On Fri, Oct 11, 2019 at 05:55:22AM -0700, Christoph Hellwig wrote: > On Wed, Oct 09, 2019 at 02:21:23PM +1100, Dave Chinner wrote: > > @@ -131,6 +132,7 @@ xfs_inode_free( > > * free state. The ip->i_flags_lock provides the barrier against lookup > > * races. > > */ > > + xfs_ilock(ip, XFS_ILOCK_EXCL); > > This introduceѕ a non-owner unlock of an exclusively held rwsem. As-is > this will make lockdep very unhappy. We have a non-owner unlock version > of up_read, but not of up_write currently. I'm also not sure if those > are allowed from RCU callback, which IIRC can run from softirq context. > > That being said this scheme of only unlocking the inode in the rcu free > callback makes totaly sense to me, so I wish we can accomodate it > somehow. I'm thinking that, barring the little issue of not actually having the function, up_write_non_owner() should work from RCU callback context. That is, I don't see rwsem_wake() do anything not allowed there.
