On Wed, 05/06 16:12, Max Reitz wrote: > On 06.05.2015 15:59, Fam Zheng wrote: > >On Wed, 05/06 15:45, Max Reitz wrote: > >>On 05.05.2015 12:44, Fam Zheng wrote: > >>>Max, > >>> > >>>Since you once fixed VMDK with the json descriptor filename, could you > >>>take a > >>>look at the error: > >>> > >>>$ ./check -vmdk -o "subformat=monolithicFlat" 033 > >>> > >>>033 - output mismatch (see 033.out.bad) > >>>--- /home/fam/qemu/tests/qemu-iotests/033.out 2015-05-05 > >>>10:52:50.524378312 +0800 > >>>+++ 033.out.bad 2015-05-05 17:38:36.147369924 +0800 > >>>@@ -2,54 +2,36 @@ > >>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 > >>> == preparing image == > >>>-wrote 1024/1024 bytes at offset 512 > >>>-1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > >>>-wrote 1536/1536 bytes at offset 131072 > >>>-1.500 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > >>>-wrote 131072/131072 bytes at offset 1024 > >>>-128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > >>>+qemu-io: can't open device blkdebug::/tmp/qemu-iotests/t.vmdk: Cannot use > >>>relative extent paths with VMDK descriptor file 'json:{"image": {"driver": > >>>"file", "filename": "/tmp/qemu-iotests/t.vmdk"}, "driver": "blkdebug", > >>>"align": "512"}' > >>>+qemu-io: can't open device blkdebug::/tmp/qemu-iotests/t.vmdk: Cannot use > >>>relative extent paths with VMDK descriptor file 'json:{"image": {"driver": > >>>"file", "filename": "/tmp/qemu-iotests/t.vmdk"}, "driver": "blkdebug", > >>>"align": "512"}' > >>>+qemu-io: can't open device blkdebug::/tmp/qemu-iotests/t.vmdk: Cannot use > >>>relative extent paths with VMDK descriptor file 'json:{"image": {"driver": > >>>"file", "filename": "/tmp/qemu-iotests/t.vmdk"}, "driver": "blkdebug", > >>>"align": "512"}' > >>> > >>>... > >>> > >>> > >>>I'm not sure what's the best fix here. It's possible to dig out > >>>bs->file->file->filename in this case, but I'm not sure what's the rule of > >>>this > >>>filename mystery. > >>> > >>>Fam > >>Hi Fam, > >> > >>The problem is that the align option is (consciously) set for blkdebug, so > >>the blkdebug driver cannot just convert it to a blkdebug::$foo filename, but > >>must create a JSON filename so that the align option is included. > >> > >>I seem to recall that someone (me? I don't know) once proposed a way for > >>block drivers not only to present a file name (which is json:{${baz}} in > >>this case), but also the name of the directory they are in, or better, a > >>template to which a relative path can be appended (in Unix syntax, that is, > >>with / as separators and .. and so on). The difference to the file name > >>would be that we can ignore all the options given to the block driver for > >>controlling its behavior, we just need a path name. > >> > >>I don't know why we didn't pursue that proposal, but it does seem to be > >>necessary here. > >> > >>I think we can integrate it into the existing bdrv_refresh_filename() > >>"infrastructure", so it shouldn't be too difficult. I can take a shot at it, > >>if you agree. > >> > >Sounds consistent with what we have now, but to be honest I don't have the > >background to agree or disagree. Could you explain (again) why does filename > >have to reflect its option? > > Because in a certain way, having the align option or not results in a > different file (at least in a different behavior). While one could argue > that in this case, it does not make that much of a difference, one can > easily conceive scenarios in which it does (for instance, for blkdebug it > might be an inject-error option). The idea is that the filename reported for > a BDS should result in the same BDS being constructed when used, or at least > one which behaves in the same way.
Who's making use of the json file name? >If you open a file named blkdebug::x.img > with -o inject-error.event=read_aio, then just reporting blkdebug::x.img > would not be correct, since opening a BDS using the filename blkdebug::x.img > alone would not result in a BDS behaving the same. Therefore, we have to > generate a JSON object as the filename which includes this option. > > So while we could solve the problem in this case by ignoring the "align" > option when constructing the filename for blkdebug, it would not work for > the general case. >