On 22.03.19 г. 16:07 ч., Arnd Bergmann wrote:
> clang fails to see that the last 'else if() in btrfs_uuid_tree_add()
> is always true, so 'eb' is always initialized correctly:
>
> fs/btrfs/uuid-tree.c:129:13: error: variable 'eb' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
> } else if (ret < 0) {
> ^~~~~~~
> fs/btrfs/uuid-tree.c:139:22: note: uninitialized use occurs here
> write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
> ^~
> fs/btrfs/uuid-tree.c:129:9: note: remove the 'if' if its condition is always true
> } else if (ret < 0) {
> ^~~~~~~~~~~~~
> fs/btrfs/uuid-tree.c:90:26: note: initialize the variable 'eb' to silence this warning
> struct extent_buffer *eb;
> ^
> = NULL
>
> Change it into a plain 'else' to shut up that warning.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=41197
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Such a patch has already been merged to misc-next:
f22898caa6a5 ("btrfs: Turn an 'else if' into an 'else' in
btrfs_uuid_tree_add")
> ---
> fs/btrfs/uuid-tree.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/uuid-tree.c b/fs/btrfs/uuid-tree.c
> index 3b2ae342e649..c1cc9a5c0024 100644
> --- a/fs/btrfs/uuid-tree.c
> +++ b/fs/btrfs/uuid-tree.c
> @@ -126,7 +126,7 @@ int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
> slot = path->slots[0];
> offset = btrfs_item_ptr_offset(eb, slot);
> offset += btrfs_item_size_nr(eb, slot) - sizeof(subid_le);
> - } else if (ret < 0) {
> + } else {
> btrfs_warn(fs_info,
> "insert uuid item failed %d (0x%016llx, 0x%016llx) type %u!",
> ret, (unsigned long long)key.objectid,
>
