Christoph,
On 2019/06/27 16:28, Christoph Hellwig wrote:
>> +#ifdef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
>
> That seems like an odd constructu, as you don't call
> flush_kernel_dcache_page. From looking whoe defines it it seems
> to be about the right set of architectures, but that might be
> by a mix of chance and similar requirements for cache flushing.
This comes from include/linux/highmem.h:
#ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
static inline void flush_kernel_dcache_page(struct page *page)
{
}
static inline void flush_kernel_vmap_range(void *vaddr, int size)
{
}
static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
{
}
#endif
which I guessed is for the architectures that do not need the flush/invalidate
vmap functions. I copied. Is there a better way ? The point was to avoid doing
the loop on the bvec for the range length on architectures that have an empty
definition of invalidate_kernel_vmap_range().
>
>> +static void bio_invalidate_vmalloc_pages(struct bio *bio)
>> +{
>> + if (bio->bi_private) {
>> + struct bvec_iter_all iter_all;
>> + struct bio_vec *bvec;
>> + unsigned long len = 0;
>> +
>> + bio_for_each_segment_all(bvec, bio, iter_all)
>> + len += bvec->bv_len;
>> + invalidate_kernel_vmap_range(bio->bi_private, len);
>
> We control the bio here, so we can directly iterate over the
> segments instead of doing the fairly expensive bio_for_each_segment_all
> call that goes to each page and builds a bvec for it.
OK. Got it. Will update it.
>
>> + struct page *page;
>> int offset, i;
>> struct bio *bio;
>>
>> @@ -1508,6 +1529,12 @@ struct bio *bio_map_kern(struct request_queue *q,
>> void *data, unsigned int len,
>> if (!bio)
>> return ERR_PTR(-ENOMEM);
>>
>> + if (is_vmalloc) {
>> + flush_kernel_vmap_range(data, len);
>> + if ((!op_is_write(bio_op(bio))))
>> + bio->bi_private = data;
>> + }
>
> We've just allocate the bio, so bio->bi_opf is not actually set at
> this point unfortunately.
OK. I will move the check to the completion path then.
Thanks !
--
Damien Le Moal
Western Digital Research
