Message ID | 20181003171947.588103-1-eblake@redhat.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | nbd: Flip qemu-nbd to prefer newstyle; add -O for old behavior | expand |
On 10/3/18 12:19 PM, Eric Blake wrote: > Oldstyle NBD negotiation cannot perform any of the extensions that > we have recently been relying on. While you can always pass -x "" > to get newstyle negotiation, these days, it is better to just default > to newstyle (with an empty export name) and fall back to oldstyle > only on an explicit request. > > For comparison: > > nbdkit 1.3 switched its default to newstyle (Jan 2018): > https://github.com/libguestfs/nbdkit/commit/b2a8aecc > https://github.com/libguestfs/nbdkit/commit/8158e773 > > nbd 3.10 dropped oldstyle long ago (Mar 2015): > https://github.com/NetworkBlockDevice/nbd/commit/36940193 Oh, I should also add: qemu as client can manage either style since 2.6.0, commit 69b49502d8 > +++ b/qemu-nbd.c > @@ -86,6 +86,7 @@ static void usage(const char *name) > " -v, --verbose display extra debugging information\n" > " -x, --export-name=NAME expose export by name\n" > " -D, --description=TEXT with -x, also export a human-readable description\n" > +" -O, --oldstyle force oldstyle negotiation\n" and maybe I should touch up the -x and -D wording, to at least mention that -x defaults to "" without -O.
03.10.2018 20:19, Eric Blake wrote: > Oldstyle NBD negotiation cannot perform any of the extensions that > we have recently been relying on. While you can always pass -x "" > to get newstyle negotiation, these days, it is better to just default > to newstyle (with an empty export name) and fall back to oldstyle > only on an explicit request. > > For comparison: > > nbdkit 1.3 switched its default to newstyle (Jan 2018): > https://github.com/libguestfs/nbdkit/commit/b2a8aecc > https://github.com/libguestfs/nbdkit/commit/8158e773 > > nbd 3.10 dropped oldstyle long ago (Mar 2015): > https://github.com/NetworkBlockDevice/nbd/commit/36940193 > > Signed-off-by: Eric Blake <eblake@redhat.com> > --- > qemu-nbd.c | 27 +++++++++++++++++++-------- > 1 file changed, 19 insertions(+), 8 deletions(-) > > diff --git a/qemu-nbd.c b/qemu-nbd.c > index 51b9d38c727..8571a4f93d8 100644 > --- a/qemu-nbd.c > +++ b/qemu-nbd.c > @@ -86,6 +86,7 @@ static void usage(const char *name) > " -v, --verbose display extra debugging information\n" > " -x, --export-name=NAME expose export by name\n" > " -D, --description=TEXT with -x, also export a human-readable description\n" If we prefer this way, -x and -D descriptions should be updated a bit, like in my patch > +" -O, --oldstyle force oldstyle negotiation\n" > "\n" > "Exposing part of the image:\n" > " -o, --offset=OFFSET offset into the image\n" > @@ -529,6 +530,7 @@ int main(int argc, char **argv) > { "object", required_argument, NULL, QEMU_NBD_OPT_OBJECT }, > { "export-name", required_argument, NULL, 'x' }, > { "description", required_argument, NULL, 'D' }, > + { "oldstyle", no_argument, NULL, 'O' }, > { "tls-creds", required_argument, NULL, QEMU_NBD_OPT_TLSCREDS }, > { "image-opts", no_argument, NULL, QEMU_NBD_OPT_IMAGE_OPTS }, > { "trace", required_argument, NULL, 'T' }, > @@ -551,6 +553,7 @@ int main(int argc, char **argv) > QDict *options = NULL; > const char *export_name = NULL; > const char *export_description = NULL; > + bool oldstyle = false; > const char *tlscredsid = NULL; > bool imageOpts = false; > bool writethrough = true; > @@ -723,6 +726,9 @@ int main(int argc, char **argv) > case 'D': > export_description = optarg; > break; > + case 'O': > + oldstyle = true; > + break; > case 'v': > verbose = 1; > break; > @@ -799,7 +805,16 @@ int main(int argc, char **argv) > } > } > > + if (!oldstyle && !export_name) { > + /* Set the default NBD protocol export name, to favor new style. */ > + export_name = ""; > + } > + > if (tlscredsid) { > + if (oldstyle) { > + error_report("TLS is incompatible with oldstyle"); > + exit(EXIT_FAILURE); > + } > if (sockpath) { > error_report("TLS is only supported with IPv4/IPv6"); > exit(EXIT_FAILURE); > @@ -808,11 +823,6 @@ int main(int argc, char **argv) > error_report("TLS is not supported with a host device"); > exit(EXIT_FAILURE); > } > - if (!export_name) { > - /* Set the default NBD protocol export name, since > - * we *must* use new style protocol for TLS */ > - export_name = ""; > - } > tlscreds = nbd_get_tls_creds(tlscredsid, &local_err); > if (local_err) { > error_report("Failed to get TLS creds %s", > @@ -1013,13 +1023,14 @@ int main(int argc, char **argv) > error_report_err(local_err); > exit(EXIT_FAILURE); > } > + if (oldstyle && (export_name || export_description)) { > + error_report("oldstyle negotiation cannot set export details"); > + exit(EXIT_FAILURE); > + } > if (export_name) { > nbd_export_set_name(exp, export_name); > nbd_export_set_description(exp, export_description); > newproto = true; a bit strange, to have both newproto and oldstyle variables which are opposite by value. > - } else if (export_description) { > - error_report("Export description requires an export name"); > - exit(EXIT_FAILURE); > } > > if (device) {
On 10/3/18 12:38 PM, Vladimir Sementsov-Ogievskiy wrote: > 03.10.2018 20:19, Eric Blake wrote: >> Oldstyle NBD negotiation cannot perform any of the extensions that >> we have recently been relying on. While you can always pass -x "" >> to get newstyle negotiation, these days, it is better to just default >> to newstyle (with an empty export name) and fall back to oldstyle >> only on an explicit request. >> >> + if (oldstyle && (export_name || export_description)) { >> + error_report("oldstyle negotiation cannot set export details"); >> + exit(EXIT_FAILURE); >> + } >> if (export_name) { >> nbd_export_set_name(exp, export_name); >> nbd_export_set_description(exp, export_description); >> newproto = true; > > a bit strange, to have both newproto and oldstyle variables which are > opposite by value. Yeah. I added a function-local 'oldstyle' before noticing that there was a file static 'newproto'. We could squash this in: diff --git i/qemu-nbd.c w/qemu-nbd.c index 8571a4f93d8..2b0f7de86d0 100644 --- i/qemu-nbd.c +++ w/qemu-nbd.c @@ -56,7 +56,7 @@ #define MBR_SIZE 512 static NBDExport *exp; -static bool newproto; +static bool oldstyle; static int verbose; static char *srcpath; static SocketAddress *saddr; @@ -355,7 +355,7 @@ static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc, nb_fds++; nbd_update_server_watch(); - nbd_client_new(newproto ? NULL : exp, cioc, + nbd_client_new(oldstyle ? exp : NULL, cioc, tlscreds, NULL, nbd_client_closed); } @@ -553,7 +553,6 @@ int main(int argc, char **argv) QDict *options = NULL; const char *export_name = NULL; const char *export_description = NULL; - bool oldstyle = false; const char *tlscredsid = NULL; bool imageOpts = false; bool writethrough = true; @@ -1030,7 +1029,6 @@ int main(int argc, char **argv) if (export_name) { nbd_export_set_name(exp, export_name); nbd_export_set_description(exp, export_description); - newproto = true; } if (device) {
diff --git a/qemu-nbd.c b/qemu-nbd.c index 51b9d38c727..8571a4f93d8 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -86,6 +86,7 @@ static void usage(const char *name) " -v, --verbose display extra debugging information\n" " -x, --export-name=NAME expose export by name\n" " -D, --description=TEXT with -x, also export a human-readable description\n" +" -O, --oldstyle force oldstyle negotiation\n" "\n" "Exposing part of the image:\n" " -o, --offset=OFFSET offset into the image\n" @@ -529,6 +530,7 @@ int main(int argc, char **argv) { "object", required_argument, NULL, QEMU_NBD_OPT_OBJECT }, { "export-name", required_argument, NULL, 'x' }, { "description", required_argument, NULL, 'D' }, + { "oldstyle", no_argument, NULL, 'O' }, { "tls-creds", required_argument, NULL, QEMU_NBD_OPT_TLSCREDS }, { "image-opts", no_argument, NULL, QEMU_NBD_OPT_IMAGE_OPTS }, { "trace", required_argument, NULL, 'T' }, @@ -551,6 +553,7 @@ int main(int argc, char **argv) QDict *options = NULL; const char *export_name = NULL; const char *export_description = NULL; + bool oldstyle = false; const char *tlscredsid = NULL; bool imageOpts = false; bool writethrough = true; @@ -723,6 +726,9 @@ int main(int argc, char **argv) case 'D': export_description = optarg; break; + case 'O': + oldstyle = true; + break; case 'v': verbose = 1; break; @@ -799,7 +805,16 @@ int main(int argc, char **argv) } } + if (!oldstyle && !export_name) { + /* Set the default NBD protocol export name, to favor new style. */ + export_name = ""; + } + if (tlscredsid) { + if (oldstyle) { + error_report("TLS is incompatible with oldstyle"); + exit(EXIT_FAILURE); + } if (sockpath) { error_report("TLS is only supported with IPv4/IPv6"); exit(EXIT_FAILURE); @@ -808,11 +823,6 @@ int main(int argc, char **argv) error_report("TLS is not supported with a host device"); exit(EXIT_FAILURE); } - if (!export_name) { - /* Set the default NBD protocol export name, since - * we *must* use new style protocol for TLS */ - export_name = ""; - } tlscreds = nbd_get_tls_creds(tlscredsid, &local_err); if (local_err) { error_report("Failed to get TLS creds %s", @@ -1013,13 +1023,14 @@ int main(int argc, char **argv) error_report_err(local_err); exit(EXIT_FAILURE); } + if (oldstyle && (export_name || export_description)) { + error_report("oldstyle negotiation cannot set export details"); + exit(EXIT_FAILURE); + } if (export_name) { nbd_export_set_name(exp, export_name); nbd_export_set_description(exp, export_description); newproto = true; - } else if (export_description) { - error_report("Export description requires an export name"); - exit(EXIT_FAILURE); } if (device) {
Oldstyle NBD negotiation cannot perform any of the extensions that we have recently been relying on. While you can always pass -x "" to get newstyle negotiation, these days, it is better to just default to newstyle (with an empty export name) and fall back to oldstyle only on an explicit request. For comparison: nbdkit 1.3 switched its default to newstyle (Jan 2018): https://github.com/libguestfs/nbdkit/commit/b2a8aecc https://github.com/libguestfs/nbdkit/commit/8158e773 nbd 3.10 dropped oldstyle long ago (Mar 2015): https://github.com/NetworkBlockDevice/nbd/commit/36940193 Signed-off-by: Eric Blake <eblake@redhat.com> --- qemu-nbd.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-)