f2fs: use COMPRESS_MAPPING to get compress cache mapping

Just use the defined COMPRESS_MAPPING to get compress cache
mapping instaed of direct accessing name.
Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/compress.c

@@ -1901,7 +1901,7 @@ bool f2fs_load_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
 
 void f2fs_invalidate_compress_pages(struct f2fs_sb_info *sbi, nid_t ino)
 {
-	struct address_space *mapping = sbi->compress_inode->i_mapping;
+	struct address_space *mapping = COMPRESS_MAPPING(sbi);
 	struct folio_batch fbatch;
 	pgoff_t index = 0;
 	pgoff_t end = MAX_BLKADDR(sbi);