1 /* Xenbus code for blkif backend
2 Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
3 Copyright (C) 2005 XenSource Ltd
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.
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.
17 #define pr_fmt(fmt) "xen-blkback: " fmt
20 #include <linux/module.h>
21 #include <linux/kthread.h>
22 #include <xen/events.h>
23 #include <xen/grant_table.h>
26 /* Enlarge the array size in order to fully show blkback name. */
27 #define BLKBACK_NAME_LEN (20)
28 #define RINGREF_NAME_LEN (20)
31 struct xenbus_device *dev;
32 struct xen_blkif *blkif;
33 struct xenbus_watch backend_watch;
39 static struct kmem_cache *xen_blkif_cachep;
40 static void connect(struct backend_info *);
41 static int connect_ring(struct backend_info *);
42 static void backend_changed(struct xenbus_watch *, const char **,
44 static void xen_blkif_free(struct xen_blkif *blkif);
45 static void xen_vbd_free(struct xen_vbd *vbd);
47 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
53 * The last request could free the device from softirq context and
54 * xen_blkif_free() can sleep.
56 static void xen_blkif_deferred_free(struct work_struct *work)
58 struct xen_blkif *blkif;
60 blkif = container_of(work, struct xen_blkif, free_work);
61 xen_blkif_free(blkif);
64 static int blkback_name(struct xen_blkif *blkif, char *buf)
66 char *devpath, *devname;
67 struct xenbus_device *dev = blkif->be->dev;
69 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
71 return PTR_ERR(devpath);
73 devname = strstr(devpath, "/dev/");
75 devname += strlen("/dev/");
79 snprintf(buf, BLKBACK_NAME_LEN, "blkback.%d.%s", blkif->domid, devname);
85 static void xen_update_blkif_status(struct xen_blkif *blkif)
88 char name[BLKBACK_NAME_LEN];
90 /* Not ready to connect? */
91 if (!blkif->irq || !blkif->vbd.bdev)
94 /* Already connected? */
95 if (blkif->be->dev->state == XenbusStateConnected)
98 /* Attempt to connect: exit if we fail to. */
100 if (blkif->be->dev->state != XenbusStateConnected)
103 err = blkback_name(blkif, name);
105 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
109 err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
111 xenbus_dev_error(blkif->be->dev, err, "block flush");
114 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
116 blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, "%s", name);
117 if (IS_ERR(blkif->xenblkd)) {
118 err = PTR_ERR(blkif->xenblkd);
119 blkif->xenblkd = NULL;
120 xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
125 static struct xen_blkif *xen_blkif_alloc(domid_t domid)
127 struct xen_blkif *blkif;
129 BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
131 blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL);
133 return ERR_PTR(-ENOMEM);
135 blkif->domid = domid;
136 spin_lock_init(&blkif->blk_ring_lock);
137 atomic_set(&blkif->refcnt, 1);
138 init_waitqueue_head(&blkif->wq);
139 init_completion(&blkif->drain_complete);
140 atomic_set(&blkif->drain, 0);
141 blkif->st_print = jiffies;
142 blkif->persistent_gnts.rb_node = NULL;
143 spin_lock_init(&blkif->free_pages_lock);
144 INIT_LIST_HEAD(&blkif->free_pages);
145 INIT_LIST_HEAD(&blkif->persistent_purge_list);
146 blkif->free_pages_num = 0;
147 atomic_set(&blkif->persistent_gnt_in_use, 0);
148 atomic_set(&blkif->inflight, 0);
149 INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants);
151 INIT_LIST_HEAD(&blkif->pending_free);
152 INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
153 spin_lock_init(&blkif->pending_free_lock);
154 init_waitqueue_head(&blkif->pending_free_wq);
155 init_waitqueue_head(&blkif->shutdown_wq);
160 static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
161 unsigned int nr_grefs, unsigned int evtchn)
165 /* Already connected through? */
169 err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
174 switch (blkif->blk_protocol) {
175 case BLKIF_PROTOCOL_NATIVE:
177 struct blkif_sring *sring;
178 sring = (struct blkif_sring *)blkif->blk_ring;
179 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE * nr_grefs);
182 case BLKIF_PROTOCOL_X86_32:
184 struct blkif_x86_32_sring *sring_x86_32;
185 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
186 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE * nr_grefs);
189 case BLKIF_PROTOCOL_X86_64:
191 struct blkif_x86_64_sring *sring_x86_64;
192 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
193 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE * nr_grefs);
200 err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
202 "blkif-backend", blkif);
204 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
205 blkif->blk_rings.common.sring = NULL;
213 static int xen_blkif_disconnect(struct xen_blkif *blkif)
215 struct pending_req *req, *n;
218 if (blkif->xenblkd) {
219 kthread_stop(blkif->xenblkd);
220 wake_up(&blkif->shutdown_wq);
221 blkif->xenblkd = NULL;
224 /* The above kthread_stop() guarantees that at this point we
225 * don't have any discard_io or other_io requests. So, checking
226 * for inflight IO is enough.
228 if (atomic_read(&blkif->inflight) > 0)
232 unbind_from_irqhandler(blkif->irq, blkif);
236 if (blkif->blk_rings.common.sring) {
237 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
238 blkif->blk_rings.common.sring = NULL;
241 /* Remove all persistent grants and the cache of ballooned pages. */
242 xen_blkbk_free_caches(blkif);
244 /* Check that there is no request in use */
245 list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
246 list_del(&req->free_list);
248 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
249 kfree(req->segments[j]);
251 for (j = 0; j < MAX_INDIRECT_PAGES; j++)
252 kfree(req->indirect_pages[j]);
258 WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
259 blkif->nr_ring_pages = 0;
264 static void xen_blkif_free(struct xen_blkif *blkif)
267 xen_blkif_disconnect(blkif);
268 xen_vbd_free(&blkif->vbd);
270 /* Make sure everything is drained before shutting down */
271 BUG_ON(blkif->persistent_gnt_c != 0);
272 BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0);
273 BUG_ON(blkif->free_pages_num != 0);
274 BUG_ON(!list_empty(&blkif->persistent_purge_list));
275 BUG_ON(!list_empty(&blkif->free_pages));
276 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
278 kmem_cache_free(xen_blkif_cachep, blkif);
281 int __init xen_blkif_interface_init(void)
283 xen_blkif_cachep = kmem_cache_create("blkif_cache",
284 sizeof(struct xen_blkif),
286 if (!xen_blkif_cachep)
293 * sysfs interface for VBD I/O requests
296 #define VBD_SHOW(name, format, args...) \
297 static ssize_t show_##name(struct device *_dev, \
298 struct device_attribute *attr, \
301 struct xenbus_device *dev = to_xenbus_device(_dev); \
302 struct backend_info *be = dev_get_drvdata(&dev->dev); \
304 return sprintf(buf, format, ##args); \
306 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
308 VBD_SHOW(oo_req, "%llu\n", be->blkif->st_oo_req);
309 VBD_SHOW(rd_req, "%llu\n", be->blkif->st_rd_req);
310 VBD_SHOW(wr_req, "%llu\n", be->blkif->st_wr_req);
311 VBD_SHOW(f_req, "%llu\n", be->blkif->st_f_req);
312 VBD_SHOW(ds_req, "%llu\n", be->blkif->st_ds_req);
313 VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect);
314 VBD_SHOW(wr_sect, "%llu\n", be->blkif->st_wr_sect);
316 static struct attribute *xen_vbdstat_attrs[] = {
317 &dev_attr_oo_req.attr,
318 &dev_attr_rd_req.attr,
319 &dev_attr_wr_req.attr,
320 &dev_attr_f_req.attr,
321 &dev_attr_ds_req.attr,
322 &dev_attr_rd_sect.attr,
323 &dev_attr_wr_sect.attr,
327 static struct attribute_group xen_vbdstat_group = {
328 .name = "statistics",
329 .attrs = xen_vbdstat_attrs,
332 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
333 VBD_SHOW(mode, "%s\n", be->mode);
335 static int xenvbd_sysfs_addif(struct xenbus_device *dev)
339 error = device_create_file(&dev->dev, &dev_attr_physical_device);
343 error = device_create_file(&dev->dev, &dev_attr_mode);
347 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
353 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
354 fail2: device_remove_file(&dev->dev, &dev_attr_mode);
355 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device);
359 static void xenvbd_sysfs_delif(struct xenbus_device *dev)
361 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
362 device_remove_file(&dev->dev, &dev_attr_mode);
363 device_remove_file(&dev->dev, &dev_attr_physical_device);
367 static void xen_vbd_free(struct xen_vbd *vbd)
370 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
374 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
375 unsigned major, unsigned minor, int readonly,
379 struct block_device *bdev;
380 struct request_queue *q;
383 vbd->handle = handle;
384 vbd->readonly = readonly;
387 vbd->pdevice = MKDEV(major, minor);
389 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
390 FMODE_READ : FMODE_WRITE, NULL);
393 pr_warn("xen_vbd_create: device %08x could not be opened\n",
399 if (vbd->bdev->bd_disk == NULL) {
400 pr_warn("xen_vbd_create: device %08x doesn't exist\n",
405 vbd->size = vbd_sz(vbd);
407 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
408 vbd->type |= VDISK_CDROM;
409 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
410 vbd->type |= VDISK_REMOVABLE;
412 q = bdev_get_queue(bdev);
413 if (q && q->flush_flags)
414 vbd->flush_support = true;
416 if (q && blk_queue_secdiscard(q))
417 vbd->discard_secure = true;
419 pr_debug("Successful creation of handle=%04x (dom=%u)\n",
420 handle, blkif->domid);
423 static int xen_blkbk_remove(struct xenbus_device *dev)
425 struct backend_info *be = dev_get_drvdata(&dev->dev);
427 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
429 if (be->major || be->minor)
430 xenvbd_sysfs_delif(dev);
432 if (be->backend_watch.node) {
433 unregister_xenbus_watch(&be->backend_watch);
434 kfree(be->backend_watch.node);
435 be->backend_watch.node = NULL;
438 dev_set_drvdata(&dev->dev, NULL);
441 xen_blkif_disconnect(be->blkif);
442 xen_blkif_put(be->blkif);
450 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
451 struct backend_info *be, int state)
453 struct xenbus_device *dev = be->dev;
456 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
459 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
464 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
466 struct xenbus_device *dev = be->dev;
467 struct xen_blkif *blkif = be->blkif;
469 int state = 0, discard_enable;
470 struct block_device *bdev = be->blkif->vbd.bdev;
471 struct request_queue *q = bdev_get_queue(bdev);
473 err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d",
475 if (err == 1 && !discard_enable)
478 if (blk_queue_discard(q)) {
479 err = xenbus_printf(xbt, dev->nodename,
480 "discard-granularity", "%u",
481 q->limits.discard_granularity);
483 dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
486 err = xenbus_printf(xbt, dev->nodename,
487 "discard-alignment", "%u",
488 q->limits.discard_alignment);
490 dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
495 err = xenbus_printf(xbt, dev->nodename,
496 "discard-secure", "%d",
497 blkif->vbd.discard_secure);
499 dev_warn(&dev->dev, "writing discard-secure (%d)", err);
503 err = xenbus_printf(xbt, dev->nodename, "feature-discard",
506 dev_warn(&dev->dev, "writing feature-discard (%d)", err);
508 int xen_blkbk_barrier(struct xenbus_transaction xbt,
509 struct backend_info *be, int state)
511 struct xenbus_device *dev = be->dev;
514 err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
517 dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
523 * Entry point to this code when a new device is created. Allocate the basic
524 * structures, and watch the store waiting for the hotplug scripts to tell us
525 * the device's physical major and minor numbers. Switch to InitWait.
527 static int xen_blkbk_probe(struct xenbus_device *dev,
528 const struct xenbus_device_id *id)
531 struct backend_info *be = kzalloc(sizeof(struct backend_info),
534 /* match the pr_debug in xen_blkbk_remove */
535 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
538 xenbus_dev_fatal(dev, -ENOMEM,
539 "allocating backend structure");
543 dev_set_drvdata(&dev->dev, be);
545 be->blkif = xen_blkif_alloc(dev->otherend_id);
546 if (IS_ERR(be->blkif)) {
547 err = PTR_ERR(be->blkif);
549 xenbus_dev_fatal(dev, err, "creating block interface");
553 /* setup back pointer */
556 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
557 "%s/%s", dev->nodename, "physical-device");
561 err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u",
562 xen_blkif_max_ring_order);
564 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__);
566 err = xenbus_switch_state(dev, XenbusStateInitWait);
573 pr_warn("%s failed\n", __func__);
574 xen_blkbk_remove(dev);
580 * Callback received when the hotplug scripts have placed the physical-device
581 * node. Read it and the mode node, and create a vbd. If the frontend is
584 static void backend_changed(struct xenbus_watch *watch,
585 const char **vec, unsigned int len)
590 struct backend_info *be
591 = container_of(watch, struct backend_info, backend_watch);
592 struct xenbus_device *dev = be->dev;
594 unsigned long handle;
597 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
599 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
601 if (XENBUS_EXIST_ERR(err)) {
603 * Since this watch will fire once immediately after it is
604 * registered, we expect this. Ignore it, and wait for the
610 xenbus_dev_fatal(dev, err, "reading physical-device");
614 if (be->major | be->minor) {
615 if (be->major != major || be->minor != minor)
616 pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n",
617 be->major, be->minor, major, minor);
621 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
622 if (IS_ERR(be->mode)) {
623 err = PTR_ERR(be->mode);
625 xenbus_dev_fatal(dev, err, "reading mode");
629 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
630 if (!IS_ERR(device_type)) {
631 cdrom = strcmp(device_type, "cdrom") == 0;
635 /* Front end dir is a number, which is used as the handle. */
636 err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle);
643 err = xen_vbd_create(be->blkif, handle, major, minor,
644 !strchr(be->mode, 'w'), cdrom);
647 xenbus_dev_fatal(dev, err, "creating vbd structure");
649 err = xenvbd_sysfs_addif(dev);
651 xen_vbd_free(&be->blkif->vbd);
652 xenbus_dev_fatal(dev, err, "creating sysfs entries");
662 /* We're potentially connected now */
663 xen_update_blkif_status(be->blkif);
669 * Callback received when the frontend's state changes.
671 static void frontend_changed(struct xenbus_device *dev,
672 enum xenbus_state frontend_state)
674 struct backend_info *be = dev_get_drvdata(&dev->dev);
677 pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state));
679 switch (frontend_state) {
680 case XenbusStateInitialising:
681 if (dev->state == XenbusStateClosed) {
682 pr_info("%s: prepare for reconnect\n", dev->nodename);
683 xenbus_switch_state(dev, XenbusStateInitWait);
687 case XenbusStateInitialised:
688 case XenbusStateConnected:
690 * Ensure we connect even when two watches fire in
691 * close succession and we miss the intermediate value
694 if (dev->state == XenbusStateConnected)
698 * Enforce precondition before potential leak point.
699 * xen_blkif_disconnect() is idempotent.
701 err = xen_blkif_disconnect(be->blkif);
703 xenbus_dev_fatal(dev, err, "pending I/O");
707 err = connect_ring(be);
710 xen_update_blkif_status(be->blkif);
713 case XenbusStateClosing:
714 xenbus_switch_state(dev, XenbusStateClosing);
717 case XenbusStateClosed:
718 xen_blkif_disconnect(be->blkif);
719 xenbus_switch_state(dev, XenbusStateClosed);
720 if (xenbus_dev_is_online(dev))
722 /* fall through if not online */
723 case XenbusStateUnknown:
724 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
725 device_unregister(&dev->dev);
729 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
736 /* ** Connection ** */
740 * Write the physical details regarding the block device to the store, and
741 * switch to Connected state.
743 static void connect(struct backend_info *be)
745 struct xenbus_transaction xbt;
747 struct xenbus_device *dev = be->dev;
749 pr_debug("%s %s\n", __func__, dev->otherend);
751 /* Supply the information about the device the frontend needs */
753 err = xenbus_transaction_start(&xbt);
755 xenbus_dev_fatal(dev, err, "starting transaction");
759 /* If we can't advertise it is OK. */
760 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
762 xen_blkbk_discard(xbt, be);
764 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
766 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1);
768 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent",
772 err = xenbus_printf(xbt, dev->nodename, "feature-max-indirect-segments", "%u",
773 MAX_INDIRECT_SEGMENTS);
775 dev_warn(&dev->dev, "writing %s/feature-max-indirect-segments (%d)",
778 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
779 (unsigned long long)vbd_sz(&be->blkif->vbd));
781 xenbus_dev_fatal(dev, err, "writing %s/sectors",
786 /* FIXME: use a typename instead */
787 err = xenbus_printf(xbt, dev->nodename, "info", "%u",
788 be->blkif->vbd.type |
789 (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
791 xenbus_dev_fatal(dev, err, "writing %s/info",
795 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
797 bdev_logical_block_size(be->blkif->vbd.bdev));
799 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
803 err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u",
804 bdev_physical_block_size(be->blkif->vbd.bdev));
806 xenbus_dev_error(dev, err, "writing %s/physical-sector-size",
809 err = xenbus_transaction_end(xbt, 0);
813 xenbus_dev_fatal(dev, err, "ending transaction");
815 err = xenbus_switch_state(dev, XenbusStateConnected);
817 xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
822 xenbus_transaction_end(xbt, 1);
826 static int connect_ring(struct backend_info *be)
828 struct xenbus_device *dev = be->dev;
829 unsigned int ring_ref[XENBUS_MAX_RING_PAGES];
830 unsigned int evtchn, nr_grefs, ring_page_order;
831 unsigned int pers_grants;
832 char protocol[64] = "";
833 struct pending_req *req, *n;
836 pr_debug("%s %s\n", __func__, dev->otherend);
838 err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u",
842 xenbus_dev_fatal(dev, err, "reading %s/event-channel",
846 pr_info("event-channel %u\n", evtchn);
848 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
851 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref",
855 xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
860 pr_info("%s:using single page: ring-ref %d\n", dev->otherend,
865 if (ring_page_order > xen_blkif_max_ring_order) {
867 xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
868 dev->otherend, ring_page_order,
869 xen_blkif_max_ring_order);
873 nr_grefs = 1 << ring_page_order;
874 for (i = 0; i < nr_grefs; i++) {
875 char ring_ref_name[RINGREF_NAME_LEN];
877 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
878 err = xenbus_scanf(XBT_NIL, dev->otherend, ring_ref_name,
882 xenbus_dev_fatal(dev, err, "reading %s/%s",
883 dev->otherend, ring_ref_name);
886 pr_info("ring-ref%u: %u\n", i, ring_ref[i]);
890 be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
891 err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
892 "%63s", protocol, NULL);
894 strcpy(protocol, "unspecified, assuming default");
895 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
896 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
897 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
898 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
899 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
900 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
902 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
905 err = xenbus_gather(XBT_NIL, dev->otherend,
906 "feature-persistent", "%u",
911 be->blkif->vbd.feature_gnt_persistent = pers_grants;
912 be->blkif->vbd.overflow_max_grants = 0;
913 be->blkif->nr_ring_pages = nr_grefs;
915 pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n",
916 nr_grefs, evtchn, be->blkif->blk_protocol, protocol,
917 pers_grants ? "persistent grants" : "");
919 for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
920 req = kzalloc(sizeof(*req), GFP_KERNEL);
923 list_add_tail(&req->free_list, &be->blkif->pending_free);
924 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
925 req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL);
926 if (!req->segments[j])
929 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
930 req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
932 if (!req->indirect_pages[j])
937 /* Map the shared frame, irq etc. */
938 err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn);
940 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
947 list_for_each_entry_safe(req, n, &be->blkif->pending_free, free_list) {
948 list_del(&req->free_list);
949 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
950 if (!req->segments[j])
952 kfree(req->segments[j]);
954 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
955 if (!req->indirect_pages[j])
957 kfree(req->indirect_pages[j]);
964 static const struct xenbus_device_id xen_blkbk_ids[] = {
969 static struct xenbus_driver xen_blkbk_driver = {
970 .ids = xen_blkbk_ids,
971 .probe = xen_blkbk_probe,
972 .remove = xen_blkbk_remove,
973 .otherend_changed = frontend_changed
976 int xen_blkif_xenbus_init(void)
978 return xenbus_register_backend(&xen_blkbk_driver);