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36
37#define pr_fmt(fmt) "xen-blkback: " fmt
38
39#include <linux/spinlock.h>
40#include <linux/kthread.h>
41#include <linux/list.h>
42#include <linux/delay.h>
43#include <linux/freezer.h>
44#include <linux/bitmap.h>
45
46#include <xen/events.h>
47#include <xen/page.h>
48#include <xen/xen.h>
49#include <asm/xen/hypervisor.h>
50#include <asm/xen/hypercall.h>
51#include <xen/balloon.h>
52#include <xen/grant_table.h>
53#include "common.h"
54
55
56
57
58
59
60
61
62
63
64
65static int max_buffer_pages = 1024;
66module_param_named(max_buffer_pages, max_buffer_pages, int, 0644);
67MODULE_PARM_DESC(max_buffer_pages,
68"Maximum number of free pages to keep in each block backend buffer");
69
70
71
72
73
74
75
76
77
78
79
80
81static int max_pgrants = 1056;
82module_param_named(max_persistent_grants, max_pgrants, int, 0644);
83MODULE_PARM_DESC(max_persistent_grants,
84 "Maximum number of grants to map persistently");
85
86
87
88
89
90
91static unsigned int pgrant_timeout = 60;
92module_param_named(persistent_grant_unused_seconds, pgrant_timeout,
93 uint, 0644);
94MODULE_PARM_DESC(persistent_grant_unused_seconds,
95 "Time in seconds an unused persistent grant is allowed to "
96 "remain allocated. Default is 60, 0 means unlimited.");
97
98
99
100
101
102unsigned int xenblk_max_queues;
103module_param_named(max_queues, xenblk_max_queues, uint, 0644);
104MODULE_PARM_DESC(max_queues,
105 "Maximum number of hardware queues per virtual disk." \
106 "By default it is the number of online CPUs.");
107
108
109
110
111
112unsigned int xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
113module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
114MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
115
116
117
118
119
120#define LRU_INTERVAL 100
121
122
123
124
125
126
127#define LRU_PERCENT_CLEAN 5
128
129
130static unsigned int log_stats;
131module_param(log_stats, int, 0644);
132
133#define BLKBACK_INVALID_HANDLE (~0)
134
135static inline bool persistent_gnt_timeout(struct persistent_gnt *persistent_gnt)
136{
137 return pgrant_timeout && (jiffies - persistent_gnt->last_used >=
138 HZ * pgrant_timeout);
139}
140
141#define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page)))
142
143static int do_block_io_op(struct xen_blkif_ring *ring, unsigned int *eoi_flags);
144static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
145 struct blkif_request *req,
146 struct pending_req *pending_req);
147static void make_response(struct xen_blkif_ring *ring, u64 id,
148 unsigned short op, int st);
149
150#define foreach_grant_safe(pos, n, rbtree, node) \
151 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \
152 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \
153 &(pos)->node != NULL; \
154 (pos) = container_of(n, typeof(*(pos)), node), \
155 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL)
156
157
158
159
160
161
162
163
164
165
166
167
168static int add_persistent_gnt(struct xen_blkif_ring *ring,
169 struct persistent_gnt *persistent_gnt)
170{
171 struct rb_node **new = NULL, *parent = NULL;
172 struct persistent_gnt *this;
173 struct xen_blkif *blkif = ring->blkif;
174
175 if (ring->persistent_gnt_c >= max_pgrants) {
176 if (!blkif->vbd.overflow_max_grants)
177 blkif->vbd.overflow_max_grants = 1;
178 return -EBUSY;
179 }
180
181 new = &ring->persistent_gnts.rb_node;
182 while (*new) {
183 this = container_of(*new, struct persistent_gnt, node);
184
185 parent = *new;
186 if (persistent_gnt->gnt < this->gnt)
187 new = &((*new)->rb_left);
188 else if (persistent_gnt->gnt > this->gnt)
189 new = &((*new)->rb_right);
190 else {
191 pr_alert_ratelimited("trying to add a gref that's already in the tree\n");
192 return -EINVAL;
193 }
194 }
195
196 persistent_gnt->active = true;
197
198 rb_link_node(&(persistent_gnt->node), parent, new);
199 rb_insert_color(&(persistent_gnt->node), &ring->persistent_gnts);
200 ring->persistent_gnt_c++;
201 atomic_inc(&ring->persistent_gnt_in_use);
202 return 0;
203}
204
205static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring,
206 grant_ref_t gref)
207{
208 struct persistent_gnt *data;
209 struct rb_node *node = NULL;
210
211 node = ring->persistent_gnts.rb_node;
212 while (node) {
213 data = container_of(node, struct persistent_gnt, node);
214
215 if (gref < data->gnt)
216 node = node->rb_left;
217 else if (gref > data->gnt)
218 node = node->rb_right;
219 else {
220 if (data->active) {
221 pr_alert_ratelimited("requesting a grant already in use\n");
222 return NULL;
223 }
224 data->active = true;
225 atomic_inc(&ring->persistent_gnt_in_use);
226 return data;
227 }
228 }
229 return NULL;
230}
231
232static void put_persistent_gnt(struct xen_blkif_ring *ring,
233 struct persistent_gnt *persistent_gnt)
234{
235 if (!persistent_gnt->active)
236 pr_alert_ratelimited("freeing a grant already unused\n");
237 persistent_gnt->last_used = jiffies;
238 persistent_gnt->active = false;
239 atomic_dec(&ring->persistent_gnt_in_use);
240}
241
242static void free_persistent_gnts(struct xen_blkif_ring *ring, struct rb_root *root,
243 unsigned int num)
244{
245 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
246 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
247 struct persistent_gnt *persistent_gnt;
248 struct rb_node *n;
249 int segs_to_unmap = 0;
250 struct gntab_unmap_queue_data unmap_data;
251
252 unmap_data.pages = pages;
253 unmap_data.unmap_ops = unmap;
254 unmap_data.kunmap_ops = NULL;
255
256 foreach_grant_safe(persistent_gnt, n, root, node) {
257 BUG_ON(persistent_gnt->handle ==
258 BLKBACK_INVALID_HANDLE);
259 gnttab_set_unmap_op(&unmap[segs_to_unmap],
260 (unsigned long) pfn_to_kaddr(page_to_pfn(
261 persistent_gnt->page)),
262 GNTMAP_host_map,
263 persistent_gnt->handle);
264
265 pages[segs_to_unmap] = persistent_gnt->page;
266
267 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
268 !rb_next(&persistent_gnt->node)) {
269
270 unmap_data.count = segs_to_unmap;
271 BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
272
273 gnttab_page_cache_put(&ring->free_pages, pages,
274 segs_to_unmap);
275 segs_to_unmap = 0;
276 }
277
278 rb_erase(&persistent_gnt->node, root);
279 kfree(persistent_gnt);
280 num--;
281 }
282 BUG_ON(num != 0);
283}
284
285void xen_blkbk_unmap_purged_grants(struct work_struct *work)
286{
287 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
288 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
289 struct persistent_gnt *persistent_gnt;
290 int segs_to_unmap = 0;
291 struct xen_blkif_ring *ring = container_of(work, typeof(*ring), persistent_purge_work);
292 struct gntab_unmap_queue_data unmap_data;
293
294 unmap_data.pages = pages;
295 unmap_data.unmap_ops = unmap;
296 unmap_data.kunmap_ops = NULL;
297
298 while(!list_empty(&ring->persistent_purge_list)) {
299 persistent_gnt = list_first_entry(&ring->persistent_purge_list,
300 struct persistent_gnt,
301 remove_node);
302 list_del(&persistent_gnt->remove_node);
303
304 gnttab_set_unmap_op(&unmap[segs_to_unmap],
305 vaddr(persistent_gnt->page),
306 GNTMAP_host_map,
307 persistent_gnt->handle);
308
309 pages[segs_to_unmap] = persistent_gnt->page;
310
311 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
312 unmap_data.count = segs_to_unmap;
313 BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
314 gnttab_page_cache_put(&ring->free_pages, pages,
315 segs_to_unmap);
316 segs_to_unmap = 0;
317 }
318 kfree(persistent_gnt);
319 }
320 if (segs_to_unmap > 0) {
321 unmap_data.count = segs_to_unmap;
322 BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
323 gnttab_page_cache_put(&ring->free_pages, pages, segs_to_unmap);
324 }
325}
326
327static void purge_persistent_gnt(struct xen_blkif_ring *ring)
328{
329 struct persistent_gnt *persistent_gnt;
330 struct rb_node *n;
331 unsigned int num_clean, total;
332 bool scan_used = false;
333 struct rb_root *root;
334
335 if (work_busy(&ring->persistent_purge_work)) {
336 pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n");
337 goto out;
338 }
339
340 if (ring->persistent_gnt_c < max_pgrants ||
341 (ring->persistent_gnt_c == max_pgrants &&
342 !ring->blkif->vbd.overflow_max_grants)) {
343 num_clean = 0;
344 } else {
345 num_clean = (max_pgrants / 100) * LRU_PERCENT_CLEAN;
346 num_clean = ring->persistent_gnt_c - max_pgrants + num_clean;
347 num_clean = min(ring->persistent_gnt_c, num_clean);
348 pr_debug("Going to purge at least %u persistent grants\n",
349 num_clean);
350 }
351
352
353
354
355
356
357
358
359
360
361 total = 0;
362
363 BUG_ON(!list_empty(&ring->persistent_purge_list));
364 root = &ring->persistent_gnts;
365purge_list:
366 foreach_grant_safe(persistent_gnt, n, root, node) {
367 BUG_ON(persistent_gnt->handle ==
368 BLKBACK_INVALID_HANDLE);
369
370 if (persistent_gnt->active)
371 continue;
372 if (!scan_used && !persistent_gnt_timeout(persistent_gnt))
373 continue;
374 if (scan_used && total >= num_clean)
375 continue;
376
377 rb_erase(&persistent_gnt->node, root);
378 list_add(&persistent_gnt->remove_node,
379 &ring->persistent_purge_list);
380 total++;
381 }
382
383
384
385
386
387 if (!scan_used && total < num_clean) {
388 pr_debug("Still missing %u purged frames\n", num_clean - total);
389 scan_used = true;
390 goto purge_list;
391 }
392
393 if (total) {
394 ring->persistent_gnt_c -= total;
395 ring->blkif->vbd.overflow_max_grants = 0;
396
397
398 schedule_work(&ring->persistent_purge_work);
399 pr_debug("Purged %u/%u\n", num_clean, total);
400 }
401
402out:
403 return;
404}
405
406
407
408
409static struct pending_req *alloc_req(struct xen_blkif_ring *ring)
410{
411 struct pending_req *req = NULL;
412 unsigned long flags;
413
414 spin_lock_irqsave(&ring->pending_free_lock, flags);
415 if (!list_empty(&ring->pending_free)) {
416 req = list_entry(ring->pending_free.next, struct pending_req,
417 free_list);
418 list_del(&req->free_list);
419 }
420 spin_unlock_irqrestore(&ring->pending_free_lock, flags);
421 return req;
422}
423
424
425
426
427
428static void free_req(struct xen_blkif_ring *ring, struct pending_req *req)
429{
430 unsigned long flags;
431 int was_empty;
432
433 spin_lock_irqsave(&ring->pending_free_lock, flags);
434 was_empty = list_empty(&ring->pending_free);
435 list_add(&req->free_list, &ring->pending_free);
436 spin_unlock_irqrestore(&ring->pending_free_lock, flags);
437 if (was_empty)
438 wake_up(&ring->pending_free_wq);
439}
440
441
442
443
444static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
445 int operation)
446{
447 struct xen_vbd *vbd = &blkif->vbd;
448 int rc = -EACCES;
449
450 if ((operation != REQ_OP_READ) && vbd->readonly)
451 goto out;
452
453 if (likely(req->nr_sects)) {
454 blkif_sector_t end = req->sector_number + req->nr_sects;
455
456 if (unlikely(end < req->sector_number))
457 goto out;
458 if (unlikely(end > vbd_sz(vbd)))
459 goto out;
460 }
461
462 req->dev = vbd->pdevice;
463 req->bdev = vbd->bdev;
464 rc = 0;
465
466 out:
467 return rc;
468}
469
470static void xen_vbd_resize(struct xen_blkif *blkif)
471{
472 struct xen_vbd *vbd = &blkif->vbd;
473 struct xenbus_transaction xbt;
474 int err;
475 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be);
476 unsigned long long new_size = vbd_sz(vbd);
477
478 pr_info("VBD Resize: Domid: %d, Device: (%d, %d)\n",
479 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
480 pr_info("VBD Resize: new size %llu\n", new_size);
481 vbd->size = new_size;
482again:
483 err = xenbus_transaction_start(&xbt);
484 if (err) {
485 pr_warn("Error starting transaction\n");
486 return;
487 }
488 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
489 (unsigned long long)vbd_sz(vbd));
490 if (err) {
491 pr_warn("Error writing new size\n");
492 goto abort;
493 }
494
495
496
497
498
499 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
500 if (err) {
501 pr_warn("Error writing the state\n");
502 goto abort;
503 }
504
505 err = xenbus_transaction_end(xbt, 0);
506 if (err == -EAGAIN)
507 goto again;
508 if (err)
509 pr_warn("Error ending transaction\n");
510 return;
511abort:
512 xenbus_transaction_end(xbt, 1);
513}
514
515
516
517
518static void blkif_notify_work(struct xen_blkif_ring *ring)
519{
520 ring->waiting_reqs = 1;
521 wake_up(&ring->wq);
522}
523
524irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
525{
526 blkif_notify_work(dev_id);
527 return IRQ_HANDLED;
528}
529
530
531
532
533
534static void print_stats(struct xen_blkif_ring *ring)
535{
536 pr_info("(%s): oo %3llu | rd %4llu | wr %4llu | f %4llu"
537 " | ds %4llu | pg: %4u/%4d\n",
538 current->comm, ring->st_oo_req,
539 ring->st_rd_req, ring->st_wr_req,
540 ring->st_f_req, ring->st_ds_req,
541 ring->persistent_gnt_c, max_pgrants);
542 ring->st_print = jiffies + msecs_to_jiffies(10 * 1000);
543 ring->st_rd_req = 0;
544 ring->st_wr_req = 0;
545 ring->st_oo_req = 0;
546 ring->st_ds_req = 0;
547}
548
549int xen_blkif_schedule(void *arg)
550{
551 struct xen_blkif_ring *ring = arg;
552 struct xen_blkif *blkif = ring->blkif;
553 struct xen_vbd *vbd = &blkif->vbd;
554 unsigned long timeout;
555 int ret;
556 bool do_eoi;
557 unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
558
559 set_freezable();
560 while (!kthread_should_stop()) {
561 if (try_to_freeze())
562 continue;
563 if (unlikely(vbd->size != vbd_sz(vbd)))
564 xen_vbd_resize(blkif);
565
566 timeout = msecs_to_jiffies(LRU_INTERVAL);
567
568 timeout = wait_event_interruptible_timeout(
569 ring->wq,
570 ring->waiting_reqs || kthread_should_stop(),
571 timeout);
572 if (timeout == 0)
573 goto purge_gnt_list;
574 timeout = wait_event_interruptible_timeout(
575 ring->pending_free_wq,
576 !list_empty(&ring->pending_free) ||
577 kthread_should_stop(),
578 timeout);
579 if (timeout == 0)
580 goto purge_gnt_list;
581
582 do_eoi = ring->waiting_reqs;
583
584 ring->waiting_reqs = 0;
585 smp_mb();
586
587 ret = do_block_io_op(ring, &eoi_flags);
588 if (ret > 0)
589 ring->waiting_reqs = 1;
590 if (ret == -EACCES)
591 wait_event_interruptible(ring->shutdown_wq,
592 kthread_should_stop());
593
594 if (do_eoi && !ring->waiting_reqs) {
595 xen_irq_lateeoi(ring->irq, eoi_flags);
596 eoi_flags |= XEN_EOI_FLAG_SPURIOUS;
597 }
598
599purge_gnt_list:
600 if (blkif->vbd.feature_gnt_persistent &&
601 time_after(jiffies, ring->next_lru)) {
602 purge_persistent_gnt(ring);
603 ring->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL);
604 }
605
606
607 if (time_before(jiffies, blkif->buffer_squeeze_end))
608 gnttab_page_cache_shrink(&ring->free_pages, 0);
609 else
610 gnttab_page_cache_shrink(&ring->free_pages,
611 max_buffer_pages);
612
613 if (log_stats && time_after(jiffies, ring->st_print))
614 print_stats(ring);
615 }
616
617
618 flush_work(&ring->persistent_purge_work);
619
620 if (log_stats)
621 print_stats(ring);
622
623 ring->xenblkd = NULL;
624
625 return 0;
626}
627
628
629
630
631void xen_blkbk_free_caches(struct xen_blkif_ring *ring)
632{
633
634 if (!RB_EMPTY_ROOT(&ring->persistent_gnts))
635 free_persistent_gnts(ring, &ring->persistent_gnts,
636 ring->persistent_gnt_c);
637
638 BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
639 ring->persistent_gnt_c = 0;
640
641
642 gnttab_page_cache_shrink(&ring->free_pages, 0 );
643}
644
645static unsigned int xen_blkbk_unmap_prepare(
646 struct xen_blkif_ring *ring,
647 struct grant_page **pages,
648 unsigned int num,
649 struct gnttab_unmap_grant_ref *unmap_ops,
650 struct page **unmap_pages)
651{
652 unsigned int i, invcount = 0;
653
654 for (i = 0; i < num; i++) {
655 if (pages[i]->persistent_gnt != NULL) {
656 put_persistent_gnt(ring, pages[i]->persistent_gnt);
657 continue;
658 }
659 if (pages[i]->handle == BLKBACK_INVALID_HANDLE)
660 continue;
661 unmap_pages[invcount] = pages[i]->page;
662 gnttab_set_unmap_op(&unmap_ops[invcount], vaddr(pages[i]->page),
663 GNTMAP_host_map, pages[i]->handle);
664 pages[i]->handle = BLKBACK_INVALID_HANDLE;
665 invcount++;
666 }
667
668 return invcount;
669}
670
671static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_queue_data *data)
672{
673 struct pending_req *pending_req = (struct pending_req *)(data->data);
674 struct xen_blkif_ring *ring = pending_req->ring;
675 struct xen_blkif *blkif = ring->blkif;
676
677
678
679 BUG_ON(result);
680
681 gnttab_page_cache_put(&ring->free_pages, data->pages, data->count);
682 make_response(ring, pending_req->id,
683 pending_req->operation, pending_req->status);
684 free_req(ring, pending_req);
685
686
687
688
689
690
691
692
693
694
695
696
697 if (atomic_dec_and_test(&ring->inflight) && atomic_read(&blkif->drain)) {
698 complete(&blkif->drain_complete);
699 }
700 xen_blkif_put(blkif);
701}
702
703static void xen_blkbk_unmap_and_respond(struct pending_req *req)
704{
705 struct gntab_unmap_queue_data* work = &req->gnttab_unmap_data;
706 struct xen_blkif_ring *ring = req->ring;
707 struct grant_page **pages = req->segments;
708 unsigned int invcount;
709
710 invcount = xen_blkbk_unmap_prepare(ring, pages, req->nr_segs,
711 req->unmap, req->unmap_pages);
712
713 work->data = req;
714 work->done = xen_blkbk_unmap_and_respond_callback;
715 work->unmap_ops = req->unmap;
716 work->kunmap_ops = NULL;
717 work->pages = req->unmap_pages;
718 work->count = invcount;
719
720 gnttab_unmap_refs_async(&req->gnttab_unmap_data);
721}
722
723
724
725
726
727
728
729
730
731static void xen_blkbk_unmap(struct xen_blkif_ring *ring,
732 struct grant_page *pages[],
733 int num)
734{
735 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
736 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
737 unsigned int invcount = 0;
738 int ret;
739
740 while (num) {
741 unsigned int batch = min(num, BLKIF_MAX_SEGMENTS_PER_REQUEST);
742
743 invcount = xen_blkbk_unmap_prepare(ring, pages, batch,
744 unmap, unmap_pages);
745 if (invcount) {
746 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
747 BUG_ON(ret);
748 gnttab_page_cache_put(&ring->free_pages, unmap_pages,
749 invcount);
750 }
751 pages += batch;
752 num -= batch;
753 }
754}
755
756static int xen_blkbk_map(struct xen_blkif_ring *ring,
757 struct grant_page *pages[],
758 int num, bool ro)
759{
760 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
761 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
762 struct persistent_gnt *persistent_gnt = NULL;
763 phys_addr_t addr = 0;
764 int i, seg_idx, new_map_idx;
765 int segs_to_map = 0;
766 int ret = 0;
767 int last_map = 0, map_until = 0;
768 int use_persistent_gnts;
769 struct xen_blkif *blkif = ring->blkif;
770
771 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
772
773
774
775
776
777
778again:
779 for (i = map_until; i < num; i++) {
780 uint32_t flags;
781
782 if (use_persistent_gnts) {
783 persistent_gnt = get_persistent_gnt(
784 ring,
785 pages[i]->gref);
786 }
787
788 if (persistent_gnt) {
789
790
791
792
793 pages[i]->page = persistent_gnt->page;
794 pages[i]->persistent_gnt = persistent_gnt;
795 } else {
796 if (gnttab_page_cache_get(&ring->free_pages,
797 &pages[i]->page)) {
798 gnttab_page_cache_put(&ring->free_pages,
799 pages_to_gnt,
800 segs_to_map);
801 ret = -ENOMEM;
802 goto out;
803 }
804 addr = vaddr(pages[i]->page);
805 pages_to_gnt[segs_to_map] = pages[i]->page;
806 pages[i]->persistent_gnt = NULL;
807 flags = GNTMAP_host_map;
808 if (!use_persistent_gnts && ro)
809 flags |= GNTMAP_readonly;
810 gnttab_set_map_op(&map[segs_to_map++], addr,
811 flags, pages[i]->gref,
812 blkif->domid);
813 }
814 map_until = i + 1;
815 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST)
816 break;
817 }
818
819 if (segs_to_map)
820 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
821
822
823
824
825
826
827 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) {
828 if (!pages[seg_idx]->persistent_gnt) {
829
830 BUG_ON(new_map_idx >= segs_to_map);
831 if (unlikely(map[new_map_idx].status != 0)) {
832 pr_debug("invalid buffer -- could not remap it\n");
833 gnttab_page_cache_put(&ring->free_pages,
834 &pages[seg_idx]->page, 1);
835 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE;
836 ret |= !ret;
837 goto next;
838 }
839 pages[seg_idx]->handle = map[new_map_idx].handle;
840 } else {
841 continue;
842 }
843 if (use_persistent_gnts &&
844 ring->persistent_gnt_c < max_pgrants) {
845
846
847
848
849 persistent_gnt = kmalloc(sizeof(struct persistent_gnt),
850 GFP_KERNEL);
851 if (!persistent_gnt) {
852
853
854
855
856
857 goto next;
858 }
859 persistent_gnt->gnt = map[new_map_idx].ref;
860 persistent_gnt->handle = map[new_map_idx].handle;
861 persistent_gnt->page = pages[seg_idx]->page;
862 if (add_persistent_gnt(ring,
863 persistent_gnt)) {
864 kfree(persistent_gnt);
865 persistent_gnt = NULL;
866 goto next;
867 }
868 pages[seg_idx]->persistent_gnt = persistent_gnt;
869 pr_debug("grant %u added to the tree of persistent grants, using %u/%u\n",
870 persistent_gnt->gnt, ring->persistent_gnt_c,
871 max_pgrants);
872 goto next;
873 }
874 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) {
875 blkif->vbd.overflow_max_grants = 1;
876 pr_debug("domain %u, device %#x is using maximum number of persistent grants\n",
877 blkif->domid, blkif->vbd.handle);
878 }
879
880
881
882
883next:
884 new_map_idx++;
885 }
886 segs_to_map = 0;
887 last_map = map_until;
888 if (!ret && map_until != num)
889 goto again;
890
891out:
892 for (i = last_map; i < num; i++) {
893
894 if(i >= map_until)
895 pages[i]->persistent_gnt = NULL;
896 pages[i]->handle = BLKBACK_INVALID_HANDLE;
897 }
898
899 return ret;
900}
901
902static int xen_blkbk_map_seg(struct pending_req *pending_req)
903{
904 int rc;
905
906 rc = xen_blkbk_map(pending_req->ring, pending_req->segments,
907 pending_req->nr_segs,
908 (pending_req->operation != BLKIF_OP_READ));
909
910 return rc;
911}
912
913static int xen_blkbk_parse_indirect(struct blkif_request *req,
914 struct pending_req *pending_req,
915 struct seg_buf seg[],
916 struct phys_req *preq)
917{
918 struct grant_page **pages = pending_req->indirect_pages;
919 struct xen_blkif_ring *ring = pending_req->ring;
920 int indirect_grefs, rc, n, nseg, i;
921 struct blkif_request_segment *segments = NULL;
922
923 nseg = pending_req->nr_segs;
924 indirect_grefs = INDIRECT_PAGES(nseg);
925 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
926
927 for (i = 0; i < indirect_grefs; i++)
928 pages[i]->gref = req->u.indirect.indirect_grefs[i];
929
930 rc = xen_blkbk_map(ring, pages, indirect_grefs, true);
931 if (rc)
932 goto unmap;
933
934 for (n = 0, i = 0; n < nseg; n++) {
935 uint8_t first_sect, last_sect;
936
937 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) {
938
939 if (segments)
940 kunmap_atomic(segments);
941 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page);
942 }
943 i = n % SEGS_PER_INDIRECT_FRAME;
944
945 pending_req->segments[n]->gref = segments[i].gref;
946
947 first_sect = READ_ONCE(segments[i].first_sect);
948 last_sect = READ_ONCE(segments[i].last_sect);
949 if (last_sect >= (XEN_PAGE_SIZE >> 9) || last_sect < first_sect) {
950 rc = -EINVAL;
951 goto unmap;
952 }
953
954 seg[n].nsec = last_sect - first_sect + 1;
955 seg[n].offset = first_sect << 9;
956 preq->nr_sects += seg[n].nsec;
957 }
958
959unmap:
960 if (segments)
961 kunmap_atomic(segments);
962 xen_blkbk_unmap(ring, pages, indirect_grefs);
963 return rc;
964}
965
966static int dispatch_discard_io(struct xen_blkif_ring *ring,
967 struct blkif_request *req)
968{
969 int err = 0;
970 int status = BLKIF_RSP_OKAY;
971 struct xen_blkif *blkif = ring->blkif;
972 struct block_device *bdev = blkif->vbd.bdev;
973 unsigned long secure;
974 struct phys_req preq;
975
976 xen_blkif_get(blkif);
977
978 preq.sector_number = req->u.discard.sector_number;
979 preq.nr_sects = req->u.discard.nr_sectors;
980
981 err = xen_vbd_translate(&preq, blkif, REQ_OP_WRITE);
982 if (err) {
983 pr_warn("access denied: DISCARD [%llu->%llu] on dev=%04x\n",
984 preq.sector_number,
985 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
986 goto fail_response;
987 }
988 ring->st_ds_req++;
989
990 secure = (blkif->vbd.discard_secure &&
991 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
992 BLKDEV_DISCARD_SECURE : 0;
993
994 err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
995 req->u.discard.nr_sectors,
996 GFP_KERNEL, secure);
997fail_response:
998 if (err == -EOPNOTSUPP) {
999 pr_debug("discard op failed, not supported\n");
1000 status = BLKIF_RSP_EOPNOTSUPP;
1001 } else if (err)
1002 status = BLKIF_RSP_ERROR;
1003
1004 make_response(ring, req->u.discard.id, req->operation, status);
1005 xen_blkif_put(blkif);
1006 return err;
1007}
1008
1009static int dispatch_other_io(struct xen_blkif_ring *ring,
1010 struct blkif_request *req,
1011 struct pending_req *pending_req)
1012{
1013 free_req(ring, pending_req);
1014 make_response(ring, req->u.other.id, req->operation,
1015 BLKIF_RSP_EOPNOTSUPP);
1016 return -EIO;
1017}
1018
1019static void xen_blk_drain_io(struct xen_blkif_ring *ring)
1020{
1021 struct xen_blkif *blkif = ring->blkif;
1022
1023 atomic_set(&blkif->drain, 1);
1024 do {
1025 if (atomic_read(&ring->inflight) == 0)
1026 break;
1027 wait_for_completion_interruptible_timeout(
1028 &blkif->drain_complete, HZ);
1029
1030 if (!atomic_read(&blkif->drain))
1031 break;
1032 } while (!kthread_should_stop());
1033 atomic_set(&blkif->drain, 0);
1034}
1035
1036static void __end_block_io_op(struct pending_req *pending_req,
1037 blk_status_t error)
1038{
1039
1040 if (pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE &&
1041 error == BLK_STS_NOTSUPP) {
1042 pr_debug("flush diskcache op failed, not supported\n");
1043 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->ring->blkif->be, 0);
1044 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
1045 } else if (pending_req->operation == BLKIF_OP_WRITE_BARRIER &&
1046 error == BLK_STS_NOTSUPP) {
1047 pr_debug("write barrier op failed, not supported\n");
1048 xen_blkbk_barrier(XBT_NIL, pending_req->ring->blkif->be, 0);
1049 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
1050 } else if (error) {
1051 pr_debug("Buffer not up-to-date at end of operation,"
1052 " error=%d\n", error);
1053 pending_req->status = BLKIF_RSP_ERROR;
1054 }
1055
1056
1057
1058
1059
1060
1061 if (atomic_dec_and_test(&pending_req->pendcnt))
1062 xen_blkbk_unmap_and_respond(pending_req);
1063}
1064
1065
1066
1067
1068static void end_block_io_op(struct bio *bio)
1069{
1070 __end_block_io_op(bio->bi_private, bio->bi_status);
1071 bio_put(bio);
1072}
1073
1074
1075
1076
1077
1078
1079
1080
1081static int
1082__do_block_io_op(struct xen_blkif_ring *ring, unsigned int *eoi_flags)
1083{
1084 union blkif_back_rings *blk_rings = &ring->blk_rings;
1085 struct blkif_request req;
1086 struct pending_req *pending_req;
1087 RING_IDX rc, rp;
1088 int more_to_do = 0;
1089
1090 rc = blk_rings->common.req_cons;
1091 rp = blk_rings->common.sring->req_prod;
1092 rmb();
1093
1094 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) {
1095 rc = blk_rings->common.rsp_prod_pvt;
1096 pr_warn("Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n",
1097 rp, rc, rp - rc, ring->blkif->vbd.pdevice);
1098 return -EACCES;
1099 }
1100 while (rc != rp) {
1101
1102 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
1103 break;
1104
1105
1106 *eoi_flags &= ~XEN_EOI_FLAG_SPURIOUS;
1107
1108 if (kthread_should_stop()) {
1109 more_to_do = 1;
1110 break;
1111 }
1112
1113 pending_req = alloc_req(ring);
1114 if (NULL == pending_req) {
1115 ring->st_oo_req++;
1116 more_to_do = 1;
1117 break;
1118 }
1119
1120 switch (ring->blkif->blk_protocol) {
1121 case BLKIF_PROTOCOL_NATIVE:
1122 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
1123 break;
1124 case BLKIF_PROTOCOL_X86_32:
1125 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
1126 break;
1127 case BLKIF_PROTOCOL_X86_64:
1128 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
1129 break;
1130 default:
1131 BUG();
1132 }
1133 blk_rings->common.req_cons = ++rc;
1134
1135
1136 barrier();
1137
1138 switch (req.operation) {
1139 case BLKIF_OP_READ:
1140 case BLKIF_OP_WRITE:
1141 case BLKIF_OP_WRITE_BARRIER:
1142 case BLKIF_OP_FLUSH_DISKCACHE:
1143 case BLKIF_OP_INDIRECT:
1144 if (dispatch_rw_block_io(ring, &req, pending_req))
1145 goto done;
1146 break;
1147 case BLKIF_OP_DISCARD:
1148 free_req(ring, pending_req);
1149 if (dispatch_discard_io(ring, &req))
1150 goto done;
1151 break;
1152 default:
1153 if (dispatch_other_io(ring, &req, pending_req))
1154 goto done;
1155 break;
1156 }
1157
1158
1159 cond_resched();
1160 }
1161done:
1162 return more_to_do;
1163}
1164
1165static int
1166do_block_io_op(struct xen_blkif_ring *ring, unsigned int *eoi_flags)
1167{
1168 union blkif_back_rings *blk_rings = &ring->blk_rings;
1169 int more_to_do;
1170
1171 do {
1172 more_to_do = __do_block_io_op(ring, eoi_flags);
1173 if (more_to_do)
1174 break;
1175
1176 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
1177 } while (more_to_do);
1178
1179 return more_to_do;
1180}
1181
1182
1183
1184
1185static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
1186 struct blkif_request *req,
1187 struct pending_req *pending_req)
1188{
1189 struct phys_req preq;
1190 struct seg_buf *seg = pending_req->seg;
1191 unsigned int nseg;
1192 struct bio *bio = NULL;
1193 struct bio **biolist = pending_req->biolist;
1194 int i, nbio = 0;
1195 int operation;
1196 int operation_flags = 0;
1197 struct blk_plug plug;
1198 bool drain = false;
1199 struct grant_page **pages = pending_req->segments;
1200 unsigned short req_operation;
1201
1202 req_operation = req->operation == BLKIF_OP_INDIRECT ?
1203 req->u.indirect.indirect_op : req->operation;
1204
1205 if ((req->operation == BLKIF_OP_INDIRECT) &&
1206 (req_operation != BLKIF_OP_READ) &&
1207 (req_operation != BLKIF_OP_WRITE)) {
1208 pr_debug("Invalid indirect operation (%u)\n", req_operation);
1209 goto fail_response;
1210 }
1211
1212 switch (req_operation) {
1213 case BLKIF_OP_READ:
1214 ring->st_rd_req++;
1215 operation = REQ_OP_READ;
1216 break;
1217 case BLKIF_OP_WRITE:
1218 ring->st_wr_req++;
1219 operation = REQ_OP_WRITE;
1220 operation_flags = REQ_SYNC | REQ_IDLE;
1221 break;
1222 case BLKIF_OP_WRITE_BARRIER:
1223 drain = true;
1224 fallthrough;
1225 case BLKIF_OP_FLUSH_DISKCACHE:
1226 ring->st_f_req++;
1227 operation = REQ_OP_WRITE;
1228 operation_flags = REQ_PREFLUSH;
1229 break;
1230 default:
1231 operation = 0;
1232 goto fail_response;
1233 break;
1234 }
1235
1236
1237 nseg = req->operation == BLKIF_OP_INDIRECT ?
1238 req->u.indirect.nr_segments : req->u.rw.nr_segments;
1239
1240 if (unlikely(nseg == 0 && operation_flags != REQ_PREFLUSH) ||
1241 unlikely((req->operation != BLKIF_OP_INDIRECT) &&
1242 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) ||
1243 unlikely((req->operation == BLKIF_OP_INDIRECT) &&
1244 (nseg > MAX_INDIRECT_SEGMENTS))) {
1245 pr_debug("Bad number of segments in request (%d)\n", nseg);
1246
1247 goto fail_response;
1248 }
1249
1250 preq.nr_sects = 0;
1251
1252 pending_req->ring = ring;
1253 pending_req->id = req->u.rw.id;
1254 pending_req->operation = req_operation;
1255 pending_req->status = BLKIF_RSP_OKAY;
1256 pending_req->nr_segs = nseg;
1257
1258 if (req->operation != BLKIF_OP_INDIRECT) {
1259 preq.dev = req->u.rw.handle;
1260 preq.sector_number = req->u.rw.sector_number;
1261 for (i = 0; i < nseg; i++) {
1262 pages[i]->gref = req->u.rw.seg[i].gref;
1263 seg[i].nsec = req->u.rw.seg[i].last_sect -
1264 req->u.rw.seg[i].first_sect + 1;
1265 seg[i].offset = (req->u.rw.seg[i].first_sect << 9);
1266 if ((req->u.rw.seg[i].last_sect >= (XEN_PAGE_SIZE >> 9)) ||
1267 (req->u.rw.seg[i].last_sect <
1268 req->u.rw.seg[i].first_sect))
1269 goto fail_response;
1270 preq.nr_sects += seg[i].nsec;
1271 }
1272 } else {
1273 preq.dev = req->u.indirect.handle;
1274 preq.sector_number = req->u.indirect.sector_number;
1275 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq))
1276 goto fail_response;
1277 }
1278
1279 if (xen_vbd_translate(&preq, ring->blkif, operation) != 0) {
1280 pr_debug("access denied: %s of [%llu,%llu] on dev=%04x\n",
1281 operation == REQ_OP_READ ? "read" : "write",
1282 preq.sector_number,
1283 preq.sector_number + preq.nr_sects,
1284 ring->blkif->vbd.pdevice);
1285 goto fail_response;
1286 }
1287
1288
1289
1290
1291
1292 for (i = 0; i < nseg; i++) {
1293 if (((int)preq.sector_number|(int)seg[i].nsec) &
1294 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
1295 pr_debug("Misaligned I/O request from domain %d\n",
1296 ring->blkif->domid);
1297 goto fail_response;
1298 }
1299 }
1300
1301
1302
1303
1304 if (drain)
1305 xen_blk_drain_io(pending_req->ring);
1306
1307
1308
1309
1310
1311
1312
1313 if (xen_blkbk_map_seg(pending_req))
1314 goto fail_flush;
1315
1316
1317
1318
1319
1320 xen_blkif_get(ring->blkif);
1321 atomic_inc(&ring->inflight);
1322
1323 for (i = 0; i < nseg; i++) {
1324 while ((bio == NULL) ||
1325 (bio_add_page(bio,
1326 pages[i]->page,
1327 seg[i].nsec << 9,
1328 seg[i].offset) == 0)) {
1329 bio = bio_alloc(GFP_KERNEL, bio_max_segs(nseg - i));
1330 if (unlikely(bio == NULL))
1331 goto fail_put_bio;
1332
1333 biolist[nbio++] = bio;
1334 bio_set_dev(bio, preq.bdev);
1335 bio->bi_private = pending_req;
1336 bio->bi_end_io = end_block_io_op;
1337 bio->bi_iter.bi_sector = preq.sector_number;
1338 bio_set_op_attrs(bio, operation, operation_flags);
1339 }
1340
1341 preq.sector_number += seg[i].nsec;
1342 }
1343
1344
1345 if (!bio) {
1346 BUG_ON(operation_flags != REQ_PREFLUSH);
1347
1348 bio = bio_alloc(GFP_KERNEL, 0);
1349 if (unlikely(bio == NULL))
1350 goto fail_put_bio;
1351
1352 biolist[nbio++] = bio;
1353 bio_set_dev(bio, preq.bdev);
1354 bio->bi_private = pending_req;
1355 bio->bi_end_io = end_block_io_op;
1356 bio_set_op_attrs(bio, operation, operation_flags);
1357 }
1358
1359 atomic_set(&pending_req->pendcnt, nbio);
1360 blk_start_plug(&plug);
1361
1362 for (i = 0; i < nbio; i++)
1363 submit_bio(biolist[i]);
1364
1365
1366 blk_finish_plug(&plug);
1367
1368 if (operation == REQ_OP_READ)
1369 ring->st_rd_sect += preq.nr_sects;
1370 else if (operation == REQ_OP_WRITE)
1371 ring->st_wr_sect += preq.nr_sects;
1372
1373 return 0;
1374
1375 fail_flush:
1376 xen_blkbk_unmap(ring, pending_req->segments,
1377 pending_req->nr_segs);
1378 fail_response:
1379
1380 make_response(ring, req->u.rw.id, req_operation, BLKIF_RSP_ERROR);
1381 free_req(ring, pending_req);
1382 msleep(1);
1383 return -EIO;
1384
1385 fail_put_bio:
1386 for (i = 0; i < nbio; i++)
1387 bio_put(biolist[i]);
1388 atomic_set(&pending_req->pendcnt, 1);
1389 __end_block_io_op(pending_req, BLK_STS_RESOURCE);
1390 msleep(1);
1391 return -EIO;
1392}
1393
1394
1395
1396
1397
1398
1399static void make_response(struct xen_blkif_ring *ring, u64 id,
1400 unsigned short op, int st)
1401{
1402 struct blkif_response *resp;
1403 unsigned long flags;
1404 union blkif_back_rings *blk_rings;
1405 int notify;
1406
1407 spin_lock_irqsave(&ring->blk_ring_lock, flags);
1408 blk_rings = &ring->blk_rings;
1409
1410 switch (ring->blkif->blk_protocol) {
1411 case BLKIF_PROTOCOL_NATIVE:
1412 resp = RING_GET_RESPONSE(&blk_rings->native,
1413 blk_rings->native.rsp_prod_pvt);
1414 break;
1415 case BLKIF_PROTOCOL_X86_32:
1416 resp = RING_GET_RESPONSE(&blk_rings->x86_32,
1417 blk_rings->x86_32.rsp_prod_pvt);
1418 break;
1419 case BLKIF_PROTOCOL_X86_64:
1420 resp = RING_GET_RESPONSE(&blk_rings->x86_64,
1421 blk_rings->x86_64.rsp_prod_pvt);
1422 break;
1423 default:
1424 BUG();
1425 }
1426
1427 resp->id = id;
1428 resp->operation = op;
1429 resp->status = st;
1430
1431 blk_rings->common.rsp_prod_pvt++;
1432 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
1433 spin_unlock_irqrestore(&ring->blk_ring_lock, flags);
1434 if (notify)
1435 notify_remote_via_irq(ring->irq);
1436}
1437
1438static int __init xen_blkif_init(void)
1439{
1440 int rc = 0;
1441
1442 if (!xen_domain())
1443 return -ENODEV;
1444
1445 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
1446 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
1447 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
1448 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
1449 }
1450
1451 if (xenblk_max_queues == 0)
1452 xenblk_max_queues = num_online_cpus();
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
1466module_init(xen_blkif_init);
1467
1468static void __exit xen_blkif_fini(void)
1469{
1470 xen_blkif_xenbus_fini();
1471 xen_blkif_interface_fini();
1472}
1473
1474module_exit(xen_blkif_fini);
1475
1476MODULE_LICENSE("Dual BSD/GPL");
1477MODULE_ALIAS("xen-backend:vbd");
1478