[Qemu-devel] [PATCH v4 0/27] write/create for Parallels images with reasonable performance

["Denis V. Lunev" <den@openvz.org>]

This patchset provides an ability to create of/write to Parallels
images and some testing of the new code. Readings and writings are
optimized out and I expect the same or slightly better performance
as qcow2.

Changes from v4:
- parallels format driver marked as bdrv_has_zero_init_1
- added missed unlocks to parallels_co_readv/writev on error path, locking
  is shortened and simplified
- changed test number for created images
- added check for bdrv_has_zero_init() and availability of bdrv_truncate()
  in parallels_open() and proper error handling in alloc_cluster
- some patch comments are improved

Changes from v3:
- fixed checkpatch warnings even in just moved code. I am tired of them
- fixed contingency check in patch 18

Changes from v2:
- read performance is almost doubled (up to 360 Mb/sec), write performance
  is improved by 15-20%
- bat caching approach changed completely. bat_bitmap now contains the data
  in on-disk format, which allows to use this data for metadata cache
- incorrect close detection code is added (inuse field in the header)
- very basic check consistency code added

Changes from v1:
- patches 13-19 added, which boosts performance from 800 KiB/sec to
  near native performance

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Roman Kagan <rkagan@parallels.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>