Re: [Qemu-devel] [PATCH v9 1/2] qemu-img info lists bitmap directory entries

[Andrey Shinkevich]

>>
>> diff --git a/block/qapi.c b/block/qapi.c
>> index c66f949..0fde98c 100644
>> --- a/block/qapi.c
>> +++ b/block/qapi.c
>> @@ -38,6 +38,7 @@
>>   #include "qapi/qmp/qstring.h"
>>   #include "sysemu/block-backend.h"
>>   #include "qemu/cutils.h"
>> +#include "qemu/error-report.h"
>>   
>>   BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
>>                                           BlockDriverState *bs, Error **errp)
>> @@ -868,6 +869,11 @@ void bdrv_image_info_dump(fprintf_function 
>> func_fprintf, void *f,
>>   
>>       if (info->has_format_specific) {
>>           func_fprintf(f, "Format specific information:\n");
>> +        if (info->format_specific &&
>> +            info->format_specific->type == IMAGE_INFO_SPECIFIC_KIND_QCOW2 &&
>> +            info->format_specific->u.qcow2.data->has_bitmaps == false) {
>> +            warn_report("Failed to load bitmap list");
>> +        }
>>           bdrv_image_info_specific_dump(func_fprintf, f, 
>> info->format_specific);
>>       }
>>   }
> 
> Is it really necessary to introduce qcow2 specific knowledge in
> block/qapi.c (where it definitely doesn't belong), just to emit a
> warning?
> 
> Why can't you print the warning in qcow2_get_specific_info()?

Dear Kevin,
The reason behind the idea to move the warning to qapi is that we 
wouldn't like to print that in case of JSON format.

> 
>> diff --git a/block/qcow2.c b/block/qcow2.c
>> index 4897aba..07b99ee 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -4386,8 +4386,14 @@ static ImageInfoSpecific 
>> *qcow2_get_specific_info(BlockDriverState *bs)
>>           *spec_info->u.qcow2.data = (ImageInfoSpecificQCow2){
>>               .compat             = g_strdup("0.10"),
>>               .refcount_bits      = s->refcount_bits,
>> +            .has_bitmaps        = true, /* To handle error check properly */
>> +            .bitmaps            = NULL, /* Unsupported for version 2 */
> 
> .has_bitmaps = false would be nicer if the format doesn't even support
> bitmaps. You only need this here because you put the warning in the
> wrong place.
> 
>>           };
>>       } else if (s->qcow_version == 3) {
>> +        Qcow2BitmapInfoList *bitmaps;
>> +        Error *local_err = NULL;
>> +
>> +        bitmaps = qcow2_get_bitmap_info_list(bs, &local_err);
> 
> Here you even had a good error message to print...
> 
>>           *spec_info->u.qcow2.data = (ImageInfoSpecificQCow2){
>>               .compat             = g_strdup("1.1"),
>>               .lazy_refcounts     = s->compatible_features &
>> @@ -4397,7 +4403,14 @@ static ImageInfoSpecific 
>> *qcow2_get_specific_info(BlockDriverState *bs)
>>                                     QCOW2_INCOMPAT_CORRUPT,
>>               .has_corrupt        = true,
>>               .refcount_bits      = s->refcount_bits,
>> +            .has_bitmaps        = !local_err,
>> +            .bitmaps            = bitmaps,
>>           };
>> +        /*
>> +         * If an error occurs in obtaining bitmaps, ignore
>> +         * it to show other QCOW2 specific information.
>> +         */
>> +        error_free(local_err);
> 
> ...but you decided to discard it.
> 
> How about you do this here:
> 
>      warn_reportf_err(local_err, "Failed to load bitmap list: ");

In case of JSON format, we can fail here.
It will happen in the current implementation of the new test #239.

> 
> And then get rid of the code in block/qapi.c and the version 2 path?
> 
> Actually, should this really only be a warning, or in fact an error?
> What's the case where we expect that loading the bitmap list can fail,
> but the management tool doesn't need to know that and we just want to
> log a message?
> 
>>       } else {
>>           /* if this assertion fails, this probably means a new version was
>>            * added without having it covered here */
> 
> Kevin
> 

-- 
With the best regards,
Andrey Shinkevich