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1/*
2 * blkfront.c
3 *
4 * XenLinux virtual block device driver.
5 *
6 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
7 * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
8 * Copyright (c) 2004, Christian Limpach
9 * Copyright (c) 2004, Andrew Warfield
10 * Copyright (c) 2005, Christopher Clark
11 * Copyright (c) 2005, XenSource Ltd
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License version 2
15 * as published by the Free Software Foundation; or, when distributed
16 * separately from the Linux kernel or incorporated into other
17 * software packages, subject to the following license:
18 *
19 * Permission is hereby granted, free of charge, to any person obtaining a copy
20 * of this source file (the "Software"), to deal in the Software without
21 * restriction, including without limitation the rights to use, copy, modify,
22 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
23 * and to permit persons to whom the Software is furnished to do so, subject to
24 * the following conditions:
25 *
26 * The above copyright notice and this permission notice shall be included in
27 * all copies or substantial portions of the Software.
28 *
29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
35 * IN THE SOFTWARE.
36 */
37
38#include <linux/interrupt.h>
39#include <linux/blkdev.h>
40#include <linux/hdreg.h>
41#include <linux/cdrom.h>
42#include <linux/module.h>
43#include <linux/slab.h>
44#include <linux/mutex.h>
45#include <linux/scatterlist.h>
46
47#include <xen/xen.h>
48#include <xen/xenbus.h>
49#include <xen/grant_table.h>
50#include <xen/events.h>
51#include <xen/page.h>
52#include <xen/platform_pci.h>
53
54#include <xen/interface/grant_table.h>
55#include <xen/interface/io/blkif.h>
56#include <xen/interface/io/protocols.h>
57
58#include <asm/xen/hypervisor.h>
59
60enum blkif_state {
61 BLKIF_STATE_DISCONNECTED,
62 BLKIF_STATE_CONNECTED,
63 BLKIF_STATE_SUSPENDED,
64};
65
66struct blk_shadow {
67 struct blkif_request req;
68 struct request *request;
69 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
70};
71
72static DEFINE_MUTEX(blkfront_mutex);
73static const struct block_device_operations xlvbd_block_fops;
74
75#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
76
77/*
78 * We have one of these per vbd, whether ide, scsi or 'other'. They
79 * hang in private_data off the gendisk structure. We may end up
80 * putting all kinds of interesting stuff here :-)
81 */
82struct blkfront_info
83{
84 struct mutex mutex;
85 struct xenbus_device *xbdev;
86 struct gendisk *gd;
87 int vdevice;
88 blkif_vdev_t handle;
89 enum blkif_state connected;
90 int ring_ref;
91 struct blkif_front_ring ring;
92 struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
93 unsigned int evtchn, irq;
94 struct request_queue *rq;
95 struct work_struct work;
96 struct gnttab_free_callback callback;
97 struct blk_shadow shadow[BLK_RING_SIZE];
98 unsigned long shadow_free;
99 unsigned int feature_flush;
100 unsigned int flush_op;
101 int is_ready;
102};
103
104static DEFINE_SPINLOCK(blkif_io_lock);
105
106static unsigned int nr_minors;
107static unsigned long *minors;
108static DEFINE_SPINLOCK(minor_lock);
109
110#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
111 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
112#define GRANT_INVALID_REF 0
113
114#define PARTS_PER_DISK 16
115#define PARTS_PER_EXT_DISK 256
116
117#define BLKIF_MAJOR(dev) ((dev)>>8)
118#define BLKIF_MINOR(dev) ((dev) & 0xff)
119
120#define EXT_SHIFT 28
121#define EXTENDED (1<<EXT_SHIFT)
122#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
123#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
124#define EMULATED_HD_DISK_MINOR_OFFSET (0)
125#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
126#define EMULATED_SD_DISK_MINOR_OFFSET (0)
127#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
128
129#define DEV_NAME "xvd" /* name in /dev */
130
131static int get_id_from_freelist(struct blkfront_info *info)
132{
133 unsigned long free = info->shadow_free;
134 BUG_ON(free >= BLK_RING_SIZE);
135 info->shadow_free = info->shadow[free].req.id;
136 info->shadow[free].req.id = 0x0fffffee; /* debug */
137 return free;
138}
139
140static void add_id_to_freelist(struct blkfront_info *info,
141 unsigned long id)
142{
143 info->shadow[id].req.id = info->shadow_free;
144 info->shadow[id].request = NULL;
145 info->shadow_free = id;
146}
147
148static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
149{
150 unsigned int end = minor + nr;
151 int rc;
152
153 if (end > nr_minors) {
154 unsigned long *bitmap, *old;
155
156 bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
157 GFP_KERNEL);
158 if (bitmap == NULL)
159 return -ENOMEM;
160
161 spin_lock(&minor_lock);
162 if (end > nr_minors) {
163 old = minors;
164 memcpy(bitmap, minors,
165 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
166 minors = bitmap;
167 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
168 } else
169 old = bitmap;
170 spin_unlock(&minor_lock);
171 kfree(old);
172 }
173
174 spin_lock(&minor_lock);
175 if (find_next_bit(minors, end, minor) >= end) {
176 for (; minor < end; ++minor)
177 __set_bit(minor, minors);
178 rc = 0;
179 } else
180 rc = -EBUSY;
181 spin_unlock(&minor_lock);
182
183 return rc;
184}
185
186static void xlbd_release_minors(unsigned int minor, unsigned int nr)
187{
188 unsigned int end = minor + nr;
189
190 BUG_ON(end > nr_minors);
191 spin_lock(&minor_lock);
192 for (; minor < end; ++minor)
193 __clear_bit(minor, minors);
194 spin_unlock(&minor_lock);
195}
196
197static void blkif_restart_queue_callback(void *arg)
198{
199 struct blkfront_info *info = (struct blkfront_info *)arg;
200 schedule_work(&info->work);
201}
202
203static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
204{
205 /* We don't have real geometry info, but let's at least return
206 values consistent with the size of the device */
207 sector_t nsect = get_capacity(bd->bd_disk);
208 sector_t cylinders = nsect;
209
210 hg->heads = 0xff;
211 hg->sectors = 0x3f;
212 sector_div(cylinders, hg->heads * hg->sectors);
213 hg->cylinders = cylinders;
214 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
215 hg->cylinders = 0xffff;
216 return 0;
217}
218
219static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
220 unsigned command, unsigned long argument)
221{
222 struct blkfront_info *info = bdev->bd_disk->private_data;
223 int i;
224
225 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
226 command, (long)argument);
227
228 switch (command) {
229 case CDROMMULTISESSION:
230 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
231 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
232 if (put_user(0, (char __user *)(argument + i)))
233 return -EFAULT;
234 return 0;
235
236 case CDROM_GET_CAPABILITY: {
237 struct gendisk *gd = info->gd;
238 if (gd->flags & GENHD_FL_CD)
239 return 0;
240 return -EINVAL;
241 }
242
243 default:
244 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
245 command);*/
246 return -EINVAL; /* same return as native Linux */
247 }
248
249 return 0;
250}
251
252/*
253 * Generate a Xen blkfront IO request from a blk layer request. Reads
254 * and writes are handled as expected.
255 *
256 * @req: a request struct
257 */
258static int blkif_queue_request(struct request *req)
259{
260 struct blkfront_info *info = req->rq_disk->private_data;
261 unsigned long buffer_mfn;
262 struct blkif_request *ring_req;
263 unsigned long id;
264 unsigned int fsect, lsect;
265 int i, ref;
266 grant_ref_t gref_head;
267 struct scatterlist *sg;
268
269 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
270 return 1;
271
272 if (gnttab_alloc_grant_references(
273 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
274 gnttab_request_free_callback(
275 &info->callback,
276 blkif_restart_queue_callback,
277 info,
278 BLKIF_MAX_SEGMENTS_PER_REQUEST);
279 return 1;
280 }
281
282 /* Fill out a communications ring structure. */
283 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
284 id = get_id_from_freelist(info);
285 info->shadow[id].request = req;
286
287 ring_req->id = id;
288 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
289 ring_req->handle = info->handle;
290
291 ring_req->operation = rq_data_dir(req) ?
292 BLKIF_OP_WRITE : BLKIF_OP_READ;
293
294 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
295 /*
296 * Ideally we can do an unordered flush-to-disk. In case the
297 * backend onlysupports barriers, use that. A barrier request
298 * a superset of FUA, so we can implement it the same
299 * way. (It's also a FLUSH+FUA, since it is
300 * guaranteed ordered WRT previous writes.)
301 */
302 ring_req->operation = info->flush_op;
303 }
304
305 ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
306 BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
307
308 for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
309 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
310 fsect = sg->offset >> 9;
311 lsect = fsect + (sg->length >> 9) - 1;
312 /* install a grant reference. */
313 ref = gnttab_claim_grant_reference(&gref_head);
314 BUG_ON(ref == -ENOSPC);
315
316 gnttab_grant_foreign_access_ref(
317 ref,
318 info->xbdev->otherend_id,
319 buffer_mfn,
320 rq_data_dir(req) );
321
322 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
323 ring_req->u.rw.seg[i] =
324 (struct blkif_request_segment) {
325 .gref = ref,
326 .first_sect = fsect,
327 .last_sect = lsect };
328 }
329
330 info->ring.req_prod_pvt++;
331
332 /* Keep a private copy so we can reissue requests when recovering. */
333 info->shadow[id].req = *ring_req;
334
335 gnttab_free_grant_references(gref_head);
336
337 return 0;
338}
339
340
341static inline void flush_requests(struct blkfront_info *info)
342{
343 int notify;
344
345 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
346
347 if (notify)
348 notify_remote_via_irq(info->irq);
349}
350
351/*
352 * do_blkif_request
353 * read a block; request is in a request queue
354 */
355static void do_blkif_request(struct request_queue *rq)
356{
357 struct blkfront_info *info = NULL;
358 struct request *req;
359 int queued;
360
361 pr_debug("Entered do_blkif_request\n");
362
363 queued = 0;
364
365 while ((req = blk_peek_request(rq)) != NULL) {
366 info = req->rq_disk->private_data;
367
368 if (RING_FULL(&info->ring))
369 goto wait;
370
371 blk_start_request(req);
372
373 if (req->cmd_type != REQ_TYPE_FS) {
374 __blk_end_request_all(req, -EIO);
375 continue;
376 }
377
378 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
379 "(%u/%u) buffer:%p [%s]\n",
380 req, req->cmd, (unsigned long)blk_rq_pos(req),
381 blk_rq_cur_sectors(req), blk_rq_sectors(req),
382 req->buffer, rq_data_dir(req) ? "write" : "read");
383
384 if (blkif_queue_request(req)) {
385 blk_requeue_request(rq, req);
386wait:
387 /* Avoid pointless unplugs. */
388 blk_stop_queue(rq);
389 break;
390 }
391
392 queued++;
393 }
394
395 if (queued != 0)
396 flush_requests(info);
397}
398
399static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
400{
401 struct request_queue *rq;
402
403 rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
404 if (rq == NULL)
405 return -1;
406
407 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
408
409 /* Hard sector size and max sectors impersonate the equiv. hardware. */
410 blk_queue_logical_block_size(rq, sector_size);
411 blk_queue_max_hw_sectors(rq, 512);
412
413 /* Each segment in a request is up to an aligned page in size. */
414 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
415 blk_queue_max_segment_size(rq, PAGE_SIZE);
416
417 /* Ensure a merged request will fit in a single I/O ring slot. */
418 blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
419
420 /* Make sure buffer addresses are sector-aligned. */
421 blk_queue_dma_alignment(rq, 511);
422
423 /* Make sure we don't use bounce buffers. */
424 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
425
426 gd->queue = rq;
427
428 return 0;
429}
430
431
432static void xlvbd_flush(struct blkfront_info *info)
433{
434 blk_queue_flush(info->rq, info->feature_flush);
435 printk(KERN_INFO "blkfront: %s: %s: %s\n",
436 info->gd->disk_name,
437 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
438 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
439 "flush diskcache" : "barrier or flush"),
440 info->feature_flush ? "enabled" : "disabled");
441}
442
443static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
444{
445 int major;
446 major = BLKIF_MAJOR(vdevice);
447 *minor = BLKIF_MINOR(vdevice);
448 switch (major) {
449 case XEN_IDE0_MAJOR:
450 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
451 *minor = ((*minor / 64) * PARTS_PER_DISK) +
452 EMULATED_HD_DISK_MINOR_OFFSET;
453 break;
454 case XEN_IDE1_MAJOR:
455 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
456 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
457 EMULATED_HD_DISK_MINOR_OFFSET;
458 break;
459 case XEN_SCSI_DISK0_MAJOR:
460 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
461 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
462 break;
463 case XEN_SCSI_DISK1_MAJOR:
464 case XEN_SCSI_DISK2_MAJOR:
465 case XEN_SCSI_DISK3_MAJOR:
466 case XEN_SCSI_DISK4_MAJOR:
467 case XEN_SCSI_DISK5_MAJOR:
468 case XEN_SCSI_DISK6_MAJOR:
469 case XEN_SCSI_DISK7_MAJOR:
470 *offset = (*minor / PARTS_PER_DISK) +
471 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
472 EMULATED_SD_DISK_NAME_OFFSET;
473 *minor = *minor +
474 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
475 EMULATED_SD_DISK_MINOR_OFFSET;
476 break;
477 case XEN_SCSI_DISK8_MAJOR:
478 case XEN_SCSI_DISK9_MAJOR:
479 case XEN_SCSI_DISK10_MAJOR:
480 case XEN_SCSI_DISK11_MAJOR:
481 case XEN_SCSI_DISK12_MAJOR:
482 case XEN_SCSI_DISK13_MAJOR:
483 case XEN_SCSI_DISK14_MAJOR:
484 case XEN_SCSI_DISK15_MAJOR:
485 *offset = (*minor / PARTS_PER_DISK) +
486 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
487 EMULATED_SD_DISK_NAME_OFFSET;
488 *minor = *minor +
489 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
490 EMULATED_SD_DISK_MINOR_OFFSET;
491 break;
492 case XENVBD_MAJOR:
493 *offset = *minor / PARTS_PER_DISK;
494 break;
495 default:
496 printk(KERN_WARNING "blkfront: your disk configuration is "
497 "incorrect, please use an xvd device instead\n");
498 return -ENODEV;
499 }
500 return 0;
501}
502
503static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
504 struct blkfront_info *info,
505 u16 vdisk_info, u16 sector_size)
506{
507 struct gendisk *gd;
508 int nr_minors = 1;
509 int err;
510 unsigned int offset;
511 int minor;
512 int nr_parts;
513
514 BUG_ON(info->gd != NULL);
515 BUG_ON(info->rq != NULL);
516
517 if ((info->vdevice>>EXT_SHIFT) > 1) {
518 /* this is above the extended range; something is wrong */
519 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
520 return -ENODEV;
521 }
522
523 if (!VDEV_IS_EXTENDED(info->vdevice)) {
524 err = xen_translate_vdev(info->vdevice, &minor, &offset);
525 if (err)
526 return err;
527 nr_parts = PARTS_PER_DISK;
528 } else {
529 minor = BLKIF_MINOR_EXT(info->vdevice);
530 nr_parts = PARTS_PER_EXT_DISK;
531 offset = minor / nr_parts;
532 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
533 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
534 "emulated IDE disks,\n\t choose an xvd device name"
535 "from xvde on\n", info->vdevice);
536 }
537 err = -ENODEV;
538
539 if ((minor % nr_parts) == 0)
540 nr_minors = nr_parts;
541
542 err = xlbd_reserve_minors(minor, nr_minors);
543 if (err)
544 goto out;
545 err = -ENODEV;
546
547 gd = alloc_disk(nr_minors);
548 if (gd == NULL)
549 goto release;
550
551 if (nr_minors > 1) {
552 if (offset < 26)
553 sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
554 else
555 sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
556 'a' + ((offset / 26)-1), 'a' + (offset % 26));
557 } else {
558 if (offset < 26)
559 sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
560 'a' + offset,
561 minor & (nr_parts - 1));
562 else
563 sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
564 'a' + ((offset / 26) - 1),
565 'a' + (offset % 26),
566 minor & (nr_parts - 1));
567 }
568
569 gd->major = XENVBD_MAJOR;
570 gd->first_minor = minor;
571 gd->fops = &xlvbd_block_fops;
572 gd->private_data = info;
573 gd->driverfs_dev = &(info->xbdev->dev);
574 set_capacity(gd, capacity);
575
576 if (xlvbd_init_blk_queue(gd, sector_size)) {
577 del_gendisk(gd);
578 goto release;
579 }
580
581 info->rq = gd->queue;
582 info->gd = gd;
583
584 xlvbd_flush(info);
585
586 if (vdisk_info & VDISK_READONLY)
587 set_disk_ro(gd, 1);
588
589 if (vdisk_info & VDISK_REMOVABLE)
590 gd->flags |= GENHD_FL_REMOVABLE;
591
592 if (vdisk_info & VDISK_CDROM)
593 gd->flags |= GENHD_FL_CD;
594
595 return 0;
596
597 release:
598 xlbd_release_minors(minor, nr_minors);
599 out:
600 return err;
601}
602
603static void xlvbd_release_gendisk(struct blkfront_info *info)
604{
605 unsigned int minor, nr_minors;
606 unsigned long flags;
607
608 if (info->rq == NULL)
609 return;
610
611 spin_lock_irqsave(&blkif_io_lock, flags);
612
613 /* No more blkif_request(). */
614 blk_stop_queue(info->rq);
615
616 /* No more gnttab callback work. */
617 gnttab_cancel_free_callback(&info->callback);
618 spin_unlock_irqrestore(&blkif_io_lock, flags);
619
620 /* Flush gnttab callback work. Must be done with no locks held. */
621 flush_work_sync(&info->work);
622
623 del_gendisk(info->gd);
624
625 minor = info->gd->first_minor;
626 nr_minors = info->gd->minors;
627 xlbd_release_minors(minor, nr_minors);
628
629 blk_cleanup_queue(info->rq);
630 info->rq = NULL;
631
632 put_disk(info->gd);
633 info->gd = NULL;
634}
635
636static void kick_pending_request_queues(struct blkfront_info *info)
637{
638 if (!RING_FULL(&info->ring)) {
639 /* Re-enable calldowns. */
640 blk_start_queue(info->rq);
641 /* Kick things off immediately. */
642 do_blkif_request(info->rq);
643 }
644}
645
646static void blkif_restart_queue(struct work_struct *work)
647{
648 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
649
650 spin_lock_irq(&blkif_io_lock);
651 if (info->connected == BLKIF_STATE_CONNECTED)
652 kick_pending_request_queues(info);
653 spin_unlock_irq(&blkif_io_lock);
654}
655
656static void blkif_free(struct blkfront_info *info, int suspend)
657{
658 /* Prevent new requests being issued until we fix things up. */
659 spin_lock_irq(&blkif_io_lock);
660 info->connected = suspend ?
661 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
662 /* No more blkif_request(). */
663 if (info->rq)
664 blk_stop_queue(info->rq);
665 /* No more gnttab callback work. */
666 gnttab_cancel_free_callback(&info->callback);
667 spin_unlock_irq(&blkif_io_lock);
668
669 /* Flush gnttab callback work. Must be done with no locks held. */
670 flush_work_sync(&info->work);
671
672 /* Free resources associated with old device channel. */
673 if (info->ring_ref != GRANT_INVALID_REF) {
674 gnttab_end_foreign_access(info->ring_ref, 0,
675 (unsigned long)info->ring.sring);
676 info->ring_ref = GRANT_INVALID_REF;
677 info->ring.sring = NULL;
678 }
679 if (info->irq)
680 unbind_from_irqhandler(info->irq, info);
681 info->evtchn = info->irq = 0;
682
683}
684
685static void blkif_completion(struct blk_shadow *s)
686{
687 int i;
688 for (i = 0; i < s->req.nr_segments; i++)
689 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
690}
691
692static irqreturn_t blkif_interrupt(int irq, void *dev_id)
693{
694 struct request *req;
695 struct blkif_response *bret;
696 RING_IDX i, rp;
697 unsigned long flags;
698 struct blkfront_info *info = (struct blkfront_info *)dev_id;
699 int error;
700
701 spin_lock_irqsave(&blkif_io_lock, flags);
702
703 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
704 spin_unlock_irqrestore(&blkif_io_lock, flags);
705 return IRQ_HANDLED;
706 }
707
708 again:
709 rp = info->ring.sring->rsp_prod;
710 rmb(); /* Ensure we see queued responses up to 'rp'. */
711
712 for (i = info->ring.rsp_cons; i != rp; i++) {
713 unsigned long id;
714
715 bret = RING_GET_RESPONSE(&info->ring, i);
716 id = bret->id;
717 req = info->shadow[id].request;
718
719 blkif_completion(&info->shadow[id]);
720
721 add_id_to_freelist(info, id);
722
723 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
724 switch (bret->operation) {
725 case BLKIF_OP_FLUSH_DISKCACHE:
726 case BLKIF_OP_WRITE_BARRIER:
727 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
728 printk(KERN_WARNING "blkfront: %s: write %s op failed\n",
729 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
730 "barrier" : "flush disk cache",
731 info->gd->disk_name);
732 error = -EOPNOTSUPP;
733 }
734 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
735 info->shadow[id].req.nr_segments == 0)) {
736 printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
737 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
738 "barrier" : "flush disk cache",
739 info->gd->disk_name);
740 error = -EOPNOTSUPP;
741 }
742 if (unlikely(error)) {
743 if (error == -EOPNOTSUPP)
744 error = 0;
745 info->feature_flush = 0;
746 info->flush_op = 0;
747 xlvbd_flush(info);
748 }
749 /* fall through */
750 case BLKIF_OP_READ:
751 case BLKIF_OP_WRITE:
752 if (unlikely(bret->status != BLKIF_RSP_OKAY))
753 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
754 "request: %x\n", bret->status);
755
756 __blk_end_request_all(req, error);
757 break;
758 default:
759 BUG();
760 }
761 }
762
763 info->ring.rsp_cons = i;
764
765 if (i != info->ring.req_prod_pvt) {
766 int more_to_do;
767 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
768 if (more_to_do)
769 goto again;
770 } else
771 info->ring.sring->rsp_event = i + 1;
772
773 kick_pending_request_queues(info);
774
775 spin_unlock_irqrestore(&blkif_io_lock, flags);
776
777 return IRQ_HANDLED;
778}
779
780
781static int setup_blkring(struct xenbus_device *dev,
782 struct blkfront_info *info)
783{
784 struct blkif_sring *sring;
785 int err;
786
787 info->ring_ref = GRANT_INVALID_REF;
788
789 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
790 if (!sring) {
791 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
792 return -ENOMEM;
793 }
794 SHARED_RING_INIT(sring);
795 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
796
797 sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
798
799 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
800 if (err < 0) {
801 free_page((unsigned long)sring);
802 info->ring.sring = NULL;
803 goto fail;
804 }
805 info->ring_ref = err;
806
807 err = xenbus_alloc_evtchn(dev, &info->evtchn);
808 if (err)
809 goto fail;
810
811 err = bind_evtchn_to_irqhandler(info->evtchn,
812 blkif_interrupt,
813 IRQF_SAMPLE_RANDOM, "blkif", info);
814 if (err <= 0) {
815 xenbus_dev_fatal(dev, err,
816 "bind_evtchn_to_irqhandler failed");
817 goto fail;
818 }
819 info->irq = err;
820
821 return 0;
822fail:
823 blkif_free(info, 0);
824 return err;
825}
826
827
828/* Common code used when first setting up, and when resuming. */
829static int talk_to_blkback(struct xenbus_device *dev,
830 struct blkfront_info *info)
831{
832 const char *message = NULL;
833 struct xenbus_transaction xbt;
834 int err;
835
836 /* Create shared ring, alloc event channel. */
837 err = setup_blkring(dev, info);
838 if (err)
839 goto out;
840
841again:
842 err = xenbus_transaction_start(&xbt);
843 if (err) {
844 xenbus_dev_fatal(dev, err, "starting transaction");
845 goto destroy_blkring;
846 }
847
848 err = xenbus_printf(xbt, dev->nodename,
849 "ring-ref", "%u", info->ring_ref);
850 if (err) {
851 message = "writing ring-ref";
852 goto abort_transaction;
853 }
854 err = xenbus_printf(xbt, dev->nodename,
855 "event-channel", "%u", info->evtchn);
856 if (err) {
857 message = "writing event-channel";
858 goto abort_transaction;
859 }
860 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
861 XEN_IO_PROTO_ABI_NATIVE);
862 if (err) {
863 message = "writing protocol";
864 goto abort_transaction;
865 }
866
867 err = xenbus_transaction_end(xbt, 0);
868 if (err) {
869 if (err == -EAGAIN)
870 goto again;
871 xenbus_dev_fatal(dev, err, "completing transaction");
872 goto destroy_blkring;
873 }
874
875 xenbus_switch_state(dev, XenbusStateInitialised);
876
877 return 0;
878
879 abort_transaction:
880 xenbus_transaction_end(xbt, 1);
881 if (message)
882 xenbus_dev_fatal(dev, err, "%s", message);
883 destroy_blkring:
884 blkif_free(info, 0);
885 out:
886 return err;
887}
888
889/**
890 * Entry point to this code when a new device is created. Allocate the basic
891 * structures and the ring buffer for communication with the backend, and
892 * inform the backend of the appropriate details for those. Switch to
893 * Initialised state.
894 */
895static int blkfront_probe(struct xenbus_device *dev,
896 const struct xenbus_device_id *id)
897{
898 int err, vdevice, i;
899 struct blkfront_info *info;
900
901 /* FIXME: Use dynamic device id if this is not set. */
902 err = xenbus_scanf(XBT_NIL, dev->nodename,
903 "virtual-device", "%i", &vdevice);
904 if (err != 1) {
905 /* go looking in the extended area instead */
906 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
907 "%i", &vdevice);
908 if (err != 1) {
909 xenbus_dev_fatal(dev, err, "reading virtual-device");
910 return err;
911 }
912 }
913
914 if (xen_hvm_domain()) {
915 char *type;
916 int len;
917 /* no unplug has been done: do not hook devices != xen vbds */
918 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
919 int major;
920
921 if (!VDEV_IS_EXTENDED(vdevice))
922 major = BLKIF_MAJOR(vdevice);
923 else
924 major = XENVBD_MAJOR;
925
926 if (major != XENVBD_MAJOR) {
927 printk(KERN_INFO
928 "%s: HVM does not support vbd %d as xen block device\n",
929 __FUNCTION__, vdevice);
930 return -ENODEV;
931 }
932 }
933 /* do not create a PV cdrom device if we are an HVM guest */
934 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
935 if (IS_ERR(type))
936 return -ENODEV;
937 if (strncmp(type, "cdrom", 5) == 0) {
938 kfree(type);
939 return -ENODEV;
940 }
941 kfree(type);
942 }
943 info = kzalloc(sizeof(*info), GFP_KERNEL);
944 if (!info) {
945 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
946 return -ENOMEM;
947 }
948
949 mutex_init(&info->mutex);
950 info->xbdev = dev;
951 info->vdevice = vdevice;
952 info->connected = BLKIF_STATE_DISCONNECTED;
953 INIT_WORK(&info->work, blkif_restart_queue);
954
955 for (i = 0; i < BLK_RING_SIZE; i++)
956 info->shadow[i].req.id = i+1;
957 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
958
959 /* Front end dir is a number, which is used as the id. */
960 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
961 dev_set_drvdata(&dev->dev, info);
962
963 err = talk_to_blkback(dev, info);
964 if (err) {
965 kfree(info);
966 dev_set_drvdata(&dev->dev, NULL);
967 return err;
968 }
969
970 return 0;
971}
972
973
974static int blkif_recover(struct blkfront_info *info)
975{
976 int i;
977 struct blkif_request *req;
978 struct blk_shadow *copy;
979 int j;
980
981 /* Stage 1: Make a safe copy of the shadow state. */
982 copy = kmalloc(sizeof(info->shadow),
983 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
984 if (!copy)
985 return -ENOMEM;
986 memcpy(copy, info->shadow, sizeof(info->shadow));
987
988 /* Stage 2: Set up free list. */
989 memset(&info->shadow, 0, sizeof(info->shadow));
990 for (i = 0; i < BLK_RING_SIZE; i++)
991 info->shadow[i].req.id = i+1;
992 info->shadow_free = info->ring.req_prod_pvt;
993 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
994
995 /* Stage 3: Find pending requests and requeue them. */
996 for (i = 0; i < BLK_RING_SIZE; i++) {
997 /* Not in use? */
998 if (!copy[i].request)
999 continue;
1000
1001 /* Grab a request slot and copy shadow state into it. */
1002 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
1003 *req = copy[i].req;
1004
1005 /* We get a new request id, and must reset the shadow state. */
1006 req->id = get_id_from_freelist(info);
1007 memcpy(&info->shadow[req->id], ©[i], sizeof(copy[i]));
1008
1009 /* Rewrite any grant references invalidated by susp/resume. */
1010 for (j = 0; j < req->nr_segments; j++)
1011 gnttab_grant_foreign_access_ref(
1012 req->u.rw.seg[j].gref,
1013 info->xbdev->otherend_id,
1014 pfn_to_mfn(info->shadow[req->id].frame[j]),
1015 rq_data_dir(info->shadow[req->id].request));
1016 info->shadow[req->id].req = *req;
1017
1018 info->ring.req_prod_pvt++;
1019 }
1020
1021 kfree(copy);
1022
1023 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1024
1025 spin_lock_irq(&blkif_io_lock);
1026
1027 /* Now safe for us to use the shared ring */
1028 info->connected = BLKIF_STATE_CONNECTED;
1029
1030 /* Send off requeued requests */
1031 flush_requests(info);
1032
1033 /* Kick any other new requests queued since we resumed */
1034 kick_pending_request_queues(info);
1035
1036 spin_unlock_irq(&blkif_io_lock);
1037
1038 return 0;
1039}
1040
1041/**
1042 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1043 * driver restart. We tear down our blkif structure and recreate it, but
1044 * leave the device-layer structures intact so that this is transparent to the
1045 * rest of the kernel.
1046 */
1047static int blkfront_resume(struct xenbus_device *dev)
1048{
1049 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1050 int err;
1051
1052 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1053
1054 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1055
1056 err = talk_to_blkback(dev, info);
1057 if (info->connected == BLKIF_STATE_SUSPENDED && !err)
1058 err = blkif_recover(info);
1059
1060 return err;
1061}
1062
1063static void
1064blkfront_closing(struct blkfront_info *info)
1065{
1066 struct xenbus_device *xbdev = info->xbdev;
1067 struct block_device *bdev = NULL;
1068
1069 mutex_lock(&info->mutex);
1070
1071 if (xbdev->state == XenbusStateClosing) {
1072 mutex_unlock(&info->mutex);
1073 return;
1074 }
1075
1076 if (info->gd)
1077 bdev = bdget_disk(info->gd, 0);
1078
1079 mutex_unlock(&info->mutex);
1080
1081 if (!bdev) {
1082 xenbus_frontend_closed(xbdev);
1083 return;
1084 }
1085
1086 mutex_lock(&bdev->bd_mutex);
1087
1088 if (bdev->bd_openers) {
1089 xenbus_dev_error(xbdev, -EBUSY,
1090 "Device in use; refusing to close");
1091 xenbus_switch_state(xbdev, XenbusStateClosing);
1092 } else {
1093 xlvbd_release_gendisk(info);
1094 xenbus_frontend_closed(xbdev);
1095 }
1096
1097 mutex_unlock(&bdev->bd_mutex);
1098 bdput(bdev);
1099}
1100
1101/*
1102 * Invoked when the backend is finally 'ready' (and has told produced
1103 * the details about the physical device - #sectors, size, etc).
1104 */
1105static void blkfront_connect(struct blkfront_info *info)
1106{
1107 unsigned long long sectors;
1108 unsigned long sector_size;
1109 unsigned int binfo;
1110 int err;
1111 int barrier, flush;
1112
1113 switch (info->connected) {
1114 case BLKIF_STATE_CONNECTED:
1115 /*
1116 * Potentially, the back-end may be signalling
1117 * a capacity change; update the capacity.
1118 */
1119 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1120 "sectors", "%Lu", §ors);
1121 if (XENBUS_EXIST_ERR(err))
1122 return;
1123 printk(KERN_INFO "Setting capacity to %Lu\n",
1124 sectors);
1125 set_capacity(info->gd, sectors);
1126 revalidate_disk(info->gd);
1127
1128 /* fall through */
1129 case BLKIF_STATE_SUSPENDED:
1130 return;
1131
1132 default:
1133 break;
1134 }
1135
1136 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1137 __func__, info->xbdev->otherend);
1138
1139 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1140 "sectors", "%llu", §ors,
1141 "info", "%u", &binfo,
1142 "sector-size", "%lu", §or_size,
1143 NULL);
1144 if (err) {
1145 xenbus_dev_fatal(info->xbdev, err,
1146 "reading backend fields at %s",
1147 info->xbdev->otherend);
1148 return;
1149 }
1150
1151 info->feature_flush = 0;
1152 info->flush_op = 0;
1153
1154 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1155 "feature-barrier", "%d", &barrier,
1156 NULL);
1157
1158 /*
1159 * If there's no "feature-barrier" defined, then it means
1160 * we're dealing with a very old backend which writes
1161 * synchronously; nothing to do.
1162 *
1163 * If there are barriers, then we use flush.
1164 */
1165 if (!err && barrier) {
1166 info->feature_flush = REQ_FLUSH | REQ_FUA;
1167 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1168 }
1169 /*
1170 * And if there is "feature-flush-cache" use that above
1171 * barriers.
1172 */
1173 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1174 "feature-flush-cache", "%d", &flush,
1175 NULL);
1176
1177 if (!err && flush) {
1178 info->feature_flush = REQ_FLUSH;
1179 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1180 }
1181
1182 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1183 if (err) {
1184 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1185 info->xbdev->otherend);
1186 return;
1187 }
1188
1189 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1190
1191 /* Kick pending requests. */
1192 spin_lock_irq(&blkif_io_lock);
1193 info->connected = BLKIF_STATE_CONNECTED;
1194 kick_pending_request_queues(info);
1195 spin_unlock_irq(&blkif_io_lock);
1196
1197 add_disk(info->gd);
1198
1199 info->is_ready = 1;
1200}
1201
1202/**
1203 * Callback received when the backend's state changes.
1204 */
1205static void blkback_changed(struct xenbus_device *dev,
1206 enum xenbus_state backend_state)
1207{
1208 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1209
1210 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1211
1212 switch (backend_state) {
1213 case XenbusStateInitialising:
1214 case XenbusStateInitWait:
1215 case XenbusStateInitialised:
1216 case XenbusStateReconfiguring:
1217 case XenbusStateReconfigured:
1218 case XenbusStateUnknown:
1219 case XenbusStateClosed:
1220 break;
1221
1222 case XenbusStateConnected:
1223 blkfront_connect(info);
1224 break;
1225
1226 case XenbusStateClosing:
1227 blkfront_closing(info);
1228 break;
1229 }
1230}
1231
1232static int blkfront_remove(struct xenbus_device *xbdev)
1233{
1234 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1235 struct block_device *bdev = NULL;
1236 struct gendisk *disk;
1237
1238 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1239
1240 blkif_free(info, 0);
1241
1242 mutex_lock(&info->mutex);
1243
1244 disk = info->gd;
1245 if (disk)
1246 bdev = bdget_disk(disk, 0);
1247
1248 info->xbdev = NULL;
1249 mutex_unlock(&info->mutex);
1250
1251 if (!bdev) {
1252 kfree(info);
1253 return 0;
1254 }
1255
1256 /*
1257 * The xbdev was removed before we reached the Closed
1258 * state. See if it's safe to remove the disk. If the bdev
1259 * isn't closed yet, we let release take care of it.
1260 */
1261
1262 mutex_lock(&bdev->bd_mutex);
1263 info = disk->private_data;
1264
1265 dev_warn(disk_to_dev(disk),
1266 "%s was hot-unplugged, %d stale handles\n",
1267 xbdev->nodename, bdev->bd_openers);
1268
1269 if (info && !bdev->bd_openers) {
1270 xlvbd_release_gendisk(info);
1271 disk->private_data = NULL;
1272 kfree(info);
1273 }
1274
1275 mutex_unlock(&bdev->bd_mutex);
1276 bdput(bdev);
1277
1278 return 0;
1279}
1280
1281static int blkfront_is_ready(struct xenbus_device *dev)
1282{
1283 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1284
1285 return info->is_ready && info->xbdev;
1286}
1287
1288static int blkif_open(struct block_device *bdev, fmode_t mode)
1289{
1290 struct gendisk *disk = bdev->bd_disk;
1291 struct blkfront_info *info;
1292 int err = 0;
1293
1294 mutex_lock(&blkfront_mutex);
1295
1296 info = disk->private_data;
1297 if (!info) {
1298 /* xbdev gone */
1299 err = -ERESTARTSYS;
1300 goto out;
1301 }
1302
1303 mutex_lock(&info->mutex);
1304
1305 if (!info->gd)
1306 /* xbdev is closed */
1307 err = -ERESTARTSYS;
1308
1309 mutex_unlock(&info->mutex);
1310
1311out:
1312 mutex_unlock(&blkfront_mutex);
1313 return err;
1314}
1315
1316static int blkif_release(struct gendisk *disk, fmode_t mode)
1317{
1318 struct blkfront_info *info = disk->private_data;
1319 struct block_device *bdev;
1320 struct xenbus_device *xbdev;
1321
1322 mutex_lock(&blkfront_mutex);
1323
1324 bdev = bdget_disk(disk, 0);
1325 bdput(bdev);
1326
1327 if (bdev->bd_openers)
1328 goto out;
1329
1330 /*
1331 * Check if we have been instructed to close. We will have
1332 * deferred this request, because the bdev was still open.
1333 */
1334
1335 mutex_lock(&info->mutex);
1336 xbdev = info->xbdev;
1337
1338 if (xbdev && xbdev->state == XenbusStateClosing) {
1339 /* pending switch to state closed */
1340 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1341 xlvbd_release_gendisk(info);
1342 xenbus_frontend_closed(info->xbdev);
1343 }
1344
1345 mutex_unlock(&info->mutex);
1346
1347 if (!xbdev) {
1348 /* sudden device removal */
1349 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1350 xlvbd_release_gendisk(info);
1351 disk->private_data = NULL;
1352 kfree(info);
1353 }
1354
1355out:
1356 mutex_unlock(&blkfront_mutex);
1357 return 0;
1358}
1359
1360static const struct block_device_operations xlvbd_block_fops =
1361{
1362 .owner = THIS_MODULE,
1363 .open = blkif_open,
1364 .release = blkif_release,
1365 .getgeo = blkif_getgeo,
1366 .ioctl = blkif_ioctl,
1367};
1368
1369
1370static const struct xenbus_device_id blkfront_ids[] = {
1371 { "vbd" },
1372 { "" }
1373};
1374
1375static struct xenbus_driver blkfront = {
1376 .name = "vbd",
1377 .owner = THIS_MODULE,
1378 .ids = blkfront_ids,
1379 .probe = blkfront_probe,
1380 .remove = blkfront_remove,
1381 .resume = blkfront_resume,
1382 .otherend_changed = blkback_changed,
1383 .is_ready = blkfront_is_ready,
1384};
1385
1386static int __init xlblk_init(void)
1387{
1388 if (!xen_domain())
1389 return -ENODEV;
1390
1391 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1392 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1393 XENVBD_MAJOR, DEV_NAME);
1394 return -ENODEV;
1395 }
1396
1397 return xenbus_register_frontend(&blkfront);
1398}
1399module_init(xlblk_init);
1400
1401
1402static void __exit xlblk_exit(void)
1403{
1404 return xenbus_unregister_driver(&blkfront);
1405}
1406module_exit(xlblk_exit);
1407
1408MODULE_DESCRIPTION("Xen virtual block device frontend");
1409MODULE_LICENSE("GPL");
1410MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1411MODULE_ALIAS("xen:vbd");
1412MODULE_ALIAS("xenblk");
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
79enum blkif_state {
80 BLKIF_STATE_DISCONNECTED,
81 BLKIF_STATE_CONNECTED,
82 BLKIF_STATE_SUSPENDED,
83};
84
85struct grant {
86 grant_ref_t gref;
87 struct page *page;
88 struct list_head node;
89};
90
91enum blk_req_status {
92 REQ_WAITING,
93 REQ_DONE,
94 REQ_ERROR,
95 REQ_EOPNOTSUPP,
96};
97
98struct 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
115struct blkif_req {
116 blk_status_t error;
117};
118
119static inline struct blkif_req *blkif_req(struct request *rq)
120{
121 return blk_mq_rq_to_pdu(rq);
122}
123
124static DEFINE_MUTEX(blkfront_mutex);
125static const struct block_device_operations xlvbd_block_fops;
126static struct delayed_work blkfront_work;
127static 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
135static unsigned int xen_blkif_max_segments = 32;
136module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
137MODULE_PARM_DESC(max_indirect_segments,
138 "Maximum amount of segments in indirect requests (default is 32)");
139
140static unsigned int xen_blkif_max_queues = 4;
141module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
142MODULE_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 */
148static unsigned int xen_blkif_max_ring_order;
149module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
150MODULE_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 */
170struct 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 */
191struct 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
224static unsigned int nr_minors;
225static unsigned long *minors;
226static 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
260static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
261static void blkfront_gather_backend_features(struct blkfront_info *info);
262static 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
269static inline struct blkfront_ring_info *
270get_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
276static 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
286static 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
299static 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
327out_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
340static 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
355static 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
364static 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
389static 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
416static 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}
433static 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
470static 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
480static 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
486static 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
502static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
503 unsigned command, unsigned long argument)
504{
505 int i;
506
507 switch (command) {
508 case CDROMMULTISESSION:
509 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
510 if (put_user(0, (char __user *)(argument + i)))
511 return -EFAULT;
512 return 0;
513 case CDROM_GET_CAPABILITY:
514 if (bdev->bd_disk->flags & GENHD_FL_CD)
515 return 0;
516 return -EINVAL;
517 default:
518 return -EINVAL;
519 }
520}
521
522static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
523 struct request *req,
524 struct blkif_request **ring_req)
525{
526 unsigned long id;
527
528 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
529 rinfo->ring.req_prod_pvt++;
530
531 id = get_id_from_freelist(rinfo);
532 rinfo->shadow[id].request = req;
533 rinfo->shadow[id].status = REQ_WAITING;
534 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
535
536 (*ring_req)->u.rw.id = id;
537
538 return id;
539}
540
541static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
542{
543 struct blkfront_info *info = rinfo->dev_info;
544 struct blkif_request *ring_req;
545 unsigned long id;
546
547 /* Fill out a communications ring structure. */
548 id = blkif_ring_get_request(rinfo, req, &ring_req);
549
550 ring_req->operation = BLKIF_OP_DISCARD;
551 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
552 ring_req->u.discard.id = id;
553 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
554 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
555 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
556 else
557 ring_req->u.discard.flag = 0;
558
559 /* Keep a private copy so we can reissue requests when recovering. */
560 rinfo->shadow[id].req = *ring_req;
561
562 return 0;
563}
564
565struct setup_rw_req {
566 unsigned int grant_idx;
567 struct blkif_request_segment *segments;
568 struct blkfront_ring_info *rinfo;
569 struct blkif_request *ring_req;
570 grant_ref_t gref_head;
571 unsigned int id;
572 /* Only used when persistent grant is used and it's a read request */
573 bool need_copy;
574 unsigned int bvec_off;
575 char *bvec_data;
576
577 bool require_extra_req;
578 struct blkif_request *extra_ring_req;
579};
580
581static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
582 unsigned int len, void *data)
583{
584 struct setup_rw_req *setup = data;
585 int n, ref;
586 struct grant *gnt_list_entry;
587 unsigned int fsect, lsect;
588 /* Convenient aliases */
589 unsigned int grant_idx = setup->grant_idx;
590 struct blkif_request *ring_req = setup->ring_req;
591 struct blkfront_ring_info *rinfo = setup->rinfo;
592 /*
593 * We always use the shadow of the first request to store the list
594 * of grant associated to the block I/O request. This made the
595 * completion more easy to handle even if the block I/O request is
596 * split.
597 */
598 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
599
600 if (unlikely(setup->require_extra_req &&
601 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
602 /*
603 * We are using the second request, setup grant_idx
604 * to be the index of the segment array.
605 */
606 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
607 ring_req = setup->extra_ring_req;
608 }
609
610 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
611 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
612 if (setup->segments)
613 kunmap_atomic(setup->segments);
614
615 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
616 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
617 shadow->indirect_grants[n] = gnt_list_entry;
618 setup->segments = kmap_atomic(gnt_list_entry->page);
619 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
620 }
621
622 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
623 ref = gnt_list_entry->gref;
624 /*
625 * All the grants are stored in the shadow of the first
626 * request. Therefore we have to use the global index.
627 */
628 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
629
630 if (setup->need_copy) {
631 void *shared_data;
632
633 shared_data = kmap_atomic(gnt_list_entry->page);
634 /*
635 * this does not wipe data stored outside the
636 * range sg->offset..sg->offset+sg->length.
637 * Therefore, blkback *could* see data from
638 * previous requests. This is OK as long as
639 * persistent grants are shared with just one
640 * domain. It may need refactoring if this
641 * changes
642 */
643 memcpy(shared_data + offset,
644 setup->bvec_data + setup->bvec_off,
645 len);
646
647 kunmap_atomic(shared_data);
648 setup->bvec_off += len;
649 }
650
651 fsect = offset >> 9;
652 lsect = fsect + (len >> 9) - 1;
653 if (ring_req->operation != BLKIF_OP_INDIRECT) {
654 ring_req->u.rw.seg[grant_idx] =
655 (struct blkif_request_segment) {
656 .gref = ref,
657 .first_sect = fsect,
658 .last_sect = lsect };
659 } else {
660 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
661 (struct blkif_request_segment) {
662 .gref = ref,
663 .first_sect = fsect,
664 .last_sect = lsect };
665 }
666
667 (setup->grant_idx)++;
668}
669
670static void blkif_setup_extra_req(struct blkif_request *first,
671 struct blkif_request *second)
672{
673 uint16_t nr_segments = first->u.rw.nr_segments;
674
675 /*
676 * The second request is only present when the first request uses
677 * all its segments. It's always the continuity of the first one.
678 */
679 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
680
681 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
682 second->u.rw.sector_number = first->u.rw.sector_number +
683 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
684
685 second->u.rw.handle = first->u.rw.handle;
686 second->operation = first->operation;
687}
688
689static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
690{
691 struct blkfront_info *info = rinfo->dev_info;
692 struct blkif_request *ring_req, *extra_ring_req = NULL;
693 unsigned long id, extra_id = NO_ASSOCIATED_ID;
694 bool require_extra_req = false;
695 int i;
696 struct setup_rw_req setup = {
697 .grant_idx = 0,
698 .segments = NULL,
699 .rinfo = rinfo,
700 .need_copy = rq_data_dir(req) && info->feature_persistent,
701 };
702
703 /*
704 * Used to store if we are able to queue the request by just using
705 * existing persistent grants, or if we have to get new grants,
706 * as there are not sufficiently many free.
707 */
708 bool new_persistent_gnts = false;
709 struct scatterlist *sg;
710 int num_sg, max_grefs, num_grant;
711
712 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
713 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
714 /*
715 * If we are using indirect segments we need to account
716 * for the indirect grefs used in the request.
717 */
718 max_grefs += INDIRECT_GREFS(max_grefs);
719
720 /* Check if we have enough persistent grants to allocate a requests */
721 if (rinfo->persistent_gnts_c < max_grefs) {
722 new_persistent_gnts = true;
723
724 if (gnttab_alloc_grant_references(
725 max_grefs - rinfo->persistent_gnts_c,
726 &setup.gref_head) < 0) {
727 gnttab_request_free_callback(
728 &rinfo->callback,
729 blkif_restart_queue_callback,
730 rinfo,
731 max_grefs - rinfo->persistent_gnts_c);
732 return 1;
733 }
734 }
735
736 /* Fill out a communications ring structure. */
737 id = blkif_ring_get_request(rinfo, req, &ring_req);
738
739 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
740 num_grant = 0;
741 /* Calculate the number of grant used */
742 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
743 num_grant += gnttab_count_grant(sg->offset, sg->length);
744
745 require_extra_req = info->max_indirect_segments == 0 &&
746 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
747 BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
748
749 rinfo->shadow[id].num_sg = num_sg;
750 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
751 likely(!require_extra_req)) {
752 /*
753 * The indirect operation can only be a BLKIF_OP_READ or
754 * BLKIF_OP_WRITE
755 */
756 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
757 ring_req->operation = BLKIF_OP_INDIRECT;
758 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
759 BLKIF_OP_WRITE : BLKIF_OP_READ;
760 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
761 ring_req->u.indirect.handle = info->handle;
762 ring_req->u.indirect.nr_segments = num_grant;
763 } else {
764 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
765 ring_req->u.rw.handle = info->handle;
766 ring_req->operation = rq_data_dir(req) ?
767 BLKIF_OP_WRITE : BLKIF_OP_READ;
768 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
769 /*
770 * Ideally we can do an unordered flush-to-disk.
771 * In case the backend onlysupports barriers, use that.
772 * A barrier request a superset of FUA, so we can
773 * implement it the same way. (It's also a FLUSH+FUA,
774 * since it is guaranteed ordered WRT previous writes.)
775 */
776 if (info->feature_flush && info->feature_fua)
777 ring_req->operation =
778 BLKIF_OP_WRITE_BARRIER;
779 else if (info->feature_flush)
780 ring_req->operation =
781 BLKIF_OP_FLUSH_DISKCACHE;
782 else
783 ring_req->operation = 0;
784 }
785 ring_req->u.rw.nr_segments = num_grant;
786 if (unlikely(require_extra_req)) {
787 extra_id = blkif_ring_get_request(rinfo, req,
788 &extra_ring_req);
789 /*
790 * Only the first request contains the scatter-gather
791 * list.
792 */
793 rinfo->shadow[extra_id].num_sg = 0;
794
795 blkif_setup_extra_req(ring_req, extra_ring_req);
796
797 /* Link the 2 requests together */
798 rinfo->shadow[extra_id].associated_id = id;
799 rinfo->shadow[id].associated_id = extra_id;
800 }
801 }
802
803 setup.ring_req = ring_req;
804 setup.id = id;
805
806 setup.require_extra_req = require_extra_req;
807 if (unlikely(require_extra_req))
808 setup.extra_ring_req = extra_ring_req;
809
810 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
811 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
812
813 if (setup.need_copy) {
814 setup.bvec_off = sg->offset;
815 setup.bvec_data = kmap_atomic(sg_page(sg));
816 }
817
818 gnttab_foreach_grant_in_range(sg_page(sg),
819 sg->offset,
820 sg->length,
821 blkif_setup_rw_req_grant,
822 &setup);
823
824 if (setup.need_copy)
825 kunmap_atomic(setup.bvec_data);
826 }
827 if (setup.segments)
828 kunmap_atomic(setup.segments);
829
830 /* Keep a private copy so we can reissue requests when recovering. */
831 rinfo->shadow[id].req = *ring_req;
832 if (unlikely(require_extra_req))
833 rinfo->shadow[extra_id].req = *extra_ring_req;
834
835 if (new_persistent_gnts)
836 gnttab_free_grant_references(setup.gref_head);
837
838 return 0;
839}
840
841/*
842 * Generate a Xen blkfront IO request from a blk layer request. Reads
843 * and writes are handled as expected.
844 *
845 * @req: a request struct
846 */
847static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
848{
849 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
850 return 1;
851
852 if (unlikely(req_op(req) == REQ_OP_DISCARD ||
853 req_op(req) == REQ_OP_SECURE_ERASE))
854 return blkif_queue_discard_req(req, rinfo);
855 else
856 return blkif_queue_rw_req(req, rinfo);
857}
858
859static inline void flush_requests(struct blkfront_ring_info *rinfo)
860{
861 int notify;
862
863 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
864
865 if (notify)
866 notify_remote_via_irq(rinfo->irq);
867}
868
869static inline bool blkif_request_flush_invalid(struct request *req,
870 struct blkfront_info *info)
871{
872 return (blk_rq_is_passthrough(req) ||
873 ((req_op(req) == REQ_OP_FLUSH) &&
874 !info->feature_flush) ||
875 ((req->cmd_flags & REQ_FUA) &&
876 !info->feature_fua));
877}
878
879static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
880 const struct blk_mq_queue_data *qd)
881{
882 unsigned long flags;
883 int qid = hctx->queue_num;
884 struct blkfront_info *info = hctx->queue->queuedata;
885 struct blkfront_ring_info *rinfo = NULL;
886
887 rinfo = get_rinfo(info, qid);
888 blk_mq_start_request(qd->rq);
889 spin_lock_irqsave(&rinfo->ring_lock, flags);
890 if (RING_FULL(&rinfo->ring))
891 goto out_busy;
892
893 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
894 goto out_err;
895
896 if (blkif_queue_request(qd->rq, rinfo))
897 goto out_busy;
898
899 flush_requests(rinfo);
900 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
901 return BLK_STS_OK;
902
903out_err:
904 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
905 return BLK_STS_IOERR;
906
907out_busy:
908 blk_mq_stop_hw_queue(hctx);
909 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
910 return BLK_STS_DEV_RESOURCE;
911}
912
913static void blkif_complete_rq(struct request *rq)
914{
915 blk_mq_end_request(rq, blkif_req(rq)->error);
916}
917
918static const struct blk_mq_ops blkfront_mq_ops = {
919 .queue_rq = blkif_queue_rq,
920 .complete = blkif_complete_rq,
921};
922
923static void blkif_set_queue_limits(struct blkfront_info *info)
924{
925 struct request_queue *rq = info->rq;
926 struct gendisk *gd = info->gd;
927 unsigned int segments = info->max_indirect_segments ? :
928 BLKIF_MAX_SEGMENTS_PER_REQUEST;
929
930 blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
931
932 if (info->feature_discard) {
933 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
934 blk_queue_max_discard_sectors(rq, get_capacity(gd));
935 rq->limits.discard_granularity = info->discard_granularity ?:
936 info->physical_sector_size;
937 rq->limits.discard_alignment = info->discard_alignment;
938 if (info->feature_secdiscard)
939 blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
940 }
941
942 /* Hard sector size and max sectors impersonate the equiv. hardware. */
943 blk_queue_logical_block_size(rq, info->sector_size);
944 blk_queue_physical_block_size(rq, info->physical_sector_size);
945 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
946
947 /* Each segment in a request is up to an aligned page in size. */
948 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
949 blk_queue_max_segment_size(rq, PAGE_SIZE);
950
951 /* Ensure a merged request will fit in a single I/O ring slot. */
952 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
953
954 /* Make sure buffer addresses are sector-aligned. */
955 blk_queue_dma_alignment(rq, 511);
956}
957
958static const char *flush_info(struct blkfront_info *info)
959{
960 if (info->feature_flush && info->feature_fua)
961 return "barrier: enabled;";
962 else if (info->feature_flush)
963 return "flush diskcache: enabled;";
964 else
965 return "barrier or flush: disabled;";
966}
967
968static void xlvbd_flush(struct blkfront_info *info)
969{
970 blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
971 info->feature_fua ? true : false);
972 pr_info("blkfront: %s: %s %s %s %s %s\n",
973 info->gd->disk_name, flush_info(info),
974 "persistent grants:", info->feature_persistent ?
975 "enabled;" : "disabled;", "indirect descriptors:",
976 info->max_indirect_segments ? "enabled;" : "disabled;");
977}
978
979static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
980{
981 int major;
982 major = BLKIF_MAJOR(vdevice);
983 *minor = BLKIF_MINOR(vdevice);
984 switch (major) {
985 case XEN_IDE0_MAJOR:
986 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
987 *minor = ((*minor / 64) * PARTS_PER_DISK) +
988 EMULATED_HD_DISK_MINOR_OFFSET;
989 break;
990 case XEN_IDE1_MAJOR:
991 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
992 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
993 EMULATED_HD_DISK_MINOR_OFFSET;
994 break;
995 case XEN_SCSI_DISK0_MAJOR:
996 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
997 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
998 break;
999 case XEN_SCSI_DISK1_MAJOR:
1000 case XEN_SCSI_DISK2_MAJOR:
1001 case XEN_SCSI_DISK3_MAJOR:
1002 case XEN_SCSI_DISK4_MAJOR:
1003 case XEN_SCSI_DISK5_MAJOR:
1004 case XEN_SCSI_DISK6_MAJOR:
1005 case XEN_SCSI_DISK7_MAJOR:
1006 *offset = (*minor / PARTS_PER_DISK) +
1007 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1008 EMULATED_SD_DISK_NAME_OFFSET;
1009 *minor = *minor +
1010 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1011 EMULATED_SD_DISK_MINOR_OFFSET;
1012 break;
1013 case XEN_SCSI_DISK8_MAJOR:
1014 case XEN_SCSI_DISK9_MAJOR:
1015 case XEN_SCSI_DISK10_MAJOR:
1016 case XEN_SCSI_DISK11_MAJOR:
1017 case XEN_SCSI_DISK12_MAJOR:
1018 case XEN_SCSI_DISK13_MAJOR:
1019 case XEN_SCSI_DISK14_MAJOR:
1020 case XEN_SCSI_DISK15_MAJOR:
1021 *offset = (*minor / PARTS_PER_DISK) +
1022 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1023 EMULATED_SD_DISK_NAME_OFFSET;
1024 *minor = *minor +
1025 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1026 EMULATED_SD_DISK_MINOR_OFFSET;
1027 break;
1028 case XENVBD_MAJOR:
1029 *offset = *minor / PARTS_PER_DISK;
1030 break;
1031 default:
1032 printk(KERN_WARNING "blkfront: your disk configuration is "
1033 "incorrect, please use an xvd device instead\n");
1034 return -ENODEV;
1035 }
1036 return 0;
1037}
1038
1039static char *encode_disk_name(char *ptr, unsigned int n)
1040{
1041 if (n >= 26)
1042 ptr = encode_disk_name(ptr, n / 26 - 1);
1043 *ptr = 'a' + n % 26;
1044 return ptr + 1;
1045}
1046
1047static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1048 struct blkfront_info *info,
1049 u16 vdisk_info, u16 sector_size,
1050 unsigned int physical_sector_size)
1051{
1052 struct gendisk *gd;
1053 int nr_minors = 1;
1054 int err;
1055 unsigned int offset;
1056 int minor;
1057 int nr_parts;
1058 char *ptr;
1059
1060 BUG_ON(info->gd != NULL);
1061 BUG_ON(info->rq != NULL);
1062
1063 if ((info->vdevice>>EXT_SHIFT) > 1) {
1064 /* this is above the extended range; something is wrong */
1065 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1066 return -ENODEV;
1067 }
1068
1069 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1070 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1071 if (err)
1072 return err;
1073 nr_parts = PARTS_PER_DISK;
1074 } else {
1075 minor = BLKIF_MINOR_EXT(info->vdevice);
1076 nr_parts = PARTS_PER_EXT_DISK;
1077 offset = minor / nr_parts;
1078 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1079 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1080 "emulated IDE disks,\n\t choose an xvd device name"
1081 "from xvde on\n", info->vdevice);
1082 }
1083 if (minor >> MINORBITS) {
1084 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1085 info->vdevice, minor);
1086 return -ENODEV;
1087 }
1088
1089 if ((minor % nr_parts) == 0)
1090 nr_minors = nr_parts;
1091
1092 err = xlbd_reserve_minors(minor, nr_minors);
1093 if (err)
1094 return err;
1095 err = -ENODEV;
1096
1097 memset(&info->tag_set, 0, sizeof(info->tag_set));
1098 info->tag_set.ops = &blkfront_mq_ops;
1099 info->tag_set.nr_hw_queues = info->nr_rings;
1100 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
1101 /*
1102 * When indirect descriptior is not supported, the I/O request
1103 * will be split between multiple request in the ring.
1104 * To avoid problems when sending the request, divide by
1105 * 2 the depth of the queue.
1106 */
1107 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
1108 } else
1109 info->tag_set.queue_depth = BLK_RING_SIZE(info);
1110 info->tag_set.numa_node = NUMA_NO_NODE;
1111 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1112 info->tag_set.cmd_size = sizeof(struct blkif_req);
1113 info->tag_set.driver_data = info;
1114
1115 err = blk_mq_alloc_tag_set(&info->tag_set);
1116 if (err)
1117 goto out_release_minors;
1118
1119 gd = blk_mq_alloc_disk(&info->tag_set, info);
1120 if (IS_ERR(gd)) {
1121 err = PTR_ERR(gd);
1122 goto out_free_tag_set;
1123 }
1124
1125 strcpy(gd->disk_name, DEV_NAME);
1126 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1127 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1128 if (nr_minors > 1)
1129 *ptr = 0;
1130 else
1131 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1132 "%d", minor & (nr_parts - 1));
1133
1134 gd->major = XENVBD_MAJOR;
1135 gd->first_minor = minor;
1136 gd->minors = nr_minors;
1137 gd->fops = &xlvbd_block_fops;
1138 gd->private_data = info;
1139 set_capacity(gd, capacity);
1140
1141 info->rq = gd->queue;
1142 info->gd = gd;
1143 info->sector_size = sector_size;
1144 info->physical_sector_size = physical_sector_size;
1145 blkif_set_queue_limits(info);
1146
1147 xlvbd_flush(info);
1148
1149 if (vdisk_info & VDISK_READONLY)
1150 set_disk_ro(gd, 1);
1151
1152 if (vdisk_info & VDISK_REMOVABLE)
1153 gd->flags |= GENHD_FL_REMOVABLE;
1154
1155 if (vdisk_info & VDISK_CDROM)
1156 gd->flags |= GENHD_FL_CD;
1157
1158 return 0;
1159
1160out_free_tag_set:
1161 blk_mq_free_tag_set(&info->tag_set);
1162out_release_minors:
1163 xlbd_release_minors(minor, nr_minors);
1164 return err;
1165}
1166
1167/* Already hold rinfo->ring_lock. */
1168static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1169{
1170 if (!RING_FULL(&rinfo->ring))
1171 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1172}
1173
1174static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1175{
1176 unsigned long flags;
1177
1178 spin_lock_irqsave(&rinfo->ring_lock, flags);
1179 kick_pending_request_queues_locked(rinfo);
1180 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1181}
1182
1183static void blkif_restart_queue(struct work_struct *work)
1184{
1185 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1186
1187 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1188 kick_pending_request_queues(rinfo);
1189}
1190
1191static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1192{
1193 struct grant *persistent_gnt, *n;
1194 struct blkfront_info *info = rinfo->dev_info;
1195 int i, j, segs;
1196
1197 /*
1198 * Remove indirect pages, this only happens when using indirect
1199 * descriptors but not persistent grants
1200 */
1201 if (!list_empty(&rinfo->indirect_pages)) {
1202 struct page *indirect_page, *n;
1203
1204 BUG_ON(info->feature_persistent);
1205 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1206 list_del(&indirect_page->lru);
1207 __free_page(indirect_page);
1208 }
1209 }
1210
1211 /* Remove all persistent grants. */
1212 if (!list_empty(&rinfo->grants)) {
1213 list_for_each_entry_safe(persistent_gnt, n,
1214 &rinfo->grants, node) {
1215 list_del(&persistent_gnt->node);
1216 if (persistent_gnt->gref != GRANT_INVALID_REF) {
1217 gnttab_end_foreign_access(persistent_gnt->gref,
1218 0, 0UL);
1219 rinfo->persistent_gnts_c--;
1220 }
1221 if (info->feature_persistent)
1222 __free_page(persistent_gnt->page);
1223 kfree(persistent_gnt);
1224 }
1225 }
1226 BUG_ON(rinfo->persistent_gnts_c != 0);
1227
1228 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1229 /*
1230 * Clear persistent grants present in requests already
1231 * on the shared ring
1232 */
1233 if (!rinfo->shadow[i].request)
1234 goto free_shadow;
1235
1236 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1237 rinfo->shadow[i].req.u.indirect.nr_segments :
1238 rinfo->shadow[i].req.u.rw.nr_segments;
1239 for (j = 0; j < segs; j++) {
1240 persistent_gnt = rinfo->shadow[i].grants_used[j];
1241 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1242 if (info->feature_persistent)
1243 __free_page(persistent_gnt->page);
1244 kfree(persistent_gnt);
1245 }
1246
1247 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1248 /*
1249 * If this is not an indirect operation don't try to
1250 * free indirect segments
1251 */
1252 goto free_shadow;
1253
1254 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1255 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1256 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1257 __free_page(persistent_gnt->page);
1258 kfree(persistent_gnt);
1259 }
1260
1261free_shadow:
1262 kvfree(rinfo->shadow[i].grants_used);
1263 rinfo->shadow[i].grants_used = NULL;
1264 kvfree(rinfo->shadow[i].indirect_grants);
1265 rinfo->shadow[i].indirect_grants = NULL;
1266 kvfree(rinfo->shadow[i].sg);
1267 rinfo->shadow[i].sg = NULL;
1268 }
1269
1270 /* No more gnttab callback work. */
1271 gnttab_cancel_free_callback(&rinfo->callback);
1272
1273 /* Flush gnttab callback work. Must be done with no locks held. */
1274 flush_work(&rinfo->work);
1275
1276 /* Free resources associated with old device channel. */
1277 for (i = 0; i < info->nr_ring_pages; i++) {
1278 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1279 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1280 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1281 }
1282 }
1283 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1284 rinfo->ring.sring = NULL;
1285
1286 if (rinfo->irq)
1287 unbind_from_irqhandler(rinfo->irq, rinfo);
1288 rinfo->evtchn = rinfo->irq = 0;
1289}
1290
1291static void blkif_free(struct blkfront_info *info, int suspend)
1292{
1293 unsigned int i;
1294 struct blkfront_ring_info *rinfo;
1295
1296 /* Prevent new requests being issued until we fix things up. */
1297 info->connected = suspend ?
1298 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1299 /* No more blkif_request(). */
1300 if (info->rq)
1301 blk_mq_stop_hw_queues(info->rq);
1302
1303 for_each_rinfo(info, rinfo, i)
1304 blkif_free_ring(rinfo);
1305
1306 kvfree(info->rinfo);
1307 info->rinfo = NULL;
1308 info->nr_rings = 0;
1309}
1310
1311struct copy_from_grant {
1312 const struct blk_shadow *s;
1313 unsigned int grant_idx;
1314 unsigned int bvec_offset;
1315 char *bvec_data;
1316};
1317
1318static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1319 unsigned int len, void *data)
1320{
1321 struct copy_from_grant *info = data;
1322 char *shared_data;
1323 /* Convenient aliases */
1324 const struct blk_shadow *s = info->s;
1325
1326 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1327
1328 memcpy(info->bvec_data + info->bvec_offset,
1329 shared_data + offset, len);
1330
1331 info->bvec_offset += len;
1332 info->grant_idx++;
1333
1334 kunmap_atomic(shared_data);
1335}
1336
1337static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1338{
1339 switch (rsp)
1340 {
1341 case BLKIF_RSP_OKAY:
1342 return REQ_DONE;
1343 case BLKIF_RSP_EOPNOTSUPP:
1344 return REQ_EOPNOTSUPP;
1345 case BLKIF_RSP_ERROR:
1346 default:
1347 return REQ_ERROR;
1348 }
1349}
1350
1351/*
1352 * Get the final status of the block request based on two ring response
1353 */
1354static int blkif_get_final_status(enum blk_req_status s1,
1355 enum blk_req_status s2)
1356{
1357 BUG_ON(s1 == REQ_WAITING);
1358 BUG_ON(s2 == REQ_WAITING);
1359
1360 if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1361 return BLKIF_RSP_ERROR;
1362 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1363 return BLKIF_RSP_EOPNOTSUPP;
1364 return BLKIF_RSP_OKAY;
1365}
1366
1367static bool blkif_completion(unsigned long *id,
1368 struct blkfront_ring_info *rinfo,
1369 struct blkif_response *bret)
1370{
1371 int i = 0;
1372 struct scatterlist *sg;
1373 int num_sg, num_grant;
1374 struct blkfront_info *info = rinfo->dev_info;
1375 struct blk_shadow *s = &rinfo->shadow[*id];
1376 struct copy_from_grant data = {
1377 .grant_idx = 0,
1378 };
1379
1380 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1381 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1382
1383 /* The I/O request may be split in two. */
1384 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1385 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1386
1387 /* Keep the status of the current response in shadow. */
1388 s->status = blkif_rsp_to_req_status(bret->status);
1389
1390 /* Wait the second response if not yet here. */
1391 if (s2->status == REQ_WAITING)
1392 return false;
1393
1394 bret->status = blkif_get_final_status(s->status,
1395 s2->status);
1396
1397 /*
1398 * All the grants is stored in the first shadow in order
1399 * to make the completion code simpler.
1400 */
1401 num_grant += s2->req.u.rw.nr_segments;
1402
1403 /*
1404 * The two responses may not come in order. Only the
1405 * first request will store the scatter-gather list.
1406 */
1407 if (s2->num_sg != 0) {
1408 /* Update "id" with the ID of the first response. */
1409 *id = s->associated_id;
1410 s = s2;
1411 }
1412
1413 /*
1414 * We don't need anymore the second request, so recycling
1415 * it now.
1416 */
1417 if (add_id_to_freelist(rinfo, s->associated_id))
1418 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1419 info->gd->disk_name, s->associated_id);
1420 }
1421
1422 data.s = s;
1423 num_sg = s->num_sg;
1424
1425 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1426 for_each_sg(s->sg, sg, num_sg, i) {
1427 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1428
1429 data.bvec_offset = sg->offset;
1430 data.bvec_data = kmap_atomic(sg_page(sg));
1431
1432 gnttab_foreach_grant_in_range(sg_page(sg),
1433 sg->offset,
1434 sg->length,
1435 blkif_copy_from_grant,
1436 &data);
1437
1438 kunmap_atomic(data.bvec_data);
1439 }
1440 }
1441 /* Add the persistent grant into the list of free grants */
1442 for (i = 0; i < num_grant; i++) {
1443 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1444 /*
1445 * If the grant is still mapped by the backend (the
1446 * backend has chosen to make this grant persistent)
1447 * we add it at the head of the list, so it will be
1448 * reused first.
1449 */
1450 if (!info->feature_persistent)
1451 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1452 s->grants_used[i]->gref);
1453 list_add(&s->grants_used[i]->node, &rinfo->grants);
1454 rinfo->persistent_gnts_c++;
1455 } else {
1456 /*
1457 * If the grant is not mapped by the backend we end the
1458 * foreign access and add it to the tail of the list,
1459 * so it will not be picked again unless we run out of
1460 * persistent grants.
1461 */
1462 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1463 s->grants_used[i]->gref = GRANT_INVALID_REF;
1464 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1465 }
1466 }
1467 if (s->req.operation == BLKIF_OP_INDIRECT) {
1468 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1469 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1470 if (!info->feature_persistent)
1471 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1472 s->indirect_grants[i]->gref);
1473 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1474 rinfo->persistent_gnts_c++;
1475 } else {
1476 struct page *indirect_page;
1477
1478 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1479 /*
1480 * Add the used indirect page back to the list of
1481 * available pages for indirect grefs.
1482 */
1483 if (!info->feature_persistent) {
1484 indirect_page = s->indirect_grants[i]->page;
1485 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1486 }
1487 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1488 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1489 }
1490 }
1491 }
1492
1493 return true;
1494}
1495
1496static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1497{
1498 struct request *req;
1499 struct blkif_response *bret;
1500 RING_IDX i, rp;
1501 unsigned long flags;
1502 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1503 struct blkfront_info *info = rinfo->dev_info;
1504
1505 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1506 return IRQ_HANDLED;
1507
1508 spin_lock_irqsave(&rinfo->ring_lock, flags);
1509 again:
1510 rp = rinfo->ring.sring->rsp_prod;
1511 rmb(); /* Ensure we see queued responses up to 'rp'. */
1512
1513 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1514 unsigned long id;
1515
1516 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1517 id = bret->id;
1518 /*
1519 * The backend has messed up and given us an id that we would
1520 * never have given to it (we stamp it up to BLK_RING_SIZE -
1521 * look in get_id_from_freelist.
1522 */
1523 if (id >= BLK_RING_SIZE(info)) {
1524 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1525 info->gd->disk_name, op_name(bret->operation), id);
1526 /* We can't safely get the 'struct request' as
1527 * the id is busted. */
1528 continue;
1529 }
1530 req = rinfo->shadow[id].request;
1531
1532 if (bret->operation != BLKIF_OP_DISCARD) {
1533 /*
1534 * We may need to wait for an extra response if the
1535 * I/O request is split in 2
1536 */
1537 if (!blkif_completion(&id, rinfo, bret))
1538 continue;
1539 }
1540
1541 if (add_id_to_freelist(rinfo, id)) {
1542 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1543 info->gd->disk_name, op_name(bret->operation), id);
1544 continue;
1545 }
1546
1547 if (bret->status == BLKIF_RSP_OKAY)
1548 blkif_req(req)->error = BLK_STS_OK;
1549 else
1550 blkif_req(req)->error = BLK_STS_IOERR;
1551
1552 switch (bret->operation) {
1553 case BLKIF_OP_DISCARD:
1554 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1555 struct request_queue *rq = info->rq;
1556 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1557 info->gd->disk_name, op_name(bret->operation));
1558 blkif_req(req)->error = BLK_STS_NOTSUPP;
1559 info->feature_discard = 0;
1560 info->feature_secdiscard = 0;
1561 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1562 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1563 }
1564 break;
1565 case BLKIF_OP_FLUSH_DISKCACHE:
1566 case BLKIF_OP_WRITE_BARRIER:
1567 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1568 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1569 info->gd->disk_name, op_name(bret->operation));
1570 blkif_req(req)->error = BLK_STS_NOTSUPP;
1571 }
1572 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1573 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1574 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1575 info->gd->disk_name, op_name(bret->operation));
1576 blkif_req(req)->error = BLK_STS_NOTSUPP;
1577 }
1578 if (unlikely(blkif_req(req)->error)) {
1579 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1580 blkif_req(req)->error = BLK_STS_OK;
1581 info->feature_fua = 0;
1582 info->feature_flush = 0;
1583 xlvbd_flush(info);
1584 }
1585 fallthrough;
1586 case BLKIF_OP_READ:
1587 case BLKIF_OP_WRITE:
1588 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1589 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1590 "request: %x\n", bret->status);
1591
1592 break;
1593 default:
1594 BUG();
1595 }
1596
1597 if (likely(!blk_should_fake_timeout(req->q)))
1598 blk_mq_complete_request(req);
1599 }
1600
1601 rinfo->ring.rsp_cons = i;
1602
1603 if (i != rinfo->ring.req_prod_pvt) {
1604 int more_to_do;
1605 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1606 if (more_to_do)
1607 goto again;
1608 } else
1609 rinfo->ring.sring->rsp_event = i + 1;
1610
1611 kick_pending_request_queues_locked(rinfo);
1612
1613 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1614
1615 return IRQ_HANDLED;
1616}
1617
1618
1619static int setup_blkring(struct xenbus_device *dev,
1620 struct blkfront_ring_info *rinfo)
1621{
1622 struct blkif_sring *sring;
1623 int err, i;
1624 struct blkfront_info *info = rinfo->dev_info;
1625 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1626 grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1627
1628 for (i = 0; i < info->nr_ring_pages; i++)
1629 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1630
1631 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1632 get_order(ring_size));
1633 if (!sring) {
1634 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1635 return -ENOMEM;
1636 }
1637 SHARED_RING_INIT(sring);
1638 FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1639
1640 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1641 if (err < 0) {
1642 free_pages((unsigned long)sring, get_order(ring_size));
1643 rinfo->ring.sring = NULL;
1644 goto fail;
1645 }
1646 for (i = 0; i < info->nr_ring_pages; i++)
1647 rinfo->ring_ref[i] = gref[i];
1648
1649 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1650 if (err)
1651 goto fail;
1652
1653 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1654 "blkif", rinfo);
1655 if (err <= 0) {
1656 xenbus_dev_fatal(dev, err,
1657 "bind_evtchn_to_irqhandler failed");
1658 goto fail;
1659 }
1660 rinfo->irq = err;
1661
1662 return 0;
1663fail:
1664 blkif_free(info, 0);
1665 return err;
1666}
1667
1668/*
1669 * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1670 * ring buffer may have multi pages depending on ->nr_ring_pages.
1671 */
1672static int write_per_ring_nodes(struct xenbus_transaction xbt,
1673 struct blkfront_ring_info *rinfo, const char *dir)
1674{
1675 int err;
1676 unsigned int i;
1677 const char *message = NULL;
1678 struct blkfront_info *info = rinfo->dev_info;
1679
1680 if (info->nr_ring_pages == 1) {
1681 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1682 if (err) {
1683 message = "writing ring-ref";
1684 goto abort_transaction;
1685 }
1686 } else {
1687 for (i = 0; i < info->nr_ring_pages; i++) {
1688 char ring_ref_name[RINGREF_NAME_LEN];
1689
1690 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1691 err = xenbus_printf(xbt, dir, ring_ref_name,
1692 "%u", rinfo->ring_ref[i]);
1693 if (err) {
1694 message = "writing ring-ref";
1695 goto abort_transaction;
1696 }
1697 }
1698 }
1699
1700 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1701 if (err) {
1702 message = "writing event-channel";
1703 goto abort_transaction;
1704 }
1705
1706 return 0;
1707
1708abort_transaction:
1709 xenbus_transaction_end(xbt, 1);
1710 if (message)
1711 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1712
1713 return err;
1714}
1715
1716/* Common code used when first setting up, and when resuming. */
1717static int talk_to_blkback(struct xenbus_device *dev,
1718 struct blkfront_info *info)
1719{
1720 const char *message = NULL;
1721 struct xenbus_transaction xbt;
1722 int err;
1723 unsigned int i, max_page_order;
1724 unsigned int ring_page_order;
1725 struct blkfront_ring_info *rinfo;
1726
1727 if (!info)
1728 return -ENODEV;
1729
1730 max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1731 "max-ring-page-order", 0);
1732 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1733 info->nr_ring_pages = 1 << ring_page_order;
1734
1735 err = negotiate_mq(info);
1736 if (err)
1737 goto destroy_blkring;
1738
1739 for_each_rinfo(info, rinfo, i) {
1740 /* Create shared ring, alloc event channel. */
1741 err = setup_blkring(dev, rinfo);
1742 if (err)
1743 goto destroy_blkring;
1744 }
1745
1746again:
1747 err = xenbus_transaction_start(&xbt);
1748 if (err) {
1749 xenbus_dev_fatal(dev, err, "starting transaction");
1750 goto destroy_blkring;
1751 }
1752
1753 if (info->nr_ring_pages > 1) {
1754 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1755 ring_page_order);
1756 if (err) {
1757 message = "writing ring-page-order";
1758 goto abort_transaction;
1759 }
1760 }
1761
1762 /* We already got the number of queues/rings in _probe */
1763 if (info->nr_rings == 1) {
1764 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename);
1765 if (err)
1766 goto destroy_blkring;
1767 } else {
1768 char *path;
1769 size_t pathsize;
1770
1771 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1772 info->nr_rings);
1773 if (err) {
1774 message = "writing multi-queue-num-queues";
1775 goto abort_transaction;
1776 }
1777
1778 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1779 path = kmalloc(pathsize, GFP_KERNEL);
1780 if (!path) {
1781 err = -ENOMEM;
1782 message = "ENOMEM while writing ring references";
1783 goto abort_transaction;
1784 }
1785
1786 for_each_rinfo(info, rinfo, i) {
1787 memset(path, 0, pathsize);
1788 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1789 err = write_per_ring_nodes(xbt, rinfo, path);
1790 if (err) {
1791 kfree(path);
1792 goto destroy_blkring;
1793 }
1794 }
1795 kfree(path);
1796 }
1797 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1798 XEN_IO_PROTO_ABI_NATIVE);
1799 if (err) {
1800 message = "writing protocol";
1801 goto abort_transaction;
1802 }
1803 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
1804 info->feature_persistent);
1805 if (err)
1806 dev_warn(&dev->dev,
1807 "writing persistent grants feature to xenbus");
1808
1809 err = xenbus_transaction_end(xbt, 0);
1810 if (err) {
1811 if (err == -EAGAIN)
1812 goto again;
1813 xenbus_dev_fatal(dev, err, "completing transaction");
1814 goto destroy_blkring;
1815 }
1816
1817 for_each_rinfo(info, rinfo, i) {
1818 unsigned int j;
1819
1820 for (j = 0; j < BLK_RING_SIZE(info); j++)
1821 rinfo->shadow[j].req.u.rw.id = j + 1;
1822 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1823 }
1824 xenbus_switch_state(dev, XenbusStateInitialised);
1825
1826 return 0;
1827
1828 abort_transaction:
1829 xenbus_transaction_end(xbt, 1);
1830 if (message)
1831 xenbus_dev_fatal(dev, err, "%s", message);
1832 destroy_blkring:
1833 blkif_free(info, 0);
1834 return err;
1835}
1836
1837static int negotiate_mq(struct blkfront_info *info)
1838{
1839 unsigned int backend_max_queues;
1840 unsigned int i;
1841 struct blkfront_ring_info *rinfo;
1842
1843 BUG_ON(info->nr_rings);
1844
1845 /* Check if backend supports multiple queues. */
1846 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1847 "multi-queue-max-queues", 1);
1848 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1849 /* We need at least one ring. */
1850 if (!info->nr_rings)
1851 info->nr_rings = 1;
1852
1853 info->rinfo_size = struct_size(info->rinfo, shadow,
1854 BLK_RING_SIZE(info));
1855 info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL);
1856 if (!info->rinfo) {
1857 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1858 info->nr_rings = 0;
1859 return -ENOMEM;
1860 }
1861
1862 for_each_rinfo(info, rinfo, i) {
1863 INIT_LIST_HEAD(&rinfo->indirect_pages);
1864 INIT_LIST_HEAD(&rinfo->grants);
1865 rinfo->dev_info = info;
1866 INIT_WORK(&rinfo->work, blkif_restart_queue);
1867 spin_lock_init(&rinfo->ring_lock);
1868 }
1869 return 0;
1870}
1871
1872/* Enable the persistent grants feature. */
1873static bool feature_persistent = true;
1874module_param(feature_persistent, bool, 0644);
1875MODULE_PARM_DESC(feature_persistent,
1876 "Enables the persistent grants feature");
1877
1878/*
1879 * Entry point to this code when a new device is created. Allocate the basic
1880 * structures and the ring buffer for communication with the backend, and
1881 * inform the backend of the appropriate details for those. Switch to
1882 * Initialised state.
1883 */
1884static int blkfront_probe(struct xenbus_device *dev,
1885 const struct xenbus_device_id *id)
1886{
1887 int err, vdevice;
1888 struct blkfront_info *info;
1889
1890 /* FIXME: Use dynamic device id if this is not set. */
1891 err = xenbus_scanf(XBT_NIL, dev->nodename,
1892 "virtual-device", "%i", &vdevice);
1893 if (err != 1) {
1894 /* go looking in the extended area instead */
1895 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1896 "%i", &vdevice);
1897 if (err != 1) {
1898 xenbus_dev_fatal(dev, err, "reading virtual-device");
1899 return err;
1900 }
1901 }
1902
1903 if (xen_hvm_domain()) {
1904 char *type;
1905 int len;
1906 /* no unplug has been done: do not hook devices != xen vbds */
1907 if (xen_has_pv_and_legacy_disk_devices()) {
1908 int major;
1909
1910 if (!VDEV_IS_EXTENDED(vdevice))
1911 major = BLKIF_MAJOR(vdevice);
1912 else
1913 major = XENVBD_MAJOR;
1914
1915 if (major != XENVBD_MAJOR) {
1916 printk(KERN_INFO
1917 "%s: HVM does not support vbd %d as xen block device\n",
1918 __func__, vdevice);
1919 return -ENODEV;
1920 }
1921 }
1922 /* do not create a PV cdrom device if we are an HVM guest */
1923 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1924 if (IS_ERR(type))
1925 return -ENODEV;
1926 if (strncmp(type, "cdrom", 5) == 0) {
1927 kfree(type);
1928 return -ENODEV;
1929 }
1930 kfree(type);
1931 }
1932 info = kzalloc(sizeof(*info), GFP_KERNEL);
1933 if (!info) {
1934 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1935 return -ENOMEM;
1936 }
1937
1938 info->xbdev = dev;
1939
1940 mutex_init(&info->mutex);
1941 info->vdevice = vdevice;
1942 info->connected = BLKIF_STATE_DISCONNECTED;
1943
1944 info->feature_persistent = feature_persistent;
1945
1946 /* Front end dir is a number, which is used as the id. */
1947 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1948 dev_set_drvdata(&dev->dev, info);
1949
1950 mutex_lock(&blkfront_mutex);
1951 list_add(&info->info_list, &info_list);
1952 mutex_unlock(&blkfront_mutex);
1953
1954 return 0;
1955}
1956
1957static int blkif_recover(struct blkfront_info *info)
1958{
1959 unsigned int r_index;
1960 struct request *req, *n;
1961 int rc;
1962 struct bio *bio;
1963 unsigned int segs;
1964 struct blkfront_ring_info *rinfo;
1965
1966 blkfront_gather_backend_features(info);
1967 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
1968 blkif_set_queue_limits(info);
1969 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
1970 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
1971
1972 for_each_rinfo(info, rinfo, r_index) {
1973 rc = blkfront_setup_indirect(rinfo);
1974 if (rc)
1975 return rc;
1976 }
1977 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1978
1979 /* Now safe for us to use the shared ring */
1980 info->connected = BLKIF_STATE_CONNECTED;
1981
1982 for_each_rinfo(info, rinfo, r_index) {
1983 /* Kick any other new requests queued since we resumed */
1984 kick_pending_request_queues(rinfo);
1985 }
1986
1987 list_for_each_entry_safe(req, n, &info->requests, queuelist) {
1988 /* Requeue pending requests (flush or discard) */
1989 list_del_init(&req->queuelist);
1990 BUG_ON(req->nr_phys_segments > segs);
1991 blk_mq_requeue_request(req, false);
1992 }
1993 blk_mq_start_stopped_hw_queues(info->rq, true);
1994 blk_mq_kick_requeue_list(info->rq);
1995
1996 while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
1997 /* Traverse the list of pending bios and re-queue them */
1998 submit_bio(bio);
1999 }
2000
2001 return 0;
2002}
2003
2004/*
2005 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2006 * driver restart. We tear down our blkif structure and recreate it, but
2007 * leave the device-layer structures intact so that this is transparent to the
2008 * rest of the kernel.
2009 */
2010static int blkfront_resume(struct xenbus_device *dev)
2011{
2012 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2013 int err = 0;
2014 unsigned int i, j;
2015 struct blkfront_ring_info *rinfo;
2016
2017 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2018
2019 bio_list_init(&info->bio_list);
2020 INIT_LIST_HEAD(&info->requests);
2021 for_each_rinfo(info, rinfo, i) {
2022 struct bio_list merge_bio;
2023 struct blk_shadow *shadow = rinfo->shadow;
2024
2025 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2026 /* Not in use? */
2027 if (!shadow[j].request)
2028 continue;
2029
2030 /*
2031 * Get the bios in the request so we can re-queue them.
2032 */
2033 if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2034 req_op(shadow[j].request) == REQ_OP_DISCARD ||
2035 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2036 shadow[j].request->cmd_flags & REQ_FUA) {
2037 /*
2038 * Flush operations don't contain bios, so
2039 * we need to requeue the whole request
2040 *
2041 * XXX: but this doesn't make any sense for a
2042 * write with the FUA flag set..
2043 */
2044 list_add(&shadow[j].request->queuelist, &info->requests);
2045 continue;
2046 }
2047 merge_bio.head = shadow[j].request->bio;
2048 merge_bio.tail = shadow[j].request->biotail;
2049 bio_list_merge(&info->bio_list, &merge_bio);
2050 shadow[j].request->bio = NULL;
2051 blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2052 }
2053 }
2054
2055 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2056
2057 err = talk_to_blkback(dev, info);
2058 if (!err)
2059 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2060
2061 /*
2062 * We have to wait for the backend to switch to
2063 * connected state, since we want to read which
2064 * features it supports.
2065 */
2066
2067 return err;
2068}
2069
2070static void blkfront_closing(struct blkfront_info *info)
2071{
2072 struct xenbus_device *xbdev = info->xbdev;
2073 struct blkfront_ring_info *rinfo;
2074 unsigned int i;
2075
2076 if (xbdev->state == XenbusStateClosing)
2077 return;
2078
2079 /* No more blkif_request(). */
2080 blk_mq_stop_hw_queues(info->rq);
2081 blk_set_queue_dying(info->rq);
2082 set_capacity(info->gd, 0);
2083
2084 for_each_rinfo(info, rinfo, i) {
2085 /* No more gnttab callback work. */
2086 gnttab_cancel_free_callback(&rinfo->callback);
2087
2088 /* Flush gnttab callback work. Must be done with no locks held. */
2089 flush_work(&rinfo->work);
2090 }
2091
2092 xenbus_frontend_closed(xbdev);
2093}
2094
2095static void blkfront_setup_discard(struct blkfront_info *info)
2096{
2097 info->feature_discard = 1;
2098 info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
2099 "discard-granularity",
2100 0);
2101 info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
2102 "discard-alignment", 0);
2103 info->feature_secdiscard =
2104 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2105 0);
2106}
2107
2108static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2109{
2110 unsigned int psegs, grants, memflags;
2111 int err, i;
2112 struct blkfront_info *info = rinfo->dev_info;
2113
2114 memflags = memalloc_noio_save();
2115
2116 if (info->max_indirect_segments == 0) {
2117 if (!HAS_EXTRA_REQ)
2118 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2119 else {
2120 /*
2121 * When an extra req is required, the maximum
2122 * grants supported is related to the size of the
2123 * Linux block segment.
2124 */
2125 grants = GRANTS_PER_PSEG;
2126 }
2127 }
2128 else
2129 grants = info->max_indirect_segments;
2130 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2131
2132 err = fill_grant_buffer(rinfo,
2133 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2134 if (err)
2135 goto out_of_memory;
2136
2137 if (!info->feature_persistent && info->max_indirect_segments) {
2138 /*
2139 * We are using indirect descriptors but not persistent
2140 * grants, we need to allocate a set of pages that can be
2141 * used for mapping indirect grefs
2142 */
2143 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2144
2145 BUG_ON(!list_empty(&rinfo->indirect_pages));
2146 for (i = 0; i < num; i++) {
2147 struct page *indirect_page = alloc_page(GFP_KERNEL);
2148 if (!indirect_page)
2149 goto out_of_memory;
2150 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2151 }
2152 }
2153
2154 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2155 rinfo->shadow[i].grants_used =
2156 kvcalloc(grants,
2157 sizeof(rinfo->shadow[i].grants_used[0]),
2158 GFP_KERNEL);
2159 rinfo->shadow[i].sg = kvcalloc(psegs,
2160 sizeof(rinfo->shadow[i].sg[0]),
2161 GFP_KERNEL);
2162 if (info->max_indirect_segments)
2163 rinfo->shadow[i].indirect_grants =
2164 kvcalloc(INDIRECT_GREFS(grants),
2165 sizeof(rinfo->shadow[i].indirect_grants[0]),
2166 GFP_KERNEL);
2167 if ((rinfo->shadow[i].grants_used == NULL) ||
2168 (rinfo->shadow[i].sg == NULL) ||
2169 (info->max_indirect_segments &&
2170 (rinfo->shadow[i].indirect_grants == NULL)))
2171 goto out_of_memory;
2172 sg_init_table(rinfo->shadow[i].sg, psegs);
2173 }
2174
2175 memalloc_noio_restore(memflags);
2176
2177 return 0;
2178
2179out_of_memory:
2180 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2181 kvfree(rinfo->shadow[i].grants_used);
2182 rinfo->shadow[i].grants_used = NULL;
2183 kvfree(rinfo->shadow[i].sg);
2184 rinfo->shadow[i].sg = NULL;
2185 kvfree(rinfo->shadow[i].indirect_grants);
2186 rinfo->shadow[i].indirect_grants = NULL;
2187 }
2188 if (!list_empty(&rinfo->indirect_pages)) {
2189 struct page *indirect_page, *n;
2190 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2191 list_del(&indirect_page->lru);
2192 __free_page(indirect_page);
2193 }
2194 }
2195
2196 memalloc_noio_restore(memflags);
2197
2198 return -ENOMEM;
2199}
2200
2201/*
2202 * Gather all backend feature-*
2203 */
2204static void blkfront_gather_backend_features(struct blkfront_info *info)
2205{
2206 unsigned int indirect_segments;
2207
2208 info->feature_flush = 0;
2209 info->feature_fua = 0;
2210
2211 /*
2212 * If there's no "feature-barrier" defined, then it means
2213 * we're dealing with a very old backend which writes
2214 * synchronously; nothing to do.
2215 *
2216 * If there are barriers, then we use flush.
2217 */
2218 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2219 info->feature_flush = 1;
2220 info->feature_fua = 1;
2221 }
2222
2223 /*
2224 * And if there is "feature-flush-cache" use that above
2225 * barriers.
2226 */
2227 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2228 0)) {
2229 info->feature_flush = 1;
2230 info->feature_fua = 0;
2231 }
2232
2233 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2234 blkfront_setup_discard(info);
2235
2236 if (info->feature_persistent)
2237 info->feature_persistent =
2238 !!xenbus_read_unsigned(info->xbdev->otherend,
2239 "feature-persistent", 0);
2240
2241 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2242 "feature-max-indirect-segments", 0);
2243 if (indirect_segments > xen_blkif_max_segments)
2244 indirect_segments = xen_blkif_max_segments;
2245 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2246 indirect_segments = 0;
2247 info->max_indirect_segments = indirect_segments;
2248
2249 if (info->feature_persistent) {
2250 mutex_lock(&blkfront_mutex);
2251 schedule_delayed_work(&blkfront_work, HZ * 10);
2252 mutex_unlock(&blkfront_mutex);
2253 }
2254}
2255
2256/*
2257 * Invoked when the backend is finally 'ready' (and has told produced
2258 * the details about the physical device - #sectors, size, etc).
2259 */
2260static void blkfront_connect(struct blkfront_info *info)
2261{
2262 unsigned long long sectors;
2263 unsigned long sector_size;
2264 unsigned int physical_sector_size;
2265 unsigned int binfo;
2266 int err, i;
2267 struct blkfront_ring_info *rinfo;
2268
2269 switch (info->connected) {
2270 case BLKIF_STATE_CONNECTED:
2271 /*
2272 * Potentially, the back-end may be signalling
2273 * a capacity change; update the capacity.
2274 */
2275 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2276 "sectors", "%Lu", §ors);
2277 if (XENBUS_EXIST_ERR(err))
2278 return;
2279 printk(KERN_INFO "Setting capacity to %Lu\n",
2280 sectors);
2281 set_capacity_and_notify(info->gd, sectors);
2282
2283 return;
2284 case BLKIF_STATE_SUSPENDED:
2285 /*
2286 * If we are recovering from suspension, we need to wait
2287 * for the backend to announce it's features before
2288 * reconnecting, at least we need to know if the backend
2289 * supports indirect descriptors, and how many.
2290 */
2291 blkif_recover(info);
2292 return;
2293
2294 default:
2295 break;
2296 }
2297
2298 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2299 __func__, info->xbdev->otherend);
2300
2301 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2302 "sectors", "%llu", §ors,
2303 "info", "%u", &binfo,
2304 "sector-size", "%lu", §or_size,
2305 NULL);
2306 if (err) {
2307 xenbus_dev_fatal(info->xbdev, err,
2308 "reading backend fields at %s",
2309 info->xbdev->otherend);
2310 return;
2311 }
2312
2313 /*
2314 * physical-sector-size is a newer field, so old backends may not
2315 * provide this. Assume physical sector size to be the same as
2316 * sector_size in that case.
2317 */
2318 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2319 "physical-sector-size",
2320 sector_size);
2321 blkfront_gather_backend_features(info);
2322 for_each_rinfo(info, rinfo, i) {
2323 err = blkfront_setup_indirect(rinfo);
2324 if (err) {
2325 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2326 info->xbdev->otherend);
2327 blkif_free(info, 0);
2328 break;
2329 }
2330 }
2331
2332 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2333 physical_sector_size);
2334 if (err) {
2335 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2336 info->xbdev->otherend);
2337 goto fail;
2338 }
2339
2340 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2341
2342 /* Kick pending requests. */
2343 info->connected = BLKIF_STATE_CONNECTED;
2344 for_each_rinfo(info, rinfo, i)
2345 kick_pending_request_queues(rinfo);
2346
2347 device_add_disk(&info->xbdev->dev, info->gd, NULL);
2348
2349 info->is_ready = 1;
2350 return;
2351
2352fail:
2353 blkif_free(info, 0);
2354 return;
2355}
2356
2357/*
2358 * Callback received when the backend's state changes.
2359 */
2360static void blkback_changed(struct xenbus_device *dev,
2361 enum xenbus_state backend_state)
2362{
2363 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2364
2365 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2366
2367 switch (backend_state) {
2368 case XenbusStateInitWait:
2369 if (dev->state != XenbusStateInitialising)
2370 break;
2371 if (talk_to_blkback(dev, info))
2372 break;
2373 break;
2374 case XenbusStateInitialising:
2375 case XenbusStateInitialised:
2376 case XenbusStateReconfiguring:
2377 case XenbusStateReconfigured:
2378 case XenbusStateUnknown:
2379 break;
2380
2381 case XenbusStateConnected:
2382 /*
2383 * talk_to_blkback sets state to XenbusStateInitialised
2384 * and blkfront_connect sets it to XenbusStateConnected
2385 * (if connection went OK).
2386 *
2387 * If the backend (or toolstack) decides to poke at backend
2388 * state (and re-trigger the watch by setting the state repeatedly
2389 * to XenbusStateConnected (4)) we need to deal with this.
2390 * This is allowed as this is used to communicate to the guest
2391 * that the size of disk has changed!
2392 */
2393 if ((dev->state != XenbusStateInitialised) &&
2394 (dev->state != XenbusStateConnected)) {
2395 if (talk_to_blkback(dev, info))
2396 break;
2397 }
2398
2399 blkfront_connect(info);
2400 break;
2401
2402 case XenbusStateClosed:
2403 if (dev->state == XenbusStateClosed)
2404 break;
2405 fallthrough;
2406 case XenbusStateClosing:
2407 blkfront_closing(info);
2408 break;
2409 }
2410}
2411
2412static int blkfront_remove(struct xenbus_device *xbdev)
2413{
2414 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2415
2416 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2417
2418 del_gendisk(info->gd);
2419
2420 mutex_lock(&blkfront_mutex);
2421 list_del(&info->info_list);
2422 mutex_unlock(&blkfront_mutex);
2423
2424 blkif_free(info, 0);
2425 xlbd_release_minors(info->gd->first_minor, info->gd->minors);
2426 blk_cleanup_disk(info->gd);
2427 blk_mq_free_tag_set(&info->tag_set);
2428
2429 kfree(info);
2430 return 0;
2431}
2432
2433static int blkfront_is_ready(struct xenbus_device *dev)
2434{
2435 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2436
2437 return info->is_ready && info->xbdev;
2438}
2439
2440static const struct block_device_operations xlvbd_block_fops =
2441{
2442 .owner = THIS_MODULE,
2443 .getgeo = blkif_getgeo,
2444 .ioctl = blkif_ioctl,
2445 .compat_ioctl = blkdev_compat_ptr_ioctl,
2446};
2447
2448
2449static const struct xenbus_device_id blkfront_ids[] = {
2450 { "vbd" },
2451 { "" }
2452};
2453
2454static struct xenbus_driver blkfront_driver = {
2455 .ids = blkfront_ids,
2456 .probe = blkfront_probe,
2457 .remove = blkfront_remove,
2458 .resume = blkfront_resume,
2459 .otherend_changed = blkback_changed,
2460 .is_ready = blkfront_is_ready,
2461};
2462
2463static void purge_persistent_grants(struct blkfront_info *info)
2464{
2465 unsigned int i;
2466 unsigned long flags;
2467 struct blkfront_ring_info *rinfo;
2468
2469 for_each_rinfo(info, rinfo, i) {
2470 struct grant *gnt_list_entry, *tmp;
2471
2472 spin_lock_irqsave(&rinfo->ring_lock, flags);
2473
2474 if (rinfo->persistent_gnts_c == 0) {
2475 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2476 continue;
2477 }
2478
2479 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2480 node) {
2481 if (gnt_list_entry->gref == GRANT_INVALID_REF ||
2482 gnttab_query_foreign_access(gnt_list_entry->gref))
2483 continue;
2484
2485 list_del(&gnt_list_entry->node);
2486 gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
2487 rinfo->persistent_gnts_c--;
2488 gnt_list_entry->gref = GRANT_INVALID_REF;
2489 list_add_tail(&gnt_list_entry->node, &rinfo->grants);
2490 }
2491
2492 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2493 }
2494}
2495
2496static void blkfront_delay_work(struct work_struct *work)
2497{
2498 struct blkfront_info *info;
2499 bool need_schedule_work = false;
2500
2501 mutex_lock(&blkfront_mutex);
2502
2503 list_for_each_entry(info, &info_list, info_list) {
2504 if (info->feature_persistent) {
2505 need_schedule_work = true;
2506 mutex_lock(&info->mutex);
2507 purge_persistent_grants(info);
2508 mutex_unlock(&info->mutex);
2509 }
2510 }
2511
2512 if (need_schedule_work)
2513 schedule_delayed_work(&blkfront_work, HZ * 10);
2514
2515 mutex_unlock(&blkfront_mutex);
2516}
2517
2518static int __init xlblk_init(void)
2519{
2520 int ret;
2521 int nr_cpus = num_online_cpus();
2522
2523 if (!xen_domain())
2524 return -ENODEV;
2525
2526 if (!xen_has_pv_disk_devices())
2527 return -ENODEV;
2528
2529 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2530 pr_warn("xen_blk: can't get major %d with name %s\n",
2531 XENVBD_MAJOR, DEV_NAME);
2532 return -ENODEV;
2533 }
2534
2535 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2536 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2537
2538 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2539 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2540 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2541 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2542 }
2543
2544 if (xen_blkif_max_queues > nr_cpus) {
2545 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2546 xen_blkif_max_queues, nr_cpus);
2547 xen_blkif_max_queues = nr_cpus;
2548 }
2549
2550 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2551
2552 ret = xenbus_register_frontend(&blkfront_driver);
2553 if (ret) {
2554 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2555 return ret;
2556 }
2557
2558 return 0;
2559}
2560module_init(xlblk_init);
2561
2562
2563static void __exit xlblk_exit(void)
2564{
2565 cancel_delayed_work_sync(&blkfront_work);
2566
2567 xenbus_unregister_driver(&blkfront_driver);
2568 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2569 kfree(minors);
2570}
2571module_exit(xlblk_exit);
2572
2573MODULE_DESCRIPTION("Xen virtual block device frontend");
2574MODULE_LICENSE("GPL");
2575MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2576MODULE_ALIAS("xen:vbd");
2577MODULE_ALIAS("xenblk");