MDEV-31875 ROW_FORMAT=COMPRESSED table: InnoDB: ... Only 0 bytes read

buf_read_ahead_random(), buf_read_ahead_linear(): Avoid read-ahead
of the last page(s) of ROW_FORMAT=COMPRESSED tablespaces that use
a page size of 1024 or 2048 bytes. We invoke os_file_set_size() on
integer multiples of 4096 bytes in order to be compatible with
the requirements of innodb_flush_method=O_DIRECT regardless of the
physical block size of the underlying storage.

This change must be null-merged to MariaDB Server 10.5 and later.
There, out-of-bounds read-ahead should be handled gracefully
by simply discarding the buffer page that had been allocated.

Tested by: Matthias Leich

storage/innobase/buf/buf0rea.cc

@@ -266,8 +266,24 @@ buf_read_ahead_random(const page_id_t page_id, ulint zip_size, bool ibuf)
 		* buf_read_ahead_random_area;
 
 	if (fil_space_t* space = fil_space_acquire(page_id.space())) {
-		high = space->max_page_number_for_io(high);
+		ulint space_size = space->committed_size;
+		ulint zip_size = space->zip_size();
 		space->release();
+		/* Avoid read-ahead of the last page(s) of
+		small-page-size ROW_FORMAT=COMPRESSED tablespaces,
+		because fil_space_extend_must_retry() would invoke
+		os_file_set_size() on integer multiples of 4 KiB. */
+		switch (UNIV_EXPECT(zip_size, 0)) {
+		case 1024:
+			space_size &= ~ulint{3};
+			break;
+		case 2048:
+			space_size &= ~ulint{1};
+			break;
+		}
+		if (high > space_size) {
+			high = space_size;
+		}
 	} else {
 		return(0);
 	}
@@ -531,7 +547,20 @@ buf_read_ahead_linear(const page_id_t page_id, ulint zip_size, bool ibuf)
 
 	if (fil_space_t* space = fil_space_acquire(page_id.space())) {
 		space_size = space->committed_size;
+		ulint zip_size = space->zip_size();
 		space->release();
+		/* Avoid read-ahead of the last page(s) of
+		small-page-size ROW_FORMAT=COMPRESSED tablespaces,
+		because fil_space_extend_must_retry() would invoke
+		os_file_set_size() on integer multiples of 4 KiB. */
+		switch (UNIV_EXPECT(zip_size, 0)) {
+		case 1024:
+			space_size &= ~ulint{3};
+			break;
+		case 2048:
+			space_size &= ~ulint{1};
+			break;
+		}
 
 		if (high > space_size) {
 			/* The area is not whole */