ocfs2: support for removing file regions

Provide an internal interface for the removal of arbitrary file regions.

ocfs2_remove_inode_range() takes a byte range within a file and will remove
existing extents within that range. Partial clusters will be zeroed so that
any read from within the region will return zeros.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

diff --cc fs/ocfs2/alloc.c
Simple merge

diff --cc fs/ocfs2/alloc.h
Simple merge

diff --cc fs/ocfs2/file.c
Simple merge

diff --cc fs/ocfs2/journal.h
Simple merge