branches/zip: Fix bugs.

buf_LRU_free_block(): Do not allocate the control block when
a compressed-only page is being freed.

buf_validate(): Note that buf_pool->zip_clean may contain blocks
with io_fix == BUF_IO_READ.

buf/buf0buf.c

@@ -2753,7 +2753,20 @@ buf_validate(void)
 	for (b = UT_LIST_GET_FIRST(buf_pool->zip_clean); b;
 	     b = UT_LIST_GET_NEXT(list, b)) {
 		ut_a(buf_page_get_state(b) == BUF_BLOCK_ZIP_PAGE);
-		ut_a(buf_page_get_io_fix(b) == BUF_IO_NONE);
+		switch (buf_page_get_io_fix(b)) {
+		case BUF_IO_NONE:
+			/* All clean blocks should be I/O-unfixed. */
+			break;
+		case BUF_IO_READ:
+			/* In buf_LRU_free_block(), we temporarily set
+			b->io_fix = BUF_IO_READ for a newly allocated
+			control block in order to lock out
+			buf_page_init_for_read(). */
+			break;
+		default:
+			ut_error;
+			break;
+		}
 		ut_a(!b->oldest_modification);
 		ut_a(buf_page_hash_get(b->space, b->offset) == b);
 

buf/buf0lru.c

@@ -919,7 +919,7 @@ buf_LRU_free_block(
 		}
 
 		goto alloc;
-	} else {
+	} else if (buf_page_get_state(bpage) == BUF_BLOCK_FILE_PAGE) {
 		/* Allocate the control block for the compressed page.
 		If it cannot be allocated (without freeing a block
 		from the LRU list), refuse to free bpage. */