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Merge branch 'fixes-rc1' into omap-for-v4.3/fixes
[deliverable/linux.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/blk-mq.h>
41 #include <linux/hdreg.h>
42 #include <linux/cdrom.h>
43 #include <linux/module.h>
44 #include <linux/slab.h>
45 #include <linux/mutex.h>
46 #include <linux/scatterlist.h>
47 #include <linux/bitmap.h>
48 #include <linux/list.h>
49
50 #include <xen/xen.h>
51 #include <xen/xenbus.h>
52 #include <xen/grant_table.h>
53 #include <xen/events.h>
54 #include <xen/page.h>
55 #include <xen/platform_pci.h>
56
57 #include <xen/interface/grant_table.h>
58 #include <xen/interface/io/blkif.h>
59 #include <xen/interface/io/protocols.h>
60
61 #include <asm/xen/hypervisor.h>
62
63 enum blkif_state {
64 BLKIF_STATE_DISCONNECTED,
65 BLKIF_STATE_CONNECTED,
66 BLKIF_STATE_SUSPENDED,
67 };
68
69 struct grant {
70 grant_ref_t gref;
71 unsigned long pfn;
72 struct list_head node;
73 };
74
75 struct blk_shadow {
76 struct blkif_request req;
77 struct request *request;
78 struct grant **grants_used;
79 struct grant **indirect_grants;
80 struct scatterlist *sg;
81 };
82
83 struct split_bio {
84 struct bio *bio;
85 atomic_t pending;
86 };
87
88 static DEFINE_MUTEX(blkfront_mutex);
89 static const struct block_device_operations xlvbd_block_fops;
90
91 /*
92 * Maximum number of segments in indirect requests, the actual value used by
93 * the frontend driver is the minimum of this value and the value provided
94 * by the backend driver.
95 */
96
97 static unsigned int xen_blkif_max_segments = 32;
98 module_param_named(max, xen_blkif_max_segments, int, S_IRUGO);
99 MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)");
100
101 /*
102 * Maximum order of pages to be used for the shared ring between front and
103 * backend, 4KB page granularity is used.
104 */
105 static unsigned int xen_blkif_max_ring_order;
106 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO);
107 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
108
109 #define BLK_RING_SIZE(info) __CONST_RING_SIZE(blkif, PAGE_SIZE * (info)->nr_ring_pages)
110 #define BLK_MAX_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE * XENBUS_MAX_RING_PAGES)
111 /*
112 * ring-ref%i i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
113 * characters are enough. Define to 20 to keep consist with backend.
114 */
115 #define RINGREF_NAME_LEN (20)
116
117 /*
118 * We have one of these per vbd, whether ide, scsi or 'other'. They
119 * hang in private_data off the gendisk structure. We may end up
120 * putting all kinds of interesting stuff here :-)
121 */
122 struct blkfront_info
123 {
124 spinlock_t io_lock;
125 struct mutex mutex;
126 struct xenbus_device *xbdev;
127 struct gendisk *gd;
128 int vdevice;
129 blkif_vdev_t handle;
130 enum blkif_state connected;
131 int ring_ref[XENBUS_MAX_RING_PAGES];
132 unsigned int nr_ring_pages;
133 struct blkif_front_ring ring;
134 unsigned int evtchn, irq;
135 struct request_queue *rq;
136 struct work_struct work;
137 struct gnttab_free_callback callback;
138 struct blk_shadow shadow[BLK_MAX_RING_SIZE];
139 struct list_head grants;
140 struct list_head indirect_pages;
141 unsigned int persistent_gnts_c;
142 unsigned long shadow_free;
143 unsigned int feature_flush;
144 unsigned int feature_discard:1;
145 unsigned int feature_secdiscard:1;
146 unsigned int discard_granularity;
147 unsigned int discard_alignment;
148 unsigned int feature_persistent:1;
149 unsigned int max_indirect_segments;
150 int is_ready;
151 struct blk_mq_tag_set tag_set;
152 };
153
154 static unsigned int nr_minors;
155 static unsigned long *minors;
156 static DEFINE_SPINLOCK(minor_lock);
157
158 #define GRANT_INVALID_REF 0
159
160 #define PARTS_PER_DISK 16
161 #define PARTS_PER_EXT_DISK 256
162
163 #define BLKIF_MAJOR(dev) ((dev)>>8)
164 #define BLKIF_MINOR(dev) ((dev) & 0xff)
165
166 #define EXT_SHIFT 28
167 #define EXTENDED (1<<EXT_SHIFT)
168 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
169 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
170 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
171 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
172 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
173 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
174
175 #define DEV_NAME "xvd" /* name in /dev */
176
177 #define SEGS_PER_INDIRECT_FRAME \
178 (PAGE_SIZE/sizeof(struct blkif_request_segment))
179 #define INDIRECT_GREFS(_segs) \
180 ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
181
182 static int blkfront_setup_indirect(struct blkfront_info *info);
183 static int blkfront_gather_backend_features(struct blkfront_info *info);
184
185 static int get_id_from_freelist(struct blkfront_info *info)
186 {
187 unsigned long free = info->shadow_free;
188 BUG_ON(free >= BLK_RING_SIZE(info));
189 info->shadow_free = info->shadow[free].req.u.rw.id;
190 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
191 return free;
192 }
193
194 static int add_id_to_freelist(struct blkfront_info *info,
195 unsigned long id)
196 {
197 if (info->shadow[id].req.u.rw.id != id)
198 return -EINVAL;
199 if (info->shadow[id].request == NULL)
200 return -EINVAL;
201 info->shadow[id].req.u.rw.id = info->shadow_free;
202 info->shadow[id].request = NULL;
203 info->shadow_free = id;
204 return 0;
205 }
206
207 static int fill_grant_buffer(struct blkfront_info *info, int num)
208 {
209 struct page *granted_page;
210 struct grant *gnt_list_entry, *n;
211 int i = 0;
212
213 while(i < num) {
214 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
215 if (!gnt_list_entry)
216 goto out_of_memory;
217
218 if (info->feature_persistent) {
219 granted_page = alloc_page(GFP_NOIO);
220 if (!granted_page) {
221 kfree(gnt_list_entry);
222 goto out_of_memory;
223 }
224 gnt_list_entry->pfn = page_to_pfn(granted_page);
225 }
226
227 gnt_list_entry->gref = GRANT_INVALID_REF;
228 list_add(&gnt_list_entry->node, &info->grants);
229 i++;
230 }
231
232 return 0;
233
234 out_of_memory:
235 list_for_each_entry_safe(gnt_list_entry, n,
236 &info->grants, node) {
237 list_del(&gnt_list_entry->node);
238 if (info->feature_persistent)
239 __free_page(pfn_to_page(gnt_list_entry->pfn));
240 kfree(gnt_list_entry);
241 i--;
242 }
243 BUG_ON(i != 0);
244 return -ENOMEM;
245 }
246
247 static struct grant *get_grant(grant_ref_t *gref_head,
248 unsigned long pfn,
249 struct blkfront_info *info)
250 {
251 struct grant *gnt_list_entry;
252 unsigned long buffer_gfn;
253
254 BUG_ON(list_empty(&info->grants));
255 gnt_list_entry = list_first_entry(&info->grants, struct grant,
256 node);
257 list_del(&gnt_list_entry->node);
258
259 if (gnt_list_entry->gref != GRANT_INVALID_REF) {
260 info->persistent_gnts_c--;
261 return gnt_list_entry;
262 }
263
264 /* Assign a gref to this page */
265 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
266 BUG_ON(gnt_list_entry->gref == -ENOSPC);
267 if (!info->feature_persistent) {
268 BUG_ON(!pfn);
269 gnt_list_entry->pfn = pfn;
270 }
271 buffer_gfn = pfn_to_gfn(gnt_list_entry->pfn);
272 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
273 info->xbdev->otherend_id,
274 buffer_gfn, 0);
275 return gnt_list_entry;
276 }
277
278 static const char *op_name(int op)
279 {
280 static const char *const names[] = {
281 [BLKIF_OP_READ] = "read",
282 [BLKIF_OP_WRITE] = "write",
283 [BLKIF_OP_WRITE_BARRIER] = "barrier",
284 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
285 [BLKIF_OP_DISCARD] = "discard" };
286
287 if (op < 0 || op >= ARRAY_SIZE(names))
288 return "unknown";
289
290 if (!names[op])
291 return "reserved";
292
293 return names[op];
294 }
295 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
296 {
297 unsigned int end = minor + nr;
298 int rc;
299
300 if (end > nr_minors) {
301 unsigned long *bitmap, *old;
302
303 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
304 GFP_KERNEL);
305 if (bitmap == NULL)
306 return -ENOMEM;
307
308 spin_lock(&minor_lock);
309 if (end > nr_minors) {
310 old = minors;
311 memcpy(bitmap, minors,
312 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
313 minors = bitmap;
314 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
315 } else
316 old = bitmap;
317 spin_unlock(&minor_lock);
318 kfree(old);
319 }
320
321 spin_lock(&minor_lock);
322 if (find_next_bit(minors, end, minor) >= end) {
323 bitmap_set(minors, minor, nr);
324 rc = 0;
325 } else
326 rc = -EBUSY;
327 spin_unlock(&minor_lock);
328
329 return rc;
330 }
331
332 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
333 {
334 unsigned int end = minor + nr;
335
336 BUG_ON(end > nr_minors);
337 spin_lock(&minor_lock);
338 bitmap_clear(minors, minor, nr);
339 spin_unlock(&minor_lock);
340 }
341
342 static void blkif_restart_queue_callback(void *arg)
343 {
344 struct blkfront_info *info = (struct blkfront_info *)arg;
345 schedule_work(&info->work);
346 }
347
348 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
349 {
350 /* We don't have real geometry info, but let's at least return
351 values consistent with the size of the device */
352 sector_t nsect = get_capacity(bd->bd_disk);
353 sector_t cylinders = nsect;
354
355 hg->heads = 0xff;
356 hg->sectors = 0x3f;
357 sector_div(cylinders, hg->heads * hg->sectors);
358 hg->cylinders = cylinders;
359 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
360 hg->cylinders = 0xffff;
361 return 0;
362 }
363
364 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
365 unsigned command, unsigned long argument)
366 {
367 struct blkfront_info *info = bdev->bd_disk->private_data;
368 int i;
369
370 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
371 command, (long)argument);
372
373 switch (command) {
374 case CDROMMULTISESSION:
375 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
376 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
377 if (put_user(0, (char __user *)(argument + i)))
378 return -EFAULT;
379 return 0;
380
381 case CDROM_GET_CAPABILITY: {
382 struct gendisk *gd = info->gd;
383 if (gd->flags & GENHD_FL_CD)
384 return 0;
385 return -EINVAL;
386 }
387
388 default:
389 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
390 command);*/
391 return -EINVAL; /* same return as native Linux */
392 }
393
394 return 0;
395 }
396
397 /*
398 * Generate a Xen blkfront IO request from a blk layer request. Reads
399 * and writes are handled as expected.
400 *
401 * @req: a request struct
402 */
403 static int blkif_queue_request(struct request *req)
404 {
405 struct blkfront_info *info = req->rq_disk->private_data;
406 struct blkif_request *ring_req;
407 unsigned long id;
408 unsigned int fsect, lsect;
409 int i, ref, n;
410 struct blkif_request_segment *segments = NULL;
411
412 /*
413 * Used to store if we are able to queue the request by just using
414 * existing persistent grants, or if we have to get new grants,
415 * as there are not sufficiently many free.
416 */
417 bool new_persistent_gnts;
418 grant_ref_t gref_head;
419 struct grant *gnt_list_entry = NULL;
420 struct scatterlist *sg;
421 int nseg, max_grefs;
422
423 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
424 return 1;
425
426 max_grefs = req->nr_phys_segments;
427 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
428 /*
429 * If we are using indirect segments we need to account
430 * for the indirect grefs used in the request.
431 */
432 max_grefs += INDIRECT_GREFS(req->nr_phys_segments);
433
434 /* Check if we have enough grants to allocate a requests */
435 if (info->persistent_gnts_c < max_grefs) {
436 new_persistent_gnts = 1;
437 if (gnttab_alloc_grant_references(
438 max_grefs - info->persistent_gnts_c,
439 &gref_head) < 0) {
440 gnttab_request_free_callback(
441 &info->callback,
442 blkif_restart_queue_callback,
443 info,
444 max_grefs);
445 return 1;
446 }
447 } else
448 new_persistent_gnts = 0;
449
450 /* Fill out a communications ring structure. */
451 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
452 id = get_id_from_freelist(info);
453 info->shadow[id].request = req;
454
455 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
456 ring_req->operation = BLKIF_OP_DISCARD;
457 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
458 ring_req->u.discard.id = id;
459 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
460 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
461 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
462 else
463 ring_req->u.discard.flag = 0;
464 } else {
465 BUG_ON(info->max_indirect_segments == 0 &&
466 req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
467 BUG_ON(info->max_indirect_segments &&
468 req->nr_phys_segments > info->max_indirect_segments);
469 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
470 ring_req->u.rw.id = id;
471 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
472 /*
473 * The indirect operation can only be a BLKIF_OP_READ or
474 * BLKIF_OP_WRITE
475 */
476 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
477 ring_req->operation = BLKIF_OP_INDIRECT;
478 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
479 BLKIF_OP_WRITE : BLKIF_OP_READ;
480 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
481 ring_req->u.indirect.handle = info->handle;
482 ring_req->u.indirect.nr_segments = nseg;
483 } else {
484 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
485 ring_req->u.rw.handle = info->handle;
486 ring_req->operation = rq_data_dir(req) ?
487 BLKIF_OP_WRITE : BLKIF_OP_READ;
488 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
489 /*
490 * Ideally we can do an unordered flush-to-disk. In case the
491 * backend onlysupports barriers, use that. A barrier request
492 * a superset of FUA, so we can implement it the same
493 * way. (It's also a FLUSH+FUA, since it is
494 * guaranteed ordered WRT previous writes.)
495 */
496 switch (info->feature_flush &
497 ((REQ_FLUSH|REQ_FUA))) {
498 case REQ_FLUSH|REQ_FUA:
499 ring_req->operation =
500 BLKIF_OP_WRITE_BARRIER;
501 break;
502 case REQ_FLUSH:
503 ring_req->operation =
504 BLKIF_OP_FLUSH_DISKCACHE;
505 break;
506 default:
507 ring_req->operation = 0;
508 }
509 }
510 ring_req->u.rw.nr_segments = nseg;
511 }
512 for_each_sg(info->shadow[id].sg, sg, nseg, i) {
513 fsect = sg->offset >> 9;
514 lsect = fsect + (sg->length >> 9) - 1;
515
516 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
517 (i % SEGS_PER_INDIRECT_FRAME == 0)) {
518 unsigned long uninitialized_var(pfn);
519
520 if (segments)
521 kunmap_atomic(segments);
522
523 n = i / SEGS_PER_INDIRECT_FRAME;
524 if (!info->feature_persistent) {
525 struct page *indirect_page;
526
527 /* Fetch a pre-allocated page to use for indirect grefs */
528 BUG_ON(list_empty(&info->indirect_pages));
529 indirect_page = list_first_entry(&info->indirect_pages,
530 struct page, lru);
531 list_del(&indirect_page->lru);
532 pfn = page_to_pfn(indirect_page);
533 }
534 gnt_list_entry = get_grant(&gref_head, pfn, info);
535 info->shadow[id].indirect_grants[n] = gnt_list_entry;
536 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
537 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
538 }
539
540 gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
541 ref = gnt_list_entry->gref;
542
543 info->shadow[id].grants_used[i] = gnt_list_entry;
544
545 if (rq_data_dir(req) && info->feature_persistent) {
546 char *bvec_data;
547 void *shared_data;
548
549 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
550
551 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
552 bvec_data = kmap_atomic(sg_page(sg));
553
554 /*
555 * this does not wipe data stored outside the
556 * range sg->offset..sg->offset+sg->length.
557 * Therefore, blkback *could* see data from
558 * previous requests. This is OK as long as
559 * persistent grants are shared with just one
560 * domain. It may need refactoring if this
561 * changes
562 */
563 memcpy(shared_data + sg->offset,
564 bvec_data + sg->offset,
565 sg->length);
566
567 kunmap_atomic(bvec_data);
568 kunmap_atomic(shared_data);
569 }
570 if (ring_req->operation != BLKIF_OP_INDIRECT) {
571 ring_req->u.rw.seg[i] =
572 (struct blkif_request_segment) {
573 .gref = ref,
574 .first_sect = fsect,
575 .last_sect = lsect };
576 } else {
577 n = i % SEGS_PER_INDIRECT_FRAME;
578 segments[n] =
579 (struct blkif_request_segment) {
580 .gref = ref,
581 .first_sect = fsect,
582 .last_sect = lsect };
583 }
584 }
585 if (segments)
586 kunmap_atomic(segments);
587 }
588
589 info->ring.req_prod_pvt++;
590
591 /* Keep a private copy so we can reissue requests when recovering. */
592 info->shadow[id].req = *ring_req;
593
594 if (new_persistent_gnts)
595 gnttab_free_grant_references(gref_head);
596
597 return 0;
598 }
599
600
601 static inline void flush_requests(struct blkfront_info *info)
602 {
603 int notify;
604
605 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
606
607 if (notify)
608 notify_remote_via_irq(info->irq);
609 }
610
611 static inline bool blkif_request_flush_invalid(struct request *req,
612 struct blkfront_info *info)
613 {
614 return ((req->cmd_type != REQ_TYPE_FS) ||
615 ((req->cmd_flags & REQ_FLUSH) &&
616 !(info->feature_flush & REQ_FLUSH)) ||
617 ((req->cmd_flags & REQ_FUA) &&
618 !(info->feature_flush & REQ_FUA)));
619 }
620
621 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
622 const struct blk_mq_queue_data *qd)
623 {
624 struct blkfront_info *info = qd->rq->rq_disk->private_data;
625
626 blk_mq_start_request(qd->rq);
627 spin_lock_irq(&info->io_lock);
628 if (RING_FULL(&info->ring))
629 goto out_busy;
630
631 if (blkif_request_flush_invalid(qd->rq, info))
632 goto out_err;
633
634 if (blkif_queue_request(qd->rq))
635 goto out_busy;
636
637 flush_requests(info);
638 spin_unlock_irq(&info->io_lock);
639 return BLK_MQ_RQ_QUEUE_OK;
640
641 out_err:
642 spin_unlock_irq(&info->io_lock);
643 return BLK_MQ_RQ_QUEUE_ERROR;
644
645 out_busy:
646 spin_unlock_irq(&info->io_lock);
647 blk_mq_stop_hw_queue(hctx);
648 return BLK_MQ_RQ_QUEUE_BUSY;
649 }
650
651 static struct blk_mq_ops blkfront_mq_ops = {
652 .queue_rq = blkif_queue_rq,
653 .map_queue = blk_mq_map_queue,
654 };
655
656 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
657 unsigned int physical_sector_size,
658 unsigned int segments)
659 {
660 struct request_queue *rq;
661 struct blkfront_info *info = gd->private_data;
662
663 memset(&info->tag_set, 0, sizeof(info->tag_set));
664 info->tag_set.ops = &blkfront_mq_ops;
665 info->tag_set.nr_hw_queues = 1;
666 info->tag_set.queue_depth = BLK_RING_SIZE(info);
667 info->tag_set.numa_node = NUMA_NO_NODE;
668 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
669 info->tag_set.cmd_size = 0;
670 info->tag_set.driver_data = info;
671
672 if (blk_mq_alloc_tag_set(&info->tag_set))
673 return -1;
674 rq = blk_mq_init_queue(&info->tag_set);
675 if (IS_ERR(rq)) {
676 blk_mq_free_tag_set(&info->tag_set);
677 return -1;
678 }
679
680 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
681
682 if (info->feature_discard) {
683 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
684 blk_queue_max_discard_sectors(rq, get_capacity(gd));
685 rq->limits.discard_granularity = info->discard_granularity;
686 rq->limits.discard_alignment = info->discard_alignment;
687 if (info->feature_secdiscard)
688 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
689 }
690
691 /* Hard sector size and max sectors impersonate the equiv. hardware. */
692 blk_queue_logical_block_size(rq, sector_size);
693 blk_queue_physical_block_size(rq, physical_sector_size);
694 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512);
695
696 /* Each segment in a request is up to an aligned page in size. */
697 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
698 blk_queue_max_segment_size(rq, PAGE_SIZE);
699
700 /* Ensure a merged request will fit in a single I/O ring slot. */
701 blk_queue_max_segments(rq, segments);
702
703 /* Make sure buffer addresses are sector-aligned. */
704 blk_queue_dma_alignment(rq, 511);
705
706 /* Make sure we don't use bounce buffers. */
707 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
708
709 gd->queue = rq;
710
711 return 0;
712 }
713
714 static const char *flush_info(unsigned int feature_flush)
715 {
716 switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) {
717 case REQ_FLUSH|REQ_FUA:
718 return "barrier: enabled;";
719 case REQ_FLUSH:
720 return "flush diskcache: enabled;";
721 default:
722 return "barrier or flush: disabled;";
723 }
724 }
725
726 static void xlvbd_flush(struct blkfront_info *info)
727 {
728 blk_queue_flush(info->rq, info->feature_flush);
729 pr_info("blkfront: %s: %s %s %s %s %s\n",
730 info->gd->disk_name, flush_info(info->feature_flush),
731 "persistent grants:", info->feature_persistent ?
732 "enabled;" : "disabled;", "indirect descriptors:",
733 info->max_indirect_segments ? "enabled;" : "disabled;");
734 }
735
736 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
737 {
738 int major;
739 major = BLKIF_MAJOR(vdevice);
740 *minor = BLKIF_MINOR(vdevice);
741 switch (major) {
742 case XEN_IDE0_MAJOR:
743 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
744 *minor = ((*minor / 64) * PARTS_PER_DISK) +
745 EMULATED_HD_DISK_MINOR_OFFSET;
746 break;
747 case XEN_IDE1_MAJOR:
748 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
749 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
750 EMULATED_HD_DISK_MINOR_OFFSET;
751 break;
752 case XEN_SCSI_DISK0_MAJOR:
753 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
754 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
755 break;
756 case XEN_SCSI_DISK1_MAJOR:
757 case XEN_SCSI_DISK2_MAJOR:
758 case XEN_SCSI_DISK3_MAJOR:
759 case XEN_SCSI_DISK4_MAJOR:
760 case XEN_SCSI_DISK5_MAJOR:
761 case XEN_SCSI_DISK6_MAJOR:
762 case XEN_SCSI_DISK7_MAJOR:
763 *offset = (*minor / PARTS_PER_DISK) +
764 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
765 EMULATED_SD_DISK_NAME_OFFSET;
766 *minor = *minor +
767 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
768 EMULATED_SD_DISK_MINOR_OFFSET;
769 break;
770 case XEN_SCSI_DISK8_MAJOR:
771 case XEN_SCSI_DISK9_MAJOR:
772 case XEN_SCSI_DISK10_MAJOR:
773 case XEN_SCSI_DISK11_MAJOR:
774 case XEN_SCSI_DISK12_MAJOR:
775 case XEN_SCSI_DISK13_MAJOR:
776 case XEN_SCSI_DISK14_MAJOR:
777 case XEN_SCSI_DISK15_MAJOR:
778 *offset = (*minor / PARTS_PER_DISK) +
779 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
780 EMULATED_SD_DISK_NAME_OFFSET;
781 *minor = *minor +
782 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
783 EMULATED_SD_DISK_MINOR_OFFSET;
784 break;
785 case XENVBD_MAJOR:
786 *offset = *minor / PARTS_PER_DISK;
787 break;
788 default:
789 printk(KERN_WARNING "blkfront: your disk configuration is "
790 "incorrect, please use an xvd device instead\n");
791 return -ENODEV;
792 }
793 return 0;
794 }
795
796 static char *encode_disk_name(char *ptr, unsigned int n)
797 {
798 if (n >= 26)
799 ptr = encode_disk_name(ptr, n / 26 - 1);
800 *ptr = 'a' + n % 26;
801 return ptr + 1;
802 }
803
804 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
805 struct blkfront_info *info,
806 u16 vdisk_info, u16 sector_size,
807 unsigned int physical_sector_size)
808 {
809 struct gendisk *gd;
810 int nr_minors = 1;
811 int err;
812 unsigned int offset;
813 int minor;
814 int nr_parts;
815 char *ptr;
816
817 BUG_ON(info->gd != NULL);
818 BUG_ON(info->rq != NULL);
819
820 if ((info->vdevice>>EXT_SHIFT) > 1) {
821 /* this is above the extended range; something is wrong */
822 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
823 return -ENODEV;
824 }
825
826 if (!VDEV_IS_EXTENDED(info->vdevice)) {
827 err = xen_translate_vdev(info->vdevice, &minor, &offset);
828 if (err)
829 return err;
830 nr_parts = PARTS_PER_DISK;
831 } else {
832 minor = BLKIF_MINOR_EXT(info->vdevice);
833 nr_parts = PARTS_PER_EXT_DISK;
834 offset = minor / nr_parts;
835 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
836 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
837 "emulated IDE disks,\n\t choose an xvd device name"
838 "from xvde on\n", info->vdevice);
839 }
840 if (minor >> MINORBITS) {
841 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
842 info->vdevice, minor);
843 return -ENODEV;
844 }
845
846 if ((minor % nr_parts) == 0)
847 nr_minors = nr_parts;
848
849 err = xlbd_reserve_minors(minor, nr_minors);
850 if (err)
851 goto out;
852 err = -ENODEV;
853
854 gd = alloc_disk(nr_minors);
855 if (gd == NULL)
856 goto release;
857
858 strcpy(gd->disk_name, DEV_NAME);
859 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
860 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
861 if (nr_minors > 1)
862 *ptr = 0;
863 else
864 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
865 "%d", minor & (nr_parts - 1));
866
867 gd->major = XENVBD_MAJOR;
868 gd->first_minor = minor;
869 gd->fops = &xlvbd_block_fops;
870 gd->private_data = info;
871 gd->driverfs_dev = &(info->xbdev->dev);
872 set_capacity(gd, capacity);
873
874 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
875 info->max_indirect_segments ? :
876 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
877 del_gendisk(gd);
878 goto release;
879 }
880
881 info->rq = gd->queue;
882 info->gd = gd;
883
884 xlvbd_flush(info);
885
886 if (vdisk_info & VDISK_READONLY)
887 set_disk_ro(gd, 1);
888
889 if (vdisk_info & VDISK_REMOVABLE)
890 gd->flags |= GENHD_FL_REMOVABLE;
891
892 if (vdisk_info & VDISK_CDROM)
893 gd->flags |= GENHD_FL_CD;
894
895 return 0;
896
897 release:
898 xlbd_release_minors(minor, nr_minors);
899 out:
900 return err;
901 }
902
903 static void xlvbd_release_gendisk(struct blkfront_info *info)
904 {
905 unsigned int minor, nr_minors;
906
907 if (info->rq == NULL)
908 return;
909
910 /* No more blkif_request(). */
911 blk_mq_stop_hw_queues(info->rq);
912
913 /* No more gnttab callback work. */
914 gnttab_cancel_free_callback(&info->callback);
915
916 /* Flush gnttab callback work. Must be done with no locks held. */
917 flush_work(&info->work);
918
919 del_gendisk(info->gd);
920
921 minor = info->gd->first_minor;
922 nr_minors = info->gd->minors;
923 xlbd_release_minors(minor, nr_minors);
924
925 blk_cleanup_queue(info->rq);
926 blk_mq_free_tag_set(&info->tag_set);
927 info->rq = NULL;
928
929 put_disk(info->gd);
930 info->gd = NULL;
931 }
932
933 /* Must be called with io_lock holded */
934 static void kick_pending_request_queues(struct blkfront_info *info)
935 {
936 if (!RING_FULL(&info->ring))
937 blk_mq_start_stopped_hw_queues(info->rq, true);
938 }
939
940 static void blkif_restart_queue(struct work_struct *work)
941 {
942 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
943
944 spin_lock_irq(&info->io_lock);
945 if (info->connected == BLKIF_STATE_CONNECTED)
946 kick_pending_request_queues(info);
947 spin_unlock_irq(&info->io_lock);
948 }
949
950 static void blkif_free(struct blkfront_info *info, int suspend)
951 {
952 struct grant *persistent_gnt;
953 struct grant *n;
954 int i, j, segs;
955
956 /* Prevent new requests being issued until we fix things up. */
957 spin_lock_irq(&info->io_lock);
958 info->connected = suspend ?
959 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
960 /* No more blkif_request(). */
961 if (info->rq)
962 blk_mq_stop_hw_queues(info->rq);
963
964 /* Remove all persistent grants */
965 if (!list_empty(&info->grants)) {
966 list_for_each_entry_safe(persistent_gnt, n,
967 &info->grants, node) {
968 list_del(&persistent_gnt->node);
969 if (persistent_gnt->gref != GRANT_INVALID_REF) {
970 gnttab_end_foreign_access(persistent_gnt->gref,
971 0, 0UL);
972 info->persistent_gnts_c--;
973 }
974 if (info->feature_persistent)
975 __free_page(pfn_to_page(persistent_gnt->pfn));
976 kfree(persistent_gnt);
977 }
978 }
979 BUG_ON(info->persistent_gnts_c != 0);
980
981 /*
982 * Remove indirect pages, this only happens when using indirect
983 * descriptors but not persistent grants
984 */
985 if (!list_empty(&info->indirect_pages)) {
986 struct page *indirect_page, *n;
987
988 BUG_ON(info->feature_persistent);
989 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
990 list_del(&indirect_page->lru);
991 __free_page(indirect_page);
992 }
993 }
994
995 for (i = 0; i < BLK_RING_SIZE(info); i++) {
996 /*
997 * Clear persistent grants present in requests already
998 * on the shared ring
999 */
1000 if (!info->shadow[i].request)
1001 goto free_shadow;
1002
1003 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1004 info->shadow[i].req.u.indirect.nr_segments :
1005 info->shadow[i].req.u.rw.nr_segments;
1006 for (j = 0; j < segs; j++) {
1007 persistent_gnt = info->shadow[i].grants_used[j];
1008 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1009 if (info->feature_persistent)
1010 __free_page(pfn_to_page(persistent_gnt->pfn));
1011 kfree(persistent_gnt);
1012 }
1013
1014 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1015 /*
1016 * If this is not an indirect operation don't try to
1017 * free indirect segments
1018 */
1019 goto free_shadow;
1020
1021 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1022 persistent_gnt = info->shadow[i].indirect_grants[j];
1023 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1024 __free_page(pfn_to_page(persistent_gnt->pfn));
1025 kfree(persistent_gnt);
1026 }
1027
1028 free_shadow:
1029 kfree(info->shadow[i].grants_used);
1030 info->shadow[i].grants_used = NULL;
1031 kfree(info->shadow[i].indirect_grants);
1032 info->shadow[i].indirect_grants = NULL;
1033 kfree(info->shadow[i].sg);
1034 info->shadow[i].sg = NULL;
1035 }
1036
1037 /* No more gnttab callback work. */
1038 gnttab_cancel_free_callback(&info->callback);
1039 spin_unlock_irq(&info->io_lock);
1040
1041 /* Flush gnttab callback work. Must be done with no locks held. */
1042 flush_work(&info->work);
1043
1044 /* Free resources associated with old device channel. */
1045 for (i = 0; i < info->nr_ring_pages; i++) {
1046 if (info->ring_ref[i] != GRANT_INVALID_REF) {
1047 gnttab_end_foreign_access(info->ring_ref[i], 0, 0);
1048 info->ring_ref[i] = GRANT_INVALID_REF;
1049 }
1050 }
1051 free_pages((unsigned long)info->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE));
1052 info->ring.sring = NULL;
1053
1054 if (info->irq)
1055 unbind_from_irqhandler(info->irq, info);
1056 info->evtchn = info->irq = 0;
1057
1058 }
1059
1060 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
1061 struct blkif_response *bret)
1062 {
1063 int i = 0;
1064 struct scatterlist *sg;
1065 char *bvec_data;
1066 void *shared_data;
1067 int nseg;
1068
1069 nseg = s->req.operation == BLKIF_OP_INDIRECT ?
1070 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1071
1072 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1073 for_each_sg(s->sg, sg, nseg, i) {
1074 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1075 shared_data = kmap_atomic(
1076 pfn_to_page(s->grants_used[i]->pfn));
1077 bvec_data = kmap_atomic(sg_page(sg));
1078 memcpy(bvec_data + sg->offset,
1079 shared_data + sg->offset,
1080 sg->length);
1081 kunmap_atomic(bvec_data);
1082 kunmap_atomic(shared_data);
1083 }
1084 }
1085 /* Add the persistent grant into the list of free grants */
1086 for (i = 0; i < nseg; i++) {
1087 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1088 /*
1089 * If the grant is still mapped by the backend (the
1090 * backend has chosen to make this grant persistent)
1091 * we add it at the head of the list, so it will be
1092 * reused first.
1093 */
1094 if (!info->feature_persistent)
1095 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1096 s->grants_used[i]->gref);
1097 list_add(&s->grants_used[i]->node, &info->grants);
1098 info->persistent_gnts_c++;
1099 } else {
1100 /*
1101 * If the grant is not mapped by the backend we end the
1102 * foreign access and add it to the tail of the list,
1103 * so it will not be picked again unless we run out of
1104 * persistent grants.
1105 */
1106 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1107 s->grants_used[i]->gref = GRANT_INVALID_REF;
1108 list_add_tail(&s->grants_used[i]->node, &info->grants);
1109 }
1110 }
1111 if (s->req.operation == BLKIF_OP_INDIRECT) {
1112 for (i = 0; i < INDIRECT_GREFS(nseg); i++) {
1113 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1114 if (!info->feature_persistent)
1115 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1116 s->indirect_grants[i]->gref);
1117 list_add(&s->indirect_grants[i]->node, &info->grants);
1118 info->persistent_gnts_c++;
1119 } else {
1120 struct page *indirect_page;
1121
1122 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1123 /*
1124 * Add the used indirect page back to the list of
1125 * available pages for indirect grefs.
1126 */
1127 if (!info->feature_persistent) {
1128 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
1129 list_add(&indirect_page->lru, &info->indirect_pages);
1130 }
1131 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1132 list_add_tail(&s->indirect_grants[i]->node, &info->grants);
1133 }
1134 }
1135 }
1136 }
1137
1138 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1139 {
1140 struct request *req;
1141 struct blkif_response *bret;
1142 RING_IDX i, rp;
1143 unsigned long flags;
1144 struct blkfront_info *info = (struct blkfront_info *)dev_id;
1145
1146 spin_lock_irqsave(&info->io_lock, flags);
1147
1148 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1149 spin_unlock_irqrestore(&info->io_lock, flags);
1150 return IRQ_HANDLED;
1151 }
1152
1153 again:
1154 rp = info->ring.sring->rsp_prod;
1155 rmb(); /* Ensure we see queued responses up to 'rp'. */
1156
1157 for (i = info->ring.rsp_cons; i != rp; i++) {
1158 unsigned long id;
1159
1160 bret = RING_GET_RESPONSE(&info->ring, i);
1161 id = bret->id;
1162 /*
1163 * The backend has messed up and given us an id that we would
1164 * never have given to it (we stamp it up to BLK_RING_SIZE -
1165 * look in get_id_from_freelist.
1166 */
1167 if (id >= BLK_RING_SIZE(info)) {
1168 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1169 info->gd->disk_name, op_name(bret->operation), id);
1170 /* We can't safely get the 'struct request' as
1171 * the id is busted. */
1172 continue;
1173 }
1174 req = info->shadow[id].request;
1175
1176 if (bret->operation != BLKIF_OP_DISCARD)
1177 blkif_completion(&info->shadow[id], info, bret);
1178
1179 if (add_id_to_freelist(info, id)) {
1180 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1181 info->gd->disk_name, op_name(bret->operation), id);
1182 continue;
1183 }
1184
1185 req->errors = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1186 switch (bret->operation) {
1187 case BLKIF_OP_DISCARD:
1188 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1189 struct request_queue *rq = info->rq;
1190 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1191 info->gd->disk_name, op_name(bret->operation));
1192 req->errors = -EOPNOTSUPP;
1193 info->feature_discard = 0;
1194 info->feature_secdiscard = 0;
1195 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1196 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1197 }
1198 blk_mq_complete_request(req);
1199 break;
1200 case BLKIF_OP_FLUSH_DISKCACHE:
1201 case BLKIF_OP_WRITE_BARRIER:
1202 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1203 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1204 info->gd->disk_name, op_name(bret->operation));
1205 req->errors = -EOPNOTSUPP;
1206 }
1207 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1208 info->shadow[id].req.u.rw.nr_segments == 0)) {
1209 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1210 info->gd->disk_name, op_name(bret->operation));
1211 req->errors = -EOPNOTSUPP;
1212 }
1213 if (unlikely(req->errors)) {
1214 if (req->errors == -EOPNOTSUPP)
1215 req->errors = 0;
1216 info->feature_flush = 0;
1217 xlvbd_flush(info);
1218 }
1219 /* fall through */
1220 case BLKIF_OP_READ:
1221 case BLKIF_OP_WRITE:
1222 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1223 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1224 "request: %x\n", bret->status);
1225
1226 blk_mq_complete_request(req);
1227 break;
1228 default:
1229 BUG();
1230 }
1231 }
1232
1233 info->ring.rsp_cons = i;
1234
1235 if (i != info->ring.req_prod_pvt) {
1236 int more_to_do;
1237 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
1238 if (more_to_do)
1239 goto again;
1240 } else
1241 info->ring.sring->rsp_event = i + 1;
1242
1243 kick_pending_request_queues(info);
1244
1245 spin_unlock_irqrestore(&info->io_lock, flags);
1246
1247 return IRQ_HANDLED;
1248 }
1249
1250
1251 static int setup_blkring(struct xenbus_device *dev,
1252 struct blkfront_info *info)
1253 {
1254 struct blkif_sring *sring;
1255 int err, i;
1256 unsigned long ring_size = info->nr_ring_pages * PAGE_SIZE;
1257 grant_ref_t gref[XENBUS_MAX_RING_PAGES];
1258
1259 for (i = 0; i < info->nr_ring_pages; i++)
1260 info->ring_ref[i] = GRANT_INVALID_REF;
1261
1262 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1263 get_order(ring_size));
1264 if (!sring) {
1265 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1266 return -ENOMEM;
1267 }
1268 SHARED_RING_INIT(sring);
1269 FRONT_RING_INIT(&info->ring, sring, ring_size);
1270
1271 err = xenbus_grant_ring(dev, info->ring.sring, info->nr_ring_pages, gref);
1272 if (err < 0) {
1273 free_pages((unsigned long)sring, get_order(ring_size));
1274 info->ring.sring = NULL;
1275 goto fail;
1276 }
1277 for (i = 0; i < info->nr_ring_pages; i++)
1278 info->ring_ref[i] = gref[i];
1279
1280 err = xenbus_alloc_evtchn(dev, &info->evtchn);
1281 if (err)
1282 goto fail;
1283
1284 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
1285 "blkif", info);
1286 if (err <= 0) {
1287 xenbus_dev_fatal(dev, err,
1288 "bind_evtchn_to_irqhandler failed");
1289 goto fail;
1290 }
1291 info->irq = err;
1292
1293 return 0;
1294 fail:
1295 blkif_free(info, 0);
1296 return err;
1297 }
1298
1299
1300 /* Common code used when first setting up, and when resuming. */
1301 static int talk_to_blkback(struct xenbus_device *dev,
1302 struct blkfront_info *info)
1303 {
1304 const char *message = NULL;
1305 struct xenbus_transaction xbt;
1306 int err, i;
1307 unsigned int max_page_order = 0;
1308 unsigned int ring_page_order = 0;
1309
1310 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1311 "max-ring-page-order", "%u", &max_page_order);
1312 if (err != 1)
1313 info->nr_ring_pages = 1;
1314 else {
1315 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1316 info->nr_ring_pages = 1 << ring_page_order;
1317 }
1318
1319 /* Create shared ring, alloc event channel. */
1320 err = setup_blkring(dev, info);
1321 if (err)
1322 goto out;
1323
1324 again:
1325 err = xenbus_transaction_start(&xbt);
1326 if (err) {
1327 xenbus_dev_fatal(dev, err, "starting transaction");
1328 goto destroy_blkring;
1329 }
1330
1331 if (info->nr_ring_pages == 1) {
1332 err = xenbus_printf(xbt, dev->nodename,
1333 "ring-ref", "%u", info->ring_ref[0]);
1334 if (err) {
1335 message = "writing ring-ref";
1336 goto abort_transaction;
1337 }
1338 } else {
1339 err = xenbus_printf(xbt, dev->nodename,
1340 "ring-page-order", "%u", ring_page_order);
1341 if (err) {
1342 message = "writing ring-page-order";
1343 goto abort_transaction;
1344 }
1345
1346 for (i = 0; i < info->nr_ring_pages; i++) {
1347 char ring_ref_name[RINGREF_NAME_LEN];
1348
1349 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1350 err = xenbus_printf(xbt, dev->nodename, ring_ref_name,
1351 "%u", info->ring_ref[i]);
1352 if (err) {
1353 message = "writing ring-ref";
1354 goto abort_transaction;
1355 }
1356 }
1357 }
1358 err = xenbus_printf(xbt, dev->nodename,
1359 "event-channel", "%u", info->evtchn);
1360 if (err) {
1361 message = "writing event-channel";
1362 goto abort_transaction;
1363 }
1364 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1365 XEN_IO_PROTO_ABI_NATIVE);
1366 if (err) {
1367 message = "writing protocol";
1368 goto abort_transaction;
1369 }
1370 err = xenbus_printf(xbt, dev->nodename,
1371 "feature-persistent", "%u", 1);
1372 if (err)
1373 dev_warn(&dev->dev,
1374 "writing persistent grants feature to xenbus");
1375
1376 err = xenbus_transaction_end(xbt, 0);
1377 if (err) {
1378 if (err == -EAGAIN)
1379 goto again;
1380 xenbus_dev_fatal(dev, err, "completing transaction");
1381 goto destroy_blkring;
1382 }
1383
1384 for (i = 0; i < BLK_RING_SIZE(info); i++)
1385 info->shadow[i].req.u.rw.id = i+1;
1386 info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1387 xenbus_switch_state(dev, XenbusStateInitialised);
1388
1389 return 0;
1390
1391 abort_transaction:
1392 xenbus_transaction_end(xbt, 1);
1393 if (message)
1394 xenbus_dev_fatal(dev, err, "%s", message);
1395 destroy_blkring:
1396 blkif_free(info, 0);
1397 out:
1398 return err;
1399 }
1400
1401 /**
1402 * Entry point to this code when a new device is created. Allocate the basic
1403 * structures and the ring buffer for communication with the backend, and
1404 * inform the backend of the appropriate details for those. Switch to
1405 * Initialised state.
1406 */
1407 static int blkfront_probe(struct xenbus_device *dev,
1408 const struct xenbus_device_id *id)
1409 {
1410 int err, vdevice;
1411 struct blkfront_info *info;
1412
1413 /* FIXME: Use dynamic device id if this is not set. */
1414 err = xenbus_scanf(XBT_NIL, dev->nodename,
1415 "virtual-device", "%i", &vdevice);
1416 if (err != 1) {
1417 /* go looking in the extended area instead */
1418 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1419 "%i", &vdevice);
1420 if (err != 1) {
1421 xenbus_dev_fatal(dev, err, "reading virtual-device");
1422 return err;
1423 }
1424 }
1425
1426 if (xen_hvm_domain()) {
1427 char *type;
1428 int len;
1429 /* no unplug has been done: do not hook devices != xen vbds */
1430 if (xen_has_pv_and_legacy_disk_devices()) {
1431 int major;
1432
1433 if (!VDEV_IS_EXTENDED(vdevice))
1434 major = BLKIF_MAJOR(vdevice);
1435 else
1436 major = XENVBD_MAJOR;
1437
1438 if (major != XENVBD_MAJOR) {
1439 printk(KERN_INFO
1440 "%s: HVM does not support vbd %d as xen block device\n",
1441 __func__, vdevice);
1442 return -ENODEV;
1443 }
1444 }
1445 /* do not create a PV cdrom device if we are an HVM guest */
1446 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1447 if (IS_ERR(type))
1448 return -ENODEV;
1449 if (strncmp(type, "cdrom", 5) == 0) {
1450 kfree(type);
1451 return -ENODEV;
1452 }
1453 kfree(type);
1454 }
1455 info = kzalloc(sizeof(*info), GFP_KERNEL);
1456 if (!info) {
1457 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1458 return -ENOMEM;
1459 }
1460
1461 mutex_init(&info->mutex);
1462 spin_lock_init(&info->io_lock);
1463 info->xbdev = dev;
1464 info->vdevice = vdevice;
1465 INIT_LIST_HEAD(&info->grants);
1466 INIT_LIST_HEAD(&info->indirect_pages);
1467 info->persistent_gnts_c = 0;
1468 info->connected = BLKIF_STATE_DISCONNECTED;
1469 INIT_WORK(&info->work, blkif_restart_queue);
1470
1471 /* Front end dir is a number, which is used as the id. */
1472 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1473 dev_set_drvdata(&dev->dev, info);
1474
1475 return 0;
1476 }
1477
1478 static void split_bio_end(struct bio *bio)
1479 {
1480 struct split_bio *split_bio = bio->bi_private;
1481
1482 if (atomic_dec_and_test(&split_bio->pending)) {
1483 split_bio->bio->bi_phys_segments = 0;
1484 split_bio->bio->bi_error = bio->bi_error;
1485 bio_endio(split_bio->bio);
1486 kfree(split_bio);
1487 }
1488 bio_put(bio);
1489 }
1490
1491 static int blkif_recover(struct blkfront_info *info)
1492 {
1493 int i;
1494 struct request *req, *n;
1495 struct blk_shadow *copy;
1496 int rc;
1497 struct bio *bio, *cloned_bio;
1498 struct bio_list bio_list, merge_bio;
1499 unsigned int segs, offset;
1500 int pending, size;
1501 struct split_bio *split_bio;
1502 struct list_head requests;
1503
1504 /* Stage 1: Make a safe copy of the shadow state. */
1505 copy = kmemdup(info->shadow, sizeof(info->shadow),
1506 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1507 if (!copy)
1508 return -ENOMEM;
1509
1510 /* Stage 2: Set up free list. */
1511 memset(&info->shadow, 0, sizeof(info->shadow));
1512 for (i = 0; i < BLK_RING_SIZE(info); i++)
1513 info->shadow[i].req.u.rw.id = i+1;
1514 info->shadow_free = info->ring.req_prod_pvt;
1515 info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1516
1517 rc = blkfront_gather_backend_features(info);
1518 if (rc) {
1519 kfree(copy);
1520 return rc;
1521 }
1522
1523 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
1524 blk_queue_max_segments(info->rq, segs);
1525 bio_list_init(&bio_list);
1526 INIT_LIST_HEAD(&requests);
1527 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1528 /* Not in use? */
1529 if (!copy[i].request)
1530 continue;
1531
1532 /*
1533 * Get the bios in the request so we can re-queue them.
1534 */
1535 if (copy[i].request->cmd_flags &
1536 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1537 /*
1538 * Flush operations don't contain bios, so
1539 * we need to requeue the whole request
1540 */
1541 list_add(&copy[i].request->queuelist, &requests);
1542 continue;
1543 }
1544 merge_bio.head = copy[i].request->bio;
1545 merge_bio.tail = copy[i].request->biotail;
1546 bio_list_merge(&bio_list, &merge_bio);
1547 copy[i].request->bio = NULL;
1548 blk_end_request_all(copy[i].request, 0);
1549 }
1550
1551 kfree(copy);
1552
1553 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1554
1555 spin_lock_irq(&info->io_lock);
1556
1557 /* Now safe for us to use the shared ring */
1558 info->connected = BLKIF_STATE_CONNECTED;
1559
1560 /* Kick any other new requests queued since we resumed */
1561 kick_pending_request_queues(info);
1562
1563 list_for_each_entry_safe(req, n, &requests, queuelist) {
1564 /* Requeue pending requests (flush or discard) */
1565 list_del_init(&req->queuelist);
1566 BUG_ON(req->nr_phys_segments > segs);
1567 blk_mq_requeue_request(req);
1568 }
1569 spin_unlock_irq(&info->io_lock);
1570 blk_mq_kick_requeue_list(info->rq);
1571
1572 while ((bio = bio_list_pop(&bio_list)) != NULL) {
1573 /* Traverse the list of pending bios and re-queue them */
1574 if (bio_segments(bio) > segs) {
1575 /*
1576 * This bio has more segments than what we can
1577 * handle, we have to split it.
1578 */
1579 pending = (bio_segments(bio) + segs - 1) / segs;
1580 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
1581 BUG_ON(split_bio == NULL);
1582 atomic_set(&split_bio->pending, pending);
1583 split_bio->bio = bio;
1584 for (i = 0; i < pending; i++) {
1585 offset = (i * segs * PAGE_SIZE) >> 9;
1586 size = min((unsigned int)(segs * PAGE_SIZE) >> 9,
1587 (unsigned int)bio_sectors(bio) - offset);
1588 cloned_bio = bio_clone(bio, GFP_NOIO);
1589 BUG_ON(cloned_bio == NULL);
1590 bio_trim(cloned_bio, offset, size);
1591 cloned_bio->bi_private = split_bio;
1592 cloned_bio->bi_end_io = split_bio_end;
1593 submit_bio(cloned_bio->bi_rw, cloned_bio);
1594 }
1595 /*
1596 * Now we have to wait for all those smaller bios to
1597 * end, so we can also end the "parent" bio.
1598 */
1599 continue;
1600 }
1601 /* We don't need to split this bio */
1602 submit_bio(bio->bi_rw, bio);
1603 }
1604
1605 return 0;
1606 }
1607
1608 /**
1609 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1610 * driver restart. We tear down our blkif structure and recreate it, but
1611 * leave the device-layer structures intact so that this is transparent to the
1612 * rest of the kernel.
1613 */
1614 static int blkfront_resume(struct xenbus_device *dev)
1615 {
1616 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1617 int err;
1618
1619 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1620
1621 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1622
1623 err = talk_to_blkback(dev, info);
1624
1625 /*
1626 * We have to wait for the backend to switch to
1627 * connected state, since we want to read which
1628 * features it supports.
1629 */
1630
1631 return err;
1632 }
1633
1634 static void
1635 blkfront_closing(struct blkfront_info *info)
1636 {
1637 struct xenbus_device *xbdev = info->xbdev;
1638 struct block_device *bdev = NULL;
1639
1640 mutex_lock(&info->mutex);
1641
1642 if (xbdev->state == XenbusStateClosing) {
1643 mutex_unlock(&info->mutex);
1644 return;
1645 }
1646
1647 if (info->gd)
1648 bdev = bdget_disk(info->gd, 0);
1649
1650 mutex_unlock(&info->mutex);
1651
1652 if (!bdev) {
1653 xenbus_frontend_closed(xbdev);
1654 return;
1655 }
1656
1657 mutex_lock(&bdev->bd_mutex);
1658
1659 if (bdev->bd_openers) {
1660 xenbus_dev_error(xbdev, -EBUSY,
1661 "Device in use; refusing to close");
1662 xenbus_switch_state(xbdev, XenbusStateClosing);
1663 } else {
1664 xlvbd_release_gendisk(info);
1665 xenbus_frontend_closed(xbdev);
1666 }
1667
1668 mutex_unlock(&bdev->bd_mutex);
1669 bdput(bdev);
1670 }
1671
1672 static void blkfront_setup_discard(struct blkfront_info *info)
1673 {
1674 int err;
1675 unsigned int discard_granularity;
1676 unsigned int discard_alignment;
1677 unsigned int discard_secure;
1678
1679 info->feature_discard = 1;
1680 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1681 "discard-granularity", "%u", &discard_granularity,
1682 "discard-alignment", "%u", &discard_alignment,
1683 NULL);
1684 if (!err) {
1685 info->discard_granularity = discard_granularity;
1686 info->discard_alignment = discard_alignment;
1687 }
1688 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1689 "discard-secure", "%d", &discard_secure,
1690 NULL);
1691 if (!err)
1692 info->feature_secdiscard = !!discard_secure;
1693 }
1694
1695 static int blkfront_setup_indirect(struct blkfront_info *info)
1696 {
1697 unsigned int segs;
1698 int err, i;
1699
1700 if (info->max_indirect_segments == 0)
1701 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
1702 else
1703 segs = info->max_indirect_segments;
1704
1705 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE(info));
1706 if (err)
1707 goto out_of_memory;
1708
1709 if (!info->feature_persistent && info->max_indirect_segments) {
1710 /*
1711 * We are using indirect descriptors but not persistent
1712 * grants, we need to allocate a set of pages that can be
1713 * used for mapping indirect grefs
1714 */
1715 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE(info);
1716
1717 BUG_ON(!list_empty(&info->indirect_pages));
1718 for (i = 0; i < num; i++) {
1719 struct page *indirect_page = alloc_page(GFP_NOIO);
1720 if (!indirect_page)
1721 goto out_of_memory;
1722 list_add(&indirect_page->lru, &info->indirect_pages);
1723 }
1724 }
1725
1726 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1727 info->shadow[i].grants_used = kzalloc(
1728 sizeof(info->shadow[i].grants_used[0]) * segs,
1729 GFP_NOIO);
1730 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO);
1731 if (info->max_indirect_segments)
1732 info->shadow[i].indirect_grants = kzalloc(
1733 sizeof(info->shadow[i].indirect_grants[0]) *
1734 INDIRECT_GREFS(segs),
1735 GFP_NOIO);
1736 if ((info->shadow[i].grants_used == NULL) ||
1737 (info->shadow[i].sg == NULL) ||
1738 (info->max_indirect_segments &&
1739 (info->shadow[i].indirect_grants == NULL)))
1740 goto out_of_memory;
1741 sg_init_table(info->shadow[i].sg, segs);
1742 }
1743
1744
1745 return 0;
1746
1747 out_of_memory:
1748 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1749 kfree(info->shadow[i].grants_used);
1750 info->shadow[i].grants_used = NULL;
1751 kfree(info->shadow[i].sg);
1752 info->shadow[i].sg = NULL;
1753 kfree(info->shadow[i].indirect_grants);
1754 info->shadow[i].indirect_grants = NULL;
1755 }
1756 if (!list_empty(&info->indirect_pages)) {
1757 struct page *indirect_page, *n;
1758 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
1759 list_del(&indirect_page->lru);
1760 __free_page(indirect_page);
1761 }
1762 }
1763 return -ENOMEM;
1764 }
1765
1766 /*
1767 * Gather all backend feature-*
1768 */
1769 static int blkfront_gather_backend_features(struct blkfront_info *info)
1770 {
1771 int err;
1772 int barrier, flush, discard, persistent;
1773 unsigned int indirect_segments;
1774
1775 info->feature_flush = 0;
1776
1777 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1778 "feature-barrier", "%d", &barrier,
1779 NULL);
1780
1781 /*
1782 * If there's no "feature-barrier" defined, then it means
1783 * we're dealing with a very old backend which writes
1784 * synchronously; nothing to do.
1785 *
1786 * If there are barriers, then we use flush.
1787 */
1788 if (!err && barrier)
1789 info->feature_flush = REQ_FLUSH | REQ_FUA;
1790 /*
1791 * And if there is "feature-flush-cache" use that above
1792 * barriers.
1793 */
1794 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1795 "feature-flush-cache", "%d", &flush,
1796 NULL);
1797
1798 if (!err && flush)
1799 info->feature_flush = REQ_FLUSH;
1800
1801 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1802 "feature-discard", "%d", &discard,
1803 NULL);
1804
1805 if (!err && discard)
1806 blkfront_setup_discard(info);
1807
1808 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1809 "feature-persistent", "%u", &persistent,
1810 NULL);
1811 if (err)
1812 info->feature_persistent = 0;
1813 else
1814 info->feature_persistent = persistent;
1815
1816 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1817 "feature-max-indirect-segments", "%u", &indirect_segments,
1818 NULL);
1819 if (err)
1820 info->max_indirect_segments = 0;
1821 else
1822 info->max_indirect_segments = min(indirect_segments,
1823 xen_blkif_max_segments);
1824
1825 return blkfront_setup_indirect(info);
1826 }
1827
1828 /*
1829 * Invoked when the backend is finally 'ready' (and has told produced
1830 * the details about the physical device - #sectors, size, etc).
1831 */
1832 static void blkfront_connect(struct blkfront_info *info)
1833 {
1834 unsigned long long sectors;
1835 unsigned long sector_size;
1836 unsigned int physical_sector_size;
1837 unsigned int binfo;
1838 int err;
1839
1840 switch (info->connected) {
1841 case BLKIF_STATE_CONNECTED:
1842 /*
1843 * Potentially, the back-end may be signalling
1844 * a capacity change; update the capacity.
1845 */
1846 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1847 "sectors", "%Lu", &sectors);
1848 if (XENBUS_EXIST_ERR(err))
1849 return;
1850 printk(KERN_INFO "Setting capacity to %Lu\n",
1851 sectors);
1852 set_capacity(info->gd, sectors);
1853 revalidate_disk(info->gd);
1854
1855 return;
1856 case BLKIF_STATE_SUSPENDED:
1857 /*
1858 * If we are recovering from suspension, we need to wait
1859 * for the backend to announce it's features before
1860 * reconnecting, at least we need to know if the backend
1861 * supports indirect descriptors, and how many.
1862 */
1863 blkif_recover(info);
1864 return;
1865
1866 default:
1867 break;
1868 }
1869
1870 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1871 __func__, info->xbdev->otherend);
1872
1873 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1874 "sectors", "%llu", &sectors,
1875 "info", "%u", &binfo,
1876 "sector-size", "%lu", &sector_size,
1877 NULL);
1878 if (err) {
1879 xenbus_dev_fatal(info->xbdev, err,
1880 "reading backend fields at %s",
1881 info->xbdev->otherend);
1882 return;
1883 }
1884
1885 /*
1886 * physcial-sector-size is a newer field, so old backends may not
1887 * provide this. Assume physical sector size to be the same as
1888 * sector_size in that case.
1889 */
1890 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1891 "physical-sector-size", "%u", &physical_sector_size);
1892 if (err != 1)
1893 physical_sector_size = sector_size;
1894
1895 err = blkfront_gather_backend_features(info);
1896 if (err) {
1897 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
1898 info->xbdev->otherend);
1899 return;
1900 }
1901
1902 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
1903 physical_sector_size);
1904 if (err) {
1905 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1906 info->xbdev->otherend);
1907 return;
1908 }
1909
1910 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1911
1912 /* Kick pending requests. */
1913 spin_lock_irq(&info->io_lock);
1914 info->connected = BLKIF_STATE_CONNECTED;
1915 kick_pending_request_queues(info);
1916 spin_unlock_irq(&info->io_lock);
1917
1918 add_disk(info->gd);
1919
1920 info->is_ready = 1;
1921 }
1922
1923 /**
1924 * Callback received when the backend's state changes.
1925 */
1926 static void blkback_changed(struct xenbus_device *dev,
1927 enum xenbus_state backend_state)
1928 {
1929 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1930
1931 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1932
1933 switch (backend_state) {
1934 case XenbusStateInitWait:
1935 if (dev->state != XenbusStateInitialising)
1936 break;
1937 if (talk_to_blkback(dev, info)) {
1938 kfree(info);
1939 dev_set_drvdata(&dev->dev, NULL);
1940 break;
1941 }
1942 case XenbusStateInitialising:
1943 case XenbusStateInitialised:
1944 case XenbusStateReconfiguring:
1945 case XenbusStateReconfigured:
1946 case XenbusStateUnknown:
1947 break;
1948
1949 case XenbusStateConnected:
1950 blkfront_connect(info);
1951 break;
1952
1953 case XenbusStateClosed:
1954 if (dev->state == XenbusStateClosed)
1955 break;
1956 /* Missed the backend's Closing state -- fallthrough */
1957 case XenbusStateClosing:
1958 blkfront_closing(info);
1959 break;
1960 }
1961 }
1962
1963 static int blkfront_remove(struct xenbus_device *xbdev)
1964 {
1965 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1966 struct block_device *bdev = NULL;
1967 struct gendisk *disk;
1968
1969 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1970
1971 blkif_free(info, 0);
1972
1973 mutex_lock(&info->mutex);
1974
1975 disk = info->gd;
1976 if (disk)
1977 bdev = bdget_disk(disk, 0);
1978
1979 info->xbdev = NULL;
1980 mutex_unlock(&info->mutex);
1981
1982 if (!bdev) {
1983 kfree(info);
1984 return 0;
1985 }
1986
1987 /*
1988 * The xbdev was removed before we reached the Closed
1989 * state. See if it's safe to remove the disk. If the bdev
1990 * isn't closed yet, we let release take care of it.
1991 */
1992
1993 mutex_lock(&bdev->bd_mutex);
1994 info = disk->private_data;
1995
1996 dev_warn(disk_to_dev(disk),
1997 "%s was hot-unplugged, %d stale handles\n",
1998 xbdev->nodename, bdev->bd_openers);
1999
2000 if (info && !bdev->bd_openers) {
2001 xlvbd_release_gendisk(info);
2002 disk->private_data = NULL;
2003 kfree(info);
2004 }
2005
2006 mutex_unlock(&bdev->bd_mutex);
2007 bdput(bdev);
2008
2009 return 0;
2010 }
2011
2012 static int blkfront_is_ready(struct xenbus_device *dev)
2013 {
2014 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2015
2016 return info->is_ready && info->xbdev;
2017 }
2018
2019 static int blkif_open(struct block_device *bdev, fmode_t mode)
2020 {
2021 struct gendisk *disk = bdev->bd_disk;
2022 struct blkfront_info *info;
2023 int err = 0;
2024
2025 mutex_lock(&blkfront_mutex);
2026
2027 info = disk->private_data;
2028 if (!info) {
2029 /* xbdev gone */
2030 err = -ERESTARTSYS;
2031 goto out;
2032 }
2033
2034 mutex_lock(&info->mutex);
2035
2036 if (!info->gd)
2037 /* xbdev is closed */
2038 err = -ERESTARTSYS;
2039
2040 mutex_unlock(&info->mutex);
2041
2042 out:
2043 mutex_unlock(&blkfront_mutex);
2044 return err;
2045 }
2046
2047 static void blkif_release(struct gendisk *disk, fmode_t mode)
2048 {
2049 struct blkfront_info *info = disk->private_data;
2050 struct block_device *bdev;
2051 struct xenbus_device *xbdev;
2052
2053 mutex_lock(&blkfront_mutex);
2054
2055 bdev = bdget_disk(disk, 0);
2056
2057 if (!bdev) {
2058 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2059 goto out_mutex;
2060 }
2061 if (bdev->bd_openers)
2062 goto out;
2063
2064 /*
2065 * Check if we have been instructed to close. We will have
2066 * deferred this request, because the bdev was still open.
2067 */
2068
2069 mutex_lock(&info->mutex);
2070 xbdev = info->xbdev;
2071
2072 if (xbdev && xbdev->state == XenbusStateClosing) {
2073 /* pending switch to state closed */
2074 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2075 xlvbd_release_gendisk(info);
2076 xenbus_frontend_closed(info->xbdev);
2077 }
2078
2079 mutex_unlock(&info->mutex);
2080
2081 if (!xbdev) {
2082 /* sudden device removal */
2083 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2084 xlvbd_release_gendisk(info);
2085 disk->private_data = NULL;
2086 kfree(info);
2087 }
2088
2089 out:
2090 bdput(bdev);
2091 out_mutex:
2092 mutex_unlock(&blkfront_mutex);
2093 }
2094
2095 static const struct block_device_operations xlvbd_block_fops =
2096 {
2097 .owner = THIS_MODULE,
2098 .open = blkif_open,
2099 .release = blkif_release,
2100 .getgeo = blkif_getgeo,
2101 .ioctl = blkif_ioctl,
2102 };
2103
2104
2105 static const struct xenbus_device_id blkfront_ids[] = {
2106 { "vbd" },
2107 { "" }
2108 };
2109
2110 static struct xenbus_driver blkfront_driver = {
2111 .ids = blkfront_ids,
2112 .probe = blkfront_probe,
2113 .remove = blkfront_remove,
2114 .resume = blkfront_resume,
2115 .otherend_changed = blkback_changed,
2116 .is_ready = blkfront_is_ready,
2117 };
2118
2119 static int __init xlblk_init(void)
2120 {
2121 int ret;
2122
2123 if (!xen_domain())
2124 return -ENODEV;
2125
2126 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER) {
2127 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2128 xen_blkif_max_ring_order, XENBUS_MAX_RING_PAGE_ORDER);
2129 xen_blkif_max_ring_order = 0;
2130 }
2131
2132 if (!xen_has_pv_disk_devices())
2133 return -ENODEV;
2134
2135 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2136 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2137 XENVBD_MAJOR, DEV_NAME);
2138 return -ENODEV;
2139 }
2140
2141 ret = xenbus_register_frontend(&blkfront_driver);
2142 if (ret) {
2143 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2144 return ret;
2145 }
2146
2147 return 0;
2148 }
2149 module_init(xlblk_init);
2150
2151
2152 static void __exit xlblk_exit(void)
2153 {
2154 xenbus_unregister_driver(&blkfront_driver);
2155 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2156 kfree(minors);
2157 }
2158 module_exit(xlblk_exit);
2159
2160 MODULE_DESCRIPTION("Xen virtual block device frontend");
2161 MODULE_LICENSE("GPL");
2162 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2163 MODULE_ALIAS("xen:vbd");
2164 MODULE_ALIAS("xenblk");
Linux kernel - Deliverables
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