4276ab035e006a80cd0283a5f591a03f4de4b289
[~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         struct request *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 __CONST_RING_SIZE(blkif, 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         unsigned int flush_op;
101         unsigned int feature_discard;
102         unsigned int discard_granularity;
103         unsigned int discard_alignment;
104         int is_ready;
105 };
106
107 static DEFINE_SPINLOCK(blkif_io_lock);
108
109 static unsigned int nr_minors;
110 static unsigned long *minors;
111 static DEFINE_SPINLOCK(minor_lock);
112
113 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
114         (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
115 #define GRANT_INVALID_REF       0
116
117 #define PARTS_PER_DISK          16
118 #define PARTS_PER_EXT_DISK      256
119
120 #define BLKIF_MAJOR(dev) ((dev)>>8)
121 #define BLKIF_MINOR(dev) ((dev) & 0xff)
122
123 #define EXT_SHIFT 28
124 #define EXTENDED (1<<EXT_SHIFT)
125 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
126 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
127 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
128 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
129 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
130 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
131
132 #define DEV_NAME        "xvd"   /* name in /dev */
133
134 static int get_id_from_freelist(struct blkfront_info *info)
135 {
136         unsigned long free = info->shadow_free;
137         BUG_ON(free >= BLK_RING_SIZE);
138         info->shadow_free = info->shadow[free].req.id;
139         info->shadow[free].req.id = 0x0fffffee; /* debug */
140         return free;
141 }
142
143 static void add_id_to_freelist(struct blkfront_info *info,
144                                unsigned long id)
145 {
146         info->shadow[id].req.id  = info->shadow_free;
147         info->shadow[id].request = NULL;
148         info->shadow_free = id;
149 }
150
151 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
152 {
153         unsigned int end = minor + nr;
154         int rc;
155
156         if (end > nr_minors) {
157                 unsigned long *bitmap, *old;
158
159                 bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
160                                  GFP_KERNEL);
161                 if (bitmap == NULL)
162                         return -ENOMEM;
163
164                 spin_lock(&minor_lock);
165                 if (end > nr_minors) {
166                         old = minors;
167                         memcpy(bitmap, minors,
168                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
169                         minors = bitmap;
170                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
171                 } else
172                         old = bitmap;
173                 spin_unlock(&minor_lock);
174                 kfree(old);
175         }
176
177         spin_lock(&minor_lock);
178         if (find_next_bit(minors, end, minor) >= end) {
179                 for (; minor < end; ++minor)
180                         __set_bit(minor, minors);
181                 rc = 0;
182         } else
183                 rc = -EBUSY;
184         spin_unlock(&minor_lock);
185
186         return rc;
187 }
188
189 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
190 {
191         unsigned int end = minor + nr;
192
193         BUG_ON(end > nr_minors);
194         spin_lock(&minor_lock);
195         for (; minor < end; ++minor)
196                 __clear_bit(minor, minors);
197         spin_unlock(&minor_lock);
198 }
199
200 static void blkif_restart_queue_callback(void *arg)
201 {
202         struct blkfront_info *info = (struct blkfront_info *)arg;
203         schedule_work(&info->work);
204 }
205
206 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
207 {
208         /* We don't have real geometry info, but let's at least return
209            values consistent with the size of the device */
210         sector_t nsect = get_capacity(bd->bd_disk);
211         sector_t cylinders = nsect;
212
213         hg->heads = 0xff;
214         hg->sectors = 0x3f;
215         sector_div(cylinders, hg->heads * hg->sectors);
216         hg->cylinders = cylinders;
217         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
218                 hg->cylinders = 0xffff;
219         return 0;
220 }
221
222 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
223                        unsigned command, unsigned long argument)
224 {
225         struct blkfront_info *info = bdev->bd_disk->private_data;
226         int i;
227
228         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
229                 command, (long)argument);
230
231         switch (command) {
232         case CDROMMULTISESSION:
233                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
234                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
235                         if (put_user(0, (char __user *)(argument + i)))
236                                 return -EFAULT;
237                 return 0;
238
239         case CDROM_GET_CAPABILITY: {
240                 struct gendisk *gd = info->gd;
241                 if (gd->flags & GENHD_FL_CD)
242                         return 0;
243                 return -EINVAL;
244         }
245
246         default:
247                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
248                   command);*/
249                 return -EINVAL; /* same return as native Linux */
250         }
251
252         return 0;
253 }
254
255 /*
256  * Generate a Xen blkfront IO request from a blk layer request.  Reads
257  * and writes are handled as expected.
258  *
259  * @req: a request struct
260  */
261 static int blkif_queue_request(struct request *req)
262 {
263         struct blkfront_info *info = req->rq_disk->private_data;
264         unsigned long buffer_mfn;
265         struct blkif_request *ring_req;
266         unsigned long id;
267         unsigned int fsect, lsect;
268         int i, ref;
269         grant_ref_t gref_head;
270         struct scatterlist *sg;
271
272         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
273                 return 1;
274
275         if (gnttab_alloc_grant_references(
276                 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
277                 gnttab_request_free_callback(
278                         &info->callback,
279                         blkif_restart_queue_callback,
280                         info,
281                         BLKIF_MAX_SEGMENTS_PER_REQUEST);
282                 return 1;
283         }
284
285         /* Fill out a communications ring structure. */
286         ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
287         id = get_id_from_freelist(info);
288         info->shadow[id].request = req;
289
290         ring_req->id = id;
291         ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
292         ring_req->handle = info->handle;
293
294         ring_req->operation = rq_data_dir(req) ?
295                 BLKIF_OP_WRITE : BLKIF_OP_READ;
296
297         if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
298                 /*
299                  * Ideally we can do an unordered flush-to-disk. In case the
300                  * backend onlysupports barriers, use that. A barrier request
301                  * a superset of FUA, so we can implement it the same
302                  * way.  (It's also a FLUSH+FUA, since it is
303                  * guaranteed ordered WRT previous writes.)
304                  */
305                 ring_req->operation = info->flush_op;
306         }
307
308         if (unlikely(req->cmd_flags & REQ_DISCARD)) {
309                 /* id, sector_number and handle are set above. */
310                 ring_req->operation = BLKIF_OP_DISCARD;
311                 ring_req->nr_segments = 0;
312                 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
313         } else {
314                 ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
315                 BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
316
317                 for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
318                         buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
319                         fsect = sg->offset >> 9;
320                         lsect = fsect + (sg->length >> 9) - 1;
321                         /* install a grant reference. */
322                         ref = gnttab_claim_grant_reference(&gref_head);
323                         BUG_ON(ref == -ENOSPC);
324
325                         gnttab_grant_foreign_access_ref(
326                                         ref,
327                                         info->xbdev->otherend_id,
328                                         buffer_mfn,
329                                         rq_data_dir(req));
330
331                         info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
332                         ring_req->u.rw.seg[i] =
333                                         (struct blkif_request_segment) {
334                                                 .gref       = ref,
335                                                 .first_sect = fsect,
336                                                 .last_sect  = lsect };
337                 }
338         }
339
340         info->ring.req_prod_pvt++;
341
342         /* Keep a private copy so we can reissue requests when recovering. */
343         info->shadow[id].req = *ring_req;
344
345         gnttab_free_grant_references(gref_head);
346
347         return 0;
348 }
349
350
351 static inline void flush_requests(struct blkfront_info *info)
352 {
353         int notify;
354
355         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
356
357         if (notify)
358                 notify_remote_via_irq(info->irq);
359 }
360
361 /*
362  * do_blkif_request
363  *  read a block; request is in a request queue
364  */
365 static void do_blkif_request(struct request_queue *rq)
366 {
367         struct blkfront_info *info = NULL;
368         struct request *req;
369         int queued;
370
371         pr_debug("Entered do_blkif_request\n");
372
373         queued = 0;
374
375         while ((req = blk_peek_request(rq)) != NULL) {
376                 info = req->rq_disk->private_data;
377
378                 if (RING_FULL(&info->ring))
379                         goto wait;
380
381                 blk_start_request(req);
382
383                 if ((req->cmd_type != REQ_TYPE_FS) ||
384                     ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) &&
385                     !info->flush_op)) {
386                         __blk_end_request_all(req, -EIO);
387                         continue;
388                 }
389
390                 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
391                          "(%u/%u) buffer:%p [%s]\n",
392                          req, req->cmd, (unsigned long)blk_rq_pos(req),
393                          blk_rq_cur_sectors(req), blk_rq_sectors(req),
394                          req->buffer, rq_data_dir(req) ? "write" : "read");
395
396                 if (blkif_queue_request(req)) {
397                         blk_requeue_request(rq, req);
398 wait:
399                         /* Avoid pointless unplugs. */
400                         blk_stop_queue(rq);
401                         break;
402                 }
403
404                 queued++;
405         }
406
407         if (queued != 0)
408                 flush_requests(info);
409 }
410
411 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
412 {
413         struct request_queue *rq;
414         struct blkfront_info *info = gd->private_data;
415
416         rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
417         if (rq == NULL)
418                 return -1;
419
420         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
421
422         if (info->feature_discard) {
423                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
424                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
425                 rq->limits.discard_granularity = info->discard_granularity;
426                 rq->limits.discard_alignment = info->discard_alignment;
427         }
428
429         /* Hard sector size and max sectors impersonate the equiv. hardware. */
430         blk_queue_logical_block_size(rq, sector_size);
431         blk_queue_max_hw_sectors(rq, 512);
432
433         /* Each segment in a request is up to an aligned page in size. */
434         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
435         blk_queue_max_segment_size(rq, PAGE_SIZE);
436
437         /* Ensure a merged request will fit in a single I/O ring slot. */
438         blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
439
440         /* Make sure buffer addresses are sector-aligned. */
441         blk_queue_dma_alignment(rq, 511);
442
443         /* Make sure we don't use bounce buffers. */
444         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
445
446         gd->queue = rq;
447
448         return 0;
449 }
450
451
452 static void xlvbd_flush(struct blkfront_info *info)
453 {
454         blk_queue_flush(info->rq, info->feature_flush);
455         printk(KERN_INFO "blkfront: %s: %s: %s\n",
456                info->gd->disk_name,
457                info->flush_op == BLKIF_OP_WRITE_BARRIER ?
458                 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
459                 "flush diskcache" : "barrier or flush"),
460                info->feature_flush ? "enabled" : "disabled");
461 }
462
463 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
464 {
465         int major;
466         major = BLKIF_MAJOR(vdevice);
467         *minor = BLKIF_MINOR(vdevice);
468         switch (major) {
469                 case XEN_IDE0_MAJOR:
470                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
471                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
472                                 EMULATED_HD_DISK_MINOR_OFFSET;
473                         break;
474                 case XEN_IDE1_MAJOR:
475                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
476                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
477                                 EMULATED_HD_DISK_MINOR_OFFSET;
478                         break;
479                 case XEN_SCSI_DISK0_MAJOR:
480                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
481                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
482                         break;
483                 case XEN_SCSI_DISK1_MAJOR:
484                 case XEN_SCSI_DISK2_MAJOR:
485                 case XEN_SCSI_DISK3_MAJOR:
486                 case XEN_SCSI_DISK4_MAJOR:
487                 case XEN_SCSI_DISK5_MAJOR:
488                 case XEN_SCSI_DISK6_MAJOR:
489                 case XEN_SCSI_DISK7_MAJOR:
490                         *offset = (*minor / PARTS_PER_DISK) + 
491                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
492                                 EMULATED_SD_DISK_NAME_OFFSET;
493                         *minor = *minor +
494                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
495                                 EMULATED_SD_DISK_MINOR_OFFSET;
496                         break;
497                 case XEN_SCSI_DISK8_MAJOR:
498                 case XEN_SCSI_DISK9_MAJOR:
499                 case XEN_SCSI_DISK10_MAJOR:
500                 case XEN_SCSI_DISK11_MAJOR:
501                 case XEN_SCSI_DISK12_MAJOR:
502                 case XEN_SCSI_DISK13_MAJOR:
503                 case XEN_SCSI_DISK14_MAJOR:
504                 case XEN_SCSI_DISK15_MAJOR:
505                         *offset = (*minor / PARTS_PER_DISK) + 
506                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
507                                 EMULATED_SD_DISK_NAME_OFFSET;
508                         *minor = *minor +
509                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
510                                 EMULATED_SD_DISK_MINOR_OFFSET;
511                         break;
512                 case XENVBD_MAJOR:
513                         *offset = *minor / PARTS_PER_DISK;
514                         break;
515                 default:
516                         printk(KERN_WARNING "blkfront: your disk configuration is "
517                                         "incorrect, please use an xvd device instead\n");
518                         return -ENODEV;
519         }
520         return 0;
521 }
522
523 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
524                                struct blkfront_info *info,
525                                u16 vdisk_info, u16 sector_size)
526 {
527         struct gendisk *gd;
528         int nr_minors = 1;
529         int err;
530         unsigned int offset;
531         int minor;
532         int nr_parts;
533
534         BUG_ON(info->gd != NULL);
535         BUG_ON(info->rq != NULL);
536
537         if ((info->vdevice>>EXT_SHIFT) > 1) {
538                 /* this is above the extended range; something is wrong */
539                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
540                 return -ENODEV;
541         }
542
543         if (!VDEV_IS_EXTENDED(info->vdevice)) {
544                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
545                 if (err)
546                         return err;             
547                 nr_parts = PARTS_PER_DISK;
548         } else {
549                 minor = BLKIF_MINOR_EXT(info->vdevice);
550                 nr_parts = PARTS_PER_EXT_DISK;
551                 offset = minor / nr_parts;
552                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
553                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
554                                         "emulated IDE disks,\n\t choose an xvd device name"
555                                         "from xvde on\n", info->vdevice);
556         }
557         err = -ENODEV;
558
559         if ((minor % nr_parts) == 0)
560                 nr_minors = nr_parts;
561
562         err = xlbd_reserve_minors(minor, nr_minors);
563         if (err)
564                 goto out;
565         err = -ENODEV;
566
567         gd = alloc_disk(nr_minors);
568         if (gd == NULL)
569                 goto release;
570
571         if (nr_minors > 1) {
572                 if (offset < 26)
573                         sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
574                 else
575                         sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
576                                 'a' + ((offset / 26)-1), 'a' + (offset % 26));
577         } else {
578                 if (offset < 26)
579                         sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
580                                 'a' + offset,
581                                 minor & (nr_parts - 1));
582                 else
583                         sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
584                                 'a' + ((offset / 26) - 1),
585                                 'a' + (offset % 26),
586                                 minor & (nr_parts - 1));
587         }
588
589         gd->major = XENVBD_MAJOR;
590         gd->first_minor = minor;
591         gd->fops = &xlvbd_block_fops;
592         gd->private_data = info;
593         gd->driverfs_dev = &(info->xbdev->dev);
594         set_capacity(gd, capacity);
595
596         if (xlvbd_init_blk_queue(gd, sector_size)) {
597                 del_gendisk(gd);
598                 goto release;
599         }
600
601         info->rq = gd->queue;
602         info->gd = gd;
603
604         xlvbd_flush(info);
605
606         if (vdisk_info & VDISK_READONLY)
607                 set_disk_ro(gd, 1);
608
609         if (vdisk_info & VDISK_REMOVABLE)
610                 gd->flags |= GENHD_FL_REMOVABLE;
611
612         if (vdisk_info & VDISK_CDROM)
613                 gd->flags |= GENHD_FL_CD;
614
615         return 0;
616
617  release:
618         xlbd_release_minors(minor, nr_minors);
619  out:
620         return err;
621 }
622
623 static void xlvbd_release_gendisk(struct blkfront_info *info)
624 {
625         unsigned int minor, nr_minors;
626         unsigned long flags;
627
628         if (info->rq == NULL)
629                 return;
630
631         spin_lock_irqsave(&blkif_io_lock, flags);
632
633         /* No more blkif_request(). */
634         blk_stop_queue(info->rq);
635
636         /* No more gnttab callback work. */
637         gnttab_cancel_free_callback(&info->callback);
638         spin_unlock_irqrestore(&blkif_io_lock, flags);
639
640         /* Flush gnttab callback work. Must be done with no locks held. */
641         flush_work_sync(&info->work);
642
643         del_gendisk(info->gd);
644
645         minor = info->gd->first_minor;
646         nr_minors = info->gd->minors;
647         xlbd_release_minors(minor, nr_minors);
648
649         blk_cleanup_queue(info->rq);
650         info->rq = NULL;
651
652         put_disk(info->gd);
653         info->gd = NULL;
654 }
655
656 static void kick_pending_request_queues(struct blkfront_info *info)
657 {
658         if (!RING_FULL(&info->ring)) {
659                 /* Re-enable calldowns. */
660                 blk_start_queue(info->rq);
661                 /* Kick things off immediately. */
662                 do_blkif_request(info->rq);
663         }
664 }
665
666 static void blkif_restart_queue(struct work_struct *work)
667 {
668         struct blkfront_info *info = container_of(work, struct blkfront_info, work);
669
670         spin_lock_irq(&blkif_io_lock);
671         if (info->connected == BLKIF_STATE_CONNECTED)
672                 kick_pending_request_queues(info);
673         spin_unlock_irq(&blkif_io_lock);
674 }
675
676 static void blkif_free(struct blkfront_info *info, int suspend)
677 {
678         /* Prevent new requests being issued until we fix things up. */
679         spin_lock_irq(&blkif_io_lock);
680         info->connected = suspend ?
681                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
682         /* No more blkif_request(). */
683         if (info->rq)
684                 blk_stop_queue(info->rq);
685         /* No more gnttab callback work. */
686         gnttab_cancel_free_callback(&info->callback);
687         spin_unlock_irq(&blkif_io_lock);
688
689         /* Flush gnttab callback work. Must be done with no locks held. */
690         flush_work_sync(&info->work);
691
692         /* Free resources associated with old device channel. */
693         if (info->ring_ref != GRANT_INVALID_REF) {
694                 gnttab_end_foreign_access(info->ring_ref, 0,
695                                           (unsigned long)info->ring.sring);
696                 info->ring_ref = GRANT_INVALID_REF;
697                 info->ring.sring = NULL;
698         }
699         if (info->irq)
700                 unbind_from_irqhandler(info->irq, info);
701         info->evtchn = info->irq = 0;
702
703 }
704
705 static void blkif_completion(struct blk_shadow *s)
706 {
707         int i;
708         for (i = 0; i < s->req.nr_segments; i++)
709                 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
710 }
711
712 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
713 {
714         struct request *req;
715         struct blkif_response *bret;
716         RING_IDX i, rp;
717         unsigned long flags;
718         struct blkfront_info *info = (struct blkfront_info *)dev_id;
719         int error;
720
721         spin_lock_irqsave(&blkif_io_lock, flags);
722
723         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
724                 spin_unlock_irqrestore(&blkif_io_lock, flags);
725                 return IRQ_HANDLED;
726         }
727
728  again:
729         rp = info->ring.sring->rsp_prod;
730         rmb(); /* Ensure we see queued responses up to 'rp'. */
731
732         for (i = info->ring.rsp_cons; i != rp; i++) {
733                 unsigned long id;
734
735                 bret = RING_GET_RESPONSE(&info->ring, i);
736                 id   = bret->id;
737                 req  = info->shadow[id].request;
738
739                 blkif_completion(&info->shadow[id]);
740
741                 add_id_to_freelist(info, id);
742
743                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
744                 switch (bret->operation) {
745                 case BLKIF_OP_DISCARD:
746                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
747                                 struct request_queue *rq = info->rq;
748                                 printk(KERN_WARNING "blkfront: %s: discard op failed\n",
749                                            info->gd->disk_name);
750                                 error = -EOPNOTSUPP;
751                                 info->feature_discard = 0;
752                                 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
753                         }
754                         __blk_end_request_all(req, error);
755                         break;
756                 case BLKIF_OP_FLUSH_DISKCACHE:
757                 case BLKIF_OP_WRITE_BARRIER:
758                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
759                                 printk(KERN_WARNING "blkfront: %s: write %s op failed\n",
760                                        info->flush_op == BLKIF_OP_WRITE_BARRIER ?
761                                        "barrier" :  "flush disk cache",
762                                        info->gd->disk_name);
763                                 error = -EOPNOTSUPP;
764                         }
765                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
766                                      info->shadow[id].req.nr_segments == 0)) {
767                                 printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
768                                        info->flush_op == BLKIF_OP_WRITE_BARRIER ?
769                                        "barrier" :  "flush disk cache",
770                                        info->gd->disk_name);
771                                 error = -EOPNOTSUPP;
772                         }
773                         if (unlikely(error)) {
774                                 if (error == -EOPNOTSUPP)
775                                         error = 0;
776                                 info->feature_flush = 0;
777                                 info->flush_op = 0;
778                                 xlvbd_flush(info);
779                         }
780                         /* fall through */
781                 case BLKIF_OP_READ:
782                 case BLKIF_OP_WRITE:
783                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
784                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
785                                         "request: %x\n", bret->status);
786
787                         __blk_end_request_all(req, error);
788                         break;
789                 default:
790                         BUG();
791                 }
792         }
793
794         info->ring.rsp_cons = i;
795
796         if (i != info->ring.req_prod_pvt) {
797                 int more_to_do;
798                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
799                 if (more_to_do)
800                         goto again;
801         } else
802                 info->ring.sring->rsp_event = i + 1;
803
804         kick_pending_request_queues(info);
805
806         spin_unlock_irqrestore(&blkif_io_lock, flags);
807
808         return IRQ_HANDLED;
809 }
810
811
812 static int setup_blkring(struct xenbus_device *dev,
813                          struct blkfront_info *info)
814 {
815         struct blkif_sring *sring;
816         int err;
817
818         info->ring_ref = GRANT_INVALID_REF;
819
820         sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
821         if (!sring) {
822                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
823                 return -ENOMEM;
824         }
825         SHARED_RING_INIT(sring);
826         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
827
828         sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
829
830         err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
831         if (err < 0) {
832                 free_page((unsigned long)sring);
833                 info->ring.sring = NULL;
834                 goto fail;
835         }
836         info->ring_ref = err;
837
838         err = xenbus_alloc_evtchn(dev, &info->evtchn);
839         if (err)
840                 goto fail;
841
842         err = bind_evtchn_to_irqhandler(info->evtchn,
843                                         blkif_interrupt,
844                                         IRQF_SAMPLE_RANDOM, "blkif", info);
845         if (err <= 0) {
846                 xenbus_dev_fatal(dev, err,
847                                  "bind_evtchn_to_irqhandler failed");
848                 goto fail;
849         }
850         info->irq = err;
851
852         return 0;
853 fail:
854         blkif_free(info, 0);
855         return err;
856 }
857
858
859 /* Common code used when first setting up, and when resuming. */
860 static int talk_to_blkback(struct xenbus_device *dev,
861                            struct blkfront_info *info)
862 {
863         const char *message = NULL;
864         struct xenbus_transaction xbt;
865         int err;
866
867         /* Create shared ring, alloc event channel. */
868         err = setup_blkring(dev, info);
869         if (err)
870                 goto out;
871
872 again:
873         err = xenbus_transaction_start(&xbt);
874         if (err) {
875                 xenbus_dev_fatal(dev, err, "starting transaction");
876                 goto destroy_blkring;
877         }
878
879         err = xenbus_printf(xbt, dev->nodename,
880                             "ring-ref", "%u", info->ring_ref);
881         if (err) {
882                 message = "writing ring-ref";
883                 goto abort_transaction;
884         }
885         err = xenbus_printf(xbt, dev->nodename,
886                             "event-channel", "%u", info->evtchn);
887         if (err) {
888                 message = "writing event-channel";
889                 goto abort_transaction;
890         }
891         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
892                             XEN_IO_PROTO_ABI_NATIVE);
893         if (err) {
894                 message = "writing protocol";
895                 goto abort_transaction;
896         }
897
898         err = xenbus_transaction_end(xbt, 0);
899         if (err) {
900                 if (err == -EAGAIN)
901                         goto again;
902                 xenbus_dev_fatal(dev, err, "completing transaction");
903                 goto destroy_blkring;
904         }
905
906         xenbus_switch_state(dev, XenbusStateInitialised);
907
908         return 0;
909
910  abort_transaction:
911         xenbus_transaction_end(xbt, 1);
912         if (message)
913                 xenbus_dev_fatal(dev, err, "%s", message);
914  destroy_blkring:
915         blkif_free(info, 0);
916  out:
917         return err;
918 }
919
920 /**
921  * Entry point to this code when a new device is created.  Allocate the basic
922  * structures and the ring buffer for communication with the backend, and
923  * inform the backend of the appropriate details for those.  Switch to
924  * Initialised state.
925  */
926 static int blkfront_probe(struct xenbus_device *dev,
927                           const struct xenbus_device_id *id)
928 {
929         int err, vdevice, i;
930         struct blkfront_info *info;
931
932         /* FIXME: Use dynamic device id if this is not set. */
933         err = xenbus_scanf(XBT_NIL, dev->nodename,
934                            "virtual-device", "%i", &vdevice);
935         if (err != 1) {
936                 /* go looking in the extended area instead */
937                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
938                                    "%i", &vdevice);
939                 if (err != 1) {
940                         xenbus_dev_fatal(dev, err, "reading virtual-device");
941                         return err;
942                 }
943         }
944
945         if (xen_hvm_domain()) {
946                 char *type;
947                 int len;
948                 /* no unplug has been done: do not hook devices != xen vbds */
949                 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
950                         int major;
951
952                         if (!VDEV_IS_EXTENDED(vdevice))
953                                 major = BLKIF_MAJOR(vdevice);
954                         else
955                                 major = XENVBD_MAJOR;
956
957                         if (major != XENVBD_MAJOR) {
958                                 printk(KERN_INFO
959                                                 "%s: HVM does not support vbd %d as xen block device\n",
960                                                 __FUNCTION__, vdevice);
961                                 return -ENODEV;
962                         }
963                 }
964                 /* do not create a PV cdrom device if we are an HVM guest */
965                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
966                 if (IS_ERR(type))
967                         return -ENODEV;
968                 if (strncmp(type, "cdrom", 5) == 0) {
969                         kfree(type);
970                         return -ENODEV;
971                 }
972                 kfree(type);
973         }
974         info = kzalloc(sizeof(*info), GFP_KERNEL);
975         if (!info) {
976                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
977                 return -ENOMEM;
978         }
979
980         mutex_init(&info->mutex);
981         info->xbdev = dev;
982         info->vdevice = vdevice;
983         info->connected = BLKIF_STATE_DISCONNECTED;
984         INIT_WORK(&info->work, blkif_restart_queue);
985
986         for (i = 0; i < BLK_RING_SIZE; i++)
987                 info->shadow[i].req.id = i+1;
988         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
989
990         /* Front end dir is a number, which is used as the id. */
991         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
992         dev_set_drvdata(&dev->dev, info);
993
994         err = talk_to_blkback(dev, info);
995         if (err) {
996                 kfree(info);
997                 dev_set_drvdata(&dev->dev, NULL);
998                 return err;
999         }
1000
1001         return 0;
1002 }
1003
1004
1005 static int blkif_recover(struct blkfront_info *info)
1006 {
1007         int i;
1008         struct blkif_request *req;
1009         struct blk_shadow *copy;
1010         int j;
1011
1012         /* Stage 1: Make a safe copy of the shadow state. */
1013         copy = kmalloc(sizeof(info->shadow),
1014                        GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1015         if (!copy)
1016                 return -ENOMEM;
1017         memcpy(copy, info->shadow, sizeof(info->shadow));
1018
1019         /* Stage 2: Set up free list. */
1020         memset(&info->shadow, 0, sizeof(info->shadow));
1021         for (i = 0; i < BLK_RING_SIZE; i++)
1022                 info->shadow[i].req.id = i+1;
1023         info->shadow_free = info->ring.req_prod_pvt;
1024         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
1025
1026         /* Stage 3: Find pending requests and requeue them. */
1027         for (i = 0; i < BLK_RING_SIZE; i++) {
1028                 /* Not in use? */
1029                 if (!copy[i].request)
1030                         continue;
1031
1032                 /* Grab a request slot and copy shadow state into it. */
1033                 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
1034                 *req = copy[i].req;
1035
1036                 /* We get a new request id, and must reset the shadow state. */
1037                 req->id = get_id_from_freelist(info);
1038                 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
1039
1040                 /* Rewrite any grant references invalidated by susp/resume. */
1041                 for (j = 0; j < req->nr_segments; j++)
1042                         gnttab_grant_foreign_access_ref(
1043                                 req->u.rw.seg[j].gref,
1044                                 info->xbdev->otherend_id,
1045                                 pfn_to_mfn(info->shadow[req->id].frame[j]),
1046                                 rq_data_dir(info->shadow[req->id].request));
1047                 info->shadow[req->id].req = *req;
1048
1049                 info->ring.req_prod_pvt++;
1050         }
1051
1052         kfree(copy);
1053
1054         xenbus_switch_state(info->xbdev, XenbusStateConnected);
1055
1056         spin_lock_irq(&blkif_io_lock);
1057
1058         /* Now safe for us to use the shared ring */
1059         info->connected = BLKIF_STATE_CONNECTED;
1060
1061         /* Send off requeued requests */
1062         flush_requests(info);
1063
1064         /* Kick any other new requests queued since we resumed */
1065         kick_pending_request_queues(info);
1066
1067         spin_unlock_irq(&blkif_io_lock);
1068
1069         return 0;
1070 }
1071
1072 /**
1073  * We are reconnecting to the backend, due to a suspend/resume, or a backend
1074  * driver restart.  We tear down our blkif structure and recreate it, but
1075  * leave the device-layer structures intact so that this is transparent to the
1076  * rest of the kernel.
1077  */
1078 static int blkfront_resume(struct xenbus_device *dev)
1079 {
1080         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1081         int err;
1082
1083         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1084
1085         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1086
1087         err = talk_to_blkback(dev, info);
1088         if (info->connected == BLKIF_STATE_SUSPENDED && !err)
1089                 err = blkif_recover(info);
1090
1091         return err;
1092 }
1093
1094 static void
1095 blkfront_closing(struct blkfront_info *info)
1096 {
1097         struct xenbus_device *xbdev = info->xbdev;
1098         struct block_device *bdev = NULL;
1099
1100         mutex_lock(&info->mutex);
1101
1102         if (xbdev->state == XenbusStateClosing) {
1103                 mutex_unlock(&info->mutex);
1104                 return;
1105         }
1106
1107         if (info->gd)
1108                 bdev = bdget_disk(info->gd, 0);
1109
1110         mutex_unlock(&info->mutex);
1111
1112         if (!bdev) {
1113                 xenbus_frontend_closed(xbdev);
1114                 return;
1115         }
1116
1117         mutex_lock(&bdev->bd_mutex);
1118
1119         if (bdev->bd_openers) {
1120                 xenbus_dev_error(xbdev, -EBUSY,
1121                                  "Device in use; refusing to close");
1122                 xenbus_switch_state(xbdev, XenbusStateClosing);
1123         } else {
1124                 xlvbd_release_gendisk(info);
1125                 xenbus_frontend_closed(xbdev);
1126         }
1127
1128         mutex_unlock(&bdev->bd_mutex);
1129         bdput(bdev);
1130 }
1131
1132 static void blkfront_setup_discard(struct blkfront_info *info)
1133 {
1134         int err;
1135         char *type;
1136         unsigned int discard_granularity;
1137         unsigned int discard_alignment;
1138
1139         type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
1140         if (IS_ERR(type))
1141                 return;
1142
1143         if (strncmp(type, "phy", 3) == 0) {
1144                 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1145                         "discard-granularity", "%u", &discard_granularity,
1146                         "discard-alignment", "%u", &discard_alignment,
1147                         NULL);
1148                 if (!err) {
1149                         info->feature_discard = 1;
1150                         info->discard_granularity = discard_granularity;
1151                         info->discard_alignment = discard_alignment;
1152                 }
1153         } else if (strncmp(type, "file", 4) == 0)
1154                 info->feature_discard = 1;
1155
1156         kfree(type);
1157 }
1158
1159 /*
1160  * Invoked when the backend is finally 'ready' (and has told produced
1161  * the details about the physical device - #sectors, size, etc).
1162  */
1163 static void blkfront_connect(struct blkfront_info *info)
1164 {
1165         unsigned long long sectors;
1166         unsigned long sector_size;
1167         unsigned int binfo;
1168         int err;
1169         int barrier, flush, discard;
1170
1171         switch (info->connected) {
1172         case BLKIF_STATE_CONNECTED:
1173                 /*
1174                  * Potentially, the back-end may be signalling
1175                  * a capacity change; update the capacity.
1176                  */
1177                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1178                                    "sectors", "%Lu", &sectors);
1179                 if (XENBUS_EXIST_ERR(err))
1180                         return;
1181                 printk(KERN_INFO "Setting capacity to %Lu\n",
1182                        sectors);
1183                 set_capacity(info->gd, sectors);
1184                 revalidate_disk(info->gd);
1185
1186                 /* fall through */
1187         case BLKIF_STATE_SUSPENDED:
1188                 return;
1189
1190         default:
1191                 break;
1192         }
1193
1194         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1195                 __func__, info->xbdev->otherend);
1196
1197         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1198                             "sectors", "%llu", &sectors,
1199                             "info", "%u", &binfo,
1200                             "sector-size", "%lu", &sector_size,
1201                             NULL);
1202         if (err) {
1203                 xenbus_dev_fatal(info->xbdev, err,
1204                                  "reading backend fields at %s",
1205                                  info->xbdev->otherend);
1206                 return;
1207         }
1208
1209         info->feature_flush = 0;
1210         info->flush_op = 0;
1211
1212         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1213                             "feature-barrier", "%d", &barrier,
1214                             NULL);
1215
1216         /*
1217          * If there's no "feature-barrier" defined, then it means
1218          * we're dealing with a very old backend which writes
1219          * synchronously; nothing to do.
1220          *
1221          * If there are barriers, then we use flush.
1222          */
1223         if (!err && barrier) {
1224                 info->feature_flush = REQ_FLUSH | REQ_FUA;
1225                 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1226         }
1227         /*
1228          * And if there is "feature-flush-cache" use that above
1229          * barriers.
1230          */
1231         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1232                             "feature-flush-cache", "%d", &flush,
1233                             NULL);
1234
1235         if (!err && flush) {
1236                 info->feature_flush = REQ_FLUSH;
1237                 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1238         }
1239
1240         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1241                             "feature-discard", "%d", &discard,
1242                             NULL);
1243
1244         if (!err && discard)
1245                 blkfront_setup_discard(info);
1246
1247         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1248         if (err) {
1249                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1250                                  info->xbdev->otherend);
1251                 return;
1252         }
1253
1254         xenbus_switch_state(info->xbdev, XenbusStateConnected);
1255
1256         /* Kick pending requests. */
1257         spin_lock_irq(&blkif_io_lock);
1258         info->connected = BLKIF_STATE_CONNECTED;
1259         kick_pending_request_queues(info);
1260         spin_unlock_irq(&blkif_io_lock);
1261
1262         add_disk(info->gd);
1263
1264         info->is_ready = 1;
1265 }
1266
1267 /**
1268  * Callback received when the backend's state changes.
1269  */
1270 static void blkback_changed(struct xenbus_device *dev,
1271                             enum xenbus_state backend_state)
1272 {
1273         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1274
1275         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1276
1277         switch (backend_state) {
1278         case XenbusStateInitialising:
1279         case XenbusStateInitWait:
1280         case XenbusStateInitialised:
1281         case XenbusStateReconfiguring:
1282         case XenbusStateReconfigured:
1283         case XenbusStateUnknown:
1284         case XenbusStateClosed:
1285                 break;
1286
1287         case XenbusStateConnected:
1288                 blkfront_connect(info);
1289                 break;
1290
1291         case XenbusStateClosing:
1292                 blkfront_closing(info);
1293                 break;
1294         }
1295 }
1296
1297 static int blkfront_remove(struct xenbus_device *xbdev)
1298 {
1299         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1300         struct block_device *bdev = NULL;
1301         struct gendisk *disk;
1302
1303         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1304
1305         blkif_free(info, 0);
1306
1307         mutex_lock(&info->mutex);
1308
1309         disk = info->gd;
1310         if (disk)
1311                 bdev = bdget_disk(disk, 0);
1312
1313         info->xbdev = NULL;
1314         mutex_unlock(&info->mutex);
1315
1316         if (!bdev) {
1317                 kfree(info);
1318                 return 0;
1319         }
1320
1321         /*
1322          * The xbdev was removed before we reached the Closed
1323          * state. See if it's safe to remove the disk. If the bdev
1324          * isn't closed yet, we let release take care of it.
1325          */
1326
1327         mutex_lock(&bdev->bd_mutex);
1328         info = disk->private_data;
1329
1330         dev_warn(disk_to_dev(disk),
1331                  "%s was hot-unplugged, %d stale handles\n",
1332                  xbdev->nodename, bdev->bd_openers);
1333
1334         if (info && !bdev->bd_openers) {
1335                 xlvbd_release_gendisk(info);
1336                 disk->private_data = NULL;
1337                 kfree(info);
1338         }
1339
1340         mutex_unlock(&bdev->bd_mutex);
1341         bdput(bdev);
1342
1343         return 0;
1344 }
1345
1346 static int blkfront_is_ready(struct xenbus_device *dev)
1347 {
1348         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1349
1350         return info->is_ready && info->xbdev;
1351 }
1352
1353 static int blkif_open(struct block_device *bdev, fmode_t mode)
1354 {
1355         struct gendisk *disk = bdev->bd_disk;
1356         struct blkfront_info *info;
1357         int err = 0;
1358
1359         mutex_lock(&blkfront_mutex);
1360
1361         info = disk->private_data;
1362         if (!info) {
1363                 /* xbdev gone */
1364                 err = -ERESTARTSYS;
1365                 goto out;
1366         }
1367
1368         mutex_lock(&info->mutex);
1369
1370         if (!info->gd)
1371                 /* xbdev is closed */
1372                 err = -ERESTARTSYS;
1373
1374         mutex_unlock(&info->mutex);
1375
1376 out:
1377         mutex_unlock(&blkfront_mutex);
1378         return err;
1379 }
1380
1381 static int blkif_release(struct gendisk *disk, fmode_t mode)
1382 {
1383         struct blkfront_info *info = disk->private_data;
1384         struct block_device *bdev;
1385         struct xenbus_device *xbdev;
1386
1387         mutex_lock(&blkfront_mutex);
1388
1389         bdev = bdget_disk(disk, 0);
1390         bdput(bdev);
1391
1392         if (bdev->bd_openers)
1393                 goto out;
1394
1395         /*
1396          * Check if we have been instructed to close. We will have
1397          * deferred this request, because the bdev was still open.
1398          */
1399
1400         mutex_lock(&info->mutex);
1401         xbdev = info->xbdev;
1402
1403         if (xbdev && xbdev->state == XenbusStateClosing) {
1404                 /* pending switch to state closed */
1405                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1406                 xlvbd_release_gendisk(info);
1407                 xenbus_frontend_closed(info->xbdev);
1408         }
1409
1410         mutex_unlock(&info->mutex);
1411
1412         if (!xbdev) {
1413                 /* sudden device removal */
1414                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1415                 xlvbd_release_gendisk(info);
1416                 disk->private_data = NULL;
1417                 kfree(info);
1418         }
1419
1420 out:
1421         mutex_unlock(&blkfront_mutex);
1422         return 0;
1423 }
1424
1425 static const struct block_device_operations xlvbd_block_fops =
1426 {
1427         .owner = THIS_MODULE,
1428         .open = blkif_open,
1429         .release = blkif_release,
1430         .getgeo = blkif_getgeo,
1431         .ioctl = blkif_ioctl,
1432 };
1433
1434
1435 static const struct xenbus_device_id blkfront_ids[] = {
1436         { "vbd" },
1437         { "" }
1438 };
1439
1440 static DEFINE_XENBUS_DRIVER(blkfront, ,
1441         .probe = blkfront_probe,
1442         .remove = blkfront_remove,
1443         .resume = blkfront_resume,
1444         .otherend_changed = blkback_changed,
1445         .is_ready = blkfront_is_ready,
1446 );
1447
1448 static int __init xlblk_init(void)
1449 {
1450         int ret;
1451
1452         if (!xen_domain())
1453                 return -ENODEV;
1454
1455         if (!xen_platform_pci_unplug)
1456                 return -ENODEV;
1457
1458         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1459                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1460                        XENVBD_MAJOR, DEV_NAME);
1461                 return -ENODEV;
1462         }
1463
1464         ret = xenbus_register_frontend(&blkfront_driver);
1465         if (ret) {
1466                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
1467                 return ret;
1468         }
1469
1470         return 0;
1471 }
1472 module_init(xlblk_init);
1473
1474
1475 static void __exit xlblk_exit(void)
1476 {
1477         return xenbus_unregister_driver(&blkfront_driver);
1478 }
1479 module_exit(xlblk_exit);
1480
1481 MODULE_DESCRIPTION("Xen virtual block device frontend");
1482 MODULE_LICENSE("GPL");
1483 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1484 MODULE_ALIAS("xen:vbd");
1485 MODULE_ALIAS("xenblk");