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