640 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,  in sg_miter_start()  argument
643 	memset(miter, 0, sizeof(struct sg_mapping_iter));  in sg_miter_start()
645 	__sg_page_iter_start(&miter->piter, sgl, nents, 0);  in sg_miter_start()
647 	miter->__flags = flags;  in sg_miter_start()
651 static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)  in sg_miter_get_next_page()  argument
653 	if (!miter->__remaining) {  in sg_miter_get_next_page()
657 		if (!__sg_page_iter_next(&miter->piter))  in sg_miter_get_next_page()
660 		sg = miter->piter.sg;  in sg_miter_get_next_page()
661 		pgoffset = miter->piter.sg_pgoffset;  in sg_miter_get_next_page()
663 		miter->__offset = pgoffset ? 0 : sg->offset;  in sg_miter_get_next_page()
664 		miter->__remaining = sg->offset + sg->length -  in sg_miter_get_next_page()
665 				(pgoffset << PAGE_SHIFT) - miter->__offset;  in sg_miter_get_next_page()
666 		miter->__remaining = min_t(unsigned long, miter->__remaining,  in sg_miter_get_next_page()
667 					   PAGE_SIZE - miter->__offset);  in sg_miter_get_next_page()
691 bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)  in sg_miter_skip()  argument
693 	sg_miter_stop(miter);  in sg_miter_skip()
698 		if (!sg_miter_get_next_page(miter))  in sg_miter_skip()
701 		consumed = min_t(off_t, offset, miter->__remaining);  in sg_miter_skip()
702 		miter->__offset += consumed;  in sg_miter_skip()
703 		miter->__remaining -= consumed;  in sg_miter_skip()
728 bool sg_miter_next(struct sg_mapping_iter *miter)  in sg_miter_next()  argument
730 	sg_miter_stop(miter);  in sg_miter_next()
736 	if (!sg_miter_get_next_page(miter))  in sg_miter_next()
739 	miter->page = sg_page_iter_page(&miter->piter);  in sg_miter_next()
740 	miter->consumed = miter->length = miter->__remaining;  in sg_miter_next()
742 	if (miter->__flags & SG_MITER_ATOMIC)  in sg_miter_next()
743 		miter->addr = kmap_atomic(miter->page) + miter->__offset;  in sg_miter_next()
745 		miter->addr = kmap(miter->page) + miter->__offset;  in sg_miter_next()
765 void sg_miter_stop(struct sg_mapping_iter *miter)  in sg_miter_stop()  argument
767 	WARN_ON(miter->consumed > miter->length);  in sg_miter_stop()
770 	if (miter->addr) {  in sg_miter_stop()
771 		miter->__offset += miter->consumed;  in sg_miter_stop()
772 		miter->__remaining -= miter->consumed;  in sg_miter_stop()
774 		if ((miter->__flags & SG_MITER_TO_SG) &&  in sg_miter_stop()
775 		    !PageSlab(miter->page))  in sg_miter_stop()
776 			flush_kernel_dcache_page(miter->page);  in sg_miter_stop()
778 		if (miter->__flags & SG_MITER_ATOMIC) {  in sg_miter_stop()
780 			kunmap_atomic(miter->addr);  in sg_miter_stop()
782 			kunmap(miter->page);  in sg_miter_stop()
784 		miter->page = NULL;  in sg_miter_stop()
785 		miter->addr = NULL;  in sg_miter_stop()
786 		miter->length = 0;  in sg_miter_stop()
787 		miter->consumed = 0;  in sg_miter_stop()
809 	struct sg_mapping_iter miter;  in sg_copy_buffer()  local
817 	sg_miter_start(&miter, sgl, nents, sg_flags);  in sg_copy_buffer()
819 	if (!sg_miter_skip(&miter, skip))  in sg_copy_buffer()
822 	while ((offset < buflen) && sg_miter_next(&miter)) {  in sg_copy_buffer()
825 		len = min(miter.length, buflen - offset);  in sg_copy_buffer()
828 			memcpy(buf + offset, miter.addr, len);  in sg_copy_buffer()
830 			memcpy(miter.addr, buf + offset, len);  in sg_copy_buffer()
835 	sg_miter_stop(&miter);  in sg_copy_buffer()
924 	struct sg_mapping_iter miter;  in sg_zero_buffer()  local
927 	sg_miter_start(&miter, sgl, nents, sg_flags);  in sg_zero_buffer()
929 	if (!sg_miter_skip(&miter, skip))  in sg_zero_buffer()
932 	while (offset < buflen && sg_miter_next(&miter)) {  in sg_zero_buffer()
935 		len = min(miter.length, buflen - offset);  in sg_zero_buffer()
936 		memset(miter.addr, 0, len);  in sg_zero_buffer()
941 	sg_miter_stop(&miter);  in sg_zero_buffer()