Re: [Qemu-devel] [PATCH 1/2] qemu-img: Special post-backing convert handling

2018-05-01 Thread Eric Blake
On 05/01/2018 11:57 AM, Max Reitz wrote: Currently, qemu-img convert writes zeroes when it reads zeroes. Sometimes it does not because the target is initialized to zeroes anyway, so we do not need to overwrite (and thus potentially allocate) it. This is never the case for targets with backing fi

[Qemu-devel] [PATCH 1/2] qemu-img: Special post-backing convert handling

2018-05-01 Thread Max Reitz
Currently, qemu-img convert writes zeroes when it reads zeroes. Sometimes it does not because the target is initialized to zeroes anyway, so we do not need to overwrite (and thus potentially allocate) it. This is never the case for targets with backing files, though. But even them may have an are