[PATCH AUTOSEL 6.6 045/294] btrfs: avoid linker error in btrfs_find_create_tree_block()

Sasha Levin
2025-05-05T22:58:02Z

From: Mark Harmstone <maharmstone@fb.com>

[ Upstream commit 7ef3cbf17d2734ca66c4ed8573be45f4e461e7ee ]

The inline function btrfs_is_testing() is hardcoded to return 0 if
CONFIG_BTRFS_FS_RUN_SANITY_TESTS is not set. Currently we're relying on
the compiler optimizing out the call to alloc_test_extent_buffer() in
btrfs_find_create_tree_block(), as it's not been defined (it's behind an
#ifdef).

Add a stub version of alloc_test_extent_buffer() to avoid linker errors
on non-standard optimization levels. This problem was seen on GCC 14
with -O0 and is helps to see symbols that would be otherwise optimized
out.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Mark Harmstone <maharmstone@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/extent_io.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index b2ae50dcca0fe..ed08d8e5639f5 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3565,10 +3565,10 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
return eb;
}

-#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
u64 start)
{
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
struct extent_buffer *eb, *exists = NULL;
int ret;

@@ -3604,8 +3604,11 @@ struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
free_eb:
btrfs_release_extent_buffer(eb);
return exists;
-}
+#else
+ /* Stub to avoid linker error when compiled with optimizations turned off. */
+ return NULL;
#endif
+}

static struct extent_buffer *grab_extent_buffer(
struct btrfs_fs_info *fs_info, struct page *page)
--
2.39.5