[PATCH AUTOSEL 6.1 06/12] btrfs: initialize start_slot in btrfs_log_prealloc_extents

Sasha Levin
2023-10-08T00:50:39Z

From: Josef Bacik <josef@toxicpanda.com>

[ Upstream commit b4c639f699349880b7918b861e1bd360442ec450 ]

Jens reported a compiler warning when using
CONFIG_CC_OPTIMIZE_FOR_SIZE=y that looks like this

fs/btrfs/tree-log.c: In function ‘btrfs_log_prealloc_extents’:
fs/btrfs/tree-log.c:4828:23: warning: ‘start_slot’ may be used
uninitialized [-Wmaybe-uninitialized]
4828 | ret = copy_items(trans, inode, dst_path, path,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4829 | start_slot, ins_nr, 1, 0);
| ~~~~~~~~~~~~~~~~~~~~~~~~~
fs/btrfs/tree-log.c:4725:13: note: ‘start_slot’ was declared here
4725 | int start_slot;
| ^~~~~~~~~~

The compiler is incorrect, as we only use this code when ins_len > 0,
and when ins_len > 0 we have start_slot properly initialized. However
we generally find the -Wmaybe-uninitialized warnings valuable, so
initialize start_slot to get rid of the warning.

Reported-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Josef Bacik <josef@toxicpanda.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/tree-log.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 00be69ce7b90f..451a74a04b99d 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4793,7 +4793,7 @@ static int btrfs_log_prealloc_extents(struct btrfs_trans_handle *trans,
struct extent_buffer *leaf;
int slot;
int ins_nr = 0;
- int start_slot;
+ int start_slot = 0;
int ret;

if (!(inode->flags & BTRFS_INODE_PREALLOC))
--
2.40.1