[Qemu-devel] [PATCH v3 00/15] qemu-img map: Allow driver to return file of the allocated block

[Fam Zheng <famz@redhat.com>]

v3: Add Eric's rev-by in patches 6, 7, 13, 14.
    12: New, split out from the previous 13.
    12->13: Refactor "entry_mergable" from imp_map().
        Don't mess the merge conditions. [Paolo]
        Address Eric's comments:
        - Check has_foo before using foo.
        - Remove blank line between comments and definition in schema.
        - Use PRId64 instead of %ld.
        - Merge short lines.

v2: Add Eric's rev-by in patches 2, 4, 5.
    01: Refering -> referring in commit message. [Eric]
        Recurse to "file" for sensible "zero" flag. [Paolo]
    12: New. Make MapEntry a QAPI struct. [Paolo, Markus]

I stumbled upon this when looking at external bitmap formats.

Current "qemu-img map" command only displays filename if the data is allocated
in bs (bs->file) itself, or in the backing chain. Otherwise, it displays an
unfriendly error message:

    $ qemu-img create -f vmdk -o subformat=monolithicFlat /tmp/test.vmdk 1G

    $ qemu-img map /tmp/test.vmdk 
    Offset          Length          Mapped to       File
    qemu-img: File contains external, encrypted or compressed clusters.

This can be improved. This series extends the .bdrv_co_get_block_status
callback, to let block driver return the BDS of file; then updates all driver
to implement it; and lastly, it changes qemu-img to use this information in
"map" command:

    $ qemu-img map /tmp/test.vmdk 
    Offset          Length          Mapped to       File
    0               0x40000000      0               /tmp/test-flat.vmdk

    $ qemu-img map --output json /tmp/test.vmdk 
    [{"length": 1073741824, "start": 0, "zero": false, "offset": 0, "depth": 0,
      "file": "/tmp/test-flat.vmdk", "data": true}
    ]


Fam Zheng (15):
  block: Add "file" output parameter to block status query functions
  qcow: Assign bs->file->bs to file in qcow_co_get_block_status
  qcow2: Assign bs->file->bs to file in qcow2_co_get_block_status
  raw: Assign bs to file in raw_co_get_block_status
  iscsi: Assign bs to file in iscsi_co_get_block_status
  parallels: Assign bs->file->bs to file in
    parallels_co_get_block_status
  qed: Assign bs->file->bs to file in bdrv_qed_co_get_block_status
  sheepdog: Assign bs to file in sd_co_get_block_status
  vdi: Assign bs->file->bs to file in vdi_co_get_block_status
  vpc: Assign bs->file->bs to file in vpc_co_get_block_status
  vmdk: Return extent's file in bdrv_get_block_status
  qemu-img: In "map", use the returned "file" from bdrv_get_block_status
  qemu-img: Make MapEntry a QAPI struct
  qemu-img: Use QAPI visitor to generate JSON
  iotests: Add "qemu-img map" test for VMDK extents

 block/io.c                 |  42 ++++++++++++-------
 block/iscsi.c              |   9 +++-
 block/mirror.c             |   3 +-
 block/parallels.c          |   3 +-
 block/qcow.c               |   3 +-
 block/qcow2.c              |   3 +-
 block/qed.c                |   6 ++-
 block/raw-posix.c          |   4 +-
 block/raw_bsd.c            |   4 +-
 block/sheepdog.c           |   5 ++-
 block/vdi.c                |   3 +-
 block/vmdk.c               |  13 +++---
 block/vpc.c                |   4 +-
 block/vvfat.c              |   2 +-
 include/block/block.h      |   6 ++-
 include/block/block_int.h  |   3 +-
 qapi/block-core.json       |  27 ++++++++++++
 qemu-img.c                 | 102 +++++++++++++++++++++++++++++----------------
 tests/qemu-iotests/059     |  10 +++++
 tests/qemu-iotests/059.out |  38 +++++++++++++++++
 tests/qemu-iotests/122.out |  96 +++++++++++++++++++++++-------------------
 21 files changed, 270 insertions(+), 116 deletions(-)

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2.4.3