linux-kernel - [PATCH v4 13/13] dm-zoned: ensure only power of 2 zone sizes are allowed

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Message-Id: <20220516165416.171196-14-p.raghav@samsung.com>
Date:   Mon, 16 May 2022 18:54:16 +0200
From:   Pankaj Raghav <p.raghav@...sung.com>
To:     axboe@...nel.dk, damien.lemoal@...nsource.wdc.com,
        pankydev8@...il.com, dsterba@...e.com, hch@....de
Cc:     linux-nvme@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
        linux-btrfs@...r.kernel.org, jiangbo.365@...edance.com,
        linux-block@...r.kernel.org, gost.dev@...sung.com,
        p.raghav@...sung.com, linux-kernel@...r.kernel.org,
        dm-devel@...hat.com, Luis Chamberlain <mcgrof@...nel.org>,
        Hannes Reinecke <hare@...e.de>
Subject: [PATCH v4 13/13] dm-zoned: ensure only power of 2 zone sizes are
 allowed

From: Luis Chamberlain <mcgrof@...nel.org>

Today dm-zoned relies on the assumption that you have a zone size
with a power of 2. Even though the block layer today enforces this
requirement, these devices do exist and so provide a stop-gap measure
to ensure these devices cannot be used by mistake

Reviewed-by: Hannes Reinecke <hare@...e.de>
Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
---
 drivers/md/dm-zone.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/md/dm-zone.c b/drivers/md/dm-zone.c
index 3e7b1fe15..f0c588c02 100644
--- a/drivers/md/dm-zone.c
+++ b/drivers/md/dm-zone.c
@@ -231,6 +231,18 @@ static int dm_revalidate_zones(struct mapped_device *md, struct dm_table *t)
 	struct request_queue *q = md->queue;
 	unsigned int noio_flag;
 	int ret;
+	struct block_device *bdev = md->disk->part0;
+	sector_t zone_sectors;
+	char bname[BDEVNAME_SIZE];
+
+	zone_sectors = bdev_zone_sectors(bdev);
+
+	if (!is_power_of_2(zone_sectors)) {
+		DMWARN("%s: %s only power of two zone size supported",
+		       dm_device_name(md),
+		       bdevname(bdev, bname));
+		return -EINVAL;
+	}
 
 	/*
 	 * Check if something changed. If yes, cleanup the current resources
-- 
2.25.1