All quotactl callbacks are done with s_umount held shared. Fine, but ->quota_on() will do kern_path() and _that_ can try to grab the same thing exclusive - suppose we pass a pathname that walks into autofs and triggers mounting of the same fs (at a different mountpoint, that is). That'll end up calling sget(), finding our superblock and trying to grab s_umount on it. mount(8) sits uninterruptibly sleeping in mount(2), kern_path() waits for it to complete and that's not going to happen until the caller of kern_path() (do_quotactl(), ultimately) finishes. Obvious solution is b0rken - we _can't_ take the call of kern_path() to a point prior to getting (and locking) the superblock. Why? Because ocfs2 ignores the pathname argument, so failing on bogus pathnames will blow the userland API compatibility. Other alternatives are also not particulary pleasant since we need s_umount at some point there - we want some exclusion with remounting. Ideas? -- 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
