linux-kernel - [PATCH AUTOSEL 5.15 12/12] null_blk: Do not allow runt zone with zone capacity smaller then zone size

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Date: Wed,  5 Jun 2024 08:05:22 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Damien Le Moal <dlemoal@...nel.org>,
	Niklas Cassel <cassel@...nel.org>,
	Bart Van Assche <bvanassche@....org>,
	Jens Axboe <axboe@...nel.dk>,
	Sasha Levin <sashal@...nel.org>,
	martin.petersen@...cle.com,
	hare@...e.de,
	linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 12/12] null_blk: Do not allow runt zone with zone capacity smaller then zone size

From: Damien Le Moal <dlemoal@...nel.org>

[ Upstream commit b164316808ec5de391c3e7b0148ec937d32d280d ]

A zoned device with a smaller last zone together with a zone capacity
smaller than the zone size does make any sense as that does not
correspond to any possible setup for a real device:
1) For ZNS and zoned UFS devices, all zones are always the same size.
2) For SMR HDDs, all zones always have the same capacity.
In other words, if we have a smaller last runt zone, then this zone
capacity should always be equal to the zone size.

Add a check in null_init_zoned_dev() to prevent a configuration to have
both a smaller zone size and a zone capacity smaller than the zone size.

Signed-off-by: Damien Le Moal <dlemoal@...nel.org>
Reviewed-by: Niklas Cassel <cassel@...nel.org>
Reviewed-by: Bart Van Assche <bvanassche@....org>
Link: https://lore.kernel.org/r/20240530054035.491497-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/block/null_blk/zoned.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/block/null_blk/zoned.c b/drivers/block/null_blk/zoned.c
index dae54dd1aeac3..e0819b04d288f 100644
--- a/drivers/block/null_blk/zoned.c
+++ b/drivers/block/null_blk/zoned.c
@@ -80,6 +80,17 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
 		return -EINVAL;
 	}
 
+	/*
+	 * If a smaller zone capacity was requested, do not allow a smaller last
+	 * zone at the same time as such zone configuration does not correspond
+	 * to any real zoned device.
+	 */
+	if (dev->zone_capacity != dev->zone_size &&
+	    dev->size & (dev->zone_size - 1)) {
+		pr_err("A smaller last zone is not allowed with zone capacity smaller than zone size.\n");
+		return -EINVAL;
+	}
+
 	zone_capacity_sects = mb_to_sects(dev->zone_capacity);
 	dev_capacity_sects = mb_to_sects(dev->size);
 	dev->zone_size_sects = mb_to_sects(dev->zone_size);
-- 
2.43.0