[RFC PATCH v3 00/27] Add subcluster allocation to qcow2

[Alberto Garcia <berto@igalia.com>]

Hi,

here's the new version of the patches to add subcluster allocation
support to qcow2.

Please refer to the cover letter of the first version for a full
description of the patches:

   https://lists.gnu.org/archive/html/qemu-block/2019-10/msg00983.html

This version fixes many of the problems highlighted by Max. I decided
not to replace completely the cluster logic with subcluster logic in
all cases because I felt that sometimes it only complicated the code.
Let's see what you think :-)

Berto

v3:
- Patch 01: Rename host_offset to host_cluster_offset and make 'bytes'
            an unsigned int [Max]
- Patch 03: Rename cluster_needs_cow to cluster_needs_new_alloc and
            count_cow_clusters to count_single_write_clusters. Update
            documentation and add more assertions and checks [Max]
- Patch 09: Update qcow2_co_truncate() to properly support extended L2
            entries [Max]
- Patch 10: Forbid calling set_l2_bitmap() if the image does not have
            extended L2 entries [Max]
- Patch 11 (new): Add QCow2SubclusterType [Max]
- Patch 12 (new): Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_*
- Patch 13 (new): Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC
- Patch 14: Use QCow2SubclusterType instead of QCow2ClusterType [Max]
- Patch 15: Use QCow2SubclusterType instead of QCow2ClusterType [Max]
- Patch 19: Don't call set_l2_bitmap() if the image does not have
            extended L2 entries [Max]
- Patch 21: Use smaller data types.
- Patch 22: Don't call set_l2_bitmap() if the image does not have
            extended L2 entries [Max]
- Patch 23: Use smaller data types.
- Patch 25: Update test results and documentation. Move the check for
            the minimum subcluster size to validate_cluster_size().
- Patch 26 (new): Add subcluster support to qcow2_measure()
- Patch 27: Add more tests

v2: https://lists.gnu.org/archive/html/qemu-block/2019-10/msg01642.html
- Patch 12: Update after the changes in 88f468e546.
- Patch 21 (new): Clear the L2 bitmap when allocating a compressed
  cluster. Compressed clusters should have the bitmap all set to 0.
- Patch 24: Document the new fields in the QAPI documentation [Eric].
- Patch 25: Allow qcow2 preallocation with backing files.
- Patch 26: Add some tests for qcow2 images with extended L2 entries.

v1: https://lists.gnu.org/archive/html/qemu-block/2019-10/msg00983.html

Output of git backport-diff against v2:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/27:[0013] [FC] 'qcow2: Add calculate_l2_meta()'
002/27:[----] [-C] 'qcow2: Split cluster_needs_cow() out of count_cow_clusters()'
003/27:[0083] [FC] 'qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied()'
004/27:[----] [-C] 'qcow2: Add get_l2_entry() and set_l2_entry()'
005/27:[----] [--] 'qcow2: Document the Extended L2 Entries feature'
006/27:[----] [--] 'qcow2: Add dummy has_subclusters() function'
007/27:[----] [--] 'qcow2: Add subcluster-related fields to BDRVQcow2State'
008/27:[----] [--] 'qcow2: Add offset_to_sc_index()'
009/27:[0008] [FC] 'qcow2: Add l2_entry_size()'
010/27:[0008] [FC] 'qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap()'
011/27:[down] 'qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type()'
012/27:[down] 'qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_*'
013/27:[down] 'qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC'
014/27:[0060] [FC] 'qcow2: Add subcluster support to calculate_l2_meta()'
015/27:[0091] [FC] 'qcow2: Add subcluster support to qcow2_get_cluster_offset()'
016/27:[----] [--] 'qcow2: Add subcluster support to zero_in_l2_slice()'
017/27:[----] [--] 'qcow2: Add subcluster support to discard_in_l2_slice()'
018/27:[----] [--] 'qcow2: Add subcluster support to check_refcounts_l2()'
019/27:[0008] [FC] 'qcow2: Add subcluster support to expand_zero_clusters_in_l1()'
020/27:[----] [--] 'qcow2: Fix offset calculation in handle_dependencies()'
021/27:[0007] [FC] 'qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2()'
022/27:[0004] [FC] 'qcow2: Clear the L2 bitmap when allocating a compressed cluster'
023/27:[0002] [FC] 'qcow2: Add subcluster support to handle_alloc_space()'
024/27:[----] [-C] 'qcow2: Restrict qcow2_co_pwrite_zeroes() to full clusters only'
025/27:[0049] [FC] 'qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit'
026/27:[down] 'qcow2: Add subcluster support to qcow2_measure()'
027/27:[0046] [FC] 'iotests: Add tests for qcow2 images with extended L2 entries'

Alberto Garcia (27):
  qcow2: Add calculate_l2_meta()
  qcow2: Split cluster_needs_cow() out of count_cow_clusters()
  qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied()
  qcow2: Add get_l2_entry() and set_l2_entry()
  qcow2: Document the Extended L2 Entries feature
  qcow2: Add dummy has_subclusters() function
  qcow2: Add subcluster-related fields to BDRVQcow2State
  qcow2: Add offset_to_sc_index()
  qcow2: Add l2_entry_size()
  qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap()
  qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type()
  qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_*
  qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC
  qcow2: Add subcluster support to calculate_l2_meta()
  qcow2: Add subcluster support to qcow2_get_cluster_offset()
  qcow2: Add subcluster support to zero_in_l2_slice()
  qcow2: Add subcluster support to discard_in_l2_slice()
  qcow2: Add subcluster support to check_refcounts_l2()
  qcow2: Add subcluster support to expand_zero_clusters_in_l1()
  qcow2: Fix offset calculation in handle_dependencies()
  qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2()
  qcow2: Clear the L2 bitmap when allocating a compressed cluster
  qcow2: Add subcluster support to handle_alloc_space()
  qcow2: Restrict qcow2_co_pwrite_zeroes() to full clusters only
  qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit
  qcow2: Add subcluster support to qcow2_measure()
  iotests: Add tests for qcow2 images with extended L2 entries

 block/qcow2-cluster.c            | 645 ++++++++++++++++++++-----------
 block/qcow2-refcount.c           |  38 +-
 block/qcow2.c                    | 200 +++++++---
 block/qcow2.h                    | 150 ++++++-
 docs/interop/qcow2.txt           |  68 +++-
 docs/qcow2-cache.txt             |  19 +-
 include/block/block_int.h        |   1 +
 qapi/block-core.json             |   7 +
 tests/qemu-iotests/031.out       |   8 +-
 tests/qemu-iotests/036.out       |   4 +-
 tests/qemu-iotests/049.out       | 102 ++---
 tests/qemu-iotests/060.out       |   1 +
 tests/qemu-iotests/061.out       |  20 +-
 tests/qemu-iotests/065           |  18 +-
 tests/qemu-iotests/082.out       |  48 ++-
 tests/qemu-iotests/085.out       |  38 +-
 tests/qemu-iotests/144.out       |   4 +-
 tests/qemu-iotests/182.out       |   2 +-
 tests/qemu-iotests/185.out       |   8 +-
 tests/qemu-iotests/198.out       |   2 +
 tests/qemu-iotests/206.out       |   4 +
 tests/qemu-iotests/242.out       |   5 +
 tests/qemu-iotests/255.out       |   8 +-
 tests/qemu-iotests/271           | 256 ++++++++++++
 tests/qemu-iotests/271.out       | 208 ++++++++++
 tests/qemu-iotests/273.out       |   9 +-
 tests/qemu-iotests/common.filter |   1 +
 tests/qemu-iotests/group         |   1 +
 28 files changed, 1455 insertions(+), 420 deletions(-)
 create mode 100755 tests/qemu-iotests/271
 create mode 100644 tests/qemu-iotests/271.out

-- 
2.20.1