On 06/26/2013 06:21:07 PM, Andrew Morton wrote: > On Wed, 19 Jun 2013 17:09:18 -0400 (EDT) Paul Clements > <[email protected]> wrote: > > > Currently, when a disconnect is requested by the user (via > NBD_DISCONNECT > > ioctl) the return from NBD_DO_IT is undefined (it is usually one of > > several error codes). This means that nbd-client does not know if a > > manual disconnect was performed or whether a network error occurred. > > Because of this, nbd-client's persist mode (which tries to > reconnect after > > error, but not after manual disconnect) does not always work > correctly. > > > > This change fixes this by causing NBD_DO_IT to always return 0 if a > user > > requests a disconnect. This means that nbd-client can correctly > either > > persist the connection (if an error occurred) or disconnect (if the > user > > requested it). > > This sounds like something which users of 3.10 and earlier kernels > might want, so I added the Cc:stable tag. Please let me know if > you disagree. > > > --- 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 wrote the busybox version, which might be a bit simpler: http://git.busybox.net/busybox/tree/networking/nbd-client.c (Sorry about the #ifdefs, they're not mine.) > afacit the code assumes that the user will run ioctl(NBD_DISCONNECT) > and > then ioctl(NBD_DO_IT) and then ioctl(NBD_SET_SOCK), yes? Does this > change mean that if userspace calls the ioctls in an > other-than-expected order, Weird Things will happen? Would it be > safer > to clear ->disconnect in NBD_DO_IT? > > --- a/include/linux/nbd.h > > +++ b/include/linux/nbd.h > > @@ -41,6 +41,7 @@ struct nbd_device { > > u64 bytesize; > > pid_t pid; /* pid of nbd-client, if attached */ > > int xmit_timeout; > > + int disconnect; /* a disconnect has been requested by user */ > > }; > > The cool kids are using bool lately ;) No, they're not. The C++ guys and stuffy old ex-cobol types are, and think it helps. (Does any architecture anywhere _not_ use int for bool?) Rob ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Nbd-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nbd-general
