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Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
[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/llist.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 llist_node node;
72 };
73
74 struct blk_shadow {
75 struct blkif_request req;
76 struct request *request;
77 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
78 struct grant *grants_used[BLKIF_MAX_SEGMENTS_PER_REQUEST];
79 };
80
81 static DEFINE_MUTEX(blkfront_mutex);
82 static const struct block_device_operations xlvbd_block_fops;
83
84 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
85
86 /*
87 * We have one of these per vbd, whether ide, scsi or 'other'. They
88 * hang in private_data off the gendisk structure. We may end up
89 * putting all kinds of interesting stuff here :-)
90 */
91 struct blkfront_info
92 {
93 spinlock_t io_lock;
94 struct mutex mutex;
95 struct xenbus_device *xbdev;
96 struct gendisk *gd;
97 int vdevice;
98 blkif_vdev_t handle;
99 enum blkif_state connected;
100 int ring_ref;
101 struct blkif_front_ring ring;
102 struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
103 unsigned int evtchn, irq;
104 struct request_queue *rq;
105 struct work_struct work;
106 struct gnttab_free_callback callback;
107 struct blk_shadow shadow[BLK_RING_SIZE];
108 struct llist_head persistent_gnts;
109 unsigned int persistent_gnts_c;
110 unsigned long shadow_free;
111 unsigned int feature_flush;
112 unsigned int flush_op;
113 unsigned int feature_discard:1;
114 unsigned int feature_secdiscard:1;
115 unsigned int discard_granularity;
116 unsigned int discard_alignment;
117 unsigned int feature_persistent:1;
118 int is_ready;
119 };
120
121 static unsigned int nr_minors;
122 static unsigned long *minors;
123 static DEFINE_SPINLOCK(minor_lock);
124
125 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
126 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
127 #define GRANT_INVALID_REF 0
128
129 #define PARTS_PER_DISK 16
130 #define PARTS_PER_EXT_DISK 256
131
132 #define BLKIF_MAJOR(dev) ((dev)>>8)
133 #define BLKIF_MINOR(dev) ((dev) & 0xff)
134
135 #define EXT_SHIFT 28
136 #define EXTENDED (1<<EXT_SHIFT)
137 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
138 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
139 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
140 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
141 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
142 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
143
144 #define DEV_NAME "xvd" /* name in /dev */
145
146 static int get_id_from_freelist(struct blkfront_info *info)
147 {
148 unsigned long free = info->shadow_free;
149 BUG_ON(free >= BLK_RING_SIZE);
150 info->shadow_free = info->shadow[free].req.u.rw.id;
151 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
152 return free;
153 }
154
155 static int add_id_to_freelist(struct blkfront_info *info,
156 unsigned long id)
157 {
158 if (info->shadow[id].req.u.rw.id != id)
159 return -EINVAL;
160 if (info->shadow[id].request == NULL)
161 return -EINVAL;
162 info->shadow[id].req.u.rw.id = info->shadow_free;
163 info->shadow[id].request = NULL;
164 info->shadow_free = id;
165 return 0;
166 }
167
168 static const char *op_name(int op)
169 {
170 static const char *const names[] = {
171 [BLKIF_OP_READ] = "read",
172 [BLKIF_OP_WRITE] = "write",
173 [BLKIF_OP_WRITE_BARRIER] = "barrier",
174 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
175 [BLKIF_OP_DISCARD] = "discard" };
176
177 if (op < 0 || op >= ARRAY_SIZE(names))
178 return "unknown";
179
180 if (!names[op])
181 return "reserved";
182
183 return names[op];
184 }
185 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
186 {
187 unsigned int end = minor + nr;
188 int rc;
189
190 if (end > nr_minors) {
191 unsigned long *bitmap, *old;
192
193 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
194 GFP_KERNEL);
195 if (bitmap == NULL)
196 return -ENOMEM;
197
198 spin_lock(&minor_lock);
199 if (end > nr_minors) {
200 old = minors;
201 memcpy(bitmap, minors,
202 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
203 minors = bitmap;
204 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
205 } else
206 old = bitmap;
207 spin_unlock(&minor_lock);
208 kfree(old);
209 }
210
211 spin_lock(&minor_lock);
212 if (find_next_bit(minors, end, minor) >= end) {
213 bitmap_set(minors, minor, nr);
214 rc = 0;
215 } else
216 rc = -EBUSY;
217 spin_unlock(&minor_lock);
218
219 return rc;
220 }
221
222 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
223 {
224 unsigned int end = minor + nr;
225
226 BUG_ON(end > nr_minors);
227 spin_lock(&minor_lock);
228 bitmap_clear(minors, minor, nr);
229 spin_unlock(&minor_lock);
230 }
231
232 static void blkif_restart_queue_callback(void *arg)
233 {
234 struct blkfront_info *info = (struct blkfront_info *)arg;
235 schedule_work(&info->work);
236 }
237
238 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
239 {
240 /* We don't have real geometry info, but let's at least return
241 values consistent with the size of the device */
242 sector_t nsect = get_capacity(bd->bd_disk);
243 sector_t cylinders = nsect;
244
245 hg->heads = 0xff;
246 hg->sectors = 0x3f;
247 sector_div(cylinders, hg->heads * hg->sectors);
248 hg->cylinders = cylinders;
249 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
250 hg->cylinders = 0xffff;
251 return 0;
252 }
253
254 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
255 unsigned command, unsigned long argument)
256 {
257 struct blkfront_info *info = bdev->bd_disk->private_data;
258 int i;
259
260 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
261 command, (long)argument);
262
263 switch (command) {
264 case CDROMMULTISESSION:
265 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
266 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
267 if (put_user(0, (char __user *)(argument + i)))
268 return -EFAULT;
269 return 0;
270
271 case CDROM_GET_CAPABILITY: {
272 struct gendisk *gd = info->gd;
273 if (gd->flags & GENHD_FL_CD)
274 return 0;
275 return -EINVAL;
276 }
277
278 default:
279 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
280 command);*/
281 return -EINVAL; /* same return as native Linux */
282 }
283
284 return 0;
285 }
286
287 /*
288 * Generate a Xen blkfront IO request from a blk layer request. Reads
289 * and writes are handled as expected.
290 *
291 * @req: a request struct
292 */
293 static int blkif_queue_request(struct request *req)
294 {
295 struct blkfront_info *info = req->rq_disk->private_data;
296 unsigned long buffer_mfn;
297 struct blkif_request *ring_req;
298 unsigned long id;
299 unsigned int fsect, lsect;
300 int i, ref;
301
302 /*
303 * Used to store if we are able to queue the request by just using
304 * existing persistent grants, or if we have to get new grants,
305 * as there are not sufficiently many free.
306 */
307 bool new_persistent_gnts;
308 grant_ref_t gref_head;
309 struct page *granted_page;
310 struct grant *gnt_list_entry = NULL;
311 struct scatterlist *sg;
312
313 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
314 return 1;
315
316 /* Check if we have enought grants to allocate a requests */
317 if (info->persistent_gnts_c < BLKIF_MAX_SEGMENTS_PER_REQUEST) {
318 new_persistent_gnts = 1;
319 if (gnttab_alloc_grant_references(
320 BLKIF_MAX_SEGMENTS_PER_REQUEST - info->persistent_gnts_c,
321 &gref_head) < 0) {
322 gnttab_request_free_callback(
323 &info->callback,
324 blkif_restart_queue_callback,
325 info,
326 BLKIF_MAX_SEGMENTS_PER_REQUEST);
327 return 1;
328 }
329 } else
330 new_persistent_gnts = 0;
331
332 /* Fill out a communications ring structure. */
333 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
334 id = get_id_from_freelist(info);
335 info->shadow[id].request = req;
336
337 ring_req->u.rw.id = id;
338 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
339 ring_req->u.rw.handle = info->handle;
340
341 ring_req->operation = rq_data_dir(req) ?
342 BLKIF_OP_WRITE : BLKIF_OP_READ;
343
344 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
345 /*
346 * Ideally we can do an unordered flush-to-disk. In case the
347 * backend onlysupports barriers, use that. A barrier request
348 * a superset of FUA, so we can implement it the same
349 * way. (It's also a FLUSH+FUA, since it is
350 * guaranteed ordered WRT previous writes.)
351 */
352 ring_req->operation = info->flush_op;
353 }
354
355 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
356 /* id, sector_number and handle are set above. */
357 ring_req->operation = BLKIF_OP_DISCARD;
358 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
359 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
360 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
361 else
362 ring_req->u.discard.flag = 0;
363 } else {
364 ring_req->u.rw.nr_segments = blk_rq_map_sg(req->q, req,
365 info->sg);
366 BUG_ON(ring_req->u.rw.nr_segments >
367 BLKIF_MAX_SEGMENTS_PER_REQUEST);
368
369 for_each_sg(info->sg, sg, ring_req->u.rw.nr_segments, i) {
370 fsect = sg->offset >> 9;
371 lsect = fsect + (sg->length >> 9) - 1;
372
373 if (info->persistent_gnts_c) {
374 BUG_ON(llist_empty(&info->persistent_gnts));
375 gnt_list_entry = llist_entry(
376 llist_del_first(&info->persistent_gnts),
377 struct grant, node);
378
379 ref = gnt_list_entry->gref;
380 buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
381 info->persistent_gnts_c--;
382 } else {
383 ref = gnttab_claim_grant_reference(&gref_head);
384 BUG_ON(ref == -ENOSPC);
385
386 gnt_list_entry =
387 kmalloc(sizeof(struct grant),
388 GFP_ATOMIC);
389 if (!gnt_list_entry)
390 return -ENOMEM;
391
392 granted_page = alloc_page(GFP_ATOMIC);
393 if (!granted_page) {
394 kfree(gnt_list_entry);
395 return -ENOMEM;
396 }
397
398 gnt_list_entry->pfn =
399 page_to_pfn(granted_page);
400 gnt_list_entry->gref = ref;
401
402 buffer_mfn = pfn_to_mfn(page_to_pfn(
403 granted_page));
404 gnttab_grant_foreign_access_ref(ref,
405 info->xbdev->otherend_id,
406 buffer_mfn, 0);
407 }
408
409 info->shadow[id].grants_used[i] = gnt_list_entry;
410
411 if (rq_data_dir(req)) {
412 char *bvec_data;
413 void *shared_data;
414
415 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
416
417 shared_data = kmap_atomic(
418 pfn_to_page(gnt_list_entry->pfn));
419 bvec_data = kmap_atomic(sg_page(sg));
420
421 /*
422 * this does not wipe data stored outside the
423 * range sg->offset..sg->offset+sg->length.
424 * Therefore, blkback *could* see data from
425 * previous requests. This is OK as long as
426 * persistent grants are shared with just one
427 * domain. It may need refactoring if this
428 * changes
429 */
430 memcpy(shared_data + sg->offset,
431 bvec_data + sg->offset,
432 sg->length);
433
434 kunmap_atomic(bvec_data);
435 kunmap_atomic(shared_data);
436 }
437
438 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
439 ring_req->u.rw.seg[i] =
440 (struct blkif_request_segment) {
441 .gref = ref,
442 .first_sect = fsect,
443 .last_sect = lsect };
444 }
445 }
446
447 info->ring.req_prod_pvt++;
448
449 /* Keep a private copy so we can reissue requests when recovering. */
450 info->shadow[id].req = *ring_req;
451
452 if (new_persistent_gnts)
453 gnttab_free_grant_references(gref_head);
454
455 return 0;
456 }
457
458
459 static inline void flush_requests(struct blkfront_info *info)
460 {
461 int notify;
462
463 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
464
465 if (notify)
466 notify_remote_via_irq(info->irq);
467 }
468
469 /*
470 * do_blkif_request
471 * read a block; request is in a request queue
472 */
473 static void do_blkif_request(struct request_queue *rq)
474 {
475 struct blkfront_info *info = NULL;
476 struct request *req;
477 int queued;
478
479 pr_debug("Entered do_blkif_request\n");
480
481 queued = 0;
482
483 while ((req = blk_peek_request(rq)) != NULL) {
484 info = req->rq_disk->private_data;
485
486 if (RING_FULL(&info->ring))
487 goto wait;
488
489 blk_start_request(req);
490
491 if ((req->cmd_type != REQ_TYPE_FS) ||
492 ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) &&
493 !info->flush_op)) {
494 __blk_end_request_all(req, -EIO);
495 continue;
496 }
497
498 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
499 "(%u/%u) buffer:%p [%s]\n",
500 req, req->cmd, (unsigned long)blk_rq_pos(req),
501 blk_rq_cur_sectors(req), blk_rq_sectors(req),
502 req->buffer, rq_data_dir(req) ? "write" : "read");
503
504 if (blkif_queue_request(req)) {
505 blk_requeue_request(rq, req);
506 wait:
507 /* Avoid pointless unplugs. */
508 blk_stop_queue(rq);
509 break;
510 }
511
512 queued++;
513 }
514
515 if (queued != 0)
516 flush_requests(info);
517 }
518
519 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
520 {
521 struct request_queue *rq;
522 struct blkfront_info *info = gd->private_data;
523
524 rq = blk_init_queue(do_blkif_request, &info->io_lock);
525 if (rq == NULL)
526 return -1;
527
528 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
529
530 if (info->feature_discard) {
531 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
532 blk_queue_max_discard_sectors(rq, get_capacity(gd));
533 rq->limits.discard_granularity = info->discard_granularity;
534 rq->limits.discard_alignment = info->discard_alignment;
535 if (info->feature_secdiscard)
536 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
537 }
538
539 /* Hard sector size and max sectors impersonate the equiv. hardware. */
540 blk_queue_logical_block_size(rq, sector_size);
541 blk_queue_max_hw_sectors(rq, 512);
542
543 /* Each segment in a request is up to an aligned page in size. */
544 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
545 blk_queue_max_segment_size(rq, PAGE_SIZE);
546
547 /* Ensure a merged request will fit in a single I/O ring slot. */
548 blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
549
550 /* Make sure buffer addresses are sector-aligned. */
551 blk_queue_dma_alignment(rq, 511);
552
553 /* Make sure we don't use bounce buffers. */
554 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
555
556 gd->queue = rq;
557
558 return 0;
559 }
560
561
562 static void xlvbd_flush(struct blkfront_info *info)
563 {
564 blk_queue_flush(info->rq, info->feature_flush);
565 printk(KERN_INFO "blkfront: %s: %s: %s %s\n",
566 info->gd->disk_name,
567 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
568 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
569 "flush diskcache" : "barrier or flush"),
570 info->feature_flush ? "enabled" : "disabled",
571 info->feature_persistent ? "using persistent grants" : "");
572 }
573
574 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
575 {
576 int major;
577 major = BLKIF_MAJOR(vdevice);
578 *minor = BLKIF_MINOR(vdevice);
579 switch (major) {
580 case XEN_IDE0_MAJOR:
581 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
582 *minor = ((*minor / 64) * PARTS_PER_DISK) +
583 EMULATED_HD_DISK_MINOR_OFFSET;
584 break;
585 case XEN_IDE1_MAJOR:
586 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
587 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
588 EMULATED_HD_DISK_MINOR_OFFSET;
589 break;
590 case XEN_SCSI_DISK0_MAJOR:
591 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
592 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
593 break;
594 case XEN_SCSI_DISK1_MAJOR:
595 case XEN_SCSI_DISK2_MAJOR:
596 case XEN_SCSI_DISK3_MAJOR:
597 case XEN_SCSI_DISK4_MAJOR:
598 case XEN_SCSI_DISK5_MAJOR:
599 case XEN_SCSI_DISK6_MAJOR:
600 case XEN_SCSI_DISK7_MAJOR:
601 *offset = (*minor / PARTS_PER_DISK) +
602 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
603 EMULATED_SD_DISK_NAME_OFFSET;
604 *minor = *minor +
605 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
606 EMULATED_SD_DISK_MINOR_OFFSET;
607 break;
608 case XEN_SCSI_DISK8_MAJOR:
609 case XEN_SCSI_DISK9_MAJOR:
610 case XEN_SCSI_DISK10_MAJOR:
611 case XEN_SCSI_DISK11_MAJOR:
612 case XEN_SCSI_DISK12_MAJOR:
613 case XEN_SCSI_DISK13_MAJOR:
614 case XEN_SCSI_DISK14_MAJOR:
615 case XEN_SCSI_DISK15_MAJOR:
616 *offset = (*minor / PARTS_PER_DISK) +
617 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
618 EMULATED_SD_DISK_NAME_OFFSET;
619 *minor = *minor +
620 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
621 EMULATED_SD_DISK_MINOR_OFFSET;
622 break;
623 case XENVBD_MAJOR:
624 *offset = *minor / PARTS_PER_DISK;
625 break;
626 default:
627 printk(KERN_WARNING "blkfront: your disk configuration is "
628 "incorrect, please use an xvd device instead\n");
629 return -ENODEV;
630 }
631 return 0;
632 }
633
634 static char *encode_disk_name(char *ptr, unsigned int n)
635 {
636 if (n >= 26)
637 ptr = encode_disk_name(ptr, n / 26 - 1);
638 *ptr = 'a' + n % 26;
639 return ptr + 1;
640 }
641
642 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
643 struct blkfront_info *info,
644 u16 vdisk_info, u16 sector_size)
645 {
646 struct gendisk *gd;
647 int nr_minors = 1;
648 int err;
649 unsigned int offset;
650 int minor;
651 int nr_parts;
652 char *ptr;
653
654 BUG_ON(info->gd != NULL);
655 BUG_ON(info->rq != NULL);
656
657 if ((info->vdevice>>EXT_SHIFT) > 1) {
658 /* this is above the extended range; something is wrong */
659 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
660 return -ENODEV;
661 }
662
663 if (!VDEV_IS_EXTENDED(info->vdevice)) {
664 err = xen_translate_vdev(info->vdevice, &minor, &offset);
665 if (err)
666 return err;
667 nr_parts = PARTS_PER_DISK;
668 } else {
669 minor = BLKIF_MINOR_EXT(info->vdevice);
670 nr_parts = PARTS_PER_EXT_DISK;
671 offset = minor / nr_parts;
672 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
673 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
674 "emulated IDE disks,\n\t choose an xvd device name"
675 "from xvde on\n", info->vdevice);
676 }
677 if (minor >> MINORBITS) {
678 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
679 info->vdevice, minor);
680 return -ENODEV;
681 }
682
683 if ((minor % nr_parts) == 0)
684 nr_minors = nr_parts;
685
686 err = xlbd_reserve_minors(minor, nr_minors);
687 if (err)
688 goto out;
689 err = -ENODEV;
690
691 gd = alloc_disk(nr_minors);
692 if (gd == NULL)
693 goto release;
694
695 strcpy(gd->disk_name, DEV_NAME);
696 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
697 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
698 if (nr_minors > 1)
699 *ptr = 0;
700 else
701 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
702 "%d", minor & (nr_parts - 1));
703
704 gd->major = XENVBD_MAJOR;
705 gd->first_minor = minor;
706 gd->fops = &xlvbd_block_fops;
707 gd->private_data = info;
708 gd->driverfs_dev = &(info->xbdev->dev);
709 set_capacity(gd, capacity);
710
711 if (xlvbd_init_blk_queue(gd, sector_size)) {
712 del_gendisk(gd);
713 goto release;
714 }
715
716 info->rq = gd->queue;
717 info->gd = gd;
718
719 xlvbd_flush(info);
720
721 if (vdisk_info & VDISK_READONLY)
722 set_disk_ro(gd, 1);
723
724 if (vdisk_info & VDISK_REMOVABLE)
725 gd->flags |= GENHD_FL_REMOVABLE;
726
727 if (vdisk_info & VDISK_CDROM)
728 gd->flags |= GENHD_FL_CD;
729
730 return 0;
731
732 release:
733 xlbd_release_minors(minor, nr_minors);
734 out:
735 return err;
736 }
737
738 static void xlvbd_release_gendisk(struct blkfront_info *info)
739 {
740 unsigned int minor, nr_minors;
741 unsigned long flags;
742
743 if (info->rq == NULL)
744 return;
745
746 spin_lock_irqsave(&info->io_lock, flags);
747
748 /* No more blkif_request(). */
749 blk_stop_queue(info->rq);
750
751 /* No more gnttab callback work. */
752 gnttab_cancel_free_callback(&info->callback);
753 spin_unlock_irqrestore(&info->io_lock, flags);
754
755 /* Flush gnttab callback work. Must be done with no locks held. */
756 flush_work(&info->work);
757
758 del_gendisk(info->gd);
759
760 minor = info->gd->first_minor;
761 nr_minors = info->gd->minors;
762 xlbd_release_minors(minor, nr_minors);
763
764 blk_cleanup_queue(info->rq);
765 info->rq = NULL;
766
767 put_disk(info->gd);
768 info->gd = NULL;
769 }
770
771 static void kick_pending_request_queues(struct blkfront_info *info)
772 {
773 if (!RING_FULL(&info->ring)) {
774 /* Re-enable calldowns. */
775 blk_start_queue(info->rq);
776 /* Kick things off immediately. */
777 do_blkif_request(info->rq);
778 }
779 }
780
781 static void blkif_restart_queue(struct work_struct *work)
782 {
783 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
784
785 spin_lock_irq(&info->io_lock);
786 if (info->connected == BLKIF_STATE_CONNECTED)
787 kick_pending_request_queues(info);
788 spin_unlock_irq(&info->io_lock);
789 }
790
791 static void blkif_free(struct blkfront_info *info, int suspend)
792 {
793 struct llist_node *all_gnts;
794 struct grant *persistent_gnt, *tmp;
795 struct llist_node *n;
796
797 /* Prevent new requests being issued until we fix things up. */
798 spin_lock_irq(&info->io_lock);
799 info->connected = suspend ?
800 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
801 /* No more blkif_request(). */
802 if (info->rq)
803 blk_stop_queue(info->rq);
804
805 /* Remove all persistent grants */
806 if (info->persistent_gnts_c) {
807 all_gnts = llist_del_all(&info->persistent_gnts);
808 persistent_gnt = llist_entry(all_gnts, typeof(*(persistent_gnt)), node);
809 while (persistent_gnt) {
810 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
811 __free_page(pfn_to_page(persistent_gnt->pfn));
812 tmp = persistent_gnt;
813 n = persistent_gnt->node.next;
814 if (n)
815 persistent_gnt = llist_entry(n, typeof(*(persistent_gnt)), node);
816 else
817 persistent_gnt = NULL;
818 kfree(tmp);
819 }
820 info->persistent_gnts_c = 0;
821 }
822
823 /* No more gnttab callback work. */
824 gnttab_cancel_free_callback(&info->callback);
825 spin_unlock_irq(&info->io_lock);
826
827 /* Flush gnttab callback work. Must be done with no locks held. */
828 flush_work(&info->work);
829
830 /* Free resources associated with old device channel. */
831 if (info->ring_ref != GRANT_INVALID_REF) {
832 gnttab_end_foreign_access(info->ring_ref, 0,
833 (unsigned long)info->ring.sring);
834 info->ring_ref = GRANT_INVALID_REF;
835 info->ring.sring = NULL;
836 }
837 if (info->irq)
838 unbind_from_irqhandler(info->irq, info);
839 info->evtchn = info->irq = 0;
840
841 }
842
843 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
844 struct blkif_response *bret)
845 {
846 int i = 0;
847 struct bio_vec *bvec;
848 struct req_iterator iter;
849 unsigned long flags;
850 char *bvec_data;
851 void *shared_data;
852 unsigned int offset = 0;
853
854 if (bret->operation == BLKIF_OP_READ) {
855 /*
856 * Copy the data received from the backend into the bvec.
857 * Since bv_offset can be different than 0, and bv_len different
858 * than PAGE_SIZE, we have to keep track of the current offset,
859 * to be sure we are copying the data from the right shared page.
860 */
861 rq_for_each_segment(bvec, s->request, iter) {
862 BUG_ON((bvec->bv_offset + bvec->bv_len) > PAGE_SIZE);
863 if (bvec->bv_offset < offset)
864 i++;
865 BUG_ON(i >= s->req.u.rw.nr_segments);
866 shared_data = kmap_atomic(
867 pfn_to_page(s->grants_used[i]->pfn));
868 bvec_data = bvec_kmap_irq(bvec, &flags);
869 memcpy(bvec_data, shared_data + bvec->bv_offset,
870 bvec->bv_len);
871 bvec_kunmap_irq(bvec_data, &flags);
872 kunmap_atomic(shared_data);
873 offset = bvec->bv_offset + bvec->bv_len;
874 }
875 }
876 /* Add the persistent grant into the list of free grants */
877 for (i = 0; i < s->req.u.rw.nr_segments; i++) {
878 llist_add(&s->grants_used[i]->node, &info->persistent_gnts);
879 info->persistent_gnts_c++;
880 }
881 }
882
883 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
884 {
885 struct request *req;
886 struct blkif_response *bret;
887 RING_IDX i, rp;
888 unsigned long flags;
889 struct blkfront_info *info = (struct blkfront_info *)dev_id;
890 int error;
891
892 spin_lock_irqsave(&info->io_lock, flags);
893
894 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
895 spin_unlock_irqrestore(&info->io_lock, flags);
896 return IRQ_HANDLED;
897 }
898
899 again:
900 rp = info->ring.sring->rsp_prod;
901 rmb(); /* Ensure we see queued responses up to 'rp'. */
902
903 for (i = info->ring.rsp_cons; i != rp; i++) {
904 unsigned long id;
905
906 bret = RING_GET_RESPONSE(&info->ring, i);
907 id = bret->id;
908 /*
909 * The backend has messed up and given us an id that we would
910 * never have given to it (we stamp it up to BLK_RING_SIZE -
911 * look in get_id_from_freelist.
912 */
913 if (id >= BLK_RING_SIZE) {
914 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
915 info->gd->disk_name, op_name(bret->operation), id);
916 /* We can't safely get the 'struct request' as
917 * the id is busted. */
918 continue;
919 }
920 req = info->shadow[id].request;
921
922 if (bret->operation != BLKIF_OP_DISCARD)
923 blkif_completion(&info->shadow[id], info, bret);
924
925 if (add_id_to_freelist(info, id)) {
926 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
927 info->gd->disk_name, op_name(bret->operation), id);
928 continue;
929 }
930
931 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
932 switch (bret->operation) {
933 case BLKIF_OP_DISCARD:
934 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
935 struct request_queue *rq = info->rq;
936 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
937 info->gd->disk_name, op_name(bret->operation));
938 error = -EOPNOTSUPP;
939 info->feature_discard = 0;
940 info->feature_secdiscard = 0;
941 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
942 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
943 }
944 __blk_end_request_all(req, error);
945 break;
946 case BLKIF_OP_FLUSH_DISKCACHE:
947 case BLKIF_OP_WRITE_BARRIER:
948 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
949 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
950 info->gd->disk_name, op_name(bret->operation));
951 error = -EOPNOTSUPP;
952 }
953 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
954 info->shadow[id].req.u.rw.nr_segments == 0)) {
955 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
956 info->gd->disk_name, op_name(bret->operation));
957 error = -EOPNOTSUPP;
958 }
959 if (unlikely(error)) {
960 if (error == -EOPNOTSUPP)
961 error = 0;
962 info->feature_flush = 0;
963 info->flush_op = 0;
964 xlvbd_flush(info);
965 }
966 /* fall through */
967 case BLKIF_OP_READ:
968 case BLKIF_OP_WRITE:
969 if (unlikely(bret->status != BLKIF_RSP_OKAY))
970 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
971 "request: %x\n", bret->status);
972
973 __blk_end_request_all(req, error);
974 break;
975 default:
976 BUG();
977 }
978 }
979
980 info->ring.rsp_cons = i;
981
982 if (i != info->ring.req_prod_pvt) {
983 int more_to_do;
984 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
985 if (more_to_do)
986 goto again;
987 } else
988 info->ring.sring->rsp_event = i + 1;
989
990 kick_pending_request_queues(info);
991
992 spin_unlock_irqrestore(&info->io_lock, flags);
993
994 return IRQ_HANDLED;
995 }
996
997
998 static int setup_blkring(struct xenbus_device *dev,
999 struct blkfront_info *info)
1000 {
1001 struct blkif_sring *sring;
1002 int err;
1003
1004 info->ring_ref = GRANT_INVALID_REF;
1005
1006 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
1007 if (!sring) {
1008 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1009 return -ENOMEM;
1010 }
1011 SHARED_RING_INIT(sring);
1012 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
1013
1014 sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
1015
1016 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
1017 if (err < 0) {
1018 free_page((unsigned long)sring);
1019 info->ring.sring = NULL;
1020 goto fail;
1021 }
1022 info->ring_ref = err;
1023
1024 err = xenbus_alloc_evtchn(dev, &info->evtchn);
1025 if (err)
1026 goto fail;
1027
1028 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
1029 "blkif", info);
1030 if (err <= 0) {
1031 xenbus_dev_fatal(dev, err,
1032 "bind_evtchn_to_irqhandler failed");
1033 goto fail;
1034 }
1035 info->irq = err;
1036
1037 return 0;
1038 fail:
1039 blkif_free(info, 0);
1040 return err;
1041 }
1042
1043
1044 /* Common code used when first setting up, and when resuming. */
1045 static int talk_to_blkback(struct xenbus_device *dev,
1046 struct blkfront_info *info)
1047 {
1048 const char *message = NULL;
1049 struct xenbus_transaction xbt;
1050 int err;
1051
1052 /* Create shared ring, alloc event channel. */
1053 err = setup_blkring(dev, info);
1054 if (err)
1055 goto out;
1056
1057 again:
1058 err = xenbus_transaction_start(&xbt);
1059 if (err) {
1060 xenbus_dev_fatal(dev, err, "starting transaction");
1061 goto destroy_blkring;
1062 }
1063
1064 err = xenbus_printf(xbt, dev->nodename,
1065 "ring-ref", "%u", info->ring_ref);
1066 if (err) {
1067 message = "writing ring-ref";
1068 goto abort_transaction;
1069 }
1070 err = xenbus_printf(xbt, dev->nodename,
1071 "event-channel", "%u", info->evtchn);
1072 if (err) {
1073 message = "writing event-channel";
1074 goto abort_transaction;
1075 }
1076 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1077 XEN_IO_PROTO_ABI_NATIVE);
1078 if (err) {
1079 message = "writing protocol";
1080 goto abort_transaction;
1081 }
1082 err = xenbus_printf(xbt, dev->nodename,
1083 "feature-persistent", "%u", 1);
1084 if (err)
1085 dev_warn(&dev->dev,
1086 "writing persistent grants feature to xenbus");
1087
1088 err = xenbus_transaction_end(xbt, 0);
1089 if (err) {
1090 if (err == -EAGAIN)
1091 goto again;
1092 xenbus_dev_fatal(dev, err, "completing transaction");
1093 goto destroy_blkring;
1094 }
1095
1096 xenbus_switch_state(dev, XenbusStateInitialised);
1097
1098 return 0;
1099
1100 abort_transaction:
1101 xenbus_transaction_end(xbt, 1);
1102 if (message)
1103 xenbus_dev_fatal(dev, err, "%s", message);
1104 destroy_blkring:
1105 blkif_free(info, 0);
1106 out:
1107 return err;
1108 }
1109
1110 /**
1111 * Entry point to this code when a new device is created. Allocate the basic
1112 * structures and the ring buffer for communication with the backend, and
1113 * inform the backend of the appropriate details for those. Switch to
1114 * Initialised state.
1115 */
1116 static int blkfront_probe(struct xenbus_device *dev,
1117 const struct xenbus_device_id *id)
1118 {
1119 int err, vdevice, i;
1120 struct blkfront_info *info;
1121
1122 /* FIXME: Use dynamic device id if this is not set. */
1123 err = xenbus_scanf(XBT_NIL, dev->nodename,
1124 "virtual-device", "%i", &vdevice);
1125 if (err != 1) {
1126 /* go looking in the extended area instead */
1127 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1128 "%i", &vdevice);
1129 if (err != 1) {
1130 xenbus_dev_fatal(dev, err, "reading virtual-device");
1131 return err;
1132 }
1133 }
1134
1135 if (xen_hvm_domain()) {
1136 char *type;
1137 int len;
1138 /* no unplug has been done: do not hook devices != xen vbds */
1139 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
1140 int major;
1141
1142 if (!VDEV_IS_EXTENDED(vdevice))
1143 major = BLKIF_MAJOR(vdevice);
1144 else
1145 major = XENVBD_MAJOR;
1146
1147 if (major != XENVBD_MAJOR) {
1148 printk(KERN_INFO
1149 "%s: HVM does not support vbd %d as xen block device\n",
1150 __FUNCTION__, vdevice);
1151 return -ENODEV;
1152 }
1153 }
1154 /* do not create a PV cdrom device if we are an HVM guest */
1155 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1156 if (IS_ERR(type))
1157 return -ENODEV;
1158 if (strncmp(type, "cdrom", 5) == 0) {
1159 kfree(type);
1160 return -ENODEV;
1161 }
1162 kfree(type);
1163 }
1164 info = kzalloc(sizeof(*info), GFP_KERNEL);
1165 if (!info) {
1166 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1167 return -ENOMEM;
1168 }
1169
1170 mutex_init(&info->mutex);
1171 spin_lock_init(&info->io_lock);
1172 info->xbdev = dev;
1173 info->vdevice = vdevice;
1174 init_llist_head(&info->persistent_gnts);
1175 info->persistent_gnts_c = 0;
1176 info->connected = BLKIF_STATE_DISCONNECTED;
1177 INIT_WORK(&info->work, blkif_restart_queue);
1178
1179 for (i = 0; i < BLK_RING_SIZE; i++)
1180 info->shadow[i].req.u.rw.id = i+1;
1181 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1182
1183 /* Front end dir is a number, which is used as the id. */
1184 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1185 dev_set_drvdata(&dev->dev, info);
1186
1187 err = talk_to_blkback(dev, info);
1188 if (err) {
1189 kfree(info);
1190 dev_set_drvdata(&dev->dev, NULL);
1191 return err;
1192 }
1193
1194 return 0;
1195 }
1196
1197
1198 static int blkif_recover(struct blkfront_info *info)
1199 {
1200 int i;
1201 struct blkif_request *req;
1202 struct blk_shadow *copy;
1203 int j;
1204
1205 /* Stage 1: Make a safe copy of the shadow state. */
1206 copy = kmalloc(sizeof(info->shadow),
1207 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1208 if (!copy)
1209 return -ENOMEM;
1210 memcpy(copy, info->shadow, sizeof(info->shadow));
1211
1212 /* Stage 2: Set up free list. */
1213 memset(&info->shadow, 0, sizeof(info->shadow));
1214 for (i = 0; i < BLK_RING_SIZE; i++)
1215 info->shadow[i].req.u.rw.id = i+1;
1216 info->shadow_free = info->ring.req_prod_pvt;
1217 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1218
1219 /* Stage 3: Find pending requests and requeue them. */
1220 for (i = 0; i < BLK_RING_SIZE; i++) {
1221 /* Not in use? */
1222 if (!copy[i].request)
1223 continue;
1224
1225 /* Grab a request slot and copy shadow state into it. */
1226 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
1227 *req = copy[i].req;
1228
1229 /* We get a new request id, and must reset the shadow state. */
1230 req->u.rw.id = get_id_from_freelist(info);
1231 memcpy(&info->shadow[req->u.rw.id], &copy[i], sizeof(copy[i]));
1232
1233 if (req->operation != BLKIF_OP_DISCARD) {
1234 /* Rewrite any grant references invalidated by susp/resume. */
1235 for (j = 0; j < req->u.rw.nr_segments; j++)
1236 gnttab_grant_foreign_access_ref(
1237 req->u.rw.seg[j].gref,
1238 info->xbdev->otherend_id,
1239 pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]),
1240 0);
1241 }
1242 info->shadow[req->u.rw.id].req = *req;
1243
1244 info->ring.req_prod_pvt++;
1245 }
1246
1247 kfree(copy);
1248
1249 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1250
1251 spin_lock_irq(&info->io_lock);
1252
1253 /* Now safe for us to use the shared ring */
1254 info->connected = BLKIF_STATE_CONNECTED;
1255
1256 /* Send off requeued requests */
1257 flush_requests(info);
1258
1259 /* Kick any other new requests queued since we resumed */
1260 kick_pending_request_queues(info);
1261
1262 spin_unlock_irq(&info->io_lock);
1263
1264 return 0;
1265 }
1266
1267 /**
1268 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1269 * driver restart. We tear down our blkif structure and recreate it, but
1270 * leave the device-layer structures intact so that this is transparent to the
1271 * rest of the kernel.
1272 */
1273 static int blkfront_resume(struct xenbus_device *dev)
1274 {
1275 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1276 int err;
1277
1278 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1279
1280 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1281
1282 err = talk_to_blkback(dev, info);
1283 if (info->connected == BLKIF_STATE_SUSPENDED && !err)
1284 err = blkif_recover(info);
1285
1286 return err;
1287 }
1288
1289 static void
1290 blkfront_closing(struct blkfront_info *info)
1291 {
1292 struct xenbus_device *xbdev = info->xbdev;
1293 struct block_device *bdev = NULL;
1294
1295 mutex_lock(&info->mutex);
1296
1297 if (xbdev->state == XenbusStateClosing) {
1298 mutex_unlock(&info->mutex);
1299 return;
1300 }
1301
1302 if (info->gd)
1303 bdev = bdget_disk(info->gd, 0);
1304
1305 mutex_unlock(&info->mutex);
1306
1307 if (!bdev) {
1308 xenbus_frontend_closed(xbdev);
1309 return;
1310 }
1311
1312 mutex_lock(&bdev->bd_mutex);
1313
1314 if (bdev->bd_openers) {
1315 xenbus_dev_error(xbdev, -EBUSY,
1316 "Device in use; refusing to close");
1317 xenbus_switch_state(xbdev, XenbusStateClosing);
1318 } else {
1319 xlvbd_release_gendisk(info);
1320 xenbus_frontend_closed(xbdev);
1321 }
1322
1323 mutex_unlock(&bdev->bd_mutex);
1324 bdput(bdev);
1325 }
1326
1327 static void blkfront_setup_discard(struct blkfront_info *info)
1328 {
1329 int err;
1330 char *type;
1331 unsigned int discard_granularity;
1332 unsigned int discard_alignment;
1333 unsigned int discard_secure;
1334
1335 type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
1336 if (IS_ERR(type))
1337 return;
1338
1339 info->feature_secdiscard = 0;
1340 if (strncmp(type, "phy", 3) == 0) {
1341 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1342 "discard-granularity", "%u", &discard_granularity,
1343 "discard-alignment", "%u", &discard_alignment,
1344 NULL);
1345 if (!err) {
1346 info->feature_discard = 1;
1347 info->discard_granularity = discard_granularity;
1348 info->discard_alignment = discard_alignment;
1349 }
1350 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1351 "discard-secure", "%d", &discard_secure,
1352 NULL);
1353 if (!err)
1354 info->feature_secdiscard = discard_secure;
1355
1356 } else if (strncmp(type, "file", 4) == 0)
1357 info->feature_discard = 1;
1358
1359 kfree(type);
1360 }
1361
1362 /*
1363 * Invoked when the backend is finally 'ready' (and has told produced
1364 * the details about the physical device - #sectors, size, etc).
1365 */
1366 static void blkfront_connect(struct blkfront_info *info)
1367 {
1368 unsigned long long sectors;
1369 unsigned long sector_size;
1370 unsigned int binfo;
1371 int err;
1372 int barrier, flush, discard, persistent;
1373
1374 switch (info->connected) {
1375 case BLKIF_STATE_CONNECTED:
1376 /*
1377 * Potentially, the back-end may be signalling
1378 * a capacity change; update the capacity.
1379 */
1380 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1381 "sectors", "%Lu", &sectors);
1382 if (XENBUS_EXIST_ERR(err))
1383 return;
1384 printk(KERN_INFO "Setting capacity to %Lu\n",
1385 sectors);
1386 set_capacity(info->gd, sectors);
1387 revalidate_disk(info->gd);
1388
1389 /* fall through */
1390 case BLKIF_STATE_SUSPENDED:
1391 return;
1392
1393 default:
1394 break;
1395 }
1396
1397 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1398 __func__, info->xbdev->otherend);
1399
1400 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1401 "sectors", "%llu", &sectors,
1402 "info", "%u", &binfo,
1403 "sector-size", "%lu", &sector_size,
1404 NULL);
1405 if (err) {
1406 xenbus_dev_fatal(info->xbdev, err,
1407 "reading backend fields at %s",
1408 info->xbdev->otherend);
1409 return;
1410 }
1411
1412 info->feature_flush = 0;
1413 info->flush_op = 0;
1414
1415 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1416 "feature-barrier", "%d", &barrier,
1417 NULL);
1418
1419 /*
1420 * If there's no "feature-barrier" defined, then it means
1421 * we're dealing with a very old backend which writes
1422 * synchronously; nothing to do.
1423 *
1424 * If there are barriers, then we use flush.
1425 */
1426 if (!err && barrier) {
1427 info->feature_flush = REQ_FLUSH | REQ_FUA;
1428 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1429 }
1430 /*
1431 * And if there is "feature-flush-cache" use that above
1432 * barriers.
1433 */
1434 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1435 "feature-flush-cache", "%d", &flush,
1436 NULL);
1437
1438 if (!err && flush) {
1439 info->feature_flush = REQ_FLUSH;
1440 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1441 }
1442
1443 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1444 "feature-discard", "%d", &discard,
1445 NULL);
1446
1447 if (!err && discard)
1448 blkfront_setup_discard(info);
1449
1450 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1451 "feature-persistent", "%u", &persistent,
1452 NULL);
1453 if (err)
1454 info->feature_persistent = 0;
1455 else
1456 info->feature_persistent = persistent;
1457
1458 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1459 if (err) {
1460 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1461 info->xbdev->otherend);
1462 return;
1463 }
1464
1465 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1466
1467 /* Kick pending requests. */
1468 spin_lock_irq(&info->io_lock);
1469 info->connected = BLKIF_STATE_CONNECTED;
1470 kick_pending_request_queues(info);
1471 spin_unlock_irq(&info->io_lock);
1472
1473 add_disk(info->gd);
1474
1475 info->is_ready = 1;
1476 }
1477
1478 /**
1479 * Callback received when the backend's state changes.
1480 */
1481 static void blkback_changed(struct xenbus_device *dev,
1482 enum xenbus_state backend_state)
1483 {
1484 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1485
1486 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1487
1488 switch (backend_state) {
1489 case XenbusStateInitialising:
1490 case XenbusStateInitWait:
1491 case XenbusStateInitialised:
1492 case XenbusStateReconfiguring:
1493 case XenbusStateReconfigured:
1494 case XenbusStateUnknown:
1495 case XenbusStateClosed:
1496 break;
1497
1498 case XenbusStateConnected:
1499 blkfront_connect(info);
1500 break;
1501
1502 case XenbusStateClosing:
1503 blkfront_closing(info);
1504 break;
1505 }
1506 }
1507
1508 static int blkfront_remove(struct xenbus_device *xbdev)
1509 {
1510 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1511 struct block_device *bdev = NULL;
1512 struct gendisk *disk;
1513
1514 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1515
1516 blkif_free(info, 0);
1517
1518 mutex_lock(&info->mutex);
1519
1520 disk = info->gd;
1521 if (disk)
1522 bdev = bdget_disk(disk, 0);
1523
1524 info->xbdev = NULL;
1525 mutex_unlock(&info->mutex);
1526
1527 if (!bdev) {
1528 kfree(info);
1529 return 0;
1530 }
1531
1532 /*
1533 * The xbdev was removed before we reached the Closed
1534 * state. See if it's safe to remove the disk. If the bdev
1535 * isn't closed yet, we let release take care of it.
1536 */
1537
1538 mutex_lock(&bdev->bd_mutex);
1539 info = disk->private_data;
1540
1541 dev_warn(disk_to_dev(disk),
1542 "%s was hot-unplugged, %d stale handles\n",
1543 xbdev->nodename, bdev->bd_openers);
1544
1545 if (info && !bdev->bd_openers) {
1546 xlvbd_release_gendisk(info);
1547 disk->private_data = NULL;
1548 kfree(info);
1549 }
1550
1551 mutex_unlock(&bdev->bd_mutex);
1552 bdput(bdev);
1553
1554 return 0;
1555 }
1556
1557 static int blkfront_is_ready(struct xenbus_device *dev)
1558 {
1559 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1560
1561 return info->is_ready && info->xbdev;
1562 }
1563
1564 static int blkif_open(struct block_device *bdev, fmode_t mode)
1565 {
1566 struct gendisk *disk = bdev->bd_disk;
1567 struct blkfront_info *info;
1568 int err = 0;
1569
1570 mutex_lock(&blkfront_mutex);
1571
1572 info = disk->private_data;
1573 if (!info) {
1574 /* xbdev gone */
1575 err = -ERESTARTSYS;
1576 goto out;
1577 }
1578
1579 mutex_lock(&info->mutex);
1580
1581 if (!info->gd)
1582 /* xbdev is closed */
1583 err = -ERESTARTSYS;
1584
1585 mutex_unlock(&info->mutex);
1586
1587 out:
1588 mutex_unlock(&blkfront_mutex);
1589 return err;
1590 }
1591
1592 static int blkif_release(struct gendisk *disk, fmode_t mode)
1593 {
1594 struct blkfront_info *info = disk->private_data;
1595 struct block_device *bdev;
1596 struct xenbus_device *xbdev;
1597
1598 mutex_lock(&blkfront_mutex);
1599
1600 bdev = bdget_disk(disk, 0);
1601
1602 if (bdev->bd_openers)
1603 goto out;
1604
1605 /*
1606 * Check if we have been instructed to close. We will have
1607 * deferred this request, because the bdev was still open.
1608 */
1609
1610 mutex_lock(&info->mutex);
1611 xbdev = info->xbdev;
1612
1613 if (xbdev && xbdev->state == XenbusStateClosing) {
1614 /* pending switch to state closed */
1615 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1616 xlvbd_release_gendisk(info);
1617 xenbus_frontend_closed(info->xbdev);
1618 }
1619
1620 mutex_unlock(&info->mutex);
1621
1622 if (!xbdev) {
1623 /* sudden device removal */
1624 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1625 xlvbd_release_gendisk(info);
1626 disk->private_data = NULL;
1627 kfree(info);
1628 }
1629
1630 out:
1631 bdput(bdev);
1632 mutex_unlock(&blkfront_mutex);
1633 return 0;
1634 }
1635
1636 static const struct block_device_operations xlvbd_block_fops =
1637 {
1638 .owner = THIS_MODULE,
1639 .open = blkif_open,
1640 .release = blkif_release,
1641 .getgeo = blkif_getgeo,
1642 .ioctl = blkif_ioctl,
1643 };
1644
1645
1646 static const struct xenbus_device_id blkfront_ids[] = {
1647 { "vbd" },
1648 { "" }
1649 };
1650
1651 static DEFINE_XENBUS_DRIVER(blkfront, ,
1652 .probe = blkfront_probe,
1653 .remove = blkfront_remove,
1654 .resume = blkfront_resume,
1655 .otherend_changed = blkback_changed,
1656 .is_ready = blkfront_is_ready,
1657 );
1658
1659 static int __init xlblk_init(void)
1660 {
1661 int ret;
1662
1663 if (!xen_domain())
1664 return -ENODEV;
1665
1666 if (xen_hvm_domain() && !xen_platform_pci_unplug)
1667 return -ENODEV;
1668
1669 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1670 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1671 XENVBD_MAJOR, DEV_NAME);
1672 return -ENODEV;
1673 }
1674
1675 ret = xenbus_register_frontend(&blkfront_driver);
1676 if (ret) {
1677 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
1678 return ret;
1679 }
1680
1681 return 0;
1682 }
1683 module_init(xlblk_init);
1684
1685
1686 static void __exit xlblk_exit(void)
1687 {
1688 xenbus_unregister_driver(&blkfront_driver);
1689 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
1690 kfree(minors);
1691 }
1692 module_exit(xlblk_exit);
1693
1694 MODULE_DESCRIPTION("Xen virtual block device frontend");
1695 MODULE_LICENSE("GPL");
1696 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1697 MODULE_ALIAS("xen:vbd");
1698 MODULE_ALIAS("xenblk");
Linux kernel - Deliverables
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