ext4: clear BH_Uptodate flag on decryption error

If decryption fails, ext4_block_write_begin() can return with the page's
buffer_head marked with the BH_Uptodate flag.  This commit clears the
BH_Uptodate flag in such cases.
Signed-off-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>

fs/ext4/inode.c

@@ -1229,10 +1229,14 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 		if (!buffer_uptodate(*wait_bh))
 			err = -EIO;
 	}
-	if (unlikely(err))
+	if (unlikely(err)) {
 		page_zero_new_buffers(page, from, to);
-	else if (decrypt)
+	} else if (decrypt) {
 		err = fscrypt_decrypt_pagecache_blocks(page, PAGE_SIZE, 0);
+		if (err)
+			clear_buffer_uptodate(*wait_bh);
+	}
+
 	return err;
 }
 #endif