linux-kernel - [PATCH v1] mtd: ubi: block: Fix error for write access

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Message-Id: <20180129101820.1692-1-romain.izard.pro@gmail.com>
Date:   Mon, 29 Jan 2018 11:18:20 +0100
From:   Romain Izard <romain.izard.pro@...il.com>
To:     Artem Bityutskiy <dedekind1@...il.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Romain Izard <romain.izard.pro@...il.com>
Subject: [PATCH v1] mtd: ubi: block: Fix error for write access

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.

Fixes: 9d54c8a33eec (UBI: R/O block driver on top of UBI volumes)
Signed-off-by: Romain Izard <romain.izard.pro@...il.com>
---
 drivers/mtd/ubi/block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index b210fdb31c98..4533423cf2aa 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -242,7 +242,7 @@ static int ubiblock_open(struct block_device *bdev, fmode_t mode)
 	 * in any case.
 	 */
 	if (mode & FMODE_WRITE) {
-		ret = -EPERM;
+		ret = -EROFS;
 		goto out_unlock;
 	}
 
-- 
2.14.1