On Thu, Oct 17, 2019 at 04:27:34PM -0500, Mike Christie wrote: > nbd requires socket families to support the shutdown method so the nbd > recv workqueue can be woken up from its sock_recvmsg call. If the socket > does not support the callout we will leave recv works running or get hangs > later when the device or module is removed. > > This adds a check during socket connection/reconnection to make sure the > socket being passed in supports the needed callout. > > Reported-by: [email protected] > Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs") > Signed-off-by: Mike Christie <[email protected]>
I tested this patch to try to make sure it doesn't break typical existing use cases of the kernel NBD client using Unix and TCP servers. I used a Fedora 30 virtual machine, nbdkit-1.12.8-1.fc30, and the upstream kernel + your patch for testing. I tested it using loop-style commands similar to what I did in this talk[1] using commands from the nbdkit manual[2]. Note I did *not* test the negative case, eg. NBD over a netlink socket, as I have no easy way to test that. Anyway, I can confirm that both Unix domain sockets and TCP to localhost works fine with this patch, so: Tested-by: Richard W.M. Jones <[email protected]> Rich. [1] https://archive.fosdem.org/2019/schedule/event/nbdkit/ [2] http://libguestfs.org/nbdkit-loop.1.html > --- > drivers/block/nbd.c | 23 +++++++++++++++++++++-- > 1 file changed, 21 insertions(+), 2 deletions(-) > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index 478aa86fc1f2..7bd9e92f6bb7 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -972,6 +972,25 @@ static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx > *hctx, > return ret; > } > > +static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long > fd, > + int *err) > +{ > + struct socket *sock; > + > + *err = 0; > + sock = sockfd_lookup(fd, err); > + if (!sock) > + return NULL; > + > + if (sock->ops->shutdown == sock_no_shutdown) { > + dev_err(disk_to_dev(nbd->disk), "Unsupported socket: shutdown > callout must be supported.\n"); > + *err = -EINVAL; > + return NULL; > + } > + > + return sock; > +} > + > static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg, > bool netlink) > { > @@ -981,7 +1000,7 @@ static int nbd_add_socket(struct nbd_device *nbd, > unsigned long arg, > struct nbd_sock *nsock; > int err; > > - sock = sockfd_lookup(arg, &err); > + sock = nbd_get_socket(nbd, arg, &err); > if (!sock) > return err; > > @@ -1033,7 +1052,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, > unsigned long arg) > int i; > int err; > > - sock = sockfd_lookup(arg, &err); > + sock = nbd_get_socket(nbd, arg, &err); > if (!sock) > return err; > > -- > 2.20.1 -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org
