On Wed, Mar 25, 2015 at 07:38:20AM -0400, Rich Freeman wrote: > On Wed, Mar 25, 2015 at 6:55 AM, Marc Cousin <cousinmarc@xxxxxxxxx> wrote: > > On 25/03/2015 02:19, David Sterba wrote: > >> as it reads the pre/post snapshots and deletes them if the diff is > >> empty. This adds some IO stress. > > > > I couldn't find a clear explanation in the documentation. Does it mean > > that when there is absolutely no difference between two snapshots, one > > of them is deleted ? And that snapper does a diff between them to > > determine that ? > > > > It seems like there should be some supported way of doing a diff on > two btrfs subvolumes. > The problem is that we don't have any functionality in kernel space to > do this (that I'm aware of), and we don't expose the necessary > information to userspace for it to do this smartly (again, as far as > I'm aware). > Maybe there would be some way to do it using btrfs send and parsing the output. If the subvolumes are read-only than the lightweight send (ioctl with flag bit set BTRFS_SEND_FLAG_NO_FILE_DATA) could be used and I think this was the expected usecase. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
