On Monday 27 September 2010 20:47:47 Valerie Aurora wrote: > Maybe I don't understand. It seems like directories created when the > file system is *not* union mounted should definitely be merged with > matching directories on the lower layer. > > Take the case of /etc/fstab. The first union mount never touches /etc > and it doesn't exist on the topmost layer. Then we unmount the upper > layer, mount it somewhere else as a plain mount, and create /etc/ and > /etc/fstab. When we union mount it back over the lower layer again, > we still want the lower layer /etc/ to be merged with the topmost > /etc/, or else init.d will disappear. I can't think of a reason why the upper layer would really *need* to be modified separately as in this example though, and I'm sure that examples for opaqueness by default can be constructed as well. Transparency comes at a cost though (lookup, readdir, whiteouts), and defaulting to opaque directories will be more efficient in some cases. This is why I think that opaqueness by default is preferable. > Again, maybe I'm misunderstanding, but this doesn't make much sense to > me. Say I create: > > /upper/a_dir/upper_file > /lower/a_dir/lower_file > > Then when I union mount them, I want a_dir/ to be transparent > automatically and show both upper_file and lower_file, without marking > it manually. Why? Thanks, Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
