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From:   Pankaj Raghav <p.raghav@samsung.com>
To:     snitzer@kernel.org, axboe@kernel.dk, agk@redhat.com, hch@lst.de,
        damien.lemoal@opensource.wdc.com
Cc:     jaegeuk@kernel.org, gost.dev@samsung.com, bvanassche@acm.org,
        linux-kernel@vger.kernel.org, hare@suse.de,
        matias.bjorling@wdc.com, Johannes.Thumshirn@wdc.com,
        linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
        pankydev8@gmail.com, dm-devel@redhat.com,
        Pankaj Raghav <p.raghav@samsung.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Chaitanya Kulkarni <kch@nvidia.com>
Subject: [PATCH v15 05/13] nvme: zns: Allow ZNS drives that have
 non-power_of_2 zone size
Date:   Fri, 23 Sep 2022 19:36:10 +0200
Message-Id: <20220923173618.6899-6-p.raghav@samsung.com>
In-Reply-To: <20220923173618.6899-1-p.raghav@samsung.com>
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References: <20220923173618.6899-1-p.raghav@samsung.com>
        <CGME20220923173625eucas1p147864849427469a90bf5c3ce547105c2@eucas1p1.samsung.com>
Precedence: bulk

Remove the condition which disallows non-power_of_2 zone size ZNS drive
to be updated and use generic method to calculate number of zones
instead of relying on log and shift based calculation on zone size.

The power_of_2 calculation has been replaced directly with generic
calculation without special handling. Both modified functions are not
used in hot paths, they are only used during initialization &
revalidation of the ZNS device.

As rounddown macro from math.h does not work for 32 bit architectures,
round down operation is open coded.

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 drivers/nvme/host/zns.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
index 12316ab51bda..fe1d715d61cc 100644
--- a/drivers/nvme/host/zns.c
+++ b/drivers/nvme/host/zns.c
@@ -101,13 +101,6 @@ int nvme_update_zone_info(struct nvme_ns *ns, unsigned lbaf)
 	}
 
 	ns->zsze = nvme_lba_to_sect(ns, le64_to_cpu(id->lbafe[lbaf].zsze));
-	if (!is_power_of_2(ns->zsze)) {
-		dev_warn(ns->ctrl->device,
-			"invalid zone size:%llu for namespace:%u\n",
-			ns->zsze, ns->head->ns_id);
-		status = -ENODEV;
-		goto free_data;
-	}
 
 	disk_set_zoned(ns->disk, BLK_ZONED_HM);
 	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
@@ -129,7 +122,7 @@ static void *nvme_zns_alloc_report_buffer(struct nvme_ns *ns,
 				   sizeof(struct nvme_zone_descriptor);
 
 	nr_zones = min_t(unsigned int, nr_zones,
-			 get_capacity(ns->disk) >> ilog2(ns->zsze));
+			 div64_u64(get_capacity(ns->disk), ns->zsze));
 
 	bufsize = sizeof(struct nvme_zone_report) +
 		nr_zones * sizeof(struct nvme_zone_descriptor);
@@ -182,6 +175,7 @@ int nvme_ns_report_zones(struct nvme_ns *ns, sector_t sector,
 	int ret, zone_idx = 0;
 	unsigned int nz, i;
 	size_t buflen;
+	u64 remainder = 0;
 
 	if (ns->head->ids.csi != NVME_CSI_ZNS)
 		return -EINVAL;
@@ -197,7 +191,9 @@ int nvme_ns_report_zones(struct nvme_ns *ns, sector_t sector,
 	c.zmr.zrasf = NVME_ZRASF_ZONE_REPORT_ALL;
 	c.zmr.pr = NVME_REPORT_ZONE_PARTIAL;
 
-	sector &= ~(ns->zsze - 1);
+	/* Round down the sector value to the nearest zone start */
+	div64_u64_rem(sector, ns->zsze, &remainder);
+	sector -= remainder;
 	while (zone_idx < nr_zones && sector < get_capacity(ns->disk)) {
 		memset(report, 0, buflen);
 
-- 
2.25.1