Re: [Qemu-devel] [PATCH v2 0/5] block: Relative backing files

[Max Reitz <mreitz@redhat.com>]

On 2014-11-04 at 15:19, Max Reitz wrote:
> Technically, this is a v2 to my previous series
> "block: JSON filenames and relative backing files", although only patch
> 2 and 5 were already part of that series, and also patch 2 has been
> changed quite a bit in this version.
>
> So, first the original cover letter:
>
> 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.
>
> And now about why this v2 exists:
>
> 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 4 of this v2 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 3.
>
> 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 1. Patch 2 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 5 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).
>
>
> Max Reitz (5):
>    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                    | 50 ++++++++++++++++++------
>   block/qapi.c               |  7 +++-
>   block/vmdk.c               | 13 ++++++-
>   include/block/block.h      |  6 ++-
>   tests/qemu-iotests/110     | 94 ++++++++++++++++++++++++++++++++++++++++++++++
>   tests/qemu-iotests/110.out | 19 ++++++++++
>   tests/qemu-iotests/group   |  1 +
>   7 files changed, 176 insertions(+), 14 deletions(-)
>   create mode 100755 tests/qemu-iotests/110
>   create mode 100644 tests/qemu-iotests/110.out

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