On Thu, 27 Jun 2013 18:20:37 -0400 Paul Clements <paul.cleme...@us.sios.com>
wrote:
> > --- a/drivers/block/nbd.c
> > > +++ b/drivers/block/nbd.c
> > > @@ -623,6 +623,8 @@ static int __nbd_ioctl(struct block_device *bdev,
> > struct nbd_device *nbd,
> > > if (!nbd->sock)
> > > return -EINVAL;
> > >
> > > + nbd->disconnect = 1;
> > > +
> > > nbd_send_req(nbd, &sreq);
> > > return 0;
> > > }
> > > @@ -654,6 +656,7 @@ static int __nbd_ioctl(struct block_device *bdev,
> > struct nbd_device *nbd,
> > > nbd->sock = SOCKET_I(inode);
> > > if (max_part > 0)
> > > bdev->bd_invalidated = 1;
> > > + nbd->disconnect = 0; /* we're connected
> > now */
> > > return 0;
> > > } else {
> > > fput(file);
> > > @@ -742,6 +745,8 @@ static int __nbd_ioctl(struct block_device *bdev,
> > struct nbd_device *nbd,
> > > set_capacity(nbd->disk, 0);
> > > if (max_part > 0)
> > > ioctl_by_bdev(bdev, BLKRRPART, 0);
> > > + if (nbd->disconnect) /* user requested, ignore socket
> > errors */
> > > + return 0;
> > > return nbd->harderror;
> > > }
> >
> > hm, how does nbd work... Hard to tell as nothing seems to be documented
> > anywhere :(
> >
>
> I think most people look at the nbd-client to see. :)
>
> But I will work on some docs for the ioctls...
>
> Briefly, though, it goes something like this:
>
> nbd-client and nbd-server negotiate parameters, including the server
> telling the client how big the export is
>
> Then the nbd-client does a series of ioctls to set up the device:
>
> NBD_SET_SIZE - set the size of the device
> NBD_SET_SOCK - tell the kernel which socket to use
> NBD_DO_IT - this ioctl lasts for the life of the device and causes
> nbd-client to go into a receive loop, handling I/O replies from the
> nbd-server
>
> NBD_DISCONNECT, meanwhile, can be called from a separate thread (usually
> "nbd-client -d" calls it). This requests a disconnect of the device.
OK, but. "Would it be safer to clear ->disconnect in NBD_DO_IT?"
If not safer, would it be cleaner?
> > The cool kids are using bool lately ;)
> >
>
> Hey, maybe I want to be able to compile with gcc 2.7.2 ? :)
Sob, I miss 2.7.2. It was a good 50% faster than the new improved
models. But I don't think this yearning makes us cool.
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