[PATCH 6/6] tools/testing/selftests: add sample nvme bpf path selector

[hare@kernel.org]

From: Hannes Reinecke <hare@kernel.org>

As a simple nvme bpf path selector to demonstrate the namespace
path iteration.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
---
 .../selftests/bpf/progs/bpf_nvme_simple.c     | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_nvme_simple.c

diff --git a/tools/testing/selftests/bpf/progs/bpf_nvme_simple.c b/tools/testing/selftests/bpf/progs/bpf_nvme_simple.c
new file mode 100644
index 000000000000..c9cafb6bd253
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_nvme_simple.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * simple nvme ebpf path selector
+ *
+ * Simulates a RAID layout with chunk size 2M
+ */
+
+#include <vmlinux.h>
+#include <errno.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+static sector_t simple_offset = 0;
+static sector_t simple_blocksize = 1048576;
+
+SEC("struct_ops")
+int BPF_PROG(simple_select, struct nvme_bpf_iter *iter, sector_t sector)
+{
+	sector_t offset = simple_offset;
+	sector_t block_size = simple_blocksize;
+	u32 num_blks, num_paths, num_iter, i;
+	int cntlid;
+
+	if (sector > offset)
+		sector -= offset;
+	cntlid = nvme_bpf_first_path(iter);
+	if (cntlid < 0)
+		return cntlid;
+	if (!block_size || sector < block_size)
+		return cntlid;
+
+	num_blks = (sector / block_size);
+	num_paths = nvme_bpf_count_paths(iter);
+	num_iter = num_blks % num_paths;
+	bpf_for (i, 1, num_iter) {
+		cntlid = nvme_bpf_next_path(iter);
+		if (cntlid < 0)
+			break;
+	}
+	return cntlid;
+}
+
+SEC(".struct_ops")
+struct nvme_bpf_ops bpf_nvme_simple = {
+	.uuid = { 0x86, 0xee, 0x41, 0xd5, 0x25, 0x6b, 0x45, 0xd0, 0xa4, 0x81, 0x5e, 0x35, 0xf6, 0x02, 0xf5, 0x11 },
+	.subsysnqn = "blktests-subsystem-1",
+	.nsid = 1,
+	.select_path = (void *)simple_select,
+};
-- 
2.43.0