Re: [Qemu-devel] [PATCH v4 0/6] block: Relative backing files

[Max Reitz <mreitz@redhat.com>]

On 2014-11-26 at 17:20, Max Reitz wrote:
> Cover letter of v1:
>
> Sometimes, qemu does not have a filename to work with (it then generates
> a JSON filename), so it does not know which directory to use for a
> backing file specified by a relative filename.
>
> In this case, qemu should not somehow try to append the backing file's
> name to the JSON object, but rather just print an error and bail out.
>
>
> Part of the cover letter specific to v2 (with patch numbers fixed):
>
> Stefan already applied v1 before realizing that the test added in the
> series was actually broken for vmdk (which I somehow missed myself).
> This was due to vmdk trying to open the backing file on creation in
> order to determine its format; however, normally the backing file path
> is interpreted relatively to the backed image's base directory, whereas
> in this case vmdk directly used the user-specified filename which was
> therefore interpreted relatively to qemu's working directory.
>
> Patch 5 of this v2 (v4) fixes this. A similar issue exists directly in
> bdrv_img_create() which opens the backing file in order to determine its
> size in case the size of the new image has not been specified. This is
> fixed by patch 4.
>
> The function both patches use is factored out from
> bdrv_get_full_backing_filename() (which we cannot use here because it
> requires a BDS which does not necessarily exist during image creation)
> in patch 2. Patch 3 was then modified so it modifies this new function
> (bdrv_get_full_backing_filename_from_filename()) and the old
> bdrv_get_full_backing_filename(), which is now more or less just a
> wrapper.
>
> And finally, I added a test to patch 6 which tests creation of a backed
> image in another directory only using relative paths while omitting the
> image size (which is therefore inferred from the backing file).
>
>
> v4:
> - Added patch 1: Patch 3 (prev. 2) failed checkpatch.pl, so do the
>    obvious: Fix checkpatch.pl.
> - Patch 3 (prev. 2): Fix overly long line [Fam]
> - Patch 6 (prev. 5): s/shoud/should/ [Eric]
>
>
> git-backport-diff against v3:
>
> 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
>
> 001/6:[down] 'checkpatch: Brace handling on multi-line condition'
> 002/6:[----] [--] 'block: Get full backing filename from string'
> 003/6:[0003] [FC] 'block: JSON filenames and relative backing files'
> 004/6:[----] [--] 'block: Relative backing file for image creation'
> 005/6:[----] [--] 'block/vmdk: Relative backing file for creation'
> 006/6:[0002] [FC] 'iotests: Add test for relative backing file names'
>
>
> Max Reitz (6):
>    checkpatch: Brace handling on multi-line condition
>    block: Get full backing filename from string
>    block: JSON filenames and relative backing files
>    block: Relative backing file for image creation
>    block/vmdk: Relative backing file for creation
>    iotests: Add test for relative backing file names
>
>   block.c                    | 46 ++++++++++++++++++++---
>   block/qapi.c               |  7 +++-
>   block/vmdk.c               | 13 ++++++-
>   include/block/block.h      |  6 ++-
>   scripts/checkpatch.pl      | 13 ++++++-
>   tests/qemu-iotests/110     | 94 ++++++++++++++++++++++++++++++++++++++++++++++
>   tests/qemu-iotests/110.out | 19 ++++++++++
>   tests/qemu-iotests/group   |  1 +
>   8 files changed, 188 insertions(+), 11 deletions(-)
>   create mode 100755 tests/qemu-iotests/110
>   create mode 100644 tests/qemu-iotests/110.out

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