On Fri, Jun 11, 2021 at 10:03 PM Eric Blake <ebl...@redhat.com> wrote: > > To save the user from having to check 'qemu-img info --backing-chain' > or other followup command to determine which "depth":n goes beyond the > chain, add a boolean field "backing" that is set only for unallocated > portions of the disk. > > Signed-off-by: Eric Blake <ebl...@redhat.com> > --- > > Touches the same iotest output as 1/1. If we decide that switching to > "depth":n+1 is too risky, and that the mere addition of "backing":true > while keeping "depth":n is good enough, then we'd have just one patch, > instead of this double churn. Preferences? > > docs/tools/qemu-img.rst | 3 ++ > qapi/block-core.json | 7 ++- > qemu-img.c | 15 +++++- > tests/qemu-iotests/122.out | 34 +++++++------- > tests/qemu-iotests/154.out | 96 +++++++++++++++++++------------------- > tests/qemu-iotests/179.out | 66 +++++++++++++------------- > tests/qemu-iotests/223.out | 24 +++++----- > tests/qemu-iotests/244.out | 6 +-- > tests/qemu-iotests/252.out | 4 +- > tests/qemu-iotests/274.out | 16 +++---- > tests/qemu-iotests/291.out | 8 ++-- > tests/qemu-iotests/309.out | 4 +- > 12 files changed, 150 insertions(+), 133 deletions(-) > > diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst > index c155b1bf3cc8..fbc623b645c3 100644 > --- a/docs/tools/qemu-img.rst > +++ b/docs/tools/qemu-img.rst > @@ -601,6 +601,9 @@ Command description: > a ``depth``; for example, a depth of 2 refers to the backing file > of the backing file of *FILENAME*. Depth will be one larger than > the chain length if no file in the chain provides the data. > + - an optional ``backing`` field is present with value true if no > + file in the backing chain provides the data (making it easier to > + identify when ``depth`` exceeds the chain length). > > In JSON format, the ``offset`` field is optional; it is absent in > cases where ``human`` format would omit the entry or exit with an error. > diff --git a/qapi/block-core.json b/qapi/block-core.json > index 2ea294129e08..cebe12ba16a0 100644 > --- a/qapi/block-core.json > +++ b/qapi/block-core.json > @@ -264,6 +264,9 @@ > # @offset: if present, the image file stores the data for this range > # in raw format at the given (host) offset > # > +# @backing: if present, the range is not allocated within the backing > +# chain (since 6.1) > +# > # @filename: filename that is referred to by @offset > # > # Since: 2.6 > @@ -271,8 +274,8 @@ > ## > { 'struct': 'MapEntry', > 'data': {'start': 'int', 'length': 'int', 'data': 'bool', > - 'zero': 'bool', 'depth': 'int', '*offset': 'int', > - '*filename': 'str' } } > + 'zero': 'bool', 'depth': 'int', '*backing': 'bool', > + '*offset': 'int', '*filename': 'str' } } > > ## > # @BlockdevCacheInfo: > diff --git a/qemu-img.c b/qemu-img.c > index 33a5cd012b8b..4d357f534803 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -2977,8 +2977,13 @@ static int dump_map_entry(OutputFormat output_format, > MapEntry *e, > break; > case OFORMAT_JSON: > printf("{ \"start\": %"PRId64", \"length\": %"PRId64"," > - " \"depth\": %"PRId64", \"zero\": %s, \"data\": %s", > - e->start, e->length, e->depth, > + " \"depth\": %"PRId64, e->start, e->length, e->depth); > + if (e->has_backing) { > + /* Backing should only be set at the end of the chain */ > + assert(e->backing && e->depth > 0); > + printf(", \"backing\": true"); > + }
It will be easier to inspect the output if common fields come before optional fields. > + printf(", \"zero\": %s, \"data\": %s", > e->zero ? "true" : "false", > e->data ? "true" : "false"); > if (e->has_offset) { ... > diff --git a/tests/qemu-iotests/122.out b/tests/qemu-iotests/122.out > index 779dab4847f0..c5aa2c9866f1 100644 > --- a/tests/qemu-iotests/122.out > +++ b/tests/qemu-iotests/122.out > @@ -68,11 +68,11 @@ read 65536/65536 bytes at offset 4194304 > read 65536/65536 bytes at offset 8388608 > 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > [{ "start": 0, "length": 65536, "depth": 0, "zero": false, "data": true}, > -{ "start": 65536, "length": 4128768, "depth": 1, "zero": true, "data": > false}, > +{ "start": 65536, "length": 4128768, "depth": 1, "backing": true, "zero": > true, "data": false}, So this output would be: [{ "start": 0, "length": 65536, "depth": 0, "zero": false, "data": true}, { "start": 65536, "length": 4128768, "depth": 1, "zero": true, "data": false, "backing": true},