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7214e8600e
Once we remove the client_mutex, there's an unlikely but possible race that could occur. It will be possible for nfs4_file_put_access to race with nfs4_file_get_access. The refcount will go to zero (briefly) and then bumped back to one. If that happens we set ourselves up for a use-after-free and the potential for a lock to race onto the i_flock list as a filp is being torn down. Ensure that we can safely bump the refcount on the file by holding the fi_lock whenever that's done. The only place it currently isn't is in get_lock_access. In order to ensure atomicity with finding the file, use the find_*_file_locked variants and then call get_lock_access to get new access references on the nfs4_file under the same lock. Signed-off-by: Jeff Layton <jlayton@primarydata.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>