[Qemu-devel] [PATCH 0/4] qcow2: Save another common flush

[Kevin Wolf]

For copy on write (this includes any cluster allocations that don't fill the
whole cluster with one request), what qcow2 does looks like this:

1. Allocate new clusters (increase refcounts)
2. bdrv_flush
3. Copy sectors before the first touched one
4. bdrv_flush
5. Copy sectors after the last touched one
6. bdrv_flush
7. Update the L2 table to point to the new clusters

Step 2 and 4 are not necessary. This series moves flushes around to get all
of these three bdrv_flush calls merged into one.

Kevin Wolf (4):
  qcow2: Move sync out of write_refcount_block_entries
  qcow2: Move sync out of update_refcount
  qcow2: Move sync out of qcow2_alloc_clusters
  qcow2: Get rid of additional sync on COW

 block/qcow2-cluster.c  |   11 ++++++++++-
 block/qcow2-refcount.c |   13 ++++++++++++-
 block/qcow2-snapshot.c |    2 ++
 3 files changed, 24 insertions(+), 2 deletions(-)

-- 
1.7.2.2