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