xen: Implement getgeo for Xen virtual block device.
[sfrench/cifs-2.6.git] / drivers / block / xen-blkfront.c
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/module.h>
42
43 #include <xen/xenbus.h>
44 #include <xen/grant_table.h>
45 #include <xen/events.h>
46 #include <xen/page.h>
47
48 #include <xen/interface/grant_table.h>
49 #include <xen/interface/io/blkif.h>
50
51 #include <asm/xen/hypervisor.h>
52
53 enum blkif_state {
54         BLKIF_STATE_DISCONNECTED,
55         BLKIF_STATE_CONNECTED,
56         BLKIF_STATE_SUSPENDED,
57 };
58
59 struct blk_shadow {
60         struct blkif_request req;
61         unsigned long request;
62         unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
63 };
64
65 static struct block_device_operations xlvbd_block_fops;
66
67 #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
68
69 /*
70  * We have one of these per vbd, whether ide, scsi or 'other'.  They
71  * hang in private_data off the gendisk structure. We may end up
72  * putting all kinds of interesting stuff here :-)
73  */
74 struct blkfront_info
75 {
76         struct xenbus_device *xbdev;
77         dev_t dev;
78         struct gendisk *gd;
79         int vdevice;
80         blkif_vdev_t handle;
81         enum blkif_state connected;
82         int ring_ref;
83         struct blkif_front_ring ring;
84         unsigned int evtchn, irq;
85         struct request_queue *rq;
86         struct work_struct work;
87         struct gnttab_free_callback callback;
88         struct blk_shadow shadow[BLK_RING_SIZE];
89         unsigned long shadow_free;
90         int feature_barrier;
91
92         /**
93          * The number of people holding this device open.  We won't allow a
94          * hot-unplug unless this is 0.
95          */
96         int users;
97 };
98
99 static DEFINE_SPINLOCK(blkif_io_lock);
100
101 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
102         (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
103 #define GRANT_INVALID_REF       0
104
105 #define PARTS_PER_DISK          16
106
107 #define BLKIF_MAJOR(dev) ((dev)>>8)
108 #define BLKIF_MINOR(dev) ((dev) & 0xff)
109
110 #define DEV_NAME        "xvd"   /* name in /dev */
111
112 /* Information about our VBDs. */
113 #define MAX_VBDS 64
114 static LIST_HEAD(vbds_list);
115
116 static int get_id_from_freelist(struct blkfront_info *info)
117 {
118         unsigned long free = info->shadow_free;
119         BUG_ON(free > BLK_RING_SIZE);
120         info->shadow_free = info->shadow[free].req.id;
121         info->shadow[free].req.id = 0x0fffffee; /* debug */
122         return free;
123 }
124
125 static void add_id_to_freelist(struct blkfront_info *info,
126                                unsigned long id)
127 {
128         info->shadow[id].req.id  = info->shadow_free;
129         info->shadow[id].request = 0;
130         info->shadow_free = id;
131 }
132
133 static void blkif_restart_queue_callback(void *arg)
134 {
135         struct blkfront_info *info = (struct blkfront_info *)arg;
136         schedule_work(&info->work);
137 }
138
139 int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
140 {
141         /* We don't have real geometry info, but let's at least return
142            values consistent with the size of the device */
143         sector_t nsect = get_capacity(bd->bd_disk);
144         sector_t cylinders = nsect;
145
146         hg->heads = 0xff;
147         hg->sectors = 0x3f;
148         sector_div(cylinders, hg->heads * hg->sectors);
149         hg->cylinders = cylinders;
150         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
151                 hg->cylinders = 0xffff;
152         return 0;
153 }
154
155 /*
156  * blkif_queue_request
157  *
158  * request block io
159  *
160  * id: for guest use only.
161  * operation: BLKIF_OP_{READ,WRITE,PROBE}
162  * buffer: buffer to read/write into. this should be a
163  *   virtual address in the guest os.
164  */
165 static int blkif_queue_request(struct request *req)
166 {
167         struct blkfront_info *info = req->rq_disk->private_data;
168         unsigned long buffer_mfn;
169         struct blkif_request *ring_req;
170         struct req_iterator iter;
171         struct bio_vec *bvec;
172         unsigned long id;
173         unsigned int fsect, lsect;
174         int ref;
175         grant_ref_t gref_head;
176
177         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
178                 return 1;
179
180         if (gnttab_alloc_grant_references(
181                 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
182                 gnttab_request_free_callback(
183                         &info->callback,
184                         blkif_restart_queue_callback,
185                         info,
186                         BLKIF_MAX_SEGMENTS_PER_REQUEST);
187                 return 1;
188         }
189
190         /* Fill out a communications ring structure. */
191         ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
192         id = get_id_from_freelist(info);
193         info->shadow[id].request = (unsigned long)req;
194
195         ring_req->id = id;
196         ring_req->sector_number = (blkif_sector_t)req->sector;
197         ring_req->handle = info->handle;
198
199         ring_req->operation = rq_data_dir(req) ?
200                 BLKIF_OP_WRITE : BLKIF_OP_READ;
201         if (blk_barrier_rq(req))
202                 ring_req->operation = BLKIF_OP_WRITE_BARRIER;
203
204         ring_req->nr_segments = 0;
205         rq_for_each_segment(bvec, req, iter) {
206                 BUG_ON(ring_req->nr_segments == BLKIF_MAX_SEGMENTS_PER_REQUEST);
207                 buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page));
208                 fsect = bvec->bv_offset >> 9;
209                 lsect = fsect + (bvec->bv_len >> 9) - 1;
210                 /* install a grant reference. */
211                 ref = gnttab_claim_grant_reference(&gref_head);
212                 BUG_ON(ref == -ENOSPC);
213
214                 gnttab_grant_foreign_access_ref(
215                                 ref,
216                                 info->xbdev->otherend_id,
217                                 buffer_mfn,
218                                 rq_data_dir(req) );
219
220                 info->shadow[id].frame[ring_req->nr_segments] =
221                                 mfn_to_pfn(buffer_mfn);
222
223                 ring_req->seg[ring_req->nr_segments] =
224                                 (struct blkif_request_segment) {
225                                         .gref       = ref,
226                                         .first_sect = fsect,
227                                         .last_sect  = lsect };
228
229                 ring_req->nr_segments++;
230         }
231
232         info->ring.req_prod_pvt++;
233
234         /* Keep a private copy so we can reissue requests when recovering. */
235         info->shadow[id].req = *ring_req;
236
237         gnttab_free_grant_references(gref_head);
238
239         return 0;
240 }
241
242
243 static inline void flush_requests(struct blkfront_info *info)
244 {
245         int notify;
246
247         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
248
249         if (notify)
250                 notify_remote_via_irq(info->irq);
251 }
252
253 /*
254  * do_blkif_request
255  *  read a block; request is in a request queue
256  */
257 static void do_blkif_request(struct request_queue *rq)
258 {
259         struct blkfront_info *info = NULL;
260         struct request *req;
261         int queued;
262
263         pr_debug("Entered do_blkif_request\n");
264
265         queued = 0;
266
267         while ((req = elv_next_request(rq)) != NULL) {
268                 info = req->rq_disk->private_data;
269                 if (!blk_fs_request(req)) {
270                         end_request(req, 0);
271                         continue;
272                 }
273
274                 if (RING_FULL(&info->ring))
275                         goto wait;
276
277                 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
278                          "(%u/%li) buffer:%p [%s]\n",
279                          req, req->cmd, (unsigned long)req->sector,
280                          req->current_nr_sectors,
281                          req->nr_sectors, req->buffer,
282                          rq_data_dir(req) ? "write" : "read");
283
284
285                 blkdev_dequeue_request(req);
286                 if (blkif_queue_request(req)) {
287                         blk_requeue_request(rq, req);
288 wait:
289                         /* Avoid pointless unplugs. */
290                         blk_stop_queue(rq);
291                         break;
292                 }
293
294                 queued++;
295         }
296
297         if (queued != 0)
298                 flush_requests(info);
299 }
300
301 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
302 {
303         struct request_queue *rq;
304
305         rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
306         if (rq == NULL)
307                 return -1;
308
309         elevator_init(rq, "noop");
310
311         /* Hard sector size and max sectors impersonate the equiv. hardware. */
312         blk_queue_hardsect_size(rq, sector_size);
313         blk_queue_max_sectors(rq, 512);
314
315         /* Each segment in a request is up to an aligned page in size. */
316         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
317         blk_queue_max_segment_size(rq, PAGE_SIZE);
318
319         /* Ensure a merged request will fit in a single I/O ring slot. */
320         blk_queue_max_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
321         blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
322
323         /* Make sure buffer addresses are sector-aligned. */
324         blk_queue_dma_alignment(rq, 511);
325
326         gd->queue = rq;
327
328         return 0;
329 }
330
331
332 static int xlvbd_barrier(struct blkfront_info *info)
333 {
334         int err;
335
336         err = blk_queue_ordered(info->rq,
337                                 info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE,
338                                 NULL);
339
340         if (err)
341                 return err;
342
343         printk(KERN_INFO "blkfront: %s: barriers %s\n",
344                info->gd->disk_name,
345                info->feature_barrier ? "enabled" : "disabled");
346         return 0;
347 }
348
349
350 static int xlvbd_alloc_gendisk(int minor, blkif_sector_t capacity,
351                                int vdevice, u16 vdisk_info, u16 sector_size,
352                                struct blkfront_info *info)
353 {
354         struct gendisk *gd;
355         int nr_minors = 1;
356         int err = -ENODEV;
357
358         BUG_ON(info->gd != NULL);
359         BUG_ON(info->rq != NULL);
360
361         if ((minor % PARTS_PER_DISK) == 0)
362                 nr_minors = PARTS_PER_DISK;
363
364         gd = alloc_disk(nr_minors);
365         if (gd == NULL)
366                 goto out;
367
368         if (nr_minors > 1)
369                 sprintf(gd->disk_name, "%s%c", DEV_NAME,
370                         'a' + minor / PARTS_PER_DISK);
371         else
372                 sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
373                         'a' + minor / PARTS_PER_DISK,
374                         minor % PARTS_PER_DISK);
375
376         gd->major = XENVBD_MAJOR;
377         gd->first_minor = minor;
378         gd->fops = &xlvbd_block_fops;
379         gd->private_data = info;
380         gd->driverfs_dev = &(info->xbdev->dev);
381         set_capacity(gd, capacity);
382
383         if (xlvbd_init_blk_queue(gd, sector_size)) {
384                 del_gendisk(gd);
385                 goto out;
386         }
387
388         info->rq = gd->queue;
389         info->gd = gd;
390
391         if (info->feature_barrier)
392                 xlvbd_barrier(info);
393
394         if (vdisk_info & VDISK_READONLY)
395                 set_disk_ro(gd, 1);
396
397         if (vdisk_info & VDISK_REMOVABLE)
398                 gd->flags |= GENHD_FL_REMOVABLE;
399
400         if (vdisk_info & VDISK_CDROM)
401                 gd->flags |= GENHD_FL_CD;
402
403         return 0;
404
405  out:
406         return err;
407 }
408
409 static void kick_pending_request_queues(struct blkfront_info *info)
410 {
411         if (!RING_FULL(&info->ring)) {
412                 /* Re-enable calldowns. */
413                 blk_start_queue(info->rq);
414                 /* Kick things off immediately. */
415                 do_blkif_request(info->rq);
416         }
417 }
418
419 static void blkif_restart_queue(struct work_struct *work)
420 {
421         struct blkfront_info *info = container_of(work, struct blkfront_info, work);
422
423         spin_lock_irq(&blkif_io_lock);
424         if (info->connected == BLKIF_STATE_CONNECTED)
425                 kick_pending_request_queues(info);
426         spin_unlock_irq(&blkif_io_lock);
427 }
428
429 static void blkif_free(struct blkfront_info *info, int suspend)
430 {
431         /* Prevent new requests being issued until we fix things up. */
432         spin_lock_irq(&blkif_io_lock);
433         info->connected = suspend ?
434                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
435         /* No more blkif_request(). */
436         if (info->rq)
437                 blk_stop_queue(info->rq);
438         /* No more gnttab callback work. */
439         gnttab_cancel_free_callback(&info->callback);
440         spin_unlock_irq(&blkif_io_lock);
441
442         /* Flush gnttab callback work. Must be done with no locks held. */
443         flush_scheduled_work();
444
445         /* Free resources associated with old device channel. */
446         if (info->ring_ref != GRANT_INVALID_REF) {
447                 gnttab_end_foreign_access(info->ring_ref, 0,
448                                           (unsigned long)info->ring.sring);
449                 info->ring_ref = GRANT_INVALID_REF;
450                 info->ring.sring = NULL;
451         }
452         if (info->irq)
453                 unbind_from_irqhandler(info->irq, info);
454         info->evtchn = info->irq = 0;
455
456 }
457
458 static void blkif_completion(struct blk_shadow *s)
459 {
460         int i;
461         for (i = 0; i < s->req.nr_segments; i++)
462                 gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
463 }
464
465 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
466 {
467         struct request *req;
468         struct blkif_response *bret;
469         RING_IDX i, rp;
470         unsigned long flags;
471         struct blkfront_info *info = (struct blkfront_info *)dev_id;
472         int error;
473
474         spin_lock_irqsave(&blkif_io_lock, flags);
475
476         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
477                 spin_unlock_irqrestore(&blkif_io_lock, flags);
478                 return IRQ_HANDLED;
479         }
480
481  again:
482         rp = info->ring.sring->rsp_prod;
483         rmb(); /* Ensure we see queued responses up to 'rp'. */
484
485         for (i = info->ring.rsp_cons; i != rp; i++) {
486                 unsigned long id;
487                 int ret;
488
489                 bret = RING_GET_RESPONSE(&info->ring, i);
490                 id   = bret->id;
491                 req  = (struct request *)info->shadow[id].request;
492
493                 blkif_completion(&info->shadow[id]);
494
495                 add_id_to_freelist(info, id);
496
497                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
498                 switch (bret->operation) {
499                 case BLKIF_OP_WRITE_BARRIER:
500                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
501                                 printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
502                                        info->gd->disk_name);
503                                 error = -EOPNOTSUPP;
504                                 info->feature_barrier = 0;
505                                 xlvbd_barrier(info);
506                         }
507                         /* fall through */
508                 case BLKIF_OP_READ:
509                 case BLKIF_OP_WRITE:
510                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
511                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
512                                         "request: %x\n", bret->status);
513
514                         ret = __blk_end_request(req, error, blk_rq_bytes(req));
515                         BUG_ON(ret);
516                         break;
517                 default:
518                         BUG();
519                 }
520         }
521
522         info->ring.rsp_cons = i;
523
524         if (i != info->ring.req_prod_pvt) {
525                 int more_to_do;
526                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
527                 if (more_to_do)
528                         goto again;
529         } else
530                 info->ring.sring->rsp_event = i + 1;
531
532         kick_pending_request_queues(info);
533
534         spin_unlock_irqrestore(&blkif_io_lock, flags);
535
536         return IRQ_HANDLED;
537 }
538
539
540 static int setup_blkring(struct xenbus_device *dev,
541                          struct blkfront_info *info)
542 {
543         struct blkif_sring *sring;
544         int err;
545
546         info->ring_ref = GRANT_INVALID_REF;
547
548         sring = (struct blkif_sring *)__get_free_page(GFP_KERNEL);
549         if (!sring) {
550                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
551                 return -ENOMEM;
552         }
553         SHARED_RING_INIT(sring);
554         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
555
556         err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
557         if (err < 0) {
558                 free_page((unsigned long)sring);
559                 info->ring.sring = NULL;
560                 goto fail;
561         }
562         info->ring_ref = err;
563
564         err = xenbus_alloc_evtchn(dev, &info->evtchn);
565         if (err)
566                 goto fail;
567
568         err = bind_evtchn_to_irqhandler(info->evtchn,
569                                         blkif_interrupt,
570                                         IRQF_SAMPLE_RANDOM, "blkif", info);
571         if (err <= 0) {
572                 xenbus_dev_fatal(dev, err,
573                                  "bind_evtchn_to_irqhandler failed");
574                 goto fail;
575         }
576         info->irq = err;
577
578         return 0;
579 fail:
580         blkif_free(info, 0);
581         return err;
582 }
583
584
585 /* Common code used when first setting up, and when resuming. */
586 static int talk_to_backend(struct xenbus_device *dev,
587                            struct blkfront_info *info)
588 {
589         const char *message = NULL;
590         struct xenbus_transaction xbt;
591         int err;
592
593         /* Create shared ring, alloc event channel. */
594         err = setup_blkring(dev, info);
595         if (err)
596                 goto out;
597
598 again:
599         err = xenbus_transaction_start(&xbt);
600         if (err) {
601                 xenbus_dev_fatal(dev, err, "starting transaction");
602                 goto destroy_blkring;
603         }
604
605         err = xenbus_printf(xbt, dev->nodename,
606                             "ring-ref", "%u", info->ring_ref);
607         if (err) {
608                 message = "writing ring-ref";
609                 goto abort_transaction;
610         }
611         err = xenbus_printf(xbt, dev->nodename,
612                             "event-channel", "%u", info->evtchn);
613         if (err) {
614                 message = "writing event-channel";
615                 goto abort_transaction;
616         }
617
618         err = xenbus_transaction_end(xbt, 0);
619         if (err) {
620                 if (err == -EAGAIN)
621                         goto again;
622                 xenbus_dev_fatal(dev, err, "completing transaction");
623                 goto destroy_blkring;
624         }
625
626         xenbus_switch_state(dev, XenbusStateInitialised);
627
628         return 0;
629
630  abort_transaction:
631         xenbus_transaction_end(xbt, 1);
632         if (message)
633                 xenbus_dev_fatal(dev, err, "%s", message);
634  destroy_blkring:
635         blkif_free(info, 0);
636  out:
637         return err;
638 }
639
640
641 /**
642  * Entry point to this code when a new device is created.  Allocate the basic
643  * structures and the ring buffer for communication with the backend, and
644  * inform the backend of the appropriate details for those.  Switch to
645  * Initialised state.
646  */
647 static int blkfront_probe(struct xenbus_device *dev,
648                           const struct xenbus_device_id *id)
649 {
650         int err, vdevice, i;
651         struct blkfront_info *info;
652
653         /* FIXME: Use dynamic device id if this is not set. */
654         err = xenbus_scanf(XBT_NIL, dev->nodename,
655                            "virtual-device", "%i", &vdevice);
656         if (err != 1) {
657                 xenbus_dev_fatal(dev, err, "reading virtual-device");
658                 return err;
659         }
660
661         info = kzalloc(sizeof(*info), GFP_KERNEL);
662         if (!info) {
663                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
664                 return -ENOMEM;
665         }
666
667         info->xbdev = dev;
668         info->vdevice = vdevice;
669         info->connected = BLKIF_STATE_DISCONNECTED;
670         INIT_WORK(&info->work, blkif_restart_queue);
671
672         for (i = 0; i < BLK_RING_SIZE; i++)
673                 info->shadow[i].req.id = i+1;
674         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
675
676         /* Front end dir is a number, which is used as the id. */
677         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
678         dev->dev.driver_data = info;
679
680         err = talk_to_backend(dev, info);
681         if (err) {
682                 kfree(info);
683                 dev->dev.driver_data = NULL;
684                 return err;
685         }
686
687         return 0;
688 }
689
690
691 static int blkif_recover(struct blkfront_info *info)
692 {
693         int i;
694         struct blkif_request *req;
695         struct blk_shadow *copy;
696         int j;
697
698         /* Stage 1: Make a safe copy of the shadow state. */
699         copy = kmalloc(sizeof(info->shadow), GFP_KERNEL);
700         if (!copy)
701                 return -ENOMEM;
702         memcpy(copy, info->shadow, sizeof(info->shadow));
703
704         /* Stage 2: Set up free list. */
705         memset(&info->shadow, 0, sizeof(info->shadow));
706         for (i = 0; i < BLK_RING_SIZE; i++)
707                 info->shadow[i].req.id = i+1;
708         info->shadow_free = info->ring.req_prod_pvt;
709         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
710
711         /* Stage 3: Find pending requests and requeue them. */
712         for (i = 0; i < BLK_RING_SIZE; i++) {
713                 /* Not in use? */
714                 if (copy[i].request == 0)
715                         continue;
716
717                 /* Grab a request slot and copy shadow state into it. */
718                 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
719                 *req = copy[i].req;
720
721                 /* We get a new request id, and must reset the shadow state. */
722                 req->id = get_id_from_freelist(info);
723                 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
724
725                 /* Rewrite any grant references invalidated by susp/resume. */
726                 for (j = 0; j < req->nr_segments; j++)
727                         gnttab_grant_foreign_access_ref(
728                                 req->seg[j].gref,
729                                 info->xbdev->otherend_id,
730                                 pfn_to_mfn(info->shadow[req->id].frame[j]),
731                                 rq_data_dir(
732                                         (struct request *)
733                                         info->shadow[req->id].request));
734                 info->shadow[req->id].req = *req;
735
736                 info->ring.req_prod_pvt++;
737         }
738
739         kfree(copy);
740
741         xenbus_switch_state(info->xbdev, XenbusStateConnected);
742
743         spin_lock_irq(&blkif_io_lock);
744
745         /* Now safe for us to use the shared ring */
746         info->connected = BLKIF_STATE_CONNECTED;
747
748         /* Send off requeued requests */
749         flush_requests(info);
750
751         /* Kick any other new requests queued since we resumed */
752         kick_pending_request_queues(info);
753
754         spin_unlock_irq(&blkif_io_lock);
755
756         return 0;
757 }
758
759 /**
760  * We are reconnecting to the backend, due to a suspend/resume, or a backend
761  * driver restart.  We tear down our blkif structure and recreate it, but
762  * leave the device-layer structures intact so that this is transparent to the
763  * rest of the kernel.
764  */
765 static int blkfront_resume(struct xenbus_device *dev)
766 {
767         struct blkfront_info *info = dev->dev.driver_data;
768         int err;
769
770         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
771
772         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
773
774         err = talk_to_backend(dev, info);
775         if (info->connected == BLKIF_STATE_SUSPENDED && !err)
776                 err = blkif_recover(info);
777
778         return err;
779 }
780
781
782 /*
783  * Invoked when the backend is finally 'ready' (and has told produced
784  * the details about the physical device - #sectors, size, etc).
785  */
786 static void blkfront_connect(struct blkfront_info *info)
787 {
788         unsigned long long sectors;
789         unsigned long sector_size;
790         unsigned int binfo;
791         int err;
792
793         if ((info->connected == BLKIF_STATE_CONNECTED) ||
794             (info->connected == BLKIF_STATE_SUSPENDED) )
795                 return;
796
797         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
798                 __func__, info->xbdev->otherend);
799
800         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
801                             "sectors", "%llu", &sectors,
802                             "info", "%u", &binfo,
803                             "sector-size", "%lu", &sector_size,
804                             NULL);
805         if (err) {
806                 xenbus_dev_fatal(info->xbdev, err,
807                                  "reading backend fields at %s",
808                                  info->xbdev->otherend);
809                 return;
810         }
811
812         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
813                             "feature-barrier", "%lu", &info->feature_barrier,
814                             NULL);
815         if (err)
816                 info->feature_barrier = 0;
817
818         err = xlvbd_alloc_gendisk(BLKIF_MINOR(info->vdevice),
819                                   sectors, info->vdevice,
820                                   binfo, sector_size, info);
821         if (err) {
822                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
823                                  info->xbdev->otherend);
824                 return;
825         }
826
827         xenbus_switch_state(info->xbdev, XenbusStateConnected);
828
829         /* Kick pending requests. */
830         spin_lock_irq(&blkif_io_lock);
831         info->connected = BLKIF_STATE_CONNECTED;
832         kick_pending_request_queues(info);
833         spin_unlock_irq(&blkif_io_lock);
834
835         add_disk(info->gd);
836 }
837
838 /**
839  * Handle the change of state of the backend to Closing.  We must delete our
840  * device-layer structures now, to ensure that writes are flushed through to
841  * the backend.  Once is this done, we can switch to Closed in
842  * acknowledgement.
843  */
844 static void blkfront_closing(struct xenbus_device *dev)
845 {
846         struct blkfront_info *info = dev->dev.driver_data;
847         unsigned long flags;
848
849         dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename);
850
851         if (info->rq == NULL)
852                 goto out;
853
854         spin_lock_irqsave(&blkif_io_lock, flags);
855
856         del_gendisk(info->gd);
857
858         /* No more blkif_request(). */
859         blk_stop_queue(info->rq);
860
861         /* No more gnttab callback work. */
862         gnttab_cancel_free_callback(&info->callback);
863         spin_unlock_irqrestore(&blkif_io_lock, flags);
864
865         /* Flush gnttab callback work. Must be done with no locks held. */
866         flush_scheduled_work();
867
868         blk_cleanup_queue(info->rq);
869         info->rq = NULL;
870
871  out:
872         xenbus_frontend_closed(dev);
873 }
874
875 /**
876  * Callback received when the backend's state changes.
877  */
878 static void backend_changed(struct xenbus_device *dev,
879                             enum xenbus_state backend_state)
880 {
881         struct blkfront_info *info = dev->dev.driver_data;
882         struct block_device *bd;
883
884         dev_dbg(&dev->dev, "blkfront:backend_changed.\n");
885
886         switch (backend_state) {
887         case XenbusStateInitialising:
888         case XenbusStateInitWait:
889         case XenbusStateInitialised:
890         case XenbusStateUnknown:
891         case XenbusStateClosed:
892                 break;
893
894         case XenbusStateConnected:
895                 blkfront_connect(info);
896                 break;
897
898         case XenbusStateClosing:
899                 bd = bdget(info->dev);
900                 if (bd == NULL)
901                         xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
902
903                 mutex_lock(&bd->bd_mutex);
904                 if (info->users > 0)
905                         xenbus_dev_error(dev, -EBUSY,
906                                          "Device in use; refusing to close");
907                 else
908                         blkfront_closing(dev);
909                 mutex_unlock(&bd->bd_mutex);
910                 bdput(bd);
911                 break;
912         }
913 }
914
915 static int blkfront_remove(struct xenbus_device *dev)
916 {
917         struct blkfront_info *info = dev->dev.driver_data;
918
919         dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename);
920
921         blkif_free(info, 0);
922
923         kfree(info);
924
925         return 0;
926 }
927
928 static int blkif_open(struct inode *inode, struct file *filep)
929 {
930         struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
931         info->users++;
932         return 0;
933 }
934
935 static int blkif_release(struct inode *inode, struct file *filep)
936 {
937         struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
938         info->users--;
939         if (info->users == 0) {
940                 /* Check whether we have been instructed to close.  We will
941                    have ignored this request initially, as the device was
942                    still mounted. */
943                 struct xenbus_device *dev = info->xbdev;
944                 enum xenbus_state state = xenbus_read_driver_state(dev->otherend);
945
946                 if (state == XenbusStateClosing)
947                         blkfront_closing(dev);
948         }
949         return 0;
950 }
951
952 static struct block_device_operations xlvbd_block_fops =
953 {
954         .owner = THIS_MODULE,
955         .open = blkif_open,
956         .release = blkif_release,
957         .getgeo = blkif_getgeo,
958 };
959
960
961 static struct xenbus_device_id blkfront_ids[] = {
962         { "vbd" },
963         { "" }
964 };
965
966 static struct xenbus_driver blkfront = {
967         .name = "vbd",
968         .owner = THIS_MODULE,
969         .ids = blkfront_ids,
970         .probe = blkfront_probe,
971         .remove = blkfront_remove,
972         .resume = blkfront_resume,
973         .otherend_changed = backend_changed,
974 };
975
976 static int __init xlblk_init(void)
977 {
978         if (!is_running_on_xen())
979                 return -ENODEV;
980
981         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
982                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
983                        XENVBD_MAJOR, DEV_NAME);
984                 return -ENODEV;
985         }
986
987         return xenbus_register_frontend(&blkfront);
988 }
989 module_init(xlblk_init);
990
991
992 static void xlblk_exit(void)
993 {
994         return xenbus_unregister_driver(&blkfront);
995 }
996 module_exit(xlblk_exit);
997
998 MODULE_DESCRIPTION("Xen virtual block device frontend");
999 MODULE_LICENSE("GPL");
1000 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);