[PATCH 3/4] dcache: change rename_lock to a sequence read/write lock

The d_path() and related kernel functions currently take a writer lock on rename_lock because they need to follow pointers. By changing rename_lock to be the new sequence read/write lock, a reader lock can be taken and multiple d_path() threads can proceed concurrently without blocking each other.

[PATCH 3/4] dcache: change rename_lock to a sequence read/write lock

The d_path() and related kernel functions currently take a writer lock on rename_lock because they need to follow pointers. By changing rename_lock to be the new sequence read/write lock, a reader lock can be taken and multiple d_path() threads can proceed concurrently without blocking each other.