This is the start of the latest Delayed COW series. As there seem to be serious problems with the actual Delayed COW (which in fact exist today, but would become a bit easier to hit) and I don't have the time to complete this at the moment, here is another series with preparatory patches, for which there's no reason to not get them applied now.
The result is a somewhat cleaner cluster allocation code in qcow2, and in theory some cases should show improved performance - in practice I think these cases are unlikely to occur, but as the optimisation falls out naturally, let's just take it. Kevin Wolf (19): qcow2: Fix "total clusters" number in bdrv_check qcow2: Remove bogus unlock of s->lock qcow2: Handle dependencies earlier qcow2: Improve check for overlapping allocations qcow2: Change handle_dependency to byte granularity qcow2: Decouple cluster allocation from cluster reuse code qcow2: Factor out handle_alloc() qcow2: handle_alloc(): Get rid of nb_clusters parameter qcow2: handle_alloc(): Get rid of keep_clusters parameter qcow2: Finalise interface of handle_alloc() qcow2: Clean up handle_alloc() qcow2: Factor out handle_copied() qcow2: handle_copied(): Get rid of nb_clusters parameter qcow2: handle_copied(): Get rid of keep_clusters parameter qcow2: handle_copied(): Implement non-zero host_offset qcow2: Use byte granularity in qcow2_alloc_cluster_offset() qcow2: Allow requests with multiple l2metas qcow2: Move cluster gathering to a non-looping loop qcow2: Gather clusters in a looping loop block/qcow2-cluster.c | 491 +++++++++++++++++++++++++++++++-------------- block/qcow2-refcount.c | 4 +- block/qcow2.c | 16 +- block/qcow2.h | 29 +++ tests/qemu-iotests/038.out | 10 +- tests/qemu-iotests/044.out | 4 +- trace-events | 2 + 7 files changed, 394 insertions(+), 162 deletions(-) -- 1.8.1.4
