Re: [Libguestfs] [PATCH nbdkit 3/8] server: Implement Block Status requests to read allocation status.

This commit implements the core NBD protocol for the "base:allocation" Block Status replies. --- server/internal.h | 7 ++ server/protocol.h | 15 +++ server/protocol-handshake-newstyle.c | 81 ++++++++++++++- server/protocol.c | 141 ++++++++++++++++++++++++--- 4 files changed, 229 insertions(+), 15 deletions(-)

+static int +send_structured_reply_block_status (struct connection *conn, + uint64_t handle, + uint16_t cmd, uint16_t flags, + uint32_t count, uint64_t offset, + struct nbdkit_extents *extents) +{ + ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&conn->write_lock); + struct structured_reply reply; + size_t nr_extents = nbdkit_extents_size (extents); + uint32_t context_id; + size_t i; + int r; + + assert (cmd == NBD_CMD_BLOCK_STATUS); +

+ + /* Send each block descriptor. */ + for (i = 0; i < nr_extents; ++i) {

+ const struct nbdkit_extent e = nbdkit_get_extent (extents, i); + struct block_descriptor bd; + + if (i == 0) + assert (e.offset == offset); + + bd.length = htobe32 (e.length); + bd.status_flags = htobe32 (e.type & 3); + + r = conn->send (conn, &bd, sizeof bd); + if (r == -1) { + nbdkit_error ("write reply: %s: %m", name_of_nbd_cmd (cmd)); + return connection_set_status (conn, -1); + } + }

@@ -498,15 +605,23 @@ protocol_recv_request_send_reply (struct connection *conn) } /* Currently we prefer to send simple replies for everything except - * where we have to (ie. NBD_CMD_READ when structured_replies have - * been negotiated). However this prevents us from sending - * human-readable error messages to the client, so we should - * reconsider this in future. + * where we have to (ie. NBD_CMD_READ and NBD_CMD_BLOCK_STATUS when + * structured_replies have been negotiated). However this prevents + * us from sending human-readable error messages to the client, so + * we should reconsider this in future. */ - if (conn->structured_replies && cmd == NBD_CMD_READ) { - if (!error) - return send_structured_reply_read (conn, request.handle, cmd, - buf, count, offset); + if (conn->structured_replies && + (cmd == NBD_CMD_READ || cmd == NBD_CMD_BLOCK_STATUS)) { + if (!error) { + if (cmd == NBD_CMD_READ) + return send_structured_reply_read (conn, request.handle, cmd, + buf, count, offset); + else /* NBD_CMD_BLOCK_STATUS */ + return send_structured_reply_block_status (conn, request.handle, + cmd, flags, + count, offset, + extents); + } else return send_structured_reply_error (conn, request.handle, cmd, error);