Miklos Szeredi: > For example "rmdir /ovl/a/b" will do the following: > > 1. find the underlying dentry for "a" -> upper-a > 2. lock upper-a > 3. find the underlying dentry for "b" -> upper-b > 4. verify that upper-b is a child of upper-a > 5. remove upper-b It is good to verify in step 4. Essentially (or ideally) this verification should be equivalent to all of what VFS does before vfs_rmdir(). I know overlayfs makes the upper mnt_want_write()-ed in early stage and keeps it. So it might be better to lookup again (as step 3 and 4) instead of comparing d_parent simply. If you think it is unnecessary to lookup here, then I'd suggest you to make it option (choosable by user). I see ovl_rmdir() does, - lookup and unlink all whiteouts - rmdir the target dir - create a whiteout for the target Right? But I am afraid that any error can happen in every step on the upper dir. And if it happens, then ovl_rmdir() returns the error but the dir left in incomplete status. It may be one of these. - some whiteouts are unlinked but others are left - all whiteouts are gone but the target dir remains - the target dir is removed but the whiteout is not created Of course, it is bad and makes users really confused, since it will show users things which should not be. At the same time, I don't know how possible it can happen. Anyway if you have read aufs, then you would know how aufs solves these problems. I don't think the approaches in aufs is best or one and only. I just could not get another good idea. J. R. Okajima -- 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
