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[Qemu-devel] [PATCH v9 00/21] qcow2: persistent dirty bitmaps


From: Vladimir Sementsov-Ogievskiy
Subject: [Qemu-devel] [PATCH v9 00/21] qcow2: persistent dirty bitmaps
Date: Tue, 22 Nov 2016 20:26:05 +0300

Hi all!

There is a new update of qcow2-bitmap series - v9.

web: 
https://src.openvz.org/users/vsementsov/repos/qemu/browse?at=qcow2-bitmap-v9
git: https://src.openvz.org/scm/~vsementsov/qemu.git (tag qcow2-bitmap-v9)

v9:

rebase on master!

01-04,06,07: John's r-b
03: rewording in comment ("The concurrent resetting ..."), John's r-b
07: reword error messages
    commit message: dirty bitmap -> bitmap
09: fix uninitialized ret in bitmap_list_store() (fix compilation warning)
18: fix compilation of tests/test-hbitmap

also, change constants names for qcow2: DIRTY_BITMAP -> BITMAP (as it is not
dirty bitmaps extension, but just bitmaps extension), QCOW -> QCOW2 (bitmaps
are only for qcow2)

v8:

Patches 01-06 are mostly unchanged, except for spelling and wording.
02 - add Eric's r-b
03,04 - add Max's r-b

07-09 is refactored "bitmap-read" part of the feature. Main changes:
- introduce bitmap list - normal list, which represents bitmap directory.
  Function bitmap_list_load loads bitmap directory, checks everything and
  creates normal list.
- introduce .bdrv_load_autoloading_dirty_bitmaps : instead of loading bitmaps
  in qcow2_open, lets load them only in bdrv_open, to avoid reloading in 
  bdrv_snapshot_goto
- do not delete bitmaps after read, but mark them IN_USE

10 has contextual changes and rewording of comment. I've added Max's r-b, hope 
it's ok.

11: add error_report("Persistent bitmaps are lost") in case of failed bitmap 
store

12: add Max's r-b

13 is refactored "bitmap-store" part of the feature. see 07-09 description
- for now I just free old clusters and allocate new. This will be improved
  with a separate patch.

patch about "delete bitmaps on truncate" is removed. This case will be handled 
later.
IN_USE, autoclear, check-constraints things are merged into other patches.

14-15 are mew patches, to early check possibility of creating persistent bitmap 
with
  specified name and granularity in specified BDS

16-17: spelling, rewording, indenting, tiny code simplifying, check can_store 
(by 14-15),
    s/if (autoload && !persistent)/if (has_autoload && !persistent)/,
    rebase (deleted qmp-commands.hx)

18: alternative to md5 in query-block:
  - separated qmp command -x-debug-block-dirty-bitmap-sha256
  - as adviced by Daniel P. Berrange in my parallel thread:
    - sha256 instead of md5
    - use qcrypto_hash_* instead of GChecksum
  - fix bug =) (size was wrong in hbitmap_md5)

19: s/3999/3fff/, use x-debug-block-dirty-bitmap-sha256

20: new patch to rename and publish inc_refcounts

21: some fixes and refactoring mostyly by Max's comments.

Max, Eric, great tanks for your review!
I hope, I've covered most of your comments by this update.

TODO:
- handle reopening image RO->RW and incoming migration, set IN_USE for existing 
loaded bitmaps
  in these cases.
- reuse old, already allocated data clusters for bitmaps storing
- truncate bitmaps in the image on truncate


v7:

https://src.openvz.org/users/vsementsov/repos/qemu/browse?at=refs%2Ftags%2Fqcow2-bitmap-v7
based on block-next (https://github.com/XanClic/qemu/commits/block-next)

- a lot of refactoring and reordering of patches.
- dead code removed (bdrv_dirty_bitmap_load, etc.)
- do not maintain extra data for now
- do not store dirty bitmap directory in memory
  (as we use it seldom, we can just reread if needed)

By Kevin's review:
01 - commit message changed: fix->improvement (as it was not a bug)
03 - r-b
04 - r-b
05 - add 21 patch to fix spec, also, removed all (I hope) mentions of
     "Bitmap Header", switch to one unified name for it - "Bitmap
     Directory Entry", to avoid misunderstanding with Qcow2 header.
     (also, add patch 22, to fix it in spec)
v6.06 - improve for_each_dir_entry loop, reorder patches, other small fixes
v6.07 ~> v7.09 - dead code removed, I've moved to one function 
        .bdrv_store_persistent_bitmaps and have wrapper and callback in one
        patch (with also some other staff. If it not ok, I can split them)
v6.08 - about keeping bitmap directory instead of bitmap list: no I don't keep
        it at all.
v6.16 - old bdrv_ bitmap-storing related functions are removed. The new one is
        bdrv_store_persistent_bitmaps.


v6:
https://src.openvz.org/users/vsementsov/repos/qemu/browse?at=refs%2Ftags%2Fqcow2-bitmap-v6
based on block-next (https://github.com/XanClic/qemu/commits/block-next)

There are a lot of changes, reorderings and additions in comparement with v5.
One principal thing: now bitmaps are removed from image after loading instead
of marking them in_use. It is simpler and we do not need to store superfluous 
data.
Also, we are no more interested in command line interface to dirty bitmaps.
So it is dropped.  If someone needs it I can add it later.

Vladimir Sementsov-Ogievskiy (21):
  specs/qcow2: fix bitmap granularity qemu-specific note
  specs/qcow2: do not use wording 'bitmap header'
  hbitmap: improve dirty iter
  tests: add hbitmap iter test
  block: fix bdrv_dirty_bitmap_granularity signature
  block/dirty-bitmap: add deserialize_ones func
  qcow2: add bitmaps extension
  block: introduce auto-loading bitmaps
  qcow2: add .bdrv_load_autoloading_dirty_bitmaps
  block/dirty-bitmap: add autoload field to BdrvDirtyBitmap
  block: introduce persistent dirty bitmaps
  block/dirty-bitmap: add bdrv_dirty_bitmap_next()
  qcow2: add .bdrv_store_persistent_dirty_bitmaps()
  block: add bdrv_can_store_dirty_bitmap
  qcow2: add .bdrv_can_store_dirty_bitmap
  qmp: add persistent flag to block-dirty-bitmap-add
  qmp: add autoload parameter to block-dirty-bitmap-add
  qmp: add x-debug-block-dirty-bitmap-sha256
  iotests: test qcow2 persistent dirty bitmap
  qcow2-refcount: rename inc_refcounts() and make it public
  qcow2-bitmap: refcounts

 block.c                      |   67 +++
 block/Makefile.objs          |    2 +-
 block/dirty-bitmap.c         |   63 ++-
 block/qcow2-bitmap.c         | 1230 ++++++++++++++++++++++++++++++++++++++++++
 block/qcow2-refcount.c       |   59 +-
 block/qcow2.c                |  111 +++-
 block/qcow2.h                |   39 ++
 blockdev.c                   |   64 ++-
 docs/qmp-commands.txt        |    7 +
 docs/specs/qcow2.txt         |    8 +-
 include/block/block.h        |    5 +
 include/block/block_int.h    |    7 +
 include/block/dirty-bitmap.h |   18 +-
 include/qemu/hbitmap.h       |   49 +-
 qapi/block-core.json         |   37 +-
 tests/Makefile.include       |    2 +-
 tests/qemu-iotests/165       |   89 +++
 tests/qemu-iotests/165.out   |    5 +
 tests/qemu-iotests/group     |    1 +
 tests/test-hbitmap.c         |   19 +
 util/hbitmap.c               |   51 +-
 21 files changed, 1872 insertions(+), 61 deletions(-)
 create mode 100644 block/qcow2-bitmap.c
 create mode 100755 tests/qemu-iotests/165
 create mode 100644 tests/qemu-iotests/165.out

-- 
1.8.3.1




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