[Libguestfs] nbdkit error: "write reply: NBD_CMD_WRITE: Broken pipe"

[Richard W.M. Jones]

On Fri, May 06, 2022 at 02:08:25PM +0100, Nikolaus Rath wrote:
> On May 03 2022, rjones at redhat.com (Richard W.M. Jones) wrote:
> >> So I tried to reproduce this, and noticed something odd. It seems I can
> >> disconnect the nbd device (nbd-client -d) while there are still requests
> >> in flight:
> >> 
> >> May 02 15:20:50 vostro.rath.org kernel: nbd1: detected capacity change from 0 to 52428800
> >> May 02 15:20:50 vostro.rath.org kernel: block nbd1: NBD_DISCONNECT
> >> May 02 15:20:50 vostro.rath.org kernel: block nbd1: Disconnected due to user request.
> >> May 02 15:20:50 vostro.rath.org kernel: block nbd1: shutting down sockets
> >> May 02 15:20:50 vostro.rath.org kernel: I/O error, dev nbd1, sector 776 op 0x0:(READ)
> >> flags 0x80700 phys_seg 29 prio class 0
> >> May 02 15:20:50 vostro.rath.org kernel: I/O error, dev nbd1, sector 776 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
> >> May 02 15:20:50 vostro.rath.org kernel: Buffer I/O error on dev nbd1, logical block 97, async page read
> >> May 02 15:20:50 vostro.rath.org kernel: block nbd1: Attempted send on invalid socket
> >> May 02 15:20:50 vostro.rath.org kernel: I/O error, dev nbd1, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0
> >> May 02 15:20:50 vostro.rath.org kernel: block nbd1: Attempted send on invalid socket
> >> May 02 15:20:50 vostro.rath.org kernel: I/O error, dev nbd1, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0
> >> 
> >> This was generated by running:
> >> 
> >> $ nbd-client localhost /dev/nbd1 && mkfs.ext4 /dev/nbd1 && nbd-client -d
> >> /dev/nbd1
> >> 
> >> Is that expected behavior?
> >
> > It's a bit unexpected to me.  Adding Wouter to the thread - he might
> > have an idea here, especially if there's a way to have "nbd-client -d"
> > wait for pending requests to finish before disconnecting.
> >
> > I don't use the kernel client very much myself.  We mostly use either
> > libnbd or the qemu client.
> 
> Did you Cc Wouter to your email? I didn't see a Cc header, but perhaps
> this was stripped by the mailing list software?
> 
> Or is there a more appropriate list where I could follow-up on this? 

I did.  You could also try the nbd general mailing list:

https://lists.debian.org/nbd/

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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