From 78a8dfbabbece22bee58ac4cb26cab10e7a19c5d Mon Sep 17 00:00:00 2001
From: Romain Izard <romain.izard.pro@gmail.com>
Date: Mon, 29 Jan 2018 11:18:20 +0100
Subject: [PATCH] ubi: Fix error for write access
Git-commit: 78a8dfbabbece22bee58ac4cb26cab10e7a19c5d
Patch-mainline: v4.17-rc1
References: bsc#1051510

When opening a device with write access, ubiblock_open returns an error
code. Currently, this error code is -EPERM, but this is not the right
value.

The open function for other block devices returns -EROFS when opening
read-only devices with FMODE_WRITE set. When used with dm-verity, the
veritysetup userspace tool is expecting EROFS, and refuses to use the
ubiblock device.

Use -EROFS for ubiblock as well. As a result, veritysetup accepts the
ubiblock device as valid.

Cc: stable@vger.kernel.org
Fixes: 9d54c8a33eec (UBI: R/O block driver on top of UBI volumes)
Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/mtd/ubi/block.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -244,7 +244,7 @@ static int ubiblock_open(struct block_de
 	 * in any case.
 	 */
 	if (mode & FMODE_WRITE) {
-		ret = -EPERM;
+		ret = -EROFS;
 		goto out_unlock;
 	}