"J. R. Okajima" <hooanon05@xxxxxxxxxxx> writes: > Miklos Szeredi: >> st_nlink==1 for directories is widely accepted way of saying that the >> number of subdirectories is unknown. Various filesystems already do >> this, and versions of GNU utils that I have come across accept it. > > When the upperdir is tmpfs, the link count of the directories in it will > not be 1, won't it? In overlayfs directory will have a link count of one if it's a "merged" directory, regardless of the filesystem types used. If it's not a merged directory, then st_nlink will correctly refrect the number of subdirs. >> I hadn't thought about this case, so overlayfs would modify the lower >> filesystem in that case, which is a no-no. >> >> Following patch fixes this and return -EROFS for the above case. I also >> updated the non-standard section in the docs. > > Hmm, such changes to mnt_flags looks slightly rude to me. Do we have to > consider about these? > - there may exist files opened as RW on the lower. > - when overlayfs is unmounted, it should restore the original mnt_flags. > - (there may exist more...) > > If overlayfs doesn't expect the lower mounted as RW, then it might be > better to reject it simply at mounting. Overlayfs will create a private clone of both the lower and upper mounts. The mnt_flags are only modified on the private clone, whose sole user is overlayfs itself. Thanks, Miklos -- 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
