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* [PATCH v2] nvme: report write pointer for a full zone as zone start + zone len
@ 2021-11-26 10:42 Niklas Cassel
  2021-11-27  1:08 ` Damien Le Moal
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Niklas Cassel @ 2021-11-26 10:42 UTC (permalink / raw)
  To: Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg
  Cc: damien.lemoal, Niklas Cassel, linux-nvme, linux-kernel

From: Niklas Cassel <>

The write pointer in NVMe ZNS is invalid for a zone in zone state full.
The same also holds true for ZAC/ZBC.

The current behavior for NVMe is to simply propagate the wp reported by
the drive, even for full zones. Since the wp is invalid for a full zone,
the wp reported by the drive may be any value.

The way that the sd_zbc driver handles a full zone is to always report
the wp as zone start + zone len, regardless of what the drive reported.
null_blk also follows this convention.

Do the same for NVMe, so that a BLKREPORTZONE ioctl reports the write
pointer for a full zone in a consistent way, regardless of the interface
of the underlying zoned block device.

blkzone report before patch:
start: 0x000040000, len 0x040000, cap 0x03e000, wptr 0xfffffffffffbfff8
reset:0 non-seq:0, zcond:14(fu) [type: 2(SEQ_WRITE_REQUIRED)]

blkzone report after patch:
start: 0x000040000, len 0x040000, cap 0x03e000, wptr 0x040000 reset:0
non-seq:0, zcond:14(fu) [type: 2(SEQ_WRITE_REQUIRED)]

Signed-off-by: Niklas Cassel <>
Changes since v1:
- Minor commit message rewording.
- Use if/else instead of setting wp unconditionally and then
  conditionally updating it.

 drivers/nvme/host/zns.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
index bfc259e0d7b8..9f81beb4df4e 100644
--- a/drivers/nvme/host/zns.c
+++ b/drivers/nvme/host/zns.c
@@ -166,7 +166,10 @@ static int nvme_zone_parse_entry(struct nvme_ns *ns,
 	zone.len = ns->zsze;
 	zone.capacity = nvme_lba_to_sect(ns, le64_to_cpu(entry->zcap));
 	zone.start = nvme_lba_to_sect(ns, le64_to_cpu(entry->zslba));
-	zone.wp = nvme_lba_to_sect(ns, le64_to_cpu(entry->wp));
+	if (zone.cond == BLK_ZONE_COND_FULL)
+		zone.wp = zone.start + zone.len;
+	else
+		zone.wp = nvme_lba_to_sect(ns, le64_to_cpu(entry->wp));
 	return cb(&zone, idx, data);

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2021-12-06  7:54 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-26 10:42 [PATCH v2] nvme: report write pointer for a full zone as zone start + zone len Niklas Cassel
2021-11-27  1:08 ` Damien Le Moal
2021-12-02 13:35 ` Johannes Thumshirn
2021-12-03 16:00 ` Keith Busch
2021-12-06  7:54 ` Christoph Hellwig

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