Build fix for the LFNIndex merge

Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>
The changes in this commit are related to going back to old getattr, read
and lfn_open() interface. The lfn_open is now using the new IndexManager
::get_index interface and using the CollectionIndex::RWLock to give the
exclusing CollectionIndex* access while write is going on.
Needed to pass one extra boolean to getattr interface to identify the IO
path so that we can get rid of extra attribute name computation.

Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>

Conflicts:
	src/os/FileStore.cc
	src/os/FileStore.h
	src/os/ObjectStore.h
	src/osd/PGBackend.h
	src/osd/ReplicatedBackend.cc
	src/osd/ReplicatedBackend.h
	src/osd/ReplicatedPG.cc
	src/osd/ReplicatedPG.h

Conflict resolved.
Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>
The IndexManager get_index is been modified to take care of a race
condition. Now, Index is not a shared_ptr but a ptr to CollectionIndex*.
We are caching those CollectionIndex* throughout the lifetime of an OSD.
Introduced a RWLock within a Collection Index that will make sure of the
exclusive access in case of write path.

Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>

Conflicts:
	src/os/CollectionIndex.h
	src/os/FlatIndex.cc
	src/os/FlatIndex.h
	src/os/IndexManager.cc
	src/os/IndexManager.h
	src/os/LFNIndex.cc
	src/os/LFNIndex.h

Conflicts resolved.
Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>
FileStore: The sharding FDCache implementation.

Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>