blob: 3ca643cafccdc6be26bb24532db09ccddeff12f9 [file] [log] [blame]
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -07001/*
2 * blkfront.c
3 *
4 * XenLinux virtual block device driver.
5 *
6 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
7 * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
8 * Copyright (c) 2004, Christian Limpach
9 * Copyright (c) 2004, Andrew Warfield
10 * Copyright (c) 2005, Christopher Clark
11 * Copyright (c) 2005, XenSource Ltd
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License version 2
15 * as published by the Free Software Foundation; or, when distributed
16 * separately from the Linux kernel or incorporated into other
17 * software packages, subject to the following license:
18 *
19 * Permission is hereby granted, free of charge, to any person obtaining a copy
20 * of this source file (the "Software"), to deal in the Software without
21 * restriction, including without limitation the rights to use, copy, modify,
22 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
23 * and to permit persons to whom the Software is furnished to do so, subject to
24 * the following conditions:
25 *
26 * The above copyright notice and this permission notice shall be included in
27 * all copies or substantial portions of the Software.
28 *
29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
35 * IN THE SOFTWARE.
36 */
37
38#include <linux/interrupt.h>
39#include <linux/blkdev.h>
Ian Campbell597592d2008-02-21 13:03:45 -080040#include <linux/hdreg.h>
Christian Limpach440a01a2008-06-17 10:47:08 +020041#include <linux/cdrom.h>
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -070042#include <linux/module.h>
43
44#include <xen/xenbus.h>
45#include <xen/grant_table.h>
46#include <xen/events.h>
47#include <xen/page.h>
48
49#include <xen/interface/grant_table.h>
50#include <xen/interface/io/blkif.h>
Markus Armbruster3e334232008-04-02 10:54:02 -070051#include <xen/interface/io/protocols.h>
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -070052
53#include <asm/xen/hypervisor.h>
54
55enum blkif_state {
56 BLKIF_STATE_DISCONNECTED,
57 BLKIF_STATE_CONNECTED,
58 BLKIF_STATE_SUSPENDED,
59};
60
61struct blk_shadow {
62 struct blkif_request req;
63 unsigned long request;
64 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
65};
66
67static struct block_device_operations xlvbd_block_fops;
68
69#define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
70
71/*
72 * We have one of these per vbd, whether ide, scsi or 'other'. They
73 * hang in private_data off the gendisk structure. We may end up
74 * putting all kinds of interesting stuff here :-)
75 */
76struct blkfront_info
77{
78 struct xenbus_device *xbdev;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -070079 struct gendisk *gd;
80 int vdevice;
81 blkif_vdev_t handle;
82 enum blkif_state connected;
83 int ring_ref;
84 struct blkif_front_ring ring;
85 unsigned int evtchn, irq;
86 struct request_queue *rq;
87 struct work_struct work;
88 struct gnttab_free_callback callback;
89 struct blk_shadow shadow[BLK_RING_SIZE];
90 unsigned long shadow_free;
91 int feature_barrier;
Christian Limpach1d78d702008-04-02 10:54:04 -070092 int is_ready;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -070093
94 /**
95 * The number of people holding this device open. We won't allow a
96 * hot-unplug unless this is 0.
97 */
98 int users;
99};
100
101static DEFINE_SPINLOCK(blkif_io_lock);
102
103#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
104 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
105#define GRANT_INVALID_REF 0
106
107#define PARTS_PER_DISK 16
108
109#define BLKIF_MAJOR(dev) ((dev)>>8)
110#define BLKIF_MINOR(dev) ((dev) & 0xff)
111
112#define DEV_NAME "xvd" /* name in /dev */
113
114/* Information about our VBDs. */
115#define MAX_VBDS 64
116static LIST_HEAD(vbds_list);
117
118static int get_id_from_freelist(struct blkfront_info *info)
119{
120 unsigned long free = info->shadow_free;
121 BUG_ON(free > BLK_RING_SIZE);
122 info->shadow_free = info->shadow[free].req.id;
123 info->shadow[free].req.id = 0x0fffffee; /* debug */
124 return free;
125}
126
127static void add_id_to_freelist(struct blkfront_info *info,
128 unsigned long id)
129{
130 info->shadow[id].req.id = info->shadow_free;
131 info->shadow[id].request = 0;
132 info->shadow_free = id;
133}
134
135static void blkif_restart_queue_callback(void *arg)
136{
137 struct blkfront_info *info = (struct blkfront_info *)arg;
138 schedule_work(&info->work);
139}
140
Harvey Harrisonafe42d72008-04-29 00:59:47 -0700141static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
Ian Campbell597592d2008-02-21 13:03:45 -0800142{
143 /* We don't have real geometry info, but let's at least return
144 values consistent with the size of the device */
145 sector_t nsect = get_capacity(bd->bd_disk);
146 sector_t cylinders = nsect;
147
148 hg->heads = 0xff;
149 hg->sectors = 0x3f;
150 sector_div(cylinders, hg->heads * hg->sectors);
151 hg->cylinders = cylinders;
152 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
153 hg->cylinders = 0xffff;
154 return 0;
155}
156
Adrian Bunk62aa0052008-08-04 11:59:05 +0200157static int blkif_ioctl(struct inode *inode, struct file *filep,
158 unsigned command, unsigned long argument)
Christian Limpach440a01a2008-06-17 10:47:08 +0200159{
160 struct blkfront_info *info =
161 inode->i_bdev->bd_disk->private_data;
162 int i;
163
164 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
165 command, (long)argument);
166
167 switch (command) {
168 case CDROMMULTISESSION:
169 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
170 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
171 if (put_user(0, (char __user *)(argument + i)))
172 return -EFAULT;
173 return 0;
174
175 case CDROM_GET_CAPABILITY: {
176 struct gendisk *gd = info->gd;
177 if (gd->flags & GENHD_FL_CD)
178 return 0;
179 return -EINVAL;
180 }
181
182 default:
183 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
184 command);*/
185 return -EINVAL; /* same return as native Linux */
186 }
187
188 return 0;
189}
190
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700191/*
192 * blkif_queue_request
193 *
194 * request block io
195 *
196 * id: for guest use only.
197 * operation: BLKIF_OP_{READ,WRITE,PROBE}
198 * buffer: buffer to read/write into. this should be a
199 * virtual address in the guest os.
200 */
201static int blkif_queue_request(struct request *req)
202{
203 struct blkfront_info *info = req->rq_disk->private_data;
204 unsigned long buffer_mfn;
205 struct blkif_request *ring_req;
NeilBrown5705f702007-09-25 12:35:59 +0200206 struct req_iterator iter;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700207 struct bio_vec *bvec;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700208 unsigned long id;
209 unsigned int fsect, lsect;
210 int ref;
211 grant_ref_t gref_head;
212
213 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
214 return 1;
215
216 if (gnttab_alloc_grant_references(
217 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
218 gnttab_request_free_callback(
219 &info->callback,
220 blkif_restart_queue_callback,
221 info,
222 BLKIF_MAX_SEGMENTS_PER_REQUEST);
223 return 1;
224 }
225
226 /* Fill out a communications ring structure. */
227 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
228 id = get_id_from_freelist(info);
229 info->shadow[id].request = (unsigned long)req;
230
231 ring_req->id = id;
232 ring_req->sector_number = (blkif_sector_t)req->sector;
233 ring_req->handle = info->handle;
234
235 ring_req->operation = rq_data_dir(req) ?
236 BLKIF_OP_WRITE : BLKIF_OP_READ;
237 if (blk_barrier_rq(req))
238 ring_req->operation = BLKIF_OP_WRITE_BARRIER;
239
240 ring_req->nr_segments = 0;
NeilBrown5705f702007-09-25 12:35:59 +0200241 rq_for_each_segment(bvec, req, iter) {
Jens Axboe6c92e692007-08-16 13:43:12 +0200242 BUG_ON(ring_req->nr_segments == BLKIF_MAX_SEGMENTS_PER_REQUEST);
243 buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page));
244 fsect = bvec->bv_offset >> 9;
245 lsect = fsect + (bvec->bv_len >> 9) - 1;
246 /* install a grant reference. */
247 ref = gnttab_claim_grant_reference(&gref_head);
248 BUG_ON(ref == -ENOSPC);
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700249
Jens Axboe6c92e692007-08-16 13:43:12 +0200250 gnttab_grant_foreign_access_ref(
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700251 ref,
252 info->xbdev->otherend_id,
253 buffer_mfn,
254 rq_data_dir(req) );
255
Jens Axboe6c92e692007-08-16 13:43:12 +0200256 info->shadow[id].frame[ring_req->nr_segments] =
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700257 mfn_to_pfn(buffer_mfn);
258
Jens Axboe6c92e692007-08-16 13:43:12 +0200259 ring_req->seg[ring_req->nr_segments] =
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700260 (struct blkif_request_segment) {
261 .gref = ref,
262 .first_sect = fsect,
263 .last_sect = lsect };
264
Jens Axboe6c92e692007-08-16 13:43:12 +0200265 ring_req->nr_segments++;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700266 }
267
268 info->ring.req_prod_pvt++;
269
270 /* Keep a private copy so we can reissue requests when recovering. */
271 info->shadow[id].req = *ring_req;
272
273 gnttab_free_grant_references(gref_head);
274
275 return 0;
276}
277
278
279static inline void flush_requests(struct blkfront_info *info)
280{
281 int notify;
282
283 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
284
285 if (notify)
286 notify_remote_via_irq(info->irq);
287}
288
289/*
290 * do_blkif_request
291 * read a block; request is in a request queue
292 */
Jens Axboe165125e2007-07-24 09:28:11 +0200293static void do_blkif_request(struct request_queue *rq)
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700294{
295 struct blkfront_info *info = NULL;
296 struct request *req;
297 int queued;
298
299 pr_debug("Entered do_blkif_request\n");
300
301 queued = 0;
302
303 while ((req = elv_next_request(rq)) != NULL) {
304 info = req->rq_disk->private_data;
305 if (!blk_fs_request(req)) {
306 end_request(req, 0);
307 continue;
308 }
309
310 if (RING_FULL(&info->ring))
311 goto wait;
312
313 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
314 "(%u/%li) buffer:%p [%s]\n",
315 req, req->cmd, (unsigned long)req->sector,
316 req->current_nr_sectors,
317 req->nr_sectors, req->buffer,
318 rq_data_dir(req) ? "write" : "read");
319
320
321 blkdev_dequeue_request(req);
322 if (blkif_queue_request(req)) {
323 blk_requeue_request(rq, req);
324wait:
325 /* Avoid pointless unplugs. */
326 blk_stop_queue(rq);
327 break;
328 }
329
330 queued++;
331 }
332
333 if (queued != 0)
334 flush_requests(info);
335}
336
337static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
338{
Jens Axboe165125e2007-07-24 09:28:11 +0200339 struct request_queue *rq;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700340
341 rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
342 if (rq == NULL)
343 return -1;
344
345 elevator_init(rq, "noop");
346
347 /* Hard sector size and max sectors impersonate the equiv. hardware. */
348 blk_queue_hardsect_size(rq, sector_size);
349 blk_queue_max_sectors(rq, 512);
350
351 /* Each segment in a request is up to an aligned page in size. */
352 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
353 blk_queue_max_segment_size(rq, PAGE_SIZE);
354
355 /* Ensure a merged request will fit in a single I/O ring slot. */
356 blk_queue_max_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
357 blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
358
359 /* Make sure buffer addresses are sector-aligned. */
360 blk_queue_dma_alignment(rq, 511);
361
Ian Campbell1c91fe12008-06-17 10:47:08 +0200362 /* Make sure we don't use bounce buffers. */
363 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
364
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700365 gd->queue = rq;
366
367 return 0;
368}
369
370
371static int xlvbd_barrier(struct blkfront_info *info)
372{
373 int err;
374
375 err = blk_queue_ordered(info->rq,
376 info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE,
377 NULL);
378
379 if (err)
380 return err;
381
382 printk(KERN_INFO "blkfront: %s: barriers %s\n",
383 info->gd->disk_name,
384 info->feature_barrier ? "enabled" : "disabled");
385 return 0;
386}
387
388
389static int xlvbd_alloc_gendisk(int minor, blkif_sector_t capacity,
390 int vdevice, u16 vdisk_info, u16 sector_size,
391 struct blkfront_info *info)
392{
393 struct gendisk *gd;
394 int nr_minors = 1;
395 int err = -ENODEV;
396
397 BUG_ON(info->gd != NULL);
398 BUG_ON(info->rq != NULL);
399
400 if ((minor % PARTS_PER_DISK) == 0)
401 nr_minors = PARTS_PER_DISK;
402
403 gd = alloc_disk(nr_minors);
404 if (gd == NULL)
405 goto out;
406
407 if (nr_minors > 1)
408 sprintf(gd->disk_name, "%s%c", DEV_NAME,
409 'a' + minor / PARTS_PER_DISK);
410 else
411 sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
412 'a' + minor / PARTS_PER_DISK,
413 minor % PARTS_PER_DISK);
414
415 gd->major = XENVBD_MAJOR;
416 gd->first_minor = minor;
417 gd->fops = &xlvbd_block_fops;
418 gd->private_data = info;
419 gd->driverfs_dev = &(info->xbdev->dev);
420 set_capacity(gd, capacity);
421
422 if (xlvbd_init_blk_queue(gd, sector_size)) {
423 del_gendisk(gd);
424 goto out;
425 }
426
427 info->rq = gd->queue;
428 info->gd = gd;
429
430 if (info->feature_barrier)
431 xlvbd_barrier(info);
432
433 if (vdisk_info & VDISK_READONLY)
434 set_disk_ro(gd, 1);
435
436 if (vdisk_info & VDISK_REMOVABLE)
437 gd->flags |= GENHD_FL_REMOVABLE;
438
439 if (vdisk_info & VDISK_CDROM)
440 gd->flags |= GENHD_FL_CD;
441
442 return 0;
443
444 out:
445 return err;
446}
447
448static void kick_pending_request_queues(struct blkfront_info *info)
449{
450 if (!RING_FULL(&info->ring)) {
451 /* Re-enable calldowns. */
452 blk_start_queue(info->rq);
453 /* Kick things off immediately. */
454 do_blkif_request(info->rq);
455 }
456}
457
458static void blkif_restart_queue(struct work_struct *work)
459{
460 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
461
462 spin_lock_irq(&blkif_io_lock);
463 if (info->connected == BLKIF_STATE_CONNECTED)
464 kick_pending_request_queues(info);
465 spin_unlock_irq(&blkif_io_lock);
466}
467
468static void blkif_free(struct blkfront_info *info, int suspend)
469{
470 /* Prevent new requests being issued until we fix things up. */
471 spin_lock_irq(&blkif_io_lock);
472 info->connected = suspend ?
473 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
474 /* No more blkif_request(). */
475 if (info->rq)
476 blk_stop_queue(info->rq);
477 /* No more gnttab callback work. */
478 gnttab_cancel_free_callback(&info->callback);
479 spin_unlock_irq(&blkif_io_lock);
480
481 /* Flush gnttab callback work. Must be done with no locks held. */
482 flush_scheduled_work();
483
484 /* Free resources associated with old device channel. */
485 if (info->ring_ref != GRANT_INVALID_REF) {
486 gnttab_end_foreign_access(info->ring_ref, 0,
487 (unsigned long)info->ring.sring);
488 info->ring_ref = GRANT_INVALID_REF;
489 info->ring.sring = NULL;
490 }
491 if (info->irq)
492 unbind_from_irqhandler(info->irq, info);
493 info->evtchn = info->irq = 0;
494
495}
496
497static void blkif_completion(struct blk_shadow *s)
498{
499 int i;
500 for (i = 0; i < s->req.nr_segments; i++)
501 gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
502}
503
504static irqreturn_t blkif_interrupt(int irq, void *dev_id)
505{
506 struct request *req;
507 struct blkif_response *bret;
508 RING_IDX i, rp;
509 unsigned long flags;
510 struct blkfront_info *info = (struct blkfront_info *)dev_id;
Kiyoshi Uedaf530f0362007-12-11 17:47:36 -0500511 int error;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700512
513 spin_lock_irqsave(&blkif_io_lock, flags);
514
515 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
516 spin_unlock_irqrestore(&blkif_io_lock, flags);
517 return IRQ_HANDLED;
518 }
519
520 again:
521 rp = info->ring.sring->rsp_prod;
522 rmb(); /* Ensure we see queued responses up to 'rp'. */
523
524 for (i = info->ring.rsp_cons; i != rp; i++) {
525 unsigned long id;
526 int ret;
527
528 bret = RING_GET_RESPONSE(&info->ring, i);
529 id = bret->id;
530 req = (struct request *)info->shadow[id].request;
531
532 blkif_completion(&info->shadow[id]);
533
534 add_id_to_freelist(info, id);
535
Kiyoshi Uedaf530f0362007-12-11 17:47:36 -0500536 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700537 switch (bret->operation) {
538 case BLKIF_OP_WRITE_BARRIER:
539 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
540 printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
541 info->gd->disk_name);
Kiyoshi Uedaf530f0362007-12-11 17:47:36 -0500542 error = -EOPNOTSUPP;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700543 info->feature_barrier = 0;
544 xlvbd_barrier(info);
545 }
546 /* fall through */
547 case BLKIF_OP_READ:
548 case BLKIF_OP_WRITE:
549 if (unlikely(bret->status != BLKIF_RSP_OKAY))
550 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
551 "request: %x\n", bret->status);
552
Kiyoshi Uedaf530f0362007-12-11 17:47:36 -0500553 ret = __blk_end_request(req, error, blk_rq_bytes(req));
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700554 BUG_ON(ret);
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700555 break;
556 default:
557 BUG();
558 }
559 }
560
561 info->ring.rsp_cons = i;
562
563 if (i != info->ring.req_prod_pvt) {
564 int more_to_do;
565 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
566 if (more_to_do)
567 goto again;
568 } else
569 info->ring.sring->rsp_event = i + 1;
570
571 kick_pending_request_queues(info);
572
573 spin_unlock_irqrestore(&blkif_io_lock, flags);
574
575 return IRQ_HANDLED;
576}
577
578
579static int setup_blkring(struct xenbus_device *dev,
580 struct blkfront_info *info)
581{
582 struct blkif_sring *sring;
583 int err;
584
585 info->ring_ref = GRANT_INVALID_REF;
586
Ian Campbella144ff02008-06-17 10:47:08 +0200587 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700588 if (!sring) {
589 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
590 return -ENOMEM;
591 }
592 SHARED_RING_INIT(sring);
593 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
594
595 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
596 if (err < 0) {
597 free_page((unsigned long)sring);
598 info->ring.sring = NULL;
599 goto fail;
600 }
601 info->ring_ref = err;
602
603 err = xenbus_alloc_evtchn(dev, &info->evtchn);
604 if (err)
605 goto fail;
606
607 err = bind_evtchn_to_irqhandler(info->evtchn,
608 blkif_interrupt,
609 IRQF_SAMPLE_RANDOM, "blkif", info);
610 if (err <= 0) {
611 xenbus_dev_fatal(dev, err,
612 "bind_evtchn_to_irqhandler failed");
613 goto fail;
614 }
615 info->irq = err;
616
617 return 0;
618fail:
619 blkif_free(info, 0);
620 return err;
621}
622
623
624/* Common code used when first setting up, and when resuming. */
625static int talk_to_backend(struct xenbus_device *dev,
626 struct blkfront_info *info)
627{
628 const char *message = NULL;
629 struct xenbus_transaction xbt;
630 int err;
631
632 /* Create shared ring, alloc event channel. */
633 err = setup_blkring(dev, info);
634 if (err)
635 goto out;
636
637again:
638 err = xenbus_transaction_start(&xbt);
639 if (err) {
640 xenbus_dev_fatal(dev, err, "starting transaction");
641 goto destroy_blkring;
642 }
643
644 err = xenbus_printf(xbt, dev->nodename,
645 "ring-ref", "%u", info->ring_ref);
646 if (err) {
647 message = "writing ring-ref";
648 goto abort_transaction;
649 }
650 err = xenbus_printf(xbt, dev->nodename,
651 "event-channel", "%u", info->evtchn);
652 if (err) {
653 message = "writing event-channel";
654 goto abort_transaction;
655 }
Markus Armbruster3e334232008-04-02 10:54:02 -0700656 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
657 XEN_IO_PROTO_ABI_NATIVE);
658 if (err) {
659 message = "writing protocol";
660 goto abort_transaction;
661 }
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700662
663 err = xenbus_transaction_end(xbt, 0);
664 if (err) {
665 if (err == -EAGAIN)
666 goto again;
667 xenbus_dev_fatal(dev, err, "completing transaction");
668 goto destroy_blkring;
669 }
670
671 xenbus_switch_state(dev, XenbusStateInitialised);
672
673 return 0;
674
675 abort_transaction:
676 xenbus_transaction_end(xbt, 1);
677 if (message)
678 xenbus_dev_fatal(dev, err, "%s", message);
679 destroy_blkring:
680 blkif_free(info, 0);
681 out:
682 return err;
683}
684
685
686/**
687 * Entry point to this code when a new device is created. Allocate the basic
688 * structures and the ring buffer for communication with the backend, and
689 * inform the backend of the appropriate details for those. Switch to
690 * Initialised state.
691 */
692static int blkfront_probe(struct xenbus_device *dev,
693 const struct xenbus_device_id *id)
694{
695 int err, vdevice, i;
696 struct blkfront_info *info;
697
698 /* FIXME: Use dynamic device id if this is not set. */
699 err = xenbus_scanf(XBT_NIL, dev->nodename,
700 "virtual-device", "%i", &vdevice);
701 if (err != 1) {
702 xenbus_dev_fatal(dev, err, "reading virtual-device");
703 return err;
704 }
705
706 info = kzalloc(sizeof(*info), GFP_KERNEL);
707 if (!info) {
708 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
709 return -ENOMEM;
710 }
711
712 info->xbdev = dev;
713 info->vdevice = vdevice;
714 info->connected = BLKIF_STATE_DISCONNECTED;
715 INIT_WORK(&info->work, blkif_restart_queue);
716
717 for (i = 0; i < BLK_RING_SIZE; i++)
718 info->shadow[i].req.id = i+1;
719 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
720
721 /* Front end dir is a number, which is used as the id. */
722 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
723 dev->dev.driver_data = info;
724
725 err = talk_to_backend(dev, info);
726 if (err) {
727 kfree(info);
728 dev->dev.driver_data = NULL;
729 return err;
730 }
731
732 return 0;
733}
734
735
736static int blkif_recover(struct blkfront_info *info)
737{
738 int i;
739 struct blkif_request *req;
740 struct blk_shadow *copy;
741 int j;
742
743 /* Stage 1: Make a safe copy of the shadow state. */
Ian Campbella144ff02008-06-17 10:47:08 +0200744 copy = kmalloc(sizeof(info->shadow),
745 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700746 if (!copy)
747 return -ENOMEM;
748 memcpy(copy, info->shadow, sizeof(info->shadow));
749
750 /* Stage 2: Set up free list. */
751 memset(&info->shadow, 0, sizeof(info->shadow));
752 for (i = 0; i < BLK_RING_SIZE; i++)
753 info->shadow[i].req.id = i+1;
754 info->shadow_free = info->ring.req_prod_pvt;
755 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
756
757 /* Stage 3: Find pending requests and requeue them. */
758 for (i = 0; i < BLK_RING_SIZE; i++) {
759 /* Not in use? */
760 if (copy[i].request == 0)
761 continue;
762
763 /* Grab a request slot and copy shadow state into it. */
764 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
765 *req = copy[i].req;
766
767 /* We get a new request id, and must reset the shadow state. */
768 req->id = get_id_from_freelist(info);
769 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
770
771 /* Rewrite any grant references invalidated by susp/resume. */
772 for (j = 0; j < req->nr_segments; j++)
773 gnttab_grant_foreign_access_ref(
774 req->seg[j].gref,
775 info->xbdev->otherend_id,
776 pfn_to_mfn(info->shadow[req->id].frame[j]),
777 rq_data_dir(
778 (struct request *)
779 info->shadow[req->id].request));
780 info->shadow[req->id].req = *req;
781
782 info->ring.req_prod_pvt++;
783 }
784
785 kfree(copy);
786
787 xenbus_switch_state(info->xbdev, XenbusStateConnected);
788
789 spin_lock_irq(&blkif_io_lock);
790
791 /* Now safe for us to use the shared ring */
792 info->connected = BLKIF_STATE_CONNECTED;
793
794 /* Send off requeued requests */
795 flush_requests(info);
796
797 /* Kick any other new requests queued since we resumed */
798 kick_pending_request_queues(info);
799
800 spin_unlock_irq(&blkif_io_lock);
801
802 return 0;
803}
804
805/**
806 * We are reconnecting to the backend, due to a suspend/resume, or a backend
807 * driver restart. We tear down our blkif structure and recreate it, but
808 * leave the device-layer structures intact so that this is transparent to the
809 * rest of the kernel.
810 */
811static int blkfront_resume(struct xenbus_device *dev)
812{
813 struct blkfront_info *info = dev->dev.driver_data;
814 int err;
815
816 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
817
818 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
819
820 err = talk_to_backend(dev, info);
821 if (info->connected == BLKIF_STATE_SUSPENDED && !err)
822 err = blkif_recover(info);
823
824 return err;
825}
826
827
828/*
829 * Invoked when the backend is finally 'ready' (and has told produced
830 * the details about the physical device - #sectors, size, etc).
831 */
832static void blkfront_connect(struct blkfront_info *info)
833{
834 unsigned long long sectors;
835 unsigned long sector_size;
836 unsigned int binfo;
837 int err;
838
839 if ((info->connected == BLKIF_STATE_CONNECTED) ||
840 (info->connected == BLKIF_STATE_SUSPENDED) )
841 return;
842
843 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
844 __func__, info->xbdev->otherend);
845
846 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
847 "sectors", "%llu", &sectors,
848 "info", "%u", &binfo,
849 "sector-size", "%lu", &sector_size,
850 NULL);
851 if (err) {
852 xenbus_dev_fatal(info->xbdev, err,
853 "reading backend fields at %s",
854 info->xbdev->otherend);
855 return;
856 }
857
858 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
859 "feature-barrier", "%lu", &info->feature_barrier,
860 NULL);
861 if (err)
862 info->feature_barrier = 0;
863
864 err = xlvbd_alloc_gendisk(BLKIF_MINOR(info->vdevice),
865 sectors, info->vdevice,
866 binfo, sector_size, info);
867 if (err) {
868 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
869 info->xbdev->otherend);
870 return;
871 }
872
873 xenbus_switch_state(info->xbdev, XenbusStateConnected);
874
875 /* Kick pending requests. */
876 spin_lock_irq(&blkif_io_lock);
877 info->connected = BLKIF_STATE_CONNECTED;
878 kick_pending_request_queues(info);
879 spin_unlock_irq(&blkif_io_lock);
880
881 add_disk(info->gd);
Christian Limpach1d78d702008-04-02 10:54:04 -0700882
883 info->is_ready = 1;
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700884}
885
886/**
887 * Handle the change of state of the backend to Closing. We must delete our
888 * device-layer structures now, to ensure that writes are flushed through to
889 * the backend. Once is this done, we can switch to Closed in
890 * acknowledgement.
891 */
892static void blkfront_closing(struct xenbus_device *dev)
893{
894 struct blkfront_info *info = dev->dev.driver_data;
895 unsigned long flags;
896
897 dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename);
898
899 if (info->rq == NULL)
900 goto out;
901
902 spin_lock_irqsave(&blkif_io_lock, flags);
903
904 del_gendisk(info->gd);
905
906 /* No more blkif_request(). */
907 blk_stop_queue(info->rq);
908
909 /* No more gnttab callback work. */
910 gnttab_cancel_free_callback(&info->callback);
911 spin_unlock_irqrestore(&blkif_io_lock, flags);
912
913 /* Flush gnttab callback work. Must be done with no locks held. */
914 flush_scheduled_work();
915
916 blk_cleanup_queue(info->rq);
917 info->rq = NULL;
918
919 out:
920 xenbus_frontend_closed(dev);
921}
922
923/**
924 * Callback received when the backend's state changes.
925 */
926static void backend_changed(struct xenbus_device *dev,
927 enum xenbus_state backend_state)
928{
929 struct blkfront_info *info = dev->dev.driver_data;
930 struct block_device *bd;
931
932 dev_dbg(&dev->dev, "blkfront:backend_changed.\n");
933
934 switch (backend_state) {
935 case XenbusStateInitialising:
936 case XenbusStateInitWait:
937 case XenbusStateInitialised:
938 case XenbusStateUnknown:
939 case XenbusStateClosed:
940 break;
941
942 case XenbusStateConnected:
943 blkfront_connect(info);
944 break;
945
946 case XenbusStateClosing:
Jeremy Fitzhardinge53f0e8a2008-04-02 10:54:03 -0700947 bd = bdget_disk(info->gd, 0);
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700948 if (bd == NULL)
949 xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
950
951 mutex_lock(&bd->bd_mutex);
952 if (info->users > 0)
953 xenbus_dev_error(dev, -EBUSY,
954 "Device in use; refusing to close");
955 else
956 blkfront_closing(dev);
957 mutex_unlock(&bd->bd_mutex);
958 bdput(bd);
959 break;
960 }
961}
962
963static int blkfront_remove(struct xenbus_device *dev)
964{
965 struct blkfront_info *info = dev->dev.driver_data;
966
967 dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename);
968
969 blkif_free(info, 0);
970
971 kfree(info);
972
973 return 0;
974}
975
Christian Limpach1d78d702008-04-02 10:54:04 -0700976static int blkfront_is_ready(struct xenbus_device *dev)
977{
978 struct blkfront_info *info = dev->dev.driver_data;
979
980 return info->is_ready;
981}
982
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -0700983static int blkif_open(struct inode *inode, struct file *filep)
984{
985 struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
986 info->users++;
987 return 0;
988}
989
990static int blkif_release(struct inode *inode, struct file *filep)
991{
992 struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
993 info->users--;
994 if (info->users == 0) {
995 /* Check whether we have been instructed to close. We will
996 have ignored this request initially, as the device was
997 still mounted. */
998 struct xenbus_device *dev = info->xbdev;
999 enum xenbus_state state = xenbus_read_driver_state(dev->otherend);
1000
Wim Colgate04c06352008-06-17 10:47:08 +02001001 if (state == XenbusStateClosing && info->is_ready)
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -07001002 blkfront_closing(dev);
1003 }
1004 return 0;
1005}
1006
1007static struct block_device_operations xlvbd_block_fops =
1008{
1009 .owner = THIS_MODULE,
1010 .open = blkif_open,
1011 .release = blkif_release,
Ian Campbell597592d2008-02-21 13:03:45 -08001012 .getgeo = blkif_getgeo,
Christian Limpach440a01a2008-06-17 10:47:08 +02001013 .ioctl = blkif_ioctl,
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -07001014};
1015
1016
1017static struct xenbus_device_id blkfront_ids[] = {
1018 { "vbd" },
1019 { "" }
1020};
1021
1022static struct xenbus_driver blkfront = {
1023 .name = "vbd",
1024 .owner = THIS_MODULE,
1025 .ids = blkfront_ids,
1026 .probe = blkfront_probe,
1027 .remove = blkfront_remove,
1028 .resume = blkfront_resume,
1029 .otherend_changed = backend_changed,
Christian Limpach1d78d702008-04-02 10:54:04 -07001030 .is_ready = blkfront_is_ready,
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -07001031};
1032
1033static int __init xlblk_init(void)
1034{
1035 if (!is_running_on_xen())
1036 return -ENODEV;
1037
1038 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1039 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1040 XENVBD_MAJOR, DEV_NAME);
1041 return -ENODEV;
1042 }
1043
1044 return xenbus_register_frontend(&blkfront);
1045}
1046module_init(xlblk_init);
1047
1048
Jan Beulich5a60d0c2008-06-17 10:47:08 +02001049static void __exit xlblk_exit(void)
Jeremy Fitzhardinge9f27ee52007-07-17 18:37:06 -07001050{
1051 return xenbus_unregister_driver(&blkfront);
1052}
1053module_exit(xlblk_exit);
1054
1055MODULE_DESCRIPTION("Xen virtual block device frontend");
1056MODULE_LICENSE("GPL");
1057MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
Mark McLoughlind2f0c522008-04-02 10:54:05 -07001058MODULE_ALIAS("xen:vbd");
Mark McLoughlin4f93f09b2008-04-02 10:54:06 -07001059MODULE_ALIAS("xenblk");