[PATCH] btrfs: initialize last_extent_end to fix -Wmaybe-uninitialized warning in extent_fiemap()

[PATCH] btrfs: initialize last_extent_end to fix -Wmaybe-uninitialized warning in extent_fiemap()

[David Sterba]

There's a warning (probably on some older compiler version):

fs/btrfs/fiemap.c: warning: 'last_extent_end' may be used uninitialized in this function [-Wmaybe-uninitialized]:  => 822:19

Initialize the variable to 0 although it's not necessary as it's either
properly set or not used after an error. The called function is in the
same file so this is a false alert but we want to fix all
-Wmaybe-uninitialized reports.

Link: https://lore.kernel.org/all/20240819070639.2558629-1-geert@linux-m68k.org/
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/fiemap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/fiemap.c b/fs/btrfs/fiemap.c
index 8f95f3e44e99..df7f09f3b02e 100644
--- a/fs/btrfs/fiemap.c
+++ b/fs/btrfs/fiemap.c
@@ -637,7 +637,7 @@ static int extent_fiemap(struct btrfs_inode *inode,
 	struct btrfs_path *path;
 	struct fiemap_cache cache = { 0 };
 	struct btrfs_backref_share_check_ctx *backref_ctx;
-	u64 last_extent_end;
+	u64 last_extent_end = 0;
 	u64 prev_extent_end;
 	u64 range_start;
 	u64 range_end;
-- 
2.45.0

Re: [PATCH] btrfs: initialize last_extent_end to fix -Wmaybe-uninitialized warning in extent_fiemap()

[Josef Bacik]

On Wed, Aug 21, 2024 at 01:31:32AM +0200, David Sterba wrote:
> There's a warning (probably on some older compiler version):
> 
> fs/btrfs/fiemap.c: warning: 'last_extent_end' may be used uninitialized in this function [-Wmaybe-uninitialized]:  => 822:19
> 
> Initialize the variable to 0 although it's not necessary as it's either
> properly set or not used after an error. The called function is in the
> same file so this is a false alert but we want to fix all
> -Wmaybe-uninitialized reports.
> 
> Link: https://lore.kernel.org/all/20240819070639.2558629-1-geert@linux-m68k.org/
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: David Sterba <dsterba@suse.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef