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xen-blkback: init persistent_purge_work work_struct
[deliverable/linux.git] / drivers / block / xen-blkback / blkback.c
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 void xen_blkbk_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 BUG_ON(!list_empty(&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 schedule_work(&blkif->persistent_purge_work);
424 pr_debug(DRV_PFX "Purged %u/%u\n", (total - num_clean), total);
425 return;
426 }
427
428 /*
429 * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
430 */
431 static struct pending_req *alloc_req(struct xen_blkif *blkif)
432 {
433 struct pending_req *req = NULL;
434 unsigned long flags;
435
436 spin_lock_irqsave(&blkif->pending_free_lock, flags);
437 if (!list_empty(&blkif->pending_free)) {
438 req = list_entry(blkif->pending_free.next, struct pending_req,
439 free_list);
440 list_del(&req->free_list);
441 }
442 spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
443 return req;
444 }
445
446 /*
447 * Return the 'pending_req' structure back to the freepool. We also
448 * wake up the thread if it was waiting for a free page.
449 */
450 static void free_req(struct xen_blkif *blkif, struct pending_req *req)
451 {
452 unsigned long flags;
453 int was_empty;
454
455 spin_lock_irqsave(&blkif->pending_free_lock, flags);
456 was_empty = list_empty(&blkif->pending_free);
457 list_add(&req->free_list, &blkif->pending_free);
458 spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
459 if (was_empty)
460 wake_up(&blkif->pending_free_wq);
461 }
462
463 /*
464 * Routines for managing virtual block devices (vbds).
465 */
466 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
467 int operation)
468 {
469 struct xen_vbd *vbd = &blkif->vbd;
470 int rc = -EACCES;
471
472 if ((operation != READ) && vbd->readonly)
473 goto out;
474
475 if (likely(req->nr_sects)) {
476 blkif_sector_t end = req->sector_number + req->nr_sects;
477
478 if (unlikely(end < req->sector_number))
479 goto out;
480 if (unlikely(end > vbd_sz(vbd)))
481 goto out;
482 }
483
484 req->dev = vbd->pdevice;
485 req->bdev = vbd->bdev;
486 rc = 0;
487
488 out:
489 return rc;
490 }
491
492 static void xen_vbd_resize(struct xen_blkif *blkif)
493 {
494 struct xen_vbd *vbd = &blkif->vbd;
495 struct xenbus_transaction xbt;
496 int err;
497 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be);
498 unsigned long long new_size = vbd_sz(vbd);
499
500 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n",
501 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
502 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size);
503 vbd->size = new_size;
504 again:
505 err = xenbus_transaction_start(&xbt);
506 if (err) {
507 pr_warn(DRV_PFX "Error starting transaction");
508 return;
509 }
510 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
511 (unsigned long long)vbd_sz(vbd));
512 if (err) {
513 pr_warn(DRV_PFX "Error writing new size");
514 goto abort;
515 }
516 /*
517 * Write the current state; we will use this to synchronize
518 * the front-end. If the current state is "connected" the
519 * front-end will get the new size information online.
520 */
521 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
522 if (err) {
523 pr_warn(DRV_PFX "Error writing the state");
524 goto abort;
525 }
526
527 err = xenbus_transaction_end(xbt, 0);
528 if (err == -EAGAIN)
529 goto again;
530 if (err)
531 pr_warn(DRV_PFX "Error ending transaction");
532 return;
533 abort:
534 xenbus_transaction_end(xbt, 1);
535 }
536
537 /*
538 * Notification from the guest OS.
539 */
540 static void blkif_notify_work(struct xen_blkif *blkif)
541 {
542 blkif->waiting_reqs = 1;
543 wake_up(&blkif->wq);
544 }
545
546 irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
547 {
548 blkif_notify_work(dev_id);
549 return IRQ_HANDLED;
550 }
551
552 /*
553 * SCHEDULER FUNCTIONS
554 */
555
556 static void print_stats(struct xen_blkif *blkif)
557 {
558 pr_info("xen-blkback (%s): oo %3llu | rd %4llu | wr %4llu | f %4llu"
559 " | ds %4llu | pg: %4u/%4d\n",
560 current->comm, blkif->st_oo_req,
561 blkif->st_rd_req, blkif->st_wr_req,
562 blkif->st_f_req, blkif->st_ds_req,
563 blkif->persistent_gnt_c,
564 xen_blkif_max_pgrants);
565 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
566 blkif->st_rd_req = 0;
567 blkif->st_wr_req = 0;
568 blkif->st_oo_req = 0;
569 blkif->st_ds_req = 0;
570 }
571
572 int xen_blkif_schedule(void *arg)
573 {
574 struct xen_blkif *blkif = arg;
575 struct xen_vbd *vbd = &blkif->vbd;
576 unsigned long timeout;
577 int ret;
578
579 xen_blkif_get(blkif);
580
581 while (!kthread_should_stop()) {
582 if (try_to_freeze())
583 continue;
584 if (unlikely(vbd->size != vbd_sz(vbd)))
585 xen_vbd_resize(blkif);
586
587 timeout = msecs_to_jiffies(LRU_INTERVAL);
588
589 timeout = wait_event_interruptible_timeout(
590 blkif->wq,
591 blkif->waiting_reqs || kthread_should_stop(),
592 timeout);
593 if (timeout == 0)
594 goto purge_gnt_list;
595 timeout = wait_event_interruptible_timeout(
596 blkif->pending_free_wq,
597 !list_empty(&blkif->pending_free) ||
598 kthread_should_stop(),
599 timeout);
600 if (timeout == 0)
601 goto purge_gnt_list;
602
603 blkif->waiting_reqs = 0;
604 smp_mb(); /* clear flag *before* checking for work */
605
606 ret = do_block_io_op(blkif);
607 if (ret > 0)
608 blkif->waiting_reqs = 1;
609 if (ret == -EACCES)
610 wait_event_interruptible(blkif->shutdown_wq,
611 kthread_should_stop());
612
613 purge_gnt_list:
614 if (blkif->vbd.feature_gnt_persistent &&
615 time_after(jiffies, blkif->next_lru)) {
616 purge_persistent_gnt(blkif);
617 blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL);
618 }
619
620 /* Shrink if we have more than xen_blkif_max_buffer_pages */
621 shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages);
622
623 if (log_stats && time_after(jiffies, blkif->st_print))
624 print_stats(blkif);
625 }
626
627 /* Drain pending purge work */
628 flush_work(&blkif->persistent_purge_work);
629
630 if (log_stats)
631 print_stats(blkif);
632
633 blkif->xenblkd = NULL;
634 xen_blkif_put(blkif);
635
636 return 0;
637 }
638
639 /*
640 * Remove persistent grants and empty the pool of free pages
641 */
642 void xen_blkbk_free_caches(struct xen_blkif *blkif)
643 {
644 /* Free all persistent grant pages */
645 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
646 free_persistent_gnts(blkif, &blkif->persistent_gnts,
647 blkif->persistent_gnt_c);
648
649 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
650 blkif->persistent_gnt_c = 0;
651
652 /* Since we are shutting down remove all pages from the buffer */
653 shrink_free_pagepool(blkif, 0 /* All */);
654 }
655
656 /*
657 * Unmap the grant references, and also remove the M2P over-rides
658 * used in the 'pending_req'.
659 */
660 static void xen_blkbk_unmap(struct xen_blkif *blkif,
661 struct grant_page *pages[],
662 int num)
663 {
664 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
665 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
666 unsigned int i, invcount = 0;
667 int ret;
668
669 for (i = 0; i < num; i++) {
670 if (pages[i]->persistent_gnt != NULL) {
671 put_persistent_gnt(blkif, pages[i]->persistent_gnt);
672 continue;
673 }
674 if (pages[i]->handle == BLKBACK_INVALID_HANDLE)
675 continue;
676 unmap_pages[invcount] = pages[i]->page;
677 gnttab_set_unmap_op(&unmap[invcount], vaddr(pages[i]->page),
678 GNTMAP_host_map, pages[i]->handle);
679 pages[i]->handle = BLKBACK_INVALID_HANDLE;
680 if (++invcount == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
681 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages,
682 invcount);
683 BUG_ON(ret);
684 put_free_pages(blkif, unmap_pages, invcount);
685 invcount = 0;
686 }
687 }
688 if (invcount) {
689 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
690 BUG_ON(ret);
691 put_free_pages(blkif, unmap_pages, invcount);
692 }
693 }
694
695 static int xen_blkbk_map(struct xen_blkif *blkif,
696 struct grant_page *pages[],
697 int num, bool ro)
698 {
699 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
700 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
701 struct persistent_gnt *persistent_gnt = NULL;
702 phys_addr_t addr = 0;
703 int i, seg_idx, new_map_idx;
704 int segs_to_map = 0;
705 int ret = 0;
706 int last_map = 0, map_until = 0;
707 int use_persistent_gnts;
708
709 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
710
711 /*
712 * Fill out preq.nr_sects with proper amount of sectors, and setup
713 * assign map[..] with the PFN of the page in our domain with the
714 * corresponding grant reference for each page.
715 */
716 again:
717 for (i = map_until; i < num; i++) {
718 uint32_t flags;
719
720 if (use_persistent_gnts)
721 persistent_gnt = get_persistent_gnt(
722 blkif,
723 pages[i]->gref);
724
725 if (persistent_gnt) {
726 /*
727 * We are using persistent grants and
728 * the grant is already mapped
729 */
730 pages[i]->page = persistent_gnt->page;
731 pages[i]->persistent_gnt = persistent_gnt;
732 } else {
733 if (get_free_page(blkif, &pages[i]->page))
734 goto out_of_memory;
735 addr = vaddr(pages[i]->page);
736 pages_to_gnt[segs_to_map] = pages[i]->page;
737 pages[i]->persistent_gnt = NULL;
738 flags = GNTMAP_host_map;
739 if (!use_persistent_gnts && ro)
740 flags |= GNTMAP_readonly;
741 gnttab_set_map_op(&map[segs_to_map++], addr,
742 flags, pages[i]->gref,
743 blkif->domid);
744 }
745 map_until = i + 1;
746 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST)
747 break;
748 }
749
750 if (segs_to_map) {
751 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
752 BUG_ON(ret);
753 }
754
755 /*
756 * Now swizzle the MFN in our domain with the MFN from the other domain
757 * so that when we access vaddr(pending_req,i) it has the contents of
758 * the page from the other domain.
759 */
760 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) {
761 if (!pages[seg_idx]->persistent_gnt) {
762 /* This is a newly mapped grant */
763 BUG_ON(new_map_idx >= segs_to_map);
764 if (unlikely(map[new_map_idx].status != 0)) {
765 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
766 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE;
767 ret |= 1;
768 goto next;
769 }
770 pages[seg_idx]->handle = map[new_map_idx].handle;
771 } else {
772 continue;
773 }
774 if (use_persistent_gnts &&
775 blkif->persistent_gnt_c < xen_blkif_max_pgrants) {
776 /*
777 * We are using persistent grants, the grant is
778 * not mapped but we might have room for it.
779 */
780 persistent_gnt = kmalloc(sizeof(struct persistent_gnt),
781 GFP_KERNEL);
782 if (!persistent_gnt) {
783 /*
784 * If we don't have enough memory to
785 * allocate the persistent_gnt struct
786 * map this grant non-persistenly
787 */
788 goto next;
789 }
790 persistent_gnt->gnt = map[new_map_idx].ref;
791 persistent_gnt->handle = map[new_map_idx].handle;
792 persistent_gnt->page = pages[seg_idx]->page;
793 if (add_persistent_gnt(blkif,
794 persistent_gnt)) {
795 kfree(persistent_gnt);
796 persistent_gnt = NULL;
797 goto next;
798 }
799 pages[seg_idx]->persistent_gnt = persistent_gnt;
800 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
801 persistent_gnt->gnt, blkif->persistent_gnt_c,
802 xen_blkif_max_pgrants);
803 goto next;
804 }
805 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) {
806 blkif->vbd.overflow_max_grants = 1;
807 pr_debug(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n",
808 blkif->domid, blkif->vbd.handle);
809 }
810 /*
811 * We could not map this grant persistently, so use it as
812 * a non-persistent grant.
813 */
814 next:
815 new_map_idx++;
816 }
817 segs_to_map = 0;
818 last_map = map_until;
819 if (map_until != num)
820 goto again;
821
822 return ret;
823
824 out_of_memory:
825 pr_alert(DRV_PFX "%s: out of memory\n", __func__);
826 put_free_pages(blkif, pages_to_gnt, segs_to_map);
827 return -ENOMEM;
828 }
829
830 static int xen_blkbk_map_seg(struct pending_req *pending_req)
831 {
832 int rc;
833
834 rc = xen_blkbk_map(pending_req->blkif, pending_req->segments,
835 pending_req->nr_pages,
836 (pending_req->operation != BLKIF_OP_READ));
837
838 return rc;
839 }
840
841 static int xen_blkbk_parse_indirect(struct blkif_request *req,
842 struct pending_req *pending_req,
843 struct seg_buf seg[],
844 struct phys_req *preq)
845 {
846 struct grant_page **pages = pending_req->indirect_pages;
847 struct xen_blkif *blkif = pending_req->blkif;
848 int indirect_grefs, rc, n, nseg, i;
849 struct blkif_request_segment *segments = NULL;
850
851 nseg = pending_req->nr_pages;
852 indirect_grefs = INDIRECT_PAGES(nseg);
853 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
854
855 for (i = 0; i < indirect_grefs; i++)
856 pages[i]->gref = req->u.indirect.indirect_grefs[i];
857
858 rc = xen_blkbk_map(blkif, pages, indirect_grefs, true);
859 if (rc)
860 goto unmap;
861
862 for (n = 0, i = 0; n < nseg; n++) {
863 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) {
864 /* Map indirect segments */
865 if (segments)
866 kunmap_atomic(segments);
867 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page);
868 }
869 i = n % SEGS_PER_INDIRECT_FRAME;
870 pending_req->segments[n]->gref = segments[i].gref;
871 seg[n].nsec = segments[i].last_sect -
872 segments[i].first_sect + 1;
873 seg[n].offset = (segments[i].first_sect << 9);
874 if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) ||
875 (segments[i].last_sect < segments[i].first_sect)) {
876 rc = -EINVAL;
877 goto unmap;
878 }
879 preq->nr_sects += seg[n].nsec;
880 }
881
882 unmap:
883 if (segments)
884 kunmap_atomic(segments);
885 xen_blkbk_unmap(blkif, pages, indirect_grefs);
886 return rc;
887 }
888
889 static int dispatch_discard_io(struct xen_blkif *blkif,
890 struct blkif_request *req)
891 {
892 int err = 0;
893 int status = BLKIF_RSP_OKAY;
894 struct block_device *bdev = blkif->vbd.bdev;
895 unsigned long secure;
896 struct phys_req preq;
897
898 xen_blkif_get(blkif);
899
900 preq.sector_number = req->u.discard.sector_number;
901 preq.nr_sects = req->u.discard.nr_sectors;
902
903 err = xen_vbd_translate(&preq, blkif, WRITE);
904 if (err) {
905 pr_warn(DRV_PFX "access denied: DISCARD [%llu->%llu] on dev=%04x\n",
906 preq.sector_number,
907 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
908 goto fail_response;
909 }
910 blkif->st_ds_req++;
911
912 secure = (blkif->vbd.discard_secure &&
913 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
914 BLKDEV_DISCARD_SECURE : 0;
915
916 err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
917 req->u.discard.nr_sectors,
918 GFP_KERNEL, secure);
919 fail_response:
920 if (err == -EOPNOTSUPP) {
921 pr_debug(DRV_PFX "discard op failed, not supported\n");
922 status = BLKIF_RSP_EOPNOTSUPP;
923 } else if (err)
924 status = BLKIF_RSP_ERROR;
925
926 make_response(blkif, req->u.discard.id, req->operation, status);
927 xen_blkif_put(blkif);
928 return err;
929 }
930
931 static int dispatch_other_io(struct xen_blkif *blkif,
932 struct blkif_request *req,
933 struct pending_req *pending_req)
934 {
935 free_req(blkif, pending_req);
936 make_response(blkif, req->u.other.id, req->operation,
937 BLKIF_RSP_EOPNOTSUPP);
938 return -EIO;
939 }
940
941 static void xen_blk_drain_io(struct xen_blkif *blkif)
942 {
943 atomic_set(&blkif->drain, 1);
944 do {
945 if (atomic_read(&blkif->inflight) == 0)
946 break;
947 wait_for_completion_interruptible_timeout(
948 &blkif->drain_complete, HZ);
949
950 if (!atomic_read(&blkif->drain))
951 break;
952 } while (!kthread_should_stop());
953 atomic_set(&blkif->drain, 0);
954 }
955
956 /*
957 * Completion callback on the bio's. Called as bh->b_end_io()
958 */
959
960 static void __end_block_io_op(struct pending_req *pending_req, int error)
961 {
962 /* An error fails the entire request. */
963 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) &&
964 (error == -EOPNOTSUPP)) {
965 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n");
966 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
967 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
968 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
969 (error == -EOPNOTSUPP)) {
970 pr_debug(DRV_PFX "write barrier op failed, not supported\n");
971 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
972 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
973 } else if (error) {
974 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation,"
975 " error=%d\n", error);
976 pending_req->status = BLKIF_RSP_ERROR;
977 }
978
979 /*
980 * If all of the bio's have completed it is time to unmap
981 * the grant references associated with 'request' and provide
982 * the proper response on the ring.
983 */
984 if (atomic_dec_and_test(&pending_req->pendcnt)) {
985 struct xen_blkif *blkif = pending_req->blkif;
986
987 xen_blkbk_unmap(blkif,
988 pending_req->segments,
989 pending_req->nr_pages);
990 make_response(blkif, pending_req->id,
991 pending_req->operation, pending_req->status);
992 free_req(blkif, pending_req);
993 /*
994 * Make sure the request is freed before releasing blkif,
995 * or there could be a race between free_req and the
996 * cleanup done in xen_blkif_free during shutdown.
997 *
998 * NB: The fact that we might try to wake up pending_free_wq
999 * before drain_complete (in case there's a drain going on)
1000 * it's not a problem with our current implementation
1001 * because we can assure there's no thread waiting on
1002 * pending_free_wq if there's a drain going on, but it has
1003 * to be taken into account if the current model is changed.
1004 */
1005 if (atomic_dec_and_test(&blkif->inflight) && atomic_read(&blkif->drain)) {
1006 complete(&blkif->drain_complete);
1007 }
1008 xen_blkif_put(blkif);
1009 }
1010 }
1011
1012 /*
1013 * bio callback.
1014 */
1015 static void end_block_io_op(struct bio *bio, int error)
1016 {
1017 __end_block_io_op(bio->bi_private, error);
1018 bio_put(bio);
1019 }
1020
1021
1022
1023 /*
1024 * Function to copy the from the ring buffer the 'struct blkif_request'
1025 * (which has the sectors we want, number of them, grant references, etc),
1026 * and transmute it to the block API to hand it over to the proper block disk.
1027 */
1028 static int
1029 __do_block_io_op(struct xen_blkif *blkif)
1030 {
1031 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1032 struct blkif_request req;
1033 struct pending_req *pending_req;
1034 RING_IDX rc, rp;
1035 int more_to_do = 0;
1036
1037 rc = blk_rings->common.req_cons;
1038 rp = blk_rings->common.sring->req_prod;
1039 rmb(); /* Ensure we see queued requests up to 'rp'. */
1040
1041 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) {
1042 rc = blk_rings->common.rsp_prod_pvt;
1043 pr_warn(DRV_PFX "Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n",
1044 rp, rc, rp - rc, blkif->vbd.pdevice);
1045 return -EACCES;
1046 }
1047 while (rc != rp) {
1048
1049 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
1050 break;
1051
1052 if (kthread_should_stop()) {
1053 more_to_do = 1;
1054 break;
1055 }
1056
1057 pending_req = alloc_req(blkif);
1058 if (NULL == pending_req) {
1059 blkif->st_oo_req++;
1060 more_to_do = 1;
1061 break;
1062 }
1063
1064 switch (blkif->blk_protocol) {
1065 case BLKIF_PROTOCOL_NATIVE:
1066 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
1067 break;
1068 case BLKIF_PROTOCOL_X86_32:
1069 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
1070 break;
1071 case BLKIF_PROTOCOL_X86_64:
1072 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
1073 break;
1074 default:
1075 BUG();
1076 }
1077 blk_rings->common.req_cons = ++rc; /* before make_response() */
1078
1079 /* Apply all sanity checks to /private copy/ of request. */
1080 barrier();
1081
1082 switch (req.operation) {
1083 case BLKIF_OP_READ:
1084 case BLKIF_OP_WRITE:
1085 case BLKIF_OP_WRITE_BARRIER:
1086 case BLKIF_OP_FLUSH_DISKCACHE:
1087 case BLKIF_OP_INDIRECT:
1088 if (dispatch_rw_block_io(blkif, &req, pending_req))
1089 goto done;
1090 break;
1091 case BLKIF_OP_DISCARD:
1092 free_req(blkif, pending_req);
1093 if (dispatch_discard_io(blkif, &req))
1094 goto done;
1095 break;
1096 default:
1097 if (dispatch_other_io(blkif, &req, pending_req))
1098 goto done;
1099 break;
1100 }
1101
1102 /* Yield point for this unbounded loop. */
1103 cond_resched();
1104 }
1105 done:
1106 return more_to_do;
1107 }
1108
1109 static int
1110 do_block_io_op(struct xen_blkif *blkif)
1111 {
1112 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1113 int more_to_do;
1114
1115 do {
1116 more_to_do = __do_block_io_op(blkif);
1117 if (more_to_do)
1118 break;
1119
1120 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
1121 } while (more_to_do);
1122
1123 return more_to_do;
1124 }
1125 /*
1126 * Transmutation of the 'struct blkif_request' to a proper 'struct bio'
1127 * and call the 'submit_bio' to pass it to the underlying storage.
1128 */
1129 static int dispatch_rw_block_io(struct xen_blkif *blkif,
1130 struct blkif_request *req,
1131 struct pending_req *pending_req)
1132 {
1133 struct phys_req preq;
1134 struct seg_buf *seg = pending_req->seg;
1135 unsigned int nseg;
1136 struct bio *bio = NULL;
1137 struct bio **biolist = pending_req->biolist;
1138 int i, nbio = 0;
1139 int operation;
1140 struct blk_plug plug;
1141 bool drain = false;
1142 struct grant_page **pages = pending_req->segments;
1143 unsigned short req_operation;
1144
1145 req_operation = req->operation == BLKIF_OP_INDIRECT ?
1146 req->u.indirect.indirect_op : req->operation;
1147 if ((req->operation == BLKIF_OP_INDIRECT) &&
1148 (req_operation != BLKIF_OP_READ) &&
1149 (req_operation != BLKIF_OP_WRITE)) {
1150 pr_debug(DRV_PFX "Invalid indirect operation (%u)\n",
1151 req_operation);
1152 goto fail_response;
1153 }
1154
1155 switch (req_operation) {
1156 case BLKIF_OP_READ:
1157 blkif->st_rd_req++;
1158 operation = READ;
1159 break;
1160 case BLKIF_OP_WRITE:
1161 blkif->st_wr_req++;
1162 operation = WRITE_ODIRECT;
1163 break;
1164 case BLKIF_OP_WRITE_BARRIER:
1165 drain = true;
1166 case BLKIF_OP_FLUSH_DISKCACHE:
1167 blkif->st_f_req++;
1168 operation = WRITE_FLUSH;
1169 break;
1170 default:
1171 operation = 0; /* make gcc happy */
1172 goto fail_response;
1173 break;
1174 }
1175
1176 /* Check that the number of segments is sane. */
1177 nseg = req->operation == BLKIF_OP_INDIRECT ?
1178 req->u.indirect.nr_segments : req->u.rw.nr_segments;
1179
1180 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
1181 unlikely((req->operation != BLKIF_OP_INDIRECT) &&
1182 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) ||
1183 unlikely((req->operation == BLKIF_OP_INDIRECT) &&
1184 (nseg > MAX_INDIRECT_SEGMENTS))) {
1185 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
1186 nseg);
1187 /* Haven't submitted any bio's yet. */
1188 goto fail_response;
1189 }
1190
1191 preq.nr_sects = 0;
1192
1193 pending_req->blkif = blkif;
1194 pending_req->id = req->u.rw.id;
1195 pending_req->operation = req_operation;
1196 pending_req->status = BLKIF_RSP_OKAY;
1197 pending_req->nr_pages = nseg;
1198
1199 if (req->operation != BLKIF_OP_INDIRECT) {
1200 preq.dev = req->u.rw.handle;
1201 preq.sector_number = req->u.rw.sector_number;
1202 for (i = 0; i < nseg; i++) {
1203 pages[i]->gref = req->u.rw.seg[i].gref;
1204 seg[i].nsec = req->u.rw.seg[i].last_sect -
1205 req->u.rw.seg[i].first_sect + 1;
1206 seg[i].offset = (req->u.rw.seg[i].first_sect << 9);
1207 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
1208 (req->u.rw.seg[i].last_sect <
1209 req->u.rw.seg[i].first_sect))
1210 goto fail_response;
1211 preq.nr_sects += seg[i].nsec;
1212 }
1213 } else {
1214 preq.dev = req->u.indirect.handle;
1215 preq.sector_number = req->u.indirect.sector_number;
1216 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq))
1217 goto fail_response;
1218 }
1219
1220 if (xen_vbd_translate(&preq, blkif, operation) != 0) {
1221 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n",
1222 operation == READ ? "read" : "write",
1223 preq.sector_number,
1224 preq.sector_number + preq.nr_sects,
1225 blkif->vbd.pdevice);
1226 goto fail_response;
1227 }
1228
1229 /*
1230 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev
1231 * is set there.
1232 */
1233 for (i = 0; i < nseg; i++) {
1234 if (((int)preq.sector_number|(int)seg[i].nsec) &
1235 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
1236 pr_debug(DRV_PFX "Misaligned I/O request from domain %d",
1237 blkif->domid);
1238 goto fail_response;
1239 }
1240 }
1241
1242 /* Wait on all outstanding I/O's and once that has been completed
1243 * issue the WRITE_FLUSH.
1244 */
1245 if (drain)
1246 xen_blk_drain_io(pending_req->blkif);
1247
1248 /*
1249 * If we have failed at this point, we need to undo the M2P override,
1250 * set gnttab_set_unmap_op on all of the grant references and perform
1251 * the hypercall to unmap the grants - that is all done in
1252 * xen_blkbk_unmap.
1253 */
1254 if (xen_blkbk_map_seg(pending_req))
1255 goto fail_flush;
1256
1257 /*
1258 * This corresponding xen_blkif_put is done in __end_block_io_op, or
1259 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
1260 */
1261 xen_blkif_get(blkif);
1262 atomic_inc(&blkif->inflight);
1263
1264 for (i = 0; i < nseg; i++) {
1265 while ((bio == NULL) ||
1266 (bio_add_page(bio,
1267 pages[i]->page,
1268 seg[i].nsec << 9,
1269 seg[i].offset) == 0)) {
1270
1271 int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES);
1272 bio = bio_alloc(GFP_KERNEL, nr_iovecs);
1273 if (unlikely(bio == NULL))
1274 goto fail_put_bio;
1275
1276 biolist[nbio++] = bio;
1277 bio->bi_bdev = preq.bdev;
1278 bio->bi_private = pending_req;
1279 bio->bi_end_io = end_block_io_op;
1280 bio->bi_iter.bi_sector = preq.sector_number;
1281 }
1282
1283 preq.sector_number += seg[i].nsec;
1284 }
1285
1286 /* This will be hit if the operation was a flush or discard. */
1287 if (!bio) {
1288 BUG_ON(operation != WRITE_FLUSH);
1289
1290 bio = bio_alloc(GFP_KERNEL, 0);
1291 if (unlikely(bio == NULL))
1292 goto fail_put_bio;
1293
1294 biolist[nbio++] = bio;
1295 bio->bi_bdev = preq.bdev;
1296 bio->bi_private = pending_req;
1297 bio->bi_end_io = end_block_io_op;
1298 }
1299
1300 atomic_set(&pending_req->pendcnt, nbio);
1301 blk_start_plug(&plug);
1302
1303 for (i = 0; i < nbio; i++)
1304 submit_bio(operation, biolist[i]);
1305
1306 /* Let the I/Os go.. */
1307 blk_finish_plug(&plug);
1308
1309 if (operation == READ)
1310 blkif->st_rd_sect += preq.nr_sects;
1311 else if (operation & WRITE)
1312 blkif->st_wr_sect += preq.nr_sects;
1313
1314 return 0;
1315
1316 fail_flush:
1317 xen_blkbk_unmap(blkif, pending_req->segments,
1318 pending_req->nr_pages);
1319 fail_response:
1320 /* Haven't submitted any bio's yet. */
1321 make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR);
1322 free_req(blkif, pending_req);
1323 msleep(1); /* back off a bit */
1324 return -EIO;
1325
1326 fail_put_bio:
1327 for (i = 0; i < nbio; i++)
1328 bio_put(biolist[i]);
1329 atomic_set(&pending_req->pendcnt, 1);
1330 __end_block_io_op(pending_req, -EINVAL);
1331 msleep(1); /* back off a bit */
1332 return -EIO;
1333 }
1334
1335
1336
1337 /*
1338 * Put a response on the ring on how the operation fared.
1339 */
1340 static void make_response(struct xen_blkif *blkif, u64 id,
1341 unsigned short op, int st)
1342 {
1343 struct blkif_response resp;
1344 unsigned long flags;
1345 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1346 int notify;
1347
1348 resp.id = id;
1349 resp.operation = op;
1350 resp.status = st;
1351
1352 spin_lock_irqsave(&blkif->blk_ring_lock, flags);
1353 /* Place on the response ring for the relevant domain. */
1354 switch (blkif->blk_protocol) {
1355 case BLKIF_PROTOCOL_NATIVE:
1356 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
1357 &resp, sizeof(resp));
1358 break;
1359 case BLKIF_PROTOCOL_X86_32:
1360 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
1361 &resp, sizeof(resp));
1362 break;
1363 case BLKIF_PROTOCOL_X86_64:
1364 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
1365 &resp, sizeof(resp));
1366 break;
1367 default:
1368 BUG();
1369 }
1370 blk_rings->common.rsp_prod_pvt++;
1371 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
1372 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
1373 if (notify)
1374 notify_remote_via_irq(blkif->irq);
1375 }
1376
1377 static int __init xen_blkif_init(void)
1378 {
1379 int rc = 0;
1380
1381 if (!xen_domain())
1382 return -ENODEV;
1383
1384 rc = xen_blkif_interface_init();
1385 if (rc)
1386 goto failed_init;
1387
1388 rc = xen_blkif_xenbus_init();
1389 if (rc)
1390 goto failed_init;
1391
1392 failed_init:
1393 return rc;
1394 }
1395
1396 module_init(xen_blkif_init);
1397
1398 MODULE_LICENSE("Dual BSD/GPL");
1399 MODULE_ALIAS("xen-backend:vbd");
Linux kernel - Deliverables
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