Scsi - Index of

195 * pick up from where this one left off. */
196
197 unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
198 unsigned int buflen, struct scsi_cmnd *srb, unsigned int *index,
199 unsigned int *offset, enum xfer_buf_dir dir)
200 {
201 unsigned int cnt;
202
203 /* If not using scatter-gather, just transfer the data directly.
204 * Make certain it will fit in the available buffer space. */
205 if (srb->use_sg == 0) {
206 if (*offset >= srb->request_bufflen)
207 return 0;
208 cnt = min(buflen, srb->request_bufflen - *offset);
209 if (dir == TO_XFER_BUF)
210 memcpy((unsigned char *) srb->request_buffer + *offset,
211 buffer, cnt);
212 else
213 memcpy(buffer, (unsigned char *) srb->request_buffer +
214 *offset, cnt);
215 *offset += cnt;
216
217 /* Using scatter-gather. We have to go through the list one entry
218 * at a time. Each s-g entry contains some number of pages, and
219 * each page has to be kmap()'ed separately. If the page is already
220 * in kernel-addressable memory then kmap() will return its address.
221 * If the page is not directly accessible -- such as a user buffer
222 * located in high memory -- then kmap() will map it to a temporary
223 * position in the kernel's virtual address space. */
224 } else {
225 struct scatterlist *sg =
226 (struct scatterlist *) srb->request_buffer
227 + *index;
228
229 /* This loop handles a single s-g list entry, which may
230 * include multiple pages. Find the initial page structure
133
231 * and the starting offset within the page, and update
232 * the *offset and *index values for the next loop. */
233 cnt = 0;
234 while (cnt < buflen && *index < srb->use_sg) {
235 struct page *page = sg->page +
236 ((sg->offset + *offset) >> PAGE_SHIFT);
237 unsigned int poff =