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Zach Brown
4389c73c14
We've had a long-standing deadlock between lock invalidation and eviction. Invalidating a lock wants to lookup inodes and drop their resources while blocking locks. Eviction wants to get a lock to perform final deletion while the inodes has I_FREEING set which blocks lookups. We only saw this deadlock a handful of times in all of the time we've run the code, but it's now much more common now that we're acquiring locks in iput to test that nlink is zero instead of only when nlink is zero. I see unmount hang regularly when testing final inode deletion. This adds a lookup variant for invalidation which will refuse to return freeing inodes so they won't be waited on. Once they're freeing they can't be seen by future lock users so they don't need to be invalidated. This keeps the lock invalication promise and avoids sleeping on freeing inodes which creates the deadlock. Signed-off-by: Zach Brown <zab@versity.com>