Re: [PATCH] files: Use rcu lock to get the file structures for better performance

[Matthew Wilcox]

On Thu, May 21, 2020 at 08:38:35PM +0800, Muchun Song wrote:
> There is another safe way to get the file structure without
> holding the files->file_lock. That is rcu lock, and this way
> has better performance. So use the rcu lock instead of the
> files->file_lock.

What makes you think this is safe?  Are you actually seeing contention
on this spinlock?