?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
WIP FPC-III support
[linux/fpc-iii.git] / drivers / block / xen-blkback / xenbus.c
blob9860d4842f36c7889e8e495464c5c02c7432e9cc
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 gnttab_page_cache_init(&ring->free_pages);
148
149 spin_lock_init(&ring->pending_free_lock);
150 init_waitqueue_head(&ring->pending_free_wq);
151 init_waitqueue_head(&ring->shutdown_wq);
152 ring->blkif = blkif;
153 ring->st_print = jiffies;
154 ring->active = true;
155 }
156
157 return 0;
158 }
159
160 static struct xen_blkif *xen_blkif_alloc(domid_t domid)
161 {
162 struct xen_blkif *blkif;
163
164 BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
165
166 blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL);
167 if (!blkif)
168 return ERR_PTR(-ENOMEM);
169
170 blkif->domid = domid;
171 atomic_set(&blkif->refcnt, 1);
172 init_completion(&blkif->drain_complete);
173
174 /*
175 * Because freeing back to the cache may be deferred, it is not
176 * safe to unload the module (and hence destroy the cache) until
177 * this has completed. To prevent premature unloading, take an
178 * extra module reference here and release only when the object
179 * has been freed back to the cache.
180 */
181 __module_get(THIS_MODULE);
182 INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
183
184 return blkif;
185 }
186
187 static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref,
188 unsigned int nr_grefs, unsigned int evtchn)
189 {
190 int err;
191 struct xen_blkif *blkif = ring->blkif;
192 const struct blkif_common_sring *sring_common;
193 RING_IDX rsp_prod, req_prod;
194 unsigned int size;
195
196 /* Already connected through? */
197 if (ring->irq)
198 return 0;
199
200 err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
201 &ring->blk_ring);
202 if (err < 0)
203 return err;
204
205 sring_common = (struct blkif_common_sring *)ring->blk_ring;
206 rsp_prod = READ_ONCE(sring_common->rsp_prod);
207 req_prod = READ_ONCE(sring_common->req_prod);
208
209 switch (blkif->blk_protocol) {
210 case BLKIF_PROTOCOL_NATIVE:
211 {
212 struct blkif_sring *sring_native =
213 (struct blkif_sring *)ring->blk_ring;
214
215 BACK_RING_ATTACH(&ring->blk_rings.native, sring_native,
216 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
217 size = __RING_SIZE(sring_native, XEN_PAGE_SIZE * nr_grefs);
218 break;
219 }
220 case BLKIF_PROTOCOL_X86_32:
221 {
222 struct blkif_x86_32_sring *sring_x86_32 =
223 (struct blkif_x86_32_sring *)ring->blk_ring;
224
225 BACK_RING_ATTACH(&ring->blk_rings.x86_32, sring_x86_32,
226 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
227 size = __RING_SIZE(sring_x86_32, XEN_PAGE_SIZE * nr_grefs);
228 break;
229 }
230 case BLKIF_PROTOCOL_X86_64:
231 {
232 struct blkif_x86_64_sring *sring_x86_64 =
233 (struct blkif_x86_64_sring *)ring->blk_ring;
234
235 BACK_RING_ATTACH(&ring->blk_rings.x86_64, sring_x86_64,
236 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
237 size = __RING_SIZE(sring_x86_64, XEN_PAGE_SIZE * nr_grefs);
238 break;
239 }
240 default:
241 BUG();
242 }
243
244 err = -EIO;
245 if (req_prod - rsp_prod > size)
246 goto fail;
247
248 err = bind_interdomain_evtchn_to_irqhandler_lateeoi(blkif->domid,
249 evtchn, xen_blkif_be_int, 0, "blkif-backend", ring);
250 if (err < 0)
251 goto fail;
252 ring->irq = err;
253
254 return 0;
255
256 fail:
257 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
258 ring->blk_rings.common.sring = NULL;
259 return err;
260 }
261
262 static int xen_blkif_disconnect(struct xen_blkif *blkif)
263 {
264 struct pending_req *req, *n;
265 unsigned int j, r;
266 bool busy = false;
267
268 for (r = 0; r < blkif->nr_rings; r++) {
269 struct xen_blkif_ring *ring = &blkif->rings[r];
270 unsigned int i = 0;
271
272 if (!ring->active)
273 continue;
274
275 if (ring->xenblkd) {
276 kthread_stop(ring->xenblkd);
277 ring->xenblkd = NULL;
278 wake_up(&ring->shutdown_wq);
279 }
280
281 /* The above kthread_stop() guarantees that at this point we
282 * don't have any discard_io or other_io requests. So, checking
283 * for inflight IO is enough.
284 */
285 if (atomic_read(&ring->inflight) > 0) {
286 busy = true;
287 continue;
288 }
289
290 if (ring->irq) {
291 unbind_from_irqhandler(ring->irq, ring);
292 ring->irq = 0;
293 }
294
295 if (ring->blk_rings.common.sring) {
296 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
297 ring->blk_rings.common.sring = NULL;
298 }
299
300 /* Remove all persistent grants and the cache of ballooned pages. */
301 xen_blkbk_free_caches(ring);
302
303 /* Check that there is no request in use */
304 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
305 list_del(&req->free_list);
306
307 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
308 kfree(req->segments[j]);
309
310 for (j = 0; j < MAX_INDIRECT_PAGES; j++)
311 kfree(req->indirect_pages[j]);
312
313 kfree(req);
314 i++;
315 }
316
317 BUG_ON(atomic_read(&ring->persistent_gnt_in_use) != 0);
318 BUG_ON(!list_empty(&ring->persistent_purge_list));
319 BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
320 BUG_ON(ring->free_pages.num_pages != 0);
321 BUG_ON(ring->persistent_gnt_c != 0);
322 WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
323 ring->active = false;
324 }
325 if (busy)
326 return -EBUSY;
327
328 blkif->nr_ring_pages = 0;
329 /*
330 * blkif->rings was allocated in connect_ring, so we should free it in
331 * here.
332 */
333 kfree(blkif->rings);
334 blkif->rings = NULL;
335 blkif->nr_rings = 0;
336
337 return 0;
338 }
339
340 static void xen_blkif_free(struct xen_blkif *blkif)
341 {
342 WARN_ON(xen_blkif_disconnect(blkif));
343 xen_vbd_free(&blkif->vbd);
344 kfree(blkif->be->mode);
345 kfree(blkif->be);
346
347 /* Make sure everything is drained before shutting down */
348 kmem_cache_free(xen_blkif_cachep, blkif);
349 module_put(THIS_MODULE);
350 }
351
352 int __init xen_blkif_interface_init(void)
353 {
354 xen_blkif_cachep = kmem_cache_create("blkif_cache",
355 sizeof(struct xen_blkif),
356 0, 0, NULL);
357 if (!xen_blkif_cachep)
358 return -ENOMEM;
359
360 return 0;
361 }
362
363 void xen_blkif_interface_fini(void)
364 {
365 kmem_cache_destroy(xen_blkif_cachep);
366 xen_blkif_cachep = NULL;
367 }
368
369 /*
370 * sysfs interface for VBD I/O requests
371 */
372
373 #define VBD_SHOW_ALLRING(name, format) \
374 static ssize_t show_##name(struct device *_dev, \
375 struct device_attribute *attr, \
376 char *buf) \
377 { \
378 struct xenbus_device *dev = to_xenbus_device(_dev); \
379 struct backend_info *be = dev_get_drvdata(&dev->dev); \
380 struct xen_blkif *blkif = be->blkif; \
381 unsigned int i; \
382 unsigned long long result = 0; \
383 \
384 if (!blkif->rings) \
385 goto out; \
386 \
387 for (i = 0; i < blkif->nr_rings; i++) { \
388 struct xen_blkif_ring *ring = &blkif->rings[i]; \
389 \
390 result += ring->st_##name; \
391 } \
392 \
393 out: \
394 return sprintf(buf, format, result); \
395 } \
396 static DEVICE_ATTR(name, 0444, show_##name, NULL)
397
398 VBD_SHOW_ALLRING(oo_req, "%llu\n");
399 VBD_SHOW_ALLRING(rd_req, "%llu\n");
400 VBD_SHOW_ALLRING(wr_req, "%llu\n");
401 VBD_SHOW_ALLRING(f_req, "%llu\n");
402 VBD_SHOW_ALLRING(ds_req, "%llu\n");
403 VBD_SHOW_ALLRING(rd_sect, "%llu\n");
404 VBD_SHOW_ALLRING(wr_sect, "%llu\n");
405
406 static struct attribute *xen_vbdstat_attrs[] = {
407 &dev_attr_oo_req.attr,
408 &dev_attr_rd_req.attr,
409 &dev_attr_wr_req.attr,
410 &dev_attr_f_req.attr,
411 &dev_attr_ds_req.attr,
412 &dev_attr_rd_sect.attr,
413 &dev_attr_wr_sect.attr,
414 NULL
415 };
416
417 static const struct attribute_group xen_vbdstat_group = {
418 .name = "statistics",
419 .attrs = xen_vbdstat_attrs,
420 };
421
422 #define VBD_SHOW(name, format, args...) \
423 static ssize_t show_##name(struct device *_dev, \
424 struct device_attribute *attr, \
425 char *buf) \
426 { \
427 struct xenbus_device *dev = to_xenbus_device(_dev); \
428 struct backend_info *be = dev_get_drvdata(&dev->dev); \
429 \
430 return sprintf(buf, format, ##args); \
431 } \
432 static DEVICE_ATTR(name, 0444, show_##name, NULL)
433
434 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
435 VBD_SHOW(mode, "%s\n", be->mode);
436
437 static int xenvbd_sysfs_addif(struct xenbus_device *dev)
438 {
439 int error;
440
441 error = device_create_file(&dev->dev, &dev_attr_physical_device);
442 if (error)
443 goto fail1;
444
445 error = device_create_file(&dev->dev, &dev_attr_mode);
446 if (error)
447 goto fail2;
448
449 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
450 if (error)
451 goto fail3;
452
453 return 0;
454
455 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
456 fail2: device_remove_file(&dev->dev, &dev_attr_mode);
457 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device);
458 return error;
459 }
460
461 static void xenvbd_sysfs_delif(struct xenbus_device *dev)
462 {
463 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
464 device_remove_file(&dev->dev, &dev_attr_mode);
465 device_remove_file(&dev->dev, &dev_attr_physical_device);
466 }
467
468 static void xen_vbd_free(struct xen_vbd *vbd)
469 {
470 if (vbd->bdev)
471 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
472 vbd->bdev = NULL;
473 }
474
475 /* Enable the persistent grants feature. */
476 static bool feature_persistent = true;
477 module_param(feature_persistent, bool, 0644);
478 MODULE_PARM_DESC(feature_persistent,
479 "Enables the persistent grants feature");
480
481 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
482 unsigned major, unsigned minor, int readonly,
483 int cdrom)
484 {
485 struct xen_vbd *vbd;
486 struct block_device *bdev;
487 struct request_queue *q;
488
489 vbd = &blkif->vbd;
490 vbd->handle = handle;
491 vbd->readonly = readonly;
492 vbd->type = 0;
493
494 vbd->pdevice = MKDEV(major, minor);
495
496 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
497 FMODE_READ : FMODE_WRITE, NULL);
498
499 if (IS_ERR(bdev)) {
500 pr_warn("xen_vbd_create: device %08x could not be opened\n",
501 vbd->pdevice);
502 return -ENOENT;
503 }
504
505 vbd->bdev = bdev;
506 if (vbd->bdev->bd_disk == NULL) {
507 pr_warn("xen_vbd_create: device %08x doesn't exist\n",
508 vbd->pdevice);
509 xen_vbd_free(vbd);
510 return -ENOENT;
511 }
512 vbd->size = vbd_sz(vbd);
513
514 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
515 vbd->type |= VDISK_CDROM;
516 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
517 vbd->type |= VDISK_REMOVABLE;
518
519 q = bdev_get_queue(bdev);
520 if (q && test_bit(QUEUE_FLAG_WC, &q->queue_flags))
521 vbd->flush_support = true;
522
523 if (q && blk_queue_secure_erase(q))
524 vbd->discard_secure = true;
525
526 vbd->feature_gnt_persistent = feature_persistent;
527
528 pr_debug("Successful creation of handle=%04x (dom=%u)\n",
529 handle, blkif->domid);
530 return 0;
531 }
532
533 static int xen_blkbk_remove(struct xenbus_device *dev)
534 {
535 struct backend_info *be = dev_get_drvdata(&dev->dev);
536
537 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
538
539 if (be->major || be->minor)
540 xenvbd_sysfs_delif(dev);
541
542 if (be->backend_watch.node) {
543 unregister_xenbus_watch(&be->backend_watch);
544 kfree(be->backend_watch.node);
545 be->backend_watch.node = NULL;
546 }
547
548 dev_set_drvdata(&dev->dev, NULL);
549
550 if (be->blkif) {
551 xen_blkif_disconnect(be->blkif);
552
553 /* Put the reference we set in xen_blkif_alloc(). */
554 xen_blkif_put(be->blkif);
555 }
556
557 return 0;
558 }
559
560 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
561 struct backend_info *be, int state)
562 {
563 struct xenbus_device *dev = be->dev;
564 int err;
565
566 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
567 "%d", state);
568 if (err)
569 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
570
571 return err;
572 }
573
574 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
575 {
576 struct xenbus_device *dev = be->dev;
577 struct xen_blkif *blkif = be->blkif;
578 int err;
579 int state = 0;
580 struct block_device *bdev = be->blkif->vbd.bdev;
581 struct request_queue *q = bdev_get_queue(bdev);
582
583 if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1))
584 return;
585
586 if (blk_queue_discard(q)) {
587 err = xenbus_printf(xbt, dev->nodename,
588 "discard-granularity", "%u",
589 q->limits.discard_granularity);
590 if (err) {
591 dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
592 return;
593 }
594 err = xenbus_printf(xbt, dev->nodename,
595 "discard-alignment", "%u",
596 q->limits.discard_alignment);
597 if (err) {
598 dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
599 return;
600 }
601 state = 1;
602 /* Optional. */
603 err = xenbus_printf(xbt, dev->nodename,
604 "discard-secure", "%d",
605 blkif->vbd.discard_secure);
606 if (err) {
607 dev_warn(&dev->dev, "writing discard-secure (%d)", err);
608 return;
609 }
610 }
611 err = xenbus_printf(xbt, dev->nodename, "feature-discard",
612 "%d", state);
613 if (err)
614 dev_warn(&dev->dev, "writing feature-discard (%d)", err);
615 }
616
617 int xen_blkbk_barrier(struct xenbus_transaction xbt,
618 struct backend_info *be, int state)
619 {
620 struct xenbus_device *dev = be->dev;
621 int err;
622
623 err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
624 "%d", state);
625 if (err)
626 dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
627
628 return err;
629 }
630
631 /*
632 * Entry point to this code when a new device is created. Allocate the basic
633 * structures, and watch the store waiting for the hotplug scripts to tell us
634 * the device's physical major and minor numbers. Switch to InitWait.
635 */
636 static int xen_blkbk_probe(struct xenbus_device *dev,
637 const struct xenbus_device_id *id)
638 {
639 int err;
640 struct backend_info *be = kzalloc(sizeof(struct backend_info),
641 GFP_KERNEL);
642
643 /* match the pr_debug in xen_blkbk_remove */
644 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
645
646 if (!be) {
647 xenbus_dev_fatal(dev, -ENOMEM,
648 "allocating backend structure");
649 return -ENOMEM;
650 }
651 be->dev = dev;
652 dev_set_drvdata(&dev->dev, be);
653
654 be->blkif = xen_blkif_alloc(dev->otherend_id);
655 if (IS_ERR(be->blkif)) {
656 err = PTR_ERR(be->blkif);
657 be->blkif = NULL;
658 xenbus_dev_fatal(dev, err, "creating block interface");
659 goto fail;
660 }
661
662 err = xenbus_printf(XBT_NIL, dev->nodename,
663 "feature-max-indirect-segments", "%u",
664 MAX_INDIRECT_SEGMENTS);
665 if (err)
666 dev_warn(&dev->dev,
667 "writing %s/feature-max-indirect-segments (%d)",
668 dev->nodename, err);
669
670 /* Multi-queue: advertise how many queues are supported by us.*/
671 err = xenbus_printf(XBT_NIL, dev->nodename,
672 "multi-queue-max-queues", "%u", xenblk_max_queues);
673 if (err)
674 pr_warn("Error writing multi-queue-max-queues\n");
675
676 /* setup back pointer */
677 be->blkif->be = be;
678
679 err = xenbus_watch_pathfmt(dev, &be->backend_watch, NULL,
680 backend_changed,
681 "%s/%s", dev->nodename, "physical-device");
682 if (err)
683 goto fail;
684
685 err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u",
686 xen_blkif_max_ring_order);
687 if (err)
688 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__);
689
690 err = xenbus_switch_state(dev, XenbusStateInitWait);
691 if (err)
692 goto fail;
693
694 return 0;
695
696 fail:
697 pr_warn("%s failed\n", __func__);
698 xen_blkbk_remove(dev);
699 return err;
700 }
701
702 /*
703 * Callback received when the hotplug scripts have placed the physical-device
704 * node. Read it and the mode node, and create a vbd. If the frontend is
705 * ready, connect.
706 */
707 static void backend_changed(struct xenbus_watch *watch,
708 const char *path, const char *token)
709 {
710 int err;
711 unsigned major;
712 unsigned minor;
713 struct backend_info *be
714 = container_of(watch, struct backend_info, backend_watch);
715 struct xenbus_device *dev = be->dev;
716 int cdrom = 0;
717 unsigned long handle;
718 char *device_type;
719
720 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
721
722 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
723 &major, &minor);
724 if (XENBUS_EXIST_ERR(err)) {
725 /*
726 * Since this watch will fire once immediately after it is
727 * registered, we expect this. Ignore it, and wait for the
728 * hotplug scripts.
729 */
730 return;
731 }
732 if (err != 2) {
733 xenbus_dev_fatal(dev, err, "reading physical-device");
734 return;
735 }
736
737 if (be->major | be->minor) {
738 if (be->major != major || be->minor != minor)
739 pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n",
740 be->major, be->minor, major, minor);
741 return;
742 }
743
744 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
745 if (IS_ERR(be->mode)) {
746 err = PTR_ERR(be->mode);
747 be->mode = NULL;
748 xenbus_dev_fatal(dev, err, "reading mode");
749 return;
750 }
751
752 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
753 if (!IS_ERR(device_type)) {
754 cdrom = strcmp(device_type, "cdrom") == 0;
755 kfree(device_type);
756 }
757
758 /* Front end dir is a number, which is used as the handle. */
759 err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle);
760 if (err) {
761 kfree(be->mode);
762 be->mode = NULL;
763 return;
764 }
765
766 be->major = major;
767 be->minor = minor;
768
769 err = xen_vbd_create(be->blkif, handle, major, minor,
770 !strchr(be->mode, 'w'), cdrom);
771
772 if (err)
773 xenbus_dev_fatal(dev, err, "creating vbd structure");
774 else {
775 err = xenvbd_sysfs_addif(dev);
776 if (err) {
777 xen_vbd_free(&be->blkif->vbd);
778 xenbus_dev_fatal(dev, err, "creating sysfs entries");
779 }
780 }
781
782 if (err) {
783 kfree(be->mode);
784 be->mode = NULL;
785 be->major = 0;
786 be->minor = 0;
787 } else {
788 /* We're potentially connected now */
789 xen_update_blkif_status(be->blkif);
790 }
791 }
792
793 /*
794 * Callback received when the frontend's state changes.
795 */
796 static void frontend_changed(struct xenbus_device *dev,
797 enum xenbus_state frontend_state)
798 {
799 struct backend_info *be = dev_get_drvdata(&dev->dev);
800 int err;
801
802 pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state));
803
804 switch (frontend_state) {
805 case XenbusStateInitialising:
806 if (dev->state == XenbusStateClosed) {
807 pr_info("%s: prepare for reconnect\n", dev->nodename);
808 xenbus_switch_state(dev, XenbusStateInitWait);
809 }
810 break;
811
812 case XenbusStateInitialised:
813 case XenbusStateConnected:
814 /*
815 * Ensure we connect even when two watches fire in
816 * close succession and we miss the intermediate value
817 * of frontend_state.
818 */
819 if (dev->state == XenbusStateConnected)
820 break;
821
822 /*
823 * Enforce precondition before potential leak point.
824 * xen_blkif_disconnect() is idempotent.
825 */
826 err = xen_blkif_disconnect(be->blkif);
827 if (err) {
828 xenbus_dev_fatal(dev, err, "pending I/O");
829 break;
830 }
831
832 err = connect_ring(be);
833 if (err) {
834 /*
835 * Clean up so that memory resources can be used by
836 * other devices. connect_ring reported already error.
837 */
838 xen_blkif_disconnect(be->blkif);
839 break;
840 }
841 xen_update_blkif_status(be->blkif);
842 break;
843
844 case XenbusStateClosing:
845 xenbus_switch_state(dev, XenbusStateClosing);
846 break;
847
848 case XenbusStateClosed:
849 xen_blkif_disconnect(be->blkif);
850 xenbus_switch_state(dev, XenbusStateClosed);
851 if (xenbus_dev_is_online(dev))
852 break;
853 fallthrough;
854 /* if not online */
855 case XenbusStateUnknown:
856 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
857 device_unregister(&dev->dev);
858 break;
859
860 default:
861 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
862 frontend_state);
863 break;
864 }
865 }
866
867 /* Once a memory pressure is detected, squeeze free page pools for a while. */
868 static unsigned int buffer_squeeze_duration_ms = 10;
869 module_param_named(buffer_squeeze_duration_ms,
870 buffer_squeeze_duration_ms, int, 0644);
871 MODULE_PARM_DESC(buffer_squeeze_duration_ms,
872 "Duration in ms to squeeze pages buffer when a memory pressure is detected");
873
874 /*
875 * Callback received when the memory pressure is detected.
876 */
877 static void reclaim_memory(struct xenbus_device *dev)
878 {
879 struct backend_info *be = dev_get_drvdata(&dev->dev);
880
881 if (!be)
882 return;
883 be->blkif->buffer_squeeze_end = jiffies +
884 msecs_to_jiffies(buffer_squeeze_duration_ms);
885 }
886
887 /* ** Connection ** */
888
889 /*
890 * Write the physical details regarding the block device to the store, and
891 * switch to Connected state.
892 */
893 static void connect(struct backend_info *be)
894 {
895 struct xenbus_transaction xbt;
896 int err;
897 struct xenbus_device *dev = be->dev;
898
899 pr_debug("%s %s\n", __func__, dev->otherend);
900
901 /* Supply the information about the device the frontend needs */
902 again:
903 err = xenbus_transaction_start(&xbt);
904 if (err) {
905 xenbus_dev_fatal(dev, err, "starting transaction");
906 return;
907 }
908
909 /* If we can't advertise it is OK. */
910 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
911
912 xen_blkbk_discard(xbt, be);
913
914 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
915
916 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
917 be->blkif->vbd.feature_gnt_persistent);
918 if (err) {
919 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent",
920 dev->nodename);
921 goto abort;
922 }
923
924 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
925 (unsigned long long)vbd_sz(&be->blkif->vbd));
926 if (err) {
927 xenbus_dev_fatal(dev, err, "writing %s/sectors",
928 dev->nodename);
929 goto abort;
930 }
931
932 /* FIXME: use a typename instead */
933 err = xenbus_printf(xbt, dev->nodename, "info", "%u",
934 be->blkif->vbd.type |
935 (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
936 if (err) {
937 xenbus_dev_fatal(dev, err, "writing %s/info",
938 dev->nodename);
939 goto abort;
940 }
941 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
942 (unsigned long)
943 bdev_logical_block_size(be->blkif->vbd.bdev));
944 if (err) {
945 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
946 dev->nodename);
947 goto abort;
948 }
949 err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u",
950 bdev_physical_block_size(be->blkif->vbd.bdev));
951 if (err)
952 xenbus_dev_error(dev, err, "writing %s/physical-sector-size",
953 dev->nodename);
954
955 err = xenbus_transaction_end(xbt, 0);
956 if (err == -EAGAIN)
957 goto again;
958 if (err)
959 xenbus_dev_fatal(dev, err, "ending transaction");
960
961 err = xenbus_switch_state(dev, XenbusStateConnected);
962 if (err)
963 xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
964 dev->nodename);
965
966 return;
967 abort:
968 xenbus_transaction_end(xbt, 1);
969 }
970
971 /*
972 * Each ring may have multi pages, depends on "ring-page-order".
973 */
974 static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
975 {
976 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
977 struct pending_req *req, *n;
978 int err, i, j;
979 struct xen_blkif *blkif = ring->blkif;
980 struct xenbus_device *dev = blkif->be->dev;
981 unsigned int nr_grefs, evtchn;
982
983 err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u",
984 &evtchn);
985 if (err != 1) {
986 err = -EINVAL;
987 xenbus_dev_fatal(dev, err, "reading %s/event-channel", dir);
988 return err;
989 }
990
991 nr_grefs = blkif->nr_ring_pages;
992
993 if (unlikely(!nr_grefs)) {
994 WARN_ON(true);
995 return -EINVAL;
996 }
997
998 for (i = 0; i < nr_grefs; i++) {
999 char ring_ref_name[RINGREF_NAME_LEN];
1000
1001 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1002 err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
1003 "%u", &ring_ref[i]);
1004
1005 if (err != 1) {
1006 if (nr_grefs == 1)
1007 break;
1008
1009 err = -EINVAL;
1010 xenbus_dev_fatal(dev, err, "reading %s/%s",
1011 dir, ring_ref_name);
1012 return err;
1013 }
1014 }
1015
1016 if (err != 1) {
1017 WARN_ON(nr_grefs != 1);
1018
1019 err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u",
1020 &ring_ref[0]);
1021 if (err != 1) {
1022 err = -EINVAL;
1023 xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir);
1024 return err;
1025 }
1026 }
1027
1028 err = -ENOMEM;
1029 for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
1030 req = kzalloc(sizeof(*req), GFP_KERNEL);
1031 if (!req)
1032 goto fail;
1033 list_add_tail(&req->free_list, &ring->pending_free);
1034 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
1035 req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL);
1036 if (!req->segments[j])
1037 goto fail;
1038 }
1039 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
1040 req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
1041 GFP_KERNEL);
1042 if (!req->indirect_pages[j])
1043 goto fail;
1044 }
1045 }
1046
1047 /* Map the shared frame, irq etc. */
1048 err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn);
1049 if (err) {
1050 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
1051 goto fail;
1052 }
1053
1054 return 0;
1055
1056 fail:
1057 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
1058 list_del(&req->free_list);
1059 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
1060 if (!req->segments[j])
1061 break;
1062 kfree(req->segments[j]);
1063 }
1064 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
1065 if (!req->indirect_pages[j])
1066 break;
1067 kfree(req->indirect_pages[j]);
1068 }
1069 kfree(req);
1070 }
1071 return err;
1072 }
1073
1074 static int connect_ring(struct backend_info *be)
1075 {
1076 struct xenbus_device *dev = be->dev;
1077 struct xen_blkif *blkif = be->blkif;
1078 char protocol[64] = "";
1079 int err, i;
1080 char *xspath;
1081 size_t xspathsize;
1082 const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
1083 unsigned int requested_num_queues = 0;
1084 unsigned int ring_page_order;
1085
1086 pr_debug("%s %s\n", __func__, dev->otherend);
1087
1088 blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
1089 err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol",
1090 "%63s", protocol);
1091 if (err <= 0)
1092 strcpy(protocol, "unspecified, assuming default");
1093 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
1094 blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
1095 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
1096 blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
1097 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
1098 blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
1099 else {
1100 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
1101 return -ENOSYS;
1102 }
1103 if (blkif->vbd.feature_gnt_persistent)
1104 blkif->vbd.feature_gnt_persistent =
1105 xenbus_read_unsigned(dev->otherend,
1106 "feature-persistent", 0);
1107
1108 blkif->vbd.overflow_max_grants = 0;
1109
1110 /*
1111 * Read the number of hardware queues from frontend.
1112 */
1113 requested_num_queues = xenbus_read_unsigned(dev->otherend,
1114 "multi-queue-num-queues",
1115 1);
1116 if (requested_num_queues > xenblk_max_queues
1117 || requested_num_queues == 0) {
1118 /* Buggy or malicious guest. */
1119 xenbus_dev_fatal(dev, err,
1120 "guest requested %u queues, exceeding the maximum of %u.",
1121 requested_num_queues, xenblk_max_queues);
1122 return -ENOSYS;
1123 }
1124 blkif->nr_rings = requested_num_queues;
1125 if (xen_blkif_alloc_rings(blkif))
1126 return -ENOMEM;
1127
1128 pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
1129 blkif->nr_rings, blkif->blk_protocol, protocol,
1130 blkif->vbd.feature_gnt_persistent ? "persistent grants" : "");
1131
1132 ring_page_order = xenbus_read_unsigned(dev->otherend,
1133 "ring-page-order", 0);
1134
1135 if (ring_page_order > xen_blkif_max_ring_order) {
1136 err = -EINVAL;
1137 xenbus_dev_fatal(dev, err,
1138 "requested ring page order %d exceed max:%d",
1139 ring_page_order,
1140 xen_blkif_max_ring_order);
1141 return err;
1142 }
1143
1144 blkif->nr_ring_pages = 1 << ring_page_order;
1145
1146 if (blkif->nr_rings == 1)
1147 return read_per_ring_refs(&blkif->rings[0], dev->otherend);
1148 else {
1149 xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
1150 xspath = kmalloc(xspathsize, GFP_KERNEL);
1151 if (!xspath) {
1152 xenbus_dev_fatal(dev, -ENOMEM, "reading ring references");
1153 return -ENOMEM;
1154 }
1155
1156 for (i = 0; i < blkif->nr_rings; i++) {
1157 memset(xspath, 0, xspathsize);
1158 snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i);
1159 err = read_per_ring_refs(&blkif->rings[i], xspath);
1160 if (err) {
1161 kfree(xspath);
1162 return err;
1163 }
1164 }
1165 kfree(xspath);
1166 }
1167 return 0;
1168 }
1169
1170 static const struct xenbus_device_id xen_blkbk_ids[] = {
1171 { "vbd" },
1172 { "" }
1173 };
1174
1175 static struct xenbus_driver xen_blkbk_driver = {
1176 .ids = xen_blkbk_ids,
1177 .probe = xen_blkbk_probe,
1178 .remove = xen_blkbk_remove,
1179 .otherend_changed = frontend_changed,
1180 .allow_rebind = true,
1181 .reclaim_memory = reclaim_memory,
1182 };
1183
1184 int xen_blkif_xenbus_init(void)
1185 {
1186 return xenbus_register_backend(&xen_blkbk_driver);
1187 }
1188
1189 void xen_blkif_xenbus_fini(void)
1190 {
1191 xenbus_unregister_driver(&xen_blkbk_driver);
1192 }
Linux with added FPC-III support