f2fs: compress: don't compress any datas after cp stop

While compressed data writeback, we need to drop dirty pages like we did
for non-compressed pages if cp stops, however it's not needed to compress
any data in such case, so let's detect cp stop condition in
cluster_may_compress() to avoid redundant compressing and let following
f2fs_write_raw_pages() drops dirty pages correctly.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/compress.c

@@ -849,6 +849,8 @@ static bool cluster_may_compress(struct compress_ctx *cc)
 		return false;
 	if (!f2fs_cluster_is_full(cc))
 		return false;
+	if (unlikely(f2fs_cp_error(F2FS_I_SB(cc->inode))))
+		return false;
 	return __cluster_may_compress(cc);
 }