linux-kernel - [PATCH 16/16] dm-zoned: ensure only power of 2 zone sizes are allowed

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Message-Id: <20220427160255.300418-17-p.raghav@samsung.com>
Date:   Wed, 27 Apr 2022 18:02:55 +0200
From:   Pankaj Raghav <p.raghav@...sung.com>
To:     jaegeuk@...nel.org, axboe@...nel.dk, snitzer@...nel.org,
        hch@....de, mcgrof@...nel.org, naohiro.aota@....com,
        sagi@...mberg.me, damien.lemoal@...nsource.wdc.com,
        dsterba@...e.com, johannes.thumshirn@....com
Cc:     linux-kernel@...r.kernel.org, linux-btrfs@...r.kernel.org,
        clm@...com, gost.dev@...sung.com, chao@...nel.org,
        linux-f2fs-devel@...ts.sourceforge.net, josef@...icpanda.com,
        jonathan.derrick@...ux.dev, agk@...hat.com, kbusch@...nel.org,
        kch@...dia.com, linux-nvme@...ts.infradead.org,
        dm-devel@...hat.com, bvanassche@....org, jiangbo.365@...edance.com,
        linux-fsdevel@...r.kernel.org, matias.bjorling@....com,
        linux-block@...r.kernel.org, Pankaj Raghav <p.raghav@...sung.com>
Subject: [PATCH 16/16] 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

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 57daa86c19cf..221e0aa0f1a7 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\n",
+		       dm_device_name(md),
+		       bdevname(bdev, bname));
+		return 1;
+	}
 
 	/*
 	 * Check if something changed. If yes, cleanup the current resources
-- 
2.25.1