osd/Replicated: For CEPH_OSD_OP_WRITE, set data digest.

Add two cases which can add data digest for OP_WRITE:
a: offset = 0, and length > original size
b: offset = original size, and original has data_digest.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>

src/osd/ReplicatedPG.cc

@@ -4385,8 +4385,10 @@ int ReplicatedPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
 	write_update_size_and_usage(ctx->delta_stats, oi, ctx->modified_ranges,
 				    op.extent.offset, op.extent.length, true);
 	maybe_create_new_object(ctx);
-	if (op.extent.offset == 0 && op.extent.length == oi.size)
+	if (op.extent.offset == 0 && op.extent.length >= oi.size)
 	  obs.oi.set_data_digest(osd_op.indata.crc32c(-1));
+	else if (op.extent.offset == oi.size && obs.oi.is_data_digest())
+	  obs.oi.set_data_digest(osd_op.indata.crc32c(obs.oi.data_digest));
 	else
 	  obs.oi.clear_data_digest();
       }