On Fri, Mar 9, 2018 at 6:30 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > On Fri, Mar 09, 2018 at 05:20:30PM +0200, Amir Goldstein wrote: >> On Fri, Mar 9, 2018 at 4:44 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: >> > On Fri, Mar 09, 2018 at 12:34:57AM +0200, Amir Goldstein wrote: >> >> On Fri, Mar 9, 2018 at 12:18 AM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: >> >> > Certain properties in ovl_lookup_data should be set only for the last >> >> > element of the path. IOW, of we are calling ovl_lookup_single() for an >> >> > absolute redirect, then d->is_dir and d->opaque do not make much sense >> >> > for intermediate path elements. Instead set them only if dentry being >> >> > lookup is last path element. >> >> >> >> Yeh, that's what I said, but I realized later that this is not accurate. >> >> it's true for d->is_dir, but not true for d->opaque. >> >> opaqueness of path elements *can* determine that the redirect result is >> >> opaque, for example when redirecting to /a/b/c and /a is opaque, then >> >> the resolved redirection is opaque *unless* either /a/b or /a/b/c has >> >> an absolute redirect to escape the opaqueness of /a. >> > >> > Hi Amir, >> > >> > I am not sure I understand this argument about "opaque". Why opaqueness >> > of parent matters to child. Can you please give an example. >> > >> >> upper: /redirect (redirect=/a/b/c) >> lower1: /a/[b]/c ([b] is opaque) >> lower0: /a/b/c/foo >> >> upper /redirect was created by 'mv /mnt/a/b/c/ /mnt/redirect' >> before rename /mnt/a/b/c did not contain 'foo' because /mnt/a/b >> is not a merge dir and therefore neither is /mnt/a/b/c. >> after rename /redirect should not contain 'foo' as well. >> This is handles by ovl_lookup_layer() when iterating absolute >> redirect element [b] d->opaque is set in the lookup state. >> >> The fix I sent for the case where /a/[b]/c is again an absolute >> redirect (say to /a/b/c in lower0) and that *should* results in >> the merge dir containing 'foo'. >> >> Not easy... > > Aha.., I get it now. So I have couple of observations. > > - d->opaque is still seems to be the property of last element we are > searching in the path. It is d->stop which should get set for > intermediate elements if we find an opaque dir in the path. > > In fact, ovl_lookup() does not even look at d->opaque until and unless > it is set on upperdentry. Right? > > So if we don't set d->opaque on a lower dentry, looks like nobody will > care as of now. But just to define semantics right, we can say d->opaque > represents the property of last element of the path. > > - And apply your patch on top which will just reset d->stop = false if > an absolute redirect was found in the path and leave d->opaque > untouched. > > Does it make sense? > Yeh, ok. I guess d->stop is sufficient. You may take my patch and modify it if you like. Thanks, Amir. -- 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
