nvme: map uring_cmd data even if address is 0

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@purestorage.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Xinyu Zhang <xizhang@purestorage.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250227223916.143006-4-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index e0876bc9aacde43f8625c1d015c2bfb7b52a26c0..fe9fb80c6a144f98a369d2eda73d1035fb10905a 100644 (file)
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -513,7 +513,7 @@ 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, issue_flags);