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
get_id_from_freelist(struct blkfront_info * info)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
add_id_to_freelist(struct blkfront_info * info,unsigned long id)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
fill_grant_buffer(struct blkfront_info * info,int num)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
get_grant(grant_ref_t * gref_head,unsigned long pfn,struct blkfront_info * info)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
op_name(int op)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 }
xlbd_reserve_minors(unsigned int minor,unsigned int nr)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
xlbd_release_minors(unsigned int minor,unsigned int nr)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
blkif_restart_queue_callback(void * arg)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
blkif_getgeo(struct block_device * bd,struct hd_geometry * hg)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
blkif_ioctl(struct block_device * bdev,fmode_t mode,unsigned command,unsigned long argument)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 */
blkif_queue_request(struct request * req)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
flush_requests(struct blkfront_info * info)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
blkif_request_flush_valid(struct request * req,struct blkfront_info * info)585 static inline bool blkif_request_flush_valid(struct request *req,
586 struct blkfront_info *info)
587 {
588 return ((req->cmd_type != REQ_TYPE_FS) ||
589 ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) &&
590 !info->flush_op));
591 }
592
593 /*
594 * do_blkif_request
595 * read a block; request is in a request queue
596 */
do_blkif_request(struct request_queue * rq)597 static void do_blkif_request(struct request_queue *rq)
598 {
599 struct blkfront_info *info = NULL;
600 struct request *req;
601 int queued;
602
603 pr_debug("Entered do_blkif_request\n");
604
605 queued = 0;
606
607 while ((req = blk_peek_request(rq)) != NULL) {
608 info = req->rq_disk->private_data;
609
610 if (RING_FULL(&info->ring))
611 goto wait;
612
613 blk_start_request(req);
614
615 if (blkif_request_flush_valid(req, info)) {
616 __blk_end_request_all(req, -EIO);
617 continue;
618 }
619
620 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
621 "(%u/%u) [%s]\n",
622 req, req->cmd, (unsigned long)blk_rq_pos(req),
623 blk_rq_cur_sectors(req), blk_rq_sectors(req),
624 rq_data_dir(req) ? "write" : "read");
625
626 if (blkif_queue_request(req)) {
627 blk_requeue_request(rq, req);
628 wait:
629 /* Avoid pointless unplugs. */
630 blk_stop_queue(rq);
631 break;
632 }
633
634 queued++;
635 }
636
637 if (queued != 0)
638 flush_requests(info);
639 }
640
xlvbd_init_blk_queue(struct gendisk * gd,u16 sector_size,unsigned int physical_sector_size,unsigned int segments)641 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
642 unsigned int physical_sector_size,
643 unsigned int segments)
644 {
645 struct request_queue *rq;
646 struct blkfront_info *info = gd->private_data;
647
648 rq = blk_init_queue(do_blkif_request, &info->io_lock);
649 if (rq == NULL)
650 return -1;
651
652 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
653
654 if (info->feature_discard) {
655 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
656 blk_queue_max_discard_sectors(rq, get_capacity(gd));
657 rq->limits.discard_granularity = info->discard_granularity;
658 rq->limits.discard_alignment = info->discard_alignment;
659 if (info->feature_secdiscard)
660 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
661 }
662
663 /* Hard sector size and max sectors impersonate the equiv. hardware. */
664 blk_queue_logical_block_size(rq, sector_size);
665 blk_queue_physical_block_size(rq, physical_sector_size);
666 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512);
667
668 /* Each segment in a request is up to an aligned page in size. */
669 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
670 blk_queue_max_segment_size(rq, PAGE_SIZE);
671
672 /* Ensure a merged request will fit in a single I/O ring slot. */
673 blk_queue_max_segments(rq, segments);
674
675 /* Make sure buffer addresses are sector-aligned. */
676 blk_queue_dma_alignment(rq, 511);
677
678 /* Make sure we don't use bounce buffers. */
679 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
680
681 gd->queue = rq;
682
683 return 0;
684 }
685
686
xlvbd_flush(struct blkfront_info * info)687 static void xlvbd_flush(struct blkfront_info *info)
688 {
689 blk_queue_flush(info->rq, info->feature_flush);
690 printk(KERN_INFO "blkfront: %s: %s: %s %s %s %s %s\n",
691 info->gd->disk_name,
692 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
693 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
694 "flush diskcache" : "barrier or flush"),
695 info->feature_flush ? "enabled;" : "disabled;",
696 "persistent grants:",
697 info->feature_persistent ? "enabled;" : "disabled;",
698 "indirect descriptors:",
699 info->max_indirect_segments ? "enabled;" : "disabled;");
700 }
701
xen_translate_vdev(int vdevice,int * minor,unsigned int * offset)702 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
703 {
704 int major;
705 major = BLKIF_MAJOR(vdevice);
706 *minor = BLKIF_MINOR(vdevice);
707 switch (major) {
708 case XEN_IDE0_MAJOR:
709 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
710 *minor = ((*minor / 64) * PARTS_PER_DISK) +
711 EMULATED_HD_DISK_MINOR_OFFSET;
712 break;
713 case XEN_IDE1_MAJOR:
714 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
715 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
716 EMULATED_HD_DISK_MINOR_OFFSET;
717 break;
718 case XEN_SCSI_DISK0_MAJOR:
719 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
720 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
721 break;
722 case XEN_SCSI_DISK1_MAJOR:
723 case XEN_SCSI_DISK2_MAJOR:
724 case XEN_SCSI_DISK3_MAJOR:
725 case XEN_SCSI_DISK4_MAJOR:
726 case XEN_SCSI_DISK5_MAJOR:
727 case XEN_SCSI_DISK6_MAJOR:
728 case XEN_SCSI_DISK7_MAJOR:
729 *offset = (*minor / PARTS_PER_DISK) +
730 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
731 EMULATED_SD_DISK_NAME_OFFSET;
732 *minor = *minor +
733 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
734 EMULATED_SD_DISK_MINOR_OFFSET;
735 break;
736 case XEN_SCSI_DISK8_MAJOR:
737 case XEN_SCSI_DISK9_MAJOR:
738 case XEN_SCSI_DISK10_MAJOR:
739 case XEN_SCSI_DISK11_MAJOR:
740 case XEN_SCSI_DISK12_MAJOR:
741 case XEN_SCSI_DISK13_MAJOR:
742 case XEN_SCSI_DISK14_MAJOR:
743 case XEN_SCSI_DISK15_MAJOR:
744 *offset = (*minor / PARTS_PER_DISK) +
745 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
746 EMULATED_SD_DISK_NAME_OFFSET;
747 *minor = *minor +
748 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
749 EMULATED_SD_DISK_MINOR_OFFSET;
750 break;
751 case XENVBD_MAJOR:
752 *offset = *minor / PARTS_PER_DISK;
753 break;
754 default:
755 printk(KERN_WARNING "blkfront: your disk configuration is "
756 "incorrect, please use an xvd device instead\n");
757 return -ENODEV;
758 }
759 return 0;
760 }
761
encode_disk_name(char * ptr,unsigned int n)762 static char *encode_disk_name(char *ptr, unsigned int n)
763 {
764 if (n >= 26)
765 ptr = encode_disk_name(ptr, n / 26 - 1);
766 *ptr = 'a' + n % 26;
767 return ptr + 1;
768 }
769
xlvbd_alloc_gendisk(blkif_sector_t capacity,struct blkfront_info * info,u16 vdisk_info,u16 sector_size,unsigned int physical_sector_size)770 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
771 struct blkfront_info *info,
772 u16 vdisk_info, u16 sector_size,
773 unsigned int physical_sector_size)
774 {
775 struct gendisk *gd;
776 int nr_minors = 1;
777 int err;
778 unsigned int offset;
779 int minor;
780 int nr_parts;
781 char *ptr;
782
783 BUG_ON(info->gd != NULL);
784 BUG_ON(info->rq != NULL);
785
786 if ((info->vdevice>>EXT_SHIFT) > 1) {
787 /* this is above the extended range; something is wrong */
788 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
789 return -ENODEV;
790 }
791
792 if (!VDEV_IS_EXTENDED(info->vdevice)) {
793 err = xen_translate_vdev(info->vdevice, &minor, &offset);
794 if (err)
795 return err;
796 nr_parts = PARTS_PER_DISK;
797 } else {
798 minor = BLKIF_MINOR_EXT(info->vdevice);
799 nr_parts = PARTS_PER_EXT_DISK;
800 offset = minor / nr_parts;
801 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
802 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
803 "emulated IDE disks,\n\t choose an xvd device name"
804 "from xvde on\n", info->vdevice);
805 }
806 if (minor >> MINORBITS) {
807 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
808 info->vdevice, minor);
809 return -ENODEV;
810 }
811
812 if ((minor % nr_parts) == 0)
813 nr_minors = nr_parts;
814
815 err = xlbd_reserve_minors(minor, nr_minors);
816 if (err)
817 goto out;
818 err = -ENODEV;
819
820 gd = alloc_disk(nr_minors);
821 if (gd == NULL)
822 goto release;
823
824 strcpy(gd->disk_name, DEV_NAME);
825 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
826 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
827 if (nr_minors > 1)
828 *ptr = 0;
829 else
830 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
831 "%d", minor & (nr_parts - 1));
832
833 gd->major = XENVBD_MAJOR;
834 gd->first_minor = minor;
835 gd->fops = &xlvbd_block_fops;
836 gd->private_data = info;
837 gd->driverfs_dev = &(info->xbdev->dev);
838 set_capacity(gd, capacity);
839
840 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
841 info->max_indirect_segments ? :
842 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
843 del_gendisk(gd);
844 goto release;
845 }
846
847 info->rq = gd->queue;
848 info->gd = gd;
849
850 xlvbd_flush(info);
851
852 if (vdisk_info & VDISK_READONLY)
853 set_disk_ro(gd, 1);
854
855 if (vdisk_info & VDISK_REMOVABLE)
856 gd->flags |= GENHD_FL_REMOVABLE;
857
858 if (vdisk_info & VDISK_CDROM)
859 gd->flags |= GENHD_FL_CD;
860
861 return 0;
862
863 release:
864 xlbd_release_minors(minor, nr_minors);
865 out:
866 return err;
867 }
868
xlvbd_release_gendisk(struct blkfront_info * info)869 static void xlvbd_release_gendisk(struct blkfront_info *info)
870 {
871 unsigned int minor, nr_minors;
872 unsigned long flags;
873
874 if (info->rq == NULL)
875 return;
876
877 spin_lock_irqsave(&info->io_lock, flags);
878
879 /* No more blkif_request(). */
880 blk_stop_queue(info->rq);
881
882 /* No more gnttab callback work. */
883 gnttab_cancel_free_callback(&info->callback);
884 spin_unlock_irqrestore(&info->io_lock, flags);
885
886 /* Flush gnttab callback work. Must be done with no locks held. */
887 flush_work(&info->work);
888
889 del_gendisk(info->gd);
890
891 minor = info->gd->first_minor;
892 nr_minors = info->gd->minors;
893 xlbd_release_minors(minor, nr_minors);
894
895 blk_cleanup_queue(info->rq);
896 info->rq = NULL;
897
898 put_disk(info->gd);
899 info->gd = NULL;
900 }
901
kick_pending_request_queues(struct blkfront_info * info)902 static void kick_pending_request_queues(struct blkfront_info *info)
903 {
904 if (!RING_FULL(&info->ring)) {
905 /* Re-enable calldowns. */
906 blk_start_queue(info->rq);
907 /* Kick things off immediately. */
908 do_blkif_request(info->rq);
909 }
910 }
911
blkif_restart_queue(struct work_struct * work)912 static void blkif_restart_queue(struct work_struct *work)
913 {
914 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
915
916 spin_lock_irq(&info->io_lock);
917 if (info->connected == BLKIF_STATE_CONNECTED)
918 kick_pending_request_queues(info);
919 spin_unlock_irq(&info->io_lock);
920 }
921
blkif_free(struct blkfront_info * info,int suspend)922 static void blkif_free(struct blkfront_info *info, int suspend)
923 {
924 struct grant *persistent_gnt;
925 struct grant *n;
926 int i, j, segs;
927
928 /* Prevent new requests being issued until we fix things up. */
929 spin_lock_irq(&info->io_lock);
930 info->connected = suspend ?
931 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
932 /* No more blkif_request(). */
933 if (info->rq)
934 blk_stop_queue(info->rq);
935
936 /* Remove all persistent grants */
937 if (!list_empty(&info->grants)) {
938 list_for_each_entry_safe(persistent_gnt, n,
939 &info->grants, node) {
940 list_del(&persistent_gnt->node);
941 if (persistent_gnt->gref != GRANT_INVALID_REF) {
942 gnttab_end_foreign_access(persistent_gnt->gref,
943 0, 0UL);
944 info->persistent_gnts_c--;
945 }
946 if (info->feature_persistent)
947 __free_page(pfn_to_page(persistent_gnt->pfn));
948 kfree(persistent_gnt);
949 }
950 }
951 BUG_ON(info->persistent_gnts_c != 0);
952
953 /*
954 * Remove indirect pages, this only happens when using indirect
955 * descriptors but not persistent grants
956 */
957 if (!list_empty(&info->indirect_pages)) {
958 struct page *indirect_page, *n;
959
960 BUG_ON(info->feature_persistent);
961 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
962 list_del(&indirect_page->lru);
963 __free_page(indirect_page);
964 }
965 }
966
967 for (i = 0; i < BLK_RING_SIZE; i++) {
968 /*
969 * Clear persistent grants present in requests already
970 * on the shared ring
971 */
972 if (!info->shadow[i].request)
973 goto free_shadow;
974
975 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
976 info->shadow[i].req.u.indirect.nr_segments :
977 info->shadow[i].req.u.rw.nr_segments;
978 for (j = 0; j < segs; j++) {
979 persistent_gnt = info->shadow[i].grants_used[j];
980 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
981 if (info->feature_persistent)
982 __free_page(pfn_to_page(persistent_gnt->pfn));
983 kfree(persistent_gnt);
984 }
985
986 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT)
987 /*
988 * If this is not an indirect operation don't try to
989 * free indirect segments
990 */
991 goto free_shadow;
992
993 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
994 persistent_gnt = info->shadow[i].indirect_grants[j];
995 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
996 __free_page(pfn_to_page(persistent_gnt->pfn));
997 kfree(persistent_gnt);
998 }
999
1000 free_shadow:
1001 kfree(info->shadow[i].grants_used);
1002 info->shadow[i].grants_used = NULL;
1003 kfree(info->shadow[i].indirect_grants);
1004 info->shadow[i].indirect_grants = NULL;
1005 kfree(info->shadow[i].sg);
1006 info->shadow[i].sg = NULL;
1007 }
1008
1009 /* No more gnttab callback work. */
1010 gnttab_cancel_free_callback(&info->callback);
1011 spin_unlock_irq(&info->io_lock);
1012
1013 /* Flush gnttab callback work. Must be done with no locks held. */
1014 flush_work(&info->work);
1015
1016 /* Free resources associated with old device channel. */
1017 if (info->ring_ref != GRANT_INVALID_REF) {
1018 gnttab_end_foreign_access(info->ring_ref, 0,
1019 (unsigned long)info->ring.sring);
1020 info->ring_ref = GRANT_INVALID_REF;
1021 info->ring.sring = NULL;
1022 }
1023 if (info->irq)
1024 unbind_from_irqhandler(info->irq, info);
1025 info->evtchn = info->irq = 0;
1026
1027 }
1028
blkif_completion(struct blk_shadow * s,struct blkfront_info * info,struct blkif_response * bret)1029 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
1030 struct blkif_response *bret)
1031 {
1032 int i = 0;
1033 struct scatterlist *sg;
1034 char *bvec_data;
1035 void *shared_data;
1036 int nseg;
1037
1038 nseg = s->req.operation == BLKIF_OP_INDIRECT ?
1039 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1040
1041 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1042 /*
1043 * Copy the data received from the backend into the bvec.
1044 * Since bv_offset can be different than 0, and bv_len different
1045 * than PAGE_SIZE, we have to keep track of the current offset,
1046 * to be sure we are copying the data from the right shared page.
1047 */
1048 for_each_sg(s->sg, sg, nseg, i) {
1049 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1050 shared_data = kmap_atomic(
1051 pfn_to_page(s->grants_used[i]->pfn));
1052 bvec_data = kmap_atomic(sg_page(sg));
1053 memcpy(bvec_data + sg->offset,
1054 shared_data + sg->offset,
1055 sg->length);
1056 kunmap_atomic(bvec_data);
1057 kunmap_atomic(shared_data);
1058 }
1059 }
1060 /* Add the persistent grant into the list of free grants */
1061 for (i = 0; i < nseg; i++) {
1062 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1063 /*
1064 * If the grant is still mapped by the backend (the
1065 * backend has chosen to make this grant persistent)
1066 * we add it at the head of the list, so it will be
1067 * reused first.
1068 */
1069 if (!info->feature_persistent)
1070 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1071 s->grants_used[i]->gref);
1072 list_add(&s->grants_used[i]->node, &info->grants);
1073 info->persistent_gnts_c++;
1074 } else {
1075 /*
1076 * If the grant is not mapped by the backend we end the
1077 * foreign access and add it to the tail of the list,
1078 * so it will not be picked again unless we run out of
1079 * persistent grants.
1080 */
1081 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1082 s->grants_used[i]->gref = GRANT_INVALID_REF;
1083 list_add_tail(&s->grants_used[i]->node, &info->grants);
1084 }
1085 }
1086 if (s->req.operation == BLKIF_OP_INDIRECT) {
1087 for (i = 0; i < INDIRECT_GREFS(nseg); i++) {
1088 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1089 if (!info->feature_persistent)
1090 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1091 s->indirect_grants[i]->gref);
1092 list_add(&s->indirect_grants[i]->node, &info->grants);
1093 info->persistent_gnts_c++;
1094 } else {
1095 struct page *indirect_page;
1096
1097 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1098 /*
1099 * Add the used indirect page back to the list of
1100 * available pages for indirect grefs.
1101 */
1102 if (!info->feature_persistent) {
1103 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
1104 list_add(&indirect_page->lru, &info->indirect_pages);
1105 }
1106 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1107 list_add_tail(&s->indirect_grants[i]->node, &info->grants);
1108 }
1109 }
1110 }
1111 }
1112
blkif_interrupt(int irq,void * dev_id)1113 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1114 {
1115 struct request *req;
1116 struct blkif_response *bret;
1117 RING_IDX i, rp;
1118 unsigned long flags;
1119 struct blkfront_info *info = (struct blkfront_info *)dev_id;
1120 int error;
1121
1122 spin_lock_irqsave(&info->io_lock, flags);
1123
1124 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1125 spin_unlock_irqrestore(&info->io_lock, flags);
1126 return IRQ_HANDLED;
1127 }
1128
1129 again:
1130 rp = info->ring.sring->rsp_prod;
1131 rmb(); /* Ensure we see queued responses up to 'rp'. */
1132
1133 for (i = info->ring.rsp_cons; i != rp; i++) {
1134 unsigned long id;
1135
1136 bret = RING_GET_RESPONSE(&info->ring, i);
1137 id = bret->id;
1138 /*
1139 * The backend has messed up and given us an id that we would
1140 * never have given to it (we stamp it up to BLK_RING_SIZE -
1141 * look in get_id_from_freelist.
1142 */
1143 if (id >= BLK_RING_SIZE) {
1144 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1145 info->gd->disk_name, op_name(bret->operation), id);
1146 /* We can't safely get the 'struct request' as
1147 * the id is busted. */
1148 continue;
1149 }
1150 req = info->shadow[id].request;
1151
1152 if (bret->operation != BLKIF_OP_DISCARD)
1153 blkif_completion(&info->shadow[id], info, bret);
1154
1155 if (add_id_to_freelist(info, id)) {
1156 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1157 info->gd->disk_name, op_name(bret->operation), id);
1158 continue;
1159 }
1160
1161 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1162 switch (bret->operation) {
1163 case BLKIF_OP_DISCARD:
1164 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1165 struct request_queue *rq = info->rq;
1166 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1167 info->gd->disk_name, op_name(bret->operation));
1168 error = -EOPNOTSUPP;
1169 info->feature_discard = 0;
1170 info->feature_secdiscard = 0;
1171 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1172 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1173 }
1174 __blk_end_request_all(req, error);
1175 break;
1176 case BLKIF_OP_FLUSH_DISKCACHE:
1177 case BLKIF_OP_WRITE_BARRIER:
1178 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1179 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1180 info->gd->disk_name, op_name(bret->operation));
1181 error = -EOPNOTSUPP;
1182 }
1183 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1184 info->shadow[id].req.u.rw.nr_segments == 0)) {
1185 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1186 info->gd->disk_name, op_name(bret->operation));
1187 error = -EOPNOTSUPP;
1188 }
1189 if (unlikely(error)) {
1190 if (error == -EOPNOTSUPP)
1191 error = 0;
1192 info->feature_flush = 0;
1193 info->flush_op = 0;
1194 xlvbd_flush(info);
1195 }
1196 /* fall through */
1197 case BLKIF_OP_READ:
1198 case BLKIF_OP_WRITE:
1199 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1200 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1201 "request: %x\n", bret->status);
1202
1203 __blk_end_request_all(req, error);
1204 break;
1205 default:
1206 BUG();
1207 }
1208 }
1209
1210 info->ring.rsp_cons = i;
1211
1212 if (i != info->ring.req_prod_pvt) {
1213 int more_to_do;
1214 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
1215 if (more_to_do)
1216 goto again;
1217 } else
1218 info->ring.sring->rsp_event = i + 1;
1219
1220 kick_pending_request_queues(info);
1221
1222 spin_unlock_irqrestore(&info->io_lock, flags);
1223
1224 return IRQ_HANDLED;
1225 }
1226
1227
setup_blkring(struct xenbus_device * dev,struct blkfront_info * info)1228 static int setup_blkring(struct xenbus_device *dev,
1229 struct blkfront_info *info)
1230 {
1231 struct blkif_sring *sring;
1232 int err;
1233
1234 info->ring_ref = GRANT_INVALID_REF;
1235
1236 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
1237 if (!sring) {
1238 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1239 return -ENOMEM;
1240 }
1241 SHARED_RING_INIT(sring);
1242 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
1243
1244 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
1245 if (err < 0) {
1246 free_page((unsigned long)sring);
1247 info->ring.sring = NULL;
1248 goto fail;
1249 }
1250 info->ring_ref = err;
1251
1252 err = xenbus_alloc_evtchn(dev, &info->evtchn);
1253 if (err)
1254 goto fail;
1255
1256 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
1257 "blkif", info);
1258 if (err <= 0) {
1259 xenbus_dev_fatal(dev, err,
1260 "bind_evtchn_to_irqhandler failed");
1261 goto fail;
1262 }
1263 info->irq = err;
1264
1265 return 0;
1266 fail:
1267 blkif_free(info, 0);
1268 return err;
1269 }
1270
1271
1272 /* Common code used when first setting up, and when resuming. */
talk_to_blkback(struct xenbus_device * dev,struct blkfront_info * info)1273 static int talk_to_blkback(struct xenbus_device *dev,
1274 struct blkfront_info *info)
1275 {
1276 const char *message = NULL;
1277 struct xenbus_transaction xbt;
1278 int err;
1279
1280 /* Create shared ring, alloc event channel. */
1281 err = setup_blkring(dev, info);
1282 if (err)
1283 goto out;
1284
1285 again:
1286 err = xenbus_transaction_start(&xbt);
1287 if (err) {
1288 xenbus_dev_fatal(dev, err, "starting transaction");
1289 goto destroy_blkring;
1290 }
1291
1292 err = xenbus_printf(xbt, dev->nodename,
1293 "ring-ref", "%u", info->ring_ref);
1294 if (err) {
1295 message = "writing ring-ref";
1296 goto abort_transaction;
1297 }
1298 err = xenbus_printf(xbt, dev->nodename,
1299 "event-channel", "%u", info->evtchn);
1300 if (err) {
1301 message = "writing event-channel";
1302 goto abort_transaction;
1303 }
1304 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1305 XEN_IO_PROTO_ABI_NATIVE);
1306 if (err) {
1307 message = "writing protocol";
1308 goto abort_transaction;
1309 }
1310 err = xenbus_printf(xbt, dev->nodename,
1311 "feature-persistent", "%u", 1);
1312 if (err)
1313 dev_warn(&dev->dev,
1314 "writing persistent grants feature to xenbus");
1315
1316 err = xenbus_transaction_end(xbt, 0);
1317 if (err) {
1318 if (err == -EAGAIN)
1319 goto again;
1320 xenbus_dev_fatal(dev, err, "completing transaction");
1321 goto destroy_blkring;
1322 }
1323
1324 xenbus_switch_state(dev, XenbusStateInitialised);
1325
1326 return 0;
1327
1328 abort_transaction:
1329 xenbus_transaction_end(xbt, 1);
1330 if (message)
1331 xenbus_dev_fatal(dev, err, "%s", message);
1332 destroy_blkring:
1333 blkif_free(info, 0);
1334 out:
1335 return err;
1336 }
1337
1338 /**
1339 * Entry point to this code when a new device is created. Allocate the basic
1340 * structures and the ring buffer for communication with the backend, and
1341 * inform the backend of the appropriate details for those. Switch to
1342 * Initialised state.
1343 */
blkfront_probe(struct xenbus_device * dev,const struct xenbus_device_id * id)1344 static int blkfront_probe(struct xenbus_device *dev,
1345 const struct xenbus_device_id *id)
1346 {
1347 int err, vdevice, i;
1348 struct blkfront_info *info;
1349
1350 /* FIXME: Use dynamic device id if this is not set. */
1351 err = xenbus_scanf(XBT_NIL, dev->nodename,
1352 "virtual-device", "%i", &vdevice);
1353 if (err != 1) {
1354 /* go looking in the extended area instead */
1355 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1356 "%i", &vdevice);
1357 if (err != 1) {
1358 xenbus_dev_fatal(dev, err, "reading virtual-device");
1359 return err;
1360 }
1361 }
1362
1363 if (xen_hvm_domain()) {
1364 char *type;
1365 int len;
1366 /* no unplug has been done: do not hook devices != xen vbds */
1367 if (xen_has_pv_and_legacy_disk_devices()) {
1368 int major;
1369
1370 if (!VDEV_IS_EXTENDED(vdevice))
1371 major = BLKIF_MAJOR(vdevice);
1372 else
1373 major = XENVBD_MAJOR;
1374
1375 if (major != XENVBD_MAJOR) {
1376 printk(KERN_INFO
1377 "%s: HVM does not support vbd %d as xen block device\n",
1378 __FUNCTION__, vdevice);
1379 return -ENODEV;
1380 }
1381 }
1382 /* do not create a PV cdrom device if we are an HVM guest */
1383 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1384 if (IS_ERR(type))
1385 return -ENODEV;
1386 if (strncmp(type, "cdrom", 5) == 0) {
1387 kfree(type);
1388 return -ENODEV;
1389 }
1390 kfree(type);
1391 }
1392 info = kzalloc(sizeof(*info), GFP_KERNEL);
1393 if (!info) {
1394 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1395 return -ENOMEM;
1396 }
1397
1398 mutex_init(&info->mutex);
1399 spin_lock_init(&info->io_lock);
1400 info->xbdev = dev;
1401 info->vdevice = vdevice;
1402 INIT_LIST_HEAD(&info->grants);
1403 INIT_LIST_HEAD(&info->indirect_pages);
1404 info->persistent_gnts_c = 0;
1405 info->connected = BLKIF_STATE_DISCONNECTED;
1406 INIT_WORK(&info->work, blkif_restart_queue);
1407
1408 for (i = 0; i < BLK_RING_SIZE; i++)
1409 info->shadow[i].req.u.rw.id = i+1;
1410 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1411
1412 /* Front end dir is a number, which is used as the id. */
1413 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1414 dev_set_drvdata(&dev->dev, info);
1415
1416 err = talk_to_blkback(dev, info);
1417 if (err) {
1418 kfree(info);
1419 dev_set_drvdata(&dev->dev, NULL);
1420 return err;
1421 }
1422
1423 return 0;
1424 }
1425
split_bio_end(struct bio * bio,int error)1426 static void split_bio_end(struct bio *bio, int error)
1427 {
1428 struct split_bio *split_bio = bio->bi_private;
1429
1430 if (error)
1431 split_bio->err = error;
1432
1433 if (atomic_dec_and_test(&split_bio->pending)) {
1434 split_bio->bio->bi_phys_segments = 0;
1435 bio_endio(split_bio->bio, split_bio->err);
1436 kfree(split_bio);
1437 }
1438 bio_put(bio);
1439 }
1440
blkif_recover(struct blkfront_info * info)1441 static int blkif_recover(struct blkfront_info *info)
1442 {
1443 int i;
1444 struct request *req, *n;
1445 struct blk_shadow *copy;
1446 int rc;
1447 struct bio *bio, *cloned_bio;
1448 struct bio_list bio_list, merge_bio;
1449 unsigned int segs, offset;
1450 int pending, size;
1451 struct split_bio *split_bio;
1452 struct list_head requests;
1453
1454 /* Stage 1: Make a safe copy of the shadow state. */
1455 copy = kmemdup(info->shadow, sizeof(info->shadow),
1456 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1457 if (!copy)
1458 return -ENOMEM;
1459
1460 /* Stage 2: Set up free list. */
1461 memset(&info->shadow, 0, sizeof(info->shadow));
1462 for (i = 0; i < BLK_RING_SIZE; i++)
1463 info->shadow[i].req.u.rw.id = i+1;
1464 info->shadow_free = info->ring.req_prod_pvt;
1465 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1466
1467 rc = blkfront_setup_indirect(info);
1468 if (rc) {
1469 kfree(copy);
1470 return rc;
1471 }
1472
1473 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
1474 blk_queue_max_segments(info->rq, segs);
1475 bio_list_init(&bio_list);
1476 INIT_LIST_HEAD(&requests);
1477 for (i = 0; i < BLK_RING_SIZE; i++) {
1478 /* Not in use? */
1479 if (!copy[i].request)
1480 continue;
1481
1482 /*
1483 * Get the bios in the request so we can re-queue them.
1484 */
1485 if (copy[i].request->cmd_flags &
1486 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1487 /*
1488 * Flush operations don't contain bios, so
1489 * we need to requeue the whole request
1490 */
1491 list_add(©[i].request->queuelist, &requests);
1492 continue;
1493 }
1494 merge_bio.head = copy[i].request->bio;
1495 merge_bio.tail = copy[i].request->biotail;
1496 bio_list_merge(&bio_list, &merge_bio);
1497 copy[i].request->bio = NULL;
1498 blk_put_request(copy[i].request);
1499 }
1500
1501 kfree(copy);
1502
1503 /*
1504 * Empty the queue, this is important because we might have
1505 * requests in the queue with more segments than what we
1506 * can handle now.
1507 */
1508 spin_lock_irq(&info->io_lock);
1509 while ((req = blk_fetch_request(info->rq)) != NULL) {
1510 if (req->cmd_flags &
1511 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1512 list_add(&req->queuelist, &requests);
1513 continue;
1514 }
1515 merge_bio.head = req->bio;
1516 merge_bio.tail = req->biotail;
1517 bio_list_merge(&bio_list, &merge_bio);
1518 req->bio = NULL;
1519 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA))
1520 pr_alert("diskcache flush request found!\n");
1521 __blk_put_request(info->rq, req);
1522 }
1523 spin_unlock_irq(&info->io_lock);
1524
1525 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1526
1527 spin_lock_irq(&info->io_lock);
1528
1529 /* Now safe for us to use the shared ring */
1530 info->connected = BLKIF_STATE_CONNECTED;
1531
1532 /* Kick any other new requests queued since we resumed */
1533 kick_pending_request_queues(info);
1534
1535 list_for_each_entry_safe(req, n, &requests, queuelist) {
1536 /* Requeue pending requests (flush or discard) */
1537 list_del_init(&req->queuelist);
1538 BUG_ON(req->nr_phys_segments > segs);
1539 blk_requeue_request(info->rq, req);
1540 }
1541 spin_unlock_irq(&info->io_lock);
1542
1543 while ((bio = bio_list_pop(&bio_list)) != NULL) {
1544 /* Traverse the list of pending bios and re-queue them */
1545 if (bio_segments(bio) > segs) {
1546 /*
1547 * This bio has more segments than what we can
1548 * handle, we have to split it.
1549 */
1550 pending = (bio_segments(bio) + segs - 1) / segs;
1551 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
1552 BUG_ON(split_bio == NULL);
1553 atomic_set(&split_bio->pending, pending);
1554 split_bio->bio = bio;
1555 for (i = 0; i < pending; i++) {
1556 offset = (i * segs * PAGE_SIZE) >> 9;
1557 size = min((unsigned int)(segs * PAGE_SIZE) >> 9,
1558 (unsigned int)bio_sectors(bio) - offset);
1559 cloned_bio = bio_clone(bio, GFP_NOIO);
1560 BUG_ON(cloned_bio == NULL);
1561 bio_trim(cloned_bio, offset, size);
1562 cloned_bio->bi_private = split_bio;
1563 cloned_bio->bi_end_io = split_bio_end;
1564 submit_bio(cloned_bio->bi_rw, cloned_bio);
1565 }
1566 /*
1567 * Now we have to wait for all those smaller bios to
1568 * end, so we can also end the "parent" bio.
1569 */
1570 continue;
1571 }
1572 /* We don't need to split this bio */
1573 submit_bio(bio->bi_rw, bio);
1574 }
1575
1576 return 0;
1577 }
1578
1579 /**
1580 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1581 * driver restart. We tear down our blkif structure and recreate it, but
1582 * leave the device-layer structures intact so that this is transparent to the
1583 * rest of the kernel.
1584 */
blkfront_resume(struct xenbus_device * dev)1585 static int blkfront_resume(struct xenbus_device *dev)
1586 {
1587 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1588 int err;
1589
1590 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1591
1592 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1593
1594 err = talk_to_blkback(dev, info);
1595
1596 /*
1597 * We have to wait for the backend to switch to
1598 * connected state, since we want to read which
1599 * features it supports.
1600 */
1601
1602 return err;
1603 }
1604
1605 static void
blkfront_closing(struct blkfront_info * info)1606 blkfront_closing(struct blkfront_info *info)
1607 {
1608 struct xenbus_device *xbdev = info->xbdev;
1609 struct block_device *bdev = NULL;
1610
1611 mutex_lock(&info->mutex);
1612
1613 if (xbdev->state == XenbusStateClosing) {
1614 mutex_unlock(&info->mutex);
1615 return;
1616 }
1617
1618 if (info->gd)
1619 bdev = bdget_disk(info->gd, 0);
1620
1621 mutex_unlock(&info->mutex);
1622
1623 if (!bdev) {
1624 xenbus_frontend_closed(xbdev);
1625 return;
1626 }
1627
1628 mutex_lock(&bdev->bd_mutex);
1629
1630 if (bdev->bd_openers) {
1631 xenbus_dev_error(xbdev, -EBUSY,
1632 "Device in use; refusing to close");
1633 xenbus_switch_state(xbdev, XenbusStateClosing);
1634 } else {
1635 xlvbd_release_gendisk(info);
1636 xenbus_frontend_closed(xbdev);
1637 }
1638
1639 mutex_unlock(&bdev->bd_mutex);
1640 bdput(bdev);
1641 }
1642
blkfront_setup_discard(struct blkfront_info * info)1643 static void blkfront_setup_discard(struct blkfront_info *info)
1644 {
1645 int err;
1646 unsigned int discard_granularity;
1647 unsigned int discard_alignment;
1648 unsigned int discard_secure;
1649
1650 info->feature_discard = 1;
1651 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1652 "discard-granularity", "%u", &discard_granularity,
1653 "discard-alignment", "%u", &discard_alignment,
1654 NULL);
1655 if (!err) {
1656 info->discard_granularity = discard_granularity;
1657 info->discard_alignment = discard_alignment;
1658 }
1659 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1660 "discard-secure", "%d", &discard_secure,
1661 NULL);
1662 if (!err)
1663 info->feature_secdiscard = !!discard_secure;
1664 }
1665
blkfront_setup_indirect(struct blkfront_info * info)1666 static int blkfront_setup_indirect(struct blkfront_info *info)
1667 {
1668 unsigned int indirect_segments, segs;
1669 int err, i;
1670
1671 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1672 "feature-max-indirect-segments", "%u", &indirect_segments,
1673 NULL);
1674 if (err) {
1675 info->max_indirect_segments = 0;
1676 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
1677 } else {
1678 info->max_indirect_segments = min(indirect_segments,
1679 xen_blkif_max_segments);
1680 segs = info->max_indirect_segments;
1681 }
1682
1683 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE);
1684 if (err)
1685 goto out_of_memory;
1686
1687 if (!info->feature_persistent && info->max_indirect_segments) {
1688 /*
1689 * We are using indirect descriptors but not persistent
1690 * grants, we need to allocate a set of pages that can be
1691 * used for mapping indirect grefs
1692 */
1693 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE;
1694
1695 BUG_ON(!list_empty(&info->indirect_pages));
1696 for (i = 0; i < num; i++) {
1697 struct page *indirect_page = alloc_page(GFP_NOIO);
1698 if (!indirect_page)
1699 goto out_of_memory;
1700 list_add(&indirect_page->lru, &info->indirect_pages);
1701 }
1702 }
1703
1704 for (i = 0; i < BLK_RING_SIZE; i++) {
1705 info->shadow[i].grants_used = kzalloc(
1706 sizeof(info->shadow[i].grants_used[0]) * segs,
1707 GFP_NOIO);
1708 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO);
1709 if (info->max_indirect_segments)
1710 info->shadow[i].indirect_grants = kzalloc(
1711 sizeof(info->shadow[i].indirect_grants[0]) *
1712 INDIRECT_GREFS(segs),
1713 GFP_NOIO);
1714 if ((info->shadow[i].grants_used == NULL) ||
1715 (info->shadow[i].sg == NULL) ||
1716 (info->max_indirect_segments &&
1717 (info->shadow[i].indirect_grants == NULL)))
1718 goto out_of_memory;
1719 sg_init_table(info->shadow[i].sg, segs);
1720 }
1721
1722
1723 return 0;
1724
1725 out_of_memory:
1726 for (i = 0; i < BLK_RING_SIZE; i++) {
1727 kfree(info->shadow[i].grants_used);
1728 info->shadow[i].grants_used = NULL;
1729 kfree(info->shadow[i].sg);
1730 info->shadow[i].sg = NULL;
1731 kfree(info->shadow[i].indirect_grants);
1732 info->shadow[i].indirect_grants = NULL;
1733 }
1734 if (!list_empty(&info->indirect_pages)) {
1735 struct page *indirect_page, *n;
1736 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
1737 list_del(&indirect_page->lru);
1738 __free_page(indirect_page);
1739 }
1740 }
1741 return -ENOMEM;
1742 }
1743
1744 /*
1745 * Invoked when the backend is finally 'ready' (and has told produced
1746 * the details about the physical device - #sectors, size, etc).
1747 */
blkfront_connect(struct blkfront_info * info)1748 static void blkfront_connect(struct blkfront_info *info)
1749 {
1750 unsigned long long sectors;
1751 unsigned long sector_size;
1752 unsigned int physical_sector_size;
1753 unsigned int binfo;
1754 int err;
1755 int barrier, flush, discard, persistent;
1756
1757 switch (info->connected) {
1758 case BLKIF_STATE_CONNECTED:
1759 /*
1760 * Potentially, the back-end may be signalling
1761 * a capacity change; update the capacity.
1762 */
1763 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1764 "sectors", "%Lu", §ors);
1765 if (XENBUS_EXIST_ERR(err))
1766 return;
1767 printk(KERN_INFO "Setting capacity to %Lu\n",
1768 sectors);
1769 set_capacity(info->gd, sectors);
1770 revalidate_disk(info->gd);
1771
1772 return;
1773 case BLKIF_STATE_SUSPENDED:
1774 /*
1775 * If we are recovering from suspension, we need to wait
1776 * for the backend to announce it's features before
1777 * reconnecting, at least we need to know if the backend
1778 * supports indirect descriptors, and how many.
1779 */
1780 blkif_recover(info);
1781 return;
1782
1783 default:
1784 break;
1785 }
1786
1787 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1788 __func__, info->xbdev->otherend);
1789
1790 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1791 "sectors", "%llu", §ors,
1792 "info", "%u", &binfo,
1793 "sector-size", "%lu", §or_size,
1794 NULL);
1795 if (err) {
1796 xenbus_dev_fatal(info->xbdev, err,
1797 "reading backend fields at %s",
1798 info->xbdev->otherend);
1799 return;
1800 }
1801
1802 /*
1803 * physcial-sector-size is a newer field, so old backends may not
1804 * provide this. Assume physical sector size to be the same as
1805 * sector_size in that case.
1806 */
1807 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1808 "physical-sector-size", "%u", &physical_sector_size);
1809 if (err != 1)
1810 physical_sector_size = sector_size;
1811
1812 info->feature_flush = 0;
1813 info->flush_op = 0;
1814
1815 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1816 "feature-barrier", "%d", &barrier,
1817 NULL);
1818
1819 /*
1820 * If there's no "feature-barrier" defined, then it means
1821 * we're dealing with a very old backend which writes
1822 * synchronously; nothing to do.
1823 *
1824 * If there are barriers, then we use flush.
1825 */
1826 if (!err && barrier) {
1827 info->feature_flush = REQ_FLUSH | REQ_FUA;
1828 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1829 }
1830 /*
1831 * And if there is "feature-flush-cache" use that above
1832 * barriers.
1833 */
1834 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1835 "feature-flush-cache", "%d", &flush,
1836 NULL);
1837
1838 if (!err && flush) {
1839 info->feature_flush = REQ_FLUSH;
1840 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1841 }
1842
1843 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1844 "feature-discard", "%d", &discard,
1845 NULL);
1846
1847 if (!err && discard)
1848 blkfront_setup_discard(info);
1849
1850 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1851 "feature-persistent", "%u", &persistent,
1852 NULL);
1853 if (err)
1854 info->feature_persistent = 0;
1855 else
1856 info->feature_persistent = persistent;
1857
1858 err = blkfront_setup_indirect(info);
1859 if (err) {
1860 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
1861 info->xbdev->otherend);
1862 return;
1863 }
1864
1865 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
1866 physical_sector_size);
1867 if (err) {
1868 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1869 info->xbdev->otherend);
1870 return;
1871 }
1872
1873 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1874
1875 /* Kick pending requests. */
1876 spin_lock_irq(&info->io_lock);
1877 info->connected = BLKIF_STATE_CONNECTED;
1878 kick_pending_request_queues(info);
1879 spin_unlock_irq(&info->io_lock);
1880
1881 add_disk(info->gd);
1882
1883 info->is_ready = 1;
1884 }
1885
1886 /**
1887 * Callback received when the backend's state changes.
1888 */
blkback_changed(struct xenbus_device * dev,enum xenbus_state backend_state)1889 static void blkback_changed(struct xenbus_device *dev,
1890 enum xenbus_state backend_state)
1891 {
1892 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1893
1894 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1895
1896 switch (backend_state) {
1897 case XenbusStateInitialising:
1898 case XenbusStateInitWait:
1899 case XenbusStateInitialised:
1900 case XenbusStateReconfiguring:
1901 case XenbusStateReconfigured:
1902 case XenbusStateUnknown:
1903 break;
1904
1905 case XenbusStateConnected:
1906 blkfront_connect(info);
1907 break;
1908
1909 case XenbusStateClosed:
1910 if (dev->state == XenbusStateClosed)
1911 break;
1912 /* Missed the backend's Closing state -- fallthrough */
1913 case XenbusStateClosing:
1914 if (info)
1915 blkfront_closing(info);
1916 break;
1917 }
1918 }
1919
blkfront_remove(struct xenbus_device * xbdev)1920 static int blkfront_remove(struct xenbus_device *xbdev)
1921 {
1922 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1923 struct block_device *bdev = NULL;
1924 struct gendisk *disk;
1925
1926 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1927
1928 blkif_free(info, 0);
1929
1930 mutex_lock(&info->mutex);
1931
1932 disk = info->gd;
1933 if (disk)
1934 bdev = bdget_disk(disk, 0);
1935
1936 info->xbdev = NULL;
1937 mutex_unlock(&info->mutex);
1938
1939 if (!bdev) {
1940 kfree(info);
1941 return 0;
1942 }
1943
1944 /*
1945 * The xbdev was removed before we reached the Closed
1946 * state. See if it's safe to remove the disk. If the bdev
1947 * isn't closed yet, we let release take care of it.
1948 */
1949
1950 mutex_lock(&bdev->bd_mutex);
1951 info = disk->private_data;
1952
1953 dev_warn(disk_to_dev(disk),
1954 "%s was hot-unplugged, %d stale handles\n",
1955 xbdev->nodename, bdev->bd_openers);
1956
1957 if (info && !bdev->bd_openers) {
1958 xlvbd_release_gendisk(info);
1959 disk->private_data = NULL;
1960 kfree(info);
1961 }
1962
1963 mutex_unlock(&bdev->bd_mutex);
1964 bdput(bdev);
1965
1966 return 0;
1967 }
1968
blkfront_is_ready(struct xenbus_device * dev)1969 static int blkfront_is_ready(struct xenbus_device *dev)
1970 {
1971 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1972
1973 return info->is_ready && info->xbdev;
1974 }
1975
blkif_open(struct block_device * bdev,fmode_t mode)1976 static int blkif_open(struct block_device *bdev, fmode_t mode)
1977 {
1978 struct gendisk *disk = bdev->bd_disk;
1979 struct blkfront_info *info;
1980 int err = 0;
1981
1982 mutex_lock(&blkfront_mutex);
1983
1984 info = disk->private_data;
1985 if (!info) {
1986 /* xbdev gone */
1987 err = -ERESTARTSYS;
1988 goto out;
1989 }
1990
1991 mutex_lock(&info->mutex);
1992
1993 if (!info->gd)
1994 /* xbdev is closed */
1995 err = -ERESTARTSYS;
1996
1997 mutex_unlock(&info->mutex);
1998
1999 out:
2000 mutex_unlock(&blkfront_mutex);
2001 return err;
2002 }
2003
blkif_release(struct gendisk * disk,fmode_t mode)2004 static void blkif_release(struct gendisk *disk, fmode_t mode)
2005 {
2006 struct blkfront_info *info = disk->private_data;
2007 struct block_device *bdev;
2008 struct xenbus_device *xbdev;
2009
2010 mutex_lock(&blkfront_mutex);
2011
2012 bdev = bdget_disk(disk, 0);
2013
2014 if (!bdev) {
2015 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2016 goto out_mutex;
2017 }
2018 if (bdev->bd_openers)
2019 goto out;
2020
2021 /*
2022 * Check if we have been instructed to close. We will have
2023 * deferred this request, because the bdev was still open.
2024 */
2025
2026 mutex_lock(&info->mutex);
2027 xbdev = info->xbdev;
2028
2029 if (xbdev && xbdev->state == XenbusStateClosing) {
2030 /* pending switch to state closed */
2031 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2032 xlvbd_release_gendisk(info);
2033 xenbus_frontend_closed(info->xbdev);
2034 }
2035
2036 mutex_unlock(&info->mutex);
2037
2038 if (!xbdev) {
2039 /* sudden device removal */
2040 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2041 xlvbd_release_gendisk(info);
2042 disk->private_data = NULL;
2043 kfree(info);
2044 }
2045
2046 out:
2047 bdput(bdev);
2048 out_mutex:
2049 mutex_unlock(&blkfront_mutex);
2050 }
2051
2052 static const struct block_device_operations xlvbd_block_fops =
2053 {
2054 .owner = THIS_MODULE,
2055 .open = blkif_open,
2056 .release = blkif_release,
2057 .getgeo = blkif_getgeo,
2058 .ioctl = blkif_ioctl,
2059 };
2060
2061
2062 static const struct xenbus_device_id blkfront_ids[] = {
2063 { "vbd" },
2064 { "" }
2065 };
2066
2067 static struct xenbus_driver blkfront_driver = {
2068 .ids = blkfront_ids,
2069 .probe = blkfront_probe,
2070 .remove = blkfront_remove,
2071 .resume = blkfront_resume,
2072 .otherend_changed = blkback_changed,
2073 .is_ready = blkfront_is_ready,
2074 };
2075
xlblk_init(void)2076 static int __init xlblk_init(void)
2077 {
2078 int ret;
2079
2080 if (!xen_domain())
2081 return -ENODEV;
2082
2083 if (!xen_has_pv_disk_devices())
2084 return -ENODEV;
2085
2086 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2087 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2088 XENVBD_MAJOR, DEV_NAME);
2089 return -ENODEV;
2090 }
2091
2092 ret = xenbus_register_frontend(&blkfront_driver);
2093 if (ret) {
2094 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2095 return ret;
2096 }
2097
2098 return 0;
2099 }
2100 module_init(xlblk_init);
2101
2102
xlblk_exit(void)2103 static void __exit xlblk_exit(void)
2104 {
2105 xenbus_unregister_driver(&blkfront_driver);
2106 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2107 kfree(minors);
2108 }
2109 module_exit(xlblk_exit);
2110
2111 MODULE_DESCRIPTION("Xen virtual block device frontend");
2112 MODULE_LICENSE("GPL");
2113 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2114 MODULE_ALIAS("xen:vbd");
2115 MODULE_ALIAS("xenblk");
2116