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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; | |
5705f702 | 153 | struct req_iterator iter; |
9f27ee59 | 154 | struct bio_vec *bvec; |
9f27ee59 JF |
155 | unsigned long id; |
156 | unsigned int fsect, lsect; | |
157 | int ref; | |
158 | grant_ref_t gref_head; | |
159 | ||
160 | if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) | |
161 | return 1; | |
162 | ||
163 | if (gnttab_alloc_grant_references( | |
164 | BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) { | |
165 | gnttab_request_free_callback( | |
166 | &info->callback, | |
167 | blkif_restart_queue_callback, | |
168 | info, | |
169 | BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
170 | return 1; | |
171 | } | |
172 | ||
173 | /* Fill out a communications ring structure. */ | |
174 | ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); | |
175 | id = get_id_from_freelist(info); | |
176 | info->shadow[id].request = (unsigned long)req; | |
177 | ||
178 | ring_req->id = id; | |
179 | ring_req->sector_number = (blkif_sector_t)req->sector; | |
180 | ring_req->handle = info->handle; | |
181 | ||
182 | ring_req->operation = rq_data_dir(req) ? | |
183 | BLKIF_OP_WRITE : BLKIF_OP_READ; | |
184 | if (blk_barrier_rq(req)) | |
185 | ring_req->operation = BLKIF_OP_WRITE_BARRIER; | |
186 | ||
187 | ring_req->nr_segments = 0; | |
5705f702 | 188 | rq_for_each_segment(bvec, req, iter) { |
6c92e699 JA |
189 | BUG_ON(ring_req->nr_segments == BLKIF_MAX_SEGMENTS_PER_REQUEST); |
190 | buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page)); | |
191 | fsect = bvec->bv_offset >> 9; | |
192 | lsect = fsect + (bvec->bv_len >> 9) - 1; | |
193 | /* install a grant reference. */ | |
194 | ref = gnttab_claim_grant_reference(&gref_head); | |
195 | BUG_ON(ref == -ENOSPC); | |
196 | ||
197 | gnttab_grant_foreign_access_ref( | |
9f27ee59 JF |
198 | ref, |
199 | info->xbdev->otherend_id, | |
200 | buffer_mfn, | |
201 | rq_data_dir(req) ); | |
202 | ||
6c92e699 | 203 | info->shadow[id].frame[ring_req->nr_segments] = |
9f27ee59 JF |
204 | mfn_to_pfn(buffer_mfn); |
205 | ||
6c92e699 | 206 | ring_req->seg[ring_req->nr_segments] = |
9f27ee59 JF |
207 | (struct blkif_request_segment) { |
208 | .gref = ref, | |
209 | .first_sect = fsect, | |
210 | .last_sect = lsect }; | |
211 | ||
6c92e699 | 212 | ring_req->nr_segments++; |
9f27ee59 JF |
213 | } |
214 | ||
215 | info->ring.req_prod_pvt++; | |
216 | ||
217 | /* Keep a private copy so we can reissue requests when recovering. */ | |
218 | info->shadow[id].req = *ring_req; | |
219 | ||
220 | gnttab_free_grant_references(gref_head); | |
221 | ||
222 | return 0; | |
223 | } | |
224 | ||
225 | ||
226 | static inline void flush_requests(struct blkfront_info *info) | |
227 | { | |
228 | int notify; | |
229 | ||
230 | RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); | |
231 | ||
232 | if (notify) | |
233 | notify_remote_via_irq(info->irq); | |
234 | } | |
235 | ||
236 | /* | |
237 | * do_blkif_request | |
238 | * read a block; request is in a request queue | |
239 | */ | |
165125e1 | 240 | static void do_blkif_request(struct request_queue *rq) |
9f27ee59 JF |
241 | { |
242 | struct blkfront_info *info = NULL; | |
243 | struct request *req; | |
244 | int queued; | |
245 | ||
246 | pr_debug("Entered do_blkif_request\n"); | |
247 | ||
248 | queued = 0; | |
249 | ||
250 | while ((req = elv_next_request(rq)) != NULL) { | |
251 | info = req->rq_disk->private_data; | |
252 | if (!blk_fs_request(req)) { | |
253 | end_request(req, 0); | |
254 | continue; | |
255 | } | |
256 | ||
257 | if (RING_FULL(&info->ring)) | |
258 | goto wait; | |
259 | ||
260 | pr_debug("do_blk_req %p: cmd %p, sec %lx, " | |
261 | "(%u/%li) buffer:%p [%s]\n", | |
262 | req, req->cmd, (unsigned long)req->sector, | |
263 | req->current_nr_sectors, | |
264 | req->nr_sectors, req->buffer, | |
265 | rq_data_dir(req) ? "write" : "read"); | |
266 | ||
267 | ||
268 | blkdev_dequeue_request(req); | |
269 | if (blkif_queue_request(req)) { | |
270 | blk_requeue_request(rq, req); | |
271 | wait: | |
272 | /* Avoid pointless unplugs. */ | |
273 | blk_stop_queue(rq); | |
274 | break; | |
275 | } | |
276 | ||
277 | queued++; | |
278 | } | |
279 | ||
280 | if (queued != 0) | |
281 | flush_requests(info); | |
282 | } | |
283 | ||
284 | static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size) | |
285 | { | |
165125e1 | 286 | struct request_queue *rq; |
9f27ee59 JF |
287 | |
288 | rq = blk_init_queue(do_blkif_request, &blkif_io_lock); | |
289 | if (rq == NULL) | |
290 | return -1; | |
291 | ||
292 | elevator_init(rq, "noop"); | |
293 | ||
294 | /* Hard sector size and max sectors impersonate the equiv. hardware. */ | |
295 | blk_queue_hardsect_size(rq, sector_size); | |
296 | blk_queue_max_sectors(rq, 512); | |
297 | ||
298 | /* Each segment in a request is up to an aligned page in size. */ | |
299 | blk_queue_segment_boundary(rq, PAGE_SIZE - 1); | |
300 | blk_queue_max_segment_size(rq, PAGE_SIZE); | |
301 | ||
302 | /* Ensure a merged request will fit in a single I/O ring slot. */ | |
303 | blk_queue_max_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
304 | blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
305 | ||
306 | /* Make sure buffer addresses are sector-aligned. */ | |
307 | blk_queue_dma_alignment(rq, 511); | |
308 | ||
309 | gd->queue = rq; | |
310 | ||
311 | return 0; | |
312 | } | |
313 | ||
314 | ||
315 | static int xlvbd_barrier(struct blkfront_info *info) | |
316 | { | |
317 | int err; | |
318 | ||
319 | err = blk_queue_ordered(info->rq, | |
320 | info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE, | |
321 | NULL); | |
322 | ||
323 | if (err) | |
324 | return err; | |
325 | ||
326 | printk(KERN_INFO "blkfront: %s: barriers %s\n", | |
327 | info->gd->disk_name, | |
328 | info->feature_barrier ? "enabled" : "disabled"); | |
329 | return 0; | |
330 | } | |
331 | ||
332 | ||
333 | static int xlvbd_alloc_gendisk(int minor, blkif_sector_t capacity, | |
334 | int vdevice, u16 vdisk_info, u16 sector_size, | |
335 | struct blkfront_info *info) | |
336 | { | |
337 | struct gendisk *gd; | |
338 | int nr_minors = 1; | |
339 | int err = -ENODEV; | |
340 | ||
341 | BUG_ON(info->gd != NULL); | |
342 | BUG_ON(info->rq != NULL); | |
343 | ||
344 | if ((minor % PARTS_PER_DISK) == 0) | |
345 | nr_minors = PARTS_PER_DISK; | |
346 | ||
347 | gd = alloc_disk(nr_minors); | |
348 | if (gd == NULL) | |
349 | goto out; | |
350 | ||
351 | if (nr_minors > 1) | |
352 | sprintf(gd->disk_name, "%s%c", DEV_NAME, | |
353 | 'a' + minor / PARTS_PER_DISK); | |
354 | else | |
355 | sprintf(gd->disk_name, "%s%c%d", DEV_NAME, | |
356 | 'a' + minor / PARTS_PER_DISK, | |
357 | minor % PARTS_PER_DISK); | |
358 | ||
359 | gd->major = XENVBD_MAJOR; | |
360 | gd->first_minor = minor; | |
361 | gd->fops = &xlvbd_block_fops; | |
362 | gd->private_data = info; | |
363 | gd->driverfs_dev = &(info->xbdev->dev); | |
364 | set_capacity(gd, capacity); | |
365 | ||
366 | if (xlvbd_init_blk_queue(gd, sector_size)) { | |
367 | del_gendisk(gd); | |
368 | goto out; | |
369 | } | |
370 | ||
371 | info->rq = gd->queue; | |
372 | info->gd = gd; | |
373 | ||
374 | if (info->feature_barrier) | |
375 | xlvbd_barrier(info); | |
376 | ||
377 | if (vdisk_info & VDISK_READONLY) | |
378 | set_disk_ro(gd, 1); | |
379 | ||
380 | if (vdisk_info & VDISK_REMOVABLE) | |
381 | gd->flags |= GENHD_FL_REMOVABLE; | |
382 | ||
383 | if (vdisk_info & VDISK_CDROM) | |
384 | gd->flags |= GENHD_FL_CD; | |
385 | ||
386 | return 0; | |
387 | ||
388 | out: | |
389 | return err; | |
390 | } | |
391 | ||
392 | static void kick_pending_request_queues(struct blkfront_info *info) | |
393 | { | |
394 | if (!RING_FULL(&info->ring)) { | |
395 | /* Re-enable calldowns. */ | |
396 | blk_start_queue(info->rq); | |
397 | /* Kick things off immediately. */ | |
398 | do_blkif_request(info->rq); | |
399 | } | |
400 | } | |
401 | ||
402 | static void blkif_restart_queue(struct work_struct *work) | |
403 | { | |
404 | struct blkfront_info *info = container_of(work, struct blkfront_info, work); | |
405 | ||
406 | spin_lock_irq(&blkif_io_lock); | |
407 | if (info->connected == BLKIF_STATE_CONNECTED) | |
408 | kick_pending_request_queues(info); | |
409 | spin_unlock_irq(&blkif_io_lock); | |
410 | } | |
411 | ||
412 | static void blkif_free(struct blkfront_info *info, int suspend) | |
413 | { | |
414 | /* Prevent new requests being issued until we fix things up. */ | |
415 | spin_lock_irq(&blkif_io_lock); | |
416 | info->connected = suspend ? | |
417 | BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; | |
418 | /* No more blkif_request(). */ | |
419 | if (info->rq) | |
420 | blk_stop_queue(info->rq); | |
421 | /* No more gnttab callback work. */ | |
422 | gnttab_cancel_free_callback(&info->callback); | |
423 | spin_unlock_irq(&blkif_io_lock); | |
424 | ||
425 | /* Flush gnttab callback work. Must be done with no locks held. */ | |
426 | flush_scheduled_work(); | |
427 | ||
428 | /* Free resources associated with old device channel. */ | |
429 | if (info->ring_ref != GRANT_INVALID_REF) { | |
430 | gnttab_end_foreign_access(info->ring_ref, 0, | |
431 | (unsigned long)info->ring.sring); | |
432 | info->ring_ref = GRANT_INVALID_REF; | |
433 | info->ring.sring = NULL; | |
434 | } | |
435 | if (info->irq) | |
436 | unbind_from_irqhandler(info->irq, info); | |
437 | info->evtchn = info->irq = 0; | |
438 | ||
439 | } | |
440 | ||
441 | static void blkif_completion(struct blk_shadow *s) | |
442 | { | |
443 | int i; | |
444 | for (i = 0; i < s->req.nr_segments; i++) | |
445 | gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL); | |
446 | } | |
447 | ||
448 | static irqreturn_t blkif_interrupt(int irq, void *dev_id) | |
449 | { | |
450 | struct request *req; | |
451 | struct blkif_response *bret; | |
452 | RING_IDX i, rp; | |
453 | unsigned long flags; | |
454 | struct blkfront_info *info = (struct blkfront_info *)dev_id; | |
455 | int uptodate; | |
456 | ||
457 | spin_lock_irqsave(&blkif_io_lock, flags); | |
458 | ||
459 | if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { | |
460 | spin_unlock_irqrestore(&blkif_io_lock, flags); | |
461 | return IRQ_HANDLED; | |
462 | } | |
463 | ||
464 | again: | |
465 | rp = info->ring.sring->rsp_prod; | |
466 | rmb(); /* Ensure we see queued responses up to 'rp'. */ | |
467 | ||
468 | for (i = info->ring.rsp_cons; i != rp; i++) { | |
469 | unsigned long id; | |
470 | int ret; | |
471 | ||
472 | bret = RING_GET_RESPONSE(&info->ring, i); | |
473 | id = bret->id; | |
474 | req = (struct request *)info->shadow[id].request; | |
475 | ||
476 | blkif_completion(&info->shadow[id]); | |
477 | ||
478 | add_id_to_freelist(info, id); | |
479 | ||
480 | uptodate = (bret->status == BLKIF_RSP_OKAY); | |
481 | switch (bret->operation) { | |
482 | case BLKIF_OP_WRITE_BARRIER: | |
483 | if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { | |
484 | printk(KERN_WARNING "blkfront: %s: write barrier op failed\n", | |
485 | info->gd->disk_name); | |
486 | uptodate = -EOPNOTSUPP; | |
487 | info->feature_barrier = 0; | |
488 | xlvbd_barrier(info); | |
489 | } | |
490 | /* fall through */ | |
491 | case BLKIF_OP_READ: | |
492 | case BLKIF_OP_WRITE: | |
493 | if (unlikely(bret->status != BLKIF_RSP_OKAY)) | |
494 | dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " | |
495 | "request: %x\n", bret->status); | |
496 | ||
497 | ret = end_that_request_first(req, uptodate, | |
498 | req->hard_nr_sectors); | |
499 | BUG_ON(ret); | |
500 | end_that_request_last(req, uptodate); | |
501 | break; | |
502 | default: | |
503 | BUG(); | |
504 | } | |
505 | } | |
506 | ||
507 | info->ring.rsp_cons = i; | |
508 | ||
509 | if (i != info->ring.req_prod_pvt) { | |
510 | int more_to_do; | |
511 | RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); | |
512 | if (more_to_do) | |
513 | goto again; | |
514 | } else | |
515 | info->ring.sring->rsp_event = i + 1; | |
516 | ||
517 | kick_pending_request_queues(info); | |
518 | ||
519 | spin_unlock_irqrestore(&blkif_io_lock, flags); | |
520 | ||
521 | return IRQ_HANDLED; | |
522 | } | |
523 | ||
524 | ||
525 | static int setup_blkring(struct xenbus_device *dev, | |
526 | struct blkfront_info *info) | |
527 | { | |
528 | struct blkif_sring *sring; | |
529 | int err; | |
530 | ||
531 | info->ring_ref = GRANT_INVALID_REF; | |
532 | ||
533 | sring = (struct blkif_sring *)__get_free_page(GFP_KERNEL); | |
534 | if (!sring) { | |
535 | xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); | |
536 | return -ENOMEM; | |
537 | } | |
538 | SHARED_RING_INIT(sring); | |
539 | FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); | |
540 | ||
541 | err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); | |
542 | if (err < 0) { | |
543 | free_page((unsigned long)sring); | |
544 | info->ring.sring = NULL; | |
545 | goto fail; | |
546 | } | |
547 | info->ring_ref = err; | |
548 | ||
549 | err = xenbus_alloc_evtchn(dev, &info->evtchn); | |
550 | if (err) | |
551 | goto fail; | |
552 | ||
553 | err = bind_evtchn_to_irqhandler(info->evtchn, | |
554 | blkif_interrupt, | |
555 | IRQF_SAMPLE_RANDOM, "blkif", info); | |
556 | if (err <= 0) { | |
557 | xenbus_dev_fatal(dev, err, | |
558 | "bind_evtchn_to_irqhandler failed"); | |
559 | goto fail; | |
560 | } | |
561 | info->irq = err; | |
562 | ||
563 | return 0; | |
564 | fail: | |
565 | blkif_free(info, 0); | |
566 | return err; | |
567 | } | |
568 | ||
569 | ||
570 | /* Common code used when first setting up, and when resuming. */ | |
571 | static int talk_to_backend(struct xenbus_device *dev, | |
572 | struct blkfront_info *info) | |
573 | { | |
574 | const char *message = NULL; | |
575 | struct xenbus_transaction xbt; | |
576 | int err; | |
577 | ||
578 | /* Create shared ring, alloc event channel. */ | |
579 | err = setup_blkring(dev, info); | |
580 | if (err) | |
581 | goto out; | |
582 | ||
583 | again: | |
584 | err = xenbus_transaction_start(&xbt); | |
585 | if (err) { | |
586 | xenbus_dev_fatal(dev, err, "starting transaction"); | |
587 | goto destroy_blkring; | |
588 | } | |
589 | ||
590 | err = xenbus_printf(xbt, dev->nodename, | |
591 | "ring-ref", "%u", info->ring_ref); | |
592 | if (err) { | |
593 | message = "writing ring-ref"; | |
594 | goto abort_transaction; | |
595 | } | |
596 | err = xenbus_printf(xbt, dev->nodename, | |
597 | "event-channel", "%u", info->evtchn); | |
598 | if (err) { | |
599 | message = "writing event-channel"; | |
600 | goto abort_transaction; | |
601 | } | |
602 | ||
603 | err = xenbus_transaction_end(xbt, 0); | |
604 | if (err) { | |
605 | if (err == -EAGAIN) | |
606 | goto again; | |
607 | xenbus_dev_fatal(dev, err, "completing transaction"); | |
608 | goto destroy_blkring; | |
609 | } | |
610 | ||
611 | xenbus_switch_state(dev, XenbusStateInitialised); | |
612 | ||
613 | return 0; | |
614 | ||
615 | abort_transaction: | |
616 | xenbus_transaction_end(xbt, 1); | |
617 | if (message) | |
618 | xenbus_dev_fatal(dev, err, "%s", message); | |
619 | destroy_blkring: | |
620 | blkif_free(info, 0); | |
621 | out: | |
622 | return err; | |
623 | } | |
624 | ||
625 | ||
626 | /** | |
627 | * Entry point to this code when a new device is created. Allocate the basic | |
628 | * structures and the ring buffer for communication with the backend, and | |
629 | * inform the backend of the appropriate details for those. Switch to | |
630 | * Initialised state. | |
631 | */ | |
632 | static int blkfront_probe(struct xenbus_device *dev, | |
633 | const struct xenbus_device_id *id) | |
634 | { | |
635 | int err, vdevice, i; | |
636 | struct blkfront_info *info; | |
637 | ||
638 | /* FIXME: Use dynamic device id if this is not set. */ | |
639 | err = xenbus_scanf(XBT_NIL, dev->nodename, | |
640 | "virtual-device", "%i", &vdevice); | |
641 | if (err != 1) { | |
642 | xenbus_dev_fatal(dev, err, "reading virtual-device"); | |
643 | return err; | |
644 | } | |
645 | ||
646 | info = kzalloc(sizeof(*info), GFP_KERNEL); | |
647 | if (!info) { | |
648 | xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); | |
649 | return -ENOMEM; | |
650 | } | |
651 | ||
652 | info->xbdev = dev; | |
653 | info->vdevice = vdevice; | |
654 | info->connected = BLKIF_STATE_DISCONNECTED; | |
655 | INIT_WORK(&info->work, blkif_restart_queue); | |
656 | ||
657 | for (i = 0; i < BLK_RING_SIZE; i++) | |
658 | info->shadow[i].req.id = i+1; | |
659 | info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff; | |
660 | ||
661 | /* Front end dir is a number, which is used as the id. */ | |
662 | info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); | |
663 | dev->dev.driver_data = info; | |
664 | ||
665 | err = talk_to_backend(dev, info); | |
666 | if (err) { | |
667 | kfree(info); | |
668 | dev->dev.driver_data = NULL; | |
669 | return err; | |
670 | } | |
671 | ||
672 | return 0; | |
673 | } | |
674 | ||
675 | ||
676 | static int blkif_recover(struct blkfront_info *info) | |
677 | { | |
678 | int i; | |
679 | struct blkif_request *req; | |
680 | struct blk_shadow *copy; | |
681 | int j; | |
682 | ||
683 | /* Stage 1: Make a safe copy of the shadow state. */ | |
684 | copy = kmalloc(sizeof(info->shadow), GFP_KERNEL); | |
685 | if (!copy) | |
686 | return -ENOMEM; | |
687 | memcpy(copy, info->shadow, sizeof(info->shadow)); | |
688 | ||
689 | /* Stage 2: Set up free list. */ | |
690 | memset(&info->shadow, 0, sizeof(info->shadow)); | |
691 | for (i = 0; i < BLK_RING_SIZE; i++) | |
692 | info->shadow[i].req.id = i+1; | |
693 | info->shadow_free = info->ring.req_prod_pvt; | |
694 | info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff; | |
695 | ||
696 | /* Stage 3: Find pending requests and requeue them. */ | |
697 | for (i = 0; i < BLK_RING_SIZE; i++) { | |
698 | /* Not in use? */ | |
699 | if (copy[i].request == 0) | |
700 | continue; | |
701 | ||
702 | /* Grab a request slot and copy shadow state into it. */ | |
703 | req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); | |
704 | *req = copy[i].req; | |
705 | ||
706 | /* We get a new request id, and must reset the shadow state. */ | |
707 | req->id = get_id_from_freelist(info); | |
708 | memcpy(&info->shadow[req->id], ©[i], sizeof(copy[i])); | |
709 | ||
710 | /* Rewrite any grant references invalidated by susp/resume. */ | |
711 | for (j = 0; j < req->nr_segments; j++) | |
712 | gnttab_grant_foreign_access_ref( | |
713 | req->seg[j].gref, | |
714 | info->xbdev->otherend_id, | |
715 | pfn_to_mfn(info->shadow[req->id].frame[j]), | |
716 | rq_data_dir( | |
717 | (struct request *) | |
718 | info->shadow[req->id].request)); | |
719 | info->shadow[req->id].req = *req; | |
720 | ||
721 | info->ring.req_prod_pvt++; | |
722 | } | |
723 | ||
724 | kfree(copy); | |
725 | ||
726 | xenbus_switch_state(info->xbdev, XenbusStateConnected); | |
727 | ||
728 | spin_lock_irq(&blkif_io_lock); | |
729 | ||
730 | /* Now safe for us to use the shared ring */ | |
731 | info->connected = BLKIF_STATE_CONNECTED; | |
732 | ||
733 | /* Send off requeued requests */ | |
734 | flush_requests(info); | |
735 | ||
736 | /* Kick any other new requests queued since we resumed */ | |
737 | kick_pending_request_queues(info); | |
738 | ||
739 | spin_unlock_irq(&blkif_io_lock); | |
740 | ||
741 | return 0; | |
742 | } | |
743 | ||
744 | /** | |
745 | * We are reconnecting to the backend, due to a suspend/resume, or a backend | |
746 | * driver restart. We tear down our blkif structure and recreate it, but | |
747 | * leave the device-layer structures intact so that this is transparent to the | |
748 | * rest of the kernel. | |
749 | */ | |
750 | static int blkfront_resume(struct xenbus_device *dev) | |
751 | { | |
752 | struct blkfront_info *info = dev->dev.driver_data; | |
753 | int err; | |
754 | ||
755 | dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); | |
756 | ||
757 | blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); | |
758 | ||
759 | err = talk_to_backend(dev, info); | |
760 | if (info->connected == BLKIF_STATE_SUSPENDED && !err) | |
761 | err = blkif_recover(info); | |
762 | ||
763 | return err; | |
764 | } | |
765 | ||
766 | ||
767 | /* | |
768 | * Invoked when the backend is finally 'ready' (and has told produced | |
769 | * the details about the physical device - #sectors, size, etc). | |
770 | */ | |
771 | static void blkfront_connect(struct blkfront_info *info) | |
772 | { | |
773 | unsigned long long sectors; | |
774 | unsigned long sector_size; | |
775 | unsigned int binfo; | |
776 | int err; | |
777 | ||
778 | if ((info->connected == BLKIF_STATE_CONNECTED) || | |
779 | (info->connected == BLKIF_STATE_SUSPENDED) ) | |
780 | return; | |
781 | ||
782 | dev_dbg(&info->xbdev->dev, "%s:%s.\n", | |
783 | __func__, info->xbdev->otherend); | |
784 | ||
785 | err = xenbus_gather(XBT_NIL, info->xbdev->otherend, | |
786 | "sectors", "%llu", §ors, | |
787 | "info", "%u", &binfo, | |
788 | "sector-size", "%lu", §or_size, | |
789 | NULL); | |
790 | if (err) { | |
791 | xenbus_dev_fatal(info->xbdev, err, | |
792 | "reading backend fields at %s", | |
793 | info->xbdev->otherend); | |
794 | return; | |
795 | } | |
796 | ||
797 | err = xenbus_gather(XBT_NIL, info->xbdev->otherend, | |
798 | "feature-barrier", "%lu", &info->feature_barrier, | |
799 | NULL); | |
800 | if (err) | |
801 | info->feature_barrier = 0; | |
802 | ||
803 | err = xlvbd_alloc_gendisk(BLKIF_MINOR(info->vdevice), | |
804 | sectors, info->vdevice, | |
805 | binfo, sector_size, info); | |
806 | if (err) { | |
807 | xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", | |
808 | info->xbdev->otherend); | |
809 | return; | |
810 | } | |
811 | ||
812 | xenbus_switch_state(info->xbdev, XenbusStateConnected); | |
813 | ||
814 | /* Kick pending requests. */ | |
815 | spin_lock_irq(&blkif_io_lock); | |
816 | info->connected = BLKIF_STATE_CONNECTED; | |
817 | kick_pending_request_queues(info); | |
818 | spin_unlock_irq(&blkif_io_lock); | |
819 | ||
820 | add_disk(info->gd); | |
821 | } | |
822 | ||
823 | /** | |
824 | * Handle the change of state of the backend to Closing. We must delete our | |
825 | * device-layer structures now, to ensure that writes are flushed through to | |
826 | * the backend. Once is this done, we can switch to Closed in | |
827 | * acknowledgement. | |
828 | */ | |
829 | static void blkfront_closing(struct xenbus_device *dev) | |
830 | { | |
831 | struct blkfront_info *info = dev->dev.driver_data; | |
832 | unsigned long flags; | |
833 | ||
834 | dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename); | |
835 | ||
836 | if (info->rq == NULL) | |
837 | goto out; | |
838 | ||
839 | spin_lock_irqsave(&blkif_io_lock, flags); | |
840 | ||
841 | del_gendisk(info->gd); | |
842 | ||
843 | /* No more blkif_request(). */ | |
844 | blk_stop_queue(info->rq); | |
845 | ||
846 | /* No more gnttab callback work. */ | |
847 | gnttab_cancel_free_callback(&info->callback); | |
848 | spin_unlock_irqrestore(&blkif_io_lock, flags); | |
849 | ||
850 | /* Flush gnttab callback work. Must be done with no locks held. */ | |
851 | flush_scheduled_work(); | |
852 | ||
853 | blk_cleanup_queue(info->rq); | |
854 | info->rq = NULL; | |
855 | ||
856 | out: | |
857 | xenbus_frontend_closed(dev); | |
858 | } | |
859 | ||
860 | /** | |
861 | * Callback received when the backend's state changes. | |
862 | */ | |
863 | static void backend_changed(struct xenbus_device *dev, | |
864 | enum xenbus_state backend_state) | |
865 | { | |
866 | struct blkfront_info *info = dev->dev.driver_data; | |
867 | struct block_device *bd; | |
868 | ||
869 | dev_dbg(&dev->dev, "blkfront:backend_changed.\n"); | |
870 | ||
871 | switch (backend_state) { | |
872 | case XenbusStateInitialising: | |
873 | case XenbusStateInitWait: | |
874 | case XenbusStateInitialised: | |
875 | case XenbusStateUnknown: | |
876 | case XenbusStateClosed: | |
877 | break; | |
878 | ||
879 | case XenbusStateConnected: | |
880 | blkfront_connect(info); | |
881 | break; | |
882 | ||
883 | case XenbusStateClosing: | |
884 | bd = bdget(info->dev); | |
885 | if (bd == NULL) | |
886 | xenbus_dev_fatal(dev, -ENODEV, "bdget failed"); | |
887 | ||
888 | mutex_lock(&bd->bd_mutex); | |
889 | if (info->users > 0) | |
890 | xenbus_dev_error(dev, -EBUSY, | |
891 | "Device in use; refusing to close"); | |
892 | else | |
893 | blkfront_closing(dev); | |
894 | mutex_unlock(&bd->bd_mutex); | |
895 | bdput(bd); | |
896 | break; | |
897 | } | |
898 | } | |
899 | ||
900 | static int blkfront_remove(struct xenbus_device *dev) | |
901 | { | |
902 | struct blkfront_info *info = dev->dev.driver_data; | |
903 | ||
904 | dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename); | |
905 | ||
906 | blkif_free(info, 0); | |
907 | ||
908 | kfree(info); | |
909 | ||
910 | return 0; | |
911 | } | |
912 | ||
913 | static int blkif_open(struct inode *inode, struct file *filep) | |
914 | { | |
915 | struct blkfront_info *info = inode->i_bdev->bd_disk->private_data; | |
916 | info->users++; | |
917 | return 0; | |
918 | } | |
919 | ||
920 | static int blkif_release(struct inode *inode, struct file *filep) | |
921 | { | |
922 | struct blkfront_info *info = inode->i_bdev->bd_disk->private_data; | |
923 | info->users--; | |
924 | if (info->users == 0) { | |
925 | /* Check whether we have been instructed to close. We will | |
926 | have ignored this request initially, as the device was | |
927 | still mounted. */ | |
928 | struct xenbus_device *dev = info->xbdev; | |
929 | enum xenbus_state state = xenbus_read_driver_state(dev->otherend); | |
930 | ||
931 | if (state == XenbusStateClosing) | |
932 | blkfront_closing(dev); | |
933 | } | |
934 | return 0; | |
935 | } | |
936 | ||
937 | static struct block_device_operations xlvbd_block_fops = | |
938 | { | |
939 | .owner = THIS_MODULE, | |
940 | .open = blkif_open, | |
941 | .release = blkif_release, | |
942 | }; | |
943 | ||
944 | ||
945 | static struct xenbus_device_id blkfront_ids[] = { | |
946 | { "vbd" }, | |
947 | { "" } | |
948 | }; | |
949 | ||
950 | static struct xenbus_driver blkfront = { | |
951 | .name = "vbd", | |
952 | .owner = THIS_MODULE, | |
953 | .ids = blkfront_ids, | |
954 | .probe = blkfront_probe, | |
955 | .remove = blkfront_remove, | |
956 | .resume = blkfront_resume, | |
957 | .otherend_changed = backend_changed, | |
958 | }; | |
959 | ||
960 | static int __init xlblk_init(void) | |
961 | { | |
962 | if (!is_running_on_xen()) | |
963 | return -ENODEV; | |
964 | ||
965 | if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { | |
966 | printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", | |
967 | XENVBD_MAJOR, DEV_NAME); | |
968 | return -ENODEV; | |
969 | } | |
970 | ||
971 | return xenbus_register_frontend(&blkfront); | |
972 | } | |
973 | module_init(xlblk_init); | |
974 | ||
975 | ||
976 | static void xlblk_exit(void) | |
977 | { | |
978 | return xenbus_unregister_driver(&blkfront); | |
979 | } | |
980 | module_exit(xlblk_exit); | |
981 | ||
982 | MODULE_DESCRIPTION("Xen virtual block device frontend"); | |
983 | MODULE_LICENSE("GPL"); | |
984 | MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); |