mbox series

[v9,00/31] block: Fix some filename generation issues

Message ID 20180628000745.4477-1-mreitz@redhat.com
Headers show
Series block: Fix some filename generation issues | expand

Message

Max Reitz June 28, 2018, 12:07 a.m. UTC
Once more, I’ll spare both me and you another iteration of the cover
letter, so see here:

http://lists.nongnu.org/archive/html/qemu-block/2017-09/msg01030.html

(Although this series no longer includes a @base-directory option.)

In regards to the last version, the biggest change is that I dropped
backing_overridden and instead try to compare the filename from the
image header with the filename of the actual backing BDS to find out
whether the backing file has been overridden.

In order that this doesn’t break whenever the header contains a slightly
unusual (“non-canonical”) backing filename (e.g. “file:foo.qcow2” or
“nbd:localhost:10809” instead of “nbd://localhost:10809”, i.e. something
different from what bdrv_refresh_filename() would generate), when the
reference filename in the BDS (auto_backing_file) is used to open the
backing file, it is updated from the backing BDS's resulting filename.


All (I hope) changes in v9:
- Rebase (warranting an NVME patch)

- Dropped backing_overridden, switched to the comparison described above
  (and dealt with the fallout, for example test 191 can now stay
  unchanged)

- Removed all existing bdrv_refresh_filename() calls and moved them to
  the users of BDS.filename (first patch) -- otherwise, I got iotest
  failure (because it's hard to reflect all graph changes properly with
  a “pushing” bdrv_refresh_filename()), and I don't even want to
  remember how 191 broke without this change.

- Renamed “significant options” to “strong options”

- Implicit nodes should be completely skipped in
  bdrv_refresh_filename(), including setting of bs->full_open_options
  (patch 3)

- vmdk_gather_child_options() failed to set backing=null when the image
  header asked for a backing file, but the user forbid its use

- Added the penultimate patch which makes json:{} filenames for explicit
  internal nodes kind of working?
  (When you specify @filter-node e.g. for block-commit, the node should
  be visible, so it may appear in a json:{} filename; but creating that
  node did not take a real options QDict, so it was lacking the @driver
  option, and that was a bit sad.)

- Dropped a superfluous “suspend.” in blkdebug

- Dropped the first patch of v8

- Restyled some comments (“/*” on its own line where “*/” is on its own
  line)

- Fixed mention of "NBD" in the NFS patch (18)


git-backport-diff against v8:

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

001/31:[down] 'block: Use bdrv_refresh_filename() to pull'
002/31:[----] [--] 'block: Use children list in bdrv_refresh_filename'
003/31:[down] 'block: Skip implicit nodes for filename info'
004/31:[down] 'block: Add BDS.auto_backing_file'
005/31:[0052] [FC] 'block: Respect backing bs in bdrv_refresh_filename'
006/31:[down] 'iotests.py: Add filter_imgfmt()'
007/31:[down] 'iotests.py: Add node_info()'
008/31:[down] 'iotests: Add test for backing file overrides'
009/31:[----] [--] 'block: Make path_combine() return the path'
010/31:[0016] [FC] 'block: bdrv_get_full_backing_filename_from_...'s ret. val.'
011/31:[0001] [FC] 'block: bdrv_get_full_backing_filename's ret. val.'
012/31:[0022] [FC] 'block: Add bdrv_make_absolute_filename()'
013/31:[0003] [FC] 'block: Fix bdrv_find_backing_image()'
014/31:[0001] [FC] 'block: Add bdrv_dirname()'
015/31:[----] [--] 'blkverify: Make bdrv_dirname() return NULL'
016/31:[----] [-C] 'quorum: Make bdrv_dirname() return NULL'
017/31:[----] [-C] 'block/nbd: Make bdrv_dirname() return NULL'
018/31:[0003] [FC] 'block/nfs: Implement bdrv_dirname()'
019/31:[0014] [FC] 'block: Use bdrv_dirname() for relative filenames'
020/31:[----] [--] 'iotests: Add quorum case to test 110'
021/31:[down] 'block: Add strong_runtime_opts to BlockDriver'
022/31:[0037] [FC] 'block: Add BlockDriver.bdrv_gather_child_options'
023/31:[0084] [FC] 'block: Generically refresh runtime options'
024/31:[0076] [FC] 'block: Purify .bdrv_refresh_filename()'
025/31:[0005] [FC] 'block: Do not copy exact_filename from format file'
026/31:[down] 'block/nvme: Fix bdrv_refresh_filename()'
027/31:[----] [--] 'block/curl: Harmonize option defaults'
028/31:[----] [-C] 'block/curl: Implement bdrv_refresh_filename()'
029/31:[----] [--] 'block/null: Generate filename even with latency-ns'
030/31:[down] 'block: BDS options may lack the "driver" option'
031/31:[down] 'iotests: Test json:{} filenames of internal BDSs'


Max Reitz (31):
  block: Use bdrv_refresh_filename() to pull
  block: Use children list in bdrv_refresh_filename
  block: Skip implicit nodes for filename info
  block: Add BDS.auto_backing_file
  block: Respect backing bs in bdrv_refresh_filename
  iotests.py: Add filter_imgfmt()
  iotests.py: Add node_info()
  iotests: Add test for backing file overrides
  block: Make path_combine() return the path
  block: bdrv_get_full_backing_filename_from_...'s ret. val.
  block: bdrv_get_full_backing_filename's ret. val.
  block: Add bdrv_make_absolute_filename()
  block: Fix bdrv_find_backing_image()
  block: Add bdrv_dirname()
  blkverify: Make bdrv_dirname() return NULL
  quorum: Make bdrv_dirname() return NULL
  block/nbd: Make bdrv_dirname() return NULL
  block/nfs: Implement bdrv_dirname()
  block: Use bdrv_dirname() for relative filenames
  iotests: Add quorum case to test 110
  block: Add strong_runtime_opts to BlockDriver
  block: Add BlockDriver.bdrv_gather_child_options
  block: Generically refresh runtime options
  block: Purify .bdrv_refresh_filename()
  block: Do not copy exact_filename from format file
  block/nvme: Fix bdrv_refresh_filename()
  block/curl: Harmonize option defaults
  block/curl: Implement bdrv_refresh_filename()
  block/null: Generate filename even with latency-ns
  block: BDS options may lack the "driver" option
  iotests: Test json:{} filenames of internal BDSs

 include/block/block.h         |  16 +-
 include/block/block_int.h     |  48 +++-
 block.c                       | 505 ++++++++++++++++++++++------------
 block/blkdebug.c              |  70 ++---
 block/blkverify.c             |  29 +-
 block/commit.c                |   3 +-
 block/crypto.c                |   8 +
 block/curl.c                  |  55 +++-
 block/gluster.c               |  19 ++
 block/iscsi.c                 |  18 ++
 block/mirror.c                |   3 +-
 block/nbd.c                   |  46 ++--
 block/nfs.c                   |  54 ++--
 block/null.c                  |  32 ++-
 block/nvme.c                  |  27 +-
 block/qapi.c                  |  16 +-
 block/qcow.c                  |  14 +-
 block/qcow2.c                 |  17 +-
 block/qed.c                   |   7 +-
 block/quorum.c                |  71 +++--
 block/raw-format.c            |  11 +-
 block/rbd.c                   |  14 +
 block/replication.c           |  10 +-
 block/sheepdog.c              |  12 +
 block/ssh.c                   |  12 +
 block/throttle.c              |   7 +
 block/vhdx-log.c              |   1 +
 block/vmdk.c                  |  43 ++-
 block/vpc.c                   |  11 +-
 block/vvfat.c                 |  12 +
 block/vxhs.c                  |  11 +
 blockdev.c                    |   8 +
 qemu-img.c                    |  12 +-
 tests/qemu-iotests/051.out    |   8 +-
 tests/qemu-iotests/051.pc.out |   8 +-
 tests/qemu-iotests/110        |  29 +-
 tests/qemu-iotests/110.out    |   9 +-
 tests/qemu-iotests/223        | 235 ++++++++++++++++
 tests/qemu-iotests/223.out    |  84 ++++++
 tests/qemu-iotests/224        | 139 ++++++++++
 tests/qemu-iotests/224.out    |  18 ++
 tests/qemu-iotests/group      |   2 +
 tests/qemu-iotests/iotests.py |  10 +
 43 files changed, 1374 insertions(+), 390 deletions(-)
 create mode 100755 tests/qemu-iotests/223
 create mode 100644 tests/qemu-iotests/223.out
 create mode 100755 tests/qemu-iotests/224
 create mode 100644 tests/qemu-iotests/224.out

Comments

Max Reitz July 13, 2018, 9:49 a.m. UTC | #1
Ping – any thoughts on the design, Kevin?


(Continuing to see how much of a mess our backing filename handling is
(half of the time, bs->backing_file is seen as a value in the image
header (so relative paths are interpreted relatively to the overlay),
half of the time it is seen as a cache of bs->backing->bs->filename (so
relative paths are given relatively to qemu)), I am nearly inclined to
move off the first part of this series that deals with detecting changed
backing files until later, when I try to tackle that bs->backing_file
issue.)


On 2018-06-28 02:07, Max Reitz wrote:
> Once more, I’ll spare both me and you another iteration of the cover
> letter, so see here:
> 
> http://lists.nongnu.org/archive/html/qemu-block/2017-09/msg01030.html
> 
> (Although this series no longer includes a @base-directory option.)
> 
> In regards to the last version, the biggest change is that I dropped
> backing_overridden and instead try to compare the filename from the
> image header with the filename of the actual backing BDS to find out
> whether the backing file has been overridden.
> 
> In order that this doesn’t break whenever the header contains a slightly
> unusual (“non-canonical”) backing filename (e.g. “file:foo.qcow2” or
> “nbd:localhost:10809” instead of “nbd://localhost:10809”, i.e. something
> different from what bdrv_refresh_filename() would generate), when the
> reference filename in the BDS (auto_backing_file) is used to open the
> backing file, it is updated from the backing BDS's resulting filename.
> 
> 
> All (I hope) changes in v9:
> - Rebase (warranting an NVME patch)
> 
> - Dropped backing_overridden, switched to the comparison described above
>   (and dealt with the fallout, for example test 191 can now stay
>   unchanged)
> 
> - Removed all existing bdrv_refresh_filename() calls and moved them to
>   the users of BDS.filename (first patch) -- otherwise, I got iotest
>   failure (because it's hard to reflect all graph changes properly with
>   a “pushing” bdrv_refresh_filename()), and I don't even want to
>   remember how 191 broke without this change.
> 
> - Renamed “significant options” to “strong options”
> 
> - Implicit nodes should be completely skipped in
>   bdrv_refresh_filename(), including setting of bs->full_open_options
>   (patch 3)
> 
> - vmdk_gather_child_options() failed to set backing=null when the image
>   header asked for a backing file, but the user forbid its use
> 
> - Added the penultimate patch which makes json:{} filenames for explicit
>   internal nodes kind of working?
>   (When you specify @filter-node e.g. for block-commit, the node should
>   be visible, so it may appear in a json:{} filename; but creating that
>   node did not take a real options QDict, so it was lacking the @driver
>   option, and that was a bit sad.)
> 
> - Dropped a superfluous “suspend.” in blkdebug
> 
> - Dropped the first patch of v8
> 
> - Restyled some comments (“/*” on its own line where “*/” is on its own
>   line)
> 
> - Fixed mention of "NBD" in the NFS patch (18)
> 
> 
> git-backport-diff against v8:
> 
> 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
> 
> 001/31:[down] 'block: Use bdrv_refresh_filename() to pull'
> 002/31:[----] [--] 'block: Use children list in bdrv_refresh_filename'
> 003/31:[down] 'block: Skip implicit nodes for filename info'
> 004/31:[down] 'block: Add BDS.auto_backing_file'
> 005/31:[0052] [FC] 'block: Respect backing bs in bdrv_refresh_filename'
> 006/31:[down] 'iotests.py: Add filter_imgfmt()'
> 007/31:[down] 'iotests.py: Add node_info()'
> 008/31:[down] 'iotests: Add test for backing file overrides'
> 009/31:[----] [--] 'block: Make path_combine() return the path'
> 010/31:[0016] [FC] 'block: bdrv_get_full_backing_filename_from_...'s ret. val.'
> 011/31:[0001] [FC] 'block: bdrv_get_full_backing_filename's ret. val.'
> 012/31:[0022] [FC] 'block: Add bdrv_make_absolute_filename()'
> 013/31:[0003] [FC] 'block: Fix bdrv_find_backing_image()'
> 014/31:[0001] [FC] 'block: Add bdrv_dirname()'
> 015/31:[----] [--] 'blkverify: Make bdrv_dirname() return NULL'
> 016/31:[----] [-C] 'quorum: Make bdrv_dirname() return NULL'
> 017/31:[----] [-C] 'block/nbd: Make bdrv_dirname() return NULL'
> 018/31:[0003] [FC] 'block/nfs: Implement bdrv_dirname()'
> 019/31:[0014] [FC] 'block: Use bdrv_dirname() for relative filenames'
> 020/31:[----] [--] 'iotests: Add quorum case to test 110'
> 021/31:[down] 'block: Add strong_runtime_opts to BlockDriver'
> 022/31:[0037] [FC] 'block: Add BlockDriver.bdrv_gather_child_options'
> 023/31:[0084] [FC] 'block: Generically refresh runtime options'
> 024/31:[0076] [FC] 'block: Purify .bdrv_refresh_filename()'
> 025/31:[0005] [FC] 'block: Do not copy exact_filename from format file'
> 026/31:[down] 'block/nvme: Fix bdrv_refresh_filename()'
> 027/31:[----] [--] 'block/curl: Harmonize option defaults'
> 028/31:[----] [-C] 'block/curl: Implement bdrv_refresh_filename()'
> 029/31:[----] [--] 'block/null: Generate filename even with latency-ns'
> 030/31:[down] 'block: BDS options may lack the "driver" option'
> 031/31:[down] 'iotests: Test json:{} filenames of internal BDSs'
> 
> 
> Max Reitz (31):
>   block: Use bdrv_refresh_filename() to pull
>   block: Use children list in bdrv_refresh_filename
>   block: Skip implicit nodes for filename info
>   block: Add BDS.auto_backing_file
>   block: Respect backing bs in bdrv_refresh_filename
>   iotests.py: Add filter_imgfmt()
>   iotests.py: Add node_info()
>   iotests: Add test for backing file overrides
>   block: Make path_combine() return the path
>   block: bdrv_get_full_backing_filename_from_...'s ret. val.
>   block: bdrv_get_full_backing_filename's ret. val.
>   block: Add bdrv_make_absolute_filename()
>   block: Fix bdrv_find_backing_image()
>   block: Add bdrv_dirname()
>   blkverify: Make bdrv_dirname() return NULL
>   quorum: Make bdrv_dirname() return NULL
>   block/nbd: Make bdrv_dirname() return NULL
>   block/nfs: Implement bdrv_dirname()
>   block: Use bdrv_dirname() for relative filenames
>   iotests: Add quorum case to test 110
>   block: Add strong_runtime_opts to BlockDriver
>   block: Add BlockDriver.bdrv_gather_child_options
>   block: Generically refresh runtime options
>   block: Purify .bdrv_refresh_filename()
>   block: Do not copy exact_filename from format file
>   block/nvme: Fix bdrv_refresh_filename()
>   block/curl: Harmonize option defaults
>   block/curl: Implement bdrv_refresh_filename()
>   block/null: Generate filename even with latency-ns
>   block: BDS options may lack the "driver" option
>   iotests: Test json:{} filenames of internal BDSs
> 
>  include/block/block.h         |  16 +-
>  include/block/block_int.h     |  48 +++-
>  block.c                       | 505 ++++++++++++++++++++++------------
>  block/blkdebug.c              |  70 ++---
>  block/blkverify.c             |  29 +-
>  block/commit.c                |   3 +-
>  block/crypto.c                |   8 +
>  block/curl.c                  |  55 +++-
>  block/gluster.c               |  19 ++
>  block/iscsi.c                 |  18 ++
>  block/mirror.c                |   3 +-
>  block/nbd.c                   |  46 ++--
>  block/nfs.c                   |  54 ++--
>  block/null.c                  |  32 ++-
>  block/nvme.c                  |  27 +-
>  block/qapi.c                  |  16 +-
>  block/qcow.c                  |  14 +-
>  block/qcow2.c                 |  17 +-
>  block/qed.c                   |   7 +-
>  block/quorum.c                |  71 +++--
>  block/raw-format.c            |  11 +-
>  block/rbd.c                   |  14 +
>  block/replication.c           |  10 +-
>  block/sheepdog.c              |  12 +
>  block/ssh.c                   |  12 +
>  block/throttle.c              |   7 +
>  block/vhdx-log.c              |   1 +
>  block/vmdk.c                  |  43 ++-
>  block/vpc.c                   |  11 +-
>  block/vvfat.c                 |  12 +
>  block/vxhs.c                  |  11 +
>  blockdev.c                    |   8 +
>  qemu-img.c                    |  12 +-
>  tests/qemu-iotests/051.out    |   8 +-
>  tests/qemu-iotests/051.pc.out |   8 +-
>  tests/qemu-iotests/110        |  29 +-
>  tests/qemu-iotests/110.out    |   9 +-
>  tests/qemu-iotests/223        | 235 ++++++++++++++++
>  tests/qemu-iotests/223.out    |  84 ++++++
>  tests/qemu-iotests/224        | 139 ++++++++++
>  tests/qemu-iotests/224.out    |  18 ++
>  tests/qemu-iotests/group      |   2 +
>  tests/qemu-iotests/iotests.py |  10 +
>  43 files changed, 1374 insertions(+), 390 deletions(-)
>  create mode 100755 tests/qemu-iotests/223
>  create mode 100644 tests/qemu-iotests/223.out
>  create mode 100755 tests/qemu-iotests/224
>  create mode 100644 tests/qemu-iotests/224.out
>
Ari Sundholm July 19, 2018, 12:53 p.m. UTC | #2
On 07/13/2018 12:49 PM, Max Reitz wrote:
> Ping – any thoughts on the design, Kevin?
> 
> 
> (Continuing to see how much of a mess our backing filename handling is
> (half of the time, bs->backing_file is seen as a value in the image
> header (so relative paths are interpreted relatively to the overlay),
> half of the time it is seen as a cache of bs->backing->bs->filename (so
> relative paths are given relatively to qemu)), I am nearly inclined to
> move off the first part of this series that deals with detecting changed
> backing files until later, when I try to tackle that bs->backing_file
> issue.)
> 

I'm not Kevin, but it seems this series needs updating to accommodate 
the recent addition of the blklogwrites block driver.

Best regards,
Ari Sundholm
ari@tuxera.com

> 
> On 2018-06-28 02:07, Max Reitz wrote:
>> Once more, I’ll spare both me and you another iteration of the cover
>> letter, so see here:
>>
>> http://lists.nongnu.org/archive/html/qemu-block/2017-09/msg01030.html
>>
>> (Although this series no longer includes a @base-directory option.)
>>
>> In regards to the last version, the biggest change is that I dropped
>> backing_overridden and instead try to compare the filename from the
>> image header with the filename of the actual backing BDS to find out
>> whether the backing file has been overridden.
>>
>> In order that this doesn’t break whenever the header contains a slightly
>> unusual (“non-canonical”) backing filename (e.g. “file:foo.qcow2” or
>> “nbd:localhost:10809” instead of “nbd://localhost:10809”, i.e. something
>> different from what bdrv_refresh_filename() would generate), when the
>> reference filename in the BDS (auto_backing_file) is used to open the
>> backing file, it is updated from the backing BDS's resulting filename.
>>
>>
>> All (I hope) changes in v9:
>> - Rebase (warranting an NVME patch)
>>
>> - Dropped backing_overridden, switched to the comparison described above
>>    (and dealt with the fallout, for example test 191 can now stay
>>    unchanged)
>>
>> - Removed all existing bdrv_refresh_filename() calls and moved them to
>>    the users of BDS.filename (first patch) -- otherwise, I got iotest
>>    failure (because it's hard to reflect all graph changes properly with
>>    a “pushing” bdrv_refresh_filename()), and I don't even want to
>>    remember how 191 broke without this change.
>>
>> - Renamed “significant options” to “strong options”
>>
>> - Implicit nodes should be completely skipped in
>>    bdrv_refresh_filename(), including setting of bs->full_open_options
>>    (patch 3)
>>
>> - vmdk_gather_child_options() failed to set backing=null when the image
>>    header asked for a backing file, but the user forbid its use
>>
>> - Added the penultimate patch which makes json:{} filenames for explicit
>>    internal nodes kind of working?
>>    (When you specify @filter-node e.g. for block-commit, the node should
>>    be visible, so it may appear in a json:{} filename; but creating that
>>    node did not take a real options QDict, so it was lacking the @driver
>>    option, and that was a bit sad.)
>>
>> - Dropped a superfluous “suspend.” in blkdebug
>>
>> - Dropped the first patch of v8
>>
>> - Restyled some comments (“/*” on its own line where “*/” is on its own
>>    line)
>>
>> - Fixed mention of "NBD" in the NFS patch (18)
>>
>>
>> git-backport-diff against v8:
>>
>> 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
>>
>> 001/31:[down] 'block: Use bdrv_refresh_filename() to pull'
>> 002/31:[----] [--] 'block: Use children list in bdrv_refresh_filename'
>> 003/31:[down] 'block: Skip implicit nodes for filename info'
>> 004/31:[down] 'block: Add BDS.auto_backing_file'
>> 005/31:[0052] [FC] 'block: Respect backing bs in bdrv_refresh_filename'
>> 006/31:[down] 'iotests.py: Add filter_imgfmt()'
>> 007/31:[down] 'iotests.py: Add node_info()'
>> 008/31:[down] 'iotests: Add test for backing file overrides'
>> 009/31:[----] [--] 'block: Make path_combine() return the path'
>> 010/31:[0016] [FC] 'block: bdrv_get_full_backing_filename_from_...'s ret. val.'
>> 011/31:[0001] [FC] 'block: bdrv_get_full_backing_filename's ret. val.'
>> 012/31:[0022] [FC] 'block: Add bdrv_make_absolute_filename()'
>> 013/31:[0003] [FC] 'block: Fix bdrv_find_backing_image()'
>> 014/31:[0001] [FC] 'block: Add bdrv_dirname()'
>> 015/31:[----] [--] 'blkverify: Make bdrv_dirname() return NULL'
>> 016/31:[----] [-C] 'quorum: Make bdrv_dirname() return NULL'
>> 017/31:[----] [-C] 'block/nbd: Make bdrv_dirname() return NULL'
>> 018/31:[0003] [FC] 'block/nfs: Implement bdrv_dirname()'
>> 019/31:[0014] [FC] 'block: Use bdrv_dirname() for relative filenames'
>> 020/31:[----] [--] 'iotests: Add quorum case to test 110'
>> 021/31:[down] 'block: Add strong_runtime_opts to BlockDriver'
>> 022/31:[0037] [FC] 'block: Add BlockDriver.bdrv_gather_child_options'
>> 023/31:[0084] [FC] 'block: Generically refresh runtime options'
>> 024/31:[0076] [FC] 'block: Purify .bdrv_refresh_filename()'
>> 025/31:[0005] [FC] 'block: Do not copy exact_filename from format file'
>> 026/31:[down] 'block/nvme: Fix bdrv_refresh_filename()'
>> 027/31:[----] [--] 'block/curl: Harmonize option defaults'
>> 028/31:[----] [-C] 'block/curl: Implement bdrv_refresh_filename()'
>> 029/31:[----] [--] 'block/null: Generate filename even with latency-ns'
>> 030/31:[down] 'block: BDS options may lack the "driver" option'
>> 031/31:[down] 'iotests: Test json:{} filenames of internal BDSs'
>>
>>
>> Max Reitz (31):
>>    block: Use bdrv_refresh_filename() to pull
>>    block: Use children list in bdrv_refresh_filename
>>    block: Skip implicit nodes for filename info
>>    block: Add BDS.auto_backing_file
>>    block: Respect backing bs in bdrv_refresh_filename
>>    iotests.py: Add filter_imgfmt()
>>    iotests.py: Add node_info()
>>    iotests: Add test for backing file overrides
>>    block: Make path_combine() return the path
>>    block: bdrv_get_full_backing_filename_from_...'s ret. val.
>>    block: bdrv_get_full_backing_filename's ret. val.
>>    block: Add bdrv_make_absolute_filename()
>>    block: Fix bdrv_find_backing_image()
>>    block: Add bdrv_dirname()
>>    blkverify: Make bdrv_dirname() return NULL
>>    quorum: Make bdrv_dirname() return NULL
>>    block/nbd: Make bdrv_dirname() return NULL
>>    block/nfs: Implement bdrv_dirname()
>>    block: Use bdrv_dirname() for relative filenames
>>    iotests: Add quorum case to test 110
>>    block: Add strong_runtime_opts to BlockDriver
>>    block: Add BlockDriver.bdrv_gather_child_options
>>    block: Generically refresh runtime options
>>    block: Purify .bdrv_refresh_filename()
>>    block: Do not copy exact_filename from format file
>>    block/nvme: Fix bdrv_refresh_filename()
>>    block/curl: Harmonize option defaults
>>    block/curl: Implement bdrv_refresh_filename()
>>    block/null: Generate filename even with latency-ns
>>    block: BDS options may lack the "driver" option
>>    iotests: Test json:{} filenames of internal BDSs
>>
>>   include/block/block.h         |  16 +-
>>   include/block/block_int.h     |  48 +++-
>>   block.c                       | 505 ++++++++++++++++++++++------------
>>   block/blkdebug.c              |  70 ++---
>>   block/blkverify.c             |  29 +-
>>   block/commit.c                |   3 +-
>>   block/crypto.c                |   8 +
>>   block/curl.c                  |  55 +++-
>>   block/gluster.c               |  19 ++
>>   block/iscsi.c                 |  18 ++
>>   block/mirror.c                |   3 +-
>>   block/nbd.c                   |  46 ++--
>>   block/nfs.c                   |  54 ++--
>>   block/null.c                  |  32 ++-
>>   block/nvme.c                  |  27 +-
>>   block/qapi.c                  |  16 +-
>>   block/qcow.c                  |  14 +-
>>   block/qcow2.c                 |  17 +-
>>   block/qed.c                   |   7 +-
>>   block/quorum.c                |  71 +++--
>>   block/raw-format.c            |  11 +-
>>   block/rbd.c                   |  14 +
>>   block/replication.c           |  10 +-
>>   block/sheepdog.c              |  12 +
>>   block/ssh.c                   |  12 +
>>   block/throttle.c              |   7 +
>>   block/vhdx-log.c              |   1 +
>>   block/vmdk.c                  |  43 ++-
>>   block/vpc.c                   |  11 +-
>>   block/vvfat.c                 |  12 +
>>   block/vxhs.c                  |  11 +
>>   blockdev.c                    |   8 +
>>   qemu-img.c                    |  12 +-
>>   tests/qemu-iotests/051.out    |   8 +-
>>   tests/qemu-iotests/051.pc.out |   8 +-
>>   tests/qemu-iotests/110        |  29 +-
>>   tests/qemu-iotests/110.out    |   9 +-
>>   tests/qemu-iotests/223        | 235 ++++++++++++++++
>>   tests/qemu-iotests/223.out    |  84 ++++++
>>   tests/qemu-iotests/224        | 139 ++++++++++
>>   tests/qemu-iotests/224.out    |  18 ++
>>   tests/qemu-iotests/group      |   2 +
>>   tests/qemu-iotests/iotests.py |  10 +
>>   43 files changed, 1374 insertions(+), 390 deletions(-)
>>   create mode 100755 tests/qemu-iotests/223
>>   create mode 100644 tests/qemu-iotests/223.out
>>   create mode 100755 tests/qemu-iotests/224
>>   create mode 100644 tests/qemu-iotests/224.out
>>
> 
>