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/blk-mq.h>
41 #include <linux/hdreg.h>
42 #include <linux/cdrom.h>
43 #include <linux/module.h>
44 #include <linux/slab.h>
45 #include <linux/mutex.h>
46 #include <linux/scatterlist.h>
47 #include <linux/bitmap.h>
48 #include <linux/list.h>
49 #include <linux/workqueue.h>
50 #include <linux/sched/mm.h>
51
52 #include <xen/xen.h>
53 #include <xen/xenbus.h>
54 #include <xen/grant_table.h>
55 #include <xen/events.h>
56 #include <xen/page.h>
57 #include <xen/platform_pci.h>
58
59 #include <xen/interface/grant_table.h>
60 #include <xen/interface/io/blkif.h>
61 #include <xen/interface/io/protocols.h>
62
63 #include <asm/xen/hypervisor.h>
64
65 /*
66 * The minimal size of segment supported by the block framework is PAGE_SIZE.
67 * When Linux is using a different page size than Xen, it may not be possible
68 * to put all the data in a single segment.
69 * This can happen when the backend doesn't support indirect descriptor and
70 * therefore the maximum amount of data that a request can carry is
71 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
72 *
73 * Note that we only support one extra request. So the Linux page size
74 * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
75 * 88KB.
76 */
77 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
78
79 enum blkif_state {
80 BLKIF_STATE_DISCONNECTED,
81 BLKIF_STATE_CONNECTED,
82 BLKIF_STATE_SUSPENDED,
83 };
84
85 struct grant {
86 grant_ref_t gref;
87 struct page *page;
88 struct list_head node;
89 };
90
91 enum blk_req_status {
92 REQ_WAITING,
93 REQ_DONE,
94 REQ_ERROR,
95 REQ_EOPNOTSUPP,
96 };
97
98 struct blk_shadow {
99 struct blkif_request req;
100 struct request *request;
101 struct grant **grants_used;
102 struct grant **indirect_grants;
103 struct scatterlist *sg;
104 unsigned int num_sg;
105 enum blk_req_status status;
106
107 #define NO_ASSOCIATED_ID ~0UL
108 /*
109 * Id of the sibling if we ever need 2 requests when handling a
110 * block I/O request
111 */
112 unsigned long associated_id;
113 };
114
115 struct blkif_req {
116 blk_status_t error;
117 };
118
blkif_req(struct request * rq)119 static inline struct blkif_req *blkif_req(struct request *rq)
120 {
121 return blk_mq_rq_to_pdu(rq);
122 }
123
124 static DEFINE_MUTEX(blkfront_mutex);
125 static const struct block_device_operations xlvbd_block_fops;
126 static struct delayed_work blkfront_work;
127 static LIST_HEAD(info_list);
128
129 /*
130 * Maximum number of segments in indirect requests, the actual value used by
131 * the frontend driver is the minimum of this value and the value provided
132 * by the backend driver.
133 */
134
135 static unsigned int xen_blkif_max_segments = 32;
136 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
137 MODULE_PARM_DESC(max_indirect_segments,
138 "Maximum amount of segments in indirect requests (default is 32)");
139
140 static unsigned int xen_blkif_max_queues = 4;
141 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
142 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
143
144 /*
145 * Maximum order of pages to be used for the shared ring between front and
146 * backend, 4KB page granularity is used.
147 */
148 static unsigned int xen_blkif_max_ring_order;
149 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
150 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
151
152 #define BLK_RING_SIZE(info) \
153 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
154
155 /*
156 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
157 * characters are enough. Define to 20 to keep consistent with backend.
158 */
159 #define RINGREF_NAME_LEN (20)
160 /*
161 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
162 */
163 #define QUEUE_NAME_LEN (17)
164
165 /*
166 * Per-ring info.
167 * Every blkfront device can associate with one or more blkfront_ring_info,
168 * depending on how many hardware queues/rings to be used.
169 */
170 struct blkfront_ring_info {
171 /* Lock to protect data in every ring buffer. */
172 spinlock_t ring_lock;
173 struct blkif_front_ring ring;
174 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
175 unsigned int evtchn, irq;
176 struct work_struct work;
177 struct gnttab_free_callback callback;
178 struct list_head indirect_pages;
179 struct list_head grants;
180 unsigned int persistent_gnts_c;
181 unsigned long shadow_free;
182 struct blkfront_info *dev_info;
183 struct blk_shadow shadow[];
184 };
185
186 /*
187 * We have one of these per vbd, whether ide, scsi or 'other'. They
188 * hang in private_data off the gendisk structure. We may end up
189 * putting all kinds of interesting stuff here :-)
190 */
191 struct blkfront_info
192 {
193 struct mutex mutex;
194 struct xenbus_device *xbdev;
195 struct gendisk *gd;
196 u16 sector_size;
197 unsigned int physical_sector_size;
198 int vdevice;
199 blkif_vdev_t handle;
200 enum blkif_state connected;
201 /* Number of pages per ring buffer. */
202 unsigned int nr_ring_pages;
203 struct request_queue *rq;
204 unsigned int feature_flush:1;
205 unsigned int feature_fua:1;
206 unsigned int feature_discard:1;
207 unsigned int feature_secdiscard:1;
208 unsigned int feature_persistent:1;
209 unsigned int discard_granularity;
210 unsigned int discard_alignment;
211 /* Number of 4KB segments handled */
212 unsigned int max_indirect_segments;
213 int is_ready;
214 struct blk_mq_tag_set tag_set;
215 struct blkfront_ring_info *rinfo;
216 unsigned int nr_rings;
217 unsigned int rinfo_size;
218 /* Save uncomplete reqs and bios for migration. */
219 struct list_head requests;
220 struct bio_list bio_list;
221 struct list_head info_list;
222 };
223
224 static unsigned int nr_minors;
225 static unsigned long *minors;
226 static DEFINE_SPINLOCK(minor_lock);
227
228 #define GRANT_INVALID_REF 0
229
230 #define PARTS_PER_DISK 16
231 #define PARTS_PER_EXT_DISK 256
232
233 #define BLKIF_MAJOR(dev) ((dev)>>8)
234 #define BLKIF_MINOR(dev) ((dev) & 0xff)
235
236 #define EXT_SHIFT 28
237 #define EXTENDED (1<<EXT_SHIFT)
238 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
239 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
240 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
241 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
242 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
243 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
244
245 #define DEV_NAME "xvd" /* name in /dev */
246
247 /*
248 * Grants are always the same size as a Xen page (i.e 4KB).
249 * A physical segment is always the same size as a Linux page.
250 * Number of grants per physical segment
251 */
252 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
253
254 #define GRANTS_PER_INDIRECT_FRAME \
255 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
256
257 #define INDIRECT_GREFS(_grants) \
258 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
259
260 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
261 static void blkfront_gather_backend_features(struct blkfront_info *info);
262 static int negotiate_mq(struct blkfront_info *info);
263
264 #define for_each_rinfo(info, ptr, idx) \
265 for ((ptr) = (info)->rinfo, (idx) = 0; \
266 (idx) < (info)->nr_rings; \
267 (idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size)
268
269 static inline struct blkfront_ring_info *
get_rinfo(const struct blkfront_info * info,unsigned int i)270 get_rinfo(const struct blkfront_info *info, unsigned int i)
271 {
272 BUG_ON(i >= info->nr_rings);
273 return (void *)info->rinfo + i * info->rinfo_size;
274 }
275
get_id_from_freelist(struct blkfront_ring_info * rinfo)276 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
277 {
278 unsigned long free = rinfo->shadow_free;
279
280 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
281 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
282 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
283 return free;
284 }
285
add_id_to_freelist(struct blkfront_ring_info * rinfo,unsigned long id)286 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
287 unsigned long id)
288 {
289 if (rinfo->shadow[id].req.u.rw.id != id)
290 return -EINVAL;
291 if (rinfo->shadow[id].request == NULL)
292 return -EINVAL;
293 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
294 rinfo->shadow[id].request = NULL;
295 rinfo->shadow_free = id;
296 return 0;
297 }
298
fill_grant_buffer(struct blkfront_ring_info * rinfo,int num)299 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
300 {
301 struct blkfront_info *info = rinfo->dev_info;
302 struct page *granted_page;
303 struct grant *gnt_list_entry, *n;
304 int i = 0;
305
306 while (i < num) {
307 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
308 if (!gnt_list_entry)
309 goto out_of_memory;
310
311 if (info->feature_persistent) {
312 granted_page = alloc_page(GFP_NOIO);
313 if (!granted_page) {
314 kfree(gnt_list_entry);
315 goto out_of_memory;
316 }
317 gnt_list_entry->page = granted_page;
318 }
319
320 gnt_list_entry->gref = GRANT_INVALID_REF;
321 list_add(&gnt_list_entry->node, &rinfo->grants);
322 i++;
323 }
324
325 return 0;
326
327 out_of_memory:
328 list_for_each_entry_safe(gnt_list_entry, n,
329 &rinfo->grants, node) {
330 list_del(&gnt_list_entry->node);
331 if (info->feature_persistent)
332 __free_page(gnt_list_entry->page);
333 kfree(gnt_list_entry);
334 i--;
335 }
336 BUG_ON(i != 0);
337 return -ENOMEM;
338 }
339
get_free_grant(struct blkfront_ring_info * rinfo)340 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
341 {
342 struct grant *gnt_list_entry;
343
344 BUG_ON(list_empty(&rinfo->grants));
345 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
346 node);
347 list_del(&gnt_list_entry->node);
348
349 if (gnt_list_entry->gref != GRANT_INVALID_REF)
350 rinfo->persistent_gnts_c--;
351
352 return gnt_list_entry;
353 }
354
grant_foreign_access(const struct grant * gnt_list_entry,const struct blkfront_info * info)355 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
356 const struct blkfront_info *info)
357 {
358 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
359 info->xbdev->otherend_id,
360 gnt_list_entry->page,
361 0);
362 }
363
get_grant(grant_ref_t * gref_head,unsigned long gfn,struct blkfront_ring_info * rinfo)364 static struct grant *get_grant(grant_ref_t *gref_head,
365 unsigned long gfn,
366 struct blkfront_ring_info *rinfo)
367 {
368 struct grant *gnt_list_entry = get_free_grant(rinfo);
369 struct blkfront_info *info = rinfo->dev_info;
370
371 if (gnt_list_entry->gref != GRANT_INVALID_REF)
372 return gnt_list_entry;
373
374 /* Assign a gref to this page */
375 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
376 BUG_ON(gnt_list_entry->gref == -ENOSPC);
377 if (info->feature_persistent)
378 grant_foreign_access(gnt_list_entry, info);
379 else {
380 /* Grant access to the GFN passed by the caller */
381 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
382 info->xbdev->otherend_id,
383 gfn, 0);
384 }
385
386 return gnt_list_entry;
387 }
388
get_indirect_grant(grant_ref_t * gref_head,struct blkfront_ring_info * rinfo)389 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
390 struct blkfront_ring_info *rinfo)
391 {
392 struct grant *gnt_list_entry = get_free_grant(rinfo);
393 struct blkfront_info *info = rinfo->dev_info;
394
395 if (gnt_list_entry->gref != GRANT_INVALID_REF)
396 return gnt_list_entry;
397
398 /* Assign a gref to this page */
399 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
400 BUG_ON(gnt_list_entry->gref == -ENOSPC);
401 if (!info->feature_persistent) {
402 struct page *indirect_page;
403
404 /* Fetch a pre-allocated page to use for indirect grefs */
405 BUG_ON(list_empty(&rinfo->indirect_pages));
406 indirect_page = list_first_entry(&rinfo->indirect_pages,
407 struct page, lru);
408 list_del(&indirect_page->lru);
409 gnt_list_entry->page = indirect_page;
410 }
411 grant_foreign_access(gnt_list_entry, info);
412
413 return gnt_list_entry;
414 }
415
op_name(int op)416 static const char *op_name(int op)
417 {
418 static const char *const names[] = {
419 [BLKIF_OP_READ] = "read",
420 [BLKIF_OP_WRITE] = "write",
421 [BLKIF_OP_WRITE_BARRIER] = "barrier",
422 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
423 [BLKIF_OP_DISCARD] = "discard" };
424
425 if (op < 0 || op >= ARRAY_SIZE(names))
426 return "unknown";
427
428 if (!names[op])
429 return "reserved";
430
431 return names[op];
432 }
xlbd_reserve_minors(unsigned int minor,unsigned int nr)433 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
434 {
435 unsigned int end = minor + nr;
436 int rc;
437
438 if (end > nr_minors) {
439 unsigned long *bitmap, *old;
440
441 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
442 GFP_KERNEL);
443 if (bitmap == NULL)
444 return -ENOMEM;
445
446 spin_lock(&minor_lock);
447 if (end > nr_minors) {
448 old = minors;
449 memcpy(bitmap, minors,
450 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
451 minors = bitmap;
452 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
453 } else
454 old = bitmap;
455 spin_unlock(&minor_lock);
456 kfree(old);
457 }
458
459 spin_lock(&minor_lock);
460 if (find_next_bit(minors, end, minor) >= end) {
461 bitmap_set(minors, minor, nr);
462 rc = 0;
463 } else
464 rc = -EBUSY;
465 spin_unlock(&minor_lock);
466
467 return rc;
468 }
469
xlbd_release_minors(unsigned int minor,unsigned int nr)470 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
471 {
472 unsigned int end = minor + nr;
473
474 BUG_ON(end > nr_minors);
475 spin_lock(&minor_lock);
476 bitmap_clear(minors, minor, nr);
477 spin_unlock(&minor_lock);
478 }
479
blkif_restart_queue_callback(void * arg)480 static void blkif_restart_queue_callback(void *arg)
481 {
482 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
483 schedule_work(&rinfo->work);
484 }
485
blkif_getgeo(struct block_device * bd,struct hd_geometry * hg)486 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
487 {
488 /* We don't have real geometry info, but let's at least return
489 values consistent with the size of the device */
490 sector_t nsect = get_capacity(bd->bd_disk);
491 sector_t cylinders = nsect;
492
493 hg->heads = 0xff;
494 hg->sectors = 0x3f;
495 sector_div(cylinders, hg->heads * hg->sectors);
496 hg->cylinders = cylinders;
497 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
498 hg->cylinders = 0xffff;
499 return 0;
500 }
501
blkif_ioctl(struct block_device * bdev,fmode_t mode,unsigned command,unsigned long argument)502 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
503 unsigned command, unsigned long argument)
504 {
505 struct blkfront_info *info = bdev->bd_disk->private_data;
506 int i;
507
508 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
509 command, (long)argument);
510
511 switch (command) {
512 case CDROMMULTISESSION:
513 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
514 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
515 if (put_user(0, (char __user *)(argument + i)))
516 return -EFAULT;
517 return 0;
518
519 case CDROM_GET_CAPABILITY: {
520 struct gendisk *gd = info->gd;
521 if (gd->flags & GENHD_FL_CD)
522 return 0;
523 return -EINVAL;
524 }
525
526 default:
527 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
528 command);*/
529 return -EINVAL; /* same return as native Linux */
530 }
531
532 return 0;
533 }
534
blkif_ring_get_request(struct blkfront_ring_info * rinfo,struct request * req,struct blkif_request ** ring_req)535 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
536 struct request *req,
537 struct blkif_request **ring_req)
538 {
539 unsigned long id;
540
541 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
542 rinfo->ring.req_prod_pvt++;
543
544 id = get_id_from_freelist(rinfo);
545 rinfo->shadow[id].request = req;
546 rinfo->shadow[id].status = REQ_WAITING;
547 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
548
549 (*ring_req)->u.rw.id = id;
550
551 return id;
552 }
553
blkif_queue_discard_req(struct request * req,struct blkfront_ring_info * rinfo)554 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
555 {
556 struct blkfront_info *info = rinfo->dev_info;
557 struct blkif_request *ring_req;
558 unsigned long id;
559
560 /* Fill out a communications ring structure. */
561 id = blkif_ring_get_request(rinfo, req, &ring_req);
562
563 ring_req->operation = BLKIF_OP_DISCARD;
564 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
565 ring_req->u.discard.id = id;
566 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
567 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
568 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
569 else
570 ring_req->u.discard.flag = 0;
571
572 /* Keep a private copy so we can reissue requests when recovering. */
573 rinfo->shadow[id].req = *ring_req;
574
575 return 0;
576 }
577
578 struct setup_rw_req {
579 unsigned int grant_idx;
580 struct blkif_request_segment *segments;
581 struct blkfront_ring_info *rinfo;
582 struct blkif_request *ring_req;
583 grant_ref_t gref_head;
584 unsigned int id;
585 /* Only used when persistent grant is used and it's a read request */
586 bool need_copy;
587 unsigned int bvec_off;
588 char *bvec_data;
589
590 bool require_extra_req;
591 struct blkif_request *extra_ring_req;
592 };
593
blkif_setup_rw_req_grant(unsigned long gfn,unsigned int offset,unsigned int len,void * data)594 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
595 unsigned int len, void *data)
596 {
597 struct setup_rw_req *setup = data;
598 int n, ref;
599 struct grant *gnt_list_entry;
600 unsigned int fsect, lsect;
601 /* Convenient aliases */
602 unsigned int grant_idx = setup->grant_idx;
603 struct blkif_request *ring_req = setup->ring_req;
604 struct blkfront_ring_info *rinfo = setup->rinfo;
605 /*
606 * We always use the shadow of the first request to store the list
607 * of grant associated to the block I/O request. This made the
608 * completion more easy to handle even if the block I/O request is
609 * split.
610 */
611 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
612
613 if (unlikely(setup->require_extra_req &&
614 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
615 /*
616 * We are using the second request, setup grant_idx
617 * to be the index of the segment array.
618 */
619 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
620 ring_req = setup->extra_ring_req;
621 }
622
623 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
624 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
625 if (setup->segments)
626 kunmap_atomic(setup->segments);
627
628 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
629 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
630 shadow->indirect_grants[n] = gnt_list_entry;
631 setup->segments = kmap_atomic(gnt_list_entry->page);
632 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
633 }
634
635 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
636 ref = gnt_list_entry->gref;
637 /*
638 * All the grants are stored in the shadow of the first
639 * request. Therefore we have to use the global index.
640 */
641 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
642
643 if (setup->need_copy) {
644 void *shared_data;
645
646 shared_data = kmap_atomic(gnt_list_entry->page);
647 /*
648 * this does not wipe data stored outside the
649 * range sg->offset..sg->offset+sg->length.
650 * Therefore, blkback *could* see data from
651 * previous requests. This is OK as long as
652 * persistent grants are shared with just one
653 * domain. It may need refactoring if this
654 * changes
655 */
656 memcpy(shared_data + offset,
657 setup->bvec_data + setup->bvec_off,
658 len);
659
660 kunmap_atomic(shared_data);
661 setup->bvec_off += len;
662 }
663
664 fsect = offset >> 9;
665 lsect = fsect + (len >> 9) - 1;
666 if (ring_req->operation != BLKIF_OP_INDIRECT) {
667 ring_req->u.rw.seg[grant_idx] =
668 (struct blkif_request_segment) {
669 .gref = ref,
670 .first_sect = fsect,
671 .last_sect = lsect };
672 } else {
673 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
674 (struct blkif_request_segment) {
675 .gref = ref,
676 .first_sect = fsect,
677 .last_sect = lsect };
678 }
679
680 (setup->grant_idx)++;
681 }
682
blkif_setup_extra_req(struct blkif_request * first,struct blkif_request * second)683 static void blkif_setup_extra_req(struct blkif_request *first,
684 struct blkif_request *second)
685 {
686 uint16_t nr_segments = first->u.rw.nr_segments;
687
688 /*
689 * The second request is only present when the first request uses
690 * all its segments. It's always the continuity of the first one.
691 */
692 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
693
694 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
695 second->u.rw.sector_number = first->u.rw.sector_number +
696 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
697
698 second->u.rw.handle = first->u.rw.handle;
699 second->operation = first->operation;
700 }
701
blkif_queue_rw_req(struct request * req,struct blkfront_ring_info * rinfo)702 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
703 {
704 struct blkfront_info *info = rinfo->dev_info;
705 struct blkif_request *ring_req, *extra_ring_req = NULL;
706 unsigned long id, extra_id = NO_ASSOCIATED_ID;
707 bool require_extra_req = false;
708 int i;
709 struct setup_rw_req setup = {
710 .grant_idx = 0,
711 .segments = NULL,
712 .rinfo = rinfo,
713 .need_copy = rq_data_dir(req) && info->feature_persistent,
714 };
715
716 /*
717 * Used to store if we are able to queue the request by just using
718 * existing persistent grants, or if we have to get new grants,
719 * as there are not sufficiently many free.
720 */
721 bool new_persistent_gnts = false;
722 struct scatterlist *sg;
723 int num_sg, max_grefs, num_grant;
724
725 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
726 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
727 /*
728 * If we are using indirect segments we need to account
729 * for the indirect grefs used in the request.
730 */
731 max_grefs += INDIRECT_GREFS(max_grefs);
732
733 /* Check if we have enough persistent grants to allocate a requests */
734 if (rinfo->persistent_gnts_c < max_grefs) {
735 new_persistent_gnts = true;
736
737 if (gnttab_alloc_grant_references(
738 max_grefs - rinfo->persistent_gnts_c,
739 &setup.gref_head) < 0) {
740 gnttab_request_free_callback(
741 &rinfo->callback,
742 blkif_restart_queue_callback,
743 rinfo,
744 max_grefs - rinfo->persistent_gnts_c);
745 return 1;
746 }
747 }
748
749 /* Fill out a communications ring structure. */
750 id = blkif_ring_get_request(rinfo, req, &ring_req);
751
752 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
753 num_grant = 0;
754 /* Calculate the number of grant used */
755 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
756 num_grant += gnttab_count_grant(sg->offset, sg->length);
757
758 require_extra_req = info->max_indirect_segments == 0 &&
759 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
760 BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
761
762 rinfo->shadow[id].num_sg = num_sg;
763 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
764 likely(!require_extra_req)) {
765 /*
766 * The indirect operation can only be a BLKIF_OP_READ or
767 * BLKIF_OP_WRITE
768 */
769 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
770 ring_req->operation = BLKIF_OP_INDIRECT;
771 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
772 BLKIF_OP_WRITE : BLKIF_OP_READ;
773 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
774 ring_req->u.indirect.handle = info->handle;
775 ring_req->u.indirect.nr_segments = num_grant;
776 } else {
777 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
778 ring_req->u.rw.handle = info->handle;
779 ring_req->operation = rq_data_dir(req) ?
780 BLKIF_OP_WRITE : BLKIF_OP_READ;
781 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
782 /*
783 * Ideally we can do an unordered flush-to-disk.
784 * In case the backend onlysupports barriers, use that.
785 * A barrier request a superset of FUA, so we can
786 * implement it the same way. (It's also a FLUSH+FUA,
787 * since it is guaranteed ordered WRT previous writes.)
788 */
789 if (info->feature_flush && info->feature_fua)
790 ring_req->operation =
791 BLKIF_OP_WRITE_BARRIER;
792 else if (info->feature_flush)
793 ring_req->operation =
794 BLKIF_OP_FLUSH_DISKCACHE;
795 else
796 ring_req->operation = 0;
797 }
798 ring_req->u.rw.nr_segments = num_grant;
799 if (unlikely(require_extra_req)) {
800 extra_id = blkif_ring_get_request(rinfo, req,
801 &extra_ring_req);
802 /*
803 * Only the first request contains the scatter-gather
804 * list.
805 */
806 rinfo->shadow[extra_id].num_sg = 0;
807
808 blkif_setup_extra_req(ring_req, extra_ring_req);
809
810 /* Link the 2 requests together */
811 rinfo->shadow[extra_id].associated_id = id;
812 rinfo->shadow[id].associated_id = extra_id;
813 }
814 }
815
816 setup.ring_req = ring_req;
817 setup.id = id;
818
819 setup.require_extra_req = require_extra_req;
820 if (unlikely(require_extra_req))
821 setup.extra_ring_req = extra_ring_req;
822
823 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
824 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
825
826 if (setup.need_copy) {
827 setup.bvec_off = sg->offset;
828 setup.bvec_data = kmap_atomic(sg_page(sg));
829 }
830
831 gnttab_foreach_grant_in_range(sg_page(sg),
832 sg->offset,
833 sg->length,
834 blkif_setup_rw_req_grant,
835 &setup);
836
837 if (setup.need_copy)
838 kunmap_atomic(setup.bvec_data);
839 }
840 if (setup.segments)
841 kunmap_atomic(setup.segments);
842
843 /* Keep a private copy so we can reissue requests when recovering. */
844 rinfo->shadow[id].req = *ring_req;
845 if (unlikely(require_extra_req))
846 rinfo->shadow[extra_id].req = *extra_ring_req;
847
848 if (new_persistent_gnts)
849 gnttab_free_grant_references(setup.gref_head);
850
851 return 0;
852 }
853
854 /*
855 * Generate a Xen blkfront IO request from a blk layer request. Reads
856 * and writes are handled as expected.
857 *
858 * @req: a request struct
859 */
blkif_queue_request(struct request * req,struct blkfront_ring_info * rinfo)860 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
861 {
862 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
863 return 1;
864
865 if (unlikely(req_op(req) == REQ_OP_DISCARD ||
866 req_op(req) == REQ_OP_SECURE_ERASE))
867 return blkif_queue_discard_req(req, rinfo);
868 else
869 return blkif_queue_rw_req(req, rinfo);
870 }
871
flush_requests(struct blkfront_ring_info * rinfo)872 static inline void flush_requests(struct blkfront_ring_info *rinfo)
873 {
874 int notify;
875
876 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
877
878 if (notify)
879 notify_remote_via_irq(rinfo->irq);
880 }
881
blkif_request_flush_invalid(struct request * req,struct blkfront_info * info)882 static inline bool blkif_request_flush_invalid(struct request *req,
883 struct blkfront_info *info)
884 {
885 return (blk_rq_is_passthrough(req) ||
886 ((req_op(req) == REQ_OP_FLUSH) &&
887 !info->feature_flush) ||
888 ((req->cmd_flags & REQ_FUA) &&
889 !info->feature_fua));
890 }
891
blkif_queue_rq(struct blk_mq_hw_ctx * hctx,const struct blk_mq_queue_data * qd)892 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
893 const struct blk_mq_queue_data *qd)
894 {
895 unsigned long flags;
896 int qid = hctx->queue_num;
897 struct blkfront_info *info = hctx->queue->queuedata;
898 struct blkfront_ring_info *rinfo = NULL;
899
900 rinfo = get_rinfo(info, qid);
901 blk_mq_start_request(qd->rq);
902 spin_lock_irqsave(&rinfo->ring_lock, flags);
903 if (RING_FULL(&rinfo->ring))
904 goto out_busy;
905
906 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
907 goto out_err;
908
909 if (blkif_queue_request(qd->rq, rinfo))
910 goto out_busy;
911
912 flush_requests(rinfo);
913 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
914 return BLK_STS_OK;
915
916 out_err:
917 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
918 return BLK_STS_IOERR;
919
920 out_busy:
921 blk_mq_stop_hw_queue(hctx);
922 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
923 return BLK_STS_DEV_RESOURCE;
924 }
925
blkif_complete_rq(struct request * rq)926 static void blkif_complete_rq(struct request *rq)
927 {
928 blk_mq_end_request(rq, blkif_req(rq)->error);
929 }
930
931 static const struct blk_mq_ops blkfront_mq_ops = {
932 .queue_rq = blkif_queue_rq,
933 .complete = blkif_complete_rq,
934 };
935
blkif_set_queue_limits(struct blkfront_info * info)936 static void blkif_set_queue_limits(struct blkfront_info *info)
937 {
938 struct request_queue *rq = info->rq;
939 struct gendisk *gd = info->gd;
940 unsigned int segments = info->max_indirect_segments ? :
941 BLKIF_MAX_SEGMENTS_PER_REQUEST;
942
943 blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
944
945 if (info->feature_discard) {
946 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
947 blk_queue_max_discard_sectors(rq, get_capacity(gd));
948 rq->limits.discard_granularity = info->discard_granularity ?:
949 info->physical_sector_size;
950 rq->limits.discard_alignment = info->discard_alignment;
951 if (info->feature_secdiscard)
952 blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
953 }
954
955 /* Hard sector size and max sectors impersonate the equiv. hardware. */
956 blk_queue_logical_block_size(rq, info->sector_size);
957 blk_queue_physical_block_size(rq, info->physical_sector_size);
958 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
959
960 /* Each segment in a request is up to an aligned page in size. */
961 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
962 blk_queue_max_segment_size(rq, PAGE_SIZE);
963
964 /* Ensure a merged request will fit in a single I/O ring slot. */
965 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
966
967 /* Make sure buffer addresses are sector-aligned. */
968 blk_queue_dma_alignment(rq, 511);
969 }
970
xlvbd_init_blk_queue(struct gendisk * gd,u16 sector_size,unsigned int physical_sector_size)971 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
972 unsigned int physical_sector_size)
973 {
974 struct request_queue *rq;
975 struct blkfront_info *info = gd->private_data;
976
977 memset(&info->tag_set, 0, sizeof(info->tag_set));
978 info->tag_set.ops = &blkfront_mq_ops;
979 info->tag_set.nr_hw_queues = info->nr_rings;
980 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
981 /*
982 * When indirect descriptior is not supported, the I/O request
983 * will be split between multiple request in the ring.
984 * To avoid problems when sending the request, divide by
985 * 2 the depth of the queue.
986 */
987 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
988 } else
989 info->tag_set.queue_depth = BLK_RING_SIZE(info);
990 info->tag_set.numa_node = NUMA_NO_NODE;
991 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
992 info->tag_set.cmd_size = sizeof(struct blkif_req);
993 info->tag_set.driver_data = info;
994
995 if (blk_mq_alloc_tag_set(&info->tag_set))
996 return -EINVAL;
997 rq = blk_mq_init_queue(&info->tag_set);
998 if (IS_ERR(rq)) {
999 blk_mq_free_tag_set(&info->tag_set);
1000 return PTR_ERR(rq);
1001 }
1002
1003 rq->queuedata = info;
1004 info->rq = gd->queue = rq;
1005 info->gd = gd;
1006 info->sector_size = sector_size;
1007 info->physical_sector_size = physical_sector_size;
1008 blkif_set_queue_limits(info);
1009
1010 return 0;
1011 }
1012
flush_info(struct blkfront_info * info)1013 static const char *flush_info(struct blkfront_info *info)
1014 {
1015 if (info->feature_flush && info->feature_fua)
1016 return "barrier: enabled;";
1017 else if (info->feature_flush)
1018 return "flush diskcache: enabled;";
1019 else
1020 return "barrier or flush: disabled;";
1021 }
1022
xlvbd_flush(struct blkfront_info * info)1023 static void xlvbd_flush(struct blkfront_info *info)
1024 {
1025 blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
1026 info->feature_fua ? true : false);
1027 pr_info("blkfront: %s: %s %s %s %s %s\n",
1028 info->gd->disk_name, flush_info(info),
1029 "persistent grants:", info->feature_persistent ?
1030 "enabled;" : "disabled;", "indirect descriptors:",
1031 info->max_indirect_segments ? "enabled;" : "disabled;");
1032 }
1033
xen_translate_vdev(int vdevice,int * minor,unsigned int * offset)1034 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1035 {
1036 int major;
1037 major = BLKIF_MAJOR(vdevice);
1038 *minor = BLKIF_MINOR(vdevice);
1039 switch (major) {
1040 case XEN_IDE0_MAJOR:
1041 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1042 *minor = ((*minor / 64) * PARTS_PER_DISK) +
1043 EMULATED_HD_DISK_MINOR_OFFSET;
1044 break;
1045 case XEN_IDE1_MAJOR:
1046 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1047 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1048 EMULATED_HD_DISK_MINOR_OFFSET;
1049 break;
1050 case XEN_SCSI_DISK0_MAJOR:
1051 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1052 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1053 break;
1054 case XEN_SCSI_DISK1_MAJOR:
1055 case XEN_SCSI_DISK2_MAJOR:
1056 case XEN_SCSI_DISK3_MAJOR:
1057 case XEN_SCSI_DISK4_MAJOR:
1058 case XEN_SCSI_DISK5_MAJOR:
1059 case XEN_SCSI_DISK6_MAJOR:
1060 case XEN_SCSI_DISK7_MAJOR:
1061 *offset = (*minor / PARTS_PER_DISK) +
1062 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1063 EMULATED_SD_DISK_NAME_OFFSET;
1064 *minor = *minor +
1065 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1066 EMULATED_SD_DISK_MINOR_OFFSET;
1067 break;
1068 case XEN_SCSI_DISK8_MAJOR:
1069 case XEN_SCSI_DISK9_MAJOR:
1070 case XEN_SCSI_DISK10_MAJOR:
1071 case XEN_SCSI_DISK11_MAJOR:
1072 case XEN_SCSI_DISK12_MAJOR:
1073 case XEN_SCSI_DISK13_MAJOR:
1074 case XEN_SCSI_DISK14_MAJOR:
1075 case XEN_SCSI_DISK15_MAJOR:
1076 *offset = (*minor / PARTS_PER_DISK) +
1077 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1078 EMULATED_SD_DISK_NAME_OFFSET;
1079 *minor = *minor +
1080 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1081 EMULATED_SD_DISK_MINOR_OFFSET;
1082 break;
1083 case XENVBD_MAJOR:
1084 *offset = *minor / PARTS_PER_DISK;
1085 break;
1086 default:
1087 printk(KERN_WARNING "blkfront: your disk configuration is "
1088 "incorrect, please use an xvd device instead\n");
1089 return -ENODEV;
1090 }
1091 return 0;
1092 }
1093
encode_disk_name(char * ptr,unsigned int n)1094 static char *encode_disk_name(char *ptr, unsigned int n)
1095 {
1096 if (n >= 26)
1097 ptr = encode_disk_name(ptr, n / 26 - 1);
1098 *ptr = 'a' + n % 26;
1099 return ptr + 1;
1100 }
1101
xlvbd_alloc_gendisk(blkif_sector_t capacity,struct blkfront_info * info,u16 vdisk_info,u16 sector_size,unsigned int physical_sector_size)1102 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1103 struct blkfront_info *info,
1104 u16 vdisk_info, u16 sector_size,
1105 unsigned int physical_sector_size)
1106 {
1107 struct gendisk *gd;
1108 int nr_minors = 1;
1109 int err;
1110 unsigned int offset;
1111 int minor;
1112 int nr_parts;
1113 char *ptr;
1114
1115 BUG_ON(info->gd != NULL);
1116 BUG_ON(info->rq != NULL);
1117
1118 if ((info->vdevice>>EXT_SHIFT) > 1) {
1119 /* this is above the extended range; something is wrong */
1120 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1121 return -ENODEV;
1122 }
1123
1124 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1125 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1126 if (err)
1127 return err;
1128 nr_parts = PARTS_PER_DISK;
1129 } else {
1130 minor = BLKIF_MINOR_EXT(info->vdevice);
1131 nr_parts = PARTS_PER_EXT_DISK;
1132 offset = minor / nr_parts;
1133 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1134 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1135 "emulated IDE disks,\n\t choose an xvd device name"
1136 "from xvde on\n", info->vdevice);
1137 }
1138 if (minor >> MINORBITS) {
1139 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1140 info->vdevice, minor);
1141 return -ENODEV;
1142 }
1143
1144 if ((minor % nr_parts) == 0)
1145 nr_minors = nr_parts;
1146
1147 err = xlbd_reserve_minors(minor, nr_minors);
1148 if (err)
1149 goto out;
1150 err = -ENODEV;
1151
1152 gd = alloc_disk(nr_minors);
1153 if (gd == NULL)
1154 goto release;
1155
1156 strcpy(gd->disk_name, DEV_NAME);
1157 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1158 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1159 if (nr_minors > 1)
1160 *ptr = 0;
1161 else
1162 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1163 "%d", minor & (nr_parts - 1));
1164
1165 gd->major = XENVBD_MAJOR;
1166 gd->first_minor = minor;
1167 gd->fops = &xlvbd_block_fops;
1168 gd->private_data = info;
1169 set_capacity(gd, capacity);
1170
1171 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
1172 del_gendisk(gd);
1173 goto release;
1174 }
1175
1176 xlvbd_flush(info);
1177
1178 if (vdisk_info & VDISK_READONLY)
1179 set_disk_ro(gd, 1);
1180
1181 if (vdisk_info & VDISK_REMOVABLE)
1182 gd->flags |= GENHD_FL_REMOVABLE;
1183
1184 if (vdisk_info & VDISK_CDROM)
1185 gd->flags |= GENHD_FL_CD;
1186
1187 return 0;
1188
1189 release:
1190 xlbd_release_minors(minor, nr_minors);
1191 out:
1192 return err;
1193 }
1194
xlvbd_release_gendisk(struct blkfront_info * info)1195 static void xlvbd_release_gendisk(struct blkfront_info *info)
1196 {
1197 unsigned int minor, nr_minors, i;
1198 struct blkfront_ring_info *rinfo;
1199
1200 if (info->rq == NULL)
1201 return;
1202
1203 /* No more blkif_request(). */
1204 blk_mq_stop_hw_queues(info->rq);
1205
1206 for_each_rinfo(info, rinfo, i) {
1207 /* No more gnttab callback work. */
1208 gnttab_cancel_free_callback(&rinfo->callback);
1209
1210 /* Flush gnttab callback work. Must be done with no locks held. */
1211 flush_work(&rinfo->work);
1212 }
1213
1214 del_gendisk(info->gd);
1215
1216 minor = info->gd->first_minor;
1217 nr_minors = info->gd->minors;
1218 xlbd_release_minors(minor, nr_minors);
1219
1220 blk_cleanup_queue(info->rq);
1221 blk_mq_free_tag_set(&info->tag_set);
1222 info->rq = NULL;
1223
1224 put_disk(info->gd);
1225 info->gd = NULL;
1226 }
1227
1228 /* Already hold rinfo->ring_lock. */
kick_pending_request_queues_locked(struct blkfront_ring_info * rinfo)1229 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1230 {
1231 if (!RING_FULL(&rinfo->ring))
1232 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1233 }
1234
kick_pending_request_queues(struct blkfront_ring_info * rinfo)1235 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1236 {
1237 unsigned long flags;
1238
1239 spin_lock_irqsave(&rinfo->ring_lock, flags);
1240 kick_pending_request_queues_locked(rinfo);
1241 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1242 }
1243
blkif_restart_queue(struct work_struct * work)1244 static void blkif_restart_queue(struct work_struct *work)
1245 {
1246 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1247
1248 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1249 kick_pending_request_queues(rinfo);
1250 }
1251
blkif_free_ring(struct blkfront_ring_info * rinfo)1252 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1253 {
1254 struct grant *persistent_gnt, *n;
1255 struct blkfront_info *info = rinfo->dev_info;
1256 int i, j, segs;
1257
1258 /*
1259 * Remove indirect pages, this only happens when using indirect
1260 * descriptors but not persistent grants
1261 */
1262 if (!list_empty(&rinfo->indirect_pages)) {
1263 struct page *indirect_page, *n;
1264
1265 BUG_ON(info->feature_persistent);
1266 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1267 list_del(&indirect_page->lru);
1268 __free_page(indirect_page);
1269 }
1270 }
1271
1272 /* Remove all persistent grants. */
1273 if (!list_empty(&rinfo->grants)) {
1274 list_for_each_entry_safe(persistent_gnt, n,
1275 &rinfo->grants, node) {
1276 list_del(&persistent_gnt->node);
1277 if (persistent_gnt->gref != GRANT_INVALID_REF) {
1278 gnttab_end_foreign_access(persistent_gnt->gref,
1279 0, 0UL);
1280 rinfo->persistent_gnts_c--;
1281 }
1282 if (info->feature_persistent)
1283 __free_page(persistent_gnt->page);
1284 kfree(persistent_gnt);
1285 }
1286 }
1287 BUG_ON(rinfo->persistent_gnts_c != 0);
1288
1289 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1290 /*
1291 * Clear persistent grants present in requests already
1292 * on the shared ring
1293 */
1294 if (!rinfo->shadow[i].request)
1295 goto free_shadow;
1296
1297 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1298 rinfo->shadow[i].req.u.indirect.nr_segments :
1299 rinfo->shadow[i].req.u.rw.nr_segments;
1300 for (j = 0; j < segs; j++) {
1301 persistent_gnt = rinfo->shadow[i].grants_used[j];
1302 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1303 if (info->feature_persistent)
1304 __free_page(persistent_gnt->page);
1305 kfree(persistent_gnt);
1306 }
1307
1308 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1309 /*
1310 * If this is not an indirect operation don't try to
1311 * free indirect segments
1312 */
1313 goto free_shadow;
1314
1315 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1316 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1317 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1318 __free_page(persistent_gnt->page);
1319 kfree(persistent_gnt);
1320 }
1321
1322 free_shadow:
1323 kvfree(rinfo->shadow[i].grants_used);
1324 rinfo->shadow[i].grants_used = NULL;
1325 kvfree(rinfo->shadow[i].indirect_grants);
1326 rinfo->shadow[i].indirect_grants = NULL;
1327 kvfree(rinfo->shadow[i].sg);
1328 rinfo->shadow[i].sg = NULL;
1329 }
1330
1331 /* No more gnttab callback work. */
1332 gnttab_cancel_free_callback(&rinfo->callback);
1333
1334 /* Flush gnttab callback work. Must be done with no locks held. */
1335 flush_work(&rinfo->work);
1336
1337 /* Free resources associated with old device channel. */
1338 for (i = 0; i < info->nr_ring_pages; i++) {
1339 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1340 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1341 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1342 }
1343 }
1344 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1345 rinfo->ring.sring = NULL;
1346
1347 if (rinfo->irq)
1348 unbind_from_irqhandler(rinfo->irq, rinfo);
1349 rinfo->evtchn = rinfo->irq = 0;
1350 }
1351
blkif_free(struct blkfront_info * info,int suspend)1352 static void blkif_free(struct blkfront_info *info, int suspend)
1353 {
1354 unsigned int i;
1355 struct blkfront_ring_info *rinfo;
1356
1357 /* Prevent new requests being issued until we fix things up. */
1358 info->connected = suspend ?
1359 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1360 /* No more blkif_request(). */
1361 if (info->rq)
1362 blk_mq_stop_hw_queues(info->rq);
1363
1364 for_each_rinfo(info, rinfo, i)
1365 blkif_free_ring(rinfo);
1366
1367 kvfree(info->rinfo);
1368 info->rinfo = NULL;
1369 info->nr_rings = 0;
1370 }
1371
1372 struct copy_from_grant {
1373 const struct blk_shadow *s;
1374 unsigned int grant_idx;
1375 unsigned int bvec_offset;
1376 char *bvec_data;
1377 };
1378
blkif_copy_from_grant(unsigned long gfn,unsigned int offset,unsigned int len,void * data)1379 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1380 unsigned int len, void *data)
1381 {
1382 struct copy_from_grant *info = data;
1383 char *shared_data;
1384 /* Convenient aliases */
1385 const struct blk_shadow *s = info->s;
1386
1387 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1388
1389 memcpy(info->bvec_data + info->bvec_offset,
1390 shared_data + offset, len);
1391
1392 info->bvec_offset += len;
1393 info->grant_idx++;
1394
1395 kunmap_atomic(shared_data);
1396 }
1397
blkif_rsp_to_req_status(int rsp)1398 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1399 {
1400 switch (rsp)
1401 {
1402 case BLKIF_RSP_OKAY:
1403 return REQ_DONE;
1404 case BLKIF_RSP_EOPNOTSUPP:
1405 return REQ_EOPNOTSUPP;
1406 case BLKIF_RSP_ERROR:
1407 default:
1408 return REQ_ERROR;
1409 }
1410 }
1411
1412 /*
1413 * Get the final status of the block request based on two ring response
1414 */
blkif_get_final_status(enum blk_req_status s1,enum blk_req_status s2)1415 static int blkif_get_final_status(enum blk_req_status s1,
1416 enum blk_req_status s2)
1417 {
1418 BUG_ON(s1 == REQ_WAITING);
1419 BUG_ON(s2 == REQ_WAITING);
1420
1421 if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1422 return BLKIF_RSP_ERROR;
1423 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1424 return BLKIF_RSP_EOPNOTSUPP;
1425 return BLKIF_RSP_OKAY;
1426 }
1427
blkif_completion(unsigned long * id,struct blkfront_ring_info * rinfo,struct blkif_response * bret)1428 static bool blkif_completion(unsigned long *id,
1429 struct blkfront_ring_info *rinfo,
1430 struct blkif_response *bret)
1431 {
1432 int i = 0;
1433 struct scatterlist *sg;
1434 int num_sg, num_grant;
1435 struct blkfront_info *info = rinfo->dev_info;
1436 struct blk_shadow *s = &rinfo->shadow[*id];
1437 struct copy_from_grant data = {
1438 .grant_idx = 0,
1439 };
1440
1441 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1442 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1443
1444 /* The I/O request may be split in two. */
1445 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1446 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1447
1448 /* Keep the status of the current response in shadow. */
1449 s->status = blkif_rsp_to_req_status(bret->status);
1450
1451 /* Wait the second response if not yet here. */
1452 if (s2->status == REQ_WAITING)
1453 return false;
1454
1455 bret->status = blkif_get_final_status(s->status,
1456 s2->status);
1457
1458 /*
1459 * All the grants is stored in the first shadow in order
1460 * to make the completion code simpler.
1461 */
1462 num_grant += s2->req.u.rw.nr_segments;
1463
1464 /*
1465 * The two responses may not come in order. Only the
1466 * first request will store the scatter-gather list.
1467 */
1468 if (s2->num_sg != 0) {
1469 /* Update "id" with the ID of the first response. */
1470 *id = s->associated_id;
1471 s = s2;
1472 }
1473
1474 /*
1475 * We don't need anymore the second request, so recycling
1476 * it now.
1477 */
1478 if (add_id_to_freelist(rinfo, s->associated_id))
1479 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1480 info->gd->disk_name, s->associated_id);
1481 }
1482
1483 data.s = s;
1484 num_sg = s->num_sg;
1485
1486 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1487 for_each_sg(s->sg, sg, num_sg, i) {
1488 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1489
1490 data.bvec_offset = sg->offset;
1491 data.bvec_data = kmap_atomic(sg_page(sg));
1492
1493 gnttab_foreach_grant_in_range(sg_page(sg),
1494 sg->offset,
1495 sg->length,
1496 blkif_copy_from_grant,
1497 &data);
1498
1499 kunmap_atomic(data.bvec_data);
1500 }
1501 }
1502 /* Add the persistent grant into the list of free grants */
1503 for (i = 0; i < num_grant; i++) {
1504 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1505 /*
1506 * If the grant is still mapped by the backend (the
1507 * backend has chosen to make this grant persistent)
1508 * we add it at the head of the list, so it will be
1509 * reused first.
1510 */
1511 if (!info->feature_persistent)
1512 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1513 s->grants_used[i]->gref);
1514 list_add(&s->grants_used[i]->node, &rinfo->grants);
1515 rinfo->persistent_gnts_c++;
1516 } else {
1517 /*
1518 * If the grant is not mapped by the backend we end the
1519 * foreign access and add it to the tail of the list,
1520 * so it will not be picked again unless we run out of
1521 * persistent grants.
1522 */
1523 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1524 s->grants_used[i]->gref = GRANT_INVALID_REF;
1525 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1526 }
1527 }
1528 if (s->req.operation == BLKIF_OP_INDIRECT) {
1529 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1530 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1531 if (!info->feature_persistent)
1532 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1533 s->indirect_grants[i]->gref);
1534 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1535 rinfo->persistent_gnts_c++;
1536 } else {
1537 struct page *indirect_page;
1538
1539 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1540 /*
1541 * Add the used indirect page back to the list of
1542 * available pages for indirect grefs.
1543 */
1544 if (!info->feature_persistent) {
1545 indirect_page = s->indirect_grants[i]->page;
1546 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1547 }
1548 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1549 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1550 }
1551 }
1552 }
1553
1554 return true;
1555 }
1556
blkif_interrupt(int irq,void * dev_id)1557 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1558 {
1559 struct request *req;
1560 struct blkif_response *bret;
1561 RING_IDX i, rp;
1562 unsigned long flags;
1563 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1564 struct blkfront_info *info = rinfo->dev_info;
1565
1566 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1567 return IRQ_HANDLED;
1568
1569 spin_lock_irqsave(&rinfo->ring_lock, flags);
1570 again:
1571 rp = rinfo->ring.sring->rsp_prod;
1572 rmb(); /* Ensure we see queued responses up to 'rp'. */
1573
1574 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1575 unsigned long id;
1576
1577 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1578 id = bret->id;
1579 /*
1580 * The backend has messed up and given us an id that we would
1581 * never have given to it (we stamp it up to BLK_RING_SIZE -
1582 * look in get_id_from_freelist.
1583 */
1584 if (id >= BLK_RING_SIZE(info)) {
1585 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1586 info->gd->disk_name, op_name(bret->operation), id);
1587 /* We can't safely get the 'struct request' as
1588 * the id is busted. */
1589 continue;
1590 }
1591 req = rinfo->shadow[id].request;
1592
1593 if (bret->operation != BLKIF_OP_DISCARD) {
1594 /*
1595 * We may need to wait for an extra response if the
1596 * I/O request is split in 2
1597 */
1598 if (!blkif_completion(&id, rinfo, bret))
1599 continue;
1600 }
1601
1602 if (add_id_to_freelist(rinfo, id)) {
1603 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1604 info->gd->disk_name, op_name(bret->operation), id);
1605 continue;
1606 }
1607
1608 if (bret->status == BLKIF_RSP_OKAY)
1609 blkif_req(req)->error = BLK_STS_OK;
1610 else
1611 blkif_req(req)->error = BLK_STS_IOERR;
1612
1613 switch (bret->operation) {
1614 case BLKIF_OP_DISCARD:
1615 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1616 struct request_queue *rq = info->rq;
1617 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1618 info->gd->disk_name, op_name(bret->operation));
1619 blkif_req(req)->error = BLK_STS_NOTSUPP;
1620 info->feature_discard = 0;
1621 info->feature_secdiscard = 0;
1622 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1623 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1624 }
1625 break;
1626 case BLKIF_OP_FLUSH_DISKCACHE:
1627 case BLKIF_OP_WRITE_BARRIER:
1628 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1629 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1630 info->gd->disk_name, op_name(bret->operation));
1631 blkif_req(req)->error = BLK_STS_NOTSUPP;
1632 }
1633 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1634 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1635 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1636 info->gd->disk_name, op_name(bret->operation));
1637 blkif_req(req)->error = BLK_STS_NOTSUPP;
1638 }
1639 if (unlikely(blkif_req(req)->error)) {
1640 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1641 blkif_req(req)->error = BLK_STS_OK;
1642 info->feature_fua = 0;
1643 info->feature_flush = 0;
1644 xlvbd_flush(info);
1645 }
1646 fallthrough;
1647 case BLKIF_OP_READ:
1648 case BLKIF_OP_WRITE:
1649 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1650 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1651 "request: %x\n", bret->status);
1652
1653 break;
1654 default:
1655 BUG();
1656 }
1657
1658 if (likely(!blk_should_fake_timeout(req->q)))
1659 blk_mq_complete_request(req);
1660 }
1661
1662 rinfo->ring.rsp_cons = i;
1663
1664 if (i != rinfo->ring.req_prod_pvt) {
1665 int more_to_do;
1666 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1667 if (more_to_do)
1668 goto again;
1669 } else
1670 rinfo->ring.sring->rsp_event = i + 1;
1671
1672 kick_pending_request_queues_locked(rinfo);
1673
1674 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1675
1676 return IRQ_HANDLED;
1677 }
1678
1679
setup_blkring(struct xenbus_device * dev,struct blkfront_ring_info * rinfo)1680 static int setup_blkring(struct xenbus_device *dev,
1681 struct blkfront_ring_info *rinfo)
1682 {
1683 struct blkif_sring *sring;
1684 int err, i;
1685 struct blkfront_info *info = rinfo->dev_info;
1686 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1687 grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1688
1689 for (i = 0; i < info->nr_ring_pages; i++)
1690 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1691
1692 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1693 get_order(ring_size));
1694 if (!sring) {
1695 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1696 return -ENOMEM;
1697 }
1698 SHARED_RING_INIT(sring);
1699 FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1700
1701 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1702 if (err < 0) {
1703 free_pages((unsigned long)sring, get_order(ring_size));
1704 rinfo->ring.sring = NULL;
1705 goto fail;
1706 }
1707 for (i = 0; i < info->nr_ring_pages; i++)
1708 rinfo->ring_ref[i] = gref[i];
1709
1710 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1711 if (err)
1712 goto fail;
1713
1714 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1715 "blkif", rinfo);
1716 if (err <= 0) {
1717 xenbus_dev_fatal(dev, err,
1718 "bind_evtchn_to_irqhandler failed");
1719 goto fail;
1720 }
1721 rinfo->irq = err;
1722
1723 return 0;
1724 fail:
1725 blkif_free(info, 0);
1726 return err;
1727 }
1728
1729 /*
1730 * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1731 * ring buffer may have multi pages depending on ->nr_ring_pages.
1732 */
write_per_ring_nodes(struct xenbus_transaction xbt,struct blkfront_ring_info * rinfo,const char * dir)1733 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1734 struct blkfront_ring_info *rinfo, const char *dir)
1735 {
1736 int err;
1737 unsigned int i;
1738 const char *message = NULL;
1739 struct blkfront_info *info = rinfo->dev_info;
1740
1741 if (info->nr_ring_pages == 1) {
1742 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1743 if (err) {
1744 message = "writing ring-ref";
1745 goto abort_transaction;
1746 }
1747 } else {
1748 for (i = 0; i < info->nr_ring_pages; i++) {
1749 char ring_ref_name[RINGREF_NAME_LEN];
1750
1751 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1752 err = xenbus_printf(xbt, dir, ring_ref_name,
1753 "%u", rinfo->ring_ref[i]);
1754 if (err) {
1755 message = "writing ring-ref";
1756 goto abort_transaction;
1757 }
1758 }
1759 }
1760
1761 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1762 if (err) {
1763 message = "writing event-channel";
1764 goto abort_transaction;
1765 }
1766
1767 return 0;
1768
1769 abort_transaction:
1770 xenbus_transaction_end(xbt, 1);
1771 if (message)
1772 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1773
1774 return err;
1775 }
1776
free_info(struct blkfront_info * info)1777 static void free_info(struct blkfront_info *info)
1778 {
1779 list_del(&info->info_list);
1780 kfree(info);
1781 }
1782
1783 /* Common code used when first setting up, and when resuming. */
talk_to_blkback(struct xenbus_device * dev,struct blkfront_info * info)1784 static int talk_to_blkback(struct xenbus_device *dev,
1785 struct blkfront_info *info)
1786 {
1787 const char *message = NULL;
1788 struct xenbus_transaction xbt;
1789 int err;
1790 unsigned int i, max_page_order;
1791 unsigned int ring_page_order;
1792 struct blkfront_ring_info *rinfo;
1793
1794 if (!info)
1795 return -ENODEV;
1796
1797 max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1798 "max-ring-page-order", 0);
1799 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1800 info->nr_ring_pages = 1 << ring_page_order;
1801
1802 err = negotiate_mq(info);
1803 if (err)
1804 goto destroy_blkring;
1805
1806 for_each_rinfo(info, rinfo, i) {
1807 /* Create shared ring, alloc event channel. */
1808 err = setup_blkring(dev, rinfo);
1809 if (err)
1810 goto destroy_blkring;
1811 }
1812
1813 again:
1814 err = xenbus_transaction_start(&xbt);
1815 if (err) {
1816 xenbus_dev_fatal(dev, err, "starting transaction");
1817 goto destroy_blkring;
1818 }
1819
1820 if (info->nr_ring_pages > 1) {
1821 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1822 ring_page_order);
1823 if (err) {
1824 message = "writing ring-page-order";
1825 goto abort_transaction;
1826 }
1827 }
1828
1829 /* We already got the number of queues/rings in _probe */
1830 if (info->nr_rings == 1) {
1831 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename);
1832 if (err)
1833 goto destroy_blkring;
1834 } else {
1835 char *path;
1836 size_t pathsize;
1837
1838 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1839 info->nr_rings);
1840 if (err) {
1841 message = "writing multi-queue-num-queues";
1842 goto abort_transaction;
1843 }
1844
1845 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1846 path = kmalloc(pathsize, GFP_KERNEL);
1847 if (!path) {
1848 err = -ENOMEM;
1849 message = "ENOMEM while writing ring references";
1850 goto abort_transaction;
1851 }
1852
1853 for_each_rinfo(info, rinfo, i) {
1854 memset(path, 0, pathsize);
1855 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1856 err = write_per_ring_nodes(xbt, rinfo, path);
1857 if (err) {
1858 kfree(path);
1859 goto destroy_blkring;
1860 }
1861 }
1862 kfree(path);
1863 }
1864 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1865 XEN_IO_PROTO_ABI_NATIVE);
1866 if (err) {
1867 message = "writing protocol";
1868 goto abort_transaction;
1869 }
1870 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
1871 info->feature_persistent);
1872 if (err)
1873 dev_warn(&dev->dev,
1874 "writing persistent grants feature to xenbus");
1875
1876 err = xenbus_transaction_end(xbt, 0);
1877 if (err) {
1878 if (err == -EAGAIN)
1879 goto again;
1880 xenbus_dev_fatal(dev, err, "completing transaction");
1881 goto destroy_blkring;
1882 }
1883
1884 for_each_rinfo(info, rinfo, i) {
1885 unsigned int j;
1886
1887 for (j = 0; j < BLK_RING_SIZE(info); j++)
1888 rinfo->shadow[j].req.u.rw.id = j + 1;
1889 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1890 }
1891 xenbus_switch_state(dev, XenbusStateInitialised);
1892
1893 return 0;
1894
1895 abort_transaction:
1896 xenbus_transaction_end(xbt, 1);
1897 if (message)
1898 xenbus_dev_fatal(dev, err, "%s", message);
1899 destroy_blkring:
1900 blkif_free(info, 0);
1901
1902 mutex_lock(&blkfront_mutex);
1903 free_info(info);
1904 mutex_unlock(&blkfront_mutex);
1905
1906 dev_set_drvdata(&dev->dev, NULL);
1907
1908 return err;
1909 }
1910
negotiate_mq(struct blkfront_info * info)1911 static int negotiate_mq(struct blkfront_info *info)
1912 {
1913 unsigned int backend_max_queues;
1914 unsigned int i;
1915 struct blkfront_ring_info *rinfo;
1916
1917 BUG_ON(info->nr_rings);
1918
1919 /* Check if backend supports multiple queues. */
1920 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1921 "multi-queue-max-queues", 1);
1922 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1923 /* We need at least one ring. */
1924 if (!info->nr_rings)
1925 info->nr_rings = 1;
1926
1927 info->rinfo_size = struct_size(info->rinfo, shadow,
1928 BLK_RING_SIZE(info));
1929 info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL);
1930 if (!info->rinfo) {
1931 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1932 info->nr_rings = 0;
1933 return -ENOMEM;
1934 }
1935
1936 for_each_rinfo(info, rinfo, i) {
1937 INIT_LIST_HEAD(&rinfo->indirect_pages);
1938 INIT_LIST_HEAD(&rinfo->grants);
1939 rinfo->dev_info = info;
1940 INIT_WORK(&rinfo->work, blkif_restart_queue);
1941 spin_lock_init(&rinfo->ring_lock);
1942 }
1943 return 0;
1944 }
1945
1946 /* Enable the persistent grants feature. */
1947 static bool feature_persistent = true;
1948 module_param(feature_persistent, bool, 0644);
1949 MODULE_PARM_DESC(feature_persistent,
1950 "Enables the persistent grants feature");
1951
1952 /*
1953 * Entry point to this code when a new device is created. Allocate the basic
1954 * structures and the ring buffer for communication with the backend, and
1955 * inform the backend of the appropriate details for those. Switch to
1956 * Initialised state.
1957 */
blkfront_probe(struct xenbus_device * dev,const struct xenbus_device_id * id)1958 static int blkfront_probe(struct xenbus_device *dev,
1959 const struct xenbus_device_id *id)
1960 {
1961 int err, vdevice;
1962 struct blkfront_info *info;
1963
1964 /* FIXME: Use dynamic device id if this is not set. */
1965 err = xenbus_scanf(XBT_NIL, dev->nodename,
1966 "virtual-device", "%i", &vdevice);
1967 if (err != 1) {
1968 /* go looking in the extended area instead */
1969 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1970 "%i", &vdevice);
1971 if (err != 1) {
1972 xenbus_dev_fatal(dev, err, "reading virtual-device");
1973 return err;
1974 }
1975 }
1976
1977 if (xen_hvm_domain()) {
1978 char *type;
1979 int len;
1980 /* no unplug has been done: do not hook devices != xen vbds */
1981 if (xen_has_pv_and_legacy_disk_devices()) {
1982 int major;
1983
1984 if (!VDEV_IS_EXTENDED(vdevice))
1985 major = BLKIF_MAJOR(vdevice);
1986 else
1987 major = XENVBD_MAJOR;
1988
1989 if (major != XENVBD_MAJOR) {
1990 printk(KERN_INFO
1991 "%s: HVM does not support vbd %d as xen block device\n",
1992 __func__, vdevice);
1993 return -ENODEV;
1994 }
1995 }
1996 /* do not create a PV cdrom device if we are an HVM guest */
1997 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1998 if (IS_ERR(type))
1999 return -ENODEV;
2000 if (strncmp(type, "cdrom", 5) == 0) {
2001 kfree(type);
2002 return -ENODEV;
2003 }
2004 kfree(type);
2005 }
2006 info = kzalloc(sizeof(*info), GFP_KERNEL);
2007 if (!info) {
2008 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
2009 return -ENOMEM;
2010 }
2011
2012 info->xbdev = dev;
2013
2014 mutex_init(&info->mutex);
2015 info->vdevice = vdevice;
2016 info->connected = BLKIF_STATE_DISCONNECTED;
2017
2018 info->feature_persistent = feature_persistent;
2019
2020 /* Front end dir is a number, which is used as the id. */
2021 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
2022 dev_set_drvdata(&dev->dev, info);
2023
2024 mutex_lock(&blkfront_mutex);
2025 list_add(&info->info_list, &info_list);
2026 mutex_unlock(&blkfront_mutex);
2027
2028 return 0;
2029 }
2030
blkif_recover(struct blkfront_info * info)2031 static int blkif_recover(struct blkfront_info *info)
2032 {
2033 unsigned int r_index;
2034 struct request *req, *n;
2035 int rc;
2036 struct bio *bio;
2037 unsigned int segs;
2038 struct blkfront_ring_info *rinfo;
2039
2040 blkfront_gather_backend_features(info);
2041 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2042 blkif_set_queue_limits(info);
2043 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2044 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2045
2046 for_each_rinfo(info, rinfo, r_index) {
2047 rc = blkfront_setup_indirect(rinfo);
2048 if (rc)
2049 return rc;
2050 }
2051 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2052
2053 /* Now safe for us to use the shared ring */
2054 info->connected = BLKIF_STATE_CONNECTED;
2055
2056 for_each_rinfo(info, rinfo, r_index) {
2057 /* Kick any other new requests queued since we resumed */
2058 kick_pending_request_queues(rinfo);
2059 }
2060
2061 list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2062 /* Requeue pending requests (flush or discard) */
2063 list_del_init(&req->queuelist);
2064 BUG_ON(req->nr_phys_segments > segs);
2065 blk_mq_requeue_request(req, false);
2066 }
2067 blk_mq_start_stopped_hw_queues(info->rq, true);
2068 blk_mq_kick_requeue_list(info->rq);
2069
2070 while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2071 /* Traverse the list of pending bios and re-queue them */
2072 submit_bio(bio);
2073 }
2074
2075 return 0;
2076 }
2077
2078 /*
2079 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2080 * driver restart. We tear down our blkif structure and recreate it, but
2081 * leave the device-layer structures intact so that this is transparent to the
2082 * rest of the kernel.
2083 */
blkfront_resume(struct xenbus_device * dev)2084 static int blkfront_resume(struct xenbus_device *dev)
2085 {
2086 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2087 int err = 0;
2088 unsigned int i, j;
2089 struct blkfront_ring_info *rinfo;
2090
2091 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2092
2093 bio_list_init(&info->bio_list);
2094 INIT_LIST_HEAD(&info->requests);
2095 for_each_rinfo(info, rinfo, i) {
2096 struct bio_list merge_bio;
2097 struct blk_shadow *shadow = rinfo->shadow;
2098
2099 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2100 /* Not in use? */
2101 if (!shadow[j].request)
2102 continue;
2103
2104 /*
2105 * Get the bios in the request so we can re-queue them.
2106 */
2107 if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2108 req_op(shadow[j].request) == REQ_OP_DISCARD ||
2109 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2110 shadow[j].request->cmd_flags & REQ_FUA) {
2111 /*
2112 * Flush operations don't contain bios, so
2113 * we need to requeue the whole request
2114 *
2115 * XXX: but this doesn't make any sense for a
2116 * write with the FUA flag set..
2117 */
2118 list_add(&shadow[j].request->queuelist, &info->requests);
2119 continue;
2120 }
2121 merge_bio.head = shadow[j].request->bio;
2122 merge_bio.tail = shadow[j].request->biotail;
2123 bio_list_merge(&info->bio_list, &merge_bio);
2124 shadow[j].request->bio = NULL;
2125 blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2126 }
2127 }
2128
2129 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2130
2131 err = talk_to_blkback(dev, info);
2132 if (!err)
2133 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2134
2135 /*
2136 * We have to wait for the backend to switch to
2137 * connected state, since we want to read which
2138 * features it supports.
2139 */
2140
2141 return err;
2142 }
2143
blkfront_closing(struct blkfront_info * info)2144 static void blkfront_closing(struct blkfront_info *info)
2145 {
2146 struct xenbus_device *xbdev = info->xbdev;
2147 struct block_device *bdev = NULL;
2148
2149 mutex_lock(&info->mutex);
2150
2151 if (xbdev->state == XenbusStateClosing) {
2152 mutex_unlock(&info->mutex);
2153 return;
2154 }
2155
2156 if (info->gd)
2157 bdev = bdgrab(info->gd->part0);
2158
2159 mutex_unlock(&info->mutex);
2160
2161 if (!bdev) {
2162 xenbus_frontend_closed(xbdev);
2163 return;
2164 }
2165
2166 mutex_lock(&bdev->bd_mutex);
2167
2168 if (bdev->bd_openers) {
2169 xenbus_dev_error(xbdev, -EBUSY,
2170 "Device in use; refusing to close");
2171 xenbus_switch_state(xbdev, XenbusStateClosing);
2172 } else {
2173 xlvbd_release_gendisk(info);
2174 xenbus_frontend_closed(xbdev);
2175 }
2176
2177 mutex_unlock(&bdev->bd_mutex);
2178 bdput(bdev);
2179 }
2180
blkfront_setup_discard(struct blkfront_info * info)2181 static void blkfront_setup_discard(struct blkfront_info *info)
2182 {
2183 info->feature_discard = 1;
2184 info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
2185 "discard-granularity",
2186 0);
2187 info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
2188 "discard-alignment", 0);
2189 info->feature_secdiscard =
2190 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2191 0);
2192 }
2193
blkfront_setup_indirect(struct blkfront_ring_info * rinfo)2194 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2195 {
2196 unsigned int psegs, grants, memflags;
2197 int err, i;
2198 struct blkfront_info *info = rinfo->dev_info;
2199
2200 memflags = memalloc_noio_save();
2201
2202 if (info->max_indirect_segments == 0) {
2203 if (!HAS_EXTRA_REQ)
2204 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2205 else {
2206 /*
2207 * When an extra req is required, the maximum
2208 * grants supported is related to the size of the
2209 * Linux block segment.
2210 */
2211 grants = GRANTS_PER_PSEG;
2212 }
2213 }
2214 else
2215 grants = info->max_indirect_segments;
2216 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2217
2218 err = fill_grant_buffer(rinfo,
2219 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2220 if (err)
2221 goto out_of_memory;
2222
2223 if (!info->feature_persistent && info->max_indirect_segments) {
2224 /*
2225 * We are using indirect descriptors but not persistent
2226 * grants, we need to allocate a set of pages that can be
2227 * used for mapping indirect grefs
2228 */
2229 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2230
2231 BUG_ON(!list_empty(&rinfo->indirect_pages));
2232 for (i = 0; i < num; i++) {
2233 struct page *indirect_page = alloc_page(GFP_KERNEL);
2234 if (!indirect_page)
2235 goto out_of_memory;
2236 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2237 }
2238 }
2239
2240 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2241 rinfo->shadow[i].grants_used =
2242 kvcalloc(grants,
2243 sizeof(rinfo->shadow[i].grants_used[0]),
2244 GFP_KERNEL);
2245 rinfo->shadow[i].sg = kvcalloc(psegs,
2246 sizeof(rinfo->shadow[i].sg[0]),
2247 GFP_KERNEL);
2248 if (info->max_indirect_segments)
2249 rinfo->shadow[i].indirect_grants =
2250 kvcalloc(INDIRECT_GREFS(grants),
2251 sizeof(rinfo->shadow[i].indirect_grants[0]),
2252 GFP_KERNEL);
2253 if ((rinfo->shadow[i].grants_used == NULL) ||
2254 (rinfo->shadow[i].sg == NULL) ||
2255 (info->max_indirect_segments &&
2256 (rinfo->shadow[i].indirect_grants == NULL)))
2257 goto out_of_memory;
2258 sg_init_table(rinfo->shadow[i].sg, psegs);
2259 }
2260
2261 memalloc_noio_restore(memflags);
2262
2263 return 0;
2264
2265 out_of_memory:
2266 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2267 kvfree(rinfo->shadow[i].grants_used);
2268 rinfo->shadow[i].grants_used = NULL;
2269 kvfree(rinfo->shadow[i].sg);
2270 rinfo->shadow[i].sg = NULL;
2271 kvfree(rinfo->shadow[i].indirect_grants);
2272 rinfo->shadow[i].indirect_grants = NULL;
2273 }
2274 if (!list_empty(&rinfo->indirect_pages)) {
2275 struct page *indirect_page, *n;
2276 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2277 list_del(&indirect_page->lru);
2278 __free_page(indirect_page);
2279 }
2280 }
2281
2282 memalloc_noio_restore(memflags);
2283
2284 return -ENOMEM;
2285 }
2286
2287 /*
2288 * Gather all backend feature-*
2289 */
blkfront_gather_backend_features(struct blkfront_info * info)2290 static void blkfront_gather_backend_features(struct blkfront_info *info)
2291 {
2292 unsigned int indirect_segments;
2293
2294 info->feature_flush = 0;
2295 info->feature_fua = 0;
2296
2297 /*
2298 * If there's no "feature-barrier" defined, then it means
2299 * we're dealing with a very old backend which writes
2300 * synchronously; nothing to do.
2301 *
2302 * If there are barriers, then we use flush.
2303 */
2304 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2305 info->feature_flush = 1;
2306 info->feature_fua = 1;
2307 }
2308
2309 /*
2310 * And if there is "feature-flush-cache" use that above
2311 * barriers.
2312 */
2313 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2314 0)) {
2315 info->feature_flush = 1;
2316 info->feature_fua = 0;
2317 }
2318
2319 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2320 blkfront_setup_discard(info);
2321
2322 if (info->feature_persistent)
2323 info->feature_persistent =
2324 !!xenbus_read_unsigned(info->xbdev->otherend,
2325 "feature-persistent", 0);
2326
2327 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2328 "feature-max-indirect-segments", 0);
2329 if (indirect_segments > xen_blkif_max_segments)
2330 indirect_segments = xen_blkif_max_segments;
2331 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2332 indirect_segments = 0;
2333 info->max_indirect_segments = indirect_segments;
2334
2335 if (info->feature_persistent) {
2336 mutex_lock(&blkfront_mutex);
2337 schedule_delayed_work(&blkfront_work, HZ * 10);
2338 mutex_unlock(&blkfront_mutex);
2339 }
2340 }
2341
2342 /*
2343 * Invoked when the backend is finally 'ready' (and has told produced
2344 * the details about the physical device - #sectors, size, etc).
2345 */
blkfront_connect(struct blkfront_info * info)2346 static void blkfront_connect(struct blkfront_info *info)
2347 {
2348 unsigned long long sectors;
2349 unsigned long sector_size;
2350 unsigned int physical_sector_size;
2351 unsigned int binfo;
2352 int err, i;
2353 struct blkfront_ring_info *rinfo;
2354
2355 switch (info->connected) {
2356 case BLKIF_STATE_CONNECTED:
2357 /*
2358 * Potentially, the back-end may be signalling
2359 * a capacity change; update the capacity.
2360 */
2361 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2362 "sectors", "%Lu", §ors);
2363 if (XENBUS_EXIST_ERR(err))
2364 return;
2365 printk(KERN_INFO "Setting capacity to %Lu\n",
2366 sectors);
2367 set_capacity_and_notify(info->gd, sectors);
2368
2369 return;
2370 case BLKIF_STATE_SUSPENDED:
2371 /*
2372 * If we are recovering from suspension, we need to wait
2373 * for the backend to announce it's features before
2374 * reconnecting, at least we need to know if the backend
2375 * supports indirect descriptors, and how many.
2376 */
2377 blkif_recover(info);
2378 return;
2379
2380 default:
2381 break;
2382 }
2383
2384 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2385 __func__, info->xbdev->otherend);
2386
2387 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2388 "sectors", "%llu", §ors,
2389 "info", "%u", &binfo,
2390 "sector-size", "%lu", §or_size,
2391 NULL);
2392 if (err) {
2393 xenbus_dev_fatal(info->xbdev, err,
2394 "reading backend fields at %s",
2395 info->xbdev->otherend);
2396 return;
2397 }
2398
2399 /*
2400 * physical-sector-size is a newer field, so old backends may not
2401 * provide this. Assume physical sector size to be the same as
2402 * sector_size in that case.
2403 */
2404 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2405 "physical-sector-size",
2406 sector_size);
2407 blkfront_gather_backend_features(info);
2408 for_each_rinfo(info, rinfo, i) {
2409 err = blkfront_setup_indirect(rinfo);
2410 if (err) {
2411 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2412 info->xbdev->otherend);
2413 blkif_free(info, 0);
2414 break;
2415 }
2416 }
2417
2418 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2419 physical_sector_size);
2420 if (err) {
2421 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2422 info->xbdev->otherend);
2423 goto fail;
2424 }
2425
2426 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2427
2428 /* Kick pending requests. */
2429 info->connected = BLKIF_STATE_CONNECTED;
2430 for_each_rinfo(info, rinfo, i)
2431 kick_pending_request_queues(rinfo);
2432
2433 device_add_disk(&info->xbdev->dev, info->gd, NULL);
2434
2435 info->is_ready = 1;
2436 return;
2437
2438 fail:
2439 blkif_free(info, 0);
2440 return;
2441 }
2442
2443 /*
2444 * Callback received when the backend's state changes.
2445 */
blkback_changed(struct xenbus_device * dev,enum xenbus_state backend_state)2446 static void blkback_changed(struct xenbus_device *dev,
2447 enum xenbus_state backend_state)
2448 {
2449 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2450
2451 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2452
2453 switch (backend_state) {
2454 case XenbusStateInitWait:
2455 if (dev->state != XenbusStateInitialising)
2456 break;
2457 if (talk_to_blkback(dev, info))
2458 break;
2459 break;
2460 case XenbusStateInitialising:
2461 case XenbusStateInitialised:
2462 case XenbusStateReconfiguring:
2463 case XenbusStateReconfigured:
2464 case XenbusStateUnknown:
2465 break;
2466
2467 case XenbusStateConnected:
2468 /*
2469 * talk_to_blkback sets state to XenbusStateInitialised
2470 * and blkfront_connect sets it to XenbusStateConnected
2471 * (if connection went OK).
2472 *
2473 * If the backend (or toolstack) decides to poke at backend
2474 * state (and re-trigger the watch by setting the state repeatedly
2475 * to XenbusStateConnected (4)) we need to deal with this.
2476 * This is allowed as this is used to communicate to the guest
2477 * that the size of disk has changed!
2478 */
2479 if ((dev->state != XenbusStateInitialised) &&
2480 (dev->state != XenbusStateConnected)) {
2481 if (talk_to_blkback(dev, info))
2482 break;
2483 }
2484
2485 blkfront_connect(info);
2486 break;
2487
2488 case XenbusStateClosed:
2489 if (dev->state == XenbusStateClosed)
2490 break;
2491 fallthrough;
2492 case XenbusStateClosing:
2493 if (info)
2494 blkfront_closing(info);
2495 break;
2496 }
2497 }
2498
blkfront_remove(struct xenbus_device * xbdev)2499 static int blkfront_remove(struct xenbus_device *xbdev)
2500 {
2501 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2502 struct block_device *bdev = NULL;
2503 struct gendisk *disk;
2504
2505 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2506
2507 if (!info)
2508 return 0;
2509
2510 blkif_free(info, 0);
2511
2512 mutex_lock(&info->mutex);
2513
2514 disk = info->gd;
2515 if (disk)
2516 bdev = bdgrab(disk->part0);
2517
2518 info->xbdev = NULL;
2519 mutex_unlock(&info->mutex);
2520
2521 if (!bdev) {
2522 mutex_lock(&blkfront_mutex);
2523 free_info(info);
2524 mutex_unlock(&blkfront_mutex);
2525 return 0;
2526 }
2527
2528 /*
2529 * The xbdev was removed before we reached the Closed
2530 * state. See if it's safe to remove the disk. If the bdev
2531 * isn't closed yet, we let release take care of it.
2532 */
2533
2534 mutex_lock(&bdev->bd_mutex);
2535 info = disk->private_data;
2536
2537 dev_warn(disk_to_dev(disk),
2538 "%s was hot-unplugged, %d stale handles\n",
2539 xbdev->nodename, bdev->bd_openers);
2540
2541 if (info && !bdev->bd_openers) {
2542 xlvbd_release_gendisk(info);
2543 disk->private_data = NULL;
2544 mutex_lock(&blkfront_mutex);
2545 free_info(info);
2546 mutex_unlock(&blkfront_mutex);
2547 }
2548
2549 mutex_unlock(&bdev->bd_mutex);
2550 bdput(bdev);
2551
2552 return 0;
2553 }
2554
blkfront_is_ready(struct xenbus_device * dev)2555 static int blkfront_is_ready(struct xenbus_device *dev)
2556 {
2557 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2558
2559 return info->is_ready && info->xbdev;
2560 }
2561
blkif_open(struct block_device * bdev,fmode_t mode)2562 static int blkif_open(struct block_device *bdev, fmode_t mode)
2563 {
2564 struct gendisk *disk = bdev->bd_disk;
2565 struct blkfront_info *info;
2566 int err = 0;
2567
2568 mutex_lock(&blkfront_mutex);
2569
2570 info = disk->private_data;
2571 if (!info) {
2572 /* xbdev gone */
2573 err = -ERESTARTSYS;
2574 goto out;
2575 }
2576
2577 mutex_lock(&info->mutex);
2578
2579 if (!info->gd)
2580 /* xbdev is closed */
2581 err = -ERESTARTSYS;
2582
2583 mutex_unlock(&info->mutex);
2584
2585 out:
2586 mutex_unlock(&blkfront_mutex);
2587 return err;
2588 }
2589
blkif_release(struct gendisk * disk,fmode_t mode)2590 static void blkif_release(struct gendisk *disk, fmode_t mode)
2591 {
2592 struct blkfront_info *info = disk->private_data;
2593 struct xenbus_device *xbdev;
2594
2595 mutex_lock(&blkfront_mutex);
2596 if (disk->part0->bd_openers)
2597 goto out_mutex;
2598
2599 /*
2600 * Check if we have been instructed to close. We will have
2601 * deferred this request, because the bdev was still open.
2602 */
2603
2604 mutex_lock(&info->mutex);
2605 xbdev = info->xbdev;
2606
2607 if (xbdev && xbdev->state == XenbusStateClosing) {
2608 /* pending switch to state closed */
2609 dev_info(disk_to_dev(disk), "releasing disk\n");
2610 xlvbd_release_gendisk(info);
2611 xenbus_frontend_closed(info->xbdev);
2612 }
2613
2614 mutex_unlock(&info->mutex);
2615
2616 if (!xbdev) {
2617 /* sudden device removal */
2618 dev_info(disk_to_dev(disk), "releasing disk\n");
2619 xlvbd_release_gendisk(info);
2620 disk->private_data = NULL;
2621 free_info(info);
2622 }
2623
2624 out_mutex:
2625 mutex_unlock(&blkfront_mutex);
2626 }
2627
2628 static const struct block_device_operations xlvbd_block_fops =
2629 {
2630 .owner = THIS_MODULE,
2631 .open = blkif_open,
2632 .release = blkif_release,
2633 .getgeo = blkif_getgeo,
2634 .ioctl = blkif_ioctl,
2635 .compat_ioctl = blkdev_compat_ptr_ioctl,
2636 };
2637
2638
2639 static const struct xenbus_device_id blkfront_ids[] = {
2640 { "vbd" },
2641 { "" }
2642 };
2643
2644 static struct xenbus_driver blkfront_driver = {
2645 .ids = blkfront_ids,
2646 .probe = blkfront_probe,
2647 .remove = blkfront_remove,
2648 .resume = blkfront_resume,
2649 .otherend_changed = blkback_changed,
2650 .is_ready = blkfront_is_ready,
2651 };
2652
purge_persistent_grants(struct blkfront_info * info)2653 static void purge_persistent_grants(struct blkfront_info *info)
2654 {
2655 unsigned int i;
2656 unsigned long flags;
2657 struct blkfront_ring_info *rinfo;
2658
2659 for_each_rinfo(info, rinfo, i) {
2660 struct grant *gnt_list_entry, *tmp;
2661
2662 spin_lock_irqsave(&rinfo->ring_lock, flags);
2663
2664 if (rinfo->persistent_gnts_c == 0) {
2665 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2666 continue;
2667 }
2668
2669 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2670 node) {
2671 if (gnt_list_entry->gref == GRANT_INVALID_REF ||
2672 gnttab_query_foreign_access(gnt_list_entry->gref))
2673 continue;
2674
2675 list_del(&gnt_list_entry->node);
2676 gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
2677 rinfo->persistent_gnts_c--;
2678 gnt_list_entry->gref = GRANT_INVALID_REF;
2679 list_add_tail(&gnt_list_entry->node, &rinfo->grants);
2680 }
2681
2682 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2683 }
2684 }
2685
blkfront_delay_work(struct work_struct * work)2686 static void blkfront_delay_work(struct work_struct *work)
2687 {
2688 struct blkfront_info *info;
2689 bool need_schedule_work = false;
2690
2691 mutex_lock(&blkfront_mutex);
2692
2693 list_for_each_entry(info, &info_list, info_list) {
2694 if (info->feature_persistent) {
2695 need_schedule_work = true;
2696 mutex_lock(&info->mutex);
2697 purge_persistent_grants(info);
2698 mutex_unlock(&info->mutex);
2699 }
2700 }
2701
2702 if (need_schedule_work)
2703 schedule_delayed_work(&blkfront_work, HZ * 10);
2704
2705 mutex_unlock(&blkfront_mutex);
2706 }
2707
xlblk_init(void)2708 static int __init xlblk_init(void)
2709 {
2710 int ret;
2711 int nr_cpus = num_online_cpus();
2712
2713 if (!xen_domain())
2714 return -ENODEV;
2715
2716 if (!xen_has_pv_disk_devices())
2717 return -ENODEV;
2718
2719 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2720 pr_warn("xen_blk: can't get major %d with name %s\n",
2721 XENVBD_MAJOR, DEV_NAME);
2722 return -ENODEV;
2723 }
2724
2725 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2726 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2727
2728 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2729 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2730 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2731 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2732 }
2733
2734 if (xen_blkif_max_queues > nr_cpus) {
2735 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2736 xen_blkif_max_queues, nr_cpus);
2737 xen_blkif_max_queues = nr_cpus;
2738 }
2739
2740 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2741
2742 ret = xenbus_register_frontend(&blkfront_driver);
2743 if (ret) {
2744 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2745 return ret;
2746 }
2747
2748 return 0;
2749 }
2750 module_init(xlblk_init);
2751
2752
xlblk_exit(void)2753 static void __exit xlblk_exit(void)
2754 {
2755 cancel_delayed_work_sync(&blkfront_work);
2756
2757 xenbus_unregister_driver(&blkfront_driver);
2758 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2759 kfree(minors);
2760 }
2761 module_exit(xlblk_exit);
2762
2763 MODULE_DESCRIPTION("Xen virtual block device frontend");
2764 MODULE_LICENSE("GPL");
2765 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2766 MODULE_ALIAS("xen:vbd");
2767 MODULE_ALIAS("xenblk");
2768