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? > > - If I remember correctly, Valerie Aurora has pointed out that > > open(O_RDONLY) + fchmod() will work correctly in UnionMount. > > It is true in overlayfs too? > > Neither union-mounts nor overlayfs can handle this case. Oh, I meant "will work NOT correctly". Sorry. > 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. 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
