MDS: switch cache object classes to use MutationRef instead of raw pointers

Signed-off-by: Greg Farnum <greg@inktank.com>
Server: use MutationRef instead of raw pointer

Signed-off-by: Greg Farnum <greg@inktank.com>
MDCache: use MutationRef instead of raw pointers

Signed-off-by: Greg Farnum <greg@inktank.com>
MDCache: use a null_ref instead of NULL in a few places

Signed-off-by: Greg Farnum <greg@inktank.com>
MDCache: fix users of active_requests for use of shared_ptr

Signed-off-by: Greg Farnum <greg@inktank.com>
Locker: remove Mutation param from xlock_import

It's not used.

Signed-off-by: Greg Farnum <greg@inktank.com>
Locker: Use MutationRef instead of raw pointers

Signed-off-by: Greg Farnum <greg@inktank.com>
Locker: use a null_ref instead of NULL

Signed-off-by: Greg Farnum <greg@inktank.com>
Locker: use raw MutationImpl* instead of MutationRef in several places

Sadly, you can't implicitly convert non-const references to shared pointers, so avoid the atomic ops necessary when copying a shared_ptr.

Signed-off-by: Greg Farnum <greg@inktank.com>
MDCache: use raw MutationImpl* instead of MutationRef in a few places

Avoid the atomic ops necessary when copying a shared_ptr.

Signed-off-by: Greg Farnum <greg@inktank.com>
SimpleLock: Switch MutationRef& for MutationRef in get_xlock()

Signed-off-by: Greg Farnum <greg@inktank.com>