-#ifdef SG_ALLOW_DIO_CODE
-/* vvvvvvvv following code borrowed from st driver's direct IO vvvvvvvvv */
- /* TODO: hopefully we can use the generic block layer code */
-
-/* Pin down user pages and put them into a scatter gather list. Returns <= 0 if
- - mapping of all pages not successful
- (i.e., either completely successful or fails)
-*/
-static int
-st_map_user_pages(struct scatterlist *sgl, const unsigned int max_pages,
- unsigned long uaddr, size_t count, int rw)
-{
- unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
- unsigned long start = uaddr >> PAGE_SHIFT;
- const int nr_pages = end - start;
- int res, i, j;
- struct page **pages;
-
- /* User attempted Overflow! */
- if ((uaddr + count) < uaddr)
- return -EINVAL;
-
- /* Too big */
- if (nr_pages > max_pages)
- return -ENOMEM;
-
- /* Hmm? */
- if (count == 0)
- return 0;
-
- if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_ATOMIC)) == NULL)
- return -ENOMEM;
-
- /* Try to fault in all of the necessary pages */
- down_read(¤t->mm->mmap_sem);
- /* rw==READ means read from drive, write into memory area */
- res = get_user_pages(
- current,
- current->mm,
- uaddr,
- nr_pages,
- rw == READ,
- 0, /* don't force */
- pages,
- NULL);
- up_read(¤t->mm->mmap_sem);
-
- /* Errors and no page mapped should return here */
- if (res < nr_pages)
- goto out_unmap;
-
- for (i=0; i < nr_pages; i++) {
- /* FIXME: flush superflous for rw==READ,
- * probably wrong function for rw==WRITE
- */
- flush_dcache_page(pages[i]);
- /* ?? Is locking needed? I don't think so */
- /* if (!trylock_page(pages[i]))
- goto out_unlock; */
- }
-
- sg_set_page(sgl, pages[0], 0, uaddr & ~PAGE_MASK);
- if (nr_pages > 1) {
- sgl[0].length = PAGE_SIZE - sgl[0].offset;
- count -= sgl[0].length;
- for (i=1; i < nr_pages ; i++)
- sg_set_page(&sgl[i], pages[i], count < PAGE_SIZE ? count : PAGE_SIZE, 0);
- }
- else {
- sgl[0].length = count;
- }
-
- kfree(pages);
- return nr_pages;
-
- out_unmap:
- if (res > 0) {
- for (j=0; j < res; j++)
- page_cache_release(pages[j]);
- res = 0;
- }
- kfree(pages);
- return res;
-}
-
-
-/* And unmap them... */
-static int
-st_unmap_user_pages(struct scatterlist *sgl, const unsigned int nr_pages,
- int dirtied)
-{
- int i;
-
- for (i=0; i < nr_pages; i++) {
- struct page *page = sg_page(&sgl[i]);
-
- if (dirtied)
- SetPageDirty(page);
- /* unlock_page(page); */
- /* FIXME: cache flush missing for rw==READ
- * FIXME: call the correct reference counting function
- */
- page_cache_release(page);
- }
-
- return 0;
-}
-
-/* ^^^^^^^^ above code borrowed from st driver's direct IO ^^^^^^^^^ */
-#endif
-
-
-/* Returns: -ve -> error, 0 -> done, 1 -> try indirect */
-static int
-sg_build_direct(Sg_request * srp, Sg_fd * sfp, int dxfer_len)
-{
-#ifdef SG_ALLOW_DIO_CODE
- sg_io_hdr_t *hp = &srp->header;
- Sg_scatter_hold *schp = &srp->data;
- int sg_tablesize = sfp->parentdp->sg_tablesize;
- int mx_sc_elems, res;
- struct scsi_device *sdev = sfp->parentdp->device;
-
- if (((unsigned long)hp->dxferp &
- queue_dma_alignment(sdev->request_queue)) != 0)
- return 1;
-
- mx_sc_elems = sg_build_sgat(schp, sfp, sg_tablesize);
- if (mx_sc_elems <= 0) {
- return 1;
- }
- res = st_map_user_pages(schp->buffer, mx_sc_elems,
- (unsigned long)hp->dxferp, dxfer_len,
- (SG_DXFER_TO_DEV == hp->dxfer_direction) ? 1 : 0);
- if (res <= 0) {
- sg_remove_scat(schp);
- return 1;
- }
- schp->k_use_sg = res;
- schp->dio_in_use = 1;
- hp->info |= SG_INFO_DIRECT_IO;
- return 0;
-#else
- return 1;
-#endif
-}
-