Quoting Eric Blake (2017-11-17 09:05:55) > The NBD spec says that a server may fail any transmission request > with ESHUTDOWN when it is apparent that no further request from > the client can be successfully honored. The client is supposed > to then initiate a soft shutdown (wait for all remaining in-flight > requests to be answered, then send NBD_CMD_DISC). However, since > qemu's server never uses ESHUTDOWN errors, this code was mostly > untested since its introduction in commit b6f5d3b5. > > More recently, I learned that nbdkit as the NBD server is able to > send ESHUTDOWN errors, so I finally tested this code, and noticed > that our client was special-casing ESHUTDOWN to cause a hard > shutdown (immediate disconnect, with no NBD_CMD_DISC), but only > if the server sends this error as a simple reply. Further > investigation found that commit d2febedb introduced a regression > where structured replies behave differently than simple replies - > but that the structured reply behavior is more in line with the > spec (even if we still lack code in nbd-client.c to properly quit > sending further requests). So this patch reverts the portion of > b6f5d3b5 that introduced an improper hard-disconnect special-case > at the lower level, and leaves the future enhancement of a nicer > soft-disconnect at the higher level for another day. > > CC: qemu-sta...@nongnu.org
Since 2.10.x lacks d2febedb, the patch would look something like: diff --git a/nbd/client.c b/nbd/client.c index 4caff77119..f04e95542f 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -945,12 +945,6 @@ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp) reply->handle = ldq_be_p(buf + 8); reply->error = nbd_errno_to_system_errno(reply->error); - - if (reply->error == ESHUTDOWN) { - /* This works even on mingw which lacks a native ESHUTDOWN */ - error_setg(errp, "server shutting down"); - return -EINVAL; - } trace_nbd_receive_reply(magic, reply->error, reply->handle); if (magic != NBD_REPLY_MAGIC) { If that seems reasonable I can apply it as such. > Signed-off-by: Eric Blake <ebl...@redhat.com> > Message-Id: <20171113194857.13933-1-ebl...@redhat.com> > Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > --- > nbd/client.c | 6 ------ > 1 file changed, 6 deletions(-) > > diff --git a/nbd/client.c b/nbd/client.c > index 4e15fc484d..eea236ca06 100644 > --- a/nbd/client.c > +++ b/nbd/client.c > @@ -996,15 +996,9 @@ int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, > Error **errp) > if (ret < 0) { > break; > } > - > trace_nbd_receive_simple_reply(reply->simple.error, > nbd_err_lookup(reply->simple.error), > reply->handle); > - if (reply->simple.error == NBD_ESHUTDOWN) { > - /* This works even on mingw which lacks a native ESHUTDOWN */ > - error_setg(errp, "server shutting down"); > - return -EINVAL; > - } > break; > case NBD_STRUCTURED_REPLY_MAGIC: > ret = nbd_receive_structured_reply_chunk(ioc, &reply->structured, > errp); > -- > 2.13.6 > >