[PATCH] f2fs: compress: fix zstd data corruption

[Chao Yu]

During zstd compression, ZSTD_endStream() may return non-zero value
because distination buffer is full, but there is still compressed data
remained in intermediate buffer, it means that zstd algorithm can not
save at last one block space, let's just writeback raw data instead of
compressed one, this can fix data corruption when decompressing
incomplete stored compression data.

Signed-off-by: Daeho Jeong <daehojeong@xxxxxxxxxx>
Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
 fs/f2fs/compress.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index c22cc0d37369..5e4947250262 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -358,6 +358,13 @@ static int zstd_compress_pages(struct compress_ctx *cc)
 		return -EIO;
 	}
 
+	/*
+	 * there is compressed data remained in intermediate buffer due to
+	 * no more space in cbuf.cdata
+	 */
+	if (ret)
+		return -EAGAIN;
+
 	cc->clen = outbuf.pos;
 	return 0;
 }
-- 
2.18.0.rc1