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Bluetooth: hci_uart: Use generic functionality from Broadcom module
[linux/fpc-iii.git] / drivers / block / xen-blkback / blkback.c
blob2a04d341e59888e39da1b20a9f4e6d6f5f1c6c95
1 /******************************************************************************
2 *
3 * Back-end of the driver for virtual block devices. This portion of the
4 * driver exports a 'unified' block-device interface that can be accessed
5 * by any operating system that implements a compatible front end. A
6 * reference front-end implementation can be found in:
7 * drivers/block/xen-blkfront.c
8 *
9 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
10 * Copyright (c) 2005, Christopher Clark
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License version 2
14 * as published by the Free Software Foundation; or, when distributed
15 * separately from the Linux kernel or incorporated into other
16 * software packages, subject to the following license:
17 *
18 * Permission is hereby granted, free of charge, to any person obtaining a copy
19 * of this source file (the "Software"), to deal in the Software without
20 * restriction, including without limitation the rights to use, copy, modify,
21 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
22 * and to permit persons to whom the Software is furnished to do so, subject to
23 * the following conditions:
24 *
25 * The above copyright notice and this permission notice shall be included in
26 * all copies or substantial portions of the Software.
27 *
28 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
29 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
30 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
31 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
32 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
33 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
34 * IN THE SOFTWARE.
35 */
36
37 #include <linux/spinlock.h>
38 #include <linux/kthread.h>
39 #include <linux/list.h>
40 #include <linux/delay.h>
41 #include <linux/freezer.h>
42 #include <linux/bitmap.h>
43
44 #include <xen/events.h>
45 #include <xen/page.h>
46 #include <xen/xen.h>
47 #include <asm/xen/hypervisor.h>
48 #include <asm/xen/hypercall.h>
49 #include <xen/balloon.h>
50 #include <xen/grant_table.h>
51 #include "common.h"
52
53 /*
54 * Maximum number of unused free pages to keep in the internal buffer.
55 * Setting this to a value too low will reduce memory used in each backend,
56 * but can have a performance penalty.
57 *
58 * A sane value is xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST, but can
59 * be set to a lower value that might degrade performance on some intensive
60 * IO workloads.
61 */
62
63 static int xen_blkif_max_buffer_pages = 1024;
64 module_param_named(max_buffer_pages, xen_blkif_max_buffer_pages, int, 0644);
65 MODULE_PARM_DESC(max_buffer_pages,
66 "Maximum number of free pages to keep in each block backend buffer");
67
68 /*
69 * Maximum number of grants to map persistently in blkback. For maximum
70 * performance this should be the total numbers of grants that can be used
71 * to fill the ring, but since this might become too high, specially with
72 * the use of indirect descriptors, we set it to a value that provides good
73 * performance without using too much memory.
74 *
75 * When the list of persistent grants is full we clean it up using a LRU
76 * algorithm.
77 */
78
79 static int xen_blkif_max_pgrants = 1056;
80 module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644);
81 MODULE_PARM_DESC(max_persistent_grants,
82 "Maximum number of grants to map persistently");
83
84 /*
85 * The LRU mechanism to clean the lists of persistent grants needs to
86 * be executed periodically. The time interval between consecutive executions
87 * of the purge mechanism is set in ms.
88 */
89 #define LRU_INTERVAL 100
90
91 /*
92 * When the persistent grants list is full we will remove unused grants
93 * from the list. The percent number of grants to be removed at each LRU
94 * execution.
95 */
96 #define LRU_PERCENT_CLEAN 5
97
98 /* Run-time switchable: /sys/module/blkback/parameters/ */
99 static unsigned int log_stats;
100 module_param(log_stats, int, 0644);
101
102 #define BLKBACK_INVALID_HANDLE (~0)
103
104 /* Number of free pages to remove on each call to gnttab_free_pages */
105 #define NUM_BATCH_FREE_PAGES 10
106
107 static inline int get_free_page(struct xen_blkif *blkif, struct page **page)
108 {
109 unsigned long flags;
110
111 spin_lock_irqsave(&blkif->free_pages_lock, flags);
112 if (list_empty(&blkif->free_pages)) {
113 BUG_ON(blkif->free_pages_num != 0);
114 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
115 return gnttab_alloc_pages(1, page);
116 }
117 BUG_ON(blkif->free_pages_num == 0);
118 page[0] = list_first_entry(&blkif->free_pages, struct page, lru);
119 list_del(&page[0]->lru);
120 blkif->free_pages_num--;
121 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
122
123 return 0;
124 }
125
126 static inline void put_free_pages(struct xen_blkif *blkif, struct page **page,
127 int num)
128 {
129 unsigned long flags;
130 int i;
131
132 spin_lock_irqsave(&blkif->free_pages_lock, flags);
133 for (i = 0; i < num; i++)
134 list_add(&page[i]->lru, &blkif->free_pages);
135 blkif->free_pages_num += num;
136 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
137 }
138
139 static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num)
140 {
141 /* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */
142 struct page *page[NUM_BATCH_FREE_PAGES];
143 unsigned int num_pages = 0;
144 unsigned long flags;
145
146 spin_lock_irqsave(&blkif->free_pages_lock, flags);
147 while (blkif->free_pages_num > num) {
148 BUG_ON(list_empty(&blkif->free_pages));
149 page[num_pages] = list_first_entry(&blkif->free_pages,
150 struct page, lru);
151 list_del(&page[num_pages]->lru);
152 blkif->free_pages_num--;
153 if (++num_pages == NUM_BATCH_FREE_PAGES) {
154 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
155 gnttab_free_pages(num_pages, page);
156 spin_lock_irqsave(&blkif->free_pages_lock, flags);
157 num_pages = 0;
158 }
159 }
160 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
161 if (num_pages != 0)
162 gnttab_free_pages(num_pages, page);
163 }
164
165 #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page)))
166
167 static int do_block_io_op(struct xen_blkif *blkif);
168 static int dispatch_rw_block_io(struct xen_blkif *blkif,
169 struct blkif_request *req,
170 struct pending_req *pending_req);
171 static void make_response(struct xen_blkif *blkif, u64 id,
172 unsigned short op, int st);
173
174 #define foreach_grant_safe(pos, n, rbtree, node) \
175 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \
176 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \
177 &(pos)->node != NULL; \
178 (pos) = container_of(n, typeof(*(pos)), node), \
179 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL)
180
181
182 /*
183 * We don't need locking around the persistent grant helpers
184 * because blkback uses a single-thread for each backed, so we
185 * can be sure that this functions will never be called recursively.
186 *
187 * The only exception to that is put_persistent_grant, that can be called
188 * from interrupt context (by xen_blkbk_unmap), so we have to use atomic
189 * bit operations to modify the flags of a persistent grant and to count
190 * the number of used grants.
191 */
192 static int add_persistent_gnt(struct xen_blkif *blkif,
193 struct persistent_gnt *persistent_gnt)
194 {
195 struct rb_node **new = NULL, *parent = NULL;
196 struct persistent_gnt *this;
197
198 if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) {
199 if (!blkif->vbd.overflow_max_grants)
200 blkif->vbd.overflow_max_grants = 1;
201 return -EBUSY;
202 }
203 /* Figure out where to put new node */
204 new = &blkif->persistent_gnts.rb_node;
205 while (*new) {
206 this = container_of(*new, struct persistent_gnt, node);
207
208 parent = *new;
209 if (persistent_gnt->gnt < this->gnt)
210 new = &((*new)->rb_left);
211 else if (persistent_gnt->gnt > this->gnt)
212 new = &((*new)->rb_right);
213 else {
214 pr_alert_ratelimited(DRV_PFX " trying to add a gref that's already in the tree\n");
215 return -EINVAL;
216 }
217 }
218
219 bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE);
220 set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
221 /* Add new node and rebalance tree. */
222 rb_link_node(&(persistent_gnt->node), parent, new);
223 rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts);
224 blkif->persistent_gnt_c++;
225 atomic_inc(&blkif->persistent_gnt_in_use);
226 return 0;
227 }
228
229 static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif,
230 grant_ref_t gref)
231 {
232 struct persistent_gnt *data;
233 struct rb_node *node = NULL;
234
235 node = blkif->persistent_gnts.rb_node;
236 while (node) {
237 data = container_of(node, struct persistent_gnt, node);
238
239 if (gref < data->gnt)
240 node = node->rb_left;
241 else if (gref > data->gnt)
242 node = node->rb_right;
243 else {
244 if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) {
245 pr_alert_ratelimited(DRV_PFX " requesting a grant already in use\n");
246 return NULL;
247 }
248 set_bit(PERSISTENT_GNT_ACTIVE, data->flags);
249 atomic_inc(&blkif->persistent_gnt_in_use);
250 return data;
251 }
252 }
253 return NULL;
254 }
255
256 static void put_persistent_gnt(struct xen_blkif *blkif,
257 struct persistent_gnt *persistent_gnt)
258 {
259 if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
260 pr_alert_ratelimited(DRV_PFX " freeing a grant already unused");
261 set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
262 clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
263 atomic_dec(&blkif->persistent_gnt_in_use);
264 }
265
266 static void free_persistent_gnts_unmap_callback(int result,
267 struct gntab_unmap_queue_data *data)
268 {
269 struct completion *c = data->data;
270
271 /* BUG_ON used to reproduce existing behaviour,
272 but is this the best way to deal with this? */
273 BUG_ON(result);
274 complete(c);
275 }
276
277 static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
278 unsigned int num)
279 {
280 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
281 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
282 struct persistent_gnt *persistent_gnt;
283 struct rb_node *n;
284 int segs_to_unmap = 0;
285 struct gntab_unmap_queue_data unmap_data;
286 struct completion unmap_completion;
287
288 init_completion(&unmap_completion);
289
290 unmap_data.data = &unmap_completion;
291 unmap_data.done = &free_persistent_gnts_unmap_callback;
292 unmap_data.pages = pages;
293 unmap_data.unmap_ops = unmap;
294 unmap_data.kunmap_ops = NULL;
295
296 foreach_grant_safe(persistent_gnt, n, root, node) {
297 BUG_ON(persistent_gnt->handle ==
298 BLKBACK_INVALID_HANDLE);
299 gnttab_set_unmap_op(&unmap[segs_to_unmap],
300 (unsigned long) pfn_to_kaddr(page_to_pfn(
301 persistent_gnt->page)),
302 GNTMAP_host_map,
303 persistent_gnt->handle);
304
305 pages[segs_to_unmap] = persistent_gnt->page;
306
307 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
308 !rb_next(&persistent_gnt->node)) {
309
310 unmap_data.count = segs_to_unmap;
311 gnttab_unmap_refs_async(&unmap_data);
312 wait_for_completion(&unmap_completion);
313
314 put_free_pages(blkif, pages, segs_to_unmap);
315 segs_to_unmap = 0;
316 }
317
318 rb_erase(&persistent_gnt->node, root);
319 kfree(persistent_gnt);
320 num--;
321 }
322 BUG_ON(num != 0);
323 }
324
325 void xen_blkbk_unmap_purged_grants(struct work_struct *work)
326 {
327 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
328 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
329 struct persistent_gnt *persistent_gnt;
330 int ret, segs_to_unmap = 0;
331 struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work);
332
333 while(!list_empty(&blkif->persistent_purge_list)) {
334 persistent_gnt = list_first_entry(&blkif->persistent_purge_list,
335 struct persistent_gnt,
336 remove_node);
337 list_del(&persistent_gnt->remove_node);
338
339 gnttab_set_unmap_op(&unmap[segs_to_unmap],
340 vaddr(persistent_gnt->page),
341 GNTMAP_host_map,
342 persistent_gnt->handle);
343
344 pages[segs_to_unmap] = persistent_gnt->page;
345
346 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
347 ret = gnttab_unmap_refs(unmap, NULL, pages,
348 segs_to_unmap);
349 BUG_ON(ret);
350 put_free_pages(blkif, pages, segs_to_unmap);
351 segs_to_unmap = 0;
352 }
353 kfree(persistent_gnt);
354 }
355 if (segs_to_unmap > 0) {
356 ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap);
357 BUG_ON(ret);
358 put_free_pages(blkif, pages, segs_to_unmap);
359 }
360 }
361
362 static void purge_persistent_gnt(struct xen_blkif *blkif)
363 {
364 struct persistent_gnt *persistent_gnt;
365 struct rb_node *n;
366 unsigned int num_clean, total;
367 bool scan_used = false, clean_used = false;
368 struct rb_root *root;
369
370 if (blkif->persistent_gnt_c < xen_blkif_max_pgrants ||
371 (blkif->persistent_gnt_c == xen_blkif_max_pgrants &&
372 !blkif->vbd.overflow_max_grants)) {
373 return;
374 }
375
376 if (work_pending(&blkif->persistent_purge_work)) {
377 pr_alert_ratelimited(DRV_PFX "Scheduled work from previous purge is still pending, cannot purge list\n");
378 return;
379 }
380
381 num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
382 num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean;
383 num_clean = min(blkif->persistent_gnt_c, num_clean);
384 if ((num_clean == 0) ||
385 (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use))))
386 return;
387
388 /*
389 * At this point, we can assure that there will be no calls
390 * to get_persistent_grant (because we are executing this code from
391 * xen_blkif_schedule), there can only be calls to put_persistent_gnt,
392 * which means that the number of currently used grants will go down,
393 * but never up, so we will always be able to remove the requested
394 * number of grants.
395 */
396
397 total = num_clean;
398
399 pr_debug(DRV_PFX "Going to purge %u persistent grants\n", num_clean);
400
401 BUG_ON(!list_empty(&blkif->persistent_purge_list));
402 root = &blkif->persistent_gnts;
403 purge_list:
404 foreach_grant_safe(persistent_gnt, n, root, node) {
405 BUG_ON(persistent_gnt->handle ==
406 BLKBACK_INVALID_HANDLE);
407
408 if (clean_used) {
409 clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
410 continue;
411 }
412
413 if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
414 continue;
415 if (!scan_used &&
416 (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags)))
417 continue;
418
419 rb_erase(&persistent_gnt->node, root);
420 list_add(&persistent_gnt->remove_node,
421 &blkif->persistent_purge_list);
422 if (--num_clean == 0)
423 goto finished;
424 }
425 /*
426 * If we get here it means we also need to start cleaning
427 * grants that were used since last purge in order to cope
428 * with the requested num
429 */
430 if (!scan_used && !clean_used) {
431 pr_debug(DRV_PFX "Still missing %u purged frames\n", num_clean);
432 scan_used = true;
433 goto purge_list;
434 }
435 finished:
436 if (!clean_used) {
437 pr_debug(DRV_PFX "Finished scanning for grants to clean, removing used flag\n");
438 clean_used = true;
439 goto purge_list;
440 }
441
442 blkif->persistent_gnt_c -= (total - num_clean);
443 blkif->vbd.overflow_max_grants = 0;
444
445 /* We can defer this work */
446 schedule_work(&blkif->persistent_purge_work);
447 pr_debug(DRV_PFX "Purged %u/%u\n", (total - num_clean), total);
448 return;
449 }
450
451 /*
452 * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
453 */
454 static struct pending_req *alloc_req(struct xen_blkif *blkif)
455 {
456 struct pending_req *req = NULL;
457 unsigned long flags;
458
459 spin_lock_irqsave(&blkif->pending_free_lock, flags);
460 if (!list_empty(&blkif->pending_free)) {
461 req = list_entry(blkif->pending_free.next, struct pending_req,
462 free_list);
463 list_del(&req->free_list);
464 }
465 spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
466 return req;
467 }
468
469 /*
470 * Return the 'pending_req' structure back to the freepool. We also
471 * wake up the thread if it was waiting for a free page.
472 */
473 static void free_req(struct xen_blkif *blkif, struct pending_req *req)
474 {
475 unsigned long flags;
476 int was_empty;
477
478 spin_lock_irqsave(&blkif->pending_free_lock, flags);
479 was_empty = list_empty(&blkif->pending_free);
480 list_add(&req->free_list, &blkif->pending_free);
481 spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
482 if (was_empty)
483 wake_up(&blkif->pending_free_wq);
484 }
485
486 /*
487 * Routines for managing virtual block devices (vbds).
488 */
489 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
490 int operation)
491 {
492 struct xen_vbd *vbd = &blkif->vbd;
493 int rc = -EACCES;
494
495 if ((operation != READ) && vbd->readonly)
496 goto out;
497
498 if (likely(req->nr_sects)) {
499 blkif_sector_t end = req->sector_number + req->nr_sects;
500
501 if (unlikely(end < req->sector_number))
502 goto out;
503 if (unlikely(end > vbd_sz(vbd)))
504 goto out;
505 }
506
507 req->dev = vbd->pdevice;
508 req->bdev = vbd->bdev;
509 rc = 0;
510
511 out:
512 return rc;
513 }
514
515 static void xen_vbd_resize(struct xen_blkif *blkif)
516 {
517 struct xen_vbd *vbd = &blkif->vbd;
518 struct xenbus_transaction xbt;
519 int err;
520 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be);
521 unsigned long long new_size = vbd_sz(vbd);
522
523 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n",
524 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
525 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size);
526 vbd->size = new_size;
527 again:
528 err = xenbus_transaction_start(&xbt);
529 if (err) {
530 pr_warn(DRV_PFX "Error starting transaction");
531 return;
532 }
533 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
534 (unsigned long long)vbd_sz(vbd));
535 if (err) {
536 pr_warn(DRV_PFX "Error writing new size");
537 goto abort;
538 }
539 /*
540 * Write the current state; we will use this to synchronize
541 * the front-end. If the current state is "connected" the
542 * front-end will get the new size information online.
543 */
544 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
545 if (err) {
546 pr_warn(DRV_PFX "Error writing the state");
547 goto abort;
548 }
549
550 err = xenbus_transaction_end(xbt, 0);
551 if (err == -EAGAIN)
552 goto again;
553 if (err)
554 pr_warn(DRV_PFX "Error ending transaction");
555 return;
556 abort:
557 xenbus_transaction_end(xbt, 1);
558 }
559
560 /*
561 * Notification from the guest OS.
562 */
563 static void blkif_notify_work(struct xen_blkif *blkif)
564 {
565 blkif->waiting_reqs = 1;
566 wake_up(&blkif->wq);
567 }
568
569 irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
570 {
571 blkif_notify_work(dev_id);
572 return IRQ_HANDLED;
573 }
574
575 /*
576 * SCHEDULER FUNCTIONS
577 */
578
579 static void print_stats(struct xen_blkif *blkif)
580 {
581 pr_info("xen-blkback (%s): oo %3llu | rd %4llu | wr %4llu | f %4llu"
582 " | ds %4llu | pg: %4u/%4d\n",
583 current->comm, blkif->st_oo_req,
584 blkif->st_rd_req, blkif->st_wr_req,
585 blkif->st_f_req, blkif->st_ds_req,
586 blkif->persistent_gnt_c,
587 xen_blkif_max_pgrants);
588 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
589 blkif->st_rd_req = 0;
590 blkif->st_wr_req = 0;
591 blkif->st_oo_req = 0;
592 blkif->st_ds_req = 0;
593 }
594
595 int xen_blkif_schedule(void *arg)
596 {
597 struct xen_blkif *blkif = arg;
598 struct xen_vbd *vbd = &blkif->vbd;
599 unsigned long timeout;
600 int ret;
601
602 xen_blkif_get(blkif);
603
604 while (!kthread_should_stop()) {
605 if (try_to_freeze())
606 continue;
607 if (unlikely(vbd->size != vbd_sz(vbd)))
608 xen_vbd_resize(blkif);
609
610 timeout = msecs_to_jiffies(LRU_INTERVAL);
611
612 timeout = wait_event_interruptible_timeout(
613 blkif->wq,
614 blkif->waiting_reqs || kthread_should_stop(),
615 timeout);
616 if (timeout == 0)
617 goto purge_gnt_list;
618 timeout = wait_event_interruptible_timeout(
619 blkif->pending_free_wq,
620 !list_empty(&blkif->pending_free) ||
621 kthread_should_stop(),
622 timeout);
623 if (timeout == 0)
624 goto purge_gnt_list;
625
626 blkif->waiting_reqs = 0;
627 smp_mb(); /* clear flag *before* checking for work */
628
629 ret = do_block_io_op(blkif);
630 if (ret > 0)
631 blkif->waiting_reqs = 1;
632 if (ret == -EACCES)
633 wait_event_interruptible(blkif->shutdown_wq,
634 kthread_should_stop());
635
636 purge_gnt_list:
637 if (blkif->vbd.feature_gnt_persistent &&
638 time_after(jiffies, blkif->next_lru)) {
639 purge_persistent_gnt(blkif);
640 blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL);
641 }
642
643 /* Shrink if we have more than xen_blkif_max_buffer_pages */
644 shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages);
645
646 if (log_stats && time_after(jiffies, blkif->st_print))
647 print_stats(blkif);
648 }
649
650 /* Drain pending purge work */
651 flush_work(&blkif->persistent_purge_work);
652
653 if (log_stats)
654 print_stats(blkif);
655
656 blkif->xenblkd = NULL;
657 xen_blkif_put(blkif);
658
659 return 0;
660 }
661
662 /*
663 * Remove persistent grants and empty the pool of free pages
664 */
665 void xen_blkbk_free_caches(struct xen_blkif *blkif)
666 {
667 /* Free all persistent grant pages */
668 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
669 free_persistent_gnts(blkif, &blkif->persistent_gnts,
670 blkif->persistent_gnt_c);
671
672 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
673 blkif->persistent_gnt_c = 0;
674
675 /* Since we are shutting down remove all pages from the buffer */
676 shrink_free_pagepool(blkif, 0 /* All */);
677 }
678
679 static unsigned int xen_blkbk_unmap_prepare(
680 struct xen_blkif *blkif,
681 struct grant_page **pages,
682 unsigned int num,
683 struct gnttab_unmap_grant_ref *unmap_ops,
684 struct page **unmap_pages)
685 {
686 unsigned int i, invcount = 0;
687
688 for (i = 0; i < num; i++) {
689 if (pages[i]->persistent_gnt != NULL) {
690 put_persistent_gnt(blkif, pages[i]->persistent_gnt);
691 continue;
692 }
693 if (pages[i]->handle == BLKBACK_INVALID_HANDLE)
694 continue;
695 unmap_pages[invcount] = pages[i]->page;
696 gnttab_set_unmap_op(&unmap_ops[invcount], vaddr(pages[i]->page),
697 GNTMAP_host_map, pages[i]->handle);
698 pages[i]->handle = BLKBACK_INVALID_HANDLE;
699 invcount++;
700 }
701
702 return invcount;
703 }
704
705 static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_queue_data *data)
706 {
707 struct pending_req* pending_req = (struct pending_req*) (data->data);
708 struct xen_blkif *blkif = pending_req->blkif;
709
710 /* BUG_ON used to reproduce existing behaviour,
711 but is this the best way to deal with this? */
712 BUG_ON(result);
713
714 put_free_pages(blkif, data->pages, data->count);
715 make_response(blkif, pending_req->id,
716 pending_req->operation, pending_req->status);
717 free_req(blkif, pending_req);
718 /*
719 * Make sure the request is freed before releasing blkif,
720 * or there could be a race between free_req and the
721 * cleanup done in xen_blkif_free during shutdown.
722 *
723 * NB: The fact that we might try to wake up pending_free_wq
724 * before drain_complete (in case there's a drain going on)
725 * it's not a problem with our current implementation
726 * because we can assure there's no thread waiting on
727 * pending_free_wq if there's a drain going on, but it has
728 * to be taken into account if the current model is changed.
729 */
730 if (atomic_dec_and_test(&blkif->inflight) && atomic_read(&blkif->drain)) {
731 complete(&blkif->drain_complete);
732 }
733 xen_blkif_put(blkif);
734 }
735
736 static void xen_blkbk_unmap_and_respond(struct pending_req *req)
737 {
738 struct gntab_unmap_queue_data* work = &req->gnttab_unmap_data;
739 struct xen_blkif *blkif = req->blkif;
740 struct grant_page **pages = req->segments;
741 unsigned int invcount;
742
743 invcount = xen_blkbk_unmap_prepare(blkif, pages, req->nr_pages,
744 req->unmap, req->unmap_pages);
745
746 work->data = req;
747 work->done = xen_blkbk_unmap_and_respond_callback;
748 work->unmap_ops = req->unmap;
749 work->kunmap_ops = NULL;
750 work->pages = req->unmap_pages;
751 work->count = invcount;
752
753 gnttab_unmap_refs_async(&req->gnttab_unmap_data);
754 }
755
756
757 /*
758 * Unmap the grant references.
759 *
760 * This could accumulate ops up to the batch size to reduce the number
761 * of hypercalls, but since this is only used in error paths there's
762 * no real need.
763 */
764 static void xen_blkbk_unmap(struct xen_blkif *blkif,
765 struct grant_page *pages[],
766 int num)
767 {
768 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
769 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
770 unsigned int invcount = 0;
771 int ret;
772
773 while (num) {
774 unsigned int batch = min(num, BLKIF_MAX_SEGMENTS_PER_REQUEST);
775
776 invcount = xen_blkbk_unmap_prepare(blkif, pages, batch,
777 unmap, unmap_pages);
778 if (invcount) {
779 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
780 BUG_ON(ret);
781 put_free_pages(blkif, unmap_pages, invcount);
782 }
783 pages += batch;
784 num -= batch;
785 }
786 }
787
788 static int xen_blkbk_map(struct xen_blkif *blkif,
789 struct grant_page *pages[],
790 int num, bool ro)
791 {
792 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
793 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
794 struct persistent_gnt *persistent_gnt = NULL;
795 phys_addr_t addr = 0;
796 int i, seg_idx, new_map_idx;
797 int segs_to_map = 0;
798 int ret = 0;
799 int last_map = 0, map_until = 0;
800 int use_persistent_gnts;
801
802 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
803
804 /*
805 * Fill out preq.nr_sects with proper amount of sectors, and setup
806 * assign map[..] with the PFN of the page in our domain with the
807 * corresponding grant reference for each page.
808 */
809 again:
810 for (i = map_until; i < num; i++) {
811 uint32_t flags;
812
813 if (use_persistent_gnts)
814 persistent_gnt = get_persistent_gnt(
815 blkif,
816 pages[i]->gref);
817
818 if (persistent_gnt) {
819 /*
820 * We are using persistent grants and
821 * the grant is already mapped
822 */
823 pages[i]->page = persistent_gnt->page;
824 pages[i]->persistent_gnt = persistent_gnt;
825 } else {
826 if (get_free_page(blkif, &pages[i]->page))
827 goto out_of_memory;
828 addr = vaddr(pages[i]->page);
829 pages_to_gnt[segs_to_map] = pages[i]->page;
830 pages[i]->persistent_gnt = NULL;
831 flags = GNTMAP_host_map;
832 if (!use_persistent_gnts && ro)
833 flags |= GNTMAP_readonly;
834 gnttab_set_map_op(&map[segs_to_map++], addr,
835 flags, pages[i]->gref,
836 blkif->domid);
837 }
838 map_until = i + 1;
839 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST)
840 break;
841 }
842
843 if (segs_to_map) {
844 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
845 BUG_ON(ret);
846 }
847
848 /*
849 * Now swizzle the MFN in our domain with the MFN from the other domain
850 * so that when we access vaddr(pending_req,i) it has the contents of
851 * the page from the other domain.
852 */
853 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) {
854 if (!pages[seg_idx]->persistent_gnt) {
855 /* This is a newly mapped grant */
856 BUG_ON(new_map_idx >= segs_to_map);
857 if (unlikely(map[new_map_idx].status != 0)) {
858 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
859 put_free_pages(blkif, &pages[seg_idx]->page, 1);
860 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE;
861 ret |= 1;
862 goto next;
863 }
864 pages[seg_idx]->handle = map[new_map_idx].handle;
865 } else {
866 continue;
867 }
868 if (use_persistent_gnts &&
869 blkif->persistent_gnt_c < xen_blkif_max_pgrants) {
870 /*
871 * We are using persistent grants, the grant is
872 * not mapped but we might have room for it.
873 */
874 persistent_gnt = kmalloc(sizeof(struct persistent_gnt),
875 GFP_KERNEL);
876 if (!persistent_gnt) {
877 /*
878 * If we don't have enough memory to
879 * allocate the persistent_gnt struct
880 * map this grant non-persistenly
881 */
882 goto next;
883 }
884 persistent_gnt->gnt = map[new_map_idx].ref;
885 persistent_gnt->handle = map[new_map_idx].handle;
886 persistent_gnt->page = pages[seg_idx]->page;
887 if (add_persistent_gnt(blkif,
888 persistent_gnt)) {
889 kfree(persistent_gnt);
890 persistent_gnt = NULL;
891 goto next;
892 }
893 pages[seg_idx]->persistent_gnt = persistent_gnt;
894 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
895 persistent_gnt->gnt, blkif->persistent_gnt_c,
896 xen_blkif_max_pgrants);
897 goto next;
898 }
899 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) {
900 blkif->vbd.overflow_max_grants = 1;
901 pr_debug(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n",
902 blkif->domid, blkif->vbd.handle);
903 }
904 /*
905 * We could not map this grant persistently, so use it as
906 * a non-persistent grant.
907 */
908 next:
909 new_map_idx++;
910 }
911 segs_to_map = 0;
912 last_map = map_until;
913 if (map_until != num)
914 goto again;
915
916 return ret;
917
918 out_of_memory:
919 pr_alert(DRV_PFX "%s: out of memory\n", __func__);
920 put_free_pages(blkif, pages_to_gnt, segs_to_map);
921 return -ENOMEM;
922 }
923
924 static int xen_blkbk_map_seg(struct pending_req *pending_req)
925 {
926 int rc;
927
928 rc = xen_blkbk_map(pending_req->blkif, pending_req->segments,
929 pending_req->nr_pages,
930 (pending_req->operation != BLKIF_OP_READ));
931
932 return rc;
933 }
934
935 static int xen_blkbk_parse_indirect(struct blkif_request *req,
936 struct pending_req *pending_req,
937 struct seg_buf seg[],
938 struct phys_req *preq)
939 {
940 struct grant_page **pages = pending_req->indirect_pages;
941 struct xen_blkif *blkif = pending_req->blkif;
942 int indirect_grefs, rc, n, nseg, i;
943 struct blkif_request_segment *segments = NULL;
944
945 nseg = pending_req->nr_pages;
946 indirect_grefs = INDIRECT_PAGES(nseg);
947 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
948
949 for (i = 0; i < indirect_grefs; i++)
950 pages[i]->gref = req->u.indirect.indirect_grefs[i];
951
952 rc = xen_blkbk_map(blkif, pages, indirect_grefs, true);
953 if (rc)
954 goto unmap;
955
956 for (n = 0, i = 0; n < nseg; n++) {
957 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) {
958 /* Map indirect segments */
959 if (segments)
960 kunmap_atomic(segments);
961 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page);
962 }
963 i = n % SEGS_PER_INDIRECT_FRAME;
964 pending_req->segments[n]->gref = segments[i].gref;
965 seg[n].nsec = segments[i].last_sect -
966 segments[i].first_sect + 1;
967 seg[n].offset = (segments[i].first_sect << 9);
968 if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) ||
969 (segments[i].last_sect < segments[i].first_sect)) {
970 rc = -EINVAL;
971 goto unmap;
972 }
973 preq->nr_sects += seg[n].nsec;
974 }
975
976 unmap:
977 if (segments)
978 kunmap_atomic(segments);
979 xen_blkbk_unmap(blkif, pages, indirect_grefs);
980 return rc;
981 }
982
983 static int dispatch_discard_io(struct xen_blkif *blkif,
984 struct blkif_request *req)
985 {
986 int err = 0;
987 int status = BLKIF_RSP_OKAY;
988 struct block_device *bdev = blkif->vbd.bdev;
989 unsigned long secure;
990 struct phys_req preq;
991
992 xen_blkif_get(blkif);
993
994 preq.sector_number = req->u.discard.sector_number;
995 preq.nr_sects = req->u.discard.nr_sectors;
996
997 err = xen_vbd_translate(&preq, blkif, WRITE);
998 if (err) {
999 pr_warn(DRV_PFX "access denied: DISCARD [%llu->%llu] on dev=%04x\n",
1000 preq.sector_number,
1001 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
1002 goto fail_response;
1003 }
1004 blkif->st_ds_req++;
1005
1006 secure = (blkif->vbd.discard_secure &&
1007 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
1008 BLKDEV_DISCARD_SECURE : 0;
1009
1010 err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
1011 req->u.discard.nr_sectors,
1012 GFP_KERNEL, secure);
1013 fail_response:
1014 if (err == -EOPNOTSUPP) {
1015 pr_debug(DRV_PFX "discard op failed, not supported\n");
1016 status = BLKIF_RSP_EOPNOTSUPP;
1017 } else if (err)
1018 status = BLKIF_RSP_ERROR;
1019
1020 make_response(blkif, req->u.discard.id, req->operation, status);
1021 xen_blkif_put(blkif);
1022 return err;
1023 }
1024
1025 static int dispatch_other_io(struct xen_blkif *blkif,
1026 struct blkif_request *req,
1027 struct pending_req *pending_req)
1028 {
1029 free_req(blkif, pending_req);
1030 make_response(blkif, req->u.other.id, req->operation,
1031 BLKIF_RSP_EOPNOTSUPP);
1032 return -EIO;
1033 }
1034
1035 static void xen_blk_drain_io(struct xen_blkif *blkif)
1036 {
1037 atomic_set(&blkif->drain, 1);
1038 do {
1039 if (atomic_read(&blkif->inflight) == 0)
1040 break;
1041 wait_for_completion_interruptible_timeout(
1042 &blkif->drain_complete, HZ);
1043
1044 if (!atomic_read(&blkif->drain))
1045 break;
1046 } while (!kthread_should_stop());
1047 atomic_set(&blkif->drain, 0);
1048 }
1049
1050 /*
1051 * Completion callback on the bio's. Called as bh->b_end_io()
1052 */
1053
1054 static void __end_block_io_op(struct pending_req *pending_req, int error)
1055 {
1056 /* An error fails the entire request. */
1057 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) &&
1058 (error == -EOPNOTSUPP)) {
1059 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n");
1060 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
1061 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
1062 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
1063 (error == -EOPNOTSUPP)) {
1064 pr_debug(DRV_PFX "write barrier op failed, not supported\n");
1065 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
1066 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
1067 } else if (error) {
1068 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation,"
1069 " error=%d\n", error);
1070 pending_req->status = BLKIF_RSP_ERROR;
1071 }
1072
1073 /*
1074 * If all of the bio's have completed it is time to unmap
1075 * the grant references associated with 'request' and provide
1076 * the proper response on the ring.
1077 */
1078 if (atomic_dec_and_test(&pending_req->pendcnt))
1079 xen_blkbk_unmap_and_respond(pending_req);
1080 }
1081
1082 /*
1083 * bio callback.
1084 */
1085 static void end_block_io_op(struct bio *bio, int error)
1086 {
1087 __end_block_io_op(bio->bi_private, error);
1088 bio_put(bio);
1089 }
1090
1091
1092
1093 /*
1094 * Function to copy the from the ring buffer the 'struct blkif_request'
1095 * (which has the sectors we want, number of them, grant references, etc),
1096 * and transmute it to the block API to hand it over to the proper block disk.
1097 */
1098 static int
1099 __do_block_io_op(struct xen_blkif *blkif)
1100 {
1101 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1102 struct blkif_request req;
1103 struct pending_req *pending_req;
1104 RING_IDX rc, rp;
1105 int more_to_do = 0;
1106
1107 rc = blk_rings->common.req_cons;
1108 rp = blk_rings->common.sring->req_prod;
1109 rmb(); /* Ensure we see queued requests up to 'rp'. */
1110
1111 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) {
1112 rc = blk_rings->common.rsp_prod_pvt;
1113 pr_warn(DRV_PFX "Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n",
1114 rp, rc, rp - rc, blkif->vbd.pdevice);
1115 return -EACCES;
1116 }
1117 while (rc != rp) {
1118
1119 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
1120 break;
1121
1122 if (kthread_should_stop()) {
1123 more_to_do = 1;
1124 break;
1125 }
1126
1127 pending_req = alloc_req(blkif);
1128 if (NULL == pending_req) {
1129 blkif->st_oo_req++;
1130 more_to_do = 1;
1131 break;
1132 }
1133
1134 switch (blkif->blk_protocol) {
1135 case BLKIF_PROTOCOL_NATIVE:
1136 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
1137 break;
1138 case BLKIF_PROTOCOL_X86_32:
1139 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
1140 break;
1141 case BLKIF_PROTOCOL_X86_64:
1142 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
1143 break;
1144 default:
1145 BUG();
1146 }
1147 blk_rings->common.req_cons = ++rc; /* before make_response() */
1148
1149 /* Apply all sanity checks to /private copy/ of request. */
1150 barrier();
1151
1152 switch (req.operation) {
1153 case BLKIF_OP_READ:
1154 case BLKIF_OP_WRITE:
1155 case BLKIF_OP_WRITE_BARRIER:
1156 case BLKIF_OP_FLUSH_DISKCACHE:
1157 case BLKIF_OP_INDIRECT:
1158 if (dispatch_rw_block_io(blkif, &req, pending_req))
1159 goto done;
1160 break;
1161 case BLKIF_OP_DISCARD:
1162 free_req(blkif, pending_req);
1163 if (dispatch_discard_io(blkif, &req))
1164 goto done;
1165 break;
1166 default:
1167 if (dispatch_other_io(blkif, &req, pending_req))
1168 goto done;
1169 break;
1170 }
1171
1172 /* Yield point for this unbounded loop. */
1173 cond_resched();
1174 }
1175 done:
1176 return more_to_do;
1177 }
1178
1179 static int
1180 do_block_io_op(struct xen_blkif *blkif)
1181 {
1182 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1183 int more_to_do;
1184
1185 do {
1186 more_to_do = __do_block_io_op(blkif);
1187 if (more_to_do)
1188 break;
1189
1190 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
1191 } while (more_to_do);
1192
1193 return more_to_do;
1194 }
1195 /*
1196 * Transmutation of the 'struct blkif_request' to a proper 'struct bio'
1197 * and call the 'submit_bio' to pass it to the underlying storage.
1198 */
1199 static int dispatch_rw_block_io(struct xen_blkif *blkif,
1200 struct blkif_request *req,
1201 struct pending_req *pending_req)
1202 {
1203 struct phys_req preq;
1204 struct seg_buf *seg = pending_req->seg;
1205 unsigned int nseg;
1206 struct bio *bio = NULL;
1207 struct bio **biolist = pending_req->biolist;
1208 int i, nbio = 0;
1209 int operation;
1210 struct blk_plug plug;
1211 bool drain = false;
1212 struct grant_page **pages = pending_req->segments;
1213 unsigned short req_operation;
1214
1215 req_operation = req->operation == BLKIF_OP_INDIRECT ?
1216 req->u.indirect.indirect_op : req->operation;
1217 if ((req->operation == BLKIF_OP_INDIRECT) &&
1218 (req_operation != BLKIF_OP_READ) &&
1219 (req_operation != BLKIF_OP_WRITE)) {
1220 pr_debug(DRV_PFX "Invalid indirect operation (%u)\n",
1221 req_operation);
1222 goto fail_response;
1223 }
1224
1225 switch (req_operation) {
1226 case BLKIF_OP_READ:
1227 blkif->st_rd_req++;
1228 operation = READ;
1229 break;
1230 case BLKIF_OP_WRITE:
1231 blkif->st_wr_req++;
1232 operation = WRITE_ODIRECT;
1233 break;
1234 case BLKIF_OP_WRITE_BARRIER:
1235 drain = true;
1236 case BLKIF_OP_FLUSH_DISKCACHE:
1237 blkif->st_f_req++;
1238 operation = WRITE_FLUSH;
1239 break;
1240 default:
1241 operation = 0; /* make gcc happy */
1242 goto fail_response;
1243 break;
1244 }
1245
1246 /* Check that the number of segments is sane. */
1247 nseg = req->operation == BLKIF_OP_INDIRECT ?
1248 req->u.indirect.nr_segments : req->u.rw.nr_segments;
1249
1250 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
1251 unlikely((req->operation != BLKIF_OP_INDIRECT) &&
1252 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) ||
1253 unlikely((req->operation == BLKIF_OP_INDIRECT) &&
1254 (nseg > MAX_INDIRECT_SEGMENTS))) {
1255 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
1256 nseg);
1257 /* Haven't submitted any bio's yet. */
1258 goto fail_response;
1259 }
1260
1261 preq.nr_sects = 0;
1262
1263 pending_req->blkif = blkif;
1264 pending_req->id = req->u.rw.id;
1265 pending_req->operation = req_operation;
1266 pending_req->status = BLKIF_RSP_OKAY;
1267 pending_req->nr_pages = nseg;
1268
1269 if (req->operation != BLKIF_OP_INDIRECT) {
1270 preq.dev = req->u.rw.handle;
1271 preq.sector_number = req->u.rw.sector_number;
1272 for (i = 0; i < nseg; i++) {
1273 pages[i]->gref = req->u.rw.seg[i].gref;
1274 seg[i].nsec = req->u.rw.seg[i].last_sect -
1275 req->u.rw.seg[i].first_sect + 1;
1276 seg[i].offset = (req->u.rw.seg[i].first_sect << 9);
1277 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
1278 (req->u.rw.seg[i].last_sect <
1279 req->u.rw.seg[i].first_sect))
1280 goto fail_response;
1281 preq.nr_sects += seg[i].nsec;
1282 }
1283 } else {
1284 preq.dev = req->u.indirect.handle;
1285 preq.sector_number = req->u.indirect.sector_number;
1286 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq))
1287 goto fail_response;
1288 }
1289
1290 if (xen_vbd_translate(&preq, blkif, operation) != 0) {
1291 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n",
1292 operation == READ ? "read" : "write",
1293 preq.sector_number,
1294 preq.sector_number + preq.nr_sects,
1295 blkif->vbd.pdevice);
1296 goto fail_response;
1297 }
1298
1299 /*
1300 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev
1301 * is set there.
1302 */
1303 for (i = 0; i < nseg; i++) {
1304 if (((int)preq.sector_number|(int)seg[i].nsec) &
1305 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
1306 pr_debug(DRV_PFX "Misaligned I/O request from domain %d",
1307 blkif->domid);
1308 goto fail_response;
1309 }
1310 }
1311
1312 /* Wait on all outstanding I/O's and once that has been completed
1313 * issue the WRITE_FLUSH.
1314 */
1315 if (drain)
1316 xen_blk_drain_io(pending_req->blkif);
1317
1318 /*
1319 * If we have failed at this point, we need to undo the M2P override,
1320 * set gnttab_set_unmap_op on all of the grant references and perform
1321 * the hypercall to unmap the grants - that is all done in
1322 * xen_blkbk_unmap.
1323 */
1324 if (xen_blkbk_map_seg(pending_req))
1325 goto fail_flush;
1326
1327 /*
1328 * This corresponding xen_blkif_put is done in __end_block_io_op, or
1329 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
1330 */
1331 xen_blkif_get(blkif);
1332 atomic_inc(&blkif->inflight);
1333
1334 for (i = 0; i < nseg; i++) {
1335 while ((bio == NULL) ||
1336 (bio_add_page(bio,
1337 pages[i]->page,
1338 seg[i].nsec << 9,
1339 seg[i].offset) == 0)) {
1340
1341 int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES);
1342 bio = bio_alloc(GFP_KERNEL, nr_iovecs);
1343 if (unlikely(bio == NULL))
1344 goto fail_put_bio;
1345
1346 biolist[nbio++] = bio;
1347 bio->bi_bdev = preq.bdev;
1348 bio->bi_private = pending_req;
1349 bio->bi_end_io = end_block_io_op;
1350 bio->bi_iter.bi_sector = preq.sector_number;
1351 }
1352
1353 preq.sector_number += seg[i].nsec;
1354 }
1355
1356 /* This will be hit if the operation was a flush or discard. */
1357 if (!bio) {
1358 BUG_ON(operation != WRITE_FLUSH);
1359
1360 bio = bio_alloc(GFP_KERNEL, 0);
1361 if (unlikely(bio == NULL))
1362 goto fail_put_bio;
1363
1364 biolist[nbio++] = bio;
1365 bio->bi_bdev = preq.bdev;
1366 bio->bi_private = pending_req;
1367 bio->bi_end_io = end_block_io_op;
1368 }
1369
1370 atomic_set(&pending_req->pendcnt, nbio);
1371 blk_start_plug(&plug);
1372
1373 for (i = 0; i < nbio; i++)
1374 submit_bio(operation, biolist[i]);
1375
1376 /* Let the I/Os go.. */
1377 blk_finish_plug(&plug);
1378
1379 if (operation == READ)
1380 blkif->st_rd_sect += preq.nr_sects;
1381 else if (operation & WRITE)
1382 blkif->st_wr_sect += preq.nr_sects;
1383
1384 return 0;
1385
1386 fail_flush:
1387 xen_blkbk_unmap(blkif, pending_req->segments,
1388 pending_req->nr_pages);
1389 fail_response:
1390 /* Haven't submitted any bio's yet. */
1391 make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR);
1392 free_req(blkif, pending_req);
1393 msleep(1); /* back off a bit */
1394 return -EIO;
1395
1396 fail_put_bio:
1397 for (i = 0; i < nbio; i++)
1398 bio_put(biolist[i]);
1399 atomic_set(&pending_req->pendcnt, 1);
1400 __end_block_io_op(pending_req, -EINVAL);
1401 msleep(1); /* back off a bit */
1402 return -EIO;
1403 }
1404
1405
1406
1407 /*
1408 * Put a response on the ring on how the operation fared.
1409 */
1410 static void make_response(struct xen_blkif *blkif, u64 id,
1411 unsigned short op, int st)
1412 {
1413 struct blkif_response resp;
1414 unsigned long flags;
1415 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1416 int notify;
1417
1418 resp.id = id;
1419 resp.operation = op;
1420 resp.status = st;
1421
1422 spin_lock_irqsave(&blkif->blk_ring_lock, flags);
1423 /* Place on the response ring for the relevant domain. */
1424 switch (blkif->blk_protocol) {
1425 case BLKIF_PROTOCOL_NATIVE:
1426 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
1427 &resp, sizeof(resp));
1428 break;
1429 case BLKIF_PROTOCOL_X86_32:
1430 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
1431 &resp, sizeof(resp));
1432 break;
1433 case BLKIF_PROTOCOL_X86_64:
1434 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
1435 &resp, sizeof(resp));
1436 break;
1437 default:
1438 BUG();
1439 }
1440 blk_rings->common.rsp_prod_pvt++;
1441 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
1442 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
1443 if (notify)
1444 notify_remote_via_irq(blkif->irq);
1445 }
1446
1447 static int __init xen_blkif_init(void)
1448 {
1449 int rc = 0;
1450
1451 if (!xen_domain())
1452 return -ENODEV;
1453
1454 rc = xen_blkif_interface_init();
1455 if (rc)
1456 goto failed_init;
1457
1458 rc = xen_blkif_xenbus_init();
1459 if (rc)
1460 goto failed_init;
1461
1462 failed_init:
1463 return rc;
1464 }
1465
1466 module_init(xen_blkif_init);
1467
1468 MODULE_LICENSE("Dual BSD/GPL");
1469 MODULE_ALIAS("xen-backend:vbd");
Linux with added FPC-III support