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9f27ee59 JF |
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/module.h> | |
41 | ||
42 | #include <xen/xenbus.h> | |
43 | #include <xen/grant_table.h> | |
44 | #include <xen/events.h> | |
45 | #include <xen/page.h> | |
46 | ||
47 | #include <xen/interface/grant_table.h> | |
48 | #include <xen/interface/io/blkif.h> | |
49 | ||
50 | #include <asm/xen/hypervisor.h> | |
51 | ||
52 | enum blkif_state { | |
53 | BLKIF_STATE_DISCONNECTED, | |
54 | BLKIF_STATE_CONNECTED, | |
55 | BLKIF_STATE_SUSPENDED, | |
56 | }; | |
57 | ||
58 | struct blk_shadow { | |
59 | struct blkif_request req; | |
60 | unsigned long request; | |
61 | unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
62 | }; | |
63 | ||
64 | static struct block_device_operations xlvbd_block_fops; | |
65 | ||
66 | #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE) | |
67 | ||
68 | /* | |
69 | * We have one of these per vbd, whether ide, scsi or 'other'. They | |
70 | * hang in private_data off the gendisk structure. We may end up | |
71 | * putting all kinds of interesting stuff here :-) | |
72 | */ | |
73 | struct blkfront_info | |
74 | { | |
75 | struct xenbus_device *xbdev; | |
76 | dev_t dev; | |
77 | struct gendisk *gd; | |
78 | int vdevice; | |
79 | blkif_vdev_t handle; | |
80 | enum blkif_state connected; | |
81 | int ring_ref; | |
82 | struct blkif_front_ring ring; | |
83 | unsigned int evtchn, irq; | |
84 | struct request_queue *rq; | |
85 | struct work_struct work; | |
86 | struct gnttab_free_callback callback; | |
87 | struct blk_shadow shadow[BLK_RING_SIZE]; | |
88 | unsigned long shadow_free; | |
89 | int feature_barrier; | |
90 | ||
91 | /** | |
92 | * The number of people holding this device open. We won't allow a | |
93 | * hot-unplug unless this is 0. | |
94 | */ | |
95 | int users; | |
96 | }; | |
97 | ||
98 | static DEFINE_SPINLOCK(blkif_io_lock); | |
99 | ||
100 | #define MAXIMUM_OUTSTANDING_BLOCK_REQS \ | |
101 | (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) | |
102 | #define GRANT_INVALID_REF 0 | |
103 | ||
104 | #define PARTS_PER_DISK 16 | |
105 | ||
106 | #define BLKIF_MAJOR(dev) ((dev)>>8) | |
107 | #define BLKIF_MINOR(dev) ((dev) & 0xff) | |
108 | ||
109 | #define DEV_NAME "xvd" /* name in /dev */ | |
110 | ||
111 | /* Information about our VBDs. */ | |
112 | #define MAX_VBDS 64 | |
113 | static LIST_HEAD(vbds_list); | |
114 | ||
115 | static int get_id_from_freelist(struct blkfront_info *info) | |
116 | { | |
117 | unsigned long free = info->shadow_free; | |
118 | BUG_ON(free > BLK_RING_SIZE); | |
119 | info->shadow_free = info->shadow[free].req.id; | |
120 | info->shadow[free].req.id = 0x0fffffee; /* debug */ | |
121 | return free; | |
122 | } | |
123 | ||
124 | static void add_id_to_freelist(struct blkfront_info *info, | |
125 | unsigned long id) | |
126 | { | |
127 | info->shadow[id].req.id = info->shadow_free; | |
128 | info->shadow[id].request = 0; | |
129 | info->shadow_free = id; | |
130 | } | |
131 | ||
132 | static void blkif_restart_queue_callback(void *arg) | |
133 | { | |
134 | struct blkfront_info *info = (struct blkfront_info *)arg; | |
135 | schedule_work(&info->work); | |
136 | } | |
137 | ||
138 | /* | |
139 | * blkif_queue_request | |
140 | * | |
141 | * request block io | |
142 | * | |
143 | * id: for guest use only. | |
144 | * operation: BLKIF_OP_{READ,WRITE,PROBE} | |
145 | * buffer: buffer to read/write into. this should be a | |
146 | * virtual address in the guest os. | |
147 | */ | |
148 | static int blkif_queue_request(struct request *req) | |
149 | { | |
150 | struct blkfront_info *info = req->rq_disk->private_data; | |
151 | unsigned long buffer_mfn; | |
152 | struct blkif_request *ring_req; | |
153 | struct bio *bio; | |
154 | struct bio_vec *bvec; | |
155 | int idx; | |
156 | unsigned long id; | |
157 | unsigned int fsect, lsect; | |
158 | int ref; | |
159 | grant_ref_t gref_head; | |
160 | ||
161 | if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) | |
162 | return 1; | |
163 | ||
164 | if (gnttab_alloc_grant_references( | |
165 | BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) { | |
166 | gnttab_request_free_callback( | |
167 | &info->callback, | |
168 | blkif_restart_queue_callback, | |
169 | info, | |
170 | BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
171 | return 1; | |
172 | } | |
173 | ||
174 | /* Fill out a communications ring structure. */ | |
175 | ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); | |
176 | id = get_id_from_freelist(info); | |
177 | info->shadow[id].request = (unsigned long)req; | |
178 | ||
179 | ring_req->id = id; | |
180 | ring_req->sector_number = (blkif_sector_t)req->sector; | |
181 | ring_req->handle = info->handle; | |
182 | ||
183 | ring_req->operation = rq_data_dir(req) ? | |
184 | BLKIF_OP_WRITE : BLKIF_OP_READ; | |
185 | if (blk_barrier_rq(req)) | |
186 | ring_req->operation = BLKIF_OP_WRITE_BARRIER; | |
187 | ||
188 | ring_req->nr_segments = 0; | |
189 | rq_for_each_bio (bio, req) { | |
190 | bio_for_each_segment (bvec, bio, idx) { | |
191 | BUG_ON(ring_req->nr_segments | |
192 | == BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
193 | buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page)); | |
194 | fsect = bvec->bv_offset >> 9; | |
195 | lsect = fsect + (bvec->bv_len >> 9) - 1; | |
196 | /* install a grant reference. */ | |
197 | ref = gnttab_claim_grant_reference(&gref_head); | |
198 | BUG_ON(ref == -ENOSPC); | |
199 | ||
200 | gnttab_grant_foreign_access_ref( | |
201 | ref, | |
202 | info->xbdev->otherend_id, | |
203 | buffer_mfn, | |
204 | rq_data_dir(req) ); | |
205 | ||
206 | info->shadow[id].frame[ring_req->nr_segments] = | |
207 | mfn_to_pfn(buffer_mfn); | |
208 | ||
209 | ring_req->seg[ring_req->nr_segments] = | |
210 | (struct blkif_request_segment) { | |
211 | .gref = ref, | |
212 | .first_sect = fsect, | |
213 | .last_sect = lsect }; | |
214 | ||
215 | ring_req->nr_segments++; | |
216 | } | |
217 | } | |
218 | ||
219 | info->ring.req_prod_pvt++; | |
220 | ||
221 | /* Keep a private copy so we can reissue requests when recovering. */ | |
222 | info->shadow[id].req = *ring_req; | |
223 | ||
224 | gnttab_free_grant_references(gref_head); | |
225 | ||
226 | return 0; | |
227 | } | |
228 | ||
229 | ||
230 | static inline void flush_requests(struct blkfront_info *info) | |
231 | { | |
232 | int notify; | |
233 | ||
234 | RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); | |
235 | ||
236 | if (notify) | |
237 | notify_remote_via_irq(info->irq); | |
238 | } | |
239 | ||
240 | /* | |
241 | * do_blkif_request | |
242 | * read a block; request is in a request queue | |
243 | */ | |
244 | static void do_blkif_request(request_queue_t *rq) | |
245 | { | |
246 | struct blkfront_info *info = NULL; | |
247 | struct request *req; | |
248 | int queued; | |
249 | ||
250 | pr_debug("Entered do_blkif_request\n"); | |
251 | ||
252 | queued = 0; | |
253 | ||
254 | while ((req = elv_next_request(rq)) != NULL) { | |
255 | info = req->rq_disk->private_data; | |
256 | if (!blk_fs_request(req)) { | |
257 | end_request(req, 0); | |
258 | continue; | |
259 | } | |
260 | ||
261 | if (RING_FULL(&info->ring)) | |
262 | goto wait; | |
263 | ||
264 | pr_debug("do_blk_req %p: cmd %p, sec %lx, " | |
265 | "(%u/%li) buffer:%p [%s]\n", | |
266 | req, req->cmd, (unsigned long)req->sector, | |
267 | req->current_nr_sectors, | |
268 | req->nr_sectors, req->buffer, | |
269 | rq_data_dir(req) ? "write" : "read"); | |
270 | ||
271 | ||
272 | blkdev_dequeue_request(req); | |
273 | if (blkif_queue_request(req)) { | |
274 | blk_requeue_request(rq, req); | |
275 | wait: | |
276 | /* Avoid pointless unplugs. */ | |
277 | blk_stop_queue(rq); | |
278 | break; | |
279 | } | |
280 | ||
281 | queued++; | |
282 | } | |
283 | ||
284 | if (queued != 0) | |
285 | flush_requests(info); | |
286 | } | |
287 | ||
288 | static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size) | |
289 | { | |
290 | request_queue_t *rq; | |
291 | ||
292 | rq = blk_init_queue(do_blkif_request, &blkif_io_lock); | |
293 | if (rq == NULL) | |
294 | return -1; | |
295 | ||
296 | elevator_init(rq, "noop"); | |
297 | ||
298 | /* Hard sector size and max sectors impersonate the equiv. hardware. */ | |
299 | blk_queue_hardsect_size(rq, sector_size); | |
300 | blk_queue_max_sectors(rq, 512); | |
301 | ||
302 | /* Each segment in a request is up to an aligned page in size. */ | |
303 | blk_queue_segment_boundary(rq, PAGE_SIZE - 1); | |
304 | blk_queue_max_segment_size(rq, PAGE_SIZE); | |
305 | ||
306 | /* Ensure a merged request will fit in a single I/O ring slot. */ | |
307 | blk_queue_max_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
308 | blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
309 | ||
310 | /* Make sure buffer addresses are sector-aligned. */ | |
311 | blk_queue_dma_alignment(rq, 511); | |
312 | ||
313 | gd->queue = rq; | |
314 | ||
315 | return 0; | |
316 | } | |
317 | ||
318 | ||
319 | static int xlvbd_barrier(struct blkfront_info *info) | |
320 | { | |
321 | int err; | |
322 | ||
323 | err = blk_queue_ordered(info->rq, | |
324 | info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE, | |
325 | NULL); | |
326 | ||
327 | if (err) | |
328 | return err; | |
329 | ||
330 | printk(KERN_INFO "blkfront: %s: barriers %s\n", | |
331 | info->gd->disk_name, | |
332 | info->feature_barrier ? "enabled" : "disabled"); | |
333 | return 0; | |
334 | } | |
335 | ||
336 | ||
337 | static int xlvbd_alloc_gendisk(int minor, blkif_sector_t capacity, | |
338 | int vdevice, u16 vdisk_info, u16 sector_size, | |
339 | struct blkfront_info *info) | |
340 | { | |
341 | struct gendisk *gd; | |
342 | int nr_minors = 1; | |
343 | int err = -ENODEV; | |
344 | ||
345 | BUG_ON(info->gd != NULL); | |
346 | BUG_ON(info->rq != NULL); | |
347 | ||
348 | if ((minor % PARTS_PER_DISK) == 0) | |
349 | nr_minors = PARTS_PER_DISK; | |
350 | ||
351 | gd = alloc_disk(nr_minors); | |
352 | if (gd == NULL) | |
353 | goto out; | |
354 | ||
355 | if (nr_minors > 1) | |
356 | sprintf(gd->disk_name, "%s%c", DEV_NAME, | |
357 | 'a' + minor / PARTS_PER_DISK); | |
358 | else | |
359 | sprintf(gd->disk_name, "%s%c%d", DEV_NAME, | |
360 | 'a' + minor / PARTS_PER_DISK, | |
361 | minor % PARTS_PER_DISK); | |
362 | ||
363 | gd->major = XENVBD_MAJOR; | |
364 | gd->first_minor = minor; | |
365 | gd->fops = &xlvbd_block_fops; | |
366 | gd->private_data = info; | |
367 | gd->driverfs_dev = &(info->xbdev->dev); | |
368 | set_capacity(gd, capacity); | |
369 | ||
370 | if (xlvbd_init_blk_queue(gd, sector_size)) { | |
371 | del_gendisk(gd); | |
372 | goto out; | |
373 | } | |
374 | ||
375 | info->rq = gd->queue; | |
376 | info->gd = gd; | |
377 | ||
378 | if (info->feature_barrier) | |
379 | xlvbd_barrier(info); | |
380 | ||
381 | if (vdisk_info & VDISK_READONLY) | |
382 | set_disk_ro(gd, 1); | |
383 | ||
384 | if (vdisk_info & VDISK_REMOVABLE) | |
385 | gd->flags |= GENHD_FL_REMOVABLE; | |
386 | ||
387 | if (vdisk_info & VDISK_CDROM) | |
388 | gd->flags |= GENHD_FL_CD; | |
389 | ||
390 | return 0; | |
391 | ||
392 | out: | |
393 | return err; | |
394 | } | |
395 | ||
396 | static void kick_pending_request_queues(struct blkfront_info *info) | |
397 | { | |
398 | if (!RING_FULL(&info->ring)) { | |
399 | /* Re-enable calldowns. */ | |
400 | blk_start_queue(info->rq); | |
401 | /* Kick things off immediately. */ | |
402 | do_blkif_request(info->rq); | |
403 | } | |
404 | } | |
405 | ||
406 | static void blkif_restart_queue(struct work_struct *work) | |
407 | { | |
408 | struct blkfront_info *info = container_of(work, struct blkfront_info, work); | |
409 | ||
410 | spin_lock_irq(&blkif_io_lock); | |
411 | if (info->connected == BLKIF_STATE_CONNECTED) | |
412 | kick_pending_request_queues(info); | |
413 | spin_unlock_irq(&blkif_io_lock); | |
414 | } | |
415 | ||
416 | static void blkif_free(struct blkfront_info *info, int suspend) | |
417 | { | |
418 | /* Prevent new requests being issued until we fix things up. */ | |
419 | spin_lock_irq(&blkif_io_lock); | |
420 | info->connected = suspend ? | |
421 | BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; | |
422 | /* No more blkif_request(). */ | |
423 | if (info->rq) | |
424 | blk_stop_queue(info->rq); | |
425 | /* No more gnttab callback work. */ | |
426 | gnttab_cancel_free_callback(&info->callback); | |
427 | spin_unlock_irq(&blkif_io_lock); | |
428 | ||
429 | /* Flush gnttab callback work. Must be done with no locks held. */ | |
430 | flush_scheduled_work(); | |
431 | ||
432 | /* Free resources associated with old device channel. */ | |
433 | if (info->ring_ref != GRANT_INVALID_REF) { | |
434 | gnttab_end_foreign_access(info->ring_ref, 0, | |
435 | (unsigned long)info->ring.sring); | |
436 | info->ring_ref = GRANT_INVALID_REF; | |
437 | info->ring.sring = NULL; | |
438 | } | |
439 | if (info->irq) | |
440 | unbind_from_irqhandler(info->irq, info); | |
441 | info->evtchn = info->irq = 0; | |
442 | ||
443 | } | |
444 | ||
445 | static void blkif_completion(struct blk_shadow *s) | |
446 | { | |
447 | int i; | |
448 | for (i = 0; i < s->req.nr_segments; i++) | |
449 | gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL); | |
450 | } | |
451 | ||
452 | static irqreturn_t blkif_interrupt(int irq, void *dev_id) | |
453 | { | |
454 | struct request *req; | |
455 | struct blkif_response *bret; | |
456 | RING_IDX i, rp; | |
457 | unsigned long flags; | |
458 | struct blkfront_info *info = (struct blkfront_info *)dev_id; | |
459 | int uptodate; | |
460 | ||
461 | spin_lock_irqsave(&blkif_io_lock, flags); | |
462 | ||
463 | if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { | |
464 | spin_unlock_irqrestore(&blkif_io_lock, flags); | |
465 | return IRQ_HANDLED; | |
466 | } | |
467 | ||
468 | again: | |
469 | rp = info->ring.sring->rsp_prod; | |
470 | rmb(); /* Ensure we see queued responses up to 'rp'. */ | |
471 | ||
472 | for (i = info->ring.rsp_cons; i != rp; i++) { | |
473 | unsigned long id; | |
474 | int ret; | |
475 | ||
476 | bret = RING_GET_RESPONSE(&info->ring, i); | |
477 | id = bret->id; | |
478 | req = (struct request *)info->shadow[id].request; | |
479 | ||
480 | blkif_completion(&info->shadow[id]); | |
481 | ||
482 | add_id_to_freelist(info, id); | |
483 | ||
484 | uptodate = (bret->status == BLKIF_RSP_OKAY); | |
485 | switch (bret->operation) { | |
486 | case BLKIF_OP_WRITE_BARRIER: | |
487 | if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { | |
488 | printk(KERN_WARNING "blkfront: %s: write barrier op failed\n", | |
489 | info->gd->disk_name); | |
490 | uptodate = -EOPNOTSUPP; | |
491 | info->feature_barrier = 0; | |
492 | xlvbd_barrier(info); | |
493 | } | |
494 | /* fall through */ | |
495 | case BLKIF_OP_READ: | |
496 | case BLKIF_OP_WRITE: | |
497 | if (unlikely(bret->status != BLKIF_RSP_OKAY)) | |
498 | dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " | |
499 | "request: %x\n", bret->status); | |
500 | ||
501 | ret = end_that_request_first(req, uptodate, | |
502 | req->hard_nr_sectors); | |
503 | BUG_ON(ret); | |
504 | end_that_request_last(req, uptodate); | |
505 | break; | |
506 | default: | |
507 | BUG(); | |
508 | } | |
509 | } | |
510 | ||
511 | info->ring.rsp_cons = i; | |
512 | ||
513 | if (i != info->ring.req_prod_pvt) { | |
514 | int more_to_do; | |
515 | RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); | |
516 | if (more_to_do) | |
517 | goto again; | |
518 | } else | |
519 | info->ring.sring->rsp_event = i + 1; | |
520 | ||
521 | kick_pending_request_queues(info); | |
522 | ||
523 | spin_unlock_irqrestore(&blkif_io_lock, flags); | |
524 | ||
525 | return IRQ_HANDLED; | |
526 | } | |
527 | ||
528 | ||
529 | static int setup_blkring(struct xenbus_device *dev, | |
530 | struct blkfront_info *info) | |
531 | { | |
532 | struct blkif_sring *sring; | |
533 | int err; | |
534 | ||
535 | info->ring_ref = GRANT_INVALID_REF; | |
536 | ||
537 | sring = (struct blkif_sring *)__get_free_page(GFP_KERNEL); | |
538 | if (!sring) { | |
539 | xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); | |
540 | return -ENOMEM; | |
541 | } | |
542 | SHARED_RING_INIT(sring); | |
543 | FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); | |
544 | ||
545 | err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); | |
546 | if (err < 0) { | |
547 | free_page((unsigned long)sring); | |
548 | info->ring.sring = NULL; | |
549 | goto fail; | |
550 | } | |
551 | info->ring_ref = err; | |
552 | ||
553 | err = xenbus_alloc_evtchn(dev, &info->evtchn); | |
554 | if (err) | |
555 | goto fail; | |
556 | ||
557 | err = bind_evtchn_to_irqhandler(info->evtchn, | |
558 | blkif_interrupt, | |
559 | IRQF_SAMPLE_RANDOM, "blkif", info); | |
560 | if (err <= 0) { | |
561 | xenbus_dev_fatal(dev, err, | |
562 | "bind_evtchn_to_irqhandler failed"); | |
563 | goto fail; | |
564 | } | |
565 | info->irq = err; | |
566 | ||
567 | return 0; | |
568 | fail: | |
569 | blkif_free(info, 0); | |
570 | return err; | |
571 | } | |
572 | ||
573 | ||
574 | /* Common code used when first setting up, and when resuming. */ | |
575 | static int talk_to_backend(struct xenbus_device *dev, | |
576 | struct blkfront_info *info) | |
577 | { | |
578 | const char *message = NULL; | |
579 | struct xenbus_transaction xbt; | |
580 | int err; | |
581 | ||
582 | /* Create shared ring, alloc event channel. */ | |
583 | err = setup_blkring(dev, info); | |
584 | if (err) | |
585 | goto out; | |
586 | ||
587 | again: | |
588 | err = xenbus_transaction_start(&xbt); | |
589 | if (err) { | |
590 | xenbus_dev_fatal(dev, err, "starting transaction"); | |
591 | goto destroy_blkring; | |
592 | } | |
593 | ||
594 | err = xenbus_printf(xbt, dev->nodename, | |
595 | "ring-ref", "%u", info->ring_ref); | |
596 | if (err) { | |
597 | message = "writing ring-ref"; | |
598 | goto abort_transaction; | |
599 | } | |
600 | err = xenbus_printf(xbt, dev->nodename, | |
601 | "event-channel", "%u", info->evtchn); | |
602 | if (err) { | |
603 | message = "writing event-channel"; | |
604 | goto abort_transaction; | |
605 | } | |
606 | ||
607 | err = xenbus_transaction_end(xbt, 0); | |
608 | if (err) { | |
609 | if (err == -EAGAIN) | |
610 | goto again; | |
611 | xenbus_dev_fatal(dev, err, "completing transaction"); | |
612 | goto destroy_blkring; | |
613 | } | |
614 | ||
615 | xenbus_switch_state(dev, XenbusStateInitialised); | |
616 | ||
617 | return 0; | |
618 | ||
619 | abort_transaction: | |
620 | xenbus_transaction_end(xbt, 1); | |
621 | if (message) | |
622 | xenbus_dev_fatal(dev, err, "%s", message); | |
623 | destroy_blkring: | |
624 | blkif_free(info, 0); | |
625 | out: | |
626 | return err; | |
627 | } | |
628 | ||
629 | ||
630 | /** | |
631 | * Entry point to this code when a new device is created. Allocate the basic | |
632 | * structures and the ring buffer for communication with the backend, and | |
633 | * inform the backend of the appropriate details for those. Switch to | |
634 | * Initialised state. | |
635 | */ | |
636 | static int blkfront_probe(struct xenbus_device *dev, | |
637 | const struct xenbus_device_id *id) | |
638 | { | |
639 | int err, vdevice, i; | |
640 | struct blkfront_info *info; | |
641 | ||
642 | /* FIXME: Use dynamic device id if this is not set. */ | |
643 | err = xenbus_scanf(XBT_NIL, dev->nodename, | |
644 | "virtual-device", "%i", &vdevice); | |
645 | if (err != 1) { | |
646 | xenbus_dev_fatal(dev, err, "reading virtual-device"); | |
647 | return err; | |
648 | } | |
649 | ||
650 | info = kzalloc(sizeof(*info), GFP_KERNEL); | |
651 | if (!info) { | |
652 | xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); | |
653 | return -ENOMEM; | |
654 | } | |
655 | ||
656 | info->xbdev = dev; | |
657 | info->vdevice = vdevice; | |
658 | info->connected = BLKIF_STATE_DISCONNECTED; | |
659 | INIT_WORK(&info->work, blkif_restart_queue); | |
660 | ||
661 | for (i = 0; i < BLK_RING_SIZE; i++) | |
662 | info->shadow[i].req.id = i+1; | |
663 | info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff; | |
664 | ||
665 | /* Front end dir is a number, which is used as the id. */ | |
666 | info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); | |
667 | dev->dev.driver_data = info; | |
668 | ||
669 | err = talk_to_backend(dev, info); | |
670 | if (err) { | |
671 | kfree(info); | |
672 | dev->dev.driver_data = NULL; | |
673 | return err; | |
674 | } | |
675 | ||
676 | return 0; | |
677 | } | |
678 | ||
679 | ||
680 | static int blkif_recover(struct blkfront_info *info) | |
681 | { | |
682 | int i; | |
683 | struct blkif_request *req; | |
684 | struct blk_shadow *copy; | |
685 | int j; | |
686 | ||
687 | /* Stage 1: Make a safe copy of the shadow state. */ | |
688 | copy = kmalloc(sizeof(info->shadow), GFP_KERNEL); | |
689 | if (!copy) | |
690 | return -ENOMEM; | |
691 | memcpy(copy, info->shadow, sizeof(info->shadow)); | |
692 | ||
693 | /* Stage 2: Set up free list. */ | |
694 | memset(&info->shadow, 0, sizeof(info->shadow)); | |
695 | for (i = 0; i < BLK_RING_SIZE; i++) | |
696 | info->shadow[i].req.id = i+1; | |
697 | info->shadow_free = info->ring.req_prod_pvt; | |
698 | info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff; | |
699 | ||
700 | /* Stage 3: Find pending requests and requeue them. */ | |
701 | for (i = 0; i < BLK_RING_SIZE; i++) { | |
702 | /* Not in use? */ | |
703 | if (copy[i].request == 0) | |
704 | continue; | |
705 | ||
706 | /* Grab a request slot and copy shadow state into it. */ | |
707 | req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); | |
708 | *req = copy[i].req; | |
709 | ||
710 | /* We get a new request id, and must reset the shadow state. */ | |
711 | req->id = get_id_from_freelist(info); | |
712 | memcpy(&info->shadow[req->id], ©[i], sizeof(copy[i])); | |
713 | ||
714 | /* Rewrite any grant references invalidated by susp/resume. */ | |
715 | for (j = 0; j < req->nr_segments; j++) | |
716 | gnttab_grant_foreign_access_ref( | |
717 | req->seg[j].gref, | |
718 | info->xbdev->otherend_id, | |
719 | pfn_to_mfn(info->shadow[req->id].frame[j]), | |
720 | rq_data_dir( | |
721 | (struct request *) | |
722 | info->shadow[req->id].request)); | |
723 | info->shadow[req->id].req = *req; | |
724 | ||
725 | info->ring.req_prod_pvt++; | |
726 | } | |
727 | ||
728 | kfree(copy); | |
729 | ||
730 | xenbus_switch_state(info->xbdev, XenbusStateConnected); | |
731 | ||
732 | spin_lock_irq(&blkif_io_lock); | |
733 | ||
734 | /* Now safe for us to use the shared ring */ | |
735 | info->connected = BLKIF_STATE_CONNECTED; | |
736 | ||
737 | /* Send off requeued requests */ | |
738 | flush_requests(info); | |
739 | ||
740 | /* Kick any other new requests queued since we resumed */ | |
741 | kick_pending_request_queues(info); | |
742 | ||
743 | spin_unlock_irq(&blkif_io_lock); | |
744 | ||
745 | return 0; | |
746 | } | |
747 | ||
748 | /** | |
749 | * We are reconnecting to the backend, due to a suspend/resume, or a backend | |
750 | * driver restart. We tear down our blkif structure and recreate it, but | |
751 | * leave the device-layer structures intact so that this is transparent to the | |
752 | * rest of the kernel. | |
753 | */ | |
754 | static int blkfront_resume(struct xenbus_device *dev) | |
755 | { | |
756 | struct blkfront_info *info = dev->dev.driver_data; | |
757 | int err; | |
758 | ||
759 | dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); | |
760 | ||
761 | blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); | |
762 | ||
763 | err = talk_to_backend(dev, info); | |
764 | if (info->connected == BLKIF_STATE_SUSPENDED && !err) | |
765 | err = blkif_recover(info); | |
766 | ||
767 | return err; | |
768 | } | |
769 | ||
770 | ||
771 | /* | |
772 | * Invoked when the backend is finally 'ready' (and has told produced | |
773 | * the details about the physical device - #sectors, size, etc). | |
774 | */ | |
775 | static void blkfront_connect(struct blkfront_info *info) | |
776 | { | |
777 | unsigned long long sectors; | |
778 | unsigned long sector_size; | |
779 | unsigned int binfo; | |
780 | int err; | |
781 | ||
782 | if ((info->connected == BLKIF_STATE_CONNECTED) || | |
783 | (info->connected == BLKIF_STATE_SUSPENDED) ) | |
784 | return; | |
785 | ||
786 | dev_dbg(&info->xbdev->dev, "%s:%s.\n", | |
787 | __func__, info->xbdev->otherend); | |
788 | ||
789 | err = xenbus_gather(XBT_NIL, info->xbdev->otherend, | |
790 | "sectors", "%llu", §ors, | |
791 | "info", "%u", &binfo, | |
792 | "sector-size", "%lu", §or_size, | |
793 | NULL); | |
794 | if (err) { | |
795 | xenbus_dev_fatal(info->xbdev, err, | |
796 | "reading backend fields at %s", | |
797 | info->xbdev->otherend); | |
798 | return; | |
799 | } | |
800 | ||
801 | err = xenbus_gather(XBT_NIL, info->xbdev->otherend, | |
802 | "feature-barrier", "%lu", &info->feature_barrier, | |
803 | NULL); | |
804 | if (err) | |
805 | info->feature_barrier = 0; | |
806 | ||
807 | err = xlvbd_alloc_gendisk(BLKIF_MINOR(info->vdevice), | |
808 | sectors, info->vdevice, | |
809 | binfo, sector_size, info); | |
810 | if (err) { | |
811 | xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", | |
812 | info->xbdev->otherend); | |
813 | return; | |
814 | } | |
815 | ||
816 | xenbus_switch_state(info->xbdev, XenbusStateConnected); | |
817 | ||
818 | /* Kick pending requests. */ | |
819 | spin_lock_irq(&blkif_io_lock); | |
820 | info->connected = BLKIF_STATE_CONNECTED; | |
821 | kick_pending_request_queues(info); | |
822 | spin_unlock_irq(&blkif_io_lock); | |
823 | ||
824 | add_disk(info->gd); | |
825 | } | |
826 | ||
827 | /** | |
828 | * Handle the change of state of the backend to Closing. We must delete our | |
829 | * device-layer structures now, to ensure that writes are flushed through to | |
830 | * the backend. Once is this done, we can switch to Closed in | |
831 | * acknowledgement. | |
832 | */ | |
833 | static void blkfront_closing(struct xenbus_device *dev) | |
834 | { | |
835 | struct blkfront_info *info = dev->dev.driver_data; | |
836 | unsigned long flags; | |
837 | ||
838 | dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename); | |
839 | ||
840 | if (info->rq == NULL) | |
841 | goto out; | |
842 | ||
843 | spin_lock_irqsave(&blkif_io_lock, flags); | |
844 | ||
845 | del_gendisk(info->gd); | |
846 | ||
847 | /* No more blkif_request(). */ | |
848 | blk_stop_queue(info->rq); | |
849 | ||
850 | /* No more gnttab callback work. */ | |
851 | gnttab_cancel_free_callback(&info->callback); | |
852 | spin_unlock_irqrestore(&blkif_io_lock, flags); | |
853 | ||
854 | /* Flush gnttab callback work. Must be done with no locks held. */ | |
855 | flush_scheduled_work(); | |
856 | ||
857 | blk_cleanup_queue(info->rq); | |
858 | info->rq = NULL; | |
859 | ||
860 | out: | |
861 | xenbus_frontend_closed(dev); | |
862 | } | |
863 | ||
864 | /** | |
865 | * Callback received when the backend's state changes. | |
866 | */ | |
867 | static void backend_changed(struct xenbus_device *dev, | |
868 | enum xenbus_state backend_state) | |
869 | { | |
870 | struct blkfront_info *info = dev->dev.driver_data; | |
871 | struct block_device *bd; | |
872 | ||
873 | dev_dbg(&dev->dev, "blkfront:backend_changed.\n"); | |
874 | ||
875 | switch (backend_state) { | |
876 | case XenbusStateInitialising: | |
877 | case XenbusStateInitWait: | |
878 | case XenbusStateInitialised: | |
879 | case XenbusStateUnknown: | |
880 | case XenbusStateClosed: | |
881 | break; | |
882 | ||
883 | case XenbusStateConnected: | |
884 | blkfront_connect(info); | |
885 | break; | |
886 | ||
887 | case XenbusStateClosing: | |
888 | bd = bdget(info->dev); | |
889 | if (bd == NULL) | |
890 | xenbus_dev_fatal(dev, -ENODEV, "bdget failed"); | |
891 | ||
892 | mutex_lock(&bd->bd_mutex); | |
893 | if (info->users > 0) | |
894 | xenbus_dev_error(dev, -EBUSY, | |
895 | "Device in use; refusing to close"); | |
896 | else | |
897 | blkfront_closing(dev); | |
898 | mutex_unlock(&bd->bd_mutex); | |
899 | bdput(bd); | |
900 | break; | |
901 | } | |
902 | } | |
903 | ||
904 | static int blkfront_remove(struct xenbus_device *dev) | |
905 | { | |
906 | struct blkfront_info *info = dev->dev.driver_data; | |
907 | ||
908 | dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename); | |
909 | ||
910 | blkif_free(info, 0); | |
911 | ||
912 | kfree(info); | |
913 | ||
914 | return 0; | |
915 | } | |
916 | ||
917 | static int blkif_open(struct inode *inode, struct file *filep) | |
918 | { | |
919 | struct blkfront_info *info = inode->i_bdev->bd_disk->private_data; | |
920 | info->users++; | |
921 | return 0; | |
922 | } | |
923 | ||
924 | static int blkif_release(struct inode *inode, struct file *filep) | |
925 | { | |
926 | struct blkfront_info *info = inode->i_bdev->bd_disk->private_data; | |
927 | info->users--; | |
928 | if (info->users == 0) { | |
929 | /* Check whether we have been instructed to close. We will | |
930 | have ignored this request initially, as the device was | |
931 | still mounted. */ | |
932 | struct xenbus_device *dev = info->xbdev; | |
933 | enum xenbus_state state = xenbus_read_driver_state(dev->otherend); | |
934 | ||
935 | if (state == XenbusStateClosing) | |
936 | blkfront_closing(dev); | |
937 | } | |
938 | return 0; | |
939 | } | |
940 | ||
941 | static struct block_device_operations xlvbd_block_fops = | |
942 | { | |
943 | .owner = THIS_MODULE, | |
944 | .open = blkif_open, | |
945 | .release = blkif_release, | |
946 | }; | |
947 | ||
948 | ||
949 | static struct xenbus_device_id blkfront_ids[] = { | |
950 | { "vbd" }, | |
951 | { "" } | |
952 | }; | |
953 | ||
954 | static struct xenbus_driver blkfront = { | |
955 | .name = "vbd", | |
956 | .owner = THIS_MODULE, | |
957 | .ids = blkfront_ids, | |
958 | .probe = blkfront_probe, | |
959 | .remove = blkfront_remove, | |
960 | .resume = blkfront_resume, | |
961 | .otherend_changed = backend_changed, | |
962 | }; | |
963 | ||
964 | static int __init xlblk_init(void) | |
965 | { | |
966 | if (!is_running_on_xen()) | |
967 | return -ENODEV; | |
968 | ||
969 | if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { | |
970 | printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", | |
971 | XENVBD_MAJOR, DEV_NAME); | |
972 | return -ENODEV; | |
973 | } | |
974 | ||
975 | return xenbus_register_frontend(&blkfront); | |
976 | } | |
977 | module_init(xlblk_init); | |
978 | ||
979 | ||
980 | static void xlblk_exit(void) | |
981 | { | |
982 | return xenbus_unregister_driver(&blkfront); | |
983 | } | |
984 | module_exit(xlblk_exit); | |
985 | ||
986 | MODULE_DESCRIPTION("Xen virtual block device frontend"); | |
987 | MODULE_LICENSE("GPL"); | |
988 | MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); |