Re: [PATCH] btrfs: fix Wmaybe-uninitialized warning

[David Sterba]

On Tue, Sep 03, 2019 at 12:30:19PM +0900, Austin Kim wrote:
> gcc throws warning message as below:

What version of gcc reports that? 9.2.1 does not.

> âclone_src_i_sizeâ may be used uninitialized in this function
> [-Wmaybe-uninitialized]
>  #define IS_ALIGNED(x, a)  (((x) & ((typeof(x))(a) - 1)) == 0)
>                        ^
> fs/btrfs/send.c:5088:6: note: âclone_src_i_sizeâ was declared here
>  u64 clone_src_i_size;
>    ^
> The clone_src_i_size is only used as call-by-reference
> in a call to get_inode_info().

The reference is passed to a static function, so the compiler has enough
information to determine if it's unused. By inspection I don't see a
problem with the uninitalized variable: if __get_inode_info succeeds,
there's a valid value, in error case it's not used at all.