Messages in this thread | | | Date | Sat, 16 Oct 2010 20:47:10 -0400 | From | Christoph Hellwig <> | Subject | Re: [PATCH 04/19] fs: Implement lazy LRU updates for inodes. |
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On Sun, Oct 17, 2010 at 04:29:24AM +1100, Nick Piggin wrote: > > I don't think the pointer check will work either. By the time we retake > > the lru lock the inode might already have been reaped through a call > > to invalidate_inodes. There's no way we can do anything with it after > > I don't think you're right. If we re take inode_lock, ensure it is on > the LRU, and call the can_unuse checks, there is no more problem than > the regular loop taking items from the LRU, AFAIKS.
As long as we have the global inode lock it should indeed be safe. But once we have a separate lru lock (global or per-zone, with or without i_lock during the addition) there is nothing preventing the inode from getting reused and re-added to the lru in the meantime. Sure this is an extremly unlikely case, but there is no locking to prevent it once inode_lock is gone.
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