On Thu, Jun 27, 2024 at 2:42 PM Kevin Wolf <kw...@redhat.com> wrote:
> Am 26.06.2024 um 18:27 hat Nir Soffer geschrieben: > > On Wed, Jun 26, 2024 at 12:17 PM Daniel P. Berrangé <berra...@redhat.com > > > > wrote: > > > > > On Mon, Jun 24, 2024 at 06:08:26PM +0200, Kevin Wolf wrote: > > > > Am 24.06.2024 um 17:23 hat Stefan Hajnoczi geschrieben: > > > > > On Wed, Jun 19, 2024 at 08:43:25PM +0300, Nir Soffer wrote: > > > > > > Tested using: > > > > > > > > > > Hi Nir, > > > > > This looks like a good candidate for the qemu-iotests test suite. > > > Adding > > > > > it to the automated tests will protect against future regressions. > > > > > > > > > > Please add the script and the expected output to > > > > > tests/qemu-iotests/test/write-zeroes-unmap and run it using > > > > > `(cd build && tests/qemu-iotests/check write-zeroes-unmap)`. > > > > > > > > > > See the existing test cases in tests/qemu-iotests/ and > > > > > tests/qemu-iotests/tests/ for examples. Some are shell scripts and > > > > > others are Python. I think shell makes sense for this test case. > You > > > > > can copy the test framework boilerplate from an existing test case. > > > > > > > > 'du' can't be used like this in qemu-iotests because it makes > > > > assumptions that depend on the filesystem. A test case replicating > what > > > > Nir did manually would likely fail on XFS with its preallocation. > > > > > > > > Maybe we could operate on a file exposed by the FUSE export that is > > > > backed by qcow2, and then you can use 'qemu-img map' on that qcow2 > image > > > > to verify the allocation status. Somewhat complicated, but I think it > > > > could work. > > > > > > A simpler option would be to use 'du' but with a fuzzy range test, > > > rather than an exact equality test. > > > > > > For the tests which write 1 MB, check the 'du' usage is "at least 1MB", > > > for the tests which expect to unmap blocks, check that the 'du' usage > > > is "less than 256kb". This should be within bounds of xfs speculative > > > allocation. > > > > This should work, I'll start with this approach. > > If we're okay with accepting tests that depend on filesystem behaviour, > then 'qemu-img map -f raw --output=json' should be the less risky > approach than checking 'du'. > Unfortunately it does not work since qemu-img map and qemu-nbd reports the allocated area as zero area with no data. I tried this: $ cat test-print-allocation.sh #!/bin/sh qemu=${1:?Usage: $0 qemu-executable} img=/tmp/qemu-test-unmap.img echo echo "discard=unmap - write zeroes" fallocate -l 1m $img echo -e 'qemu-io none0 "write -z 0 1m"\nquit' | $qemu -monitor stdio \ -drive if=none,file=$img,format=raw,discard=unmap >/dev/null echo "du:" du -sh $img echo "qemu-img map:" qemu-img map -f raw --output json $img echo "nbdinfo --map:" nbdinfo --map -- [ qemu-nbd -r -f raw $img ] echo echo "discard=unmap - write zeroes unmap" fallocate -l 1m $img echo -e 'qemu-io none0 "write -zu 0 1m"\nquit' | $qemu -monitor stdio \ -drive if=none,file=$img,format=raw,discard=unmap >/dev/null echo "du:" du -sh $img echo "qemu-img map:" qemu-img map -f raw --output json $img echo "nbdinfo --map:" nbdinfo --map -- [ qemu-nbd -r -f raw $img ] rm $img $ ./test-print-allocation.sh ./qemu-system-x86_64 discard=unmap - write zeroes du: 1.0M /tmp/qemu-test-unmap.img qemu-img map: [{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false, "offset": 0}] nbdinfo --map: 0 1048576 3 hole,zero discard=unmap - write zeroes unmap du: 0 /tmp/qemu-test-unmap.img qemu-img map: [{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false, "offset": 0}] nbdinfo --map: 0 1048576 3 hole,zero