?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
clock-mx51: factorize clk_set_parent and clk_get_rate
[wandboard.git] / drivers / block / xen-blkfront.c
blobab735a605cf3f23e0f516b21ae07f0d6c5e7e914
1 /*
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>
40 #include <linux/hdreg.h>
41 #include <linux/cdrom.h>
42 #include <linux/module.h>
43 #include <linux/slab.h>
44 #include <linux/smp_lock.h>
45 #include <linux/scatterlist.h>
46
47 #include <xen/xen.h>
48 #include <xen/xenbus.h>
49 #include <xen/grant_table.h>
50 #include <xen/events.h>
51 #include <xen/page.h>
52 #include <xen/platform_pci.h>
53
54 #include <xen/interface/grant_table.h>
55 #include <xen/interface/io/blkif.h>
56 #include <xen/interface/io/protocols.h>
57
58 #include <asm/xen/hypervisor.h>
59
60 enum blkif_state {
61 BLKIF_STATE_DISCONNECTED,
62 BLKIF_STATE_CONNECTED,
63 BLKIF_STATE_SUSPENDED,
64 };
65
66 struct blk_shadow {
67 struct blkif_request req;
68 unsigned long request;
69 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
70 };
71
72 static const struct block_device_operations xlvbd_block_fops;
73
74 #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
75
76 /*
77 * We have one of these per vbd, whether ide, scsi or 'other'. They
78 * hang in private_data off the gendisk structure. We may end up
79 * putting all kinds of interesting stuff here :-)
80 */
81 struct blkfront_info
82 {
83 struct mutex mutex;
84 struct xenbus_device *xbdev;
85 struct gendisk *gd;
86 int vdevice;
87 blkif_vdev_t handle;
88 enum blkif_state connected;
89 int ring_ref;
90 struct blkif_front_ring ring;
91 struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
92 unsigned int evtchn, irq;
93 struct request_queue *rq;
94 struct work_struct work;
95 struct gnttab_free_callback callback;
96 struct blk_shadow shadow[BLK_RING_SIZE];
97 unsigned long shadow_free;
98 int feature_barrier;
99 int is_ready;
100 };
101
102 static DEFINE_SPINLOCK(blkif_io_lock);
103
104 static unsigned int nr_minors;
105 static unsigned long *minors;
106 static DEFINE_SPINLOCK(minor_lock);
107
108 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
109 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
110 #define GRANT_INVALID_REF 0
111
112 #define PARTS_PER_DISK 16
113 #define PARTS_PER_EXT_DISK 256
114
115 #define BLKIF_MAJOR(dev) ((dev)>>8)
116 #define BLKIF_MINOR(dev) ((dev) & 0xff)
117
118 #define EXT_SHIFT 28
119 #define EXTENDED (1<<EXT_SHIFT)
120 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
121 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
122
123 #define DEV_NAME "xvd" /* name in /dev */
124
125 static int get_id_from_freelist(struct blkfront_info *info)
126 {
127 unsigned long free = info->shadow_free;
128 BUG_ON(free >= BLK_RING_SIZE);
129 info->shadow_free = info->shadow[free].req.id;
130 info->shadow[free].req.id = 0x0fffffee; /* debug */
131 return free;
132 }
133
134 static void add_id_to_freelist(struct blkfront_info *info,
135 unsigned long id)
136 {
137 info->shadow[id].req.id = info->shadow_free;
138 info->shadow[id].request = 0;
139 info->shadow_free = id;
140 }
141
142 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
143 {
144 unsigned int end = minor + nr;
145 int rc;
146
147 if (end > nr_minors) {
148 unsigned long *bitmap, *old;
149
150 bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
151 GFP_KERNEL);
152 if (bitmap == NULL)
153 return -ENOMEM;
154
155 spin_lock(&minor_lock);
156 if (end > nr_minors) {
157 old = minors;
158 memcpy(bitmap, minors,
159 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
160 minors = bitmap;
161 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
162 } else
163 old = bitmap;
164 spin_unlock(&minor_lock);
165 kfree(old);
166 }
167
168 spin_lock(&minor_lock);
169 if (find_next_bit(minors, end, minor) >= end) {
170 for (; minor < end; ++minor)
171 __set_bit(minor, minors);
172 rc = 0;
173 } else
174 rc = -EBUSY;
175 spin_unlock(&minor_lock);
176
177 return rc;
178 }
179
180 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
181 {
182 unsigned int end = minor + nr;
183
184 BUG_ON(end > nr_minors);
185 spin_lock(&minor_lock);
186 for (; minor < end; ++minor)
187 __clear_bit(minor, minors);
188 spin_unlock(&minor_lock);
189 }
190
191 static void blkif_restart_queue_callback(void *arg)
192 {
193 struct blkfront_info *info = (struct blkfront_info *)arg;
194 schedule_work(&info->work);
195 }
196
197 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
198 {
199 /* We don't have real geometry info, but let's at least return
200 values consistent with the size of the device */
201 sector_t nsect = get_capacity(bd->bd_disk);
202 sector_t cylinders = nsect;
203
204 hg->heads = 0xff;
205 hg->sectors = 0x3f;
206 sector_div(cylinders, hg->heads * hg->sectors);
207 hg->cylinders = cylinders;
208 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
209 hg->cylinders = 0xffff;
210 return 0;
211 }
212
213 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
214 unsigned command, unsigned long argument)
215 {
216 struct blkfront_info *info = bdev->bd_disk->private_data;
217 int i;
218
219 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
220 command, (long)argument);
221
222 switch (command) {
223 case CDROMMULTISESSION:
224 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
225 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
226 if (put_user(0, (char __user *)(argument + i)))
227 return -EFAULT;
228 return 0;
229
230 case CDROM_GET_CAPABILITY: {
231 struct gendisk *gd = info->gd;
232 if (gd->flags & GENHD_FL_CD)
233 return 0;
234 return -EINVAL;
235 }
236
237 default:
238 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
239 command);*/
240 return -EINVAL; /* same return as native Linux */
241 }
242
243 return 0;
244 }
245
246 /*
247 * blkif_queue_request
248 *
249 * request block io
250 *
251 * id: for guest use only.
252 * operation: BLKIF_OP_{READ,WRITE,PROBE}
253 * buffer: buffer to read/write into. this should be a
254 * virtual address in the guest os.
255 */
256 static int blkif_queue_request(struct request *req)
257 {
258 struct blkfront_info *info = req->rq_disk->private_data;
259 unsigned long buffer_mfn;
260 struct blkif_request *ring_req;
261 unsigned long id;
262 unsigned int fsect, lsect;
263 int i, ref;
264 grant_ref_t gref_head;
265 struct scatterlist *sg;
266
267 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
268 return 1;
269
270 if (gnttab_alloc_grant_references(
271 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
272 gnttab_request_free_callback(
273 &info->callback,
274 blkif_restart_queue_callback,
275 info,
276 BLKIF_MAX_SEGMENTS_PER_REQUEST);
277 return 1;
278 }
279
280 /* Fill out a communications ring structure. */
281 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
282 id = get_id_from_freelist(info);
283 info->shadow[id].request = (unsigned long)req;
284
285 ring_req->id = id;
286 ring_req->sector_number = (blkif_sector_t)blk_rq_pos(req);
287 ring_req->handle = info->handle;
288
289 ring_req->operation = rq_data_dir(req) ?
290 BLKIF_OP_WRITE : BLKIF_OP_READ;
291 if (req->cmd_flags & REQ_HARDBARRIER)
292 ring_req->operation = BLKIF_OP_WRITE_BARRIER;
293
294 ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
295 BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
296
297 for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
298 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
299 fsect = sg->offset >> 9;
300 lsect = fsect + (sg->length >> 9) - 1;
301 /* install a grant reference. */
302 ref = gnttab_claim_grant_reference(&gref_head);
303 BUG_ON(ref == -ENOSPC);
304
305 gnttab_grant_foreign_access_ref(
306 ref,
307 info->xbdev->otherend_id,
308 buffer_mfn,
309 rq_data_dir(req) );
310
311 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
312 ring_req->seg[i] =
313 (struct blkif_request_segment) {
314 .gref = ref,
315 .first_sect = fsect,
316 .last_sect = lsect };
317 }
318
319 info->ring.req_prod_pvt++;
320
321 /* Keep a private copy so we can reissue requests when recovering. */
322 info->shadow[id].req = *ring_req;
323
324 gnttab_free_grant_references(gref_head);
325
326 return 0;
327 }
328
329
330 static inline void flush_requests(struct blkfront_info *info)
331 {
332 int notify;
333
334 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
335
336 if (notify)
337 notify_remote_via_irq(info->irq);
338 }
339
340 /*
341 * do_blkif_request
342 * read a block; request is in a request queue
343 */
344 static void do_blkif_request(struct request_queue *rq)
345 {
346 struct blkfront_info *info = NULL;
347 struct request *req;
348 int queued;
349
350 pr_debug("Entered do_blkif_request\n");
351
352 queued = 0;
353
354 while ((req = blk_peek_request(rq)) != NULL) {
355 info = req->rq_disk->private_data;
356
357 if (RING_FULL(&info->ring))
358 goto wait;
359
360 blk_start_request(req);
361
362 if (req->cmd_type != REQ_TYPE_FS) {
363 __blk_end_request_all(req, -EIO);
364 continue;
365 }
366
367 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
368 "(%u/%u) buffer:%p [%s]\n",
369 req, req->cmd, (unsigned long)blk_rq_pos(req),
370 blk_rq_cur_sectors(req), blk_rq_sectors(req),
371 req->buffer, rq_data_dir(req) ? "write" : "read");
372
373 if (blkif_queue_request(req)) {
374 blk_requeue_request(rq, req);
375 wait:
376 /* Avoid pointless unplugs. */
377 blk_stop_queue(rq);
378 break;
379 }
380
381 queued++;
382 }
383
384 if (queued != 0)
385 flush_requests(info);
386 }
387
388 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
389 {
390 struct request_queue *rq;
391
392 rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
393 if (rq == NULL)
394 return -1;
395
396 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
397
398 /* Hard sector size and max sectors impersonate the equiv. hardware. */
399 blk_queue_logical_block_size(rq, sector_size);
400 blk_queue_max_hw_sectors(rq, 512);
401
402 /* Each segment in a request is up to an aligned page in size. */
403 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
404 blk_queue_max_segment_size(rq, PAGE_SIZE);
405
406 /* Ensure a merged request will fit in a single I/O ring slot. */
407 blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
408
409 /* Make sure buffer addresses are sector-aligned. */
410 blk_queue_dma_alignment(rq, 511);
411
412 /* Make sure we don't use bounce buffers. */
413 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
414
415 gd->queue = rq;
416
417 return 0;
418 }
419
420
421 static int xlvbd_barrier(struct blkfront_info *info)
422 {
423 int err;
424 const char *barrier;
425
426 switch (info->feature_barrier) {
427 case QUEUE_ORDERED_DRAIN: barrier = "enabled (drain)"; break;
428 case QUEUE_ORDERED_TAG: barrier = "enabled (tag)"; break;
429 case QUEUE_ORDERED_NONE: barrier = "disabled"; break;
430 default: return -EINVAL;
431 }
432
433 err = blk_queue_ordered(info->rq, info->feature_barrier);
434
435 if (err)
436 return err;
437
438 printk(KERN_INFO "blkfront: %s: barriers %s\n",
439 info->gd->disk_name, barrier);
440 return 0;
441 }
442
443
444 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
445 struct blkfront_info *info,
446 u16 vdisk_info, u16 sector_size)
447 {
448 struct gendisk *gd;
449 int nr_minors = 1;
450 int err = -ENODEV;
451 unsigned int offset;
452 int minor;
453 int nr_parts;
454
455 BUG_ON(info->gd != NULL);
456 BUG_ON(info->rq != NULL);
457
458 if ((info->vdevice>>EXT_SHIFT) > 1) {
459 /* this is above the extended range; something is wrong */
460 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
461 return -ENODEV;
462 }
463
464 if (!VDEV_IS_EXTENDED(info->vdevice)) {
465 minor = BLKIF_MINOR(info->vdevice);
466 nr_parts = PARTS_PER_DISK;
467 } else {
468 minor = BLKIF_MINOR_EXT(info->vdevice);
469 nr_parts = PARTS_PER_EXT_DISK;
470 }
471
472 if ((minor % nr_parts) == 0)
473 nr_minors = nr_parts;
474
475 err = xlbd_reserve_minors(minor, nr_minors);
476 if (err)
477 goto out;
478 err = -ENODEV;
479
480 gd = alloc_disk(nr_minors);
481 if (gd == NULL)
482 goto release;
483
484 offset = minor / nr_parts;
485
486 if (nr_minors > 1) {
487 if (offset < 26)
488 sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
489 else
490 sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
491 'a' + ((offset / 26)-1), 'a' + (offset % 26));
492 } else {
493 if (offset < 26)
494 sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
495 'a' + offset,
496 minor & (nr_parts - 1));
497 else
498 sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
499 'a' + ((offset / 26) - 1),
500 'a' + (offset % 26),
501 minor & (nr_parts - 1));
502 }
503
504 gd->major = XENVBD_MAJOR;
505 gd->first_minor = minor;
506 gd->fops = &xlvbd_block_fops;
507 gd->private_data = info;
508 gd->driverfs_dev = &(info->xbdev->dev);
509 set_capacity(gd, capacity);
510
511 if (xlvbd_init_blk_queue(gd, sector_size)) {
512 del_gendisk(gd);
513 goto release;
514 }
515
516 info->rq = gd->queue;
517 info->gd = gd;
518
519 xlvbd_barrier(info);
520
521 if (vdisk_info & VDISK_READONLY)
522 set_disk_ro(gd, 1);
523
524 if (vdisk_info & VDISK_REMOVABLE)
525 gd->flags |= GENHD_FL_REMOVABLE;
526
527 if (vdisk_info & VDISK_CDROM)
528 gd->flags |= GENHD_FL_CD;
529
530 return 0;
531
532 release:
533 xlbd_release_minors(minor, nr_minors);
534 out:
535 return err;
536 }
537
538 static void xlvbd_release_gendisk(struct blkfront_info *info)
539 {
540 unsigned int minor, nr_minors;
541 unsigned long flags;
542
543 if (info->rq == NULL)
544 return;
545
546 spin_lock_irqsave(&blkif_io_lock, flags);
547
548 /* No more blkif_request(). */
549 blk_stop_queue(info->rq);
550
551 /* No more gnttab callback work. */
552 gnttab_cancel_free_callback(&info->callback);
553 spin_unlock_irqrestore(&blkif_io_lock, flags);
554
555 /* Flush gnttab callback work. Must be done with no locks held. */
556 flush_scheduled_work();
557
558 del_gendisk(info->gd);
559
560 minor = info->gd->first_minor;
561 nr_minors = info->gd->minors;
562 xlbd_release_minors(minor, nr_minors);
563
564 blk_cleanup_queue(info->rq);
565 info->rq = NULL;
566
567 put_disk(info->gd);
568 info->gd = NULL;
569 }
570
571 static void kick_pending_request_queues(struct blkfront_info *info)
572 {
573 if (!RING_FULL(&info->ring)) {
574 /* Re-enable calldowns. */
575 blk_start_queue(info->rq);
576 /* Kick things off immediately. */
577 do_blkif_request(info->rq);
578 }
579 }
580
581 static void blkif_restart_queue(struct work_struct *work)
582 {
583 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
584
585 spin_lock_irq(&blkif_io_lock);
586 if (info->connected == BLKIF_STATE_CONNECTED)
587 kick_pending_request_queues(info);
588 spin_unlock_irq(&blkif_io_lock);
589 }
590
591 static void blkif_free(struct blkfront_info *info, int suspend)
592 {
593 /* Prevent new requests being issued until we fix things up. */
594 spin_lock_irq(&blkif_io_lock);
595 info->connected = suspend ?
596 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
597 /* No more blkif_request(). */
598 if (info->rq)
599 blk_stop_queue(info->rq);
600 /* No more gnttab callback work. */
601 gnttab_cancel_free_callback(&info->callback);
602 spin_unlock_irq(&blkif_io_lock);
603
604 /* Flush gnttab callback work. Must be done with no locks held. */
605 flush_scheduled_work();
606
607 /* Free resources associated with old device channel. */
608 if (info->ring_ref != GRANT_INVALID_REF) {
609 gnttab_end_foreign_access(info->ring_ref, 0,
610 (unsigned long)info->ring.sring);
611 info->ring_ref = GRANT_INVALID_REF;
612 info->ring.sring = NULL;
613 }
614 if (info->irq)
615 unbind_from_irqhandler(info->irq, info);
616 info->evtchn = info->irq = 0;
617
618 }
619
620 static void blkif_completion(struct blk_shadow *s)
621 {
622 int i;
623 for (i = 0; i < s->req.nr_segments; i++)
624 gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
625 }
626
627 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
628 {
629 struct request *req;
630 struct blkif_response *bret;
631 RING_IDX i, rp;
632 unsigned long flags;
633 struct blkfront_info *info = (struct blkfront_info *)dev_id;
634 int error;
635
636 spin_lock_irqsave(&blkif_io_lock, flags);
637
638 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
639 spin_unlock_irqrestore(&blkif_io_lock, flags);
640 return IRQ_HANDLED;
641 }
642
643 again:
644 rp = info->ring.sring->rsp_prod;
645 rmb(); /* Ensure we see queued responses up to 'rp'. */
646
647 for (i = info->ring.rsp_cons; i != rp; i++) {
648 unsigned long id;
649
650 bret = RING_GET_RESPONSE(&info->ring, i);
651 id = bret->id;
652 req = (struct request *)info->shadow[id].request;
653
654 blkif_completion(&info->shadow[id]);
655
656 add_id_to_freelist(info, id);
657
658 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
659 switch (bret->operation) {
660 case BLKIF_OP_WRITE_BARRIER:
661 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
662 printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
663 info->gd->disk_name);
664 error = -EOPNOTSUPP;
665 info->feature_barrier = QUEUE_ORDERED_NONE;
666 xlvbd_barrier(info);
667 }
668 /* fall through */
669 case BLKIF_OP_READ:
670 case BLKIF_OP_WRITE:
671 if (unlikely(bret->status != BLKIF_RSP_OKAY))
672 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
673 "request: %x\n", bret->status);
674
675 __blk_end_request_all(req, error);
676 break;
677 default:
678 BUG();
679 }
680 }
681
682 info->ring.rsp_cons = i;
683
684 if (i != info->ring.req_prod_pvt) {
685 int more_to_do;
686 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
687 if (more_to_do)
688 goto again;
689 } else
690 info->ring.sring->rsp_event = i + 1;
691
692 kick_pending_request_queues(info);
693
694 spin_unlock_irqrestore(&blkif_io_lock, flags);
695
696 return IRQ_HANDLED;
697 }
698
699
700 static int setup_blkring(struct xenbus_device *dev,
701 struct blkfront_info *info)
702 {
703 struct blkif_sring *sring;
704 int err;
705
706 info->ring_ref = GRANT_INVALID_REF;
707
708 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
709 if (!sring) {
710 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
711 return -ENOMEM;
712 }
713 SHARED_RING_INIT(sring);
714 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
715
716 sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
717
718 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
719 if (err < 0) {
720 free_page((unsigned long)sring);
721 info->ring.sring = NULL;
722 goto fail;
723 }
724 info->ring_ref = err;
725
726 err = xenbus_alloc_evtchn(dev, &info->evtchn);
727 if (err)
728 goto fail;
729
730 err = bind_evtchn_to_irqhandler(info->evtchn,
731 blkif_interrupt,
732 IRQF_SAMPLE_RANDOM, "blkif", info);
733 if (err <= 0) {
734 xenbus_dev_fatal(dev, err,
735 "bind_evtchn_to_irqhandler failed");
736 goto fail;
737 }
738 info->irq = err;
739
740 return 0;
741 fail:
742 blkif_free(info, 0);
743 return err;
744 }
745
746
747 /* Common code used when first setting up, and when resuming. */
748 static int talk_to_blkback(struct xenbus_device *dev,
749 struct blkfront_info *info)
750 {
751 const char *message = NULL;
752 struct xenbus_transaction xbt;
753 int err;
754
755 /* Create shared ring, alloc event channel. */
756 err = setup_blkring(dev, info);
757 if (err)
758 goto out;
759
760 again:
761 err = xenbus_transaction_start(&xbt);
762 if (err) {
763 xenbus_dev_fatal(dev, err, "starting transaction");
764 goto destroy_blkring;
765 }
766
767 err = xenbus_printf(xbt, dev->nodename,
768 "ring-ref", "%u", info->ring_ref);
769 if (err) {
770 message = "writing ring-ref";
771 goto abort_transaction;
772 }
773 err = xenbus_printf(xbt, dev->nodename,
774 "event-channel", "%u", info->evtchn);
775 if (err) {
776 message = "writing event-channel";
777 goto abort_transaction;
778 }
779 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
780 XEN_IO_PROTO_ABI_NATIVE);
781 if (err) {
782 message = "writing protocol";
783 goto abort_transaction;
784 }
785
786 err = xenbus_transaction_end(xbt, 0);
787 if (err) {
788 if (err == -EAGAIN)
789 goto again;
790 xenbus_dev_fatal(dev, err, "completing transaction");
791 goto destroy_blkring;
792 }
793
794 xenbus_switch_state(dev, XenbusStateInitialised);
795
796 return 0;
797
798 abort_transaction:
799 xenbus_transaction_end(xbt, 1);
800 if (message)
801 xenbus_dev_fatal(dev, err, "%s", message);
802 destroy_blkring:
803 blkif_free(info, 0);
804 out:
805 return err;
806 }
807
808 /**
809 * Entry point to this code when a new device is created. Allocate the basic
810 * structures and the ring buffer for communication with the backend, and
811 * inform the backend of the appropriate details for those. Switch to
812 * Initialised state.
813 */
814 static int blkfront_probe(struct xenbus_device *dev,
815 const struct xenbus_device_id *id)
816 {
817 int err, vdevice, i;
818 struct blkfront_info *info;
819
820 /* FIXME: Use dynamic device id if this is not set. */
821 err = xenbus_scanf(XBT_NIL, dev->nodename,
822 "virtual-device", "%i", &vdevice);
823 if (err != 1) {
824 /* go looking in the extended area instead */
825 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
826 "%i", &vdevice);
827 if (err != 1) {
828 xenbus_dev_fatal(dev, err, "reading virtual-device");
829 return err;
830 }
831 }
832
833 if (xen_hvm_domain()) {
834 char *type;
835 int len;
836 /* no unplug has been done: do not hook devices != xen vbds */
837 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
838 int major;
839
840 if (!VDEV_IS_EXTENDED(vdevice))
841 major = BLKIF_MAJOR(vdevice);
842 else
843 major = XENVBD_MAJOR;
844
845 if (major != XENVBD_MAJOR) {
846 printk(KERN_INFO
847 "%s: HVM does not support vbd %d as xen block device\n",
848 __FUNCTION__, vdevice);
849 return -ENODEV;
850 }
851 }
852 /* do not create a PV cdrom device if we are an HVM guest */
853 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
854 if (IS_ERR(type))
855 return -ENODEV;
856 if (strncmp(type, "cdrom", 5) == 0) {
857 kfree(type);
858 return -ENODEV;
859 }
860 kfree(type);
861 }
862 info = kzalloc(sizeof(*info), GFP_KERNEL);
863 if (!info) {
864 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
865 return -ENOMEM;
866 }
867
868 mutex_init(&info->mutex);
869 info->xbdev = dev;
870 info->vdevice = vdevice;
871 info->connected = BLKIF_STATE_DISCONNECTED;
872 INIT_WORK(&info->work, blkif_restart_queue);
873
874 for (i = 0; i < BLK_RING_SIZE; i++)
875 info->shadow[i].req.id = i+1;
876 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
877
878 /* Front end dir is a number, which is used as the id. */
879 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
880 dev_set_drvdata(&dev->dev, info);
881
882 err = talk_to_blkback(dev, info);
883 if (err) {
884 kfree(info);
885 dev_set_drvdata(&dev->dev, NULL);
886 return err;
887 }
888
889 return 0;
890 }
891
892
893 static int blkif_recover(struct blkfront_info *info)
894 {
895 int i;
896 struct blkif_request *req;
897 struct blk_shadow *copy;
898 int j;
899
900 /* Stage 1: Make a safe copy of the shadow state. */
901 copy = kmalloc(sizeof(info->shadow),
902 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
903 if (!copy)
904 return -ENOMEM;
905 memcpy(copy, info->shadow, sizeof(info->shadow));
906
907 /* Stage 2: Set up free list. */
908 memset(&info->shadow, 0, sizeof(info->shadow));
909 for (i = 0; i < BLK_RING_SIZE; i++)
910 info->shadow[i].req.id = i+1;
911 info->shadow_free = info->ring.req_prod_pvt;
912 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
913
914 /* Stage 3: Find pending requests and requeue them. */
915 for (i = 0; i < BLK_RING_SIZE; i++) {
916 /* Not in use? */
917 if (copy[i].request == 0)
918 continue;
919
920 /* Grab a request slot and copy shadow state into it. */
921 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
922 *req = copy[i].req;
923
924 /* We get a new request id, and must reset the shadow state. */
925 req->id = get_id_from_freelist(info);
926 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
927
928 /* Rewrite any grant references invalidated by susp/resume. */
929 for (j = 0; j < req->nr_segments; j++)
930 gnttab_grant_foreign_access_ref(
931 req->seg[j].gref,
932 info->xbdev->otherend_id,
933 pfn_to_mfn(info->shadow[req->id].frame[j]),
934 rq_data_dir(
935 (struct request *)
936 info->shadow[req->id].request));
937 info->shadow[req->id].req = *req;
938
939 info->ring.req_prod_pvt++;
940 }
941
942 kfree(copy);
943
944 xenbus_switch_state(info->xbdev, XenbusStateConnected);
945
946 spin_lock_irq(&blkif_io_lock);
947
948 /* Now safe for us to use the shared ring */
949 info->connected = BLKIF_STATE_CONNECTED;
950
951 /* Send off requeued requests */
952 flush_requests(info);
953
954 /* Kick any other new requests queued since we resumed */
955 kick_pending_request_queues(info);
956
957 spin_unlock_irq(&blkif_io_lock);
958
959 return 0;
960 }
961
962 /**
963 * We are reconnecting to the backend, due to a suspend/resume, or a backend
964 * driver restart. We tear down our blkif structure and recreate it, but
965 * leave the device-layer structures intact so that this is transparent to the
966 * rest of the kernel.
967 */
968 static int blkfront_resume(struct xenbus_device *dev)
969 {
970 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
971 int err;
972
973 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
974
975 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
976
977 err = talk_to_blkback(dev, info);
978 if (info->connected == BLKIF_STATE_SUSPENDED && !err)
979 err = blkif_recover(info);
980
981 return err;
982 }
983
984 static void
985 blkfront_closing(struct blkfront_info *info)
986 {
987 struct xenbus_device *xbdev = info->xbdev;
988 struct block_device *bdev = NULL;
989
990 mutex_lock(&info->mutex);
991
992 if (xbdev->state == XenbusStateClosing) {
993 mutex_unlock(&info->mutex);
994 return;
995 }
996
997 if (info->gd)
998 bdev = bdget_disk(info->gd, 0);
999
1000 mutex_unlock(&info->mutex);
1001
1002 if (!bdev) {
1003 xenbus_frontend_closed(xbdev);
1004 return;
1005 }
1006
1007 mutex_lock(&bdev->bd_mutex);
1008
1009 if (bdev->bd_openers) {
1010 xenbus_dev_error(xbdev, -EBUSY,
1011 "Device in use; refusing to close");
1012 xenbus_switch_state(xbdev, XenbusStateClosing);
1013 } else {
1014 xlvbd_release_gendisk(info);
1015 xenbus_frontend_closed(xbdev);
1016 }
1017
1018 mutex_unlock(&bdev->bd_mutex);
1019 bdput(bdev);
1020 }
1021
1022 /*
1023 * Invoked when the backend is finally 'ready' (and has told produced
1024 * the details about the physical device - #sectors, size, etc).
1025 */
1026 static void blkfront_connect(struct blkfront_info *info)
1027 {
1028 unsigned long long sectors;
1029 unsigned long sector_size;
1030 unsigned int binfo;
1031 int err;
1032 int barrier;
1033
1034 switch (info->connected) {
1035 case BLKIF_STATE_CONNECTED:
1036 /*
1037 * Potentially, the back-end may be signalling
1038 * a capacity change; update the capacity.
1039 */
1040 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1041 "sectors", "%Lu", &sectors);
1042 if (XENBUS_EXIST_ERR(err))
1043 return;
1044 printk(KERN_INFO "Setting capacity to %Lu\n",
1045 sectors);
1046 set_capacity(info->gd, sectors);
1047 revalidate_disk(info->gd);
1048
1049 /* fall through */
1050 case BLKIF_STATE_SUSPENDED:
1051 return;
1052
1053 default:
1054 break;
1055 }
1056
1057 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1058 __func__, info->xbdev->otherend);
1059
1060 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1061 "sectors", "%llu", &sectors,
1062 "info", "%u", &binfo,
1063 "sector-size", "%lu", &sector_size,
1064 NULL);
1065 if (err) {
1066 xenbus_dev_fatal(info->xbdev, err,
1067 "reading backend fields at %s",
1068 info->xbdev->otherend);
1069 return;
1070 }
1071
1072 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1073 "feature-barrier", "%lu", &barrier,
1074 NULL);
1075
1076 /*
1077 * If there's no "feature-barrier" defined, then it means
1078 * we're dealing with a very old backend which writes
1079 * synchronously; draining will do what needs to get done.
1080 *
1081 * If there are barriers, then we can do full queued writes
1082 * with tagged barriers.
1083 *
1084 * If barriers are not supported, then there's no much we can
1085 * do, so just set ordering to NONE.
1086 */
1087 if (err)
1088 info->feature_barrier = QUEUE_ORDERED_DRAIN;
1089 else if (barrier)
1090 info->feature_barrier = QUEUE_ORDERED_TAG;
1091 else
1092 info->feature_barrier = QUEUE_ORDERED_NONE;
1093
1094 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1095 if (err) {
1096 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1097 info->xbdev->otherend);
1098 return;
1099 }
1100
1101 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1102
1103 /* Kick pending requests. */
1104 spin_lock_irq(&blkif_io_lock);
1105 info->connected = BLKIF_STATE_CONNECTED;
1106 kick_pending_request_queues(info);
1107 spin_unlock_irq(&blkif_io_lock);
1108
1109 add_disk(info->gd);
1110
1111 info->is_ready = 1;
1112 }
1113
1114 /**
1115 * Callback received when the backend's state changes.
1116 */
1117 static void blkback_changed(struct xenbus_device *dev,
1118 enum xenbus_state backend_state)
1119 {
1120 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1121
1122 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1123
1124 switch (backend_state) {
1125 case XenbusStateInitialising:
1126 case XenbusStateInitWait:
1127 case XenbusStateInitialised:
1128 case XenbusStateUnknown:
1129 case XenbusStateClosed:
1130 break;
1131
1132 case XenbusStateConnected:
1133 blkfront_connect(info);
1134 break;
1135
1136 case XenbusStateClosing:
1137 blkfront_closing(info);
1138 break;
1139 }
1140 }
1141
1142 static int blkfront_remove(struct xenbus_device *xbdev)
1143 {
1144 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1145 struct block_device *bdev = NULL;
1146 struct gendisk *disk;
1147
1148 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1149
1150 blkif_free(info, 0);
1151
1152 mutex_lock(&info->mutex);
1153
1154 disk = info->gd;
1155 if (disk)
1156 bdev = bdget_disk(disk, 0);
1157
1158 info->xbdev = NULL;
1159 mutex_unlock(&info->mutex);
1160
1161 if (!bdev) {
1162 kfree(info);
1163 return 0;
1164 }
1165
1166 /*
1167 * The xbdev was removed before we reached the Closed
1168 * state. See if it's safe to remove the disk. If the bdev
1169 * isn't closed yet, we let release take care of it.
1170 */
1171
1172 mutex_lock(&bdev->bd_mutex);
1173 info = disk->private_data;
1174
1175 dev_warn(disk_to_dev(disk),
1176 "%s was hot-unplugged, %d stale handles\n",
1177 xbdev->nodename, bdev->bd_openers);
1178
1179 if (info && !bdev->bd_openers) {
1180 xlvbd_release_gendisk(info);
1181 disk->private_data = NULL;
1182 kfree(info);
1183 }
1184
1185 mutex_unlock(&bdev->bd_mutex);
1186 bdput(bdev);
1187
1188 return 0;
1189 }
1190
1191 static int blkfront_is_ready(struct xenbus_device *dev)
1192 {
1193 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1194
1195 return info->is_ready && info->xbdev;
1196 }
1197
1198 static int blkif_open(struct block_device *bdev, fmode_t mode)
1199 {
1200 struct gendisk *disk = bdev->bd_disk;
1201 struct blkfront_info *info;
1202 int err = 0;
1203
1204 lock_kernel();
1205
1206 info = disk->private_data;
1207 if (!info) {
1208 /* xbdev gone */
1209 err = -ERESTARTSYS;
1210 goto out;
1211 }
1212
1213 mutex_lock(&info->mutex);
1214
1215 if (!info->gd)
1216 /* xbdev is closed */
1217 err = -ERESTARTSYS;
1218
1219 mutex_unlock(&info->mutex);
1220
1221 out:
1222 unlock_kernel();
1223 return err;
1224 }
1225
1226 static int blkif_release(struct gendisk *disk, fmode_t mode)
1227 {
1228 struct blkfront_info *info = disk->private_data;
1229 struct block_device *bdev;
1230 struct xenbus_device *xbdev;
1231
1232 lock_kernel();
1233
1234 bdev = bdget_disk(disk, 0);
1235 bdput(bdev);
1236
1237 if (bdev->bd_openers)
1238 goto out;
1239
1240 /*
1241 * Check if we have been instructed to close. We will have
1242 * deferred this request, because the bdev was still open.
1243 */
1244
1245 mutex_lock(&info->mutex);
1246 xbdev = info->xbdev;
1247
1248 if (xbdev && xbdev->state == XenbusStateClosing) {
1249 /* pending switch to state closed */
1250 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1251 xlvbd_release_gendisk(info);
1252 xenbus_frontend_closed(info->xbdev);
1253 }
1254
1255 mutex_unlock(&info->mutex);
1256
1257 if (!xbdev) {
1258 /* sudden device removal */
1259 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1260 xlvbd_release_gendisk(info);
1261 disk->private_data = NULL;
1262 kfree(info);
1263 }
1264
1265 out:
1266 unlock_kernel();
1267 return 0;
1268 }
1269
1270 static const struct block_device_operations xlvbd_block_fops =
1271 {
1272 .owner = THIS_MODULE,
1273 .open = blkif_open,
1274 .release = blkif_release,
1275 .getgeo = blkif_getgeo,
1276 .ioctl = blkif_ioctl,
1277 };
1278
1279
1280 static const struct xenbus_device_id blkfront_ids[] = {
1281 { "vbd" },
1282 { "" }
1283 };
1284
1285 static struct xenbus_driver blkfront = {
1286 .name = "vbd",
1287 .owner = THIS_MODULE,
1288 .ids = blkfront_ids,
1289 .probe = blkfront_probe,
1290 .remove = blkfront_remove,
1291 .resume = blkfront_resume,
1292 .otherend_changed = blkback_changed,
1293 .is_ready = blkfront_is_ready,
1294 };
1295
1296 static int __init xlblk_init(void)
1297 {
1298 if (!xen_domain())
1299 return -ENODEV;
1300
1301 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1302 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1303 XENVBD_MAJOR, DEV_NAME);
1304 return -ENODEV;
1305 }
1306
1307 return xenbus_register_frontend(&blkfront);
1308 }
1309 module_init(xlblk_init);
1310
1311
1312 static void __exit xlblk_exit(void)
1313 {
1314 return xenbus_unregister_driver(&blkfront);
1315 }
1316 module_exit(xlblk_exit);
1317
1318 MODULE_DESCRIPTION("Xen virtual block device frontend");
1319 MODULE_LICENSE("GPL");
1320 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1321 MODULE_ALIAS("xen:vbd");
1322 MODULE_ALIAS("xenblk");
WandBoard kernel