On 2017/12/15 15:23, Amir Goldstein Wrote: > On Fri, Dec 15, 2017 at 8:42 AM, zhangyi (F) <yi.zhang@xxxxxxxxxx> wrote: >> On 2017/12/14 21:44, Amir Goldstein Wrote: >>> On Thu, Dec 14, 2017 at 8:48 AM, zhangyi (F) <yi.zhang@xxxxxxxxxx> wrote: > [...] >>> Please test the Valid "rename exchange redirect" case: >>> set_redirect $upperdir/testdir1 "testdir2" >>> set_redirect $upperdir/testdir2 "testdir1" >>> fsck should not remove those redirects. >>> >> I can add this case. I was wondering why add this special one? If I understand right, >> these two xattrs will not remove after fsck if $lowerdir/testdir1 and $lowerdir/testdir2 >> exists, just like the second test case "Test valid redirect xattr point to a directory >> origin in the same directory". >> > > IIUC, the first version of fsck you posted wanted to make sure that > origin is covered with either a whiteout or opaque dir and I commented > that it is also legal to be covered by a redirected dir. > So the test of exchanged redirect dirs checks that this condition is handled > correctly by fsck. > Understand, will add. [..] > That is one way of getting to that inconsistency which suggests that the correct > and automatic fix is to set opaque on uper/testdir, but what about: > > 1) extract pre-defined image to lower/testdir upper/testdir > 2) mount overlay > 3) mv merge/testdir merge/dir2 (will create an whiteout 'testdir' in upper) > 4) mkdir merge/testdir (create opaque dir) > 5) umount overlay > 6) re-extract pre-defined image to lower/testdir upper/testdir (*) > > (*) Anything that *can* happen *will* happen... > > Note that prior to redirect_dir feature, use could even get a way with this > partial restore/undo of testdir changes. > > My point is that if you have 2 dirs pointing at the same lower, either > because they are both redirect or because one is not opaque, it is > not possible to automatically determine which should be the merge dir > and need to ask user to resolve the conflict. > I think I follow you now, this does verly likly to happen. Will handle this case to ask user in default mode, do nothing in auto and yes mode. [..] >> Let me see, now, fsck will remove the *later redirect xattr in 'yes' mode, >> which means that we guess user want to copy the tree in upperdir if they >> call cp -a when overlayfs is offline, not the whole tree expose in merge >> layer. I think if we need to copy whole tree include lower dirs maybe too >> complicated. >> >> *) fsck just remove the later one when scaning, I understand it maybe cannot guaranty >> fsck will clears testdir1 and not testdir2 for some base filesystem, so need to find >> better way, thoughts? >> > > quite simple I think. Instead of verifying that redirect was removed > from testdir1 > and remained on testdir2, verify that redirect from removed from either and > left on exactly one of them. Less trivial scripting, but not impossible. > Yes, will do. Thanks a lot, Yi -- 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
