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 #include <linux/bitmap.h>
47
48 #include <xen/xen.h>
49 #include <xen/xenbus.h>
50 #include <xen/grant_table.h>
51 #include <xen/events.h>
52 #include <xen/page.h>
53 #include <xen/platform_pci.h>
54
55 #include <xen/interface/grant_table.h>
56 #include <xen/interface/io/blkif.h>
57 #include <xen/interface/io/protocols.h>
58
59 #include <asm/xen/hypervisor.h>
60
61 enum blkif_state {
62 BLKIF_STATE_DISCONNECTED,
63 BLKIF_STATE_CONNECTED,
64 BLKIF_STATE_SUSPENDED,
65 };
66
67 struct blk_shadow {
68 struct blkif_request req;
69 struct request *request;
70 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
71 };
72
73 static DEFINE_MUTEX(blkfront_mutex);
74 static const struct block_device_operations xlvbd_block_fops;
75
76 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
77
78 /*
79 * We have one of these per vbd, whether ide, scsi or 'other'. They
80 * hang in private_data off the gendisk structure. We may end up
81 * putting all kinds of interesting stuff here :-)
82 */
83 struct blkfront_info
84 {
85 spinlock_t io_lock;
86 struct mutex mutex;
87 struct xenbus_device *xbdev;
88 struct gendisk *gd;
89 int vdevice;
90 blkif_vdev_t handle;
91 enum blkif_state connected;
92 int ring_ref;
93 struct blkif_front_ring ring;
94 struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
95 unsigned int evtchn, irq;
96 struct request_queue *rq;
97 struct work_struct work;
98 struct gnttab_free_callback callback;
99 struct blk_shadow shadow[BLK_RING_SIZE];
100 unsigned long shadow_free;
101 unsigned int feature_flush;
102 unsigned int flush_op;
103 unsigned int feature_discard:1;
104 unsigned int feature_secdiscard:1;
105 unsigned int discard_granularity;
106 unsigned int discard_alignment;
107 int is_ready;
108 };
109
110 static unsigned int nr_minors;
111 static unsigned long *minors;
112 static DEFINE_SPINLOCK(minor_lock);
113
114 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
115 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
116 #define GRANT_INVALID_REF 0
117
118 #define PARTS_PER_DISK 16
119 #define PARTS_PER_EXT_DISK 256
120
121 #define BLKIF_MAJOR(dev) ((dev)>>8)
122 #define BLKIF_MINOR(dev) ((dev) & 0xff)
123
124 #define EXT_SHIFT 28
125 #define EXTENDED (1<<EXT_SHIFT)
126 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
127 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
128 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
129 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
130 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
131 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
132
133 #define DEV_NAME "xvd" /* name in /dev */
134
get_id_from_freelist(struct blkfront_info * info)135 static int get_id_from_freelist(struct blkfront_info *info)
136 {
137 unsigned long free = info->shadow_free;
138 BUG_ON(free >= BLK_RING_SIZE);
139 info->shadow_free = info->shadow[free].req.u.rw.id;
140 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
141 return free;
142 }
143
add_id_to_freelist(struct blkfront_info * info,unsigned long id)144 static void add_id_to_freelist(struct blkfront_info *info,
145 unsigned long id)
146 {
147 info->shadow[id].req.u.rw.id = info->shadow_free;
148 info->shadow[id].request = NULL;
149 info->shadow_free = id;
150 }
151
xlbd_reserve_minors(unsigned int minor,unsigned int nr)152 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
153 {
154 unsigned int end = minor + nr;
155 int rc;
156
157 if (end > nr_minors) {
158 unsigned long *bitmap, *old;
159
160 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
161 GFP_KERNEL);
162 if (bitmap == NULL)
163 return -ENOMEM;
164
165 spin_lock(&minor_lock);
166 if (end > nr_minors) {
167 old = minors;
168 memcpy(bitmap, minors,
169 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
170 minors = bitmap;
171 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
172 } else
173 old = bitmap;
174 spin_unlock(&minor_lock);
175 kfree(old);
176 }
177
178 spin_lock(&minor_lock);
179 if (find_next_bit(minors, end, minor) >= end) {
180 bitmap_set(minors, minor, nr);
181 rc = 0;
182 } else
183 rc = -EBUSY;
184 spin_unlock(&minor_lock);
185
186 return rc;
187 }
188
xlbd_release_minors(unsigned int minor,unsigned int nr)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 bitmap_clear(minors, minor, nr);
196 spin_unlock(&minor_lock);
197 }
198
blkif_restart_queue_callback(void * arg)199 static void blkif_restart_queue_callback(void *arg)
200 {
201 struct blkfront_info *info = (struct blkfront_info *)arg;
202 schedule_work(&info->work);
203 }
204
blkif_getgeo(struct block_device * bd,struct hd_geometry * hg)205 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
206 {
207 /* We don't have real geometry info, but let's at least return
208 values consistent with the size of the device */
209 sector_t nsect = get_capacity(bd->bd_disk);
210 sector_t cylinders = nsect;
211
212 hg->heads = 0xff;
213 hg->sectors = 0x3f;
214 sector_div(cylinders, hg->heads * hg->sectors);
215 hg->cylinders = cylinders;
216 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
217 hg->cylinders = 0xffff;
218 return 0;
219 }
220
blkif_ioctl(struct block_device * bdev,fmode_t mode,unsigned command,unsigned long argument)221 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
222 unsigned command, unsigned long argument)
223 {
224 struct blkfront_info *info = bdev->bd_disk->private_data;
225 int i;
226
227 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
228 command, (long)argument);
229
230 switch (command) {
231 case CDROMMULTISESSION:
232 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
233 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
234 if (put_user(0, (char __user *)(argument + i)))
235 return -EFAULT;
236 return 0;
237
238 case CDROM_GET_CAPABILITY: {
239 struct gendisk *gd = info->gd;
240 if (gd->flags & GENHD_FL_CD)
241 return 0;
242 return -EINVAL;
243 }
244
245 default:
246 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
247 command);*/
248 return -EINVAL; /* same return as native Linux */
249 }
250
251 return 0;
252 }
253
254 /*
255 * Generate a Xen blkfront IO request from a blk layer request. Reads
256 * and writes are handled as expected.
257 *
258 * @req: a request struct
259 */
blkif_queue_request(struct request * req)260 static int blkif_queue_request(struct request *req)
261 {
262 struct blkfront_info *info = req->rq_disk->private_data;
263 unsigned long buffer_mfn;
264 struct blkif_request *ring_req;
265 unsigned long id;
266 unsigned int fsect, lsect;
267 int i, ref;
268 grant_ref_t gref_head;
269 struct scatterlist *sg;
270
271 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
272 return 1;
273
274 if (gnttab_alloc_grant_references(
275 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
276 gnttab_request_free_callback(
277 &info->callback,
278 blkif_restart_queue_callback,
279 info,
280 BLKIF_MAX_SEGMENTS_PER_REQUEST);
281 return 1;
282 }
283
284 /* Fill out a communications ring structure. */
285 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
286 id = get_id_from_freelist(info);
287 info->shadow[id].request = req;
288
289 ring_req->u.rw.id = id;
290 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
291 ring_req->u.rw.handle = info->handle;
292
293 ring_req->operation = rq_data_dir(req) ?
294 BLKIF_OP_WRITE : BLKIF_OP_READ;
295
296 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
297 /*
298 * Ideally we can do an unordered flush-to-disk. In case the
299 * backend onlysupports barriers, use that. A barrier request
300 * a superset of FUA, so we can implement it the same
301 * way. (It's also a FLUSH+FUA, since it is
302 * guaranteed ordered WRT previous writes.)
303 */
304 ring_req->operation = info->flush_op;
305 }
306
307 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
308 /* id, sector_number and handle are set above. */
309 ring_req->operation = BLKIF_OP_DISCARD;
310 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
311 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
312 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
313 else
314 ring_req->u.discard.flag = 0;
315 } else {
316 ring_req->u.rw.nr_segments = blk_rq_map_sg(req->q, req,
317 info->sg);
318 BUG_ON(ring_req->u.rw.nr_segments >
319 BLKIF_MAX_SEGMENTS_PER_REQUEST);
320
321 for_each_sg(info->sg, sg, ring_req->u.rw.nr_segments, i) {
322 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
323 fsect = sg->offset >> 9;
324 lsect = fsect + (sg->length >> 9) - 1;
325 /* install a grant reference. */
326 ref = gnttab_claim_grant_reference(&gref_head);
327 BUG_ON(ref == -ENOSPC);
328
329 gnttab_grant_foreign_access_ref(
330 ref,
331 info->xbdev->otherend_id,
332 buffer_mfn,
333 rq_data_dir(req));
334
335 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
336 ring_req->u.rw.seg[i] =
337 (struct blkif_request_segment) {
338 .gref = ref,
339 .first_sect = fsect,
340 .last_sect = lsect };
341 }
342 }
343
344 info->ring.req_prod_pvt++;
345
346 /* Keep a private copy so we can reissue requests when recovering. */
347 info->shadow[id].req = *ring_req;
348
349 gnttab_free_grant_references(gref_head);
350
351 return 0;
352 }
353
354
flush_requests(struct blkfront_info * info)355 static inline void flush_requests(struct blkfront_info *info)
356 {
357 int notify;
358
359 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
360
361 if (notify)
362 notify_remote_via_irq(info->irq);
363 }
364
365 /*
366 * do_blkif_request
367 * read a block; request is in a request queue
368 */
do_blkif_request(struct request_queue * rq)369 static void do_blkif_request(struct request_queue *rq)
370 {
371 struct blkfront_info *info = NULL;
372 struct request *req;
373 int queued;
374
375 pr_debug("Entered do_blkif_request\n");
376
377 queued = 0;
378
379 while ((req = blk_peek_request(rq)) != NULL) {
380 info = req->rq_disk->private_data;
381
382 if (RING_FULL(&info->ring))
383 goto wait;
384
385 blk_start_request(req);
386
387 if ((req->cmd_type != REQ_TYPE_FS) ||
388 ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) &&
389 !info->flush_op)) {
390 __blk_end_request_all(req, -EIO);
391 continue;
392 }
393
394 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
395 "(%u/%u) buffer:%p [%s]\n",
396 req, req->cmd, (unsigned long)blk_rq_pos(req),
397 blk_rq_cur_sectors(req), blk_rq_sectors(req),
398 req->buffer, rq_data_dir(req) ? "write" : "read");
399
400 if (blkif_queue_request(req)) {
401 blk_requeue_request(rq, req);
402 wait:
403 /* Avoid pointless unplugs. */
404 blk_stop_queue(rq);
405 break;
406 }
407
408 queued++;
409 }
410
411 if (queued != 0)
412 flush_requests(info);
413 }
414
xlvbd_init_blk_queue(struct gendisk * gd,u16 sector_size)415 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
416 {
417 struct request_queue *rq;
418 struct blkfront_info *info = gd->private_data;
419
420 rq = blk_init_queue(do_blkif_request, &info->io_lock);
421 if (rq == NULL)
422 return -1;
423
424 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
425
426 if (info->feature_discard) {
427 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
428 blk_queue_max_discard_sectors(rq, get_capacity(gd));
429 rq->limits.discard_granularity = info->discard_granularity;
430 rq->limits.discard_alignment = info->discard_alignment;
431 if (info->feature_secdiscard)
432 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
433 }
434
435 /* Hard sector size and max sectors impersonate the equiv. hardware. */
436 blk_queue_logical_block_size(rq, sector_size);
437 blk_queue_max_hw_sectors(rq, 512);
438
439 /* Each segment in a request is up to an aligned page in size. */
440 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
441 blk_queue_max_segment_size(rq, PAGE_SIZE);
442
443 /* Ensure a merged request will fit in a single I/O ring slot. */
444 blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
445
446 /* Make sure buffer addresses are sector-aligned. */
447 blk_queue_dma_alignment(rq, 511);
448
449 /* Make sure we don't use bounce buffers. */
450 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
451
452 gd->queue = rq;
453
454 return 0;
455 }
456
457
xlvbd_flush(struct blkfront_info * info)458 static void xlvbd_flush(struct blkfront_info *info)
459 {
460 blk_queue_flush(info->rq, info->feature_flush);
461 printk(KERN_INFO "blkfront: %s: %s: %s\n",
462 info->gd->disk_name,
463 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
464 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
465 "flush diskcache" : "barrier or flush"),
466 info->feature_flush ? "enabled" : "disabled");
467 }
468
xen_translate_vdev(int vdevice,int * minor,unsigned int * offset)469 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
470 {
471 int major;
472 major = BLKIF_MAJOR(vdevice);
473 *minor = BLKIF_MINOR(vdevice);
474 switch (major) {
475 case XEN_IDE0_MAJOR:
476 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
477 *minor = ((*minor / 64) * PARTS_PER_DISK) +
478 EMULATED_HD_DISK_MINOR_OFFSET;
479 break;
480 case XEN_IDE1_MAJOR:
481 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
482 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
483 EMULATED_HD_DISK_MINOR_OFFSET;
484 break;
485 case XEN_SCSI_DISK0_MAJOR:
486 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
487 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
488 break;
489 case XEN_SCSI_DISK1_MAJOR:
490 case XEN_SCSI_DISK2_MAJOR:
491 case XEN_SCSI_DISK3_MAJOR:
492 case XEN_SCSI_DISK4_MAJOR:
493 case XEN_SCSI_DISK5_MAJOR:
494 case XEN_SCSI_DISK6_MAJOR:
495 case XEN_SCSI_DISK7_MAJOR:
496 *offset = (*minor / PARTS_PER_DISK) +
497 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
498 EMULATED_SD_DISK_NAME_OFFSET;
499 *minor = *minor +
500 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
501 EMULATED_SD_DISK_MINOR_OFFSET;
502 break;
503 case XEN_SCSI_DISK8_MAJOR:
504 case XEN_SCSI_DISK9_MAJOR:
505 case XEN_SCSI_DISK10_MAJOR:
506 case XEN_SCSI_DISK11_MAJOR:
507 case XEN_SCSI_DISK12_MAJOR:
508 case XEN_SCSI_DISK13_MAJOR:
509 case XEN_SCSI_DISK14_MAJOR:
510 case XEN_SCSI_DISK15_MAJOR:
511 *offset = (*minor / PARTS_PER_DISK) +
512 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
513 EMULATED_SD_DISK_NAME_OFFSET;
514 *minor = *minor +
515 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
516 EMULATED_SD_DISK_MINOR_OFFSET;
517 break;
518 case XENVBD_MAJOR:
519 *offset = *minor / PARTS_PER_DISK;
520 break;
521 default:
522 printk(KERN_WARNING "blkfront: your disk configuration is "
523 "incorrect, please use an xvd device instead\n");
524 return -ENODEV;
525 }
526 return 0;
527 }
528
xlvbd_alloc_gendisk(blkif_sector_t capacity,struct blkfront_info * info,u16 vdisk_info,u16 sector_size)529 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
530 struct blkfront_info *info,
531 u16 vdisk_info, u16 sector_size)
532 {
533 struct gendisk *gd;
534 int nr_minors = 1;
535 int err;
536 unsigned int offset;
537 int minor;
538 int nr_parts;
539
540 BUG_ON(info->gd != NULL);
541 BUG_ON(info->rq != NULL);
542
543 if ((info->vdevice>>EXT_SHIFT) > 1) {
544 /* this is above the extended range; something is wrong */
545 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
546 return -ENODEV;
547 }
548
549 if (!VDEV_IS_EXTENDED(info->vdevice)) {
550 err = xen_translate_vdev(info->vdevice, &minor, &offset);
551 if (err)
552 return err;
553 nr_parts = PARTS_PER_DISK;
554 } else {
555 minor = BLKIF_MINOR_EXT(info->vdevice);
556 nr_parts = PARTS_PER_EXT_DISK;
557 offset = minor / nr_parts;
558 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
559 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
560 "emulated IDE disks,\n\t choose an xvd device name"
561 "from xvde on\n", info->vdevice);
562 }
563 err = -ENODEV;
564
565 if ((minor % nr_parts) == 0)
566 nr_minors = nr_parts;
567
568 err = xlbd_reserve_minors(minor, nr_minors);
569 if (err)
570 goto out;
571 err = -ENODEV;
572
573 gd = alloc_disk(nr_minors);
574 if (gd == NULL)
575 goto release;
576
577 if (nr_minors > 1) {
578 if (offset < 26)
579 sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
580 else
581 sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
582 'a' + ((offset / 26)-1), 'a' + (offset % 26));
583 } else {
584 if (offset < 26)
585 sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
586 'a' + offset,
587 minor & (nr_parts - 1));
588 else
589 sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
590 'a' + ((offset / 26) - 1),
591 'a' + (offset % 26),
592 minor & (nr_parts - 1));
593 }
594
595 gd->major = XENVBD_MAJOR;
596 gd->first_minor = minor;
597 gd->fops = &xlvbd_block_fops;
598 gd->private_data = info;
599 gd->driverfs_dev = &(info->xbdev->dev);
600 set_capacity(gd, capacity);
601
602 if (xlvbd_init_blk_queue(gd, sector_size)) {
603 del_gendisk(gd);
604 goto release;
605 }
606
607 info->rq = gd->queue;
608 info->gd = gd;
609
610 xlvbd_flush(info);
611
612 if (vdisk_info & VDISK_READONLY)
613 set_disk_ro(gd, 1);
614
615 if (vdisk_info & VDISK_REMOVABLE)
616 gd->flags |= GENHD_FL_REMOVABLE;
617
618 if (vdisk_info & VDISK_CDROM)
619 gd->flags |= GENHD_FL_CD;
620
621 return 0;
622
623 release:
624 xlbd_release_minors(minor, nr_minors);
625 out:
626 return err;
627 }
628
xlvbd_release_gendisk(struct blkfront_info * info)629 static void xlvbd_release_gendisk(struct blkfront_info *info)
630 {
631 unsigned int minor, nr_minors;
632 unsigned long flags;
633
634 if (info->rq == NULL)
635 return;
636
637 spin_lock_irqsave(&info->io_lock, flags);
638
639 /* No more blkif_request(). */
640 blk_stop_queue(info->rq);
641
642 /* No more gnttab callback work. */
643 gnttab_cancel_free_callback(&info->callback);
644 spin_unlock_irqrestore(&info->io_lock, flags);
645
646 /* Flush gnttab callback work. Must be done with no locks held. */
647 flush_work_sync(&info->work);
648
649 del_gendisk(info->gd);
650
651 minor = info->gd->first_minor;
652 nr_minors = info->gd->minors;
653 xlbd_release_minors(minor, nr_minors);
654
655 blk_cleanup_queue(info->rq);
656 info->rq = NULL;
657
658 put_disk(info->gd);
659 info->gd = NULL;
660 }
661
kick_pending_request_queues(struct blkfront_info * info)662 static void kick_pending_request_queues(struct blkfront_info *info)
663 {
664 if (!RING_FULL(&info->ring)) {
665 /* Re-enable calldowns. */
666 blk_start_queue(info->rq);
667 /* Kick things off immediately. */
668 do_blkif_request(info->rq);
669 }
670 }
671
blkif_restart_queue(struct work_struct * work)672 static void blkif_restart_queue(struct work_struct *work)
673 {
674 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
675
676 spin_lock_irq(&info->io_lock);
677 if (info->connected == BLKIF_STATE_CONNECTED)
678 kick_pending_request_queues(info);
679 spin_unlock_irq(&info->io_lock);
680 }
681
blkif_free(struct blkfront_info * info,int suspend)682 static void blkif_free(struct blkfront_info *info, int suspend)
683 {
684 /* Prevent new requests being issued until we fix things up. */
685 spin_lock_irq(&info->io_lock);
686 info->connected = suspend ?
687 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
688 /* No more blkif_request(). */
689 if (info->rq)
690 blk_stop_queue(info->rq);
691 /* No more gnttab callback work. */
692 gnttab_cancel_free_callback(&info->callback);
693 spin_unlock_irq(&info->io_lock);
694
695 /* Flush gnttab callback work. Must be done with no locks held. */
696 flush_work_sync(&info->work);
697
698 /* Free resources associated with old device channel. */
699 if (info->ring_ref != GRANT_INVALID_REF) {
700 gnttab_end_foreign_access(info->ring_ref, 0,
701 (unsigned long)info->ring.sring);
702 info->ring_ref = GRANT_INVALID_REF;
703 info->ring.sring = NULL;
704 }
705 if (info->irq)
706 unbind_from_irqhandler(info->irq, info);
707 info->evtchn = info->irq = 0;
708
709 }
710
blkif_completion(struct blk_shadow * s)711 static void blkif_completion(struct blk_shadow *s)
712 {
713 int i;
714 /* Do not let BLKIF_OP_DISCARD as nr_segment is in the same place
715 * flag. */
716 for (i = 0; i < s->req.u.rw.nr_segments; i++)
717 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
718 }
719
blkif_interrupt(int irq,void * dev_id)720 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
721 {
722 struct request *req;
723 struct blkif_response *bret;
724 RING_IDX i, rp;
725 unsigned long flags;
726 struct blkfront_info *info = (struct blkfront_info *)dev_id;
727 int error;
728
729 spin_lock_irqsave(&info->io_lock, flags);
730
731 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
732 spin_unlock_irqrestore(&info->io_lock, flags);
733 return IRQ_HANDLED;
734 }
735
736 again:
737 rp = info->ring.sring->rsp_prod;
738 rmb(); /* Ensure we see queued responses up to 'rp'. */
739
740 for (i = info->ring.rsp_cons; i != rp; i++) {
741 unsigned long id;
742
743 bret = RING_GET_RESPONSE(&info->ring, i);
744 id = bret->id;
745 req = info->shadow[id].request;
746
747 if (bret->operation != BLKIF_OP_DISCARD)
748 blkif_completion(&info->shadow[id]);
749
750 add_id_to_freelist(info, id);
751
752 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
753 switch (bret->operation) {
754 case BLKIF_OP_DISCARD:
755 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
756 struct request_queue *rq = info->rq;
757 printk(KERN_WARNING "blkfront: %s: discard op failed\n",
758 info->gd->disk_name);
759 error = -EOPNOTSUPP;
760 info->feature_discard = 0;
761 info->feature_secdiscard = 0;
762 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
763 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
764 }
765 __blk_end_request_all(req, error);
766 break;
767 case BLKIF_OP_FLUSH_DISKCACHE:
768 case BLKIF_OP_WRITE_BARRIER:
769 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
770 printk(KERN_WARNING "blkfront: %s: write %s op failed\n",
771 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
772 "barrier" : "flush disk cache",
773 info->gd->disk_name);
774 error = -EOPNOTSUPP;
775 }
776 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
777 info->shadow[id].req.u.rw.nr_segments == 0)) {
778 printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
779 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
780 "barrier" : "flush disk cache",
781 info->gd->disk_name);
782 error = -EOPNOTSUPP;
783 }
784 if (unlikely(error)) {
785 if (error == -EOPNOTSUPP)
786 error = 0;
787 info->feature_flush = 0;
788 info->flush_op = 0;
789 xlvbd_flush(info);
790 }
791 /* fall through */
792 case BLKIF_OP_READ:
793 case BLKIF_OP_WRITE:
794 if (unlikely(bret->status != BLKIF_RSP_OKAY))
795 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
796 "request: %x\n", bret->status);
797
798 __blk_end_request_all(req, error);
799 break;
800 default:
801 BUG();
802 }
803 }
804
805 info->ring.rsp_cons = i;
806
807 if (i != info->ring.req_prod_pvt) {
808 int more_to_do;
809 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
810 if (more_to_do)
811 goto again;
812 } else
813 info->ring.sring->rsp_event = i + 1;
814
815 kick_pending_request_queues(info);
816
817 spin_unlock_irqrestore(&info->io_lock, flags);
818
819 return IRQ_HANDLED;
820 }
821
822
setup_blkring(struct xenbus_device * dev,struct blkfront_info * info)823 static int setup_blkring(struct xenbus_device *dev,
824 struct blkfront_info *info)
825 {
826 struct blkif_sring *sring;
827 int err;
828
829 info->ring_ref = GRANT_INVALID_REF;
830
831 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
832 if (!sring) {
833 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
834 return -ENOMEM;
835 }
836 SHARED_RING_INIT(sring);
837 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
838
839 sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
840
841 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
842 if (err < 0) {
843 free_page((unsigned long)sring);
844 info->ring.sring = NULL;
845 goto fail;
846 }
847 info->ring_ref = err;
848
849 err = xenbus_alloc_evtchn(dev, &info->evtchn);
850 if (err)
851 goto fail;
852
853 err = bind_evtchn_to_irqhandler(info->evtchn,
854 blkif_interrupt,
855 IRQF_SAMPLE_RANDOM, "blkif", info);
856 if (err <= 0) {
857 xenbus_dev_fatal(dev, err,
858 "bind_evtchn_to_irqhandler failed");
859 goto fail;
860 }
861 info->irq = err;
862
863 return 0;
864 fail:
865 blkif_free(info, 0);
866 return err;
867 }
868
869
870 /* Common code used when first setting up, and when resuming. */
talk_to_blkback(struct xenbus_device * dev,struct blkfront_info * info)871 static int talk_to_blkback(struct xenbus_device *dev,
872 struct blkfront_info *info)
873 {
874 const char *message = NULL;
875 struct xenbus_transaction xbt;
876 int err;
877
878 /* Create shared ring, alloc event channel. */
879 err = setup_blkring(dev, info);
880 if (err)
881 goto out;
882
883 again:
884 err = xenbus_transaction_start(&xbt);
885 if (err) {
886 xenbus_dev_fatal(dev, err, "starting transaction");
887 goto destroy_blkring;
888 }
889
890 err = xenbus_printf(xbt, dev->nodename,
891 "ring-ref", "%u", info->ring_ref);
892 if (err) {
893 message = "writing ring-ref";
894 goto abort_transaction;
895 }
896 err = xenbus_printf(xbt, dev->nodename,
897 "event-channel", "%u", info->evtchn);
898 if (err) {
899 message = "writing event-channel";
900 goto abort_transaction;
901 }
902 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
903 XEN_IO_PROTO_ABI_NATIVE);
904 if (err) {
905 message = "writing protocol";
906 goto abort_transaction;
907 }
908
909 err = xenbus_transaction_end(xbt, 0);
910 if (err) {
911 if (err == -EAGAIN)
912 goto again;
913 xenbus_dev_fatal(dev, err, "completing transaction");
914 goto destroy_blkring;
915 }
916
917 xenbus_switch_state(dev, XenbusStateInitialised);
918
919 return 0;
920
921 abort_transaction:
922 xenbus_transaction_end(xbt, 1);
923 if (message)
924 xenbus_dev_fatal(dev, err, "%s", message);
925 destroy_blkring:
926 blkif_free(info, 0);
927 out:
928 return err;
929 }
930
931 /**
932 * Entry point to this code when a new device is created. Allocate the basic
933 * structures and the ring buffer for communication with the backend, and
934 * inform the backend of the appropriate details for those. Switch to
935 * Initialised state.
936 */
blkfront_probe(struct xenbus_device * dev,const struct xenbus_device_id * id)937 static int blkfront_probe(struct xenbus_device *dev,
938 const struct xenbus_device_id *id)
939 {
940 int err, vdevice, i;
941 struct blkfront_info *info;
942
943 /* FIXME: Use dynamic device id if this is not set. */
944 err = xenbus_scanf(XBT_NIL, dev->nodename,
945 "virtual-device", "%i", &vdevice);
946 if (err != 1) {
947 /* go looking in the extended area instead */
948 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
949 "%i", &vdevice);
950 if (err != 1) {
951 xenbus_dev_fatal(dev, err, "reading virtual-device");
952 return err;
953 }
954 }
955
956 if (xen_hvm_domain()) {
957 char *type;
958 int len;
959 /* no unplug has been done: do not hook devices != xen vbds */
960 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
961 int major;
962
963 if (!VDEV_IS_EXTENDED(vdevice))
964 major = BLKIF_MAJOR(vdevice);
965 else
966 major = XENVBD_MAJOR;
967
968 if (major != XENVBD_MAJOR) {
969 printk(KERN_INFO
970 "%s: HVM does not support vbd %d as xen block device\n",
971 __FUNCTION__, vdevice);
972 return -ENODEV;
973 }
974 }
975 /* do not create a PV cdrom device if we are an HVM guest */
976 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
977 if (IS_ERR(type))
978 return -ENODEV;
979 if (strncmp(type, "cdrom", 5) == 0) {
980 kfree(type);
981 return -ENODEV;
982 }
983 kfree(type);
984 }
985 info = kzalloc(sizeof(*info), GFP_KERNEL);
986 if (!info) {
987 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
988 return -ENOMEM;
989 }
990
991 mutex_init(&info->mutex);
992 spin_lock_init(&info->io_lock);
993 info->xbdev = dev;
994 info->vdevice = vdevice;
995 info->connected = BLKIF_STATE_DISCONNECTED;
996 INIT_WORK(&info->work, blkif_restart_queue);
997
998 for (i = 0; i < BLK_RING_SIZE; i++)
999 info->shadow[i].req.u.rw.id = i+1;
1000 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1001
1002 /* Front end dir is a number, which is used as the id. */
1003 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1004 dev_set_drvdata(&dev->dev, info);
1005
1006 err = talk_to_blkback(dev, info);
1007 if (err) {
1008 kfree(info);
1009 dev_set_drvdata(&dev->dev, NULL);
1010 return err;
1011 }
1012
1013 return 0;
1014 }
1015
1016
blkif_recover(struct blkfront_info * info)1017 static int blkif_recover(struct blkfront_info *info)
1018 {
1019 int i;
1020 struct blkif_request *req;
1021 struct blk_shadow *copy;
1022 int j;
1023
1024 /* Stage 1: Make a safe copy of the shadow state. */
1025 copy = kmalloc(sizeof(info->shadow),
1026 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1027 if (!copy)
1028 return -ENOMEM;
1029 memcpy(copy, info->shadow, sizeof(info->shadow));
1030
1031 /* Stage 2: Set up free list. */
1032 memset(&info->shadow, 0, sizeof(info->shadow));
1033 for (i = 0; i < BLK_RING_SIZE; i++)
1034 info->shadow[i].req.u.rw.id = i+1;
1035 info->shadow_free = info->ring.req_prod_pvt;
1036 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1037
1038 /* Stage 3: Find pending requests and requeue them. */
1039 for (i = 0; i < BLK_RING_SIZE; i++) {
1040 /* Not in use? */
1041 if (!copy[i].request)
1042 continue;
1043
1044 /* Grab a request slot and copy shadow state into it. */
1045 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
1046 *req = copy[i].req;
1047
1048 /* We get a new request id, and must reset the shadow state. */
1049 req->u.rw.id = get_id_from_freelist(info);
1050 memcpy(&info->shadow[req->u.rw.id], ©[i], sizeof(copy[i]));
1051
1052 if (req->operation != BLKIF_OP_DISCARD) {
1053 /* Rewrite any grant references invalidated by susp/resume. */
1054 for (j = 0; j < req->u.rw.nr_segments; j++)
1055 gnttab_grant_foreign_access_ref(
1056 req->u.rw.seg[j].gref,
1057 info->xbdev->otherend_id,
1058 pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]),
1059 rq_data_dir(info->shadow[req->u.rw.id].request));
1060 }
1061 info->shadow[req->u.rw.id].req = *req;
1062
1063 info->ring.req_prod_pvt++;
1064 }
1065
1066 kfree(copy);
1067
1068 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1069
1070 spin_lock_irq(&info->io_lock);
1071
1072 /* Now safe for us to use the shared ring */
1073 info->connected = BLKIF_STATE_CONNECTED;
1074
1075 /* Send off requeued requests */
1076 flush_requests(info);
1077
1078 /* Kick any other new requests queued since we resumed */
1079 kick_pending_request_queues(info);
1080
1081 spin_unlock_irq(&info->io_lock);
1082
1083 return 0;
1084 }
1085
1086 /**
1087 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1088 * driver restart. We tear down our blkif structure and recreate it, but
1089 * leave the device-layer structures intact so that this is transparent to the
1090 * rest of the kernel.
1091 */
blkfront_resume(struct xenbus_device * dev)1092 static int blkfront_resume(struct xenbus_device *dev)
1093 {
1094 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1095 int err;
1096
1097 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1098
1099 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1100
1101 err = talk_to_blkback(dev, info);
1102 if (info->connected == BLKIF_STATE_SUSPENDED && !err)
1103 err = blkif_recover(info);
1104
1105 return err;
1106 }
1107
1108 static void
blkfront_closing(struct blkfront_info * info)1109 blkfront_closing(struct blkfront_info *info)
1110 {
1111 struct xenbus_device *xbdev = info->xbdev;
1112 struct block_device *bdev = NULL;
1113
1114 mutex_lock(&info->mutex);
1115
1116 if (xbdev->state == XenbusStateClosing) {
1117 mutex_unlock(&info->mutex);
1118 return;
1119 }
1120
1121 if (info->gd)
1122 bdev = bdget_disk(info->gd, 0);
1123
1124 mutex_unlock(&info->mutex);
1125
1126 if (!bdev) {
1127 xenbus_frontend_closed(xbdev);
1128 return;
1129 }
1130
1131 mutex_lock(&bdev->bd_mutex);
1132
1133 if (bdev->bd_openers) {
1134 xenbus_dev_error(xbdev, -EBUSY,
1135 "Device in use; refusing to close");
1136 xenbus_switch_state(xbdev, XenbusStateClosing);
1137 } else {
1138 xlvbd_release_gendisk(info);
1139 xenbus_frontend_closed(xbdev);
1140 }
1141
1142 mutex_unlock(&bdev->bd_mutex);
1143 bdput(bdev);
1144 }
1145
blkfront_setup_discard(struct blkfront_info * info)1146 static void blkfront_setup_discard(struct blkfront_info *info)
1147 {
1148 int err;
1149 char *type;
1150 unsigned int discard_granularity;
1151 unsigned int discard_alignment;
1152 unsigned int discard_secure;
1153
1154 type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
1155 if (IS_ERR(type))
1156 return;
1157
1158 info->feature_secdiscard = 0;
1159 if (strncmp(type, "phy", 3) == 0) {
1160 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1161 "discard-granularity", "%u", &discard_granularity,
1162 "discard-alignment", "%u", &discard_alignment,
1163 NULL);
1164 if (!err) {
1165 info->feature_discard = 1;
1166 info->discard_granularity = discard_granularity;
1167 info->discard_alignment = discard_alignment;
1168 }
1169 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1170 "discard-secure", "%d", &discard_secure,
1171 NULL);
1172 if (!err)
1173 info->feature_secdiscard = discard_secure;
1174
1175 } else if (strncmp(type, "file", 4) == 0)
1176 info->feature_discard = 1;
1177
1178 kfree(type);
1179 }
1180
1181 /*
1182 * Invoked when the backend is finally 'ready' (and has told produced
1183 * the details about the physical device - #sectors, size, etc).
1184 */
blkfront_connect(struct blkfront_info * info)1185 static void blkfront_connect(struct blkfront_info *info)
1186 {
1187 unsigned long long sectors;
1188 unsigned long sector_size;
1189 unsigned int binfo;
1190 int err;
1191 int barrier, flush, discard;
1192
1193 switch (info->connected) {
1194 case BLKIF_STATE_CONNECTED:
1195 /*
1196 * Potentially, the back-end may be signalling
1197 * a capacity change; update the capacity.
1198 */
1199 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1200 "sectors", "%Lu", §ors);
1201 if (XENBUS_EXIST_ERR(err))
1202 return;
1203 printk(KERN_INFO "Setting capacity to %Lu\n",
1204 sectors);
1205 set_capacity(info->gd, sectors);
1206 revalidate_disk(info->gd);
1207
1208 /* fall through */
1209 case BLKIF_STATE_SUSPENDED:
1210 return;
1211
1212 default:
1213 break;
1214 }
1215
1216 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1217 __func__, info->xbdev->otherend);
1218
1219 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1220 "sectors", "%llu", §ors,
1221 "info", "%u", &binfo,
1222 "sector-size", "%lu", §or_size,
1223 NULL);
1224 if (err) {
1225 xenbus_dev_fatal(info->xbdev, err,
1226 "reading backend fields at %s",
1227 info->xbdev->otherend);
1228 return;
1229 }
1230
1231 info->feature_flush = 0;
1232 info->flush_op = 0;
1233
1234 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1235 "feature-barrier", "%d", &barrier,
1236 NULL);
1237
1238 /*
1239 * If there's no "feature-barrier" defined, then it means
1240 * we're dealing with a very old backend which writes
1241 * synchronously; nothing to do.
1242 *
1243 * If there are barriers, then we use flush.
1244 */
1245 if (!err && barrier) {
1246 info->feature_flush = REQ_FLUSH | REQ_FUA;
1247 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1248 }
1249 /*
1250 * And if there is "feature-flush-cache" use that above
1251 * barriers.
1252 */
1253 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1254 "feature-flush-cache", "%d", &flush,
1255 NULL);
1256
1257 if (!err && flush) {
1258 info->feature_flush = REQ_FLUSH;
1259 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1260 }
1261
1262 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1263 "feature-discard", "%d", &discard,
1264 NULL);
1265
1266 if (!err && discard)
1267 blkfront_setup_discard(info);
1268
1269 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1270 if (err) {
1271 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1272 info->xbdev->otherend);
1273 return;
1274 }
1275
1276 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1277
1278 /* Kick pending requests. */
1279 spin_lock_irq(&info->io_lock);
1280 info->connected = BLKIF_STATE_CONNECTED;
1281 kick_pending_request_queues(info);
1282 spin_unlock_irq(&info->io_lock);
1283
1284 add_disk(info->gd);
1285
1286 info->is_ready = 1;
1287 }
1288
1289 /**
1290 * Callback received when the backend's state changes.
1291 */
blkback_changed(struct xenbus_device * dev,enum xenbus_state backend_state)1292 static void blkback_changed(struct xenbus_device *dev,
1293 enum xenbus_state backend_state)
1294 {
1295 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1296
1297 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1298
1299 switch (backend_state) {
1300 case XenbusStateInitialising:
1301 case XenbusStateInitWait:
1302 case XenbusStateInitialised:
1303 case XenbusStateReconfiguring:
1304 case XenbusStateReconfigured:
1305 case XenbusStateUnknown:
1306 break;
1307
1308 case XenbusStateConnected:
1309 blkfront_connect(info);
1310 break;
1311
1312 case XenbusStateClosed:
1313 if (dev->state == XenbusStateClosed)
1314 break;
1315 /* Missed the backend's Closing state -- fallthrough */
1316 case XenbusStateClosing:
1317 blkfront_closing(info);
1318 break;
1319 }
1320 }
1321
blkfront_remove(struct xenbus_device * xbdev)1322 static int blkfront_remove(struct xenbus_device *xbdev)
1323 {
1324 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1325 struct block_device *bdev = NULL;
1326 struct gendisk *disk;
1327
1328 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1329
1330 blkif_free(info, 0);
1331
1332 mutex_lock(&info->mutex);
1333
1334 disk = info->gd;
1335 if (disk)
1336 bdev = bdget_disk(disk, 0);
1337
1338 info->xbdev = NULL;
1339 mutex_unlock(&info->mutex);
1340
1341 if (!bdev) {
1342 kfree(info);
1343 return 0;
1344 }
1345
1346 /*
1347 * The xbdev was removed before we reached the Closed
1348 * state. See if it's safe to remove the disk. If the bdev
1349 * isn't closed yet, we let release take care of it.
1350 */
1351
1352 mutex_lock(&bdev->bd_mutex);
1353 info = disk->private_data;
1354
1355 dev_warn(disk_to_dev(disk),
1356 "%s was hot-unplugged, %d stale handles\n",
1357 xbdev->nodename, bdev->bd_openers);
1358
1359 if (info && !bdev->bd_openers) {
1360 xlvbd_release_gendisk(info);
1361 disk->private_data = NULL;
1362 kfree(info);
1363 }
1364
1365 mutex_unlock(&bdev->bd_mutex);
1366 bdput(bdev);
1367
1368 return 0;
1369 }
1370
blkfront_is_ready(struct xenbus_device * dev)1371 static int blkfront_is_ready(struct xenbus_device *dev)
1372 {
1373 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1374
1375 return info->is_ready && info->xbdev;
1376 }
1377
blkif_open(struct block_device * bdev,fmode_t mode)1378 static int blkif_open(struct block_device *bdev, fmode_t mode)
1379 {
1380 struct gendisk *disk = bdev->bd_disk;
1381 struct blkfront_info *info;
1382 int err = 0;
1383
1384 mutex_lock(&blkfront_mutex);
1385
1386 info = disk->private_data;
1387 if (!info) {
1388 /* xbdev gone */
1389 err = -ERESTARTSYS;
1390 goto out;
1391 }
1392
1393 mutex_lock(&info->mutex);
1394
1395 if (!info->gd)
1396 /* xbdev is closed */
1397 err = -ERESTARTSYS;
1398
1399 mutex_unlock(&info->mutex);
1400
1401 out:
1402 mutex_unlock(&blkfront_mutex);
1403 return err;
1404 }
1405
blkif_release(struct gendisk * disk,fmode_t mode)1406 static int blkif_release(struct gendisk *disk, fmode_t mode)
1407 {
1408 struct blkfront_info *info = disk->private_data;
1409 struct block_device *bdev;
1410 struct xenbus_device *xbdev;
1411
1412 mutex_lock(&blkfront_mutex);
1413
1414 bdev = bdget_disk(disk, 0);
1415
1416 if (bdev->bd_openers)
1417 goto out;
1418
1419 /*
1420 * Check if we have been instructed to close. We will have
1421 * deferred this request, because the bdev was still open.
1422 */
1423
1424 mutex_lock(&info->mutex);
1425 xbdev = info->xbdev;
1426
1427 if (xbdev && xbdev->state == XenbusStateClosing) {
1428 /* pending switch to state closed */
1429 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1430 xlvbd_release_gendisk(info);
1431 xenbus_frontend_closed(info->xbdev);
1432 }
1433
1434 mutex_unlock(&info->mutex);
1435
1436 if (!xbdev) {
1437 /* sudden device removal */
1438 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1439 xlvbd_release_gendisk(info);
1440 disk->private_data = NULL;
1441 kfree(info);
1442 }
1443
1444 out:
1445 bdput(bdev);
1446 mutex_unlock(&blkfront_mutex);
1447 return 0;
1448 }
1449
1450 static const struct block_device_operations xlvbd_block_fops =
1451 {
1452 .owner = THIS_MODULE,
1453 .open = blkif_open,
1454 .release = blkif_release,
1455 .getgeo = blkif_getgeo,
1456 .ioctl = blkif_ioctl,
1457 };
1458
1459
1460 static const struct xenbus_device_id blkfront_ids[] = {
1461 { "vbd" },
1462 { "" }
1463 };
1464
1465 static DEFINE_XENBUS_DRIVER(blkfront, ,
1466 .probe = blkfront_probe,
1467 .remove = blkfront_remove,
1468 .resume = blkfront_resume,
1469 .otherend_changed = blkback_changed,
1470 .is_ready = blkfront_is_ready,
1471 );
1472
xlblk_init(void)1473 static int __init xlblk_init(void)
1474 {
1475 int ret;
1476
1477 if (!xen_domain())
1478 return -ENODEV;
1479
1480 if (xen_hvm_domain() && !xen_platform_pci_unplug)
1481 return -ENODEV;
1482
1483 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1484 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1485 XENVBD_MAJOR, DEV_NAME);
1486 return -ENODEV;
1487 }
1488
1489 ret = xenbus_register_frontend(&blkfront_driver);
1490 if (ret) {
1491 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
1492 return ret;
1493 }
1494
1495 return 0;
1496 }
1497 module_init(xlblk_init);
1498
1499
xlblk_exit(void)1500 static void __exit xlblk_exit(void)
1501 {
1502 return xenbus_unregister_driver(&blkfront_driver);
1503 }
1504 module_exit(xlblk_exit);
1505
1506 MODULE_DESCRIPTION("Xen virtual block device frontend");
1507 MODULE_LICENSE("GPL");
1508 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1509 MODULE_ALIAS("xen:vbd");
1510 MODULE_ALIAS("xenblk");
1511