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