Re: [PATCH] iov_iter: Fix build error without CONFIG_CRYPTO

[Sagi Grimberg <sagi@lightbitslabs.com>]

>> If CONFIG_CRYPTO is not set or set to m,
>> gcc building warn this:
>>
>> lib/iov_iter.o: In function `hash_and_copy_to_iter':
>> iov_iter.c:(.text+0x9129): undefined reference to `crypto_stats_get'
>> iov_iter.c:(.text+0x9152): undefined reference to `crypto_stats_ahash_update'
>>
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Fixes: d05f443554b3 ("iov_iter: introduce hash_and_copy_to_iter helper")
>> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> 
> I'm not sure it's the right fix; might be better to have something like
> 
> size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
>                  struct iov_iter *i)
> {
> #ifdef CONFIG_CRYPTO
>          struct ahash_request *hash = hashp;
>          struct scatterlist sg;
>          size_t copied;
> 
>          copied = copy_to_iter(addr, bytes, i);
>          sg_init_one(&sg, addr, copied);
>          ahash_request_set_crypt(hash, &sg, NULL, copied);
>          crypto_ahash_update(hash);
>          return copied;
> #else
> 	return 0;
> #endif
> }
> EXPORT_SYMBOL(hash_and_copy_to_iter);
> 
> instead.  Objections?

Looks better to me.