dm vdo: add basic logging and support utilities

Add various support utilities for the vdo target and deduplication index,
including logging utilities, string and time management, and index-specific
error codes.

Co-developed-by: J. corwin Coburn <corwin@hurlbutnet.net>
Signed-off-by: J. corwin Coburn <corwin@hurlbutnet.net>
Co-developed-by: Michael Sclafani <dm-devel@lists.linux.dev>
Signed-off-by: Michael Sclafani <dm-devel@lists.linux.dev>
Co-developed-by: Thomas Jaskiewicz <tom@jaskiewicz.us>
Signed-off-by: Thomas Jaskiewicz <tom@jaskiewicz.us>
Co-developed-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/md/dm-vdo/permassert.h b/drivers/md/dm-vdo/permassert.h
new file mode 100644
index 000000000000..ee978bc115ec
--- /dev/null
+++ b/drivers/md/dm-vdo/permassert.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef PERMASSERT_H
+#define PERMASSERT_H
+
+#include <linux/compiler.h>
+
+#include "errors.h"
+
+/* Utilities for asserting that certain conditions are met */
+
+#define STRINGIFY(X) #X
+#define STRINGIFY_VALUE(X) STRINGIFY(X)
+
+/*
+ * A hack to apply the "warn if unused" attribute to an integral expression.
+ *
+ * Since GCC doesn't propagate the warn_unused_result attribute to conditional expressions
+ * incorporating calls to functions with that attribute, this function can be used to wrap such an
+ * expression. With optimization enabled, this function contributes no additional instructions, but
+ * the warn_unused_result attribute still applies to the code calling it.
+ */
+static inline int __must_check uds_must_use(int value)
+{
+	return value;
+}
+
+/* Assert that an expression is true and return an error if it is not. */
+#define ASSERT(expr, ...) uds_must_use(__UDS_ASSERT(expr, __VA_ARGS__))
+
+/* Log a message if the expression is not true. */
+#define ASSERT_LOG_ONLY(expr, ...) __UDS_ASSERT(expr, __VA_ARGS__)
+
+#define __UDS_ASSERT(expr, ...)				      \
+	(likely(expr) ? UDS_SUCCESS			      \
+		      : uds_assertion_failed(STRINGIFY(expr), __FILE__, __LINE__, __VA_ARGS__))
+
+/* Log an assertion failure message. */
+int uds_assertion_failed(const char *expression_string, const char *file_name,
+			 int line_number, const char *format, ...)
+	__printf(4, 5);
+
+#endif /* PERMASSERT_H */