[PATCH AUTOSEL 6.14 295/642] nvme: map uring_cmd data even if address is 0

[Sasha Levin]

From: Xinyu Zhang <xizhang at purestorage.com>

[ Upstream commit 99fde895ff56ac2241e7b7b4566731d72f2fdaa7 ]

When using kernel registered bvec fixed buffers, the "address" is
actually the offset into the bvec rather than userspace address.
Therefore it can be 0.

We can skip checking whether the address is NULL before mapping
uring_cmd data. Bad userspace address will be handled properly later when
the user buffer is imported.

With this patch, we will be able to use the kernel registered bvec fixed
buffers in io_uring NVMe passthru with ublk zero-copy support.

Reviewed-by: Caleb Sander Mateos <csander at purestorage.com>
Reviewed-by: Jens Axboe <axboe at kernel.dk>
Reviewed-by: Ming Lei <ming.lei at redhat.com>
Signed-off-by: Xinyu Zhang <xizhang at purestorage.com>
Signed-off-by: Keith Busch <kbusch at kernel.org>
Link: https://lore.kernel.org/r/20250227223916.143006-4-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe at kernel.dk>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/nvme/host/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index fed6b29098ad3..11509ffd28fb5 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -514,7 +514,7 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 		return PTR_ERR(req);
 	req->timeout = d.timeout_ms ? msecs_to_jiffies(d.timeout_ms) : 0;
 
-	if (d.addr && d.data_len) {
+	if (d.data_len) {
 		ret = nvme_map_user_request(req, d.addr,
 			d.data_len, nvme_to_user_ptr(d.metadata),
 			d.metadata_len, ioucmd, vec);
-- 
2.39.5