddress *saddr,
const char *export,
QCryptoTLSCreds *tlscreds,
const char *hostname,
const char *x_dirty_bitmap,
Error **errp)
{
NBDClientSession *client = nbd_get_client_session(bs);
int ret;
/*
* establish TCP connection, return error if it fails
* TODO: Configurable retry-until-timeout behaviour.
*/
QIOChannelSocket *sioc = nbd_establish_connection(saddr, errp);
if (!sioc) {
return -ECONNREFUSED;
}
/* NBD handshake */
logout("session init %s\n", export);
qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);
client->info.request_sizes = true;
client->info.structured_reply = true;
client->info.base_allocation = true;
client->info.x_dirty_bitmap = g_strdup(x_dirty_bitmap);
client->info.name = g_strdup(export ?: "");
ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), tlscreds, hostname,
&client->ioc, &client->info, errp);
g_free(client->info.x_dirty_bitmap);
g_free(client->info.name);
if (ret < 0) {
logout("Failed to negotiate with the NBD server\n");
object_unref(OBJECT(sioc));
return ret;
}
if (x_dirty_bitmap && !client->info.base_allocation) {
error_setg(errp, "requested x-dirty-bitmap %s not found",
x_dirty_bitmap);
ret = -EINVAL;
goto fail;
}
if (client->info.flags & NBD_FLAG_READ_ONLY) {
ret = bdrv_apply_auto_read_only(bs, "NBD export is read-only", errp);
if (ret < 0) {
goto fail;
}
}
if (client->info.flags & NBD_FLAG_SEND_FUA) {
bs->supported_write_flags = BDRV_REQ_FUA;
bs->supported_zero_flags |= BDRV_REQ_FUA;
}
if (client->info.flags & NBD_FLAG_SEND_WRITE_ZEROES) {
bs->supported_zero_flags |= BDRV_REQ_MAY_UNMAP;
}
client->sioc = sioc;
if (!client->ioc) {
client->ioc = QIO_CHANNEL(sioc);
object_ref(OBJECT(client->ioc));
}
/* Now that we're connected, set the socket to be non-blocking and
* kick the reply mechanism. */
qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
client->connection_co = qemu_coroutine_create(nbd_connection_entry, client);
bdrv_inc_in_flight(bs);
nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs));
logout("Established connection with NBD server\n");
return 0;
fail:
/*
* We have connected, but must fail for other reasons. The
* connection is still blocking; send NBD_CMD_DISC as a courtesy
* to the server.
*/
{
NBDRequest request = { .type = NBD_CMD_DISC };
nbd_send_request(client->ioc ?: QIO_CHANNEL(sioc), &request);
object_unref(OBJECT(sioc));
return ret;
}
}
int nbd_client_init(BlockDriverState *bs,
SocketAddress *saddr,
const char *export,
QCryptoTLSCreds *tlscreds,
const char *hostname,
const char *x_dirty_bitmap,
Error **errp)
{
NBDClientSession *client = nbd_get_client_session(bs);
client->bs = bs;
qemu_co_mutex_init(&client->send_mutex);
qemu_co_queue_init(&client->free_sema);
return nbd_client_connect(bs, saddr, export, tlscreds, hostname,
x_dirty_bitmap, errp);
}
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