Re: [Libguestfs] [nbdkit PATCH 3/3] RFC swab: Re-enable .extents

On Tue, Jul 07, 2020 at 05:22:47PM -0500, Eric Blake wrote: > This reverts commit 2c5aec42cf04c567639bd885cf12a57192229215. > > Now that we have an easy way to generate aligned extents from the > plugin, where the client will never see an unaligned extent > transition, it's time to put it to use. > > Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; > > --- > Here's what I used on the command line; I need to turn it into a formal test: > > $ ./nbdkit -U - eval pread='exit 1' get_size='echo 8' can_extents='exit 0' \ > extents='printf "0 3\n3 4 hole,zero\n7 1\n"' --run \ > 'qemu-img map -f raw --output=json $uri' > $ ./nbdkit -U - --filter=swab eval pread='exit 1' get_size='echo 8' can_extents='exit 0' extents='printf "0 3\n3 4 hole,zero\n7 1\n"' --run 'qemu-img map -f raw --output=json $uri'

> > except it's currently failing: > nbdkit: eval[1]: error: swab: requests to this filter must be aligned > nbdkit: backend.c:621: backend_extents: Assertion `*err' failed. > qemu-img: Could not read file metadata: Input/output error I would add -v to the command line, as it will show you exactly what requests qemu-img is making. The assert failure seems to be a separate and worrying problem.