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Date: Tue, 10 Mar 2015 17:29:18 +0300
From: "Denis V. Lunev" <den@openvz.org>
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Subject: Re: [Qemu-devel] [PATCH 18/27] block/parallels: implement
 parallels_check method of block driver
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To: Roman Kagan <rkagan@parallels.com>, Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>

On 10/03/15 17:24, Roman Kagan wrote:
> On Tue, Mar 10, 2015 at 11:51:12AM +0300, Denis V. Lunev wrote:
>> The check is very simple at the moment. It calculates necessary stats
>> and fix only the following errors:
>> - space leak at the end of the image. This would happens due to
>>    preallocation
>> - clusters outside the image are zeroed. Nothing else could be done here
>>
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> CC: Roman Kagan <rkagan@parallels.com>
>> CC: Kevin Wolf <kwolf@redhat.com>
>> CC: Stefan Hajnoczi <stefanha@redhat.com>
>> ---
>>   block/parallels.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 82 insertions(+)
>>
>> diff --git a/block/parallels.c b/block/parallels.c
>> index 65f6418..e5b475e 100644
>> --- a/block/parallels.c
>> +++ b/block/parallels.c
>> @@ -228,6 +228,87 @@ fail:
>>       return ret;
>>   }
>>   
>> +
>> +static int parallels_check(BlockDriverState *bs, BdrvCheckResult *res,
>> +                           BdrvCheckMode fix)
>> +{
>> +    BDRVParallelsState *s = bs->opaque;
>> +    int64_t size, prev_off, high_off;
>> +    int ret;
>> +    uint32_t i;
>> +    bool flush_bat = false;
>> +    int cluster_size = s->tracks << BDRV_SECTOR_BITS;
>> +
>> +    size = bdrv_getlength(bs->file);
>> +    if (size < 0) {
>> +        res->check_errors++;
>> +        return size;
>> +    }
>> +
>> +    res->bfi.total_clusters = s->bat_size;
>> +    res->bfi.compressed_clusters = 0; /* compression is not supported */
>> +
>> +    high_off = 0;
>> +    prev_off = 0;
>> +    for (i = 0; i < s->bat_size; i++) {
>> +        int64_t off = bat2sect(s, i) << BDRV_SECTOR_BITS;
>> +        if (off == 0)
>> +            continue;
> If you don't update prev_off here you can get fragmentation stats wrong
> (dunno how important it is)

ok. by the way, I have missed braces here...

>> +
>> +        /* cluster outside the image */
>> +        if (off > size) {
>> +            fprintf(stderr, "%s cluster %u is outside image\n",
>> +                    fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i);
>> +            res->corruptions++;
>> +            if (fix & BDRV_FIX_ERRORS) {
>> +                s->bat_bitmap[i] = 0;
>> +                res->corruptions_fixed++;
>> +                flush_bat = true;
>> +                continue;
>> +            }
> Ditto
>
> Roman.