Messages in this thread | | | From | "J. R. Okajima" <> | Subject | Re: [PATCH 0/7] overlay filesystem: request for inclusion | Date | Fri, 15 Jul 2011 22:02:08 +0900 |
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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
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