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nbd: BLOCK_STATUS for standard get_block_status function: client part

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Minimal realization: only one extent in server answer is supported.
Flag NBD_CMD_FLAG_REQ_ONE is used to force this behavior.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20180312152126.286890-6-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: grammar tweaks, fix min_block check and 32-bit cap, use -1
instead of errno on failure in nbd_negotiate_simple_meta_context,
ensure that block status makes progress on success]
Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2018-03-12 18:21:23 +03:00 • committed by Eric Blake
parent 1e98efc029
commit 78a33ab587
5 changed files with 279 additions and 0 deletions
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117
nbd/client.c
View file

@ -595,6 +595,111 @@ static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
return QIO_CHANNEL(tioc);
}
/* nbd_negotiate_simple_meta_context:
* Set one meta context. Simple means that reply must contain zero (not
* negotiated) or one (negotiated) contexts. More contexts would be considered
* as a protocol error. It's also implied that meta-data query equals queried
* context name, so, if server replies with something different then @context,
* it considered as error too.
* return 1 for successful negotiation, context_id is set
* 0 if operation is unsupported,
* -1 with errp set for any other error
*/
static int nbd_negotiate_simple_meta_context(QIOChannel *ioc,
const char *export,
const char *context,
uint32_t *context_id,
Error **errp)
{
int ret;
NBDOptionReply reply;
uint32_t received_id;
bool received;
uint32_t export_len = strlen(export);
uint32_t context_len = strlen(context);
uint32_t data_len = sizeof(export_len) + export_len +
sizeof(uint32_t) + /* number of queries */
sizeof(context_len) + context_len;
char *data = g_malloc(data_len);
char *p = data;
stl_be_p(p, export_len);
memcpy(p += sizeof(export_len), export, export_len);
stl_be_p(p += export_len, 1);
stl_be_p(p += sizeof(uint32_t), context_len);
memcpy(p += sizeof(context_len), context, context_len);
ret = nbd_send_option_request(ioc, NBD_OPT_SET_META_CONTEXT, data_len, data,
errp);
g_free(data);
if (ret < 0) {
return ret;
}
if (nbd_receive_option_reply(ioc, NBD_OPT_SET_META_CONTEXT, &reply,
errp) < 0)
{
return -1;
}
ret = nbd_handle_reply_err(ioc, &reply, errp);
if (ret <= 0) {
return ret;
}
if (reply.type == NBD_REP_META_CONTEXT) {
char *name;
size_t len;
if (nbd_read(ioc, &received_id, sizeof(received_id), errp) < 0) {
return -1;
}
be32_to_cpus(&received_id);
len = reply.length - sizeof(received_id);
name = g_malloc(len + 1);
if (nbd_read(ioc, name, len, errp) < 0) {
g_free(name);
return -1;
}
name[len] = '\0';
if (strcmp(context, name)) {
error_setg(errp, "Failed to negotiate meta context '%s', server "
"answered with different context '%s'", context,
name);
g_free(name);
return -1;
}
g_free(name);
received = true;
/* receive NBD_REP_ACK */
if (nbd_receive_option_reply(ioc, NBD_OPT_SET_META_CONTEXT, &reply,
errp) < 0)
{
return -1;
}
ret = nbd_handle_reply_err(ioc, &reply, errp);
if (ret <= 0) {
return ret;
}
}
if (reply.type != NBD_REP_ACK) {
error_setg(errp, "Unexpected reply type %" PRIx32 " expected %x",
reply.type, NBD_REP_ACK);
return -1;
}
if (received) {
*context_id = received_id;
return 1;
}
return 0;
}
int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
QCryptoTLSCreds *tlscreds, const char *hostname,
@ -606,10 +711,12 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
int rc;
bool zeroes = true;
bool structured_reply = info->structured_reply;
bool base_allocation = info->base_allocation;
trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : "<null>");
info->structured_reply = false;
info->base_allocation = false;
rc = -EINVAL;
if (outioc) {
@ -700,6 +807,16 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
info->structured_reply = result == 1;
}
if (info->structured_reply && base_allocation) {
result = nbd_negotiate_simple_meta_context(
ioc, name, "base:allocation",
&info->meta_base_allocation_id, errp);
if (result < 0) {
goto fail;
}
info->base_allocation = 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