Re: [PATCH 3/6] mirror: Skip writing zeroes when target is already zero

[Vladimir Sementsov-Ogievskiy]

On 17.04.25 00:51, Eric Blake wrote:
> (a write zeroes that fails AND causes the disk to no longer read as
> zero should not happen)

I don't know, is there such a contract? write-zeroes may fallback to write(), 
which only state that:

       An error return value while performing write() using direct I/O
       does not mean the entire write has failed.  Partial data may be
       written and the data at the file offset on which the write() was
       attempted should be considered inconsistent.

So, I used to think that on failed write nothing is guaranteed.

What do we lose if we just unset the bitmap before write-zeroes, and set it 
again in case of success?

--
Best regards,
Vladimir