Fix #2937 (#2940)

Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>

pageserver/src/page_service.rs

@@ -314,6 +314,7 @@ impl PageServerHandler {
 
             let copy_data_bytes = match msg? {
                 Some(FeMessage::CopyData(bytes)) => bytes,
+                Some(FeMessage::Terminate) => break,
                 Some(m) => {
                     bail!("unexpected message: {m:?} during COPY");
                 }

pgxn/neon/pagestore_smgr.c

@@ -267,7 +267,7 @@ readahead_buffer_resize(int newsize, void *extra)
 				nfree = newsize;
 	PrefetchState *newPState;
 	Size 		newprfs_size = offsetof(PrefetchState, prf_buffer) + (
-		sizeof(PrefetchRequest) * readahead_buffer_size
+		sizeof(PrefetchRequest) * newsize
 	);
 	
 	/* don't try to re-initialize if we haven't initialized yet */