On Fri, Dec 27, 2013 at 11:05:50AM +0800, Hu Tao wrote: > This series implements full image preallocation to create a non-sparse image > file at creation time, both for raw and qcow2 format. The purpose is to avoid > performance deterioration of the guest cause by sparse image. > > v4: - remove bdrv_preallocate and make preallocation a bdrv_create_file > option > - prealloc_mode -> PreallocMode and add it to QAPI > - fix return value in raw_preallocate2 > > Hu Tao (4): > qapi: introduce PreallocMode > raw,qcow2: don't convert file size to sector size > raw-posix: Add full image preallocation option > qcow2: Add full image preallocation option > > block/qcow2.c | 64 > +++++++++++++++++++++++++++++++++++++++++++++---------- > block/raw-posix.c | 50 +++++++++++++++++++++++++++++++++++++++++-- > qapi-schema.json | 12 +++++++++++ > 3 files changed, 113 insertions(+), 13 deletions(-)
I've thought more about the lack of progress information during posix_fallocate(3). Users creating 10s or 100s of GB images may have to wait for a long time if posix_fallocate(3) is implemented in userspace (effectively dd if=/dev/zero of=vm.img). But I think adding preallocate=full is a good starting point. Modern file systems implement it efficiently so the wait time should be negligible. If creating images takes too long we could consider a fancier interface later. I left comments on specific patches.
