Hi Josef, The pastebin has expired the link, and I can't access your patch. Seems to default to 1 day deletion. Could you please create a new paste or send the patch inline in this email thread? I am more than happy to try the patch out. Thank you for your analysis. Matthew On Sat, Apr 23, 2022 at 3:24 AM Josef Bacik <josef@xxxxxxxxxxxxxx> wrote: > > On Fri, Apr 22, 2022 at 1:42 AM Matthew Ruffell > <matthew.ruffell@xxxxxxxxxxxxx> wrote: > > > > Dear maintainers of the nbd subsystem, > > > > A user has come across an issue which causes the nbd module to hang after a > > disconnect where a write has been made to a qemu qcow image file, with qemu-nbd > > being the server. > > > > Ok there's two problems here, but I want to make sure I have the right > fix for the hang first. Can you apply this patch > > https://paste.centos.org/view/b1a2d01a > > and make sure the hang goes away? Once that part is fixed I'll fix > the IO errors, this is just us racing with systemd while we teardown > the device and then we're triggering a partition read while the device > is going down and it's complaining loudly. Before we would > set_capacity to 0 whenever we disconnected, but that causes problems > with file systems that may still have the device open. However now we > only do this if the server does the CLEAR_SOCK ioctl, which clearly > can race with systemd poking the device, so I need to make it > set_capacity(0) when the last opener closes the device to prevent this > style of race. > > Let me know if that patch fixes the hang, and then I'll work up > something for the capacity problem. Thanks, > > Josef
