by Justin Stitt

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Subject: Re: [PATCH 7/7] bcachefs: Fix -Wcompare-distinct-pointer-types in bch2_copygc_get_buckets()

On Tue, Sep 12, 2023 at 12:15:44PM -0700, Nathan Chancellor wrote:
> When building bcachefs for 32-bit ARM, there is a warning when using
> max() to compare an expression involving 'size_t' with an 'unsigned
> long' literal:
>
> fs/bcachefs/movinggc.c:159:21: error: comparison of distinct pointer types ('typeof (16UL) *' (aka 'unsigned long *') and 'typeof (buckets_in_flight->nr / 4) *' (aka 'unsigned int *')) [-Werror,-Wcompare-distinct-pointer-types]
> 159 | size_t nr_to_get = max(16UL, buckets_in_flight->nr / 4);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/linux/minmax.h:76:19: note: expanded from macro 'max'
> 76 | #define max(x, y) __careful_cmp(x, y, >)
> | ^~~~~~~~~~~~~~~~~~~~~~
> include/linux/minmax.h:38:24: note: expanded from macro '__careful_cmp'
> 38 | __builtin_choose_expr(__safe_cmp(x, y), \
> | ^~~~~~~~~~~~~~~~
> include/linux/minmax.h:28:4: note: expanded from macro '__safe_cmp'
> 28 | (__typecheck(x, y) && __no_side_effects(x, y))
> | ^~~~~~~~~~~~~~~~~
> include/linux/minmax.h:22:28: note: expanded from macro '__typecheck'
> 22 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
> | ~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~
> 1 error generated.
>
> On 64-bit architectures, size_t is 'unsigned long', so there is no
> warning when comparing these two expressions. Use max_t(size_t, ...) for
> this situation, eliminating the warning.
>
> Fixes: dd49018737d4 ("bcachefs: Rhashtable based buckets_in_flight for copygc")
> Signed-off-by: Nathan Chancellor <[email protected]>
Reviewed-by: Justin Stitt <[email protected]>
> ---
> fs/bcachefs/movinggc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/bcachefs/movinggc.c b/fs/bcachefs/movinggc.c
> index 256431a6dc0c..1cb441d90b34 100644
> --- a/fs/bcachefs/movinggc.c
> +++ b/fs/bcachefs/movinggc.c
> @@ -156,7 +156,7 @@ static int bch2_copygc_get_buckets(struct btree_trans *trans,
> struct bch_fs *c = trans->c;
> struct btree_iter iter;
> struct bkey_s_c k;
> - size_t nr_to_get = max(16UL, buckets_in_flight->nr / 4);
> + size_t nr_to_get = max_t(size_t, 16U, buckets_in_flight->nr / 4);
> size_t saw = 0, in_flight = 0, not_movable = 0, sectors = 0;
> int ret;
>
>
> --
> 2.42.0
>

2023-09-15 08:08:09

by Justin Stitt

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

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 <[email protected]>
Reviewed-by: Justin Stitt <[email protected]>

> ---
> 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
>