[PATCH] btrfs: make ASSERT no-op in release builds

[Gladyshev Ilya <foxido@foxido.dev>]

The current definition of `ASSERT(cond)` as `(void)(cond)` is redundant,
because all checks are without side effects and don't affect code logic.

However, some checks has READ_ONCE in them or other 'compiler-unfriendly'
behaviour. For example, ASSERT(list_empty) in btrfs_add_dealloc_inode
was compiled to redundant mov because of this.

This patch replaces ASSERT with BUILD_BUG_ON_INVALID for
!CONFIG_BTRFS_ASSERT builds.

Signed-off-by: Gladyshev Ilya <foxido@foxido.dev>

---
.o size reductions are not that big, for example on defconfig + btrfs
fs/btrfs/*.o size went from 3280528 to 3277936, so compiler was pretty
efficient on his own
---
 fs/btrfs/messages.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/messages.h b/fs/btrfs/messages.h
index 4416c165644f..f80fe40a2c2b 100644
--- a/fs/btrfs/messages.h
+++ b/fs/btrfs/messages.h
@@ -168,7 +168,7 @@ do {										\
 #endif
 
 #else
-#define ASSERT(cond, args...)			(void)(cond)
+#define ASSERT(cond, args...)			BUILD_BUG_ON_INVALID(cond)
 #endif
 
 #ifdef CONFIG_BTRFS_DEBUG

base-commit: e53642b87a4f4b03a8d7e5f8507fc3cd0c595ea6
-- 
2.51.1.dirty