linux-kernel - [PATCH v5 4/4] mtd: add option to enable scanning for partitions

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Date:   Tue, 15 Nov 2022 21:47:25 +0000
From:   Daniel Golle <daniel@...rotopia.org>
To:     Jens Axboe <axboe@...nel.dk>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Golle <daniel@...rotopia.org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Michal Orzel <michalorzel.eng@...il.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org
Subject: [PATCH v5 4/4] mtd: add option to enable scanning for partitions

Add Kconfig boolean CONFIG_MTD_BLOCK_PARTITIONS and enable block
partition parsers on non-NAND mtdblock as well as ubiblock devices
in case it is selected.
Never scan partitions on NAND-backed mtdblock devices, ubiblock
should be used instead.

Signed-off-by: Daniel Golle <daniel@...rotopia.org>
Acked-by: Miquel Raynal <miquel.raynal@...tlin.com>
---
 drivers/mtd/Kconfig       | 11 +++++++++++
 drivers/mtd/mtd_blkdevs.c |  4 +++-
 drivers/mtd/ubi/block.c   |  5 ++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index 796a2eccbef0..12874dec1569 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -69,6 +69,17 @@ config MTD_BLOCK_RO
 	  You do not need this option for use with the DiskOnChip devices. For
 	  those, enable NFTL support (CONFIG_NFTL) instead.
 
+config MTD_BLOCK_PARTITIONS
+	bool "Scan for partitions on MTD block devices"
+	depends on MTD_BLOCK || MTD_BLOCK_RO
+	default y if FIT_PARTITION
+	help
+	  Scan MTD block devices for partitions (ie. MBR, GPT, uImage.FIT, ...).
+	  (NAND devices are omitted, ubiblock should be used instead when)
+
+	  Unless your MTD partitions contain sub-partitions mapped using a
+	  partition table, say no.
+
 comment "Note that in some cases UBI block is preferred. See MTD_UBI_BLOCK."
 	depends on MTD_BLOCK || MTD_BLOCK_RO
 
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 60b222799871..e6f2e0888246 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -359,7 +359,9 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	} else {
 		snprintf(gd->disk_name, sizeof(gd->disk_name),
 			 "%s%d", tr->name, new->devnum);
-		gd->flags |= GENHD_FL_NO_PART;
+
+		if (!IS_ENABLED(CONFIG_MTD_BLOCK_PARTITIONS) || mtd_type_is_nand(new->mtd))
+			gd->flags |= GENHD_FL_NO_PART;
 	}
 
 	set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 75eaecc8639f..e617635ff6e6 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -430,7 +430,10 @@ int ubiblock_create(struct ubi_volume_info *vi)
 		ret = -ENODEV;
 		goto out_cleanup_disk;
 	}
-	gd->flags |= GENHD_FL_NO_PART;
+
+	if (!IS_ENABLED(CONFIG_MTD_BLOCK_PARTITIONS))
+		gd->flags |= GENHD_FL_NO_PART;
+
 	gd->private_data = dev;
 	sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
 	set_capacity(gd, disk_capacity);
-- 
2.38.1