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.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 #include <linux/module.h>
22 #include <linux/kthread.h>
26 #define DPRINTK(fmt, args...) \
27 pr_debug("blkback/xenbus (%s:%d) " fmt ".\n", \
28 __func__, __LINE__, ##args)
31 struct xenbus_device *dev;
32 struct blkif_st *blkif;
33 struct xenbus_watch backend_watch;
39 static void connect(struct backend_info *);
40 static int connect_ring(struct backend_info *);
41 static void backend_changed(struct xenbus_watch *, const char **,
44 struct xenbus_device *blkback_xenbus(struct backend_info *be)
49 static int blkback_name(struct blkif_st *blkif, char *buf)
51 char *devpath, *devname;
52 struct xenbus_device *dev = blkif->be->dev;
54 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
56 return PTR_ERR(devpath);
58 devname = strstr(devpath, "/dev/");
60 devname += strlen("/dev/");
64 snprintf(buf, TASK_COMM_LEN, "blkback.%d.%s", blkif->domid, devname);
70 static void update_blkif_status(struct blkif_st *blkif)
73 char name[TASK_COMM_LEN];
75 /* Not ready to connect? */
76 if (!blkif->irq || !blkif->vbd.bdev)
79 /* Already connected? */
80 if (blkif->be->dev->state == XenbusStateConnected)
83 /* Attempt to connect: exit if we fail to. */
85 if (blkif->be->dev->state != XenbusStateConnected)
88 err = blkback_name(blkif, name);
90 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
94 err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
96 xenbus_dev_error(blkif->be->dev, err, "block flush");
99 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
101 blkif->xenblkd = kthread_run(blkif_schedule, blkif, name);
102 if (IS_ERR(blkif->xenblkd)) {
103 err = PTR_ERR(blkif->xenblkd);
104 blkif->xenblkd = NULL;
105 xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
111 * sysfs interface for VBD I/O requests
114 #define VBD_SHOW(name, format, args...) \
115 static ssize_t show_##name(struct device *_dev, \
116 struct device_attribute *attr, \
119 struct xenbus_device *dev = to_xenbus_device(_dev); \
120 struct backend_info *be = dev_get_drvdata(&dev->dev); \
122 return sprintf(buf, format, ##args); \
124 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
126 VBD_SHOW(oo_req, "%d\n", be->blkif->st_oo_req);
127 VBD_SHOW(rd_req, "%d\n", be->blkif->st_rd_req);
128 VBD_SHOW(wr_req, "%d\n", be->blkif->st_wr_req);
129 VBD_SHOW(br_req, "%d\n", be->blkif->st_br_req);
130 VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect);
131 VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect);
133 static struct attribute *vbdstat_attrs[] = {
134 &dev_attr_oo_req.attr,
135 &dev_attr_rd_req.attr,
136 &dev_attr_wr_req.attr,
137 &dev_attr_br_req.attr,
138 &dev_attr_rd_sect.attr,
139 &dev_attr_wr_sect.attr,
143 static struct attribute_group vbdstat_group = {
144 .name = "statistics",
145 .attrs = vbdstat_attrs,
148 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
149 VBD_SHOW(mode, "%s\n", be->mode);
151 int xenvbd_sysfs_addif(struct xenbus_device *dev)
155 error = device_create_file(&dev->dev, &dev_attr_physical_device);
159 error = device_create_file(&dev->dev, &dev_attr_mode);
163 error = sysfs_create_group(&dev->dev.kobj, &vbdstat_group);
169 fail3: sysfs_remove_group(&dev->dev.kobj, &vbdstat_group);
170 fail2: device_remove_file(&dev->dev, &dev_attr_mode);
171 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device);
175 void xenvbd_sysfs_delif(struct xenbus_device *dev)
177 sysfs_remove_group(&dev->dev.kobj, &vbdstat_group);
178 device_remove_file(&dev->dev, &dev_attr_mode);
179 device_remove_file(&dev->dev, &dev_attr_physical_device);
182 static int blkback_remove(struct xenbus_device *dev)
184 struct backend_info *be = dev_get_drvdata(&dev->dev);
188 if (be->major || be->minor)
189 xenvbd_sysfs_delif(dev);
191 if (be->backend_watch.node) {
192 unregister_xenbus_watch(&be->backend_watch);
193 kfree(be->backend_watch.node);
194 be->backend_watch.node = NULL;
198 blkif_disconnect(be->blkif);
199 vbd_free(&be->blkif->vbd);
200 blkif_free(be->blkif);
205 dev_set_drvdata(&dev->dev, NULL);
209 int blkback_barrier(struct xenbus_transaction xbt,
210 struct backend_info *be, int state)
212 struct xenbus_device *dev = be->dev;
215 err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
218 xenbus_dev_fatal(dev, err, "writing feature-barrier");
224 * Entry point to this code when a new device is created. Allocate the basic
225 * structures, and watch the store waiting for the hotplug scripts to tell us
226 * the device's physical major and minor numbers. Switch to InitWait.
228 static int blkback_probe(struct xenbus_device *dev,
229 const struct xenbus_device_id *id)
232 struct backend_info *be = kzalloc(sizeof(struct backend_info),
235 xenbus_dev_fatal(dev, -ENOMEM,
236 "allocating backend structure");
240 dev_set_drvdata(&dev->dev, be);
242 be->blkif = blkif_alloc(dev->otherend_id);
243 if (IS_ERR(be->blkif)) {
244 err = PTR_ERR(be->blkif);
246 xenbus_dev_fatal(dev, err, "creating block interface");
250 /* setup back pointer */
253 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
254 "%s/%s", dev->nodename, "physical-device");
258 err = xenbus_switch_state(dev, XenbusStateInitWait);
272 * Callback received when the hotplug scripts have placed the physical-device
273 * node. Read it and the mode node, and create a vbd. If the frontend is
276 static void backend_changed(struct xenbus_watch *watch,
277 const char **vec, unsigned int len)
282 struct backend_info *be
283 = container_of(watch, struct backend_info, backend_watch);
284 struct xenbus_device *dev = be->dev;
290 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
292 if (XENBUS_EXIST_ERR(err)) {
293 /* Since this watch will fire once immediately after it is
294 registered, we expect this. Ignore it, and wait for the
299 xenbus_dev_fatal(dev, err, "reading physical-device");
303 if ((be->major || be->minor) &&
304 ((be->major != major) || (be->minor != minor))) {
306 "blkback: changing physical device (from %x:%x to "
307 "%x:%x) not supported.\n", be->major, be->minor,
312 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
313 if (IS_ERR(be->mode)) {
314 err = PTR_ERR(be->mode);
316 xenbus_dev_fatal(dev, err, "reading mode");
320 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
321 if (!IS_ERR(device_type)) {
322 cdrom = strcmp(device_type, "cdrom") == 0;
326 if (be->major == 0 && be->minor == 0) {
327 /* Front end dir is a number, which is used as the handle. */
329 char *p = strrchr(dev->otherend, '/') + 1;
331 err = strict_strtoul(p, 0, &handle);
338 err = vbd_create(be->blkif, handle, major, minor,
339 (NULL == strchr(be->mode, 'w')), cdrom);
341 be->major = be->minor = 0;
342 xenbus_dev_fatal(dev, err, "creating vbd structure");
346 err = xenvbd_sysfs_addif(dev);
348 vbd_free(&be->blkif->vbd);
349 be->major = be->minor = 0;
350 xenbus_dev_fatal(dev, err, "creating sysfs entries");
354 /* We're potentially connected now */
355 update_blkif_status(be->blkif);
361 * Callback received when the frontend's state changes.
363 static void frontend_changed(struct xenbus_device *dev,
364 enum xenbus_state frontend_state)
366 struct backend_info *be = dev_get_drvdata(&dev->dev);
369 DPRINTK("%s", xenbus_strstate(frontend_state));
371 switch (frontend_state) {
372 case XenbusStateInitialising:
373 if (dev->state == XenbusStateClosed) {
374 printk(KERN_INFO "%s: %s: prepare for reconnect\n",
375 __func__, dev->nodename);
376 xenbus_switch_state(dev, XenbusStateInitWait);
380 case XenbusStateInitialised:
381 case XenbusStateConnected:
382 /* Ensure we connect even when two watches fire in
383 close successsion and we miss the intermediate value
384 of frontend_state. */
385 if (dev->state == XenbusStateConnected)
388 /* Enforce precondition before potential leak point.
389 * blkif_disconnect() is idempotent.
391 blkif_disconnect(be->blkif);
393 err = connect_ring(be);
396 update_blkif_status(be->blkif);
399 case XenbusStateClosing:
400 blkif_disconnect(be->blkif);
401 xenbus_switch_state(dev, XenbusStateClosing);
404 case XenbusStateClosed:
405 xenbus_switch_state(dev, XenbusStateClosed);
406 if (xenbus_dev_is_online(dev))
408 /* fall through if not online */
409 case XenbusStateUnknown:
410 /* implies blkif_disconnect() via blkback_remove() */
411 device_unregister(&dev->dev);
415 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
422 /* ** Connection ** */
426 * Write the physical details regarding the block device to the store, and
427 * switch to Connected state.
429 static void connect(struct backend_info *be)
431 struct xenbus_transaction xbt;
433 struct xenbus_device *dev = be->dev;
435 DPRINTK("%s", dev->otherend);
437 /* Supply the information about the device the frontend needs */
439 err = xenbus_transaction_start(&xbt);
441 xenbus_dev_fatal(dev, err, "starting transaction");
445 err = blkback_barrier(xbt, be, 1);
449 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
450 vbd_size(&be->blkif->vbd));
452 xenbus_dev_fatal(dev, err, "writing %s/sectors",
457 /* FIXME: use a typename instead */
458 err = xenbus_printf(xbt, dev->nodename, "info", "%u",
459 vbd_info(&be->blkif->vbd));
461 xenbus_dev_fatal(dev, err, "writing %s/info",
465 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
466 vbd_secsize(&be->blkif->vbd));
468 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
473 err = xenbus_transaction_end(xbt, 0);
477 xenbus_dev_fatal(dev, err, "ending transaction");
479 err = xenbus_switch_state(dev, XenbusStateConnected);
481 xenbus_dev_fatal(dev, err, "switching to Connected state",
486 xenbus_transaction_end(xbt, 1);
490 static int connect_ring(struct backend_info *be)
492 struct xenbus_device *dev = be->dev;
493 unsigned long ring_ref;
495 char protocol[64] = "";
498 DPRINTK("%s", dev->otherend);
500 err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu",
501 &ring_ref, "event-channel", "%u", &evtchn, NULL);
503 xenbus_dev_fatal(dev, err,
504 "reading %s/ring-ref and event-channel",
509 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
510 err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
511 "%63s", protocol, NULL);
513 strcpy(protocol, "unspecified, assuming native");
514 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
515 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
516 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
517 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
518 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
519 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
521 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
525 "blkback: ring-ref %ld, event-channel %d, protocol %d (%s)\n",
526 ring_ref, evtchn, be->blkif->blk_protocol, protocol);
528 /* Map the shared frame, irq etc. */
529 err = blkif_map(be->blkif, ring_ref, evtchn);
531 xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u",
540 /* ** Driver Registration ** */
543 static const struct xenbus_device_id blkback_ids[] = {
549 static struct xenbus_driver blkback = {
551 .owner = THIS_MODULE,
553 .probe = blkback_probe,
554 .remove = blkback_remove,
555 .otherend_changed = frontend_changed
559 int blkif_xenbus_init(void)
561 return xenbus_register_backend(&blkback);