[Devel] [PATCH VZ10 v2 0/7] dm-qcow: lseek improvements

[Andrey Zhadchenko]

This patchset is mostly about improving dm-qcow2 lseek speed. L2 md
pages can now be scanned in batch with simple for() instead of heavy
parse_metadata(). Seek qios for backing images are now called with
a range bigger than 1 cluster if possible.
Also fix a few clamping bugs and use correct comparison for seek
modes.

v2:
- patch #4 "fix seek skip to the next L2 table"
 - changed l2 calculation to a simplier round_up
 - allow l2 skip if the backing data does not exist (e.g. lower is
shorter)
- patch #6 "seek unallocated L2 entries in one pass within md"
 - add forgotten to_sector() when skipping unallocated entries
- NEW patch #7 adressing patch #5 edge case when we do to_sector(end),
where 'end' may be not sector aligned, thus causing endless loop.

Andrey Zhadchenko (7):
  drivers/md/dm-qcow2: fix lower delta seek window clamp
  drivers/md/dm-qcow2: keep seek parse window within limit
  drivers/md/dm-qcow2: fix seek constant comparison
  drivers/md/dm-qcow2: fix seek skip to the next L2 table
  drivers/md/dm-qcow2: scan lower delta in one pass over empty L1 entry
  drivers/md/dm-qcow2: seek unallocated L2 entries in one pass within md
  drivers/md/dm-qcow2: forbid unaligned virtual size for images

 drivers/md/dm-qcow2-map.c    | 117 ++++++++++++++++++++++++-----------
 drivers/md/dm-qcow2-target.c |   1 +
 2 files changed, 82 insertions(+), 36 deletions(-)

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2.43.5