Created attachment 915873 [details] Comment (This comment was longer than 65,535 characters and has been moved to an attachment by Red Hat Bugzilla).
Note to self: I cannot reproduce this on my own 32 bit Rawhide VM.
Also happens -- though less often -- on x86-64. I asked on linux-fsdevel: http://marc.info/?l=linux-fsdevel&m=139586683225825&w=2
Example failure on x86-64: Sparsify in-place operation completed with no errors. test virt-sparsify: 336296 K -> 18856 K test virt-sparsify --in-place: size_after (18856) too large
I suspect what is happening here is that the journal is not getting trimmed. As there are two filesystems, one of which is 400 MB in size, at least 20 MB or so could potentially be used by the journal. I have changed the test so it measures the reduction in size of the image instead of the final size: https://github.com/libguestfs/libguestfs/commit/595bd5022a251a396050c247003ac60328a7facf