search for: notifyread

When processing a server reply within the REPLY subgroup, we will often hit a situation where recv() requires us to block until the next NotifyRead. But since NotifyRead is the only permitted external action while in this group, we are effectively blocking CmdIssue and NotifyWrite events from happening until the server finishes the in-progress reply, even though those events have no strict dependence on the server's progress. The solution...

...0755 > --- a/generator/generator > +++ b/generator/generator > @@ -682,14 +682,14 @@ and reply_state_machine = [ > default_state with > name = "START"; > comment = "Prepare to receive a reply from the remote server"; > - external_events = [ NotifyRead, "" ]; > + external_events = []; > }; > > State { > default_state with > name = "RECV_REPLY"; > comment = "Receive a reply from the remote server"; > - external_events = [ NotifyRead, "" ]; > + externa...

Some of these affect attempts to connect to older qemu-nbd versions, some of them were triggered by manual edits to qemu-nbd source code to provoke various other compliant (if uncommon) server behaviors. Eric Blake (4): starttls: Skip error payload if falling back to unencrypted states: Reject payload to NBD_REP_ACK meta-context: Skip error payload if server lacks meta_context states: Add

...@@ and issue_command_state_machine = [ default_state with name = "SEND_REQUEST"; comment = "Sending a request to the remote server"; - external_events = [ NotifyWrite, "" ]; + external_events = [ NotifyWrite, ""; + NotifyRead, "PAUSE_SEND_REQUEST" ]; + }; + + State { + default_state with + name = "PAUSE_SEND_REQUEST"; + comment = "Interrupt send request to receive an earlier command's reply"; + external_events = []; }; State { @@ -648,7 +656,15 @@ and issue_command_...

...@@ and issue_command_state_machine = [ default_state with name = "SEND_REQUEST"; comment = "Sending a request to the remote server"; - external_events = [ NotifyWrite, "" ]; + external_events = [ NotifyWrite, ""; + NotifyRead, "PAUSE_SEND_REQUEST" ]; + }; + + State { + default_state with + name = "PAUSE_SEND_REQUEST"; + comment = "Interrupt send request to receive an earlier command's reply"; + external_events = []; }; State { @@ -648,7 +650,15 @@ and issue_command_...

...uld do all of the above in generated code. The only potential problem I can think of at the moment is the usual one with interrupts which is that second and subsequent interrupts are lost if the first interrupt hasn't been processed. However for the external events we have at the moment: | NotifyRead (* fd becomes ready to read *) | NotifyWrite (* fd becomes ready to write *) | CmdCreate (* [nbd_create] function called *) | CmdConnectSockAddr (* [nbd_aio_connect] function called *) | CmdConnectUnix (* [nbd_aio_conn...

...| 1 + 3 files changed, 71 insertions(+), 1 deletion(-) diff --git a/generator/generator b/generator/generator index 3b0ca82..deb77f0 100755 --- a/generator/generator +++ b/generator/generator @@ -771,6 +771,13 @@ and structured_reply_state_machine = [ external_events = [ NotifyRead, "" ]; }; + State { + default_state with + name = "RECV_ERROR_TAIL"; + comment = "Receive a structured reply error tail"; + external_events = [ NotifyRead, "" ]; + }; + State { default_state with name = "RECV_OFFSET_DATA&qu...

...an 256k (enough for the Linux kernel to block the server until libnbd read()s), immediately followed by nbd_aio_pwrite for a request larger than 256k (enough to block libnbd until the server read()s, but the serialized server won't read until we parse off the reply). My solution was to allow a notifyread at any time we are in the middle of writing a request, at which point we pause the current write, force the state machine to completely receive the reply, then resume where we left off writing the request. Eric Blake (3): commands: Preserve FIFO ordering states: Split ISSUE_COMMAND.SEND_REQUES...

...State { default_state with - name = "SKIP_REPLY_PAYLOAD"; - comment = "Skip newstyle NBD_OPT_STARTTLS reply payload"; + name = "RECV_REPLY_PAYLOAD"; + comment = "Receive any newstyle NBD_OPT_STARTTLS reply payload"; external_events = [ NotifyRead, "" ]; }; @@ -425,8 +425,8 @@ and newstyle_opt_structured_reply_state_machine = [ State { default_state with - name = "SKIP_REPLY_PAYLOAD"; - comment = "Skip newstyle NBD_OPT_STRUCTURED_REPLY reply payload"; + name = "RECV_REPLY_PAYLOAD"...

On 6/5/19 6:15 AM, Richard W.M. Jones wrote: > Split h->state into: > > - h->state = the state on entry to the locked region > > - h->next_state = the current state and what the "publicly visible" > state will become when we leave the locked region The rest of this thread discusses potential other names, such as h->public_state for the state visible

...diff --git a/generator/generator b/generator/generator index a289741..4c81859 100755 --- a/generator/generator +++ b/generator/generator @@ -798,6 +798,13 @@ and structured_reply_state_machine = [ comment = "Receive a structured reply block-status payload"; external_events = [ NotifyRead, "" ]; }; + + State { + default_state with + name = "FINISH"; + comment = "Finish receiving a structured reply"; + external_events = []; + }; ] (*----------------------------------------------------------------------*) diff --git a/generator/states-...

nbdkit 1.2 as a server waits for read() to see EOF, even after the client has sent NBD_CMD_DISC. That was fixed in mbdkit 1.4; and most modern NBD servers are smarter than this (they close() the write end of their traffic soon after NBD_CMD_DISC). But it's easy enough to revert nbdkit commit c70616f8 to get back to a server with the same behavior as the older nbdkit, at which point both

...comment = "Send newstyle NBD_OPT_LIST to being listing exports"; + external_events = [ NotifyWrite, "" ]; + }; + + State { + default_state with + name = "RECV_REPLY"; + comment = "Receive newstyle NBD_OPT_LIST reply"; + external_events = [ NotifyRead, "" ]; + }; + + State { + default_state with + name = "RECV_REPLY_PAYLOAD"; + comment = "Receive any newstyle NBD_OPT_LIST reply payload"; + external_events = [ NotifyRead, "" ]; + }; + + State { + default_state with + name = "CHECK...

...t; READY libnbd: debug: nbd5: nbd_pread: poll start: events=1 nbdkit: debug: starting worker thread full.2 nbdkit: debug: starting worker thread full.5 nbdkit: full.0: debug: full: pread count=512 offset=0 libnbd: debug: nbd5: nbd_pread: poll end: r=1 revents=1 libnbd: debug: nbd5: nbd_pread: event NotifyRead: READY -> REPLY.START nbdkit: libnbd: debug: nbd5: nbd_pread: transition: REPLY.START -> REPLY.RECV_REPLY debug: libnbd: debug: nbd5: nbd_pread: transition: REPLY.RECV_REPLY -> REPLY.CHECK_SIMPLE_OR_STRUCTURED_REPLY starting worker thread full.8libnbd: debug: nbd5: nbd_pread: transition: R...

Very much a work in progress as there are still many tests using qemu-io which are candidates for conversion. You'll notice at the end of test-full.sh that the new test has some duplicated code which looks as if it ought to be refactored into a Python function. When I tried to do that, I got loads of strange Python problems which may indicate bugs in nbdsh itself or problems with my

...wstyle NBD_OPT_EXTENDED_HEADERS negotiation request"; + external_events = [ NotifyWrite, "" ]; + }; + + State { + default_state with + name = "RECV_REPLY"; + comment = "Receive newstyle NBD_OPT_EXTENDED_HEADERS option reply"; + external_events = [ NotifyRead, "" ]; + }; + + State { + default_state with + name = "RECV_REPLY_PAYLOAD"; + comment = "Receive any newstyle NBD_OPT_EXTENDED_HEADERS reply payload"; + external_events = [ NotifyRead, "" ]; + }; + + State { + default_state with + name =...

...comment = "Send newstyle NBD_OPT_EXPORT_NAME export name"; + external_events = [ NotifyWrite, "" ]; + }; + + State { + default_state with + name = "RECV_REPLY"; + comment = "Receive newstyle NBD_OPT_EXPORT_NAME reply"; + external_events = [ NotifyRead, "" ]; + }; + + State { + default_state with + name = "CHECK_REPLY"; + comment = "Check newstyle NBD_OPT_EXPORT_NAME reply"; + external_events = []; + }; +] + (* Sending a command to the server. *) and issue_command_state_machine = [ State { diff --...

I'm still playing with ideas on how to split rstate from wstate (so that we can send a request without waiting for POLLIN to complete a pending reply), but this is some preliminary refactoring I found useful. I also fixed a couple of bugs while in the area (already pushed). There's a question of whether we want nbd_handle to be nearly 5k, or if we should instead keep it small and add one

...nect_socket", (1, 2); + "connect_vsock", (1, 2); + "aio_connect_vsock", (1, 2); (* These calls are proposed for a future version of libnbd, but * have not been added to any released version so far. @@ -3151,7 +3196,7 @@ end = struct let all_external_events = [NotifyRead; NotifyWrite; CmdCreate; - CmdConnectSockAddr; CmdConnectUnix; CmdConnectTCP; + CmdConnectSockAddr; CmdConnectUnix; CmdConnectVSock; CmdConnectTCP; CmdConnectCommand; CmdConnectSA; CmdConnectSocket; CmdIssue] @@ -3161,6 +3206,7 @@ let string_of_external_event = function | CmdCr...

Proposal for new APIs to list exports. The general shape of the API can probably best be seen from the examples/list-exports.c example. Rich.