Saket Sinha: > > For such purpose, a "block device level union" (instead of filesystem > > level union) may be an option for you, such as "dm snapshot". > > > I imagine that this would make things more complicated as ideally this > should be done in a filesystem driver. Again a "block device level > union" would all the more have lesser chances of getting this > filesystem driver included in the mainline kernel as kernel > maintainers prefer the drivers to be as simple as possible. ?? I am afraid that I cannot fully understand what you wrote. If you think "dm snapshot" does not exist currently, and you or someone else are going to develop a new feature, that is wrong. You already have "dm snapshot" feature and you can "stack" the block devices by using it. (cf. http://aufs.sourceforge.net/aufs2/report/sq/sq.pdf which is a bit old) J. R. Okajima -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>