Re: [Libguestfs] [nbdkit PATCH] tests: Check that cache-min-block-size works properly

On Wed, Aug 04, 2021 at 05:08:32PM +0200, Martin Kletzander wrote: > Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; > --- > tests/test-cache-block-size.sh | 33 ++++++++++++++++++++++----------- > 1 file changed, 22 insertions(+), 11 deletions(-) > > diff --git a/tests/test-cache-block-size.sh b/tests/test-cache-block-size.sh > index d20cc94002b6..5e83ebc1cfaa 100755 > --- a/tests/test-cache-block-size.sh > +++ b/tests/test-cache-block-size.sh > @@ -47,24 +47,35 @@ truncate -s 128K cache-block-size.img > > # Run nbdkit with the caching filter. > start_nbdkit -P cache-block-size.pid -U $sock --filter=cache \ > - file cache-block-size.img cache-min-block-size=4K > + file cache-block-size.img cache-min-block-size=64K \ Because of commit c1905b0a2 ("cache, cow: Use a 64K block size by default"), 64K is the default block size. So this doesn't test that the parameter works. Maybe choose a different block size here?

Rest of it is fine, so ACK, but better if the block size above was changed. Rich. > + cache-on-read=true > > nbdsh --connect "nbd+unix://?socket=$sock" \ > -c ' > -# Write some pattern data to the overlay and check it reads back OK. > -buf = b"abcd" * 16384 > -h.pwrite(buf, 32768) > +# Read half of cache-min-block-size > + > zero = h.pread(32768, 0) > assert zero == bytearray(32768) > -buf2 = h.pread(65536, 32768) > -assert buf == buf2 > > -# Flushing should write through to the underlying file. > -h.flush() > +buf = b"abcd" * 8192 > > +# Write past the first read > +with open("cache-block-size.img", "wb") as file: > + file.seek(32768) > + file.write(buf * 2) > + file.truncate(131072) > + > +# Check that it got written > with open("cache-block-size.img", "rb") as file: > - zero = file.read(32768) > - assert zero == bytearray(32768) > + file.seek(32768) > buf2 = file.read(65536) > - assert buf == buf2 > + assert (buf * 2) == buf2 > + > +# Now read the rest of the cache-min-block-size, it should stay empty > +zero = h.pread(32768, 32768) > +assert zero == bytearray(32768) > + > +# Read past that, the pattern should be visible there > +buf2 = h.pread(32768, 65536) > +assert buf == buf2 > ' > -- > 2.32.0 -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v