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CRISv32: add unreachable() to BUG()
[linux/fpc-iii.git] / drivers / block / xen-blkfront.c
blob5f6b3be0a93cc0ba82c105f1c57a5b3ba4382aea
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 #include <linux/list.h>
48
49 #include <xen/xen.h>
50 #include <xen/xenbus.h>
51 #include <xen/grant_table.h>
52 #include <xen/events.h>
53 #include <xen/page.h>
54 #include <xen/platform_pci.h>
55
56 #include <xen/interface/grant_table.h>
57 #include <xen/interface/io/blkif.h>
58 #include <xen/interface/io/protocols.h>
59
60 #include <asm/xen/hypervisor.h>
61
62 enum blkif_state {
63 BLKIF_STATE_DISCONNECTED,
64 BLKIF_STATE_CONNECTED,
65 BLKIF_STATE_SUSPENDED,
66 };
67
68 struct grant {
69 grant_ref_t gref;
70 unsigned long pfn;
71 struct list_head node;
72 };
73
74 struct blk_shadow {
75 struct blkif_request req;
76 struct request *request;
77 struct grant **grants_used;
78 struct grant **indirect_grants;
79 struct scatterlist *sg;
80 };
81
82 struct split_bio {
83 struct bio *bio;
84 atomic_t pending;
85 };
86
87 static DEFINE_MUTEX(blkfront_mutex);
88 static const struct block_device_operations xlvbd_block_fops;
89
90 /*
91 * Maximum number of segments in indirect requests, the actual value used by
92 * the frontend driver is the minimum of this value and the value provided
93 * by the backend driver.
94 */
95
96 static unsigned int xen_blkif_max_segments = 32;
97 module_param_named(max, xen_blkif_max_segments, int, S_IRUGO);
98 MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)");
99
100 /*
101 * Maximum order of pages to be used for the shared ring between front and
102 * backend, 4KB page granularity is used.
103 */
104 static unsigned int xen_blkif_max_ring_order;
105 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO);
106 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
107
108 #define BLK_RING_SIZE(info) __CONST_RING_SIZE(blkif, PAGE_SIZE * (info)->nr_ring_pages)
109 #define BLK_MAX_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE * XENBUS_MAX_RING_PAGES)
110 /*
111 * ring-ref%i i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
112 * characters are enough. Define to 20 to keep consist with backend.
113 */
114 #define RINGREF_NAME_LEN (20)
115
116 /*
117 * We have one of these per vbd, whether ide, scsi or 'other'. They
118 * hang in private_data off the gendisk structure. We may end up
119 * putting all kinds of interesting stuff here :-)
120 */
121 struct blkfront_info
122 {
123 spinlock_t io_lock;
124 struct mutex mutex;
125 struct xenbus_device *xbdev;
126 struct gendisk *gd;
127 int vdevice;
128 blkif_vdev_t handle;
129 enum blkif_state connected;
130 int ring_ref[XENBUS_MAX_RING_PAGES];
131 unsigned int nr_ring_pages;
132 struct blkif_front_ring ring;
133 unsigned int evtchn, irq;
134 struct request_queue *rq;
135 struct work_struct work;
136 struct gnttab_free_callback callback;
137 struct blk_shadow shadow[BLK_MAX_RING_SIZE];
138 struct list_head grants;
139 struct list_head indirect_pages;
140 unsigned int persistent_gnts_c;
141 unsigned long shadow_free;
142 unsigned int feature_flush;
143 unsigned int feature_discard:1;
144 unsigned int feature_secdiscard:1;
145 unsigned int discard_granularity;
146 unsigned int discard_alignment;
147 unsigned int feature_persistent:1;
148 unsigned int max_indirect_segments;
149 int is_ready;
150 };
151
152 static unsigned int nr_minors;
153 static unsigned long *minors;
154 static DEFINE_SPINLOCK(minor_lock);
155
156 #define GRANT_INVALID_REF 0
157
158 #define PARTS_PER_DISK 16
159 #define PARTS_PER_EXT_DISK 256
160
161 #define BLKIF_MAJOR(dev) ((dev)>>8)
162 #define BLKIF_MINOR(dev) ((dev) & 0xff)
163
164 #define EXT_SHIFT 28
165 #define EXTENDED (1<<EXT_SHIFT)
166 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
167 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
168 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
169 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
170 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
171 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
172
173 #define DEV_NAME "xvd" /* name in /dev */
174
175 #define SEGS_PER_INDIRECT_FRAME \
176 (PAGE_SIZE/sizeof(struct blkif_request_segment))
177 #define INDIRECT_GREFS(_segs) \
178 ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
179
180 static int blkfront_setup_indirect(struct blkfront_info *info);
181 static int blkfront_gather_backend_features(struct blkfront_info *info);
182
183 static int get_id_from_freelist(struct blkfront_info *info)
184 {
185 unsigned long free = info->shadow_free;
186 BUG_ON(free >= BLK_RING_SIZE(info));
187 info->shadow_free = info->shadow[free].req.u.rw.id;
188 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
189 return free;
190 }
191
192 static int add_id_to_freelist(struct blkfront_info *info,
193 unsigned long id)
194 {
195 if (info->shadow[id].req.u.rw.id != id)
196 return -EINVAL;
197 if (info->shadow[id].request == NULL)
198 return -EINVAL;
199 info->shadow[id].req.u.rw.id = info->shadow_free;
200 info->shadow[id].request = NULL;
201 info->shadow_free = id;
202 return 0;
203 }
204
205 static int fill_grant_buffer(struct blkfront_info *info, int num)
206 {
207 struct page *granted_page;
208 struct grant *gnt_list_entry, *n;
209 int i = 0;
210
211 while(i < num) {
212 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
213 if (!gnt_list_entry)
214 goto out_of_memory;
215
216 if (info->feature_persistent) {
217 granted_page = alloc_page(GFP_NOIO);
218 if (!granted_page) {
219 kfree(gnt_list_entry);
220 goto out_of_memory;
221 }
222 gnt_list_entry->pfn = page_to_pfn(granted_page);
223 }
224
225 gnt_list_entry->gref = GRANT_INVALID_REF;
226 list_add(&gnt_list_entry->node, &info->grants);
227 i++;
228 }
229
230 return 0;
231
232 out_of_memory:
233 list_for_each_entry_safe(gnt_list_entry, n,
234 &info->grants, node) {
235 list_del(&gnt_list_entry->node);
236 if (info->feature_persistent)
237 __free_page(pfn_to_page(gnt_list_entry->pfn));
238 kfree(gnt_list_entry);
239 i--;
240 }
241 BUG_ON(i != 0);
242 return -ENOMEM;
243 }
244
245 static struct grant *get_grant(grant_ref_t *gref_head,
246 unsigned long pfn,
247 struct blkfront_info *info)
248 {
249 struct grant *gnt_list_entry;
250 unsigned long buffer_mfn;
251
252 BUG_ON(list_empty(&info->grants));
253 gnt_list_entry = list_first_entry(&info->grants, struct grant,
254 node);
255 list_del(&gnt_list_entry->node);
256
257 if (gnt_list_entry->gref != GRANT_INVALID_REF) {
258 info->persistent_gnts_c--;
259 return gnt_list_entry;
260 }
261
262 /* Assign a gref to this page */
263 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
264 BUG_ON(gnt_list_entry->gref == -ENOSPC);
265 if (!info->feature_persistent) {
266 BUG_ON(!pfn);
267 gnt_list_entry->pfn = pfn;
268 }
269 buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
270 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
271 info->xbdev->otherend_id,
272 buffer_mfn, 0);
273 return gnt_list_entry;
274 }
275
276 static const char *op_name(int op)
277 {
278 static const char *const names[] = {
279 [BLKIF_OP_READ] = "read",
280 [BLKIF_OP_WRITE] = "write",
281 [BLKIF_OP_WRITE_BARRIER] = "barrier",
282 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
283 [BLKIF_OP_DISCARD] = "discard" };
284
285 if (op < 0 || op >= ARRAY_SIZE(names))
286 return "unknown";
287
288 if (!names[op])
289 return "reserved";
290
291 return names[op];
292 }
293 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
294 {
295 unsigned int end = minor + nr;
296 int rc;
297
298 if (end > nr_minors) {
299 unsigned long *bitmap, *old;
300
301 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
302 GFP_KERNEL);
303 if (bitmap == NULL)
304 return -ENOMEM;
305
306 spin_lock(&minor_lock);
307 if (end > nr_minors) {
308 old = minors;
309 memcpy(bitmap, minors,
310 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
311 minors = bitmap;
312 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
313 } else
314 old = bitmap;
315 spin_unlock(&minor_lock);
316 kfree(old);
317 }
318
319 spin_lock(&minor_lock);
320 if (find_next_bit(minors, end, minor) >= end) {
321 bitmap_set(minors, minor, nr);
322 rc = 0;
323 } else
324 rc = -EBUSY;
325 spin_unlock(&minor_lock);
326
327 return rc;
328 }
329
330 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
331 {
332 unsigned int end = minor + nr;
333
334 BUG_ON(end > nr_minors);
335 spin_lock(&minor_lock);
336 bitmap_clear(minors, minor, nr);
337 spin_unlock(&minor_lock);
338 }
339
340 static void blkif_restart_queue_callback(void *arg)
341 {
342 struct blkfront_info *info = (struct blkfront_info *)arg;
343 schedule_work(&info->work);
344 }
345
346 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
347 {
348 /* We don't have real geometry info, but let's at least return
349 values consistent with the size of the device */
350 sector_t nsect = get_capacity(bd->bd_disk);
351 sector_t cylinders = nsect;
352
353 hg->heads = 0xff;
354 hg->sectors = 0x3f;
355 sector_div(cylinders, hg->heads * hg->sectors);
356 hg->cylinders = cylinders;
357 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
358 hg->cylinders = 0xffff;
359 return 0;
360 }
361
362 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
363 unsigned command, unsigned long argument)
364 {
365 struct blkfront_info *info = bdev->bd_disk->private_data;
366 int i;
367
368 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
369 command, (long)argument);
370
371 switch (command) {
372 case CDROMMULTISESSION:
373 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
374 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
375 if (put_user(0, (char __user *)(argument + i)))
376 return -EFAULT;
377 return 0;
378
379 case CDROM_GET_CAPABILITY: {
380 struct gendisk *gd = info->gd;
381 if (gd->flags & GENHD_FL_CD)
382 return 0;
383 return -EINVAL;
384 }
385
386 default:
387 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
388 command);*/
389 return -EINVAL; /* same return as native Linux */
390 }
391
392 return 0;
393 }
394
395 /*
396 * Generate a Xen blkfront IO request from a blk layer request. Reads
397 * and writes are handled as expected.
398 *
399 * @req: a request struct
400 */
401 static int blkif_queue_request(struct request *req)
402 {
403 struct blkfront_info *info = req->rq_disk->private_data;
404 struct blkif_request *ring_req;
405 unsigned long id;
406 unsigned int fsect, lsect;
407 int i, ref, n;
408 struct blkif_request_segment *segments = NULL;
409
410 /*
411 * Used to store if we are able to queue the request by just using
412 * existing persistent grants, or if we have to get new grants,
413 * as there are not sufficiently many free.
414 */
415 bool new_persistent_gnts;
416 grant_ref_t gref_head;
417 struct grant *gnt_list_entry = NULL;
418 struct scatterlist *sg;
419 int nseg, max_grefs;
420
421 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
422 return 1;
423
424 max_grefs = req->nr_phys_segments;
425 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
426 /*
427 * If we are using indirect segments we need to account
428 * for the indirect grefs used in the request.
429 */
430 max_grefs += INDIRECT_GREFS(req->nr_phys_segments);
431
432 /* Check if we have enough grants to allocate a requests */
433 if (info->persistent_gnts_c < max_grefs) {
434 new_persistent_gnts = 1;
435 if (gnttab_alloc_grant_references(
436 max_grefs - info->persistent_gnts_c,
437 &gref_head) < 0) {
438 gnttab_request_free_callback(
439 &info->callback,
440 blkif_restart_queue_callback,
441 info,
442 max_grefs);
443 return 1;
444 }
445 } else
446 new_persistent_gnts = 0;
447
448 /* Fill out a communications ring structure. */
449 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
450 id = get_id_from_freelist(info);
451 info->shadow[id].request = req;
452
453 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
454 ring_req->operation = BLKIF_OP_DISCARD;
455 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
456 ring_req->u.discard.id = id;
457 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
458 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
459 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
460 else
461 ring_req->u.discard.flag = 0;
462 } else {
463 BUG_ON(info->max_indirect_segments == 0 &&
464 req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
465 BUG_ON(info->max_indirect_segments &&
466 req->nr_phys_segments > info->max_indirect_segments);
467 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
468 ring_req->u.rw.id = id;
469 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
470 /*
471 * The indirect operation can only be a BLKIF_OP_READ or
472 * BLKIF_OP_WRITE
473 */
474 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
475 ring_req->operation = BLKIF_OP_INDIRECT;
476 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
477 BLKIF_OP_WRITE : BLKIF_OP_READ;
478 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
479 ring_req->u.indirect.handle = info->handle;
480 ring_req->u.indirect.nr_segments = nseg;
481 } else {
482 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
483 ring_req->u.rw.handle = info->handle;
484 ring_req->operation = rq_data_dir(req) ?
485 BLKIF_OP_WRITE : BLKIF_OP_READ;
486 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
487 /*
488 * Ideally we can do an unordered flush-to-disk. In case the
489 * backend onlysupports barriers, use that. A barrier request
490 * a superset of FUA, so we can implement it the same
491 * way. (It's also a FLUSH+FUA, since it is
492 * guaranteed ordered WRT previous writes.)
493 */
494 switch (info->feature_flush &
495 ((REQ_FLUSH|REQ_FUA))) {
496 case REQ_FLUSH|REQ_FUA:
497 ring_req->operation =
498 BLKIF_OP_WRITE_BARRIER;
499 break;
500 case REQ_FLUSH:
501 ring_req->operation =
502 BLKIF_OP_FLUSH_DISKCACHE;
503 break;
504 default:
505 ring_req->operation = 0;
506 }
507 }
508 ring_req->u.rw.nr_segments = nseg;
509 }
510 for_each_sg(info->shadow[id].sg, sg, nseg, i) {
511 fsect = sg->offset >> 9;
512 lsect = fsect + (sg->length >> 9) - 1;
513
514 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
515 (i % SEGS_PER_INDIRECT_FRAME == 0)) {
516 unsigned long uninitialized_var(pfn);
517
518 if (segments)
519 kunmap_atomic(segments);
520
521 n = i / SEGS_PER_INDIRECT_FRAME;
522 if (!info->feature_persistent) {
523 struct page *indirect_page;
524
525 /* Fetch a pre-allocated page to use for indirect grefs */
526 BUG_ON(list_empty(&info->indirect_pages));
527 indirect_page = list_first_entry(&info->indirect_pages,
528 struct page, lru);
529 list_del(&indirect_page->lru);
530 pfn = page_to_pfn(indirect_page);
531 }
532 gnt_list_entry = get_grant(&gref_head, pfn, info);
533 info->shadow[id].indirect_grants[n] = gnt_list_entry;
534 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
535 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
536 }
537
538 gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
539 ref = gnt_list_entry->gref;
540
541 info->shadow[id].grants_used[i] = gnt_list_entry;
542
543 if (rq_data_dir(req) && info->feature_persistent) {
544 char *bvec_data;
545 void *shared_data;
546
547 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
548
549 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
550 bvec_data = kmap_atomic(sg_page(sg));
551
552 /*
553 * this does not wipe data stored outside the
554 * range sg->offset..sg->offset+sg->length.
555 * Therefore, blkback *could* see data from
556 * previous requests. This is OK as long as
557 * persistent grants are shared with just one
558 * domain. It may need refactoring if this
559 * changes
560 */
561 memcpy(shared_data + sg->offset,
562 bvec_data + sg->offset,
563 sg->length);
564
565 kunmap_atomic(bvec_data);
566 kunmap_atomic(shared_data);
567 }
568 if (ring_req->operation != BLKIF_OP_INDIRECT) {
569 ring_req->u.rw.seg[i] =
570 (struct blkif_request_segment) {
571 .gref = ref,
572 .first_sect = fsect,
573 .last_sect = lsect };
574 } else {
575 n = i % SEGS_PER_INDIRECT_FRAME;
576 segments[n] =
577 (struct blkif_request_segment) {
578 .gref = ref,
579 .first_sect = fsect,
580 .last_sect = lsect };
581 }
582 }
583 if (segments)
584 kunmap_atomic(segments);
585 }
586
587 info->ring.req_prod_pvt++;
588
589 /* Keep a private copy so we can reissue requests when recovering. */
590 info->shadow[id].req = *ring_req;
591
592 if (new_persistent_gnts)
593 gnttab_free_grant_references(gref_head);
594
595 return 0;
596 }
597
598
599 static inline void flush_requests(struct blkfront_info *info)
600 {
601 int notify;
602
603 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
604
605 if (notify)
606 notify_remote_via_irq(info->irq);
607 }
608
609 static inline bool blkif_request_flush_invalid(struct request *req,
610 struct blkfront_info *info)
611 {
612 return ((req->cmd_type != REQ_TYPE_FS) ||
613 ((req->cmd_flags & REQ_FLUSH) &&
614 !(info->feature_flush & REQ_FLUSH)) ||
615 ((req->cmd_flags & REQ_FUA) &&
616 !(info->feature_flush & REQ_FUA)));
617 }
618
619 /*
620 * do_blkif_request
621 * read a block; request is in a request queue
622 */
623 static void do_blkif_request(struct request_queue *rq)
624 {
625 struct blkfront_info *info = NULL;
626 struct request *req;
627 int queued;
628
629 pr_debug("Entered do_blkif_request\n");
630
631 queued = 0;
632
633 while ((req = blk_peek_request(rq)) != NULL) {
634 info = req->rq_disk->private_data;
635
636 if (RING_FULL(&info->ring))
637 goto wait;
638
639 blk_start_request(req);
640
641 if (blkif_request_flush_invalid(req, info)) {
642 __blk_end_request_all(req, -EOPNOTSUPP);
643 continue;
644 }
645
646 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
647 "(%u/%u) [%s]\n",
648 req, req->cmd, (unsigned long)blk_rq_pos(req),
649 blk_rq_cur_sectors(req), blk_rq_sectors(req),
650 rq_data_dir(req) ? "write" : "read");
651
652 if (blkif_queue_request(req)) {
653 blk_requeue_request(rq, req);
654 wait:
655 /* Avoid pointless unplugs. */
656 blk_stop_queue(rq);
657 break;
658 }
659
660 queued++;
661 }
662
663 if (queued != 0)
664 flush_requests(info);
665 }
666
667 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
668 unsigned int physical_sector_size,
669 unsigned int segments)
670 {
671 struct request_queue *rq;
672 struct blkfront_info *info = gd->private_data;
673
674 rq = blk_init_queue(do_blkif_request, &info->io_lock);
675 if (rq == NULL)
676 return -1;
677
678 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
679
680 if (info->feature_discard) {
681 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
682 blk_queue_max_discard_sectors(rq, get_capacity(gd));
683 rq->limits.discard_granularity = info->discard_granularity;
684 rq->limits.discard_alignment = info->discard_alignment;
685 if (info->feature_secdiscard)
686 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
687 }
688
689 /* Hard sector size and max sectors impersonate the equiv. hardware. */
690 blk_queue_logical_block_size(rq, sector_size);
691 blk_queue_physical_block_size(rq, physical_sector_size);
692 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512);
693
694 /* Each segment in a request is up to an aligned page in size. */
695 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
696 blk_queue_max_segment_size(rq, PAGE_SIZE);
697
698 /* Ensure a merged request will fit in a single I/O ring slot. */
699 blk_queue_max_segments(rq, segments);
700
701 /* Make sure buffer addresses are sector-aligned. */
702 blk_queue_dma_alignment(rq, 511);
703
704 /* Make sure we don't use bounce buffers. */
705 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
706
707 gd->queue = rq;
708
709 return 0;
710 }
711
712 static const char *flush_info(unsigned int feature_flush)
713 {
714 switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) {
715 case REQ_FLUSH|REQ_FUA:
716 return "barrier: enabled;";
717 case REQ_FLUSH:
718 return "flush diskcache: enabled;";
719 default:
720 return "barrier or flush: disabled;";
721 }
722 }
723
724 static void xlvbd_flush(struct blkfront_info *info)
725 {
726 blk_queue_flush(info->rq, info->feature_flush);
727 pr_info("blkfront: %s: %s %s %s %s %s\n",
728 info->gd->disk_name, flush_info(info->feature_flush),
729 "persistent grants:", info->feature_persistent ?
730 "enabled;" : "disabled;", "indirect descriptors:",
731 info->max_indirect_segments ? "enabled;" : "disabled;");
732 }
733
734 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
735 {
736 int major;
737 major = BLKIF_MAJOR(vdevice);
738 *minor = BLKIF_MINOR(vdevice);
739 switch (major) {
740 case XEN_IDE0_MAJOR:
741 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
742 *minor = ((*minor / 64) * PARTS_PER_DISK) +
743 EMULATED_HD_DISK_MINOR_OFFSET;
744 break;
745 case XEN_IDE1_MAJOR:
746 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
747 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
748 EMULATED_HD_DISK_MINOR_OFFSET;
749 break;
750 case XEN_SCSI_DISK0_MAJOR:
751 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
752 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
753 break;
754 case XEN_SCSI_DISK1_MAJOR:
755 case XEN_SCSI_DISK2_MAJOR:
756 case XEN_SCSI_DISK3_MAJOR:
757 case XEN_SCSI_DISK4_MAJOR:
758 case XEN_SCSI_DISK5_MAJOR:
759 case XEN_SCSI_DISK6_MAJOR:
760 case XEN_SCSI_DISK7_MAJOR:
761 *offset = (*minor / PARTS_PER_DISK) +
762 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
763 EMULATED_SD_DISK_NAME_OFFSET;
764 *minor = *minor +
765 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
766 EMULATED_SD_DISK_MINOR_OFFSET;
767 break;
768 case XEN_SCSI_DISK8_MAJOR:
769 case XEN_SCSI_DISK9_MAJOR:
770 case XEN_SCSI_DISK10_MAJOR:
771 case XEN_SCSI_DISK11_MAJOR:
772 case XEN_SCSI_DISK12_MAJOR:
773 case XEN_SCSI_DISK13_MAJOR:
774 case XEN_SCSI_DISK14_MAJOR:
775 case XEN_SCSI_DISK15_MAJOR:
776 *offset = (*minor / PARTS_PER_DISK) +
777 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
778 EMULATED_SD_DISK_NAME_OFFSET;
779 *minor = *minor +
780 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
781 EMULATED_SD_DISK_MINOR_OFFSET;
782 break;
783 case XENVBD_MAJOR:
784 *offset = *minor / PARTS_PER_DISK;
785 break;
786 default:
787 printk(KERN_WARNING "blkfront: your disk configuration is "
788 "incorrect, please use an xvd device instead\n");
789 return -ENODEV;
790 }
791 return 0;
792 }
793
794 static char *encode_disk_name(char *ptr, unsigned int n)
795 {
796 if (n >= 26)
797 ptr = encode_disk_name(ptr, n / 26 - 1);
798 *ptr = 'a' + n % 26;
799 return ptr + 1;
800 }
801
802 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
803 struct blkfront_info *info,
804 u16 vdisk_info, u16 sector_size,
805 unsigned int physical_sector_size)
806 {
807 struct gendisk *gd;
808 int nr_minors = 1;
809 int err;
810 unsigned int offset;
811 int minor;
812 int nr_parts;
813 char *ptr;
814
815 BUG_ON(info->gd != NULL);
816 BUG_ON(info->rq != NULL);
817
818 if ((info->vdevice>>EXT_SHIFT) > 1) {
819 /* this is above the extended range; something is wrong */
820 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
821 return -ENODEV;
822 }
823
824 if (!VDEV_IS_EXTENDED(info->vdevice)) {
825 err = xen_translate_vdev(info->vdevice, &minor, &offset);
826 if (err)
827 return err;
828 nr_parts = PARTS_PER_DISK;
829 } else {
830 minor = BLKIF_MINOR_EXT(info->vdevice);
831 nr_parts = PARTS_PER_EXT_DISK;
832 offset = minor / nr_parts;
833 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
834 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
835 "emulated IDE disks,\n\t choose an xvd device name"
836 "from xvde on\n", info->vdevice);
837 }
838 if (minor >> MINORBITS) {
839 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
840 info->vdevice, minor);
841 return -ENODEV;
842 }
843
844 if ((minor % nr_parts) == 0)
845 nr_minors = nr_parts;
846
847 err = xlbd_reserve_minors(minor, nr_minors);
848 if (err)
849 goto out;
850 err = -ENODEV;
851
852 gd = alloc_disk(nr_minors);
853 if (gd == NULL)
854 goto release;
855
856 strcpy(gd->disk_name, DEV_NAME);
857 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
858 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
859 if (nr_minors > 1)
860 *ptr = 0;
861 else
862 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
863 "%d", minor & (nr_parts - 1));
864
865 gd->major = XENVBD_MAJOR;
866 gd->first_minor = minor;
867 gd->fops = &xlvbd_block_fops;
868 gd->private_data = info;
869 gd->driverfs_dev = &(info->xbdev->dev);
870 set_capacity(gd, capacity);
871
872 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
873 info->max_indirect_segments ? :
874 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
875 del_gendisk(gd);
876 goto release;
877 }
878
879 info->rq = gd->queue;
880 info->gd = gd;
881
882 xlvbd_flush(info);
883
884 if (vdisk_info & VDISK_READONLY)
885 set_disk_ro(gd, 1);
886
887 if (vdisk_info & VDISK_REMOVABLE)
888 gd->flags |= GENHD_FL_REMOVABLE;
889
890 if (vdisk_info & VDISK_CDROM)
891 gd->flags |= GENHD_FL_CD;
892
893 return 0;
894
895 release:
896 xlbd_release_minors(minor, nr_minors);
897 out:
898 return err;
899 }
900
901 static void xlvbd_release_gendisk(struct blkfront_info *info)
902 {
903 unsigned int minor, nr_minors;
904 unsigned long flags;
905
906 if (info->rq == NULL)
907 return;
908
909 spin_lock_irqsave(&info->io_lock, flags);
910
911 /* No more blkif_request(). */
912 blk_stop_queue(info->rq);
913
914 /* No more gnttab callback work. */
915 gnttab_cancel_free_callback(&info->callback);
916 spin_unlock_irqrestore(&info->io_lock, flags);
917
918 /* Flush gnttab callback work. Must be done with no locks held. */
919 flush_work(&info->work);
920
921 del_gendisk(info->gd);
922
923 minor = info->gd->first_minor;
924 nr_minors = info->gd->minors;
925 xlbd_release_minors(minor, nr_minors);
926
927 blk_cleanup_queue(info->rq);
928 info->rq = NULL;
929
930 put_disk(info->gd);
931 info->gd = NULL;
932 }
933
934 static void kick_pending_request_queues(struct blkfront_info *info)
935 {
936 if (!RING_FULL(&info->ring)) {
937 /* Re-enable calldowns. */
938 blk_start_queue(info->rq);
939 /* Kick things off immediately. */
940 do_blkif_request(info->rq);
941 }
942 }
943
944 static void blkif_restart_queue(struct work_struct *work)
945 {
946 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
947
948 spin_lock_irq(&info->io_lock);
949 if (info->connected == BLKIF_STATE_CONNECTED)
950 kick_pending_request_queues(info);
951 spin_unlock_irq(&info->io_lock);
952 }
953
954 static void blkif_free(struct blkfront_info *info, int suspend)
955 {
956 struct grant *persistent_gnt;
957 struct grant *n;
958 int i, j, segs;
959
960 /* Prevent new requests being issued until we fix things up. */
961 spin_lock_irq(&info->io_lock);
962 info->connected = suspend ?
963 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
964 /* No more blkif_request(). */
965 if (info->rq)
966 blk_stop_queue(info->rq);
967
968 /* Remove all persistent grants */
969 if (!list_empty(&info->grants)) {
970 list_for_each_entry_safe(persistent_gnt, n,
971 &info->grants, node) {
972 list_del(&persistent_gnt->node);
973 if (persistent_gnt->gref != GRANT_INVALID_REF) {
974 gnttab_end_foreign_access(persistent_gnt->gref,
975 0, 0UL);
976 info->persistent_gnts_c--;
977 }
978 if (info->feature_persistent)
979 __free_page(pfn_to_page(persistent_gnt->pfn));
980 kfree(persistent_gnt);
981 }
982 }
983 BUG_ON(info->persistent_gnts_c != 0);
984
985 /*
986 * Remove indirect pages, this only happens when using indirect
987 * descriptors but not persistent grants
988 */
989 if (!list_empty(&info->indirect_pages)) {
990 struct page *indirect_page, *n;
991
992 BUG_ON(info->feature_persistent);
993 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
994 list_del(&indirect_page->lru);
995 __free_page(indirect_page);
996 }
997 }
998
999 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1000 /*
1001 * Clear persistent grants present in requests already
1002 * on the shared ring
1003 */
1004 if (!info->shadow[i].request)
1005 goto free_shadow;
1006
1007 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1008 info->shadow[i].req.u.indirect.nr_segments :
1009 info->shadow[i].req.u.rw.nr_segments;
1010 for (j = 0; j < segs; j++) {
1011 persistent_gnt = info->shadow[i].grants_used[j];
1012 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1013 if (info->feature_persistent)
1014 __free_page(pfn_to_page(persistent_gnt->pfn));
1015 kfree(persistent_gnt);
1016 }
1017
1018 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1019 /*
1020 * If this is not an indirect operation don't try to
1021 * free indirect segments
1022 */
1023 goto free_shadow;
1024
1025 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1026 persistent_gnt = info->shadow[i].indirect_grants[j];
1027 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1028 __free_page(pfn_to_page(persistent_gnt->pfn));
1029 kfree(persistent_gnt);
1030 }
1031
1032 free_shadow:
1033 kfree(info->shadow[i].grants_used);
1034 info->shadow[i].grants_used = NULL;
1035 kfree(info->shadow[i].indirect_grants);
1036 info->shadow[i].indirect_grants = NULL;
1037 kfree(info->shadow[i].sg);
1038 info->shadow[i].sg = NULL;
1039 }
1040
1041 /* No more gnttab callback work. */
1042 gnttab_cancel_free_callback(&info->callback);
1043 spin_unlock_irq(&info->io_lock);
1044
1045 /* Flush gnttab callback work. Must be done with no locks held. */
1046 flush_work(&info->work);
1047
1048 /* Free resources associated with old device channel. */
1049 for (i = 0; i < info->nr_ring_pages; i++) {
1050 if (info->ring_ref[i] != GRANT_INVALID_REF) {
1051 gnttab_end_foreign_access(info->ring_ref[i], 0, 0);
1052 info->ring_ref[i] = GRANT_INVALID_REF;
1053 }
1054 }
1055 free_pages((unsigned long)info->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE));
1056 info->ring.sring = NULL;
1057
1058 if (info->irq)
1059 unbind_from_irqhandler(info->irq, info);
1060 info->evtchn = info->irq = 0;
1061
1062 }
1063
1064 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
1065 struct blkif_response *bret)
1066 {
1067 int i = 0;
1068 struct scatterlist *sg;
1069 char *bvec_data;
1070 void *shared_data;
1071 int nseg;
1072
1073 nseg = s->req.operation == BLKIF_OP_INDIRECT ?
1074 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1075
1076 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1077 for_each_sg(s->sg, sg, nseg, i) {
1078 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1079 shared_data = kmap_atomic(
1080 pfn_to_page(s->grants_used[i]->pfn));
1081 bvec_data = kmap_atomic(sg_page(sg));
1082 memcpy(bvec_data + sg->offset,
1083 shared_data + sg->offset,
1084 sg->length);
1085 kunmap_atomic(bvec_data);
1086 kunmap_atomic(shared_data);
1087 }
1088 }
1089 /* Add the persistent grant into the list of free grants */
1090 for (i = 0; i < nseg; i++) {
1091 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1092 /*
1093 * If the grant is still mapped by the backend (the
1094 * backend has chosen to make this grant persistent)
1095 * we add it at the head of the list, so it will be
1096 * reused first.
1097 */
1098 if (!info->feature_persistent)
1099 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1100 s->grants_used[i]->gref);
1101 list_add(&s->grants_used[i]->node, &info->grants);
1102 info->persistent_gnts_c++;
1103 } else {
1104 /*
1105 * If the grant is not mapped by the backend we end the
1106 * foreign access and add it to the tail of the list,
1107 * so it will not be picked again unless we run out of
1108 * persistent grants.
1109 */
1110 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1111 s->grants_used[i]->gref = GRANT_INVALID_REF;
1112 list_add_tail(&s->grants_used[i]->node, &info->grants);
1113 }
1114 }
1115 if (s->req.operation == BLKIF_OP_INDIRECT) {
1116 for (i = 0; i < INDIRECT_GREFS(nseg); i++) {
1117 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1118 if (!info->feature_persistent)
1119 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1120 s->indirect_grants[i]->gref);
1121 list_add(&s->indirect_grants[i]->node, &info->grants);
1122 info->persistent_gnts_c++;
1123 } else {
1124 struct page *indirect_page;
1125
1126 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1127 /*
1128 * Add the used indirect page back to the list of
1129 * available pages for indirect grefs.
1130 */
1131 if (!info->feature_persistent) {
1132 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
1133 list_add(&indirect_page->lru, &info->indirect_pages);
1134 }
1135 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1136 list_add_tail(&s->indirect_grants[i]->node, &info->grants);
1137 }
1138 }
1139 }
1140 }
1141
1142 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1143 {
1144 struct request *req;
1145 struct blkif_response *bret;
1146 RING_IDX i, rp;
1147 unsigned long flags;
1148 struct blkfront_info *info = (struct blkfront_info *)dev_id;
1149 int error;
1150
1151 spin_lock_irqsave(&info->io_lock, flags);
1152
1153 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1154 spin_unlock_irqrestore(&info->io_lock, flags);
1155 return IRQ_HANDLED;
1156 }
1157
1158 again:
1159 rp = info->ring.sring->rsp_prod;
1160 rmb(); /* Ensure we see queued responses up to 'rp'. */
1161
1162 for (i = info->ring.rsp_cons; i != rp; i++) {
1163 unsigned long id;
1164
1165 bret = RING_GET_RESPONSE(&info->ring, i);
1166 id = bret->id;
1167 /*
1168 * The backend has messed up and given us an id that we would
1169 * never have given to it (we stamp it up to BLK_RING_SIZE -
1170 * look in get_id_from_freelist.
1171 */
1172 if (id >= BLK_RING_SIZE(info)) {
1173 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1174 info->gd->disk_name, op_name(bret->operation), id);
1175 /* We can't safely get the 'struct request' as
1176 * the id is busted. */
1177 continue;
1178 }
1179 req = info->shadow[id].request;
1180
1181 if (bret->operation != BLKIF_OP_DISCARD)
1182 blkif_completion(&info->shadow[id], info, bret);
1183
1184 if (add_id_to_freelist(info, id)) {
1185 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1186 info->gd->disk_name, op_name(bret->operation), id);
1187 continue;
1188 }
1189
1190 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1191 switch (bret->operation) {
1192 case BLKIF_OP_DISCARD:
1193 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1194 struct request_queue *rq = info->rq;
1195 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1196 info->gd->disk_name, op_name(bret->operation));
1197 error = -EOPNOTSUPP;
1198 info->feature_discard = 0;
1199 info->feature_secdiscard = 0;
1200 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1201 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1202 }
1203 __blk_end_request_all(req, error);
1204 break;
1205 case BLKIF_OP_FLUSH_DISKCACHE:
1206 case BLKIF_OP_WRITE_BARRIER:
1207 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1208 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1209 info->gd->disk_name, op_name(bret->operation));
1210 error = -EOPNOTSUPP;
1211 }
1212 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1213 info->shadow[id].req.u.rw.nr_segments == 0)) {
1214 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1215 info->gd->disk_name, op_name(bret->operation));
1216 error = -EOPNOTSUPP;
1217 }
1218 if (unlikely(error)) {
1219 if (error == -EOPNOTSUPP)
1220 error = 0;
1221 info->feature_flush = 0;
1222 xlvbd_flush(info);
1223 }
1224 /* fall through */
1225 case BLKIF_OP_READ:
1226 case BLKIF_OP_WRITE:
1227 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1228 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1229 "request: %x\n", bret->status);
1230
1231 __blk_end_request_all(req, error);
1232 break;
1233 default:
1234 BUG();
1235 }
1236 }
1237
1238 info->ring.rsp_cons = i;
1239
1240 if (i != info->ring.req_prod_pvt) {
1241 int more_to_do;
1242 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
1243 if (more_to_do)
1244 goto again;
1245 } else
1246 info->ring.sring->rsp_event = i + 1;
1247
1248 kick_pending_request_queues(info);
1249
1250 spin_unlock_irqrestore(&info->io_lock, flags);
1251
1252 return IRQ_HANDLED;
1253 }
1254
1255
1256 static int setup_blkring(struct xenbus_device *dev,
1257 struct blkfront_info *info)
1258 {
1259 struct blkif_sring *sring;
1260 int err, i;
1261 unsigned long ring_size = info->nr_ring_pages * PAGE_SIZE;
1262 grant_ref_t gref[XENBUS_MAX_RING_PAGES];
1263
1264 for (i = 0; i < info->nr_ring_pages; i++)
1265 info->ring_ref[i] = GRANT_INVALID_REF;
1266
1267 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1268 get_order(ring_size));
1269 if (!sring) {
1270 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1271 return -ENOMEM;
1272 }
1273 SHARED_RING_INIT(sring);
1274 FRONT_RING_INIT(&info->ring, sring, ring_size);
1275
1276 err = xenbus_grant_ring(dev, info->ring.sring, info->nr_ring_pages, gref);
1277 if (err < 0) {
1278 free_pages((unsigned long)sring, get_order(ring_size));
1279 info->ring.sring = NULL;
1280 goto fail;
1281 }
1282 for (i = 0; i < info->nr_ring_pages; i++)
1283 info->ring_ref[i] = gref[i];
1284
1285 err = xenbus_alloc_evtchn(dev, &info->evtchn);
1286 if (err)
1287 goto fail;
1288
1289 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
1290 "blkif", info);
1291 if (err <= 0) {
1292 xenbus_dev_fatal(dev, err,
1293 "bind_evtchn_to_irqhandler failed");
1294 goto fail;
1295 }
1296 info->irq = err;
1297
1298 return 0;
1299 fail:
1300 blkif_free(info, 0);
1301 return err;
1302 }
1303
1304
1305 /* Common code used when first setting up, and when resuming. */
1306 static int talk_to_blkback(struct xenbus_device *dev,
1307 struct blkfront_info *info)
1308 {
1309 const char *message = NULL;
1310 struct xenbus_transaction xbt;
1311 int err, i;
1312 unsigned int max_page_order = 0;
1313 unsigned int ring_page_order = 0;
1314
1315 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1316 "max-ring-page-order", "%u", &max_page_order);
1317 if (err != 1)
1318 info->nr_ring_pages = 1;
1319 else {
1320 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1321 info->nr_ring_pages = 1 << ring_page_order;
1322 }
1323
1324 /* Create shared ring, alloc event channel. */
1325 err = setup_blkring(dev, info);
1326 if (err)
1327 goto out;
1328
1329 again:
1330 err = xenbus_transaction_start(&xbt);
1331 if (err) {
1332 xenbus_dev_fatal(dev, err, "starting transaction");
1333 goto destroy_blkring;
1334 }
1335
1336 if (info->nr_ring_pages == 1) {
1337 err = xenbus_printf(xbt, dev->nodename,
1338 "ring-ref", "%u", info->ring_ref[0]);
1339 if (err) {
1340 message = "writing ring-ref";
1341 goto abort_transaction;
1342 }
1343 } else {
1344 err = xenbus_printf(xbt, dev->nodename,
1345 "ring-page-order", "%u", ring_page_order);
1346 if (err) {
1347 message = "writing ring-page-order";
1348 goto abort_transaction;
1349 }
1350
1351 for (i = 0; i < info->nr_ring_pages; i++) {
1352 char ring_ref_name[RINGREF_NAME_LEN];
1353
1354 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1355 err = xenbus_printf(xbt, dev->nodename, ring_ref_name,
1356 "%u", info->ring_ref[i]);
1357 if (err) {
1358 message = "writing ring-ref";
1359 goto abort_transaction;
1360 }
1361 }
1362 }
1363 err = xenbus_printf(xbt, dev->nodename,
1364 "event-channel", "%u", info->evtchn);
1365 if (err) {
1366 message = "writing event-channel";
1367 goto abort_transaction;
1368 }
1369 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1370 XEN_IO_PROTO_ABI_NATIVE);
1371 if (err) {
1372 message = "writing protocol";
1373 goto abort_transaction;
1374 }
1375 err = xenbus_printf(xbt, dev->nodename,
1376 "feature-persistent", "%u", 1);
1377 if (err)
1378 dev_warn(&dev->dev,
1379 "writing persistent grants feature to xenbus");
1380
1381 err = xenbus_transaction_end(xbt, 0);
1382 if (err) {
1383 if (err == -EAGAIN)
1384 goto again;
1385 xenbus_dev_fatal(dev, err, "completing transaction");
1386 goto destroy_blkring;
1387 }
1388
1389 for (i = 0; i < BLK_RING_SIZE(info); i++)
1390 info->shadow[i].req.u.rw.id = i+1;
1391 info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1392 xenbus_switch_state(dev, XenbusStateInitialised);
1393
1394 return 0;
1395
1396 abort_transaction:
1397 xenbus_transaction_end(xbt, 1);
1398 if (message)
1399 xenbus_dev_fatal(dev, err, "%s", message);
1400 destroy_blkring:
1401 blkif_free(info, 0);
1402 out:
1403 return err;
1404 }
1405
1406 /**
1407 * Entry point to this code when a new device is created. Allocate the basic
1408 * structures and the ring buffer for communication with the backend, and
1409 * inform the backend of the appropriate details for those. Switch to
1410 * Initialised state.
1411 */
1412 static int blkfront_probe(struct xenbus_device *dev,
1413 const struct xenbus_device_id *id)
1414 {
1415 int err, vdevice;
1416 struct blkfront_info *info;
1417
1418 /* FIXME: Use dynamic device id if this is not set. */
1419 err = xenbus_scanf(XBT_NIL, dev->nodename,
1420 "virtual-device", "%i", &vdevice);
1421 if (err != 1) {
1422 /* go looking in the extended area instead */
1423 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1424 "%i", &vdevice);
1425 if (err != 1) {
1426 xenbus_dev_fatal(dev, err, "reading virtual-device");
1427 return err;
1428 }
1429 }
1430
1431 if (xen_hvm_domain()) {
1432 char *type;
1433 int len;
1434 /* no unplug has been done: do not hook devices != xen vbds */
1435 if (xen_has_pv_and_legacy_disk_devices()) {
1436 int major;
1437
1438 if (!VDEV_IS_EXTENDED(vdevice))
1439 major = BLKIF_MAJOR(vdevice);
1440 else
1441 major = XENVBD_MAJOR;
1442
1443 if (major != XENVBD_MAJOR) {
1444 printk(KERN_INFO
1445 "%s: HVM does not support vbd %d as xen block device\n",
1446 __func__, vdevice);
1447 return -ENODEV;
1448 }
1449 }
1450 /* do not create a PV cdrom device if we are an HVM guest */
1451 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1452 if (IS_ERR(type))
1453 return -ENODEV;
1454 if (strncmp(type, "cdrom", 5) == 0) {
1455 kfree(type);
1456 return -ENODEV;
1457 }
1458 kfree(type);
1459 }
1460 info = kzalloc(sizeof(*info), GFP_KERNEL);
1461 if (!info) {
1462 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1463 return -ENOMEM;
1464 }
1465
1466 mutex_init(&info->mutex);
1467 spin_lock_init(&info->io_lock);
1468 info->xbdev = dev;
1469 info->vdevice = vdevice;
1470 INIT_LIST_HEAD(&info->grants);
1471 INIT_LIST_HEAD(&info->indirect_pages);
1472 info->persistent_gnts_c = 0;
1473 info->connected = BLKIF_STATE_DISCONNECTED;
1474 INIT_WORK(&info->work, blkif_restart_queue);
1475
1476 /* Front end dir is a number, which is used as the id. */
1477 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1478 dev_set_drvdata(&dev->dev, info);
1479
1480 return 0;
1481 }
1482
1483 static void split_bio_end(struct bio *bio)
1484 {
1485 struct split_bio *split_bio = bio->bi_private;
1486
1487 if (atomic_dec_and_test(&split_bio->pending)) {
1488 split_bio->bio->bi_phys_segments = 0;
1489 split_bio->bio->bi_error = bio->bi_error;
1490 bio_endio(split_bio->bio);
1491 kfree(split_bio);
1492 }
1493 bio_put(bio);
1494 }
1495
1496 static int blkif_recover(struct blkfront_info *info)
1497 {
1498 int i;
1499 struct request *req, *n;
1500 struct blk_shadow *copy;
1501 int rc;
1502 struct bio *bio, *cloned_bio;
1503 struct bio_list bio_list, merge_bio;
1504 unsigned int segs, offset;
1505 int pending, size;
1506 struct split_bio *split_bio;
1507 struct list_head requests;
1508
1509 /* Stage 1: Make a safe copy of the shadow state. */
1510 copy = kmemdup(info->shadow, sizeof(info->shadow),
1511 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1512 if (!copy)
1513 return -ENOMEM;
1514
1515 /* Stage 2: Set up free list. */
1516 memset(&info->shadow, 0, sizeof(info->shadow));
1517 for (i = 0; i < BLK_RING_SIZE(info); i++)
1518 info->shadow[i].req.u.rw.id = i+1;
1519 info->shadow_free = info->ring.req_prod_pvt;
1520 info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1521
1522 rc = blkfront_gather_backend_features(info);
1523 if (rc) {
1524 kfree(copy);
1525 return rc;
1526 }
1527
1528 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
1529 blk_queue_max_segments(info->rq, segs);
1530 bio_list_init(&bio_list);
1531 INIT_LIST_HEAD(&requests);
1532 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1533 /* Not in use? */
1534 if (!copy[i].request)
1535 continue;
1536
1537 /*
1538 * Get the bios in the request so we can re-queue them.
1539 */
1540 if (copy[i].request->cmd_flags &
1541 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1542 /*
1543 * Flush operations don't contain bios, so
1544 * we need to requeue the whole request
1545 */
1546 list_add(&copy[i].request->queuelist, &requests);
1547 continue;
1548 }
1549 merge_bio.head = copy[i].request->bio;
1550 merge_bio.tail = copy[i].request->biotail;
1551 bio_list_merge(&bio_list, &merge_bio);
1552 copy[i].request->bio = NULL;
1553 blk_end_request_all(copy[i].request, 0);
1554 }
1555
1556 kfree(copy);
1557
1558 /*
1559 * Empty the queue, this is important because we might have
1560 * requests in the queue with more segments than what we
1561 * can handle now.
1562 */
1563 spin_lock_irq(&info->io_lock);
1564 while ((req = blk_fetch_request(info->rq)) != NULL) {
1565 if (req->cmd_flags &
1566 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1567 list_add(&req->queuelist, &requests);
1568 continue;
1569 }
1570 merge_bio.head = req->bio;
1571 merge_bio.tail = req->biotail;
1572 bio_list_merge(&bio_list, &merge_bio);
1573 req->bio = NULL;
1574 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA))
1575 pr_alert("diskcache flush request found!\n");
1576 __blk_end_request_all(req, 0);
1577 }
1578 spin_unlock_irq(&info->io_lock);
1579
1580 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1581
1582 spin_lock_irq(&info->io_lock);
1583
1584 /* Now safe for us to use the shared ring */
1585 info->connected = BLKIF_STATE_CONNECTED;
1586
1587 /* Kick any other new requests queued since we resumed */
1588 kick_pending_request_queues(info);
1589
1590 list_for_each_entry_safe(req, n, &requests, queuelist) {
1591 /* Requeue pending requests (flush or discard) */
1592 list_del_init(&req->queuelist);
1593 BUG_ON(req->nr_phys_segments > segs);
1594 blk_requeue_request(info->rq, req);
1595 }
1596 spin_unlock_irq(&info->io_lock);
1597
1598 while ((bio = bio_list_pop(&bio_list)) != NULL) {
1599 /* Traverse the list of pending bios and re-queue them */
1600 if (bio_segments(bio) > segs) {
1601 /*
1602 * This bio has more segments than what we can
1603 * handle, we have to split it.
1604 */
1605 pending = (bio_segments(bio) + segs - 1) / segs;
1606 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
1607 BUG_ON(split_bio == NULL);
1608 atomic_set(&split_bio->pending, pending);
1609 split_bio->bio = bio;
1610 for (i = 0; i < pending; i++) {
1611 offset = (i * segs * PAGE_SIZE) >> 9;
1612 size = min((unsigned int)(segs * PAGE_SIZE) >> 9,
1613 (unsigned int)bio_sectors(bio) - offset);
1614 cloned_bio = bio_clone(bio, GFP_NOIO);
1615 BUG_ON(cloned_bio == NULL);
1616 bio_trim(cloned_bio, offset, size);
1617 cloned_bio->bi_private = split_bio;
1618 cloned_bio->bi_end_io = split_bio_end;
1619 submit_bio(cloned_bio->bi_rw, cloned_bio);
1620 }
1621 /*
1622 * Now we have to wait for all those smaller bios to
1623 * end, so we can also end the "parent" bio.
1624 */
1625 continue;
1626 }
1627 /* We don't need to split this bio */
1628 submit_bio(bio->bi_rw, bio);
1629 }
1630
1631 return 0;
1632 }
1633
1634 /**
1635 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1636 * driver restart. We tear down our blkif structure and recreate it, but
1637 * leave the device-layer structures intact so that this is transparent to the
1638 * rest of the kernel.
1639 */
1640 static int blkfront_resume(struct xenbus_device *dev)
1641 {
1642 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1643 int err;
1644
1645 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1646
1647 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1648
1649 err = talk_to_blkback(dev, info);
1650
1651 /*
1652 * We have to wait for the backend to switch to
1653 * connected state, since we want to read which
1654 * features it supports.
1655 */
1656
1657 return err;
1658 }
1659
1660 static void
1661 blkfront_closing(struct blkfront_info *info)
1662 {
1663 struct xenbus_device *xbdev = info->xbdev;
1664 struct block_device *bdev = NULL;
1665
1666 mutex_lock(&info->mutex);
1667
1668 if (xbdev->state == XenbusStateClosing) {
1669 mutex_unlock(&info->mutex);
1670 return;
1671 }
1672
1673 if (info->gd)
1674 bdev = bdget_disk(info->gd, 0);
1675
1676 mutex_unlock(&info->mutex);
1677
1678 if (!bdev) {
1679 xenbus_frontend_closed(xbdev);
1680 return;
1681 }
1682
1683 mutex_lock(&bdev->bd_mutex);
1684
1685 if (bdev->bd_openers) {
1686 xenbus_dev_error(xbdev, -EBUSY,
1687 "Device in use; refusing to close");
1688 xenbus_switch_state(xbdev, XenbusStateClosing);
1689 } else {
1690 xlvbd_release_gendisk(info);
1691 xenbus_frontend_closed(xbdev);
1692 }
1693
1694 mutex_unlock(&bdev->bd_mutex);
1695 bdput(bdev);
1696 }
1697
1698 static void blkfront_setup_discard(struct blkfront_info *info)
1699 {
1700 int err;
1701 unsigned int discard_granularity;
1702 unsigned int discard_alignment;
1703 unsigned int discard_secure;
1704
1705 info->feature_discard = 1;
1706 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1707 "discard-granularity", "%u", &discard_granularity,
1708 "discard-alignment", "%u", &discard_alignment,
1709 NULL);
1710 if (!err) {
1711 info->discard_granularity = discard_granularity;
1712 info->discard_alignment = discard_alignment;
1713 }
1714 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1715 "discard-secure", "%d", &discard_secure,
1716 NULL);
1717 if (!err)
1718 info->feature_secdiscard = !!discard_secure;
1719 }
1720
1721 static int blkfront_setup_indirect(struct blkfront_info *info)
1722 {
1723 unsigned int segs;
1724 int err, i;
1725
1726 if (info->max_indirect_segments == 0)
1727 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
1728 else
1729 segs = info->max_indirect_segments;
1730
1731 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE(info));
1732 if (err)
1733 goto out_of_memory;
1734
1735 if (!info->feature_persistent && info->max_indirect_segments) {
1736 /*
1737 * We are using indirect descriptors but not persistent
1738 * grants, we need to allocate a set of pages that can be
1739 * used for mapping indirect grefs
1740 */
1741 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE(info);
1742
1743 BUG_ON(!list_empty(&info->indirect_pages));
1744 for (i = 0; i < num; i++) {
1745 struct page *indirect_page = alloc_page(GFP_NOIO);
1746 if (!indirect_page)
1747 goto out_of_memory;
1748 list_add(&indirect_page->lru, &info->indirect_pages);
1749 }
1750 }
1751
1752 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1753 info->shadow[i].grants_used = kzalloc(
1754 sizeof(info->shadow[i].grants_used[0]) * segs,
1755 GFP_NOIO);
1756 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO);
1757 if (info->max_indirect_segments)
1758 info->shadow[i].indirect_grants = kzalloc(
1759 sizeof(info->shadow[i].indirect_grants[0]) *
1760 INDIRECT_GREFS(segs),
1761 GFP_NOIO);
1762 if ((info->shadow[i].grants_used == NULL) ||
1763 (info->shadow[i].sg == NULL) ||
1764 (info->max_indirect_segments &&
1765 (info->shadow[i].indirect_grants == NULL)))
1766 goto out_of_memory;
1767 sg_init_table(info->shadow[i].sg, segs);
1768 }
1769
1770
1771 return 0;
1772
1773 out_of_memory:
1774 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1775 kfree(info->shadow[i].grants_used);
1776 info->shadow[i].grants_used = NULL;
1777 kfree(info->shadow[i].sg);
1778 info->shadow[i].sg = NULL;
1779 kfree(info->shadow[i].indirect_grants);
1780 info->shadow[i].indirect_grants = NULL;
1781 }
1782 if (!list_empty(&info->indirect_pages)) {
1783 struct page *indirect_page, *n;
1784 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
1785 list_del(&indirect_page->lru);
1786 __free_page(indirect_page);
1787 }
1788 }
1789 return -ENOMEM;
1790 }
1791
1792 /*
1793 * Gather all backend feature-*
1794 */
1795 static int blkfront_gather_backend_features(struct blkfront_info *info)
1796 {
1797 int err;
1798 int barrier, flush, discard, persistent;
1799 unsigned int indirect_segments;
1800
1801 info->feature_flush = 0;
1802
1803 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1804 "feature-barrier", "%d", &barrier,
1805 NULL);
1806
1807 /*
1808 * If there's no "feature-barrier" defined, then it means
1809 * we're dealing with a very old backend which writes
1810 * synchronously; nothing to do.
1811 *
1812 * If there are barriers, then we use flush.
1813 */
1814 if (!err && barrier)
1815 info->feature_flush = REQ_FLUSH | REQ_FUA;
1816 /*
1817 * And if there is "feature-flush-cache" use that above
1818 * barriers.
1819 */
1820 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1821 "feature-flush-cache", "%d", &flush,
1822 NULL);
1823
1824 if (!err && flush)
1825 info->feature_flush = REQ_FLUSH;
1826
1827 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1828 "feature-discard", "%d", &discard,
1829 NULL);
1830
1831 if (!err && discard)
1832 blkfront_setup_discard(info);
1833
1834 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1835 "feature-persistent", "%u", &persistent,
1836 NULL);
1837 if (err)
1838 info->feature_persistent = 0;
1839 else
1840 info->feature_persistent = persistent;
1841
1842 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1843 "feature-max-indirect-segments", "%u", &indirect_segments,
1844 NULL);
1845 if (err)
1846 info->max_indirect_segments = 0;
1847 else
1848 info->max_indirect_segments = min(indirect_segments,
1849 xen_blkif_max_segments);
1850
1851 return blkfront_setup_indirect(info);
1852 }
1853
1854 /*
1855 * Invoked when the backend is finally 'ready' (and has told produced
1856 * the details about the physical device - #sectors, size, etc).
1857 */
1858 static void blkfront_connect(struct blkfront_info *info)
1859 {
1860 unsigned long long sectors;
1861 unsigned long sector_size;
1862 unsigned int physical_sector_size;
1863 unsigned int binfo;
1864 int err;
1865
1866 switch (info->connected) {
1867 case BLKIF_STATE_CONNECTED:
1868 /*
1869 * Potentially, the back-end may be signalling
1870 * a capacity change; update the capacity.
1871 */
1872 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1873 "sectors", "%Lu", &sectors);
1874 if (XENBUS_EXIST_ERR(err))
1875 return;
1876 printk(KERN_INFO "Setting capacity to %Lu\n",
1877 sectors);
1878 set_capacity(info->gd, sectors);
1879 revalidate_disk(info->gd);
1880
1881 return;
1882 case BLKIF_STATE_SUSPENDED:
1883 /*
1884 * If we are recovering from suspension, we need to wait
1885 * for the backend to announce it's features before
1886 * reconnecting, at least we need to know if the backend
1887 * supports indirect descriptors, and how many.
1888 */
1889 blkif_recover(info);
1890 return;
1891
1892 default:
1893 break;
1894 }
1895
1896 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1897 __func__, info->xbdev->otherend);
1898
1899 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1900 "sectors", "%llu", &sectors,
1901 "info", "%u", &binfo,
1902 "sector-size", "%lu", &sector_size,
1903 NULL);
1904 if (err) {
1905 xenbus_dev_fatal(info->xbdev, err,
1906 "reading backend fields at %s",
1907 info->xbdev->otherend);
1908 return;
1909 }
1910
1911 /*
1912 * physcial-sector-size is a newer field, so old backends may not
1913 * provide this. Assume physical sector size to be the same as
1914 * sector_size in that case.
1915 */
1916 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1917 "physical-sector-size", "%u", &physical_sector_size);
1918 if (err != 1)
1919 physical_sector_size = sector_size;
1920
1921 err = blkfront_gather_backend_features(info);
1922 if (err) {
1923 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
1924 info->xbdev->otherend);
1925 return;
1926 }
1927
1928 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
1929 physical_sector_size);
1930 if (err) {
1931 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1932 info->xbdev->otherend);
1933 return;
1934 }
1935
1936 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1937
1938 /* Kick pending requests. */
1939 spin_lock_irq(&info->io_lock);
1940 info->connected = BLKIF_STATE_CONNECTED;
1941 kick_pending_request_queues(info);
1942 spin_unlock_irq(&info->io_lock);
1943
1944 add_disk(info->gd);
1945
1946 info->is_ready = 1;
1947 }
1948
1949 /**
1950 * Callback received when the backend's state changes.
1951 */
1952 static void blkback_changed(struct xenbus_device *dev,
1953 enum xenbus_state backend_state)
1954 {
1955 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1956
1957 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1958
1959 switch (backend_state) {
1960 case XenbusStateInitWait:
1961 if (dev->state != XenbusStateInitialising)
1962 break;
1963 if (talk_to_blkback(dev, info)) {
1964 kfree(info);
1965 dev_set_drvdata(&dev->dev, NULL);
1966 break;
1967 }
1968 case XenbusStateInitialising:
1969 case XenbusStateInitialised:
1970 case XenbusStateReconfiguring:
1971 case XenbusStateReconfigured:
1972 case XenbusStateUnknown:
1973 break;
1974
1975 case XenbusStateConnected:
1976 blkfront_connect(info);
1977 break;
1978
1979 case XenbusStateClosed:
1980 if (dev->state == XenbusStateClosed)
1981 break;
1982 /* Missed the backend's Closing state -- fallthrough */
1983 case XenbusStateClosing:
1984 blkfront_closing(info);
1985 break;
1986 }
1987 }
1988
1989 static int blkfront_remove(struct xenbus_device *xbdev)
1990 {
1991 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1992 struct block_device *bdev = NULL;
1993 struct gendisk *disk;
1994
1995 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1996
1997 blkif_free(info, 0);
1998
1999 mutex_lock(&info->mutex);
2000
2001 disk = info->gd;
2002 if (disk)
2003 bdev = bdget_disk(disk, 0);
2004
2005 info->xbdev = NULL;
2006 mutex_unlock(&info->mutex);
2007
2008 if (!bdev) {
2009 kfree(info);
2010 return 0;
2011 }
2012
2013 /*
2014 * The xbdev was removed before we reached the Closed
2015 * state. See if it's safe to remove the disk. If the bdev
2016 * isn't closed yet, we let release take care of it.
2017 */
2018
2019 mutex_lock(&bdev->bd_mutex);
2020 info = disk->private_data;
2021
2022 dev_warn(disk_to_dev(disk),
2023 "%s was hot-unplugged, %d stale handles\n",
2024 xbdev->nodename, bdev->bd_openers);
2025
2026 if (info && !bdev->bd_openers) {
2027 xlvbd_release_gendisk(info);
2028 disk->private_data = NULL;
2029 kfree(info);
2030 }
2031
2032 mutex_unlock(&bdev->bd_mutex);
2033 bdput(bdev);
2034
2035 return 0;
2036 }
2037
2038 static int blkfront_is_ready(struct xenbus_device *dev)
2039 {
2040 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2041
2042 return info->is_ready && info->xbdev;
2043 }
2044
2045 static int blkif_open(struct block_device *bdev, fmode_t mode)
2046 {
2047 struct gendisk *disk = bdev->bd_disk;
2048 struct blkfront_info *info;
2049 int err = 0;
2050
2051 mutex_lock(&blkfront_mutex);
2052
2053 info = disk->private_data;
2054 if (!info) {
2055 /* xbdev gone */
2056 err = -ERESTARTSYS;
2057 goto out;
2058 }
2059
2060 mutex_lock(&info->mutex);
2061
2062 if (!info->gd)
2063 /* xbdev is closed */
2064 err = -ERESTARTSYS;
2065
2066 mutex_unlock(&info->mutex);
2067
2068 out:
2069 mutex_unlock(&blkfront_mutex);
2070 return err;
2071 }
2072
2073 static void blkif_release(struct gendisk *disk, fmode_t mode)
2074 {
2075 struct blkfront_info *info = disk->private_data;
2076 struct block_device *bdev;
2077 struct xenbus_device *xbdev;
2078
2079 mutex_lock(&blkfront_mutex);
2080
2081 bdev = bdget_disk(disk, 0);
2082
2083 if (!bdev) {
2084 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2085 goto out_mutex;
2086 }
2087 if (bdev->bd_openers)
2088 goto out;
2089
2090 /*
2091 * Check if we have been instructed to close. We will have
2092 * deferred this request, because the bdev was still open.
2093 */
2094
2095 mutex_lock(&info->mutex);
2096 xbdev = info->xbdev;
2097
2098 if (xbdev && xbdev->state == XenbusStateClosing) {
2099 /* pending switch to state closed */
2100 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2101 xlvbd_release_gendisk(info);
2102 xenbus_frontend_closed(info->xbdev);
2103 }
2104
2105 mutex_unlock(&info->mutex);
2106
2107 if (!xbdev) {
2108 /* sudden device removal */
2109 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2110 xlvbd_release_gendisk(info);
2111 disk->private_data = NULL;
2112 kfree(info);
2113 }
2114
2115 out:
2116 bdput(bdev);
2117 out_mutex:
2118 mutex_unlock(&blkfront_mutex);
2119 }
2120
2121 static const struct block_device_operations xlvbd_block_fops =
2122 {
2123 .owner = THIS_MODULE,
2124 .open = blkif_open,
2125 .release = blkif_release,
2126 .getgeo = blkif_getgeo,
2127 .ioctl = blkif_ioctl,
2128 };
2129
2130
2131 static const struct xenbus_device_id blkfront_ids[] = {
2132 { "vbd" },
2133 { "" }
2134 };
2135
2136 static struct xenbus_driver blkfront_driver = {
2137 .ids = blkfront_ids,
2138 .probe = blkfront_probe,
2139 .remove = blkfront_remove,
2140 .resume = blkfront_resume,
2141 .otherend_changed = blkback_changed,
2142 .is_ready = blkfront_is_ready,
2143 };
2144
2145 static int __init xlblk_init(void)
2146 {
2147 int ret;
2148
2149 if (!xen_domain())
2150 return -ENODEV;
2151
2152 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER) {
2153 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2154 xen_blkif_max_ring_order, XENBUS_MAX_RING_PAGE_ORDER);
2155 xen_blkif_max_ring_order = 0;
2156 }
2157
2158 if (!xen_has_pv_disk_devices())
2159 return -ENODEV;
2160
2161 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2162 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2163 XENVBD_MAJOR, DEV_NAME);
2164 return -ENODEV;
2165 }
2166
2167 ret = xenbus_register_frontend(&blkfront_driver);
2168 if (ret) {
2169 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2170 return ret;
2171 }
2172
2173 return 0;
2174 }
2175 module_init(xlblk_init);
2176
2177
2178 static void __exit xlblk_exit(void)
2179 {
2180 xenbus_unregister_driver(&blkfront_driver);
2181 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2182 kfree(minors);
2183 }
2184 module_exit(xlblk_exit);
2185
2186 MODULE_DESCRIPTION("Xen virtual block device frontend");
2187 MODULE_LICENSE("GPL");
2188 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2189 MODULE_ALIAS("xen:vbd");
2190 MODULE_ALIAS("xenblk");
Linux with added FPC-III support