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How to ruin Linus's patchHow to ruin Linus's patchPosted Jul 19, 2011 23:18 UTC (Tue) by neilbrown (subscriber, #359)Parent article: How to ruin Linus's vacation
I'm trying to understand Linus' patch.
Moving the assignment to *inode from the start to the end makes lots of sense.
The other mucking about with seqcount doesn't make any sense to me at all.
What exactly is the read_seqcount_retry on path->dentry->d_seq trying to protect? That dentry is the mounted-on dentry so it is pinned and cannot be renamed or deleted.
About the only thing I can think of that might need to be protected against at this point is the mount being unmounted - but if that were the goal of the code I would have expected a comment to that effect, and it doesn't seem like the right place for it anyway..
Any ideas?
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How to ruin Linus's patch Posted Jul 19, 2011 23:47 UTC (Tue) by viro (subscriber, #7872) [Link]
No, you are right - the check is BUG_ON() misspelled. umount *can't* happen
at that point - we are holding vfsmount_lock all the way through RCU walk.
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