Commit 2eec5f00 authored Jan 29, 2019 by Anders Roxell Committed by David Sterba Feb 25, 2019

btrfs: let the assertion expression compile in all configs



A compiler warning (in a patch in development) pointed to a variable
that was used only inside and ASSERT:

  u64 root_objectid = root->root_key.objectid;
  ASSERT(root_objectid == ...);

  fs/btrfs/relocation.c: In function ‘insert_dirty_subv’:
  fs/btrfs/relocation.c:2138:6: warning: unused variable ‘root_objectid’ [-Wunused-variable]
    u64 root_objectid = root->root_key.objectid;
	^~~~~~~~~~~~~

When CONFIG_BRTFS_ASSERT isn't enabled, variable root_objectid isn't used.

Rework the assertion helper by adding a runtime check instead of the
'#ifdef CONFIG_BTRFS_ASSERT #else ...", so the compiler sees the
condition being passed into an inline function after preprocessing.

Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

parent 766ece54

fs/btrfs/ctree.h

+5 −8

Original line number	Diff line number	Diff line
		@@ -3518,21 +3518,18 @@ do { \
		rcu_read_unlock(); \
		} while (0)

		#ifdef CONFIG_BTRFS_ASSERT

		__cold
		static inline void assfail(const char expr, const char file, int line)
		{
		if (IS_ENABLED(CONFIG_BTRFS_ASSERT)) {
		pr_err("assertion failed: %s, file: %s, line: %d\n",
		expr, file, line);
		BUG();
		}
		}

		#define ASSERT(expr) \
		(likely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
		#else
		#define ASSERT(expr) ((void)0)
		#endif

		/*
		* Use that for functions that are conditionally exported for sanity tests but

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