Excerpts from Christoph Hellwig's message of 2011-04-01 09:34:05 -0400: > On Thu, Mar 31, 2011 at 08:02:22AM -0400, Chris Mason wrote: > > Excerpts from Christoph Hellwig's message of 2011-03-31 02:36:36 -0400: > > > On Thu, Mar 31, 2011 at 12:00:11AM -0400, Larry D'Anna wrote: > > > > This is a simple patch to allow reflinks to be made crossing subvolume > > > > boundaries. > > > > > > NAK. subvolumes will have to become vfsmounts sooner or later, and we > > > really must not support any operations spanning mountpoints. > > > > > > > Sorry, I disagree here. reflinks were always intended to be able to > > span subvolumes. There's no conflict at all because they span different > > inodes. > > I don't think it's a good idea to introduce any user visible operations > over subvolume boundaries. Currently we don't have any operations over > mount boundaries, which is pretty fumdamental to the unix filesystem > semantics. If you want to change this please come up with a clear > description of the semantics and post it to linux-fsdevel for > discussion. That of course requires a clear description of the > btrfs subvolumes, which is still completely missing. >
The subvolume is just a directory tree that can be snapshotted, and has it's own private inode number space. reflink across subvolumes is no different from copying a file from one subvolume to another at the VFS level. The src and destination are different files and different inodes, they just happen to share data extents. -chris -- 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
