On Mon, Jan 22, 2018 at 09:46:33PM +0200, Amir Goldstein wrote: > On Mon, Jan 22, 2018 at 9:34 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > On Mon, Jan 22, 2018 at 8:39 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > >> There is a need to support metacopy dentry in midlayer. That means there > >> could be a chain of metacopy dentries. > >> > >> For example, upper could be metacopy, midlayer lower could be metacopy and > >> lowest layer could be actual data inode. This means when we copy up actual > >> data, we should be able to reach to lowest data inode and copy up data from > >> there. And that means we should keep track of all the dentries in origin > >> chain which lead to data inode. > >> > >> Current ovl_check_origin() logic only looks for one origin dentry. This patch > >> enhances ovl_check_origin() to continue to follow origin chain and return > >> all the origin entries found. This is done only if caller of the function > >> set "follow_chain" argument. > >> > > > > We don't really need to keep the entire chain do we? > > We can follow chain but keep only the one inode that is not a metacopy inode. > > All the rest are useless, no? > > Then we don't create a new type of object - non-dir with numlower > 1. > > > > Seems like if you don't keep the entire chain, then no need for > patches 14 and 15. I will need to have atleast 2 lower dentries. One will be top most metadata copy and other lower most data dentry. IOW, both the ends of the chain need to be there. > Also with upper metacopy, you can fix upper origin xattr after > following to the data > origin and forget about middle layer metacopies forever. If upper metacopy is alreday there, then I agree that lower top most becomes inner node of chain and we can get rid of it. > > Am I missing something? I think you are missing the case when there is no upper and lower has a metacopy chain. In that case we need to retain two dentries. One for data copy up and one for metadata copy up. Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
