Re: [Libguestfs] nbdkit Assertion `h->can_flush == 1' failed on Arch
On 3/16/20 3:39 AM, Richard W.M. Jones wrote:
https://aur.archlinux.org/packages/nbdkit/#comment-733981 reports that
tests-parallel-nbd.sh hangs. Looking at the log file from the test
reveals:
nbdkit: backend.c:523: backend_flush: Assertion `h->can_flush == 1' failed.
I can confirm the hang.
I've attached the full log. If you want to see other logs from the
run (probably not relevant) then download
https://svenne.dk/nbdkit-20200315/nbdkit-logs-20200315.tar.gz
I believe the assertion comes from calling flush when can_flush
previously returned false, but also I don't quite understand why the
server is doing this.
However I think the wider problem is that the reporter is using the
non-libnbd "standalone" nbd plugin. I basically never test this any
longer. I wonder if we should think about either having a way to
routinely test it despite libnbd being installed, or simply dropping
it?
My plan is to patch the bug, backport the patch to the stable branches,
and then remove the file for the next major release. libnbd is now
stable enough that I'm comfortable enough having nbdkit 1.20 depend on
libnbd (and only the stable releases, like 1.18.2, will still have the
option of building a limited nbd plugin without libnbd).
I will ask the reporter if they can try installing libnbd.
Rich.
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Eric Blake, Principal Software Engineer
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