[PATCH 5.10.y] nvme: unregister when pr_register() is given a zero new key

[Sasha Levin <sashal@kernel.org>]

From: Daejun Park <daejun7.park@samsung.com>

[ Upstream commit a9d431124fb2e58215daf0299d6fcf47bbc2d6b1 ]

The block layer PR API defines a zero new_key in pr_register() as
unregistering old_key. nvme_pr_register() sends Replace Reservation
Key with a zero NRKEY instead. The host stays registered with key 0,
and its next registration with another key fails with Reservation
Conflict.

The pNFS SCSI layout client unregisters this way at umount. A later
mount cannot register and sends all I/O through the metadata server.

Send Unregister Reservation Key when new_key is zero.

Fixes: 1d277a637a71 ("NVMe: Add persistent reservation ops")
Cc: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Daejun Park <daejun7.park@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
[ sashal: adapted nvme_pr_register() to use the existing old/new parameter names and numeric action codes ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/nvme/host/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 11d7ef36f9670..70784bbf21dc1 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2286,7 +2286,12 @@ static int nvme_pr_register(struct block_device *bdev, u64 old,
 	if (flags & ~PR_FL_IGNORE_KEY)
 		return -EOPNOTSUPP;
 
-	cdw10 = old ? 2 : 0;
+	if (!new)
+		cdw10 = 1;
+	else if (old)
+		cdw10 = 2;
+	else
+		cdw10 = 0;
 	cdw10 |= (flags & PR_FL_IGNORE_KEY) ? 1 << 3 : 0;
 	cdw10 |= (1 << 30) | (1 << 31); /* PTPL=1 */
 	return nvme_pr_command(bdev, cdw10, old, new, nvme_cmd_resv_register);
-- 
2.53.0