Re: [PATCH 4/7] bcachefs: Fix -Wformat in bch2_bucket_gens_invalid()

[Justin Stitt <justinstitt@google.com>]

On Tue, Sep 12, 2023 at 12:15:41PM -0700, Nathan Chancellor wrote:
> When building bcachefs for 32-bit ARM, there is a compiler warning in
> bch2_bucket_gens_invalid() due to use of an incorrect format specifier:
>
>   fs/bcachefs/alloc_background.c:530:10: error: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Werror,-Wformat]
>     529 |                 prt_printf(err, "bad val size (%lu != %zu)",
>         |                                                ~~~
>         |                                                %zu
>     530 |                        bkey_val_bytes(k.k), sizeof(struct bch_bucket_gens));
>         |                        ^~~~~~~~~~~~~~~~~~~
>   fs/bcachefs/util.h:223:54: note: expanded from macro 'prt_printf'
>     223 | #define prt_printf(_out, ...)           bch2_prt_printf(_out, __VA_ARGS__)
>         |                                                               ^~~~~~~~~~~
>
> On 64-bit architectures, size_t is 'unsigned long', so there is no
> warning when using %lu but on 32-bit architectures, size_t is 'unsigned
> int'. Use '%zu', the format specifier for 'size_t', to eliminate the
> warning.
>
> Fixes: 4be0d766a7e9 ("bcachefs: bucket_gens btree")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Justin Stitt <justinstitt@google.com>

> ---
>  fs/bcachefs/alloc_background.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
> index 67e73864823c..2b0d155d1ed5 100644
> --- a/fs/bcachefs/alloc_background.c
> +++ b/fs/bcachefs/alloc_background.c
> @@ -526,7 +526,7 @@ int bch2_bucket_gens_invalid(const struct bch_fs *c, struct bkey_s_c k,
>  			     struct printbuf *err)
>  {
>  	if (bkey_val_bytes(k.k) != sizeof(struct bch_bucket_gens)) {
> -		prt_printf(err, "bad val size (%lu != %zu)",
> +		prt_printf(err, "bad val size (%zu != %zu)",
>  		       bkey_val_bytes(k.k), sizeof(struct bch_bucket_gens));
>  		return -BCH_ERR_invalid_bkey;
>  	}
>
> --
> 2.42.0
>