search for: 3f2b729

....c @@ -118,7 +118,10 @@ else conn->cmds_done = cmd; - SET_NEXT_STATE (%.READY); + if (conn->cmds_to_issue) + SET_NEXT_STATE (%^ISSUE_COMMAND.START); + else + SET_NEXT_STATE (%.READY); return 0; } /* END STATE MACHINE */ diff --git a/lib/internal.h b/lib/internal.h index 3f2b729..466af9d 100644 --- a/lib/internal.h +++ b/lib/internal.h @@ -182,6 +182,7 @@ struct nbd_connection { * acknowledge them. */ struct command_in_flight *cmds_to_issue, *cmds_in_flight, *cmds_done; + bool in_write_payload; }; struct meta_context { -- 2.20.1

...his a * problem? Probably it isn't. If it is, we could add a flag to * the command struct to tell SEND_REQUEST not to add it to the * in-flight list. */ - return nbd_internal_run (conn->h, conn, cmd_issue); + return 0; } diff --git a/lib/internal.h b/lib/internal.h index 3f2b729..67bd52a 100644 --- a/lib/internal.h +++ b/lib/internal.h @@ -265,6 +265,12 @@ extern void nbd_internal_set_last_error (int errnum, char *error); extern int nbd_internal_errno_of_nbd_error (uint32_t error); extern const char *nbd_internal_name_of_nbd_cmd (uint16_t type); +/* rw.c */ +extern stru...

This might not be the final solution, but it certainly seems to solve a deadlock for me that I could trigger by using 'nbdkit --filter=noparallel memory 512k' and calling nbd_aio_pread for a request larger than 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

Patch 1/6 was posted before and I didn't change it: https://www.redhat.com/archives/libguestfs/2019-May/thread.html#00134 That doesn't necessarily mean I shouldn't change it, I'm posting it again because the other patches depend on it. The main change in this series is we add three new API functions: nbd_aio_is_created - connection has just been created

On v1, we discussed whether cmds_to_issue needed to be a list, since it never had more than one element. I played with the idea of making it a list, and allowing the client to queue up new commands regardless of whether the state machine is currently in READY. I also polished up the tmp demo into a bit more full-fledged example file, worth including since it also let me discover a hard-to-hit race