[PATCH v2] btrfs: make ASSERT no-op in release builds

[Gladyshev Ilya <foxido@foxido.dev>]

The current definition of `ASSERT(cond)` as `(void)(cond)` is redundant,
since these checks have no side effects and don't affect code logic.

However, some checks contain READ_ONCE or other compiler-unfriendly
constructs. For example, ASSERT(list_empty) in btrfs_add_dealloc_inode
was compiled to a redundant mov instruction due to this issue.

This patch defines ASSERT as BUILD_BUG_ON_INVALID for !CONFIG_BTRFS_ASSERT
builds. It also marks `full_page_sectors_uptodate` as __maybe_unused to
suppress "unneeded declaration" warning (it's needed in compile time)

Signed-off-by: Gladyshev Ilya <foxido@foxido.dev>
---
Changes from v1:
- Annotate full_page_sectors_uptodate as __maybe_unused to avoid
  compiler warning

Link to v1: https://lore.kernel.org/linux-btrfs/20251030182322.4085697-1-foxido@foxido.dev/
---
 fs/btrfs/messages.h | 2 +-
 fs/btrfs/raid56.c   | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

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
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 0135dceb7baa..302f20d8c335 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -299,8 +299,8 @@ static int rbio_bucket(struct btrfs_raid_bio *rbio)
 	return hash_64(num >> 16, BTRFS_STRIPE_HASH_TABLE_BITS);
 }
 
-static bool full_page_sectors_uptodate(struct btrfs_raid_bio *rbio,
-				       unsigned int page_nr)
+static __maybe_unused bool full_page_sectors_uptodate(struct btrfs_raid_bio *rbio,
+						      unsigned int page_nr)
 {
 	const u32 sectorsize = rbio->bioc->fs_info->sectorsize;
 	const u32 sectors_per_page = PAGE_SIZE / sectorsize;

base-commit: e53642b87a4f4b03a8d7e5f8507fc3cd0c595ea6
-- 
2.51.1.dirty