qemu/nbd/trace-events
Eric Blake a7c8ed36bf nbd/server: Prepare for alternate-size headers
Upstream NBD now documents[1] an extension that supports 64-bit effect
lengths in requests.  As part of that extension, the size of the reply
headers will change in order to permit a 64-bit length in the reply
for symmetry[2].  Additionally, where the reply header is currently 16
bytes for simple reply, and 20 bytes for structured reply; with the
extension enabled, there will only be one extended reply header, of 32
bytes, with both structured and extended modes sending identical
payloads for chunked replies.

Since we are already wired up to use iovecs, it is easiest to allow
for this change in header size by splitting each structured reply
across multiple iovecs, one for the header (which will become wider in
a future patch according to client negotiation), and the other(s) for
the chunk payload, and removing the header from the payload struct
definitions.  Rename the affected functions with s/structured/chunk/
to make it obvious that the code will be reused in extended mode.

Interestingly, the client side code never utilized the packed types,
so only the server code needs to be updated.

[1] https://github.com/NetworkBlockDevice/nbd/blob/extension-ext-header/doc/proto.md
as of NBD commit e6f3b94a934

[2] Note that on the surface, this is because some future server might
permit a 4G+ NBD_CMD_READ and need to reply with that much data in one
transaction.  But even though the extended reply length is widened to
64 bits, for now the NBD spec is clear that servers will not reply
with more than a maximum payload bounded by the 32-bit
NBD_INFO_BLOCK_SIZE field; allowing a client and server to mutually
agree to transactions larger than 4G would require yet another
extension.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230608135653.2918540-4-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
2023-07-19 15:25:27 -05:00

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# See docs/devel/tracing.rst for syntax documentation.
# client.c
nbd_send_option_request(uint32_t opt, const char *name, uint32_t len) "Sending option request %" PRIu32" (%s), len %" PRIu32
nbd_receive_option_reply(uint32_t option, const char *optname, uint32_t type, const char *typename, uint32_t length) "Received option reply %" PRIu32" (%s), type %" PRIu32" (%s), len %" PRIu32
nbd_server_error_msg(uint32_t err, const char *type, const char *msg) "server reported error 0x%" PRIx32 " (%s) with additional message: %s"
nbd_reply_err_ignored(uint32_t option, const char *name, uint32_t reply, const char *reply_name) "server failed request %" PRIu32 " (%s) with error 0x%" PRIx32 " (%s), attempting fallback"
nbd_receive_list(const char *name, const char *desc) "export list includes '%s', description '%s'"
nbd_opt_info_go_start(const char *opt, const char *name) "Attempting %s for export '%s'"
nbd_opt_info_go_success(const char *opt) "Export is ready after %s request"
nbd_opt_info_unknown(int info, const char *name) "Ignoring unknown info %d (%s)"
nbd_opt_info_block_size(uint32_t minimum, uint32_t preferred, uint32_t maximum) "Block sizes are 0x%" PRIx32 ", 0x%" PRIx32 ", 0x%" PRIx32
nbd_receive_query_exports_start(const char *wantname) "Querying export list for '%s'"
nbd_receive_query_exports_success(const char *wantname) "Found desired export name '%s'"
nbd_receive_starttls_new_client(void) "Setting up TLS"
nbd_receive_starttls_tls_handshake(void) "Starting TLS handshake"
nbd_opt_meta_request(const char *optname, const char *context, const char *export) "Requesting %s %s for export %s"
nbd_opt_meta_reply(const char *optname, const char *context, uint32_t id) "Received %s mapping of %s to id %" PRIu32
nbd_start_negotiate(void *tlscreds, const char *hostname) "Receiving negotiation tlscreds=%p hostname=%s"
nbd_receive_negotiate_magic(uint64_t magic) "Magic is 0x%" PRIx64
nbd_receive_negotiate_server_flags(uint32_t globalflags) "Global flags are 0x%" PRIx32
nbd_receive_negotiate_name(const char *name) "Requesting NBD export name '%s'"
nbd_receive_negotiate_size_flags(uint64_t size, uint16_t flags) "Size is %" PRIu64 ", export flags 0x%" PRIx16
nbd_init_set_socket(void) "Setting NBD socket"
nbd_init_set_block_size(unsigned long block_size) "Setting block size to %lu"
nbd_init_set_size(unsigned long sectors) "Setting size to %lu block(s)"
nbd_init_trailing_bytes(int ignored_bytes) "Ignoring trailing %d bytes of export"
nbd_init_set_readonly(void) "Setting readonly attribute"
nbd_init_finish(void) "Negotiation ended"
nbd_client_loop(void) "Doing NBD loop"
nbd_client_loop_ret(int ret, const char *error) "NBD loop returned %d: %s"
nbd_client_clear_queue(void) "Clearing NBD queue"
nbd_client_clear_socket(void) "Clearing NBD socket"
nbd_send_request(uint64_t from, uint32_t len, uint64_t handle, uint16_t flags, uint16_t type, const char *name) "Sending request to server: { .from = %" PRIu64", .len = %" PRIu32 ", .handle = %" PRIu64 ", .flags = 0x%" PRIx16 ", .type = %" PRIu16 " (%s) }"
nbd_receive_simple_reply(int32_t error, const char *errname, uint64_t handle) "Got simple reply: { .error = %" PRId32 " (%s), handle = %" PRIu64" }"
nbd_receive_structured_reply_chunk(uint16_t flags, uint16_t type, const char *name, uint64_t handle, uint32_t length) "Got structured reply chunk: { flags = 0x%" PRIx16 ", type = %d (%s), handle = %" PRIu64 ", length = %" PRIu32 " }"
# common.c
nbd_unknown_error(int err) "Squashing unexpected error %d to EINVAL"
# server.c
nbd_negotiate_send_rep_len(uint32_t opt, const char *optname, uint32_t type, const char *typename, uint32_t len) "Reply opt=%" PRIu32 " (%s), type=%" PRIu32 " (%s), len=%" PRIu32
nbd_negotiate_send_rep_err(const char *msg) "sending error message \"%s\""
nbd_negotiate_send_rep_list(const char *name, const char *desc) "Advertising export name '%s' description '%s'"
nbd_negotiate_handle_export_name(void) "Checking length"
nbd_negotiate_handle_export_name_request(const char *name) "Client requested export '%s'"
nbd_negotiate_send_info(int info, const char *name, uint32_t length) "Sending NBD_REP_INFO type %d (%s) with remaining length %" PRIu32
nbd_negotiate_handle_info_requests(int requests) "Client requested %d items of info"
nbd_negotiate_handle_info_request(int request, const char *name) "Client requested info %d (%s)"
nbd_negotiate_handle_info_block_size(uint32_t minimum, uint32_t preferred, uint32_t maximum) "advertising minimum 0x%" PRIx32 ", preferred 0x%" PRIx32 ", maximum 0x%" PRIx32
nbd_negotiate_handle_starttls(void) "Setting up TLS"
nbd_negotiate_handle_starttls_handshake(void) "Starting TLS handshake"
nbd_negotiate_meta_context(const char *optname, const char *export, uint32_t queries) "Client requested %s for export %s, with %" PRIu32 " queries"
nbd_negotiate_meta_query_skip(const char *reason) "Skipping meta query: %s"
nbd_negotiate_meta_query_parse(const char *query) "Parsed meta query '%s'"
nbd_negotiate_meta_query_reply(const char *context, uint32_t id) "Replying with meta context '%s' id %" PRIu32
nbd_negotiate_options_flags(uint32_t flags) "Received client flags 0x%" PRIx32
nbd_negotiate_options_check_magic(uint64_t magic) "Checking opts magic 0x%" PRIx64
nbd_negotiate_options_check_option(uint32_t option, const char *name) "Checking option %" PRIu32 " (%s)"
nbd_negotiate_begin(void) "Beginning negotiation"
nbd_negotiate_new_style_size_flags(uint64_t size, unsigned flags) "advertising size %" PRIu64 " and flags 0x%x"
nbd_negotiate_success(void) "Negotiation succeeded"
nbd_receive_request(uint32_t magic, uint16_t flags, uint16_t type, uint64_t from, uint32_t len) "Got request: { magic = 0x%" PRIx32 ", .flags = 0x%" PRIx16 ", .type = 0x%" PRIx16 ", from = %" PRIu64 ", len = %" PRIu32 " }"
nbd_blk_aio_attached(const char *name, void *ctx) "Export %s: Attaching clients to AIO context %p"
nbd_blk_aio_detach(const char *name, void *ctx) "Export %s: Detaching clients from AIO context %p"
nbd_co_send_simple_reply(uint64_t handle, uint32_t error, const char *errname, int len) "Send simple reply: handle = %" PRIu64 ", error = %" PRIu32 " (%s), len = %d"
nbd_co_send_chunk_done(uint64_t handle) "Send structured reply done: handle = %" PRIu64
nbd_co_send_chunk_read(uint64_t handle, uint64_t offset, void *data, size_t size) "Send structured read data reply: handle = %" PRIu64 ", offset = %" PRIu64 ", data = %p, len = %zu"
nbd_co_send_chunk_read_hole(uint64_t handle, uint64_t offset, size_t size) "Send structured read hole reply: handle = %" PRIu64 ", offset = %" PRIu64 ", len = %zu"
nbd_co_send_extents(uint64_t handle, unsigned int extents, uint32_t id, uint64_t length, int last) "Send block status reply: handle = %" PRIu64 ", extents = %u, context = %d (extents cover %" PRIu64 " bytes, last chunk = %d)"
nbd_co_send_chunk_error(uint64_t handle, int err, const char *errname, const char *msg) "Send structured error reply: handle = %" PRIu64 ", error = %d (%s), msg = '%s'"
nbd_co_receive_request_decode_type(uint64_t handle, uint16_t type, const char *name) "Decoding type: handle = %" PRIu64 ", type = %" PRIu16 " (%s)"
nbd_co_receive_request_payload_received(uint64_t handle, uint32_t len) "Payload received: handle = %" PRIu64 ", len = %" PRIu32
nbd_co_receive_align_compliance(const char *op, uint64_t from, uint32_t len, uint32_t align) "client sent non-compliant unaligned %s request: from=0x%" PRIx64 ", len=0x%" PRIx32 ", align=0x%" PRIx32
nbd_trip(void) "Reading request"
# client-connection.c
nbd_connect_thread_sleep(uint64_t timeout) "timeout %" PRIu64