• Steven Whitehouse's avatar
    GFS2: Use lockref for glocks · e66cf161
    Steven Whitehouse authored
    Currently glocks have an atomic reference count and also a spinlock
    which covers various internal fields, such as the state. This intent of
    this patch is to replace the spinlock and the atomic reference count
    with a lockref structure. This contains a spinlock which we can continue
    to use as before, and a reference counter which is used in conjuction
    with the spinlock to replace the previous atomic counter.
    
    As a result of this there are some new rules for reference counting on
    glocks. We need to distinguish between reference count changes under
    gl_spin (which are now just increment or decrement of the new counter,
    provided the count cannot hit zero) and those which are outside of
    gl_spin, but which now take gl_spin internally.
    
    The conversion is relatively straight forward. There is probably some
    further clean up which can be done, but the priority at this stage is to
    make the change in as simple a manner as possible.
    
    A consequence of this change is that the reference count is being
    decoupled from the lru list processing. This should allow future
    adoption of the lru_list code with glocks in due course.
    
    The reason for using the "dead" state and not just relying on 0 being
    the "invalid state" is so that in due course 0 ref counts can be
    allowable. The intent is to eventually be able to remove the ref count
    changes which are currently hidden away in state_change().
    Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
    e66cf161
lockref.h 1.23 KB