On Tue, Jan 30, 2018 at 10:03:19PM +0200, Amir Goldstein wrote: > On Tue, Jan 30, 2018 at 9:33 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > On Tue, Jan 23, 2018 at 03:47:29PM +0200, Amir Goldstein wrote: > >> On Tue, Jan 23, 2018 at 3:45 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > >> > 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. > >> > > >> > >> OK. so you can get rid of all the middle metacopies while following > >> the origin chain. no reason to keep those. > > > > Hi Amir, > > > > What about the case when we have upper and one middle metacopy. As of top > > most lower is the ORIGIN for upper. Should we retain that top most lower > > ORIGIN as well as lower most data. Or just retain lower most data and > > use that as ORIGIN. > > > > Not sure I follow. > IIUC, the longest possible chain is lowerstack size 2: > upper -> metadata ORIGIN -> data ORIGIN > > If this is what you meant than seems ok to me. Right, that's what I mean. Ok, I will keep it that way. 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
