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

[Nikolaus Rath]

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? 

Thanks!
-Nikolaus
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