On Wed, Oct 31, 2012 at 10:30:22AM +0800, Jeff Liu wrote: > One idea is to mark those cloned extents as FIEMAP_EXTENT_SHARED so that > we can go through a file to figure out how many extents are shared > through fiemap(2), and calculate the real storage(fs/subvolume) footprint > in the end.
This will cost at least one more seek per extent to find out that the extent is shared, could be quite expensive. And without any possibility to turn this off, I'm afraid this will render FIEMAP unusable in practice. david -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
