[PATCH v2 2/2] libceph: add KUnit coverage for OSD sparse-read extent validation

[Michael Bommarito <michael.bommarito@gmail.com>]

Add KUnit coverage for the sparse-read extent-map validation added by the
previous patch. The tests drive the real osd_sparse_read() state machine
over a synthesized OSD reply (no OSD or network): an in-range single
extent is accepted and advances the cursor, and an extent whose offset
lies outside the original request range is rejected with -EREMOTEIO before
the message-data cursor is advanced.

The suite is included from osd_client.c so it can exercise the static
sparse-read parser and cursor-advance helpers without exporting test-only
symbols, guarded by CONFIG_CEPH_LIB_KUNIT_TEST.

Assisted-by: Codex:gpt-5-5-xhigh
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
---
 net/ceph/Kconfig            |  12 +++
 net/ceph/osd_client-kunit.c | 146 ++++++++++++++++++++++++++++++++++++
 net/ceph/osd_client.c       |   4 +
 3 files changed, 162 insertions(+)
 create mode 100644 net/ceph/osd_client-kunit.c

diff --git a/net/ceph/Kconfig b/net/ceph/Kconfig
index 7e2528cde4b94..6b78fe4a0f8a4 100644
--- a/net/ceph/Kconfig
+++ b/net/ceph/Kconfig
@@ -45,3 +45,15 @@ config CEPH_LIB_USE_DNS_RESOLVER
 	  Documentation/networking/dns_resolver.rst
 
 	  If unsure, say N.
+
+config CEPH_LIB_KUNIT_TEST
+	bool "KUnit tests for the Ceph core library" if !KUNIT_ALL_TESTS
+	depends on CEPH_LIB && KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds KUnit coverage for selected Ceph core-library parser
+	  and state-machine helpers. The tests exercise internal libceph
+	  behavior with synthesized state and are intended for developer
+	  validation rather than production systems.
+
+	  If unsure, say N.
diff --git a/net/ceph/osd_client-kunit.c b/net/ceph/osd_client-kunit.c
new file mode 100644
index 0000000000000..713f24675f68f
--- /dev/null
+++ b/net/ceph/osd_client-kunit.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit coverage for net/ceph/osd_client.c internals.
+ *
+ * Included from osd_client.c so the test can drive the real static sparse-read
+ * parser and cursor-advance helper without exporting test-only symbols.
+ */
+
+#include <kunit/test.h>
+
+struct ceph_osd_sparse_read_test {
+	struct ceph_osd osd;
+	struct ceph_connection con;
+	struct ceph_msg *msg;
+	struct ceph_msg_data_cursor cursor;
+	struct ceph_osd_request *req;
+	struct page **pages;
+	struct page *page;
+};
+
+static int ceph_osd_sparse_read_test_init(struct kunit *test)
+{
+	struct ceph_osd_sparse_read_test *ctx;
+
+	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, ctx);
+
+	ctx->req = kunit_kzalloc(test, struct_size(ctx->req, r_ops, 1),
+				 GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, ctx->req);
+
+	ctx->pages = kunit_kcalloc(test, 1, sizeof(*ctx->pages), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, ctx->pages);
+
+	ctx->page = alloc_page(GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, ctx->page);
+	ctx->pages[0] = ctx->page;
+
+	ctx->msg = ceph_msg_new2(CEPH_MSG_OSD_OPREPLY, 0, 1, GFP_KERNEL, true);
+	KUNIT_ASSERT_NOT_NULL(test, ctx->msg);
+
+	osd_init(&ctx->osd);
+	ctx->osd.o_sparse_op_idx = -1;
+	ceph_init_sparse_read(&ctx->osd.o_sparse_read);
+
+	request_init(ctx->req);
+	ctx->req->r_tid = 1;
+	ctx->req->r_num_ops = 1;
+	osd_req_op_extent_init(ctx->req, 0, CEPH_OSD_OP_SPARSE_READ,
+			       0, PAGE_SIZE, 0, 0);
+	KUNIT_ASSERT_EQ(test, ctx->req->r_ops[0].op, CEPH_OSD_OP_SPARSE_READ);
+
+	insert_request(&ctx->osd.o_requests, ctx->req);
+
+	ctx->msg->hdr.tid = cpu_to_le64(ctx->req->r_tid);
+	ceph_msg_data_add_pages(ctx->msg, ctx->pages, PAGE_SIZE, 0, false);
+	ceph_msg_data_cursor_init(&ctx->cursor, ctx->msg, PAGE_SIZE);
+
+	ctx->con.private = &ctx->osd;
+	ctx->con.in_msg = ctx->msg;
+
+	test->priv = ctx;
+	return 0;
+}
+
+static void ceph_osd_sparse_read_test_exit(struct kunit *test)
+{
+	struct ceph_osd_sparse_read_test *ctx = test->priv;
+
+	if (!ctx)
+		return;
+
+	if (ctx->req && !RB_EMPTY_NODE(&ctx->req->r_node))
+		erase_request(&ctx->osd.o_requests, ctx->req);
+	ceph_init_sparse_read(&ctx->osd.o_sparse_read);
+	if (ctx->msg)
+		ceph_msg_put(ctx->msg);
+	if (ctx->page)
+		__free_page(ctx->page);
+}
+
+static int ceph_osd_sparse_read_feed_one_extent(struct kunit *test,
+						u64 off, u64 len, u32 datalen)
+{
+	struct ceph_osd_sparse_read_test *ctx = test->priv;
+	struct ceph_sparse_read *sr = &ctx->osd.o_sparse_read;
+	char *buf = NULL;
+	int ret;
+
+	ret = osd_sparse_read(&ctx->con, &ctx->cursor, &buf);
+	KUNIT_ASSERT_EQ(test, ret, (int)sizeof(sr->sr_count));
+	KUNIT_ASSERT_PTR_EQ(test, buf, (char *)&sr->sr_count);
+
+	sr->sr_count = (__force u32)cpu_to_le32(1);
+	ret = osd_sparse_read(&ctx->con, &ctx->cursor, &buf);
+	KUNIT_ASSERT_EQ(test, ret, (int)sizeof(*sr->sr_extent));
+	KUNIT_ASSERT_NOT_NULL(test, sr->sr_extent);
+	KUNIT_ASSERT_PTR_EQ(test, buf, (char *)sr->sr_extent);
+
+	sr->sr_extent[0].off = (__force u64)cpu_to_le64(off);
+	sr->sr_extent[0].len = (__force u64)cpu_to_le64(len);
+	ret = osd_sparse_read(&ctx->con, &ctx->cursor, &buf);
+	KUNIT_ASSERT_EQ(test, ret, (int)sizeof(sr->sr_datalen));
+	KUNIT_ASSERT_PTR_EQ(test, buf, (char *)&sr->sr_datalen);
+
+	sr->sr_datalen = (__force u32)cpu_to_le32(datalen);
+	return osd_sparse_read(&ctx->con, &ctx->cursor, &buf);
+}
+
+static void ceph_osd_sparse_read_in_range_extent(struct kunit *test)
+{
+	struct ceph_osd_sparse_read_test *ctx = test->priv;
+	struct ceph_sparse_read *sr = &ctx->osd.o_sparse_read;
+	int ret;
+
+	ret = ceph_osd_sparse_read_feed_one_extent(test, 0, 16, 16);
+
+	KUNIT_EXPECT_EQ(test, ret, 16);
+	KUNIT_EXPECT_EQ(test, sr->sr_pos, 16);
+	KUNIT_EXPECT_EQ(test, ctx->cursor.sr_resid, 16);
+	KUNIT_EXPECT_EQ(test, ctx->cursor.resid, PAGE_SIZE);
+}
+
+static void ceph_osd_sparse_read_rejects_out_of_range_extent(struct kunit *test)
+{
+	int ret;
+
+	ret = ceph_osd_sparse_read_feed_one_extent(test, PAGE_SIZE + 16, 16, 16);
+
+	KUNIT_EXPECT_EQ(test, ret, -EREMOTEIO);
+}
+
+static struct kunit_case ceph_osd_sparse_read_test_cases[] = {
+	KUNIT_CASE(ceph_osd_sparse_read_in_range_extent),
+	KUNIT_CASE(ceph_osd_sparse_read_rejects_out_of_range_extent),
+	{}
+};
+
+static struct kunit_suite ceph_osd_sparse_read_test_suite = {
+	.name = "ceph_osd_sparse_read",
+	.init = ceph_osd_sparse_read_test_init,
+	.exit = ceph_osd_sparse_read_test_exit,
+	.test_cases = ceph_osd_sparse_read_test_cases,
+};
+
+kunit_test_suite(ceph_osd_sparse_read_test_suite);
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 76ba3abdad9b1..b9ab9608ec88e 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -5951,3 +5951,7 @@ static const struct ceph_connection_operations osd_con_ops = {
 	.handle_auth_done = osd_handle_auth_done,
 	.handle_auth_bad_method = osd_handle_auth_bad_method,
 };
+
+#ifdef CONFIG_CEPH_LIB_KUNIT_TEST
+#include "osd_client-kunit.c"
+#endif
-- 
2.53.0