/* fetch the pages addr resides in into pg and initialise sg with them */
int __get_userbuf(uint8_t __user *addr, uint32_t len, int write,
unsigned int pgcount, struct page **pg, struct scatterlist *sg,
struct task_struct *task, struct mm_struct *mm)
{
int ret, pglen, i = 0;
struct scatterlist *sgp;
if (unlikely(!pgcount || !len || !addr)) {
sg_mark_end(sg);
return 0;
}
down_read(&mm->mmap_sem);
ret = get_user_pages(task, mm,
(unsigned long)addr, pgcount, write, 0, pg, NULL);
up_read(&mm->mmap_sem);
if (ret != pgcount)
return -EINVAL;
sg_init_table(sg, pgcount);
pglen = min((ptrdiff_t)(PAGE_SIZE - PAGEOFFSET(addr)), (ptrdiff_t)len);
sg_set_page(sg, pg[i++], pglen, PAGEOFFSET(addr));
len -= pglen;
for (sgp = sg_next(sg); len; sgp = sg_next(sgp)) {
pglen = min((uint32_t)PAGE_SIZE, len);
sg_set_page(sgp, pg[i++], pglen, 0);
len -= pglen;
}
sg_mark_end(sg_last(sg, pgcount));
return 0;
}
/*---------------------------------------------------------------------------*/
static struct scatterlist *xio_sg_last(struct sg_table *tbl)
{
#ifdef XIO_DEBUG_SG
verify_tbl(tbl);
#endif
return (!tbl || tbl->nents == 0) ?
NULL : sg_last(tbl->sgl, tbl->nents);
}
