On 06/29/2017 02:59 AM, Vladimir Sementsov-Ogievskiy wrote: > 29.06.2017 03:15, John Snow wrote: >> >> Alright, let me see if I have this straight... >> >> used-data: Normal data. We are standing on terra-firma. >> used-zero: Data that is defined to be zeroes in some way. >> >> (Does not necessarily include data clusters if they were not actually >> zeroed out, I think. May not include regions that ARE zero, even if they >> are literally zero, because the driver may not especially recognize them >> as such. Anything marked as zero will DEFINITELY be zero, though. Yes?) >> >> used-discarded: I'm not actually sure in this case. >> >> used-overrun: Data that is defined to exist, but appears to fall outside >> of or beyond EOF. Appears to happen with qcow2 metadata before any >> writes occur. >> >> unused-data: Normal data, but not in-use by the schema anywhere. Leaked >> clusters and the like, effectively. >> >> unused-zero: Similar to the above, but definitely zeroes. >> >> unused-discarded: Not really sure. > > yes, something like this. again, -data, -zero and -discarded are just > corresponding to return value of bdrv_get_block_status(bs->file), > > if status & BDRV_BLOCK_DATA > it is -data > else if status & BDRV_BLOCK_ZERO > it is -zero (should be holes for raw) > else > it is -discarded (impossible for raw) > end >
Understood, but I was not too clear on the exact nature of block status, so I needed to clarify. I'm a lot clearer now, thanks.