block/qapi: allow best-effort query

For more complex BDS trees that can be created under normal circumstances,
we lose the ability to issue query commands because of our inability to
re-construct the absolute filename.

Instead, omit this field when it is a problem and present as much information
as we can.

This will change the expected output in iotest 110, where we will now see a
json filename and the lack of an absolute filename instead of an error.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1450122916-4706-6-git-send-email-jsnow@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
John Snow 2015-12-14 14:55:16 -05:00 committed by Max Reitz
parent 92d617abc5
commit a5002d5302
2 changed files with 8 additions and 4 deletions

View file

@ -245,10 +245,11 @@ void bdrv_query_image_info(BlockDriverState *bs,
info->has_backing_filename = true; info->has_backing_filename = true;
bdrv_get_full_backing_filename(bs, backing_filename2, PATH_MAX, &err); bdrv_get_full_backing_filename(bs, backing_filename2, PATH_MAX, &err);
if (err) { if (err) {
error_propagate(errp, err); /* Can't reconstruct the full backing filename, so we must omit
qapi_free_ImageInfo(info); * this field and apply a Best Effort to this query. */
g_free(backing_filename2); g_free(backing_filename2);
return; backing_filename2 = NULL;
error_free(err);
} }
/* Always report the full_backing_filename if present, even if it's the /* Always report the full_backing_filename if present, even if it's the

View file

@ -11,7 +11,10 @@ backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
=== Non-reconstructable filename === === Non-reconstructable filename ===
qemu-img: Cannot use relative backing file names for 'json:{"driver": "IMGFMT", "file": {"set-state.0.event": "read_aio", "image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug", "set-state.0.new_state": 42}}' image: json:{"driver": "IMGFMT", "file": {"set-state.0.event": "read_aio", "image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug", "set-state.0.new_state": 42}}
file format: IMGFMT
virtual size: 64M (67108864 bytes)
backing file: t.IMGFMT.base (cannot determine actual path)
=== Backing name is always relative to the backed image === === Backing name is always relative to the backed image ===