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/* nbd client library in userspace: state machine
* Copyright Red Hat
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* State machine for issuing commands (requests) to the server. */
STATE_MACHINE {
ISSUE_COMMAND.START:
struct command *cmd;
assert (h->cmds_to_issue != NULL);
cmd = h->cmds_to_issue;
/* Were we interrupted by reading a reply to an earlier command? If
* so, we can only get back here after a non-blocking jaunt through
* the REPLY engine, which means we are unlikely to be unblocked for
* writes yet; we want to advance back to the correct state but
* without trying a send_from_wbuf that will likely return 1.
*/
if (h->in_write_shutdown)
SET_NEXT_STATE_AND_BLOCK (%SEND_WRITE_SHUTDOWN);
else if (h->wlen) {
if (h->in_write_payload)
SET_NEXT_STATE_AND_BLOCK (%SEND_WRITE_PAYLOAD);
else
SET_NEXT_STATE_AND_BLOCK (%SEND_REQUEST);
return 0;
}
/* These fields are coincident between req.compact and req.extended */
h->req.compact.flags = htobe16 (cmd->flags);
h->req.compact.type = htobe16 (cmd->type);
h->req.compact.cookie = htobe64 (cmd->cookie);
h->req.compact.offset = htobe64 (cmd->offset);
if (h->extended_headers) {
h->req.extended.magic = htobe32 (NBD_EXTENDED_REQUEST_MAGIC);
h->req.extended.count = htobe64 (cmd->count);
h->wlen = sizeof (h->req.extended);
}
else {
assert (cmd->count <= UINT32_MAX);
h->req.compact.magic = htobe32 (NBD_REQUEST_MAGIC);
h->req.compact.count = htobe32 (cmd->count);
h->wlen = sizeof (h->req.compact);
}
h->chunks_sent++;
h->wbuf = &h->req;
if (cmd->type == NBD_CMD_WRITE || cmd->next)
h->wflags = MSG_MORE;
SET_NEXT_STATE (%SEND_REQUEST);
return 0;
ISSUE_COMMAND.SEND_REQUEST:
switch (send_from_wbuf (h)) {
case -1: SET_NEXT_STATE (%.DEAD); return 0;
case 0: SET_NEXT_STATE (%PREPARE_WRITE_PAYLOAD);
}
return 0;
ISSUE_COMMAND.PAUSE_SEND_REQUEST:
assert (h->wlen);
assert (h->cmds_to_issue != NULL);
h->in_write_payload = false;
SET_NEXT_STATE (%^REPLY.START);
return 0;
ISSUE_COMMAND.PREPARE_WRITE_PAYLOAD:
struct command *cmd;
assert (h->cmds_to_issue != NULL);
cmd = h->cmds_to_issue;
assert (cmd->cookie == be64toh (h->req.compact.cookie));
if (cmd->type == NBD_CMD_WRITE ||
(h->extended_headers && cmd->type == NBD_CMD_BLOCK_STATUS &&
cmd->flags & NBD_CMD_FLAG_PAYLOAD_LEN)) {
h->wbuf = cmd->data;
h->wlen = cmd->count;
if (cmd->next && cmd->count < 64 * 1024)
h->wflags = MSG_MORE;
SET_NEXT_STATE (%SEND_WRITE_PAYLOAD);
}
else if (cmd->type == NBD_CMD_DISC) {
h->in_write_shutdown = true;
SET_NEXT_STATE (%SEND_WRITE_SHUTDOWN);
}
else
SET_NEXT_STATE (%FINISH);
return 0;
ISSUE_COMMAND.SEND_WRITE_PAYLOAD:
switch (send_from_wbuf (h)) {
case -1: SET_NEXT_STATE (%.DEAD); return 0;
case 0: SET_NEXT_STATE (%FINISH);
}
return 0;
ISSUE_COMMAND.PAUSE_WRITE_PAYLOAD:
assert (h->wlen);
assert (h->cmds_to_issue != NULL);
h->in_write_payload = true;
SET_NEXT_STATE (%^REPLY.START);
return 0;
ISSUE_COMMAND.SEND_WRITE_SHUTDOWN:
if (h->sock->ops->shut_writes (h, h->sock))
SET_NEXT_STATE (%FINISH);
return 0;
ISSUE_COMMAND.PAUSE_WRITE_SHUTDOWN:
assert (h->in_write_shutdown);
SET_NEXT_STATE (%^REPLY.START);
return 0;
ISSUE_COMMAND.FINISH:
struct command *cmd;
assert (!h->wlen);
assert (h->cmds_to_issue != NULL);
cmd = h->cmds_to_issue;
assert (cmd->cookie == be64toh (h->req.compact.cookie));
h->cmds_to_issue = cmd->next;
if (h->cmds_to_issue_tail == cmd)
h->cmds_to_issue_tail = NULL;
cmd->next = h->cmds_in_flight;
h->cmds_in_flight = cmd;
SET_NEXT_STATE (%.READY);
return 0;
} /* END STATE MACHINE */
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