It's unexpected behavior that without -x option qemu-nbd do old-style negotiation. Let's use "" as a default name instead (as it is already done if tls is used) and therefore, drop old-style negotiation from Qemu NBD server. Vladimir Sementsov-Ogievskiy (2): qemu-nbd: drop old-style negotiation nbd/server: drop old-style negotiation include/block/nbd.h | 3 +-- blockdev-nbd.c | 2 +- nbd/server.c | 53 +++++++++++++-------------------------------- qemu-nbd.c | 25 +++++---------------- 4 files changed, 23 insertions(+), 60 deletions(-) -- 2.18.0
On 10/3/18 12:02 PM, Vladimir Sementsov-Ogievskiy wrote: > It's unexpected behavior that without -x option qemu-nbd do old-style > negotiation. Let's use "" as a default name instead (as it is already > done if tls is used) and therefore, drop old-style negotiation from > Qemu NBD server. Oddly enough, I wrote a similar patch in parallel, and am only now just seeing your mail. Yours is a bit stronger than mine (I added 'qemu-nbd -O' to allow explicit fallback to oldstyle, while you ripped it out altogether). The client can negotiate either style, so we don't need an option on the client side; rather, this is all about what the server should do by default. https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg00568.html Does anyone have a preference between the two? Here's the last time it was discussed: https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg03252.html > > Vladimir Sementsov-Ogievskiy (2): > qemu-nbd: drop old-style negotiation > nbd/server: drop old-style negotiation > > include/block/nbd.h | 3 +-- > blockdev-nbd.c | 2 +- > nbd/server.c | 53 +++++++++++++-------------------------------- > qemu-nbd.c | 25 +++++---------------- > 4 files changed, 23 insertions(+), 60 deletions(-) > -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
03.10.2018 20:32, Eric Blake wrote: On 10/3/18 12:02 PM, Vladimir Sementsov-Ogievskiy wrote: It's unexpected behavior that without -x option qemu-nbd do old-style negotiation. Let's use "" as a default name instead (as it is already done if tls is used) and therefore, drop old-style negotiation from Qemu NBD server. Oddly enough, I wrote a similar patch in parallel, and am only now just seeing your mail. Yours is a bit stronger than mine (I added 'qemu-nbd -O' to allow explicit fallback to oldstyle, while you ripped it out altogether). The client can negotiate either style, so we don't need an option on the client side; rather, this is all about what the server should do by default. https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg00568.html Does anyone have a preference between the two? Here's the last time it was discussed: https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg03252.html Hm, I think everyone who like new-style should answer that he don't care (except stricter way is a bit better: don't have options and code which we don't need). But if there is someone who has client which support only old-style negotiation his unhappiness (in case of strict way) will outweigh all our "bits":) I'm from the first group). But let's chose your patch Vladimir Sementsov-Ogievskiy (2): qemu-nbd: drop old-style negotiation nbd/server: drop old-style negotiation include/block/nbd.h | 3 +-- blockdev-nbd.c | 2 +- nbd/server.c | 53 +++++++++++++-------------------------------- qemu-nbd.c | 25 +++++---------------- 4 files changed, 23 insertions(+), 60 deletions(-) -- Best regards, Vladimir
On 10/3/18 12:59 PM, Vladimir Sementsov-Ogievskiy wrote: > 03.10.2018 20:32, Eric Blake wrote: > On 10/3/18 12:02 PM, Vladimir Sementsov-Ogievskiy wrote: > It's unexpected behavior that without -x option qemu-nbd do old-style > negotiation. Let's use "" as a default name instead (as it is already > done if tls is used) and therefore, drop old-style negotiation from > Qemu NBD server. Hmm, your email quoting style changed from prior emails that used to prepend '>' when quoting, making it harder to tell where the text you are quoting ends,... > > Oddly enough, I wrote a similar patch in parallel, and am only now just seeing your mail. Yours is a bit stronger than mine (I added 'qemu-nbd -O' to allow explicit fallback to oldstyle, while you ripped it out altogether). The client can negotiate either style, so we don't need an option on the client side; rather, this is all about what the server should do by default. > > https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg00568.html > > Does anyone have a preference between the two? Here's the last time it was discussed: > > https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg03252.html > and your reply begins. > Hm, I think everyone who like new-style should answer that he don't care (except stricter way is a bit better: don't have options and code which we don't need). > But if there is someone who has client which support only old-style negotiation his unhappiness (in case of strict way) will outweigh all our "bits":) > > I'm from the first group). But let's chose your patch My argument in favor of your patch over mine: nbdkit is a GREAT testbed for forcing all sorts of integration testing scenarios, including oldstyle servers. Also, it includes a plugin for translating between new and oldstyle at will. That is, if we ever legitimately encounter a client that can only talk oldstyle, but qemu only talks newstyle, we just tell the user to connect: old client => nbdkit -o nbd => newstyle qemu and then qemu doesn't have to worry about oldstyle because nbdkit does instead. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
FWIW I don't have anything to add - agree with what's been said already. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v
03.10.2018 21:08, Eric Blake wrote: > On 10/3/18 12:59 PM, Vladimir Sementsov-Ogievskiy wrote: >> 03.10.2018 20:32, Eric Blake wrote: >> On 10/3/18 12:02 PM, Vladimir Sementsov-Ogievskiy wrote: >> It's unexpected behavior that without -x option qemu-nbd do old-style >> negotiation. Let's use "" as a default name instead (as it is already >> done if tls is used) and therefore, drop old-style negotiation from >> Qemu NBD server. > > Hmm, your email quoting style changed from prior emails that used to > prepend '>' when quoting, making it harder to tell where the text you > are quoting ends,... I didn't change anything... > >> >> Oddly enough, I wrote a similar patch in parallel, and am only now >> just seeing your mail. Yours is a bit stronger than mine (I added >> 'qemu-nbd -O' to allow explicit fallback to oldstyle, while you >> ripped it out altogether). The client can negotiate either style, so >> we don't need an option on the client side; rather, this is all about >> what the server should do by default. >> >> https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg00568.html >> >> Does anyone have a preference between the two? Here's the last time >> it was discussed: >> >> https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg03252.html >> > > and your reply begins. > >> Hm, I think everyone who like new-style should answer that he don't >> care (except stricter way is a bit better: don't have options and >> code which we don't need). >> But if there is someone who has client which support only old-style >> negotiation his unhappiness (in case of strict way) will outweigh all >> our "bits":) >> >> I'm from the first group). But let's chose your patch > > My argument in favor of your patch over mine: nbdkit is a GREAT > testbed for forcing all sorts of integration testing scenarios, > including oldstyle servers. Also, it includes a plugin for > translating between new and oldstyle at will. That is, if we ever > legitimately encounter a client that can only talk oldstyle, but qemu > only talks newstyle, we just tell the user to connect: > > old client => nbdkit -o nbd => newstyle qemu > > and then qemu doesn't have to worry about oldstyle because nbdkit does > instead. > this is a bit more difficult and more overhead than option in Qemu.. But I don't sure we should care about -- Best regards, Vladimir
On Thu, Oct 04, 2018 at 12:10:17PM +0000, Vladimir Sementsov-Ogievskiy wrote: > this is a bit more difficult and more overhead than option in Qemu.. But > I don't sure we should care about I think Eric's point is that dropping oldstyle in qemu-nbd isn't really a problem because nbdkit has no plans to drop oldstyle. So there will remain a path for very old clients to keep working (whether using nbdkit natively, or using nbdkit to proxy to qemu-nbd). Eric's example used the more complex proxy case. By contrast the nbdkit native case is very simple: nbdkit -o file disk.img (where the ‘-o’ flag switches to oldstyle protocol). Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/
On 10/3/18 12:02 PM, Vladimir Sementsov-Ogievskiy wrote: > It's unexpected behavior that without -x option qemu-nbd do old-style > negotiation. Let's use "" as a default name instead (as it is already > done if tls is used) and therefore, drop old-style negotiation from > Qemu NBD server. > > Vladimir Sementsov-Ogievskiy (2): > qemu-nbd: drop old-style negotiation > nbd/server: drop old-style negotiation > > include/block/nbd.h | 3 +-- > blockdev-nbd.c | 2 +- > nbd/server.c | 53 +++++++++++++-------------------------------- > qemu-nbd.c | 25 +++++---------------- > 4 files changed, 23 insertions(+), 60 deletions(-) > Thanks; applying this series to my NBD queue. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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