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arm64: dts: Revert "specify console via command line"
[linux/fpc-iii.git] / drivers / block / xen-blkback / xenbus.c
blob42944d41aea0385440b0bf67d3762ad4f904ba28
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Xenbus code for blkif backend
3 Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
4 Copyright (C) 2005 XenSource Ltd
5
6
7 */
8
9 #define pr_fmt(fmt) "xen-blkback: " fmt
10
11 #include <stdarg.h>
12 #include <linux/module.h>
13 #include <linux/kthread.h>
14 #include <xen/events.h>
15 #include <xen/grant_table.h>
16 #include "common.h"
17
18 /* On the XenBus the max length of 'ring-ref%u'. */
19 #define RINGREF_NAME_LEN (20)
20
21 struct backend_info {
22 struct xenbus_device *dev;
23 struct xen_blkif *blkif;
24 struct xenbus_watch backend_watch;
25 unsigned major;
26 unsigned minor;
27 char *mode;
28 };
29
30 static struct kmem_cache *xen_blkif_cachep;
31 static void connect(struct backend_info *);
32 static int connect_ring(struct backend_info *);
33 static void backend_changed(struct xenbus_watch *, const char *,
34 const char *);
35 static void xen_blkif_free(struct xen_blkif *blkif);
36 static void xen_vbd_free(struct xen_vbd *vbd);
37
38 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
39 {
40 return be->dev;
41 }
42
43 /*
44 * The last request could free the device from softirq context and
45 * xen_blkif_free() can sleep.
46 */
47 static void xen_blkif_deferred_free(struct work_struct *work)
48 {
49 struct xen_blkif *blkif;
50
51 blkif = container_of(work, struct xen_blkif, free_work);
52 xen_blkif_free(blkif);
53 }
54
55 static int blkback_name(struct xen_blkif *blkif, char *buf)
56 {
57 char *devpath, *devname;
58 struct xenbus_device *dev = blkif->be->dev;
59
60 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
61 if (IS_ERR(devpath))
62 return PTR_ERR(devpath);
63
64 devname = strstr(devpath, "/dev/");
65 if (devname != NULL)
66 devname += strlen("/dev/");
67 else
68 devname = devpath;
69
70 snprintf(buf, TASK_COMM_LEN, "%d.%s", blkif->domid, devname);
71 kfree(devpath);
72
73 return 0;
74 }
75
76 static void xen_update_blkif_status(struct xen_blkif *blkif)
77 {
78 int err;
79 char name[TASK_COMM_LEN];
80 struct xen_blkif_ring *ring;
81 int i;
82
83 /* Not ready to connect? */
84 if (!blkif->rings || !blkif->rings[0].irq || !blkif->vbd.bdev)
85 return;
86
87 /* Already connected? */
88 if (blkif->be->dev->state == XenbusStateConnected)
89 return;
90
91 /* Attempt to connect: exit if we fail to. */
92 connect(blkif->be);
93 if (blkif->be->dev->state != XenbusStateConnected)
94 return;
95
96 err = blkback_name(blkif, name);
97 if (err) {
98 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
99 return;
100 }
101
102 err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
103 if (err) {
104 xenbus_dev_error(blkif->be->dev, err, "block flush");
105 return;
106 }
107 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
108
109 for (i = 0; i < blkif->nr_rings; i++) {
110 ring = &blkif->rings[i];
111 ring->xenblkd = kthread_run(xen_blkif_schedule, ring, "%s-%d", name, i);
112 if (IS_ERR(ring->xenblkd)) {
113 err = PTR_ERR(ring->xenblkd);
114 ring->xenblkd = NULL;
115 xenbus_dev_fatal(blkif->be->dev, err,
116 "start %s-%d xenblkd", name, i);
117 goto out;
118 }
119 }
120 return;
121
122 out:
123 while (--i >= 0) {
124 ring = &blkif->rings[i];
125 kthread_stop(ring->xenblkd);
126 }
127 return;
128 }
129
130 static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
131 {
132 unsigned int r;
133
134 blkif->rings = kcalloc(blkif->nr_rings, sizeof(struct xen_blkif_ring),
135 GFP_KERNEL);
136 if (!blkif->rings)
137 return -ENOMEM;
138
139 for (r = 0; r < blkif->nr_rings; r++) {
140 struct xen_blkif_ring *ring = &blkif->rings[r];
141
142 spin_lock_init(&ring->blk_ring_lock);
143 init_waitqueue_head(&ring->wq);
144 INIT_LIST_HEAD(&ring->pending_free);
145 INIT_LIST_HEAD(&ring->persistent_purge_list);
146 INIT_WORK(&ring->persistent_purge_work, xen_blkbk_unmap_purged_grants);
147 spin_lock_init(&ring->free_pages_lock);
148 INIT_LIST_HEAD(&ring->free_pages);
149
150 spin_lock_init(&ring->pending_free_lock);
151 init_waitqueue_head(&ring->pending_free_wq);
152 init_waitqueue_head(&ring->shutdown_wq);
153 ring->blkif = blkif;
154 ring->st_print = jiffies;
155 ring->active = true;
156 }
157
158 return 0;
159 }
160
161 static struct xen_blkif *xen_blkif_alloc(domid_t domid)
162 {
163 struct xen_blkif *blkif;
164
165 BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
166
167 blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL);
168 if (!blkif)
169 return ERR_PTR(-ENOMEM);
170
171 blkif->domid = domid;
172 atomic_set(&blkif->refcnt, 1);
173 init_completion(&blkif->drain_complete);
174
175 /*
176 * Because freeing back to the cache may be deferred, it is not
177 * safe to unload the module (and hence destroy the cache) until
178 * this has completed. To prevent premature unloading, take an
179 * extra module reference here and release only when the object
180 * has been freed back to the cache.
181 */
182 __module_get(THIS_MODULE);
183 INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
184
185 return blkif;
186 }
187
188 static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref,
189 unsigned int nr_grefs, unsigned int evtchn)
190 {
191 int err;
192 struct xen_blkif *blkif = ring->blkif;
193 const struct blkif_common_sring *sring_common;
194 RING_IDX rsp_prod, req_prod;
195 unsigned int size;
196
197 /* Already connected through? */
198 if (ring->irq)
199 return 0;
200
201 err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
202 &ring->blk_ring);
203 if (err < 0)
204 return err;
205
206 sring_common = (struct blkif_common_sring *)ring->blk_ring;
207 rsp_prod = READ_ONCE(sring_common->rsp_prod);
208 req_prod = READ_ONCE(sring_common->req_prod);
209
210 switch (blkif->blk_protocol) {
211 case BLKIF_PROTOCOL_NATIVE:
212 {
213 struct blkif_sring *sring_native =
214 (struct blkif_sring *)ring->blk_ring;
215
216 BACK_RING_ATTACH(&ring->blk_rings.native, sring_native,
217 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
218 size = __RING_SIZE(sring_native, XEN_PAGE_SIZE * nr_grefs);
219 break;
220 }
221 case BLKIF_PROTOCOL_X86_32:
222 {
223 struct blkif_x86_32_sring *sring_x86_32 =
224 (struct blkif_x86_32_sring *)ring->blk_ring;
225
226 BACK_RING_ATTACH(&ring->blk_rings.x86_32, sring_x86_32,
227 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
228 size = __RING_SIZE(sring_x86_32, XEN_PAGE_SIZE * nr_grefs);
229 break;
230 }
231 case BLKIF_PROTOCOL_X86_64:
232 {
233 struct blkif_x86_64_sring *sring_x86_64 =
234 (struct blkif_x86_64_sring *)ring->blk_ring;
235
236 BACK_RING_ATTACH(&ring->blk_rings.x86_64, sring_x86_64,
237 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
238 size = __RING_SIZE(sring_x86_64, XEN_PAGE_SIZE * nr_grefs);
239 break;
240 }
241 default:
242 BUG();
243 }
244
245 err = -EIO;
246 if (req_prod - rsp_prod > size)
247 goto fail;
248
249 err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
250 xen_blkif_be_int, 0,
251 "blkif-backend", ring);
252 if (err < 0)
253 goto fail;
254 ring->irq = err;
255
256 return 0;
257
258 fail:
259 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
260 ring->blk_rings.common.sring = NULL;
261 return err;
262 }
263
264 static int xen_blkif_disconnect(struct xen_blkif *blkif)
265 {
266 struct pending_req *req, *n;
267 unsigned int j, r;
268 bool busy = false;
269
270 for (r = 0; r < blkif->nr_rings; r++) {
271 struct xen_blkif_ring *ring = &blkif->rings[r];
272 unsigned int i = 0;
273
274 if (!ring->active)
275 continue;
276
277 if (ring->xenblkd) {
278 kthread_stop(ring->xenblkd);
279 wake_up(&ring->shutdown_wq);
280 }
281
282 /* The above kthread_stop() guarantees that at this point we
283 * don't have any discard_io or other_io requests. So, checking
284 * for inflight IO is enough.
285 */
286 if (atomic_read(&ring->inflight) > 0) {
287 busy = true;
288 continue;
289 }
290
291 if (ring->irq) {
292 unbind_from_irqhandler(ring->irq, ring);
293 ring->irq = 0;
294 }
295
296 if (ring->blk_rings.common.sring) {
297 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
298 ring->blk_rings.common.sring = NULL;
299 }
300
301 /* Remove all persistent grants and the cache of ballooned pages. */
302 xen_blkbk_free_caches(ring);
303
304 /* Check that there is no request in use */
305 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
306 list_del(&req->free_list);
307
308 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
309 kfree(req->segments[j]);
310
311 for (j = 0; j < MAX_INDIRECT_PAGES; j++)
312 kfree(req->indirect_pages[j]);
313
314 kfree(req);
315 i++;
316 }
317
318 BUG_ON(atomic_read(&ring->persistent_gnt_in_use) != 0);
319 BUG_ON(!list_empty(&ring->persistent_purge_list));
320 BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
321 BUG_ON(!list_empty(&ring->free_pages));
322 BUG_ON(ring->free_pages_num != 0);
323 BUG_ON(ring->persistent_gnt_c != 0);
324 WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
325 ring->active = false;
326 }
327 if (busy)
328 return -EBUSY;
329
330 blkif->nr_ring_pages = 0;
331 /*
332 * blkif->rings was allocated in connect_ring, so we should free it in
333 * here.
334 */
335 kfree(blkif->rings);
336 blkif->rings = NULL;
337 blkif->nr_rings = 0;
338
339 return 0;
340 }
341
342 static void xen_blkif_free(struct xen_blkif *blkif)
343 {
344 WARN_ON(xen_blkif_disconnect(blkif));
345 xen_vbd_free(&blkif->vbd);
346 kfree(blkif->be->mode);
347 kfree(blkif->be);
348
349 /* Make sure everything is drained before shutting down */
350 kmem_cache_free(xen_blkif_cachep, blkif);
351 module_put(THIS_MODULE);
352 }
353
354 int __init xen_blkif_interface_init(void)
355 {
356 xen_blkif_cachep = kmem_cache_create("blkif_cache",
357 sizeof(struct xen_blkif),
358 0, 0, NULL);
359 if (!xen_blkif_cachep)
360 return -ENOMEM;
361
362 return 0;
363 }
364
365 void xen_blkif_interface_fini(void)
366 {
367 kmem_cache_destroy(xen_blkif_cachep);
368 xen_blkif_cachep = NULL;
369 }
370
371 /*
372 * sysfs interface for VBD I/O requests
373 */
374
375 #define VBD_SHOW_ALLRING(name, format) \
376 static ssize_t show_##name(struct device *_dev, \
377 struct device_attribute *attr, \
378 char *buf) \
379 { \
380 struct xenbus_device *dev = to_xenbus_device(_dev); \
381 struct backend_info *be = dev_get_drvdata(&dev->dev); \
382 struct xen_blkif *blkif = be->blkif; \
383 unsigned int i; \
384 unsigned long long result = 0; \
385 \
386 if (!blkif->rings) \
387 goto out; \
388 \
389 for (i = 0; i < blkif->nr_rings; i++) { \
390 struct xen_blkif_ring *ring = &blkif->rings[i]; \
391 \
392 result += ring->st_##name; \
393 } \
394 \
395 out: \
396 return sprintf(buf, format, result); \
397 } \
398 static DEVICE_ATTR(name, 0444, show_##name, NULL)
399
400 VBD_SHOW_ALLRING(oo_req, "%llu\n");
401 VBD_SHOW_ALLRING(rd_req, "%llu\n");
402 VBD_SHOW_ALLRING(wr_req, "%llu\n");
403 VBD_SHOW_ALLRING(f_req, "%llu\n");
404 VBD_SHOW_ALLRING(ds_req, "%llu\n");
405 VBD_SHOW_ALLRING(rd_sect, "%llu\n");
406 VBD_SHOW_ALLRING(wr_sect, "%llu\n");
407
408 static struct attribute *xen_vbdstat_attrs[] = {
409 &dev_attr_oo_req.attr,
410 &dev_attr_rd_req.attr,
411 &dev_attr_wr_req.attr,
412 &dev_attr_f_req.attr,
413 &dev_attr_ds_req.attr,
414 &dev_attr_rd_sect.attr,
415 &dev_attr_wr_sect.attr,
416 NULL
417 };
418
419 static const struct attribute_group xen_vbdstat_group = {
420 .name = "statistics",
421 .attrs = xen_vbdstat_attrs,
422 };
423
424 #define VBD_SHOW(name, format, args...) \
425 static ssize_t show_##name(struct device *_dev, \
426 struct device_attribute *attr, \
427 char *buf) \
428 { \
429 struct xenbus_device *dev = to_xenbus_device(_dev); \
430 struct backend_info *be = dev_get_drvdata(&dev->dev); \
431 \
432 return sprintf(buf, format, ##args); \
433 } \
434 static DEVICE_ATTR(name, 0444, show_##name, NULL)
435
436 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
437 VBD_SHOW(mode, "%s\n", be->mode);
438
439 static int xenvbd_sysfs_addif(struct xenbus_device *dev)
440 {
441 int error;
442
443 error = device_create_file(&dev->dev, &dev_attr_physical_device);
444 if (error)
445 goto fail1;
446
447 error = device_create_file(&dev->dev, &dev_attr_mode);
448 if (error)
449 goto fail2;
450
451 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
452 if (error)
453 goto fail3;
454
455 return 0;
456
457 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
458 fail2: device_remove_file(&dev->dev, &dev_attr_mode);
459 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device);
460 return error;
461 }
462
463 static void xenvbd_sysfs_delif(struct xenbus_device *dev)
464 {
465 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
466 device_remove_file(&dev->dev, &dev_attr_mode);
467 device_remove_file(&dev->dev, &dev_attr_physical_device);
468 }
469
470 static void xen_vbd_free(struct xen_vbd *vbd)
471 {
472 if (vbd->bdev)
473 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
474 vbd->bdev = NULL;
475 }
476
477 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
478 unsigned major, unsigned minor, int readonly,
479 int cdrom)
480 {
481 struct xen_vbd *vbd;
482 struct block_device *bdev;
483 struct request_queue *q;
484
485 vbd = &blkif->vbd;
486 vbd->handle = handle;
487 vbd->readonly = readonly;
488 vbd->type = 0;
489
490 vbd->pdevice = MKDEV(major, minor);
491
492 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
493 FMODE_READ : FMODE_WRITE, NULL);
494
495 if (IS_ERR(bdev)) {
496 pr_warn("xen_vbd_create: device %08x could not be opened\n",
497 vbd->pdevice);
498 return -ENOENT;
499 }
500
501 vbd->bdev = bdev;
502 if (vbd->bdev->bd_disk == NULL) {
503 pr_warn("xen_vbd_create: device %08x doesn't exist\n",
504 vbd->pdevice);
505 xen_vbd_free(vbd);
506 return -ENOENT;
507 }
508 vbd->size = vbd_sz(vbd);
509
510 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
511 vbd->type |= VDISK_CDROM;
512 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
513 vbd->type |= VDISK_REMOVABLE;
514
515 q = bdev_get_queue(bdev);
516 if (q && test_bit(QUEUE_FLAG_WC, &q->queue_flags))
517 vbd->flush_support = true;
518
519 if (q && blk_queue_secure_erase(q))
520 vbd->discard_secure = true;
521
522 pr_debug("Successful creation of handle=%04x (dom=%u)\n",
523 handle, blkif->domid);
524 return 0;
525 }
526
527 static int xen_blkbk_remove(struct xenbus_device *dev)
528 {
529 struct backend_info *be = dev_get_drvdata(&dev->dev);
530
531 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
532
533 if (be->major || be->minor)
534 xenvbd_sysfs_delif(dev);
535
536 if (be->backend_watch.node) {
537 unregister_xenbus_watch(&be->backend_watch);
538 kfree(be->backend_watch.node);
539 be->backend_watch.node = NULL;
540 }
541
542 dev_set_drvdata(&dev->dev, NULL);
543
544 if (be->blkif) {
545 xen_blkif_disconnect(be->blkif);
546
547 /* Put the reference we set in xen_blkif_alloc(). */
548 xen_blkif_put(be->blkif);
549 }
550
551 return 0;
552 }
553
554 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
555 struct backend_info *be, int state)
556 {
557 struct xenbus_device *dev = be->dev;
558 int err;
559
560 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
561 "%d", state);
562 if (err)
563 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
564
565 return err;
566 }
567
568 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
569 {
570 struct xenbus_device *dev = be->dev;
571 struct xen_blkif *blkif = be->blkif;
572 int err;
573 int state = 0;
574 struct block_device *bdev = be->blkif->vbd.bdev;
575 struct request_queue *q = bdev_get_queue(bdev);
576
577 if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1))
578 return;
579
580 if (blk_queue_discard(q)) {
581 err = xenbus_printf(xbt, dev->nodename,
582 "discard-granularity", "%u",
583 q->limits.discard_granularity);
584 if (err) {
585 dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
586 return;
587 }
588 err = xenbus_printf(xbt, dev->nodename,
589 "discard-alignment", "%u",
590 q->limits.discard_alignment);
591 if (err) {
592 dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
593 return;
594 }
595 state = 1;
596 /* Optional. */
597 err = xenbus_printf(xbt, dev->nodename,
598 "discard-secure", "%d",
599 blkif->vbd.discard_secure);
600 if (err) {
601 dev_warn(&dev->dev, "writing discard-secure (%d)", err);
602 return;
603 }
604 }
605 err = xenbus_printf(xbt, dev->nodename, "feature-discard",
606 "%d", state);
607 if (err)
608 dev_warn(&dev->dev, "writing feature-discard (%d)", err);
609 }
610
611 int xen_blkbk_barrier(struct xenbus_transaction xbt,
612 struct backend_info *be, int state)
613 {
614 struct xenbus_device *dev = be->dev;
615 int err;
616
617 err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
618 "%d", state);
619 if (err)
620 dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
621
622 return err;
623 }
624
625 /*
626 * Entry point to this code when a new device is created. Allocate the basic
627 * structures, and watch the store waiting for the hotplug scripts to tell us
628 * the device's physical major and minor numbers. Switch to InitWait.
629 */
630 static int xen_blkbk_probe(struct xenbus_device *dev,
631 const struct xenbus_device_id *id)
632 {
633 int err;
634 struct backend_info *be = kzalloc(sizeof(struct backend_info),
635 GFP_KERNEL);
636
637 /* match the pr_debug in xen_blkbk_remove */
638 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
639
640 if (!be) {
641 xenbus_dev_fatal(dev, -ENOMEM,
642 "allocating backend structure");
643 return -ENOMEM;
644 }
645 be->dev = dev;
646 dev_set_drvdata(&dev->dev, be);
647
648 be->blkif = xen_blkif_alloc(dev->otherend_id);
649 if (IS_ERR(be->blkif)) {
650 err = PTR_ERR(be->blkif);
651 be->blkif = NULL;
652 xenbus_dev_fatal(dev, err, "creating block interface");
653 goto fail;
654 }
655
656 err = xenbus_printf(XBT_NIL, dev->nodename,
657 "feature-max-indirect-segments", "%u",
658 MAX_INDIRECT_SEGMENTS);
659 if (err)
660 dev_warn(&dev->dev,
661 "writing %s/feature-max-indirect-segments (%d)",
662 dev->nodename, err);
663
664 /* Multi-queue: advertise how many queues are supported by us.*/
665 err = xenbus_printf(XBT_NIL, dev->nodename,
666 "multi-queue-max-queues", "%u", xenblk_max_queues);
667 if (err)
668 pr_warn("Error writing multi-queue-max-queues\n");
669
670 /* setup back pointer */
671 be->blkif->be = be;
672
673 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
674 "%s/%s", dev->nodename, "physical-device");
675 if (err)
676 goto fail;
677
678 err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u",
679 xen_blkif_max_ring_order);
680 if (err)
681 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__);
682
683 err = xenbus_switch_state(dev, XenbusStateInitWait);
684 if (err)
685 goto fail;
686
687 return 0;
688
689 fail:
690 pr_warn("%s failed\n", __func__);
691 xen_blkbk_remove(dev);
692 return err;
693 }
694
695 /*
696 * Callback received when the hotplug scripts have placed the physical-device
697 * node. Read it and the mode node, and create a vbd. If the frontend is
698 * ready, connect.
699 */
700 static void backend_changed(struct xenbus_watch *watch,
701 const char *path, const char *token)
702 {
703 int err;
704 unsigned major;
705 unsigned minor;
706 struct backend_info *be
707 = container_of(watch, struct backend_info, backend_watch);
708 struct xenbus_device *dev = be->dev;
709 int cdrom = 0;
710 unsigned long handle;
711 char *device_type;
712
713 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
714
715 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
716 &major, &minor);
717 if (XENBUS_EXIST_ERR(err)) {
718 /*
719 * Since this watch will fire once immediately after it is
720 * registered, we expect this. Ignore it, and wait for the
721 * hotplug scripts.
722 */
723 return;
724 }
725 if (err != 2) {
726 xenbus_dev_fatal(dev, err, "reading physical-device");
727 return;
728 }
729
730 if (be->major | be->minor) {
731 if (be->major != major || be->minor != minor)
732 pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n",
733 be->major, be->minor, major, minor);
734 return;
735 }
736
737 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
738 if (IS_ERR(be->mode)) {
739 err = PTR_ERR(be->mode);
740 be->mode = NULL;
741 xenbus_dev_fatal(dev, err, "reading mode");
742 return;
743 }
744
745 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
746 if (!IS_ERR(device_type)) {
747 cdrom = strcmp(device_type, "cdrom") == 0;
748 kfree(device_type);
749 }
750
751 /* Front end dir is a number, which is used as the handle. */
752 err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle);
753 if (err) {
754 kfree(be->mode);
755 be->mode = NULL;
756 return;
757 }
758
759 be->major = major;
760 be->minor = minor;
761
762 err = xen_vbd_create(be->blkif, handle, major, minor,
763 !strchr(be->mode, 'w'), cdrom);
764
765 if (err)
766 xenbus_dev_fatal(dev, err, "creating vbd structure");
767 else {
768 err = xenvbd_sysfs_addif(dev);
769 if (err) {
770 xen_vbd_free(&be->blkif->vbd);
771 xenbus_dev_fatal(dev, err, "creating sysfs entries");
772 }
773 }
774
775 if (err) {
776 kfree(be->mode);
777 be->mode = NULL;
778 be->major = 0;
779 be->minor = 0;
780 } else {
781 /* We're potentially connected now */
782 xen_update_blkif_status(be->blkif);
783 }
784 }
785
786 /*
787 * Callback received when the frontend's state changes.
788 */
789 static void frontend_changed(struct xenbus_device *dev,
790 enum xenbus_state frontend_state)
791 {
792 struct backend_info *be = dev_get_drvdata(&dev->dev);
793 int err;
794
795 pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state));
796
797 switch (frontend_state) {
798 case XenbusStateInitialising:
799 if (dev->state == XenbusStateClosed) {
800 pr_info("%s: prepare for reconnect\n", dev->nodename);
801 xenbus_switch_state(dev, XenbusStateInitWait);
802 }
803 break;
804
805 case XenbusStateInitialised:
806 case XenbusStateConnected:
807 /*
808 * Ensure we connect even when two watches fire in
809 * close succession and we miss the intermediate value
810 * of frontend_state.
811 */
812 if (dev->state == XenbusStateConnected)
813 break;
814
815 /*
816 * Enforce precondition before potential leak point.
817 * xen_blkif_disconnect() is idempotent.
818 */
819 err = xen_blkif_disconnect(be->blkif);
820 if (err) {
821 xenbus_dev_fatal(dev, err, "pending I/O");
822 break;
823 }
824
825 err = connect_ring(be);
826 if (err) {
827 /*
828 * Clean up so that memory resources can be used by
829 * other devices. connect_ring reported already error.
830 */
831 xen_blkif_disconnect(be->blkif);
832 break;
833 }
834 xen_update_blkif_status(be->blkif);
835 break;
836
837 case XenbusStateClosing:
838 xenbus_switch_state(dev, XenbusStateClosing);
839 break;
840
841 case XenbusStateClosed:
842 xen_blkif_disconnect(be->blkif);
843 xenbus_switch_state(dev, XenbusStateClosed);
844 if (xenbus_dev_is_online(dev))
845 break;
846 /* fall through */
847 /* if not online */
848 case XenbusStateUnknown:
849 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
850 device_unregister(&dev->dev);
851 break;
852
853 default:
854 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
855 frontend_state);
856 break;
857 }
858 }
859
860 /* Once a memory pressure is detected, squeeze free page pools for a while. */
861 static unsigned int buffer_squeeze_duration_ms = 10;
862 module_param_named(buffer_squeeze_duration_ms,
863 buffer_squeeze_duration_ms, int, 0644);
864 MODULE_PARM_DESC(buffer_squeeze_duration_ms,
865 "Duration in ms to squeeze pages buffer when a memory pressure is detected");
866
867 /*
868 * Callback received when the memory pressure is detected.
869 */
870 static void reclaim_memory(struct xenbus_device *dev)
871 {
872 struct backend_info *be = dev_get_drvdata(&dev->dev);
873
874 if (!be)
875 return;
876 be->blkif->buffer_squeeze_end = jiffies +
877 msecs_to_jiffies(buffer_squeeze_duration_ms);
878 }
879
880 /* ** Connection ** */
881
882 /*
883 * Write the physical details regarding the block device to the store, and
884 * switch to Connected state.
885 */
886 static void connect(struct backend_info *be)
887 {
888 struct xenbus_transaction xbt;
889 int err;
890 struct xenbus_device *dev = be->dev;
891
892 pr_debug("%s %s\n", __func__, dev->otherend);
893
894 /* Supply the information about the device the frontend needs */
895 again:
896 err = xenbus_transaction_start(&xbt);
897 if (err) {
898 xenbus_dev_fatal(dev, err, "starting transaction");
899 return;
900 }
901
902 /* If we can't advertise it is OK. */
903 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
904
905 xen_blkbk_discard(xbt, be);
906
907 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
908
909 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1);
910 if (err) {
911 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent",
912 dev->nodename);
913 goto abort;
914 }
915
916 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
917 (unsigned long long)vbd_sz(&be->blkif->vbd));
918 if (err) {
919 xenbus_dev_fatal(dev, err, "writing %s/sectors",
920 dev->nodename);
921 goto abort;
922 }
923
924 /* FIXME: use a typename instead */
925 err = xenbus_printf(xbt, dev->nodename, "info", "%u",
926 be->blkif->vbd.type |
927 (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
928 if (err) {
929 xenbus_dev_fatal(dev, err, "writing %s/info",
930 dev->nodename);
931 goto abort;
932 }
933 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
934 (unsigned long)
935 bdev_logical_block_size(be->blkif->vbd.bdev));
936 if (err) {
937 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
938 dev->nodename);
939 goto abort;
940 }
941 err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u",
942 bdev_physical_block_size(be->blkif->vbd.bdev));
943 if (err)
944 xenbus_dev_error(dev, err, "writing %s/physical-sector-size",
945 dev->nodename);
946
947 err = xenbus_transaction_end(xbt, 0);
948 if (err == -EAGAIN)
949 goto again;
950 if (err)
951 xenbus_dev_fatal(dev, err, "ending transaction");
952
953 err = xenbus_switch_state(dev, XenbusStateConnected);
954 if (err)
955 xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
956 dev->nodename);
957
958 return;
959 abort:
960 xenbus_transaction_end(xbt, 1);
961 }
962
963 /*
964 * Each ring may have multi pages, depends on "ring-page-order".
965 */
966 static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
967 {
968 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
969 struct pending_req *req, *n;
970 int err, i, j;
971 struct xen_blkif *blkif = ring->blkif;
972 struct xenbus_device *dev = blkif->be->dev;
973 unsigned int nr_grefs, evtchn;
974
975 err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u",
976 &evtchn);
977 if (err != 1) {
978 err = -EINVAL;
979 xenbus_dev_fatal(dev, err, "reading %s/event-channel", dir);
980 return err;
981 }
982
983 nr_grefs = blkif->nr_ring_pages;
984
985 if (unlikely(!nr_grefs)) {
986 WARN_ON(true);
987 return -EINVAL;
988 }
989
990 for (i = 0; i < nr_grefs; i++) {
991 char ring_ref_name[RINGREF_NAME_LEN];
992
993 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
994 err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
995 "%u", &ring_ref[i]);
996
997 if (err != 1) {
998 if (nr_grefs == 1)
999 break;
1000
1001 err = -EINVAL;
1002 xenbus_dev_fatal(dev, err, "reading %s/%s",
1003 dir, ring_ref_name);
1004 return err;
1005 }
1006 }
1007
1008 if (err != 1) {
1009 WARN_ON(nr_grefs != 1);
1010
1011 err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u",
1012 &ring_ref[0]);
1013 if (err != 1) {
1014 err = -EINVAL;
1015 xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir);
1016 return err;
1017 }
1018 }
1019
1020 err = -ENOMEM;
1021 for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
1022 req = kzalloc(sizeof(*req), GFP_KERNEL);
1023 if (!req)
1024 goto fail;
1025 list_add_tail(&req->free_list, &ring->pending_free);
1026 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
1027 req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL);
1028 if (!req->segments[j])
1029 goto fail;
1030 }
1031 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
1032 req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
1033 GFP_KERNEL);
1034 if (!req->indirect_pages[j])
1035 goto fail;
1036 }
1037 }
1038
1039 /* Map the shared frame, irq etc. */
1040 err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn);
1041 if (err) {
1042 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
1043 goto fail;
1044 }
1045
1046 return 0;
1047
1048 fail:
1049 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
1050 list_del(&req->free_list);
1051 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
1052 if (!req->segments[j])
1053 break;
1054 kfree(req->segments[j]);
1055 }
1056 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
1057 if (!req->indirect_pages[j])
1058 break;
1059 kfree(req->indirect_pages[j]);
1060 }
1061 kfree(req);
1062 }
1063 return err;
1064 }
1065
1066 static int connect_ring(struct backend_info *be)
1067 {
1068 struct xenbus_device *dev = be->dev;
1069 struct xen_blkif *blkif = be->blkif;
1070 unsigned int pers_grants;
1071 char protocol[64] = "";
1072 int err, i;
1073 char *xspath;
1074 size_t xspathsize;
1075 const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
1076 unsigned int requested_num_queues = 0;
1077 unsigned int ring_page_order;
1078
1079 pr_debug("%s %s\n", __func__, dev->otherend);
1080
1081 blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
1082 err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol",
1083 "%63s", protocol);
1084 if (err <= 0)
1085 strcpy(protocol, "unspecified, assuming default");
1086 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
1087 blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
1088 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
1089 blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
1090 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
1091 blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
1092 else {
1093 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
1094 return -ENOSYS;
1095 }
1096 pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent",
1097 0);
1098 blkif->vbd.feature_gnt_persistent = pers_grants;
1099 blkif->vbd.overflow_max_grants = 0;
1100
1101 /*
1102 * Read the number of hardware queues from frontend.
1103 */
1104 requested_num_queues = xenbus_read_unsigned(dev->otherend,
1105 "multi-queue-num-queues",
1106 1);
1107 if (requested_num_queues > xenblk_max_queues
1108 || requested_num_queues == 0) {
1109 /* Buggy or malicious guest. */
1110 xenbus_dev_fatal(dev, err,
1111 "guest requested %u queues, exceeding the maximum of %u.",
1112 requested_num_queues, xenblk_max_queues);
1113 return -ENOSYS;
1114 }
1115 blkif->nr_rings = requested_num_queues;
1116 if (xen_blkif_alloc_rings(blkif))
1117 return -ENOMEM;
1118
1119 pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
1120 blkif->nr_rings, blkif->blk_protocol, protocol,
1121 pers_grants ? "persistent grants" : "");
1122
1123 ring_page_order = xenbus_read_unsigned(dev->otherend,
1124 "ring-page-order", 0);
1125
1126 if (ring_page_order > xen_blkif_max_ring_order) {
1127 err = -EINVAL;
1128 xenbus_dev_fatal(dev, err,
1129 "requested ring page order %d exceed max:%d",
1130 ring_page_order,
1131 xen_blkif_max_ring_order);
1132 return err;
1133 }
1134
1135 blkif->nr_ring_pages = 1 << ring_page_order;
1136
1137 if (blkif->nr_rings == 1)
1138 return read_per_ring_refs(&blkif->rings[0], dev->otherend);
1139 else {
1140 xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
1141 xspath = kmalloc(xspathsize, GFP_KERNEL);
1142 if (!xspath) {
1143 xenbus_dev_fatal(dev, -ENOMEM, "reading ring references");
1144 return -ENOMEM;
1145 }
1146
1147 for (i = 0; i < blkif->nr_rings; i++) {
1148 memset(xspath, 0, xspathsize);
1149 snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i);
1150 err = read_per_ring_refs(&blkif->rings[i], xspath);
1151 if (err) {
1152 kfree(xspath);
1153 return err;
1154 }
1155 }
1156 kfree(xspath);
1157 }
1158 return 0;
1159 }
1160
1161 static const struct xenbus_device_id xen_blkbk_ids[] = {
1162 { "vbd" },
1163 { "" }
1164 };
1165
1166 static struct xenbus_driver xen_blkbk_driver = {
1167 .ids = xen_blkbk_ids,
1168 .probe = xen_blkbk_probe,
1169 .remove = xen_blkbk_remove,
1170 .otherend_changed = frontend_changed,
1171 .allow_rebind = true,
1172 .reclaim_memory = reclaim_memory,
1173 };
1174
1175 int xen_blkif_xenbus_init(void)
1176 {
1177 return xenbus_register_backend(&xen_blkbk_driver);
1178 }
1179
1180 void xen_blkif_xenbus_fini(void)
1181 {
1182 xenbus_unregister_driver(&xen_blkbk_driver);
1183 }
Linux with added FPC-III support