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Linux 3.11-rc3
[cris-mirror.git] / drivers / block / xen-blkback / blkback.c
blobbf4b9d282c042ec4d5b3c31a9d3192bd059afcc5
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 "common.h"
51
52 /*
53 * Maximum number of unused free pages to keep in the internal buffer.
54 * Setting this to a value too low will reduce memory used in each backend,
55 * but can have a performance penalty.
56 *
57 * A sane value is xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST, but can
58 * be set to a lower value that might degrade performance on some intensive
59 * IO workloads.
60 */
61
62 static int xen_blkif_max_buffer_pages = 1024;
63 module_param_named(max_buffer_pages, xen_blkif_max_buffer_pages, int, 0644);
64 MODULE_PARM_DESC(max_buffer_pages,
65 "Maximum number of free pages to keep in each block backend buffer");
66
67 /*
68 * Maximum number of grants to map persistently in blkback. For maximum
69 * performance this should be the total numbers of grants that can be used
70 * to fill the ring, but since this might become too high, specially with
71 * the use of indirect descriptors, we set it to a value that provides good
72 * performance without using too much memory.
73 *
74 * When the list of persistent grants is full we clean it up using a LRU
75 * algorithm.
76 */
77
78 static int xen_blkif_max_pgrants = 1056;
79 module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644);
80 MODULE_PARM_DESC(max_persistent_grants,
81 "Maximum number of grants to map persistently");
82
83 /*
84 * The LRU mechanism to clean the lists of persistent grants needs to
85 * be executed periodically. The time interval between consecutive executions
86 * of the purge mechanism is set in ms.
87 */
88 #define LRU_INTERVAL 100
89
90 /*
91 * When the persistent grants list is full we will remove unused grants
92 * from the list. The percent number of grants to be removed at each LRU
93 * execution.
94 */
95 #define LRU_PERCENT_CLEAN 5
96
97 /* Run-time switchable: /sys/module/blkback/parameters/ */
98 static unsigned int log_stats;
99 module_param(log_stats, int, 0644);
100
101 #define BLKBACK_INVALID_HANDLE (~0)
102
103 /* Number of free pages to remove on each call to free_xenballooned_pages */
104 #define NUM_BATCH_FREE_PAGES 10
105
106 static inline int get_free_page(struct xen_blkif *blkif, struct page **page)
107 {
108 unsigned long flags;
109
110 spin_lock_irqsave(&blkif->free_pages_lock, flags);
111 if (list_empty(&blkif->free_pages)) {
112 BUG_ON(blkif->free_pages_num != 0);
113 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
114 return alloc_xenballooned_pages(1, page, false);
115 }
116 BUG_ON(blkif->free_pages_num == 0);
117 page[0] = list_first_entry(&blkif->free_pages, struct page, lru);
118 list_del(&page[0]->lru);
119 blkif->free_pages_num--;
120 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
121
122 return 0;
123 }
124
125 static inline void put_free_pages(struct xen_blkif *blkif, struct page **page,
126 int num)
127 {
128 unsigned long flags;
129 int i;
130
131 spin_lock_irqsave(&blkif->free_pages_lock, flags);
132 for (i = 0; i < num; i++)
133 list_add(&page[i]->lru, &blkif->free_pages);
134 blkif->free_pages_num += num;
135 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
136 }
137
138 static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num)
139 {
140 /* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */
141 struct page *page[NUM_BATCH_FREE_PAGES];
142 unsigned int num_pages = 0;
143 unsigned long flags;
144
145 spin_lock_irqsave(&blkif->free_pages_lock, flags);
146 while (blkif->free_pages_num > num) {
147 BUG_ON(list_empty(&blkif->free_pages));
148 page[num_pages] = list_first_entry(&blkif->free_pages,
149 struct page, lru);
150 list_del(&page[num_pages]->lru);
151 blkif->free_pages_num--;
152 if (++num_pages == NUM_BATCH_FREE_PAGES) {
153 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
154 free_xenballooned_pages(num_pages, page);
155 spin_lock_irqsave(&blkif->free_pages_lock, flags);
156 num_pages = 0;
157 }
158 }
159 spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
160 if (num_pages != 0)
161 free_xenballooned_pages(num_pages, page);
162 }
163
164 #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page)))
165
166 static int do_block_io_op(struct xen_blkif *blkif);
167 static int dispatch_rw_block_io(struct xen_blkif *blkif,
168 struct blkif_request *req,
169 struct pending_req *pending_req);
170 static void make_response(struct xen_blkif *blkif, u64 id,
171 unsigned short op, int st);
172
173 #define foreach_grant_safe(pos, n, rbtree, node) \
174 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \
175 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \
176 &(pos)->node != NULL; \
177 (pos) = container_of(n, typeof(*(pos)), node), \
178 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL)
179
180
181 /*
182 * We don't need locking around the persistent grant helpers
183 * because blkback uses a single-thread for each backed, so we
184 * can be sure that this functions will never be called recursively.
185 *
186 * The only exception to that is put_persistent_grant, that can be called
187 * from interrupt context (by xen_blkbk_unmap), so we have to use atomic
188 * bit operations to modify the flags of a persistent grant and to count
189 * the number of used grants.
190 */
191 static int add_persistent_gnt(struct xen_blkif *blkif,
192 struct persistent_gnt *persistent_gnt)
193 {
194 struct rb_node **new = NULL, *parent = NULL;
195 struct persistent_gnt *this;
196
197 if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) {
198 if (!blkif->vbd.overflow_max_grants)
199 blkif->vbd.overflow_max_grants = 1;
200 return -EBUSY;
201 }
202 /* Figure out where to put new node */
203 new = &blkif->persistent_gnts.rb_node;
204 while (*new) {
205 this = container_of(*new, struct persistent_gnt, node);
206
207 parent = *new;
208 if (persistent_gnt->gnt < this->gnt)
209 new = &((*new)->rb_left);
210 else if (persistent_gnt->gnt > this->gnt)
211 new = &((*new)->rb_right);
212 else {
213 pr_alert_ratelimited(DRV_PFX " trying to add a gref that's already in the tree\n");
214 return -EINVAL;
215 }
216 }
217
218 bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE);
219 set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
220 /* Add new node and rebalance tree. */
221 rb_link_node(&(persistent_gnt->node), parent, new);
222 rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts);
223 blkif->persistent_gnt_c++;
224 atomic_inc(&blkif->persistent_gnt_in_use);
225 return 0;
226 }
227
228 static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif,
229 grant_ref_t gref)
230 {
231 struct persistent_gnt *data;
232 struct rb_node *node = NULL;
233
234 node = blkif->persistent_gnts.rb_node;
235 while (node) {
236 data = container_of(node, struct persistent_gnt, node);
237
238 if (gref < data->gnt)
239 node = node->rb_left;
240 else if (gref > data->gnt)
241 node = node->rb_right;
242 else {
243 if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) {
244 pr_alert_ratelimited(DRV_PFX " requesting a grant already in use\n");
245 return NULL;
246 }
247 set_bit(PERSISTENT_GNT_ACTIVE, data->flags);
248 atomic_inc(&blkif->persistent_gnt_in_use);
249 return data;
250 }
251 }
252 return NULL;
253 }
254
255 static void put_persistent_gnt(struct xen_blkif *blkif,
256 struct persistent_gnt *persistent_gnt)
257 {
258 if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
259 pr_alert_ratelimited(DRV_PFX " freeing a grant already unused");
260 set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
261 clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
262 atomic_dec(&blkif->persistent_gnt_in_use);
263 }
264
265 static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
266 unsigned int num)
267 {
268 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
269 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
270 struct persistent_gnt *persistent_gnt;
271 struct rb_node *n;
272 int ret = 0;
273 int segs_to_unmap = 0;
274
275 foreach_grant_safe(persistent_gnt, n, root, node) {
276 BUG_ON(persistent_gnt->handle ==
277 BLKBACK_INVALID_HANDLE);
278 gnttab_set_unmap_op(&unmap[segs_to_unmap],
279 (unsigned long) pfn_to_kaddr(page_to_pfn(
280 persistent_gnt->page)),
281 GNTMAP_host_map,
282 persistent_gnt->handle);
283
284 pages[segs_to_unmap] = persistent_gnt->page;
285
286 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
287 !rb_next(&persistent_gnt->node)) {
288 ret = gnttab_unmap_refs(unmap, NULL, pages,
289 segs_to_unmap);
290 BUG_ON(ret);
291 put_free_pages(blkif, pages, segs_to_unmap);
292 segs_to_unmap = 0;
293 }
294
295 rb_erase(&persistent_gnt->node, root);
296 kfree(persistent_gnt);
297 num--;
298 }
299 BUG_ON(num != 0);
300 }
301
302 static void unmap_purged_grants(struct work_struct *work)
303 {
304 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
305 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
306 struct persistent_gnt *persistent_gnt;
307 int ret, segs_to_unmap = 0;
308 struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work);
309
310 while(!list_empty(&blkif->persistent_purge_list)) {
311 persistent_gnt = list_first_entry(&blkif->persistent_purge_list,
312 struct persistent_gnt,
313 remove_node);
314 list_del(&persistent_gnt->remove_node);
315
316 gnttab_set_unmap_op(&unmap[segs_to_unmap],
317 vaddr(persistent_gnt->page),
318 GNTMAP_host_map,
319 persistent_gnt->handle);
320
321 pages[segs_to_unmap] = persistent_gnt->page;
322
323 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
324 ret = gnttab_unmap_refs(unmap, NULL, pages,
325 segs_to_unmap);
326 BUG_ON(ret);
327 put_free_pages(blkif, pages, segs_to_unmap);
328 segs_to_unmap = 0;
329 }
330 kfree(persistent_gnt);
331 }
332 if (segs_to_unmap > 0) {
333 ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap);
334 BUG_ON(ret);
335 put_free_pages(blkif, pages, segs_to_unmap);
336 }
337 }
338
339 static void purge_persistent_gnt(struct xen_blkif *blkif)
340 {
341 struct persistent_gnt *persistent_gnt;
342 struct rb_node *n;
343 unsigned int num_clean, total;
344 bool scan_used = false, clean_used = false;
345 struct rb_root *root;
346
347 if (blkif->persistent_gnt_c < xen_blkif_max_pgrants ||
348 (blkif->persistent_gnt_c == xen_blkif_max_pgrants &&
349 !blkif->vbd.overflow_max_grants)) {
350 return;
351 }
352
353 if (work_pending(&blkif->persistent_purge_work)) {
354 pr_alert_ratelimited(DRV_PFX "Scheduled work from previous purge is still pending, cannot purge list\n");
355 return;
356 }
357
358 num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
359 num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean;
360 num_clean = min(blkif->persistent_gnt_c, num_clean);
361 if ((num_clean == 0) ||
362 (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use))))
363 return;
364
365 /*
366 * At this point, we can assure that there will be no calls
367 * to get_persistent_grant (because we are executing this code from
368 * xen_blkif_schedule), there can only be calls to put_persistent_gnt,
369 * which means that the number of currently used grants will go down,
370 * but never up, so we will always be able to remove the requested
371 * number of grants.
372 */
373
374 total = num_clean;
375
376 pr_debug(DRV_PFX "Going to purge %u persistent grants\n", num_clean);
377
378 INIT_LIST_HEAD(&blkif->persistent_purge_list);
379 root = &blkif->persistent_gnts;
380 purge_list:
381 foreach_grant_safe(persistent_gnt, n, root, node) {
382 BUG_ON(persistent_gnt->handle ==
383 BLKBACK_INVALID_HANDLE);
384
385 if (clean_used) {
386 clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
387 continue;
388 }
389
390 if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
391 continue;
392 if (!scan_used &&
393 (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags)))
394 continue;
395
396 rb_erase(&persistent_gnt->node, root);
397 list_add(&persistent_gnt->remove_node,
398 &blkif->persistent_purge_list);
399 if (--num_clean == 0)
400 goto finished;
401 }
402 /*
403 * If we get here it means we also need to start cleaning
404 * grants that were used since last purge in order to cope
405 * with the requested num
406 */
407 if (!scan_used && !clean_used) {
408 pr_debug(DRV_PFX "Still missing %u purged frames\n", num_clean);
409 scan_used = true;
410 goto purge_list;
411 }
412 finished:
413 if (!clean_used) {
414 pr_debug(DRV_PFX "Finished scanning for grants to clean, removing used flag\n");
415 clean_used = true;
416 goto purge_list;
417 }
418
419 blkif->persistent_gnt_c -= (total - num_clean);
420 blkif->vbd.overflow_max_grants = 0;
421
422 /* We can defer this work */
423 INIT_WORK(&blkif->persistent_purge_work, unmap_purged_grants);
424 schedule_work(&blkif->persistent_purge_work);
425 pr_debug(DRV_PFX "Purged %u/%u\n", (total - num_clean), total);
426 return;
427 }
428
429 /*
430 * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
431 */
432 static struct pending_req *alloc_req(struct xen_blkif *blkif)
433 {
434 struct pending_req *req = NULL;
435 unsigned long flags;
436
437 spin_lock_irqsave(&blkif->pending_free_lock, flags);
438 if (!list_empty(&blkif->pending_free)) {
439 req = list_entry(blkif->pending_free.next, struct pending_req,
440 free_list);
441 list_del(&req->free_list);
442 }
443 spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
444 return req;
445 }
446
447 /*
448 * Return the 'pending_req' structure back to the freepool. We also
449 * wake up the thread if it was waiting for a free page.
450 */
451 static void free_req(struct xen_blkif *blkif, struct pending_req *req)
452 {
453 unsigned long flags;
454 int was_empty;
455
456 spin_lock_irqsave(&blkif->pending_free_lock, flags);
457 was_empty = list_empty(&blkif->pending_free);
458 list_add(&req->free_list, &blkif->pending_free);
459 spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
460 if (was_empty)
461 wake_up(&blkif->pending_free_wq);
462 }
463
464 /*
465 * Routines for managing virtual block devices (vbds).
466 */
467 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
468 int operation)
469 {
470 struct xen_vbd *vbd = &blkif->vbd;
471 int rc = -EACCES;
472
473 if ((operation != READ) && vbd->readonly)
474 goto out;
475
476 if (likely(req->nr_sects)) {
477 blkif_sector_t end = req->sector_number + req->nr_sects;
478
479 if (unlikely(end < req->sector_number))
480 goto out;
481 if (unlikely(end > vbd_sz(vbd)))
482 goto out;
483 }
484
485 req->dev = vbd->pdevice;
486 req->bdev = vbd->bdev;
487 rc = 0;
488
489 out:
490 return rc;
491 }
492
493 static void xen_vbd_resize(struct xen_blkif *blkif)
494 {
495 struct xen_vbd *vbd = &blkif->vbd;
496 struct xenbus_transaction xbt;
497 int err;
498 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be);
499 unsigned long long new_size = vbd_sz(vbd);
500
501 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n",
502 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
503 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size);
504 vbd->size = new_size;
505 again:
506 err = xenbus_transaction_start(&xbt);
507 if (err) {
508 pr_warn(DRV_PFX "Error starting transaction");
509 return;
510 }
511 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
512 (unsigned long long)vbd_sz(vbd));
513 if (err) {
514 pr_warn(DRV_PFX "Error writing new size");
515 goto abort;
516 }
517 /*
518 * Write the current state; we will use this to synchronize
519 * the front-end. If the current state is "connected" the
520 * front-end will get the new size information online.
521 */
522 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
523 if (err) {
524 pr_warn(DRV_PFX "Error writing the state");
525 goto abort;
526 }
527
528 err = xenbus_transaction_end(xbt, 0);
529 if (err == -EAGAIN)
530 goto again;
531 if (err)
532 pr_warn(DRV_PFX "Error ending transaction");
533 return;
534 abort:
535 xenbus_transaction_end(xbt, 1);
536 }
537
538 /*
539 * Notification from the guest OS.
540 */
541 static void blkif_notify_work(struct xen_blkif *blkif)
542 {
543 blkif->waiting_reqs = 1;
544 wake_up(&blkif->wq);
545 }
546
547 irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
548 {
549 blkif_notify_work(dev_id);
550 return IRQ_HANDLED;
551 }
552
553 /*
554 * SCHEDULER FUNCTIONS
555 */
556
557 static void print_stats(struct xen_blkif *blkif)
558 {
559 pr_info("xen-blkback (%s): oo %3llu | rd %4llu | wr %4llu | f %4llu"
560 " | ds %4llu | pg: %4u/%4d\n",
561 current->comm, blkif->st_oo_req,
562 blkif->st_rd_req, blkif->st_wr_req,
563 blkif->st_f_req, blkif->st_ds_req,
564 blkif->persistent_gnt_c,
565 xen_blkif_max_pgrants);
566 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
567 blkif->st_rd_req = 0;
568 blkif->st_wr_req = 0;
569 blkif->st_oo_req = 0;
570 blkif->st_ds_req = 0;
571 }
572
573 int xen_blkif_schedule(void *arg)
574 {
575 struct xen_blkif *blkif = arg;
576 struct xen_vbd *vbd = &blkif->vbd;
577 unsigned long timeout;
578 int ret;
579
580 xen_blkif_get(blkif);
581
582 while (!kthread_should_stop()) {
583 if (try_to_freeze())
584 continue;
585 if (unlikely(vbd->size != vbd_sz(vbd)))
586 xen_vbd_resize(blkif);
587
588 timeout = msecs_to_jiffies(LRU_INTERVAL);
589
590 timeout = wait_event_interruptible_timeout(
591 blkif->wq,
592 blkif->waiting_reqs || kthread_should_stop(),
593 timeout);
594 if (timeout == 0)
595 goto purge_gnt_list;
596 timeout = wait_event_interruptible_timeout(
597 blkif->pending_free_wq,
598 !list_empty(&blkif->pending_free) ||
599 kthread_should_stop(),
600 timeout);
601 if (timeout == 0)
602 goto purge_gnt_list;
603
604 blkif->waiting_reqs = 0;
605 smp_mb(); /* clear flag *before* checking for work */
606
607 ret = do_block_io_op(blkif);
608 if (ret > 0)
609 blkif->waiting_reqs = 1;
610 if (ret == -EACCES)
611 wait_event_interruptible(blkif->shutdown_wq,
612 kthread_should_stop());
613
614 purge_gnt_list:
615 if (blkif->vbd.feature_gnt_persistent &&
616 time_after(jiffies, blkif->next_lru)) {
617 purge_persistent_gnt(blkif);
618 blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL);
619 }
620
621 /* Shrink if we have more than xen_blkif_max_buffer_pages */
622 shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages);
623
624 if (log_stats && time_after(jiffies, blkif->st_print))
625 print_stats(blkif);
626 }
627
628 /* Since we are shutting down remove all pages from the buffer */
629 shrink_free_pagepool(blkif, 0 /* All */);
630
631 /* Free all persistent grant pages */
632 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
633 free_persistent_gnts(blkif, &blkif->persistent_gnts,
634 blkif->persistent_gnt_c);
635
636 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
637 blkif->persistent_gnt_c = 0;
638
639 if (log_stats)
640 print_stats(blkif);
641
642 blkif->xenblkd = NULL;
643 xen_blkif_put(blkif);
644
645 return 0;
646 }
647
648 /*
649 * Unmap the grant references, and also remove the M2P over-rides
650 * used in the 'pending_req'.
651 */
652 static void xen_blkbk_unmap(struct xen_blkif *blkif,
653 struct grant_page *pages[],
654 int num)
655 {
656 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
657 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
658 unsigned int i, invcount = 0;
659 int ret;
660
661 for (i = 0; i < num; i++) {
662 if (pages[i]->persistent_gnt != NULL) {
663 put_persistent_gnt(blkif, pages[i]->persistent_gnt);
664 continue;
665 }
666 if (pages[i]->handle == BLKBACK_INVALID_HANDLE)
667 continue;
668 unmap_pages[invcount] = pages[i]->page;
669 gnttab_set_unmap_op(&unmap[invcount], vaddr(pages[i]->page),
670 GNTMAP_host_map, pages[i]->handle);
671 pages[i]->handle = BLKBACK_INVALID_HANDLE;
672 if (++invcount == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
673 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages,
674 invcount);
675 BUG_ON(ret);
676 put_free_pages(blkif, unmap_pages, invcount);
677 invcount = 0;
678 }
679 }
680 if (invcount) {
681 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
682 BUG_ON(ret);
683 put_free_pages(blkif, unmap_pages, invcount);
684 }
685 }
686
687 static int xen_blkbk_map(struct xen_blkif *blkif,
688 struct grant_page *pages[],
689 int num, bool ro)
690 {
691 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
692 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
693 struct persistent_gnt *persistent_gnt = NULL;
694 phys_addr_t addr = 0;
695 int i, seg_idx, new_map_idx;
696 int segs_to_map = 0;
697 int ret = 0;
698 int last_map = 0, map_until = 0;
699 int use_persistent_gnts;
700
701 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
702
703 /*
704 * Fill out preq.nr_sects with proper amount of sectors, and setup
705 * assign map[..] with the PFN of the page in our domain with the
706 * corresponding grant reference for each page.
707 */
708 again:
709 for (i = map_until; i < num; i++) {
710 uint32_t flags;
711
712 if (use_persistent_gnts)
713 persistent_gnt = get_persistent_gnt(
714 blkif,
715 pages[i]->gref);
716
717 if (persistent_gnt) {
718 /*
719 * We are using persistent grants and
720 * the grant is already mapped
721 */
722 pages[i]->page = persistent_gnt->page;
723 pages[i]->persistent_gnt = persistent_gnt;
724 } else {
725 if (get_free_page(blkif, &pages[i]->page))
726 goto out_of_memory;
727 addr = vaddr(pages[i]->page);
728 pages_to_gnt[segs_to_map] = pages[i]->page;
729 pages[i]->persistent_gnt = NULL;
730 flags = GNTMAP_host_map;
731 if (!use_persistent_gnts && ro)
732 flags |= GNTMAP_readonly;
733 gnttab_set_map_op(&map[segs_to_map++], addr,
734 flags, pages[i]->gref,
735 blkif->domid);
736 }
737 map_until = i + 1;
738 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST)
739 break;
740 }
741
742 if (segs_to_map) {
743 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
744 BUG_ON(ret);
745 }
746
747 /*
748 * Now swizzle the MFN in our domain with the MFN from the other domain
749 * so that when we access vaddr(pending_req,i) it has the contents of
750 * the page from the other domain.
751 */
752 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) {
753 if (!pages[seg_idx]->persistent_gnt) {
754 /* This is a newly mapped grant */
755 BUG_ON(new_map_idx >= segs_to_map);
756 if (unlikely(map[new_map_idx].status != 0)) {
757 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
758 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE;
759 ret |= 1;
760 goto next;
761 }
762 pages[seg_idx]->handle = map[new_map_idx].handle;
763 } else {
764 continue;
765 }
766 if (use_persistent_gnts &&
767 blkif->persistent_gnt_c < xen_blkif_max_pgrants) {
768 /*
769 * We are using persistent grants, the grant is
770 * not mapped but we might have room for it.
771 */
772 persistent_gnt = kmalloc(sizeof(struct persistent_gnt),
773 GFP_KERNEL);
774 if (!persistent_gnt) {
775 /*
776 * If we don't have enough memory to
777 * allocate the persistent_gnt struct
778 * map this grant non-persistenly
779 */
780 goto next;
781 }
782 persistent_gnt->gnt = map[new_map_idx].ref;
783 persistent_gnt->handle = map[new_map_idx].handle;
784 persistent_gnt->page = pages[seg_idx]->page;
785 if (add_persistent_gnt(blkif,
786 persistent_gnt)) {
787 kfree(persistent_gnt);
788 persistent_gnt = NULL;
789 goto next;
790 }
791 pages[seg_idx]->persistent_gnt = persistent_gnt;
792 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
793 persistent_gnt->gnt, blkif->persistent_gnt_c,
794 xen_blkif_max_pgrants);
795 goto next;
796 }
797 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) {
798 blkif->vbd.overflow_max_grants = 1;
799 pr_debug(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n",
800 blkif->domid, blkif->vbd.handle);
801 }
802 /*
803 * We could not map this grant persistently, so use it as
804 * a non-persistent grant.
805 */
806 next:
807 new_map_idx++;
808 }
809 segs_to_map = 0;
810 last_map = map_until;
811 if (map_until != num)
812 goto again;
813
814 return ret;
815
816 out_of_memory:
817 pr_alert(DRV_PFX "%s: out of memory\n", __func__);
818 put_free_pages(blkif, pages_to_gnt, segs_to_map);
819 return -ENOMEM;
820 }
821
822 static int xen_blkbk_map_seg(struct pending_req *pending_req)
823 {
824 int rc;
825
826 rc = xen_blkbk_map(pending_req->blkif, pending_req->segments,
827 pending_req->nr_pages,
828 (pending_req->operation != BLKIF_OP_READ));
829
830 return rc;
831 }
832
833 static int xen_blkbk_parse_indirect(struct blkif_request *req,
834 struct pending_req *pending_req,
835 struct seg_buf seg[],
836 struct phys_req *preq)
837 {
838 struct grant_page **pages = pending_req->indirect_pages;
839 struct xen_blkif *blkif = pending_req->blkif;
840 int indirect_grefs, rc, n, nseg, i;
841 struct blkif_request_segment_aligned *segments = NULL;
842
843 nseg = pending_req->nr_pages;
844 indirect_grefs = INDIRECT_PAGES(nseg);
845 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
846
847 for (i = 0; i < indirect_grefs; i++)
848 pages[i]->gref = req->u.indirect.indirect_grefs[i];
849
850 rc = xen_blkbk_map(blkif, pages, indirect_grefs, true);
851 if (rc)
852 goto unmap;
853
854 for (n = 0, i = 0; n < nseg; n++) {
855 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) {
856 /* Map indirect segments */
857 if (segments)
858 kunmap_atomic(segments);
859 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page);
860 }
861 i = n % SEGS_PER_INDIRECT_FRAME;
862 pending_req->segments[n]->gref = segments[i].gref;
863 seg[n].nsec = segments[i].last_sect -
864 segments[i].first_sect + 1;
865 seg[n].offset = (segments[i].first_sect << 9);
866 if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) ||
867 (segments[i].last_sect < segments[i].first_sect)) {
868 rc = -EINVAL;
869 goto unmap;
870 }
871 preq->nr_sects += seg[n].nsec;
872 }
873
874 unmap:
875 if (segments)
876 kunmap_atomic(segments);
877 xen_blkbk_unmap(blkif, pages, indirect_grefs);
878 return rc;
879 }
880
881 static int dispatch_discard_io(struct xen_blkif *blkif,
882 struct blkif_request *req)
883 {
884 int err = 0;
885 int status = BLKIF_RSP_OKAY;
886 struct block_device *bdev = blkif->vbd.bdev;
887 unsigned long secure;
888 struct phys_req preq;
889
890 preq.sector_number = req->u.discard.sector_number;
891 preq.nr_sects = req->u.discard.nr_sectors;
892
893 err = xen_vbd_translate(&preq, blkif, WRITE);
894 if (err) {
895 pr_warn(DRV_PFX "access denied: DISCARD [%llu->%llu] on dev=%04x\n",
896 preq.sector_number,
897 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
898 goto fail_response;
899 }
900 blkif->st_ds_req++;
901
902 xen_blkif_get(blkif);
903 secure = (blkif->vbd.discard_secure &&
904 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
905 BLKDEV_DISCARD_SECURE : 0;
906
907 err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
908 req->u.discard.nr_sectors,
909 GFP_KERNEL, secure);
910 fail_response:
911 if (err == -EOPNOTSUPP) {
912 pr_debug(DRV_PFX "discard op failed, not supported\n");
913 status = BLKIF_RSP_EOPNOTSUPP;
914 } else if (err)
915 status = BLKIF_RSP_ERROR;
916
917 make_response(blkif, req->u.discard.id, req->operation, status);
918 xen_blkif_put(blkif);
919 return err;
920 }
921
922 static int dispatch_other_io(struct xen_blkif *blkif,
923 struct blkif_request *req,
924 struct pending_req *pending_req)
925 {
926 free_req(blkif, pending_req);
927 make_response(blkif, req->u.other.id, req->operation,
928 BLKIF_RSP_EOPNOTSUPP);
929 return -EIO;
930 }
931
932 static void xen_blk_drain_io(struct xen_blkif *blkif)
933 {
934 atomic_set(&blkif->drain, 1);
935 do {
936 /* The initial value is one, and one refcnt taken at the
937 * start of the xen_blkif_schedule thread. */
938 if (atomic_read(&blkif->refcnt) <= 2)
939 break;
940 wait_for_completion_interruptible_timeout(
941 &blkif->drain_complete, HZ);
942
943 if (!atomic_read(&blkif->drain))
944 break;
945 } while (!kthread_should_stop());
946 atomic_set(&blkif->drain, 0);
947 }
948
949 /*
950 * Completion callback on the bio's. Called as bh->b_end_io()
951 */
952
953 static void __end_block_io_op(struct pending_req *pending_req, int error)
954 {
955 /* An error fails the entire request. */
956 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) &&
957 (error == -EOPNOTSUPP)) {
958 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n");
959 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
960 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
961 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
962 (error == -EOPNOTSUPP)) {
963 pr_debug(DRV_PFX "write barrier op failed, not supported\n");
964 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
965 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
966 } else if (error) {
967 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation,"
968 " error=%d\n", error);
969 pending_req->status = BLKIF_RSP_ERROR;
970 }
971
972 /*
973 * If all of the bio's have completed it is time to unmap
974 * the grant references associated with 'request' and provide
975 * the proper response on the ring.
976 */
977 if (atomic_dec_and_test(&pending_req->pendcnt)) {
978 xen_blkbk_unmap(pending_req->blkif,
979 pending_req->segments,
980 pending_req->nr_pages);
981 make_response(pending_req->blkif, pending_req->id,
982 pending_req->operation, pending_req->status);
983 xen_blkif_put(pending_req->blkif);
984 if (atomic_read(&pending_req->blkif->refcnt) <= 2) {
985 if (atomic_read(&pending_req->blkif->drain))
986 complete(&pending_req->blkif->drain_complete);
987 }
988 free_req(pending_req->blkif, pending_req);
989 }
990 }
991
992 /*
993 * bio callback.
994 */
995 static void end_block_io_op(struct bio *bio, int error)
996 {
997 __end_block_io_op(bio->bi_private, error);
998 bio_put(bio);
999 }
1000
1001
1002
1003 /*
1004 * Function to copy the from the ring buffer the 'struct blkif_request'
1005 * (which has the sectors we want, number of them, grant references, etc),
1006 * and transmute it to the block API to hand it over to the proper block disk.
1007 */
1008 static int
1009 __do_block_io_op(struct xen_blkif *blkif)
1010 {
1011 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1012 struct blkif_request req;
1013 struct pending_req *pending_req;
1014 RING_IDX rc, rp;
1015 int more_to_do = 0;
1016
1017 rc = blk_rings->common.req_cons;
1018 rp = blk_rings->common.sring->req_prod;
1019 rmb(); /* Ensure we see queued requests up to 'rp'. */
1020
1021 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) {
1022 rc = blk_rings->common.rsp_prod_pvt;
1023 pr_warn(DRV_PFX "Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n",
1024 rp, rc, rp - rc, blkif->vbd.pdevice);
1025 return -EACCES;
1026 }
1027 while (rc != rp) {
1028
1029 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
1030 break;
1031
1032 if (kthread_should_stop()) {
1033 more_to_do = 1;
1034 break;
1035 }
1036
1037 pending_req = alloc_req(blkif);
1038 if (NULL == pending_req) {
1039 blkif->st_oo_req++;
1040 more_to_do = 1;
1041 break;
1042 }
1043
1044 switch (blkif->blk_protocol) {
1045 case BLKIF_PROTOCOL_NATIVE:
1046 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
1047 break;
1048 case BLKIF_PROTOCOL_X86_32:
1049 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
1050 break;
1051 case BLKIF_PROTOCOL_X86_64:
1052 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
1053 break;
1054 default:
1055 BUG();
1056 }
1057 blk_rings->common.req_cons = ++rc; /* before make_response() */
1058
1059 /* Apply all sanity checks to /private copy/ of request. */
1060 barrier();
1061
1062 switch (req.operation) {
1063 case BLKIF_OP_READ:
1064 case BLKIF_OP_WRITE:
1065 case BLKIF_OP_WRITE_BARRIER:
1066 case BLKIF_OP_FLUSH_DISKCACHE:
1067 case BLKIF_OP_INDIRECT:
1068 if (dispatch_rw_block_io(blkif, &req, pending_req))
1069 goto done;
1070 break;
1071 case BLKIF_OP_DISCARD:
1072 free_req(blkif, pending_req);
1073 if (dispatch_discard_io(blkif, &req))
1074 goto done;
1075 break;
1076 default:
1077 if (dispatch_other_io(blkif, &req, pending_req))
1078 goto done;
1079 break;
1080 }
1081
1082 /* Yield point for this unbounded loop. */
1083 cond_resched();
1084 }
1085 done:
1086 return more_to_do;
1087 }
1088
1089 static int
1090 do_block_io_op(struct xen_blkif *blkif)
1091 {
1092 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1093 int more_to_do;
1094
1095 do {
1096 more_to_do = __do_block_io_op(blkif);
1097 if (more_to_do)
1098 break;
1099
1100 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
1101 } while (more_to_do);
1102
1103 return more_to_do;
1104 }
1105 /*
1106 * Transmutation of the 'struct blkif_request' to a proper 'struct bio'
1107 * and call the 'submit_bio' to pass it to the underlying storage.
1108 */
1109 static int dispatch_rw_block_io(struct xen_blkif *blkif,
1110 struct blkif_request *req,
1111 struct pending_req *pending_req)
1112 {
1113 struct phys_req preq;
1114 struct seg_buf *seg = pending_req->seg;
1115 unsigned int nseg;
1116 struct bio *bio = NULL;
1117 struct bio **biolist = pending_req->biolist;
1118 int i, nbio = 0;
1119 int operation;
1120 struct blk_plug plug;
1121 bool drain = false;
1122 struct grant_page **pages = pending_req->segments;
1123 unsigned short req_operation;
1124
1125 req_operation = req->operation == BLKIF_OP_INDIRECT ?
1126 req->u.indirect.indirect_op : req->operation;
1127 if ((req->operation == BLKIF_OP_INDIRECT) &&
1128 (req_operation != BLKIF_OP_READ) &&
1129 (req_operation != BLKIF_OP_WRITE)) {
1130 pr_debug(DRV_PFX "Invalid indirect operation (%u)\n",
1131 req_operation);
1132 goto fail_response;
1133 }
1134
1135 switch (req_operation) {
1136 case BLKIF_OP_READ:
1137 blkif->st_rd_req++;
1138 operation = READ;
1139 break;
1140 case BLKIF_OP_WRITE:
1141 blkif->st_wr_req++;
1142 operation = WRITE_ODIRECT;
1143 break;
1144 case BLKIF_OP_WRITE_BARRIER:
1145 drain = true;
1146 case BLKIF_OP_FLUSH_DISKCACHE:
1147 blkif->st_f_req++;
1148 operation = WRITE_FLUSH;
1149 break;
1150 default:
1151 operation = 0; /* make gcc happy */
1152 goto fail_response;
1153 break;
1154 }
1155
1156 /* Check that the number of segments is sane. */
1157 nseg = req->operation == BLKIF_OP_INDIRECT ?
1158 req->u.indirect.nr_segments : req->u.rw.nr_segments;
1159
1160 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
1161 unlikely((req->operation != BLKIF_OP_INDIRECT) &&
1162 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) ||
1163 unlikely((req->operation == BLKIF_OP_INDIRECT) &&
1164 (nseg > MAX_INDIRECT_SEGMENTS))) {
1165 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
1166 nseg);
1167 /* Haven't submitted any bio's yet. */
1168 goto fail_response;
1169 }
1170
1171 preq.nr_sects = 0;
1172
1173 pending_req->blkif = blkif;
1174 pending_req->id = req->u.rw.id;
1175 pending_req->operation = req_operation;
1176 pending_req->status = BLKIF_RSP_OKAY;
1177 pending_req->nr_pages = nseg;
1178
1179 if (req->operation != BLKIF_OP_INDIRECT) {
1180 preq.dev = req->u.rw.handle;
1181 preq.sector_number = req->u.rw.sector_number;
1182 for (i = 0; i < nseg; i++) {
1183 pages[i]->gref = req->u.rw.seg[i].gref;
1184 seg[i].nsec = req->u.rw.seg[i].last_sect -
1185 req->u.rw.seg[i].first_sect + 1;
1186 seg[i].offset = (req->u.rw.seg[i].first_sect << 9);
1187 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
1188 (req->u.rw.seg[i].last_sect <
1189 req->u.rw.seg[i].first_sect))
1190 goto fail_response;
1191 preq.nr_sects += seg[i].nsec;
1192 }
1193 } else {
1194 preq.dev = req->u.indirect.handle;
1195 preq.sector_number = req->u.indirect.sector_number;
1196 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq))
1197 goto fail_response;
1198 }
1199
1200 if (xen_vbd_translate(&preq, blkif, operation) != 0) {
1201 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n",
1202 operation == READ ? "read" : "write",
1203 preq.sector_number,
1204 preq.sector_number + preq.nr_sects,
1205 blkif->vbd.pdevice);
1206 goto fail_response;
1207 }
1208
1209 /*
1210 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev
1211 * is set there.
1212 */
1213 for (i = 0; i < nseg; i++) {
1214 if (((int)preq.sector_number|(int)seg[i].nsec) &
1215 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
1216 pr_debug(DRV_PFX "Misaligned I/O request from domain %d",
1217 blkif->domid);
1218 goto fail_response;
1219 }
1220 }
1221
1222 /* Wait on all outstanding I/O's and once that has been completed
1223 * issue the WRITE_FLUSH.
1224 */
1225 if (drain)
1226 xen_blk_drain_io(pending_req->blkif);
1227
1228 /*
1229 * If we have failed at this point, we need to undo the M2P override,
1230 * set gnttab_set_unmap_op on all of the grant references and perform
1231 * the hypercall to unmap the grants - that is all done in
1232 * xen_blkbk_unmap.
1233 */
1234 if (xen_blkbk_map_seg(pending_req))
1235 goto fail_flush;
1236
1237 /*
1238 * This corresponding xen_blkif_put is done in __end_block_io_op, or
1239 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
1240 */
1241 xen_blkif_get(blkif);
1242
1243 for (i = 0; i < nseg; i++) {
1244 while ((bio == NULL) ||
1245 (bio_add_page(bio,
1246 pages[i]->page,
1247 seg[i].nsec << 9,
1248 seg[i].offset) == 0)) {
1249
1250 int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES);
1251 bio = bio_alloc(GFP_KERNEL, nr_iovecs);
1252 if (unlikely(bio == NULL))
1253 goto fail_put_bio;
1254
1255 biolist[nbio++] = bio;
1256 bio->bi_bdev = preq.bdev;
1257 bio->bi_private = pending_req;
1258 bio->bi_end_io = end_block_io_op;
1259 bio->bi_sector = preq.sector_number;
1260 }
1261
1262 preq.sector_number += seg[i].nsec;
1263 }
1264
1265 /* This will be hit if the operation was a flush or discard. */
1266 if (!bio) {
1267 BUG_ON(operation != WRITE_FLUSH);
1268
1269 bio = bio_alloc(GFP_KERNEL, 0);
1270 if (unlikely(bio == NULL))
1271 goto fail_put_bio;
1272
1273 biolist[nbio++] = bio;
1274 bio->bi_bdev = preq.bdev;
1275 bio->bi_private = pending_req;
1276 bio->bi_end_io = end_block_io_op;
1277 }
1278
1279 atomic_set(&pending_req->pendcnt, nbio);
1280 blk_start_plug(&plug);
1281
1282 for (i = 0; i < nbio; i++)
1283 submit_bio(operation, biolist[i]);
1284
1285 /* Let the I/Os go.. */
1286 blk_finish_plug(&plug);
1287
1288 if (operation == READ)
1289 blkif->st_rd_sect += preq.nr_sects;
1290 else if (operation & WRITE)
1291 blkif->st_wr_sect += preq.nr_sects;
1292
1293 return 0;
1294
1295 fail_flush:
1296 xen_blkbk_unmap(blkif, pending_req->segments,
1297 pending_req->nr_pages);
1298 fail_response:
1299 /* Haven't submitted any bio's yet. */
1300 make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR);
1301 free_req(blkif, pending_req);
1302 msleep(1); /* back off a bit */
1303 return -EIO;
1304
1305 fail_put_bio:
1306 for (i = 0; i < nbio; i++)
1307 bio_put(biolist[i]);
1308 atomic_set(&pending_req->pendcnt, 1);
1309 __end_block_io_op(pending_req, -EINVAL);
1310 msleep(1); /* back off a bit */
1311 return -EIO;
1312 }
1313
1314
1315
1316 /*
1317 * Put a response on the ring on how the operation fared.
1318 */
1319 static void make_response(struct xen_blkif *blkif, u64 id,
1320 unsigned short op, int st)
1321 {
1322 struct blkif_response resp;
1323 unsigned long flags;
1324 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1325 int notify;
1326
1327 resp.id = id;
1328 resp.operation = op;
1329 resp.status = st;
1330
1331 spin_lock_irqsave(&blkif->blk_ring_lock, flags);
1332 /* Place on the response ring for the relevant domain. */
1333 switch (blkif->blk_protocol) {
1334 case BLKIF_PROTOCOL_NATIVE:
1335 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
1336 &resp, sizeof(resp));
1337 break;
1338 case BLKIF_PROTOCOL_X86_32:
1339 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
1340 &resp, sizeof(resp));
1341 break;
1342 case BLKIF_PROTOCOL_X86_64:
1343 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
1344 &resp, sizeof(resp));
1345 break;
1346 default:
1347 BUG();
1348 }
1349 blk_rings->common.rsp_prod_pvt++;
1350 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
1351 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
1352 if (notify)
1353 notify_remote_via_irq(blkif->irq);
1354 }
1355
1356 static int __init xen_blkif_init(void)
1357 {
1358 int rc = 0;
1359
1360 if (!xen_domain())
1361 return -ENODEV;
1362
1363 rc = xen_blkif_interface_init();
1364 if (rc)
1365 goto failed_init;
1366
1367 rc = xen_blkif_xenbus_init();
1368 if (rc)
1369 goto failed_init;
1370
1371 failed_init:
1372 return rc;
1373 }
1374
1375 module_init(xen_blkif_init);
1376
1377 MODULE_LICENSE("Dual BSD/GPL");
1378 MODULE_ALIAS("xen-backend:vbd");
CRIS linux kernel tree