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/drivers/block/xen-blkback/xenbus.c

https://bitbucket.org/ndreys/linux-sunxi
C | 767 lines | 572 code | 132 blank | 63 comment | 96 complexity | 917511f2fc00bc57cba0d6c4950896a6 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/*  Xenbus code for blkif backend
  2    Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
  3    Copyright (C) 2005 XenSource Ltd
  4
  5    This program is free software; you can redistribute it and/or modify
  6    it under the terms of the GNU General Public License as published by
  7    the Free Software Foundation; either version 2 of the License, or
  8    (at your option) any later version.
  9
 10    This program is distributed in the hope that it will be useful,
 11    but WITHOUT ANY WARRANTY; without even the implied warranty of
 12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13    GNU General Public License for more details.
 14
 15*/
 16
 17#include <stdarg.h>
 18#include <linux/module.h>
 19#include <linux/kthread.h>
 20#include <xen/events.h>
 21#include <xen/grant_table.h>
 22#include "common.h"
 23
 24struct backend_info {
 25	struct xenbus_device	*dev;
 26	struct xen_blkif	*blkif;
 27	struct xenbus_watch	backend_watch;
 28	unsigned		major;
 29	unsigned		minor;
 30	char			*mode;
 31};
 32
 33static struct kmem_cache *xen_blkif_cachep;
 34static void connect(struct backend_info *);
 35static int connect_ring(struct backend_info *);
 36static void backend_changed(struct xenbus_watch *, const char **,
 37			    unsigned int);
 38
 39struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
 40{
 41	return be->dev;
 42}
 43
 44static int blkback_name(struct xen_blkif *blkif, char *buf)
 45{
 46	char *devpath, *devname;
 47	struct xenbus_device *dev = blkif->be->dev;
 48
 49	devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
 50	if (IS_ERR(devpath))
 51		return PTR_ERR(devpath);
 52
 53	devname = strstr(devpath, "/dev/");
 54	if (devname != NULL)
 55		devname += strlen("/dev/");
 56	else
 57		devname  = devpath;
 58
 59	snprintf(buf, TASK_COMM_LEN, "blkback.%d.%s", blkif->domid, devname);
 60	kfree(devpath);
 61
 62	return 0;
 63}
 64
 65static void xen_update_blkif_status(struct xen_blkif *blkif)
 66{
 67	int err;
 68	char name[TASK_COMM_LEN];
 69
 70	/* Not ready to connect? */
 71	if (!blkif->irq || !blkif->vbd.bdev)
 72		return;
 73
 74	/* Already connected? */
 75	if (blkif->be->dev->state == XenbusStateConnected)
 76		return;
 77
 78	/* Attempt to connect: exit if we fail to. */
 79	connect(blkif->be);
 80	if (blkif->be->dev->state != XenbusStateConnected)
 81		return;
 82
 83	err = blkback_name(blkif, name);
 84	if (err) {
 85		xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
 86		return;
 87	}
 88
 89	err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
 90	if (err) {
 91		xenbus_dev_error(blkif->be->dev, err, "block flush");
 92		return;
 93	}
 94	invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
 95
 96	blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, name);
 97	if (IS_ERR(blkif->xenblkd)) {
 98		err = PTR_ERR(blkif->xenblkd);
 99		blkif->xenblkd = NULL;
100		xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
101	}
102}
103
104static struct xen_blkif *xen_blkif_alloc(domid_t domid)
105{
106	struct xen_blkif *blkif;
107
108	blkif = kmem_cache_alloc(xen_blkif_cachep, GFP_KERNEL);
109	if (!blkif)
110		return ERR_PTR(-ENOMEM);
111
112	memset(blkif, 0, sizeof(*blkif));
113	blkif->domid = domid;
114	spin_lock_init(&blkif->blk_ring_lock);
115	atomic_set(&blkif->refcnt, 1);
116	init_waitqueue_head(&blkif->wq);
117	blkif->st_print = jiffies;
118	init_waitqueue_head(&blkif->waiting_to_free);
119
120	return blkif;
121}
122
123static int map_frontend_page(struct xen_blkif *blkif, unsigned long shared_page)
124{
125	struct gnttab_map_grant_ref op;
126
127	gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
128			  GNTMAP_host_map, shared_page, blkif->domid);
129
130	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
131		BUG();
132
133	if (op.status) {
134		DPRINTK("Grant table operation failure !\n");
135		return op.status;
136	}
137
138	blkif->shmem_ref = shared_page;
139	blkif->shmem_handle = op.handle;
140
141	return 0;
142}
143
144static void unmap_frontend_page(struct xen_blkif *blkif)
145{
146	struct gnttab_unmap_grant_ref op;
147
148	gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
149			    GNTMAP_host_map, blkif->shmem_handle);
150
151	if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
152		BUG();
153}
154
155static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
156			 unsigned int evtchn)
157{
158	int err;
159
160	/* Already connected through? */
161	if (blkif->irq)
162		return 0;
163
164	blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE);
165	if (!blkif->blk_ring_area)
166		return -ENOMEM;
167
168	err = map_frontend_page(blkif, shared_page);
169	if (err) {
170		free_vm_area(blkif->blk_ring_area);
171		return err;
172	}
173
174	switch (blkif->blk_protocol) {
175	case BLKIF_PROTOCOL_NATIVE:
176	{
177		struct blkif_sring *sring;
178		sring = (struct blkif_sring *)blkif->blk_ring_area->addr;
179		BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
180		break;
181	}
182	case BLKIF_PROTOCOL_X86_32:
183	{
184		struct blkif_x86_32_sring *sring_x86_32;
185		sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring_area->addr;
186		BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
187		break;
188	}
189	case BLKIF_PROTOCOL_X86_64:
190	{
191		struct blkif_x86_64_sring *sring_x86_64;
192		sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;
193		BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
194		break;
195	}
196	default:
197		BUG();
198	}
199
200	err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
201						    xen_blkif_be_int, 0,
202						    "blkif-backend", blkif);
203	if (err < 0) {
204		unmap_frontend_page(blkif);
205		free_vm_area(blkif->blk_ring_area);
206		blkif->blk_rings.common.sring = NULL;
207		return err;
208	}
209	blkif->irq = err;
210
211	return 0;
212}
213
214static void xen_blkif_disconnect(struct xen_blkif *blkif)
215{
216	if (blkif->xenblkd) {
217		kthread_stop(blkif->xenblkd);
218		blkif->xenblkd = NULL;
219	}
220
221	atomic_dec(&blkif->refcnt);
222	wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
223	atomic_inc(&blkif->refcnt);
224
225	if (blkif->irq) {
226		unbind_from_irqhandler(blkif->irq, blkif);
227		blkif->irq = 0;
228	}
229
230	if (blkif->blk_rings.common.sring) {
231		unmap_frontend_page(blkif);
232		free_vm_area(blkif->blk_ring_area);
233		blkif->blk_rings.common.sring = NULL;
234	}
235}
236
237void xen_blkif_free(struct xen_blkif *blkif)
238{
239	if (!atomic_dec_and_test(&blkif->refcnt))
240		BUG();
241	kmem_cache_free(xen_blkif_cachep, blkif);
242}
243
244int __init xen_blkif_interface_init(void)
245{
246	xen_blkif_cachep = kmem_cache_create("blkif_cache",
247					     sizeof(struct xen_blkif),
248					     0, 0, NULL);
249	if (!xen_blkif_cachep)
250		return -ENOMEM;
251
252	return 0;
253}
254
255/*
256 *  sysfs interface for VBD I/O requests
257 */
258
259#define VBD_SHOW(name, format, args...)					\
260	static ssize_t show_##name(struct device *_dev,			\
261				   struct device_attribute *attr,	\
262				   char *buf)				\
263	{								\
264		struct xenbus_device *dev = to_xenbus_device(_dev);	\
265		struct backend_info *be = dev_get_drvdata(&dev->dev);	\
266									\
267		return sprintf(buf, format, ##args);			\
268	}								\
269	static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
270
271VBD_SHOW(oo_req,  "%d\n", be->blkif->st_oo_req);
272VBD_SHOW(rd_req,  "%d\n", be->blkif->st_rd_req);
273VBD_SHOW(wr_req,  "%d\n", be->blkif->st_wr_req);
274VBD_SHOW(f_req,  "%d\n", be->blkif->st_f_req);
275VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect);
276VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect);
277
278static struct attribute *xen_vbdstat_attrs[] = {
279	&dev_attr_oo_req.attr,
280	&dev_attr_rd_req.attr,
281	&dev_attr_wr_req.attr,
282	&dev_attr_f_req.attr,
283	&dev_attr_rd_sect.attr,
284	&dev_attr_wr_sect.attr,
285	NULL
286};
287
288static struct attribute_group xen_vbdstat_group = {
289	.name = "statistics",
290	.attrs = xen_vbdstat_attrs,
291};
292
293VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
294VBD_SHOW(mode, "%s\n", be->mode);
295
296int xenvbd_sysfs_addif(struct xenbus_device *dev)
297{
298	int error;
299
300	error = device_create_file(&dev->dev, &dev_attr_physical_device);
301	if (error)
302		goto fail1;
303
304	error = device_create_file(&dev->dev, &dev_attr_mode);
305	if (error)
306		goto fail2;
307
308	error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
309	if (error)
310		goto fail3;
311
312	return 0;
313
314fail3:	sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
315fail2:	device_remove_file(&dev->dev, &dev_attr_mode);
316fail1:	device_remove_file(&dev->dev, &dev_attr_physical_device);
317	return error;
318}
319
320void xenvbd_sysfs_delif(struct xenbus_device *dev)
321{
322	sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
323	device_remove_file(&dev->dev, &dev_attr_mode);
324	device_remove_file(&dev->dev, &dev_attr_physical_device);
325}
326
327
328static void xen_vbd_free(struct xen_vbd *vbd)
329{
330	if (vbd->bdev)
331		blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
332	vbd->bdev = NULL;
333}
334
335static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
336			  unsigned major, unsigned minor, int readonly,
337			  int cdrom)
338{
339	struct xen_vbd *vbd;
340	struct block_device *bdev;
341	struct request_queue *q;
342
343	vbd = &blkif->vbd;
344	vbd->handle   = handle;
345	vbd->readonly = readonly;
346	vbd->type     = 0;
347
348	vbd->pdevice  = MKDEV(major, minor);
349
350	bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
351				 FMODE_READ : FMODE_WRITE, NULL);
352
353	if (IS_ERR(bdev)) {
354		DPRINTK("xen_vbd_create: device %08x could not be opened.\n",
355			vbd->pdevice);
356		return -ENOENT;
357	}
358
359	vbd->bdev = bdev;
360	if (vbd->bdev->bd_disk == NULL) {
361		DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",
362			vbd->pdevice);
363		xen_vbd_free(vbd);
364		return -ENOENT;
365	}
366	vbd->size = vbd_sz(vbd);
367
368	if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
369		vbd->type |= VDISK_CDROM;
370	if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
371		vbd->type |= VDISK_REMOVABLE;
372
373	q = bdev_get_queue(bdev);
374	if (q && q->flush_flags)
375		vbd->flush_support = true;
376
377	DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
378		handle, blkif->domid);
379	return 0;
380}
381static int xen_blkbk_remove(struct xenbus_device *dev)
382{
383	struct backend_info *be = dev_get_drvdata(&dev->dev);
384
385	DPRINTK("");
386
387	if (be->major || be->minor)
388		xenvbd_sysfs_delif(dev);
389
390	if (be->backend_watch.node) {
391		unregister_xenbus_watch(&be->backend_watch);
392		kfree(be->backend_watch.node);
393		be->backend_watch.node = NULL;
394	}
395
396	if (be->blkif) {
397		xen_blkif_disconnect(be->blkif);
398		xen_vbd_free(&be->blkif->vbd);
399		xen_blkif_free(be->blkif);
400		be->blkif = NULL;
401	}
402
403	kfree(be);
404	dev_set_drvdata(&dev->dev, NULL);
405	return 0;
406}
407
408int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
409			      struct backend_info *be, int state)
410{
411	struct xenbus_device *dev = be->dev;
412	int err;
413
414	err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
415			    "%d", state);
416	if (err)
417		xenbus_dev_fatal(dev, err, "writing feature-flush-cache");
418
419	return err;
420}
421
422/*
423 * Entry point to this code when a new device is created.  Allocate the basic
424 * structures, and watch the store waiting for the hotplug scripts to tell us
425 * the device's physical major and minor numbers.  Switch to InitWait.
426 */
427static int xen_blkbk_probe(struct xenbus_device *dev,
428			   const struct xenbus_device_id *id)
429{
430	int err;
431	struct backend_info *be = kzalloc(sizeof(struct backend_info),
432					  GFP_KERNEL);
433	if (!be) {
434		xenbus_dev_fatal(dev, -ENOMEM,
435				 "allocating backend structure");
436		return -ENOMEM;
437	}
438	be->dev = dev;
439	dev_set_drvdata(&dev->dev, be);
440
441	be->blkif = xen_blkif_alloc(dev->otherend_id);
442	if (IS_ERR(be->blkif)) {
443		err = PTR_ERR(be->blkif);
444		be->blkif = NULL;
445		xenbus_dev_fatal(dev, err, "creating block interface");
446		goto fail;
447	}
448
449	/* setup back pointer */
450	be->blkif->be = be;
451
452	err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
453				   "%s/%s", dev->nodename, "physical-device");
454	if (err)
455		goto fail;
456
457	err = xenbus_switch_state(dev, XenbusStateInitWait);
458	if (err)
459		goto fail;
460
461	return 0;
462
463fail:
464	DPRINTK("failed");
465	xen_blkbk_remove(dev);
466	return err;
467}
468
469
470/*
471 * Callback received when the hotplug scripts have placed the physical-device
472 * node.  Read it and the mode node, and create a vbd.  If the frontend is
473 * ready, connect.
474 */
475static void backend_changed(struct xenbus_watch *watch,
476			    const char **vec, unsigned int len)
477{
478	int err;
479	unsigned major;
480	unsigned minor;
481	struct backend_info *be
482		= container_of(watch, struct backend_info, backend_watch);
483	struct xenbus_device *dev = be->dev;
484	int cdrom = 0;
485	char *device_type;
486
487	DPRINTK("");
488
489	err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
490			   &major, &minor);
491	if (XENBUS_EXIST_ERR(err)) {
492		/*
493		 * Since this watch will fire once immediately after it is
494		 * registered, we expect this.  Ignore it, and wait for the
495		 * hotplug scripts.
496		 */
497		return;
498	}
499	if (err != 2) {
500		xenbus_dev_fatal(dev, err, "reading physical-device");
501		return;
502	}
503
504	if ((be->major || be->minor) &&
505	    ((be->major != major) || (be->minor != minor))) {
506		pr_warn(DRV_PFX "changing physical device (from %x:%x to %x:%x) not supported.\n",
507			be->major, be->minor, major, minor);
508		return;
509	}
510
511	be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
512	if (IS_ERR(be->mode)) {
513		err = PTR_ERR(be->mode);
514		be->mode = NULL;
515		xenbus_dev_fatal(dev, err, "reading mode");
516		return;
517	}
518
519	device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
520	if (!IS_ERR(device_type)) {
521		cdrom = strcmp(device_type, "cdrom") == 0;
522		kfree(device_type);
523	}
524
525	if (be->major == 0 && be->minor == 0) {
526		/* Front end dir is a number, which is used as the handle. */
527
528		char *p = strrchr(dev->otherend, '/') + 1;
529		long handle;
530		err = strict_strtoul(p, 0, &handle);
531		if (err)
532			return;
533
534		be->major = major;
535		be->minor = minor;
536
537		err = xen_vbd_create(be->blkif, handle, major, minor,
538				 (NULL == strchr(be->mode, 'w')), cdrom);
539		if (err) {
540			be->major = 0;
541			be->minor = 0;
542			xenbus_dev_fatal(dev, err, "creating vbd structure");
543			return;
544		}
545
546		err = xenvbd_sysfs_addif(dev);
547		if (err) {
548			xen_vbd_free(&be->blkif->vbd);
549			be->major = 0;
550			be->minor = 0;
551			xenbus_dev_fatal(dev, err, "creating sysfs entries");
552			return;
553		}
554
555		/* We're potentially connected now */
556		xen_update_blkif_status(be->blkif);
557	}
558}
559
560
561/*
562 * Callback received when the frontend's state changes.
563 */
564static void frontend_changed(struct xenbus_device *dev,
565			     enum xenbus_state frontend_state)
566{
567	struct backend_info *be = dev_get_drvdata(&dev->dev);
568	int err;
569
570	DPRINTK("%s", xenbus_strstate(frontend_state));
571
572	switch (frontend_state) {
573	case XenbusStateInitialising:
574		if (dev->state == XenbusStateClosed) {
575			pr_info(DRV_PFX "%s: prepare for reconnect\n",
576				dev->nodename);
577			xenbus_switch_state(dev, XenbusStateInitWait);
578		}
579		break;
580
581	case XenbusStateInitialised:
582	case XenbusStateConnected:
583		/*
584		 * Ensure we connect even when two watches fire in
585		 * close successsion and we miss the intermediate value
586		 * of frontend_state.
587		 */
588		if (dev->state == XenbusStateConnected)
589			break;
590
591		/*
592		 * Enforce precondition before potential leak point.
593		 * blkif_disconnect() is idempotent.
594		 */
595		xen_blkif_disconnect(be->blkif);
596
597		err = connect_ring(be);
598		if (err)
599			break;
600		xen_update_blkif_status(be->blkif);
601		break;
602
603	case XenbusStateClosing:
604		xen_blkif_disconnect(be->blkif);
605		xenbus_switch_state(dev, XenbusStateClosing);
606		break;
607
608	case XenbusStateClosed:
609		xenbus_switch_state(dev, XenbusStateClosed);
610		if (xenbus_dev_is_online(dev))
611			break;
612		/* fall through if not online */
613	case XenbusStateUnknown:
614		/* implies blkif_disconnect() via blkback_remove() */
615		device_unregister(&dev->dev);
616		break;
617
618	default:
619		xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
620				 frontend_state);
621		break;
622	}
623}
624
625
626/* ** Connection ** */
627
628
629/*
630 * Write the physical details regarding the block device to the store, and
631 * switch to Connected state.
632 */
633static void connect(struct backend_info *be)
634{
635	struct xenbus_transaction xbt;
636	int err;
637	struct xenbus_device *dev = be->dev;
638
639	DPRINTK("%s", dev->otherend);
640
641	/* Supply the information about the device the frontend needs */
642again:
643	err = xenbus_transaction_start(&xbt);
644	if (err) {
645		xenbus_dev_fatal(dev, err, "starting transaction");
646		return;
647	}
648
649	err = xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
650	if (err)
651		goto abort;
652
653	err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
654			    (unsigned long long)vbd_sz(&be->blkif->vbd));
655	if (err) {
656		xenbus_dev_fatal(dev, err, "writing %s/sectors",
657				 dev->nodename);
658		goto abort;
659	}
660
661	/* FIXME: use a typename instead */
662	err = xenbus_printf(xbt, dev->nodename, "info", "%u",
663			    be->blkif->vbd.type |
664			    (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
665	if (err) {
666		xenbus_dev_fatal(dev, err, "writing %s/info",
667				 dev->nodename);
668		goto abort;
669	}
670	err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
671			    (unsigned long)
672			    bdev_logical_block_size(be->blkif->vbd.bdev));
673	if (err) {
674		xenbus_dev_fatal(dev, err, "writing %s/sector-size",
675				 dev->nodename);
676		goto abort;
677	}
678
679	err = xenbus_transaction_end(xbt, 0);
680	if (err == -EAGAIN)
681		goto again;
682	if (err)
683		xenbus_dev_fatal(dev, err, "ending transaction");
684
685	err = xenbus_switch_state(dev, XenbusStateConnected);
686	if (err)
687		xenbus_dev_fatal(dev, err, "switching to Connected state",
688				 dev->nodename);
689
690	return;
691 abort:
692	xenbus_transaction_end(xbt, 1);
693}
694
695
696static int connect_ring(struct backend_info *be)
697{
698	struct xenbus_device *dev = be->dev;
699	unsigned long ring_ref;
700	unsigned int evtchn;
701	char protocol[64] = "";
702	int err;
703
704	DPRINTK("%s", dev->otherend);
705
706	err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu",
707			    &ring_ref, "event-channel", "%u", &evtchn, NULL);
708	if (err) {
709		xenbus_dev_fatal(dev, err,
710				 "reading %s/ring-ref and event-channel",
711				 dev->otherend);
712		return err;
713	}
714
715	be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
716	err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
717			    "%63s", protocol, NULL);
718	if (err)
719		strcpy(protocol, "unspecified, assuming native");
720	else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
721		be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
722	else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
723		be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
724	else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
725		be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
726	else {
727		xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
728		return -1;
729	}
730	pr_info(DRV_PFX "ring-ref %ld, event-channel %d, protocol %d (%s)\n",
731		ring_ref, evtchn, be->blkif->blk_protocol, protocol);
732
733	/* Map the shared frame, irq etc. */
734	err = xen_blkif_map(be->blkif, ring_ref, evtchn);
735	if (err) {
736		xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u",
737				 ring_ref, evtchn);
738		return err;
739	}
740
741	return 0;
742}
743
744
745/* ** Driver Registration ** */
746
747
748static const struct xenbus_device_id xen_blkbk_ids[] = {
749	{ "vbd" },
750	{ "" }
751};
752
753
754static struct xenbus_driver xen_blkbk = {
755	.name = "vbd",
756	.owner = THIS_MODULE,
757	.ids = xen_blkbk_ids,
758	.probe = xen_blkbk_probe,
759	.remove = xen_blkbk_remove,
760	.otherend_changed = frontend_changed
761};
762
763
764int xen_blkif_xenbus_init(void)
765{
766	return xenbus_register_backend(&xen_blkbk);
767}