linux-kernel - [RFC PATCH 1/5] block: add new flag to add partitions read-only

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Date:   Mon, 25 Apr 2022 15:57:54 +0100
From:   Daniel Golle <daniel@...rotopia.org>
To:     linux-block@...r.kernel.org, linux-efi@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Tom Rini <trini@...sulko.com>, Jens Axboe <axboe@...nel.dk>,
        Davidlohr Bueso <dave@...olabs.net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Masahiro Yamada <masahiroy@...nel.org>
Subject: [RFC PATCH 1/5] block: add new flag to add partitions read-only

Add flag ADDPART_FLAG_READONLY to allow partition parsers marking a
partition to be set read-only.
This is needed for the uImage.FIT partition parser added by a follow-up
commit: we need to be sure the contents of uImage.FIT sub-images
remain unaltered they are validated using a hash within the uImage.FIT
structure which also serves as partition table.

Signed-off-by: Daniel Golle <daniel@...rotopia.org>
---
 block/blk.h             | 1 +
 block/partitions/core.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/block/blk.h b/block/blk.h
index 434017701403fb..c20592fe9bed4b 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -404,6 +404,7 @@ void blk_free_ext_minor(unsigned int minor);
 #define ADDPART_FLAG_NONE	0
 #define ADDPART_FLAG_RAID	1
 #define ADDPART_FLAG_WHOLEDISK	2
+#define ADDPART_FLAG_READONLY	4
 int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
 		sector_t length);
 int bdev_del_partition(struct gendisk *disk, int partno);
diff --git a/block/partitions/core.c b/block/partitions/core.c
index 8a0ec929023bcd..3e70860beb655e 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -399,6 +399,9 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
 			goto out_del;
 	}
 
+	if (flags & ADDPART_FLAG_READONLY)
+		bdev->bd_read_only = true;
+
 	/* everything is up and running, commence */
 	err = xa_insert(&disk->part_tbl, partno, bdev, GFP_KERNEL);
 	if (err)
-- 
2.36.0