ceph: fix memory leak in ceph_direct_read_write()

ceph: fix memory leak in ceph_direct_read_write()

The bvecs array which is allocated in iter_get_bvecs_alloc() is leaked
and pages remain pinned if ceph_alloc_sparse_ext_map() fails.

There is no need to delay the allocation of sparse_ext map until after
the bvecs array is set up, so fix this by moving sparse_ext allocation
a bit earlier.  Also, make a similar adjustment in __ceph_sync_read()
for consistency (a leak of the same kind in __ceph_sync_read() has been
addressed differently).

Cc: stable@vger.kernel.org
Fixes: 03bc06c7b0bd ("ceph: add new mount option to enable sparse reads")
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Alex Markuze <amarkuze@redhat.com>