Christoph Hellwig <hch@xxxxxx> wrote: > We'll you'd need to implement a IOCB_NOHOLE, but that wouldn't be all > that hard. Having a READ_PLUS like interface that actually tells you > how large the hole is might be hard. Actually, that raises another couple of questions: (1) Is a filesystem allowed to join up two disjoint blocks of data with a block of zeros to make a single extent? If this happens, I'll see the inserted block of zeros to be valid data. (2) Is a filesystem allowed to punch out a block of valid zero data to make a hole? This would cause me to refetch the data. David