On 2011-04-15, at 6:50 PM, Dave Chinner <[email protected]> wrote: > What you are suggesting is that FIEMAP needs to be page cache > coherent, and that is far, far away from the intended use of the > interface. Even consiering that you need to looking for active pages > in the page cache when mapping extents say to me that you are > doing something very wrong. > > Unwritten extents remain unwritten until the data is physically > written to them. Therefore, to change their state, you need to sync > the data covering the range.
In that case, it means cp should just always use FIEMAP_FLAG_SYNC, which is fine. Cheers, Andreas
