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1/*
2 * blkfront.c
3 *
4 * XenLinux virtual block device driver.
5 *
6 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
7 * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
8 * Copyright (c) 2004, Christian Limpach
9 * Copyright (c) 2004, Andrew Warfield
10 * Copyright (c) 2005, Christopher Clark
11 * Copyright (c) 2005, XenSource Ltd
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License version 2
15 * as published by the Free Software Foundation; or, when distributed
16 * separately from the Linux kernel or incorporated into other
17 * software packages, subject to the following license:
18 *
19 * Permission is hereby granted, free of charge, to any person obtaining a copy
20 * of this source file (the "Software"), to deal in the Software without
21 * restriction, including without limitation the rights to use, copy, modify,
22 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
23 * and to permit persons to whom the Software is furnished to do so, subject to
24 * the following conditions:
25 *
26 * The above copyright notice and this permission notice shall be included in
27 * all copies or substantial portions of the Software.
28 *
29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
35 * IN THE SOFTWARE.
36 */
37
38#include <linux/interrupt.h>
39#include <linux/blkdev.h>
40#include <linux/hdreg.h>
41#include <linux/cdrom.h>
42#include <linux/module.h>
43#include <linux/slab.h>
44#include <linux/mutex.h>
45#include <linux/scatterlist.h>
46
47#include <xen/xen.h>
48#include <xen/xenbus.h>
49#include <xen/grant_table.h>
50#include <xen/events.h>
51#include <xen/page.h>
52#include <xen/platform_pci.h>
53
54#include <xen/interface/grant_table.h>
55#include <xen/interface/io/blkif.h>
56#include <xen/interface/io/protocols.h>
57
58#include <asm/xen/hypervisor.h>
59
60enum blkif_state {
61 BLKIF_STATE_DISCONNECTED,
62 BLKIF_STATE_CONNECTED,
63 BLKIF_STATE_SUSPENDED,
64};
65
66struct blk_shadow {
67 struct blkif_request req;
68 struct request *request;
69 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
70};
71
72static DEFINE_MUTEX(blkfront_mutex);
73static const struct block_device_operations xlvbd_block_fops;
74
75#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
76
77/*
78 * We have one of these per vbd, whether ide, scsi or 'other'. They
79 * hang in private_data off the gendisk structure. We may end up
80 * putting all kinds of interesting stuff here :-)
81 */
82struct blkfront_info
83{
84 struct mutex mutex;
85 struct xenbus_device *xbdev;
86 struct gendisk *gd;
87 int vdevice;
88 blkif_vdev_t handle;
89 enum blkif_state connected;
90 int ring_ref;
91 struct blkif_front_ring ring;
92 struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
93 unsigned int evtchn, irq;
94 struct request_queue *rq;
95 struct work_struct work;
96 struct gnttab_free_callback callback;
97 struct blk_shadow shadow[BLK_RING_SIZE];
98 unsigned long shadow_free;
99 unsigned int feature_flush;
100 unsigned int flush_op;
101 int is_ready;
102};
103
104static DEFINE_SPINLOCK(blkif_io_lock);
105
106static unsigned int nr_minors;
107static unsigned long *minors;
108static DEFINE_SPINLOCK(minor_lock);
109
110#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
111 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
112#define GRANT_INVALID_REF 0
113
114#define PARTS_PER_DISK 16
115#define PARTS_PER_EXT_DISK 256
116
117#define BLKIF_MAJOR(dev) ((dev)>>8)
118#define BLKIF_MINOR(dev) ((dev) & 0xff)
119
120#define EXT_SHIFT 28
121#define EXTENDED (1<<EXT_SHIFT)
122#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
123#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
124#define EMULATED_HD_DISK_MINOR_OFFSET (0)
125#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
126#define EMULATED_SD_DISK_MINOR_OFFSET (0)
127#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
128
129#define DEV_NAME "xvd" /* name in /dev */
130
131static int get_id_from_freelist(struct blkfront_info *info)
132{
133 unsigned long free = info->shadow_free;
134 BUG_ON(free >= BLK_RING_SIZE);
135 info->shadow_free = info->shadow[free].req.id;
136 info->shadow[free].req.id = 0x0fffffee; /* debug */
137 return free;
138}
139
140static void add_id_to_freelist(struct blkfront_info *info,
141 unsigned long id)
142{
143 info->shadow[id].req.id = info->shadow_free;
144 info->shadow[id].request = NULL;
145 info->shadow_free = id;
146}
147
148static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
149{
150 unsigned int end = minor + nr;
151 int rc;
152
153 if (end > nr_minors) {
154 unsigned long *bitmap, *old;
155
156 bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
157 GFP_KERNEL);
158 if (bitmap == NULL)
159 return -ENOMEM;
160
161 spin_lock(&minor_lock);
162 if (end > nr_minors) {
163 old = minors;
164 memcpy(bitmap, minors,
165 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
166 minors = bitmap;
167 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
168 } else
169 old = bitmap;
170 spin_unlock(&minor_lock);
171 kfree(old);
172 }
173
174 spin_lock(&minor_lock);
175 if (find_next_bit(minors, end, minor) >= end) {
176 for (; minor < end; ++minor)
177 __set_bit(minor, minors);
178 rc = 0;
179 } else
180 rc = -EBUSY;
181 spin_unlock(&minor_lock);
182
183 return rc;
184}
185
186static void xlbd_release_minors(unsigned int minor, unsigned int nr)
187{
188 unsigned int end = minor + nr;
189
190 BUG_ON(end > nr_minors);
191 spin_lock(&minor_lock);
192 for (; minor < end; ++minor)
193 __clear_bit(minor, minors);
194 spin_unlock(&minor_lock);
195}
196
197static void blkif_restart_queue_callback(void *arg)
198{
199 struct blkfront_info *info = (struct blkfront_info *)arg;
200 schedule_work(&info->work);
201}
202
203static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
204{
205 /* We don't have real geometry info, but let's at least return
206 values consistent with the size of the device */
207 sector_t nsect = get_capacity(bd->bd_disk);
208 sector_t cylinders = nsect;
209
210 hg->heads = 0xff;
211 hg->sectors = 0x3f;
212 sector_div(cylinders, hg->heads * hg->sectors);
213 hg->cylinders = cylinders;
214 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
215 hg->cylinders = 0xffff;
216 return 0;
217}
218
219static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
220 unsigned command, unsigned long argument)
221{
222 struct blkfront_info *info = bdev->bd_disk->private_data;
223 int i;
224
225 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
226 command, (long)argument);
227
228 switch (command) {
229 case CDROMMULTISESSION:
230 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
231 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
232 if (put_user(0, (char __user *)(argument + i)))
233 return -EFAULT;
234 return 0;
235
236 case CDROM_GET_CAPABILITY: {
237 struct gendisk *gd = info->gd;
238 if (gd->flags & GENHD_FL_CD)
239 return 0;
240 return -EINVAL;
241 }
242
243 default:
244 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
245 command);*/
246 return -EINVAL; /* same return as native Linux */
247 }
248
249 return 0;
250}
251
252/*
253 * Generate a Xen blkfront IO request from a blk layer request. Reads
254 * and writes are handled as expected.
255 *
256 * @req: a request struct
257 */
258static int blkif_queue_request(struct request *req)
259{
260 struct blkfront_info *info = req->rq_disk->private_data;
261 unsigned long buffer_mfn;
262 struct blkif_request *ring_req;
263 unsigned long id;
264 unsigned int fsect, lsect;
265 int i, ref;
266 grant_ref_t gref_head;
267 struct scatterlist *sg;
268
269 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
270 return 1;
271
272 if (gnttab_alloc_grant_references(
273 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
274 gnttab_request_free_callback(
275 &info->callback,
276 blkif_restart_queue_callback,
277 info,
278 BLKIF_MAX_SEGMENTS_PER_REQUEST);
279 return 1;
280 }
281
282 /* Fill out a communications ring structure. */
283 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
284 id = get_id_from_freelist(info);
285 info->shadow[id].request = req;
286
287 ring_req->id = id;
288 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
289 ring_req->handle = info->handle;
290
291 ring_req->operation = rq_data_dir(req) ?
292 BLKIF_OP_WRITE : BLKIF_OP_READ;
293
294 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
295 /*
296 * Ideally we can do an unordered flush-to-disk. In case the
297 * backend onlysupports barriers, use that. A barrier request
298 * a superset of FUA, so we can implement it the same
299 * way. (It's also a FLUSH+FUA, since it is
300 * guaranteed ordered WRT previous writes.)
301 */
302 ring_req->operation = info->flush_op;
303 }
304
305 ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
306 BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
307
308 for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
309 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
310 fsect = sg->offset >> 9;
311 lsect = fsect + (sg->length >> 9) - 1;
312 /* install a grant reference. */
313 ref = gnttab_claim_grant_reference(&gref_head);
314 BUG_ON(ref == -ENOSPC);
315
316 gnttab_grant_foreign_access_ref(
317 ref,
318 info->xbdev->otherend_id,
319 buffer_mfn,
320 rq_data_dir(req) );
321
322 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
323 ring_req->u.rw.seg[i] =
324 (struct blkif_request_segment) {
325 .gref = ref,
326 .first_sect = fsect,
327 .last_sect = lsect };
328 }
329
330 info->ring.req_prod_pvt++;
331
332 /* Keep a private copy so we can reissue requests when recovering. */
333 info->shadow[id].req = *ring_req;
334
335 gnttab_free_grant_references(gref_head);
336
337 return 0;
338}
339
340
341static inline void flush_requests(struct blkfront_info *info)
342{
343 int notify;
344
345 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
346
347 if (notify)
348 notify_remote_via_irq(info->irq);
349}
350
351/*
352 * do_blkif_request
353 * read a block; request is in a request queue
354 */
355static void do_blkif_request(struct request_queue *rq)
356{
357 struct blkfront_info *info = NULL;
358 struct request *req;
359 int queued;
360
361 pr_debug("Entered do_blkif_request\n");
362
363 queued = 0;
364
365 while ((req = blk_peek_request(rq)) != NULL) {
366 info = req->rq_disk->private_data;
367
368 if (RING_FULL(&info->ring))
369 goto wait;
370
371 blk_start_request(req);
372
373 if (req->cmd_type != REQ_TYPE_FS) {
374 __blk_end_request_all(req, -EIO);
375 continue;
376 }
377
378 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
379 "(%u/%u) buffer:%p [%s]\n",
380 req, req->cmd, (unsigned long)blk_rq_pos(req),
381 blk_rq_cur_sectors(req), blk_rq_sectors(req),
382 req->buffer, rq_data_dir(req) ? "write" : "read");
383
384 if (blkif_queue_request(req)) {
385 blk_requeue_request(rq, req);
386wait:
387 /* Avoid pointless unplugs. */
388 blk_stop_queue(rq);
389 break;
390 }
391
392 queued++;
393 }
394
395 if (queued != 0)
396 flush_requests(info);
397}
398
399static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
400{
401 struct request_queue *rq;
402
403 rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
404 if (rq == NULL)
405 return -1;
406
407 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
408
409 /* Hard sector size and max sectors impersonate the equiv. hardware. */
410 blk_queue_logical_block_size(rq, sector_size);
411 blk_queue_max_hw_sectors(rq, 512);
412
413 /* Each segment in a request is up to an aligned page in size. */
414 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
415 blk_queue_max_segment_size(rq, PAGE_SIZE);
416
417 /* Ensure a merged request will fit in a single I/O ring slot. */
418 blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
419
420 /* Make sure buffer addresses are sector-aligned. */
421 blk_queue_dma_alignment(rq, 511);
422
423 /* Make sure we don't use bounce buffers. */
424 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
425
426 gd->queue = rq;
427
428 return 0;
429}
430
431
432static void xlvbd_flush(struct blkfront_info *info)
433{
434 blk_queue_flush(info->rq, info->feature_flush);
435 printk(KERN_INFO "blkfront: %s: %s: %s\n",
436 info->gd->disk_name,
437 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
438 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
439 "flush diskcache" : "barrier or flush"),
440 info->feature_flush ? "enabled" : "disabled");
441}
442
443static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
444{
445 int major;
446 major = BLKIF_MAJOR(vdevice);
447 *minor = BLKIF_MINOR(vdevice);
448 switch (major) {
449 case XEN_IDE0_MAJOR:
450 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
451 *minor = ((*minor / 64) * PARTS_PER_DISK) +
452 EMULATED_HD_DISK_MINOR_OFFSET;
453 break;
454 case XEN_IDE1_MAJOR:
455 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
456 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
457 EMULATED_HD_DISK_MINOR_OFFSET;
458 break;
459 case XEN_SCSI_DISK0_MAJOR:
460 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
461 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
462 break;
463 case XEN_SCSI_DISK1_MAJOR:
464 case XEN_SCSI_DISK2_MAJOR:
465 case XEN_SCSI_DISK3_MAJOR:
466 case XEN_SCSI_DISK4_MAJOR:
467 case XEN_SCSI_DISK5_MAJOR:
468 case XEN_SCSI_DISK6_MAJOR:
469 case XEN_SCSI_DISK7_MAJOR:
470 *offset = (*minor / PARTS_PER_DISK) +
471 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
472 EMULATED_SD_DISK_NAME_OFFSET;
473 *minor = *minor +
474 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
475 EMULATED_SD_DISK_MINOR_OFFSET;
476 break;
477 case XEN_SCSI_DISK8_MAJOR:
478 case XEN_SCSI_DISK9_MAJOR:
479 case XEN_SCSI_DISK10_MAJOR:
480 case XEN_SCSI_DISK11_MAJOR:
481 case XEN_SCSI_DISK12_MAJOR:
482 case XEN_SCSI_DISK13_MAJOR:
483 case XEN_SCSI_DISK14_MAJOR:
484 case XEN_SCSI_DISK15_MAJOR:
485 *offset = (*minor / PARTS_PER_DISK) +
486 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
487 EMULATED_SD_DISK_NAME_OFFSET;
488 *minor = *minor +
489 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
490 EMULATED_SD_DISK_MINOR_OFFSET;
491 break;
492 case XENVBD_MAJOR:
493 *offset = *minor / PARTS_PER_DISK;
494 break;
495 default:
496 printk(KERN_WARNING "blkfront: your disk configuration is "
497 "incorrect, please use an xvd device instead\n");
498 return -ENODEV;
499 }
500 return 0;
501}
502
503static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
504 struct blkfront_info *info,
505 u16 vdisk_info, u16 sector_size)
506{
507 struct gendisk *gd;
508 int nr_minors = 1;
509 int err;
510 unsigned int offset;
511 int minor;
512 int nr_parts;
513
514 BUG_ON(info->gd != NULL);
515 BUG_ON(info->rq != NULL);
516
517 if ((info->vdevice>>EXT_SHIFT) > 1) {
518 /* this is above the extended range; something is wrong */
519 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
520 return -ENODEV;
521 }
522
523 if (!VDEV_IS_EXTENDED(info->vdevice)) {
524 err = xen_translate_vdev(info->vdevice, &minor, &offset);
525 if (err)
526 return err;
527 nr_parts = PARTS_PER_DISK;
528 } else {
529 minor = BLKIF_MINOR_EXT(info->vdevice);
530 nr_parts = PARTS_PER_EXT_DISK;
531 offset = minor / nr_parts;
532 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
533 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
534 "emulated IDE disks,\n\t choose an xvd device name"
535 "from xvde on\n", info->vdevice);
536 }
537 err = -ENODEV;
538
539 if ((minor % nr_parts) == 0)
540 nr_minors = nr_parts;
541
542 err = xlbd_reserve_minors(minor, nr_minors);
543 if (err)
544 goto out;
545 err = -ENODEV;
546
547 gd = alloc_disk(nr_minors);
548 if (gd == NULL)
549 goto release;
550
551 if (nr_minors > 1) {
552 if (offset < 26)
553 sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
554 else
555 sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
556 'a' + ((offset / 26)-1), 'a' + (offset % 26));
557 } else {
558 if (offset < 26)
559 sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
560 'a' + offset,
561 minor & (nr_parts - 1));
562 else
563 sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
564 'a' + ((offset / 26) - 1),
565 'a' + (offset % 26),
566 minor & (nr_parts - 1));
567 }
568
569 gd->major = XENVBD_MAJOR;
570 gd->first_minor = minor;
571 gd->fops = &xlvbd_block_fops;
572 gd->private_data = info;
573 gd->driverfs_dev = &(info->xbdev->dev);
574 set_capacity(gd, capacity);
575
576 if (xlvbd_init_blk_queue(gd, sector_size)) {
577 del_gendisk(gd);
578 goto release;
579 }
580
581 info->rq = gd->queue;
582 info->gd = gd;
583
584 xlvbd_flush(info);
585
586 if (vdisk_info & VDISK_READONLY)
587 set_disk_ro(gd, 1);
588
589 if (vdisk_info & VDISK_REMOVABLE)
590 gd->flags |= GENHD_FL_REMOVABLE;
591
592 if (vdisk_info & VDISK_CDROM)
593 gd->flags |= GENHD_FL_CD;
594
595 return 0;
596
597 release:
598 xlbd_release_minors(minor, nr_minors);
599 out:
600 return err;
601}
602
603static void xlvbd_release_gendisk(struct blkfront_info *info)
604{
605 unsigned int minor, nr_minors;
606 unsigned long flags;
607
608 if (info->rq == NULL)
609 return;
610
611 spin_lock_irqsave(&blkif_io_lock, flags);
612
613 /* No more blkif_request(). */
614 blk_stop_queue(info->rq);
615
616 /* No more gnttab callback work. */
617 gnttab_cancel_free_callback(&info->callback);
618 spin_unlock_irqrestore(&blkif_io_lock, flags);
619
620 /* Flush gnttab callback work. Must be done with no locks held. */
621 flush_work_sync(&info->work);
622
623 del_gendisk(info->gd);
624
625 minor = info->gd->first_minor;
626 nr_minors = info->gd->minors;
627 xlbd_release_minors(minor, nr_minors);
628
629 blk_cleanup_queue(info->rq);
630 info->rq = NULL;
631
632 put_disk(info->gd);
633 info->gd = NULL;
634}
635
636static void kick_pending_request_queues(struct blkfront_info *info)
637{
638 if (!RING_FULL(&info->ring)) {
639 /* Re-enable calldowns. */
640 blk_start_queue(info->rq);
641 /* Kick things off immediately. */
642 do_blkif_request(info->rq);
643 }
644}
645
646static void blkif_restart_queue(struct work_struct *work)
647{
648 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
649
650 spin_lock_irq(&blkif_io_lock);
651 if (info->connected == BLKIF_STATE_CONNECTED)
652 kick_pending_request_queues(info);
653 spin_unlock_irq(&blkif_io_lock);
654}
655
656static void blkif_free(struct blkfront_info *info, int suspend)
657{
658 /* Prevent new requests being issued until we fix things up. */
659 spin_lock_irq(&blkif_io_lock);
660 info->connected = suspend ?
661 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
662 /* No more blkif_request(). */
663 if (info->rq)
664 blk_stop_queue(info->rq);
665 /* No more gnttab callback work. */
666 gnttab_cancel_free_callback(&info->callback);
667 spin_unlock_irq(&blkif_io_lock);
668
669 /* Flush gnttab callback work. Must be done with no locks held. */
670 flush_work_sync(&info->work);
671
672 /* Free resources associated with old device channel. */
673 if (info->ring_ref != GRANT_INVALID_REF) {
674 gnttab_end_foreign_access(info->ring_ref, 0,
675 (unsigned long)info->ring.sring);
676 info->ring_ref = GRANT_INVALID_REF;
677 info->ring.sring = NULL;
678 }
679 if (info->irq)
680 unbind_from_irqhandler(info->irq, info);
681 info->evtchn = info->irq = 0;
682
683}
684
685static void blkif_completion(struct blk_shadow *s)
686{
687 int i;
688 for (i = 0; i < s->req.nr_segments; i++)
689 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
690}
691
692static irqreturn_t blkif_interrupt(int irq, void *dev_id)
693{
694 struct request *req;
695 struct blkif_response *bret;
696 RING_IDX i, rp;
697 unsigned long flags;
698 struct blkfront_info *info = (struct blkfront_info *)dev_id;
699 int error;
700
701 spin_lock_irqsave(&blkif_io_lock, flags);
702
703 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
704 spin_unlock_irqrestore(&blkif_io_lock, flags);
705 return IRQ_HANDLED;
706 }
707
708 again:
709 rp = info->ring.sring->rsp_prod;
710 rmb(); /* Ensure we see queued responses up to 'rp'. */
711
712 for (i = info->ring.rsp_cons; i != rp; i++) {
713 unsigned long id;
714
715 bret = RING_GET_RESPONSE(&info->ring, i);
716 id = bret->id;
717 req = info->shadow[id].request;
718
719 blkif_completion(&info->shadow[id]);
720
721 add_id_to_freelist(info, id);
722
723 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
724 switch (bret->operation) {
725 case BLKIF_OP_FLUSH_DISKCACHE:
726 case BLKIF_OP_WRITE_BARRIER:
727 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
728 printk(KERN_WARNING "blkfront: %s: write %s op failed\n",
729 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
730 "barrier" : "flush disk cache",
731 info->gd->disk_name);
732 error = -EOPNOTSUPP;
733 }
734 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
735 info->shadow[id].req.nr_segments == 0)) {
736 printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
737 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
738 "barrier" : "flush disk cache",
739 info->gd->disk_name);
740 error = -EOPNOTSUPP;
741 }
742 if (unlikely(error)) {
743 if (error == -EOPNOTSUPP)
744 error = 0;
745 info->feature_flush = 0;
746 info->flush_op = 0;
747 xlvbd_flush(info);
748 }
749 /* fall through */
750 case BLKIF_OP_READ:
751 case BLKIF_OP_WRITE:
752 if (unlikely(bret->status != BLKIF_RSP_OKAY))
753 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
754 "request: %x\n", bret->status);
755
756 __blk_end_request_all(req, error);
757 break;
758 default:
759 BUG();
760 }
761 }
762
763 info->ring.rsp_cons = i;
764
765 if (i != info->ring.req_prod_pvt) {
766 int more_to_do;
767 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
768 if (more_to_do)
769 goto again;
770 } else
771 info->ring.sring->rsp_event = i + 1;
772
773 kick_pending_request_queues(info);
774
775 spin_unlock_irqrestore(&blkif_io_lock, flags);
776
777 return IRQ_HANDLED;
778}
779
780
781static int setup_blkring(struct xenbus_device *dev,
782 struct blkfront_info *info)
783{
784 struct blkif_sring *sring;
785 int err;
786
787 info->ring_ref = GRANT_INVALID_REF;
788
789 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
790 if (!sring) {
791 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
792 return -ENOMEM;
793 }
794 SHARED_RING_INIT(sring);
795 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
796
797 sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
798
799 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
800 if (err < 0) {
801 free_page((unsigned long)sring);
802 info->ring.sring = NULL;
803 goto fail;
804 }
805 info->ring_ref = err;
806
807 err = xenbus_alloc_evtchn(dev, &info->evtchn);
808 if (err)
809 goto fail;
810
811 err = bind_evtchn_to_irqhandler(info->evtchn,
812 blkif_interrupt,
813 IRQF_SAMPLE_RANDOM, "blkif", info);
814 if (err <= 0) {
815 xenbus_dev_fatal(dev, err,
816 "bind_evtchn_to_irqhandler failed");
817 goto fail;
818 }
819 info->irq = err;
820
821 return 0;
822fail:
823 blkif_free(info, 0);
824 return err;
825}
826
827
828/* Common code used when first setting up, and when resuming. */
829static int talk_to_blkback(struct xenbus_device *dev,
830 struct blkfront_info *info)
831{
832 const char *message = NULL;
833 struct xenbus_transaction xbt;
834 int err;
835
836 /* Create shared ring, alloc event channel. */
837 err = setup_blkring(dev, info);
838 if (err)
839 goto out;
840
841again:
842 err = xenbus_transaction_start(&xbt);
843 if (err) {
844 xenbus_dev_fatal(dev, err, "starting transaction");
845 goto destroy_blkring;
846 }
847
848 err = xenbus_printf(xbt, dev->nodename,
849 "ring-ref", "%u", info->ring_ref);
850 if (err) {
851 message = "writing ring-ref";
852 goto abort_transaction;
853 }
854 err = xenbus_printf(xbt, dev->nodename,
855 "event-channel", "%u", info->evtchn);
856 if (err) {
857 message = "writing event-channel";
858 goto abort_transaction;
859 }
860 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
861 XEN_IO_PROTO_ABI_NATIVE);
862 if (err) {
863 message = "writing protocol";
864 goto abort_transaction;
865 }
866
867 err = xenbus_transaction_end(xbt, 0);
868 if (err) {
869 if (err == -EAGAIN)
870 goto again;
871 xenbus_dev_fatal(dev, err, "completing transaction");
872 goto destroy_blkring;
873 }
874
875 xenbus_switch_state(dev, XenbusStateInitialised);
876
877 return 0;
878
879 abort_transaction:
880 xenbus_transaction_end(xbt, 1);
881 if (message)
882 xenbus_dev_fatal(dev, err, "%s", message);
883 destroy_blkring:
884 blkif_free(info, 0);
885 out:
886 return err;
887}
888
889/**
890 * Entry point to this code when a new device is created. Allocate the basic
891 * structures and the ring buffer for communication with the backend, and
892 * inform the backend of the appropriate details for those. Switch to
893 * Initialised state.
894 */
895static int blkfront_probe(struct xenbus_device *dev,
896 const struct xenbus_device_id *id)
897{
898 int err, vdevice, i;
899 struct blkfront_info *info;
900
901 /* FIXME: Use dynamic device id if this is not set. */
902 err = xenbus_scanf(XBT_NIL, dev->nodename,
903 "virtual-device", "%i", &vdevice);
904 if (err != 1) {
905 /* go looking in the extended area instead */
906 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
907 "%i", &vdevice);
908 if (err != 1) {
909 xenbus_dev_fatal(dev, err, "reading virtual-device");
910 return err;
911 }
912 }
913
914 if (xen_hvm_domain()) {
915 char *type;
916 int len;
917 /* no unplug has been done: do not hook devices != xen vbds */
918 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
919 int major;
920
921 if (!VDEV_IS_EXTENDED(vdevice))
922 major = BLKIF_MAJOR(vdevice);
923 else
924 major = XENVBD_MAJOR;
925
926 if (major != XENVBD_MAJOR) {
927 printk(KERN_INFO
928 "%s: HVM does not support vbd %d as xen block device\n",
929 __FUNCTION__, vdevice);
930 return -ENODEV;
931 }
932 }
933 /* do not create a PV cdrom device if we are an HVM guest */
934 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
935 if (IS_ERR(type))
936 return -ENODEV;
937 if (strncmp(type, "cdrom", 5) == 0) {
938 kfree(type);
939 return -ENODEV;
940 }
941 kfree(type);
942 }
943 info = kzalloc(sizeof(*info), GFP_KERNEL);
944 if (!info) {
945 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
946 return -ENOMEM;
947 }
948
949 mutex_init(&info->mutex);
950 info->xbdev = dev;
951 info->vdevice = vdevice;
952 info->connected = BLKIF_STATE_DISCONNECTED;
953 INIT_WORK(&info->work, blkif_restart_queue);
954
955 for (i = 0; i < BLK_RING_SIZE; i++)
956 info->shadow[i].req.id = i+1;
957 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
958
959 /* Front end dir is a number, which is used as the id. */
960 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
961 dev_set_drvdata(&dev->dev, info);
962
963 err = talk_to_blkback(dev, info);
964 if (err) {
965 kfree(info);
966 dev_set_drvdata(&dev->dev, NULL);
967 return err;
968 }
969
970 return 0;
971}
972
973
974static int blkif_recover(struct blkfront_info *info)
975{
976 int i;
977 struct blkif_request *req;
978 struct blk_shadow *copy;
979 int j;
980
981 /* Stage 1: Make a safe copy of the shadow state. */
982 copy = kmalloc(sizeof(info->shadow),
983 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
984 if (!copy)
985 return -ENOMEM;
986 memcpy(copy, info->shadow, sizeof(info->shadow));
987
988 /* Stage 2: Set up free list. */
989 memset(&info->shadow, 0, sizeof(info->shadow));
990 for (i = 0; i < BLK_RING_SIZE; i++)
991 info->shadow[i].req.id = i+1;
992 info->shadow_free = info->ring.req_prod_pvt;
993 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
994
995 /* Stage 3: Find pending requests and requeue them. */
996 for (i = 0; i < BLK_RING_SIZE; i++) {
997 /* Not in use? */
998 if (!copy[i].request)
999 continue;
1000
1001 /* Grab a request slot and copy shadow state into it. */
1002 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
1003 *req = copy[i].req;
1004
1005 /* We get a new request id, and must reset the shadow state. */
1006 req->id = get_id_from_freelist(info);
1007 memcpy(&info->shadow[req->id], ©[i], sizeof(copy[i]));
1008
1009 /* Rewrite any grant references invalidated by susp/resume. */
1010 for (j = 0; j < req->nr_segments; j++)
1011 gnttab_grant_foreign_access_ref(
1012 req->u.rw.seg[j].gref,
1013 info->xbdev->otherend_id,
1014 pfn_to_mfn(info->shadow[req->id].frame[j]),
1015 rq_data_dir(info->shadow[req->id].request));
1016 info->shadow[req->id].req = *req;
1017
1018 info->ring.req_prod_pvt++;
1019 }
1020
1021 kfree(copy);
1022
1023 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1024
1025 spin_lock_irq(&blkif_io_lock);
1026
1027 /* Now safe for us to use the shared ring */
1028 info->connected = BLKIF_STATE_CONNECTED;
1029
1030 /* Send off requeued requests */
1031 flush_requests(info);
1032
1033 /* Kick any other new requests queued since we resumed */
1034 kick_pending_request_queues(info);
1035
1036 spin_unlock_irq(&blkif_io_lock);
1037
1038 return 0;
1039}
1040
1041/**
1042 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1043 * driver restart. We tear down our blkif structure and recreate it, but
1044 * leave the device-layer structures intact so that this is transparent to the
1045 * rest of the kernel.
1046 */
1047static int blkfront_resume(struct xenbus_device *dev)
1048{
1049 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1050 int err;
1051
1052 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1053
1054 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1055
1056 err = talk_to_blkback(dev, info);
1057 if (info->connected == BLKIF_STATE_SUSPENDED && !err)
1058 err = blkif_recover(info);
1059
1060 return err;
1061}
1062
1063static void
1064blkfront_closing(struct blkfront_info *info)
1065{
1066 struct xenbus_device *xbdev = info->xbdev;
1067 struct block_device *bdev = NULL;
1068
1069 mutex_lock(&info->mutex);
1070
1071 if (xbdev->state == XenbusStateClosing) {
1072 mutex_unlock(&info->mutex);
1073 return;
1074 }
1075
1076 if (info->gd)
1077 bdev = bdget_disk(info->gd, 0);
1078
1079 mutex_unlock(&info->mutex);
1080
1081 if (!bdev) {
1082 xenbus_frontend_closed(xbdev);
1083 return;
1084 }
1085
1086 mutex_lock(&bdev->bd_mutex);
1087
1088 if (bdev->bd_openers) {
1089 xenbus_dev_error(xbdev, -EBUSY,
1090 "Device in use; refusing to close");
1091 xenbus_switch_state(xbdev, XenbusStateClosing);
1092 } else {
1093 xlvbd_release_gendisk(info);
1094 xenbus_frontend_closed(xbdev);
1095 }
1096
1097 mutex_unlock(&bdev->bd_mutex);
1098 bdput(bdev);
1099}
1100
1101/*
1102 * Invoked when the backend is finally 'ready' (and has told produced
1103 * the details about the physical device - #sectors, size, etc).
1104 */
1105static void blkfront_connect(struct blkfront_info *info)
1106{
1107 unsigned long long sectors;
1108 unsigned long sector_size;
1109 unsigned int binfo;
1110 int err;
1111 int barrier, flush;
1112
1113 switch (info->connected) {
1114 case BLKIF_STATE_CONNECTED:
1115 /*
1116 * Potentially, the back-end may be signalling
1117 * a capacity change; update the capacity.
1118 */
1119 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1120 "sectors", "%Lu", §ors);
1121 if (XENBUS_EXIST_ERR(err))
1122 return;
1123 printk(KERN_INFO "Setting capacity to %Lu\n",
1124 sectors);
1125 set_capacity(info->gd, sectors);
1126 revalidate_disk(info->gd);
1127
1128 /* fall through */
1129 case BLKIF_STATE_SUSPENDED:
1130 return;
1131
1132 default:
1133 break;
1134 }
1135
1136 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1137 __func__, info->xbdev->otherend);
1138
1139 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1140 "sectors", "%llu", §ors,
1141 "info", "%u", &binfo,
1142 "sector-size", "%lu", §or_size,
1143 NULL);
1144 if (err) {
1145 xenbus_dev_fatal(info->xbdev, err,
1146 "reading backend fields at %s",
1147 info->xbdev->otherend);
1148 return;
1149 }
1150
1151 info->feature_flush = 0;
1152 info->flush_op = 0;
1153
1154 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1155 "feature-barrier", "%d", &barrier,
1156 NULL);
1157
1158 /*
1159 * If there's no "feature-barrier" defined, then it means
1160 * we're dealing with a very old backend which writes
1161 * synchronously; nothing to do.
1162 *
1163 * If there are barriers, then we use flush.
1164 */
1165 if (!err && barrier) {
1166 info->feature_flush = REQ_FLUSH | REQ_FUA;
1167 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1168 }
1169 /*
1170 * And if there is "feature-flush-cache" use that above
1171 * barriers.
1172 */
1173 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1174 "feature-flush-cache", "%d", &flush,
1175 NULL);
1176
1177 if (!err && flush) {
1178 info->feature_flush = REQ_FLUSH;
1179 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1180 }
1181
1182 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1183 if (err) {
1184 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1185 info->xbdev->otherend);
1186 return;
1187 }
1188
1189 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1190
1191 /* Kick pending requests. */
1192 spin_lock_irq(&blkif_io_lock);
1193 info->connected = BLKIF_STATE_CONNECTED;
1194 kick_pending_request_queues(info);
1195 spin_unlock_irq(&blkif_io_lock);
1196
1197 add_disk(info->gd);
1198
1199 info->is_ready = 1;
1200}
1201
1202/**
1203 * Callback received when the backend's state changes.
1204 */
1205static void blkback_changed(struct xenbus_device *dev,
1206 enum xenbus_state backend_state)
1207{
1208 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1209
1210 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1211
1212 switch (backend_state) {
1213 case XenbusStateInitialising:
1214 case XenbusStateInitWait:
1215 case XenbusStateInitialised:
1216 case XenbusStateReconfiguring:
1217 case XenbusStateReconfigured:
1218 case XenbusStateUnknown:
1219 case XenbusStateClosed:
1220 break;
1221
1222 case XenbusStateConnected:
1223 blkfront_connect(info);
1224 break;
1225
1226 case XenbusStateClosing:
1227 blkfront_closing(info);
1228 break;
1229 }
1230}
1231
1232static int blkfront_remove(struct xenbus_device *xbdev)
1233{
1234 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1235 struct block_device *bdev = NULL;
1236 struct gendisk *disk;
1237
1238 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1239
1240 blkif_free(info, 0);
1241
1242 mutex_lock(&info->mutex);
1243
1244 disk = info->gd;
1245 if (disk)
1246 bdev = bdget_disk(disk, 0);
1247
1248 info->xbdev = NULL;
1249 mutex_unlock(&info->mutex);
1250
1251 if (!bdev) {
1252 kfree(info);
1253 return 0;
1254 }
1255
1256 /*
1257 * The xbdev was removed before we reached the Closed
1258 * state. See if it's safe to remove the disk. If the bdev
1259 * isn't closed yet, we let release take care of it.
1260 */
1261
1262 mutex_lock(&bdev->bd_mutex);
1263 info = disk->private_data;
1264
1265 dev_warn(disk_to_dev(disk),
1266 "%s was hot-unplugged, %d stale handles\n",
1267 xbdev->nodename, bdev->bd_openers);
1268
1269 if (info && !bdev->bd_openers) {
1270 xlvbd_release_gendisk(info);
1271 disk->private_data = NULL;
1272 kfree(info);
1273 }
1274
1275 mutex_unlock(&bdev->bd_mutex);
1276 bdput(bdev);
1277
1278 return 0;
1279}
1280
1281static int blkfront_is_ready(struct xenbus_device *dev)
1282{
1283 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1284
1285 return info->is_ready && info->xbdev;
1286}
1287
1288static int blkif_open(struct block_device *bdev, fmode_t mode)
1289{
1290 struct gendisk *disk = bdev->bd_disk;
1291 struct blkfront_info *info;
1292 int err = 0;
1293
1294 mutex_lock(&blkfront_mutex);
1295
1296 info = disk->private_data;
1297 if (!info) {
1298 /* xbdev gone */
1299 err = -ERESTARTSYS;
1300 goto out;
1301 }
1302
1303 mutex_lock(&info->mutex);
1304
1305 if (!info->gd)
1306 /* xbdev is closed */
1307 err = -ERESTARTSYS;
1308
1309 mutex_unlock(&info->mutex);
1310
1311out:
1312 mutex_unlock(&blkfront_mutex);
1313 return err;
1314}
1315
1316static int blkif_release(struct gendisk *disk, fmode_t mode)
1317{
1318 struct blkfront_info *info = disk->private_data;
1319 struct block_device *bdev;
1320 struct xenbus_device *xbdev;
1321
1322 mutex_lock(&blkfront_mutex);
1323
1324 bdev = bdget_disk(disk, 0);
1325 bdput(bdev);
1326
1327 if (bdev->bd_openers)
1328 goto out;
1329
1330 /*
1331 * Check if we have been instructed to close. We will have
1332 * deferred this request, because the bdev was still open.
1333 */
1334
1335 mutex_lock(&info->mutex);
1336 xbdev = info->xbdev;
1337
1338 if (xbdev && xbdev->state == XenbusStateClosing) {
1339 /* pending switch to state closed */
1340 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1341 xlvbd_release_gendisk(info);
1342 xenbus_frontend_closed(info->xbdev);
1343 }
1344
1345 mutex_unlock(&info->mutex);
1346
1347 if (!xbdev) {
1348 /* sudden device removal */
1349 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1350 xlvbd_release_gendisk(info);
1351 disk->private_data = NULL;
1352 kfree(info);
1353 }
1354
1355out:
1356 mutex_unlock(&blkfront_mutex);
1357 return 0;
1358}
1359
1360static const struct block_device_operations xlvbd_block_fops =
1361{
1362 .owner = THIS_MODULE,
1363 .open = blkif_open,
1364 .release = blkif_release,
1365 .getgeo = blkif_getgeo,
1366 .ioctl = blkif_ioctl,
1367};
1368
1369
1370static const struct xenbus_device_id blkfront_ids[] = {
1371 { "vbd" },
1372 { "" }
1373};
1374
1375static struct xenbus_driver blkfront = {
1376 .name = "vbd",
1377 .owner = THIS_MODULE,
1378 .ids = blkfront_ids,
1379 .probe = blkfront_probe,
1380 .remove = blkfront_remove,
1381 .resume = blkfront_resume,
1382 .otherend_changed = blkback_changed,
1383 .is_ready = blkfront_is_ready,
1384};
1385
1386static int __init xlblk_init(void)
1387{
1388 if (!xen_domain())
1389 return -ENODEV;
1390
1391 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1392 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1393 XENVBD_MAJOR, DEV_NAME);
1394 return -ENODEV;
1395 }
1396
1397 return xenbus_register_frontend(&blkfront);
1398}
1399module_init(xlblk_init);
1400
1401
1402static void __exit xlblk_exit(void)
1403{
1404 return xenbus_unregister_driver(&blkfront);
1405}
1406module_exit(xlblk_exit);
1407
1408MODULE_DESCRIPTION("Xen virtual block device frontend");
1409MODULE_LICENSE("GPL");
1410MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1411MODULE_ALIAS("xen:vbd");
1412MODULE_ALIAS("xenblk");
1/*
2 * blkfront.c
3 *
4 * XenLinux virtual block device driver.
5 *
6 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
7 * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
8 * Copyright (c) 2004, Christian Limpach
9 * Copyright (c) 2004, Andrew Warfield
10 * Copyright (c) 2005, Christopher Clark
11 * Copyright (c) 2005, XenSource Ltd
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License version 2
15 * as published by the Free Software Foundation; or, when distributed
16 * separately from the Linux kernel or incorporated into other
17 * software packages, subject to the following license:
18 *
19 * Permission is hereby granted, free of charge, to any person obtaining a copy
20 * of this source file (the "Software"), to deal in the Software without
21 * restriction, including without limitation the rights to use, copy, modify,
22 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
23 * and to permit persons to whom the Software is furnished to do so, subject to
24 * the following conditions:
25 *
26 * The above copyright notice and this permission notice shall be included in
27 * all copies or substantial portions of the Software.
28 *
29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
35 * IN THE SOFTWARE.
36 */
37
38#include <linux/interrupt.h>
39#include <linux/blkdev.h>
40#include <linux/blk-mq.h>
41#include <linux/hdreg.h>
42#include <linux/cdrom.h>
43#include <linux/module.h>
44#include <linux/slab.h>
45#include <linux/mutex.h>
46#include <linux/scatterlist.h>
47#include <linux/bitmap.h>
48#include <linux/list.h>
49#include <linux/workqueue.h>
50
51#include <xen/xen.h>
52#include <xen/xenbus.h>
53#include <xen/grant_table.h>
54#include <xen/events.h>
55#include <xen/page.h>
56#include <xen/platform_pci.h>
57
58#include <xen/interface/grant_table.h>
59#include <xen/interface/io/blkif.h>
60#include <xen/interface/io/protocols.h>
61
62#include <asm/xen/hypervisor.h>
63
64/*
65 * The minimal size of segment supported by the block framework is PAGE_SIZE.
66 * When Linux is using a different page size than Xen, it may not be possible
67 * to put all the data in a single segment.
68 * This can happen when the backend doesn't support indirect descriptor and
69 * therefore the maximum amount of data that a request can carry is
70 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
71 *
72 * Note that we only support one extra request. So the Linux page size
73 * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
74 * 88KB.
75 */
76#define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
77
78enum blkif_state {
79 BLKIF_STATE_DISCONNECTED,
80 BLKIF_STATE_CONNECTED,
81 BLKIF_STATE_SUSPENDED,
82};
83
84struct grant {
85 grant_ref_t gref;
86 struct page *page;
87 struct list_head node;
88};
89
90enum blk_req_status {
91 REQ_WAITING,
92 REQ_DONE,
93 REQ_ERROR,
94 REQ_EOPNOTSUPP,
95};
96
97struct blk_shadow {
98 struct blkif_request req;
99 struct request *request;
100 struct grant **grants_used;
101 struct grant **indirect_grants;
102 struct scatterlist *sg;
103 unsigned int num_sg;
104 enum blk_req_status status;
105
106 #define NO_ASSOCIATED_ID ~0UL
107 /*
108 * Id of the sibling if we ever need 2 requests when handling a
109 * block I/O request
110 */
111 unsigned long associated_id;
112};
113
114struct blkif_req {
115 blk_status_t error;
116};
117
118static inline struct blkif_req *blkif_req(struct request *rq)
119{
120 return blk_mq_rq_to_pdu(rq);
121}
122
123static DEFINE_MUTEX(blkfront_mutex);
124static const struct block_device_operations xlvbd_block_fops;
125static struct delayed_work blkfront_work;
126static LIST_HEAD(info_list);
127
128/*
129 * Maximum number of segments in indirect requests, the actual value used by
130 * the frontend driver is the minimum of this value and the value provided
131 * by the backend driver.
132 */
133
134static unsigned int xen_blkif_max_segments = 32;
135module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
136MODULE_PARM_DESC(max_indirect_segments,
137 "Maximum amount of segments in indirect requests (default is 32)");
138
139static unsigned int xen_blkif_max_queues = 4;
140module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
141MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
142
143/*
144 * Maximum order of pages to be used for the shared ring between front and
145 * backend, 4KB page granularity is used.
146 */
147static unsigned int xen_blkif_max_ring_order;
148module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
149MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
150
151#define BLK_RING_SIZE(info) \
152 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
153
154#define BLK_MAX_RING_SIZE \
155 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
156
157/*
158 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
159 * characters are enough. Define to 20 to keep consistent with backend.
160 */
161#define RINGREF_NAME_LEN (20)
162/*
163 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
164 */
165#define QUEUE_NAME_LEN (17)
166
167/*
168 * Per-ring info.
169 * Every blkfront device can associate with one or more blkfront_ring_info,
170 * depending on how many hardware queues/rings to be used.
171 */
172struct blkfront_ring_info {
173 /* Lock to protect data in every ring buffer. */
174 spinlock_t ring_lock;
175 struct blkif_front_ring ring;
176 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
177 unsigned int evtchn, irq;
178 struct work_struct work;
179 struct gnttab_free_callback callback;
180 struct blk_shadow shadow[BLK_MAX_RING_SIZE];
181 struct list_head indirect_pages;
182 struct list_head grants;
183 unsigned int persistent_gnts_c;
184 unsigned long shadow_free;
185 struct blkfront_info *dev_info;
186};
187
188/*
189 * We have one of these per vbd, whether ide, scsi or 'other'. They
190 * hang in private_data off the gendisk structure. We may end up
191 * putting all kinds of interesting stuff here :-)
192 */
193struct blkfront_info
194{
195 struct mutex mutex;
196 struct xenbus_device *xbdev;
197 struct gendisk *gd;
198 u16 sector_size;
199 unsigned int physical_sector_size;
200 int vdevice;
201 blkif_vdev_t handle;
202 enum blkif_state connected;
203 /* Number of pages per ring buffer. */
204 unsigned int nr_ring_pages;
205 struct request_queue *rq;
206 unsigned int feature_flush:1;
207 unsigned int feature_fua:1;
208 unsigned int feature_discard:1;
209 unsigned int feature_secdiscard:1;
210 unsigned int feature_persistent:1;
211 unsigned int discard_granularity;
212 unsigned int discard_alignment;
213 /* Number of 4KB segments handled */
214 unsigned int max_indirect_segments;
215 int is_ready;
216 struct blk_mq_tag_set tag_set;
217 struct blkfront_ring_info *rinfo;
218 unsigned int nr_rings;
219 /* Save uncomplete reqs and bios for migration. */
220 struct list_head requests;
221 struct bio_list bio_list;
222 struct list_head info_list;
223};
224
225static unsigned int nr_minors;
226static unsigned long *minors;
227static DEFINE_SPINLOCK(minor_lock);
228
229#define GRANT_INVALID_REF 0
230
231#define PARTS_PER_DISK 16
232#define PARTS_PER_EXT_DISK 256
233
234#define BLKIF_MAJOR(dev) ((dev)>>8)
235#define BLKIF_MINOR(dev) ((dev) & 0xff)
236
237#define EXT_SHIFT 28
238#define EXTENDED (1<<EXT_SHIFT)
239#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
240#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
241#define EMULATED_HD_DISK_MINOR_OFFSET (0)
242#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
243#define EMULATED_SD_DISK_MINOR_OFFSET (0)
244#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
245
246#define DEV_NAME "xvd" /* name in /dev */
247
248/*
249 * Grants are always the same size as a Xen page (i.e 4KB).
250 * A physical segment is always the same size as a Linux page.
251 * Number of grants per physical segment
252 */
253#define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
254
255#define GRANTS_PER_INDIRECT_FRAME \
256 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
257
258#define INDIRECT_GREFS(_grants) \
259 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
260
261static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
262static void blkfront_gather_backend_features(struct blkfront_info *info);
263static int negotiate_mq(struct blkfront_info *info);
264
265static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
266{
267 unsigned long free = rinfo->shadow_free;
268
269 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
270 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
271 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
272 return free;
273}
274
275static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
276 unsigned long id)
277{
278 if (rinfo->shadow[id].req.u.rw.id != id)
279 return -EINVAL;
280 if (rinfo->shadow[id].request == NULL)
281 return -EINVAL;
282 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
283 rinfo->shadow[id].request = NULL;
284 rinfo->shadow_free = id;
285 return 0;
286}
287
288static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
289{
290 struct blkfront_info *info = rinfo->dev_info;
291 struct page *granted_page;
292 struct grant *gnt_list_entry, *n;
293 int i = 0;
294
295 while (i < num) {
296 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
297 if (!gnt_list_entry)
298 goto out_of_memory;
299
300 if (info->feature_persistent) {
301 granted_page = alloc_page(GFP_NOIO);
302 if (!granted_page) {
303 kfree(gnt_list_entry);
304 goto out_of_memory;
305 }
306 gnt_list_entry->page = granted_page;
307 }
308
309 gnt_list_entry->gref = GRANT_INVALID_REF;
310 list_add(&gnt_list_entry->node, &rinfo->grants);
311 i++;
312 }
313
314 return 0;
315
316out_of_memory:
317 list_for_each_entry_safe(gnt_list_entry, n,
318 &rinfo->grants, node) {
319 list_del(&gnt_list_entry->node);
320 if (info->feature_persistent)
321 __free_page(gnt_list_entry->page);
322 kfree(gnt_list_entry);
323 i--;
324 }
325 BUG_ON(i != 0);
326 return -ENOMEM;
327}
328
329static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
330{
331 struct grant *gnt_list_entry;
332
333 BUG_ON(list_empty(&rinfo->grants));
334 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
335 node);
336 list_del(&gnt_list_entry->node);
337
338 if (gnt_list_entry->gref != GRANT_INVALID_REF)
339 rinfo->persistent_gnts_c--;
340
341 return gnt_list_entry;
342}
343
344static inline void grant_foreign_access(const struct grant *gnt_list_entry,
345 const struct blkfront_info *info)
346{
347 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
348 info->xbdev->otherend_id,
349 gnt_list_entry->page,
350 0);
351}
352
353static struct grant *get_grant(grant_ref_t *gref_head,
354 unsigned long gfn,
355 struct blkfront_ring_info *rinfo)
356{
357 struct grant *gnt_list_entry = get_free_grant(rinfo);
358 struct blkfront_info *info = rinfo->dev_info;
359
360 if (gnt_list_entry->gref != GRANT_INVALID_REF)
361 return gnt_list_entry;
362
363 /* Assign a gref to this page */
364 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
365 BUG_ON(gnt_list_entry->gref == -ENOSPC);
366 if (info->feature_persistent)
367 grant_foreign_access(gnt_list_entry, info);
368 else {
369 /* Grant access to the GFN passed by the caller */
370 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
371 info->xbdev->otherend_id,
372 gfn, 0);
373 }
374
375 return gnt_list_entry;
376}
377
378static struct grant *get_indirect_grant(grant_ref_t *gref_head,
379 struct blkfront_ring_info *rinfo)
380{
381 struct grant *gnt_list_entry = get_free_grant(rinfo);
382 struct blkfront_info *info = rinfo->dev_info;
383
384 if (gnt_list_entry->gref != GRANT_INVALID_REF)
385 return gnt_list_entry;
386
387 /* Assign a gref to this page */
388 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
389 BUG_ON(gnt_list_entry->gref == -ENOSPC);
390 if (!info->feature_persistent) {
391 struct page *indirect_page;
392
393 /* Fetch a pre-allocated page to use for indirect grefs */
394 BUG_ON(list_empty(&rinfo->indirect_pages));
395 indirect_page = list_first_entry(&rinfo->indirect_pages,
396 struct page, lru);
397 list_del(&indirect_page->lru);
398 gnt_list_entry->page = indirect_page;
399 }
400 grant_foreign_access(gnt_list_entry, info);
401
402 return gnt_list_entry;
403}
404
405static const char *op_name(int op)
406{
407 static const char *const names[] = {
408 [BLKIF_OP_READ] = "read",
409 [BLKIF_OP_WRITE] = "write",
410 [BLKIF_OP_WRITE_BARRIER] = "barrier",
411 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
412 [BLKIF_OP_DISCARD] = "discard" };
413
414 if (op < 0 || op >= ARRAY_SIZE(names))
415 return "unknown";
416
417 if (!names[op])
418 return "reserved";
419
420 return names[op];
421}
422static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
423{
424 unsigned int end = minor + nr;
425 int rc;
426
427 if (end > nr_minors) {
428 unsigned long *bitmap, *old;
429
430 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
431 GFP_KERNEL);
432 if (bitmap == NULL)
433 return -ENOMEM;
434
435 spin_lock(&minor_lock);
436 if (end > nr_minors) {
437 old = minors;
438 memcpy(bitmap, minors,
439 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
440 minors = bitmap;
441 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
442 } else
443 old = bitmap;
444 spin_unlock(&minor_lock);
445 kfree(old);
446 }
447
448 spin_lock(&minor_lock);
449 if (find_next_bit(minors, end, minor) >= end) {
450 bitmap_set(minors, minor, nr);
451 rc = 0;
452 } else
453 rc = -EBUSY;
454 spin_unlock(&minor_lock);
455
456 return rc;
457}
458
459static void xlbd_release_minors(unsigned int minor, unsigned int nr)
460{
461 unsigned int end = minor + nr;
462
463 BUG_ON(end > nr_minors);
464 spin_lock(&minor_lock);
465 bitmap_clear(minors, minor, nr);
466 spin_unlock(&minor_lock);
467}
468
469static void blkif_restart_queue_callback(void *arg)
470{
471 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
472 schedule_work(&rinfo->work);
473}
474
475static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
476{
477 /* We don't have real geometry info, but let's at least return
478 values consistent with the size of the device */
479 sector_t nsect = get_capacity(bd->bd_disk);
480 sector_t cylinders = nsect;
481
482 hg->heads = 0xff;
483 hg->sectors = 0x3f;
484 sector_div(cylinders, hg->heads * hg->sectors);
485 hg->cylinders = cylinders;
486 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
487 hg->cylinders = 0xffff;
488 return 0;
489}
490
491static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
492 unsigned command, unsigned long argument)
493{
494 struct blkfront_info *info = bdev->bd_disk->private_data;
495 int i;
496
497 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
498 command, (long)argument);
499
500 switch (command) {
501 case CDROMMULTISESSION:
502 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
503 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
504 if (put_user(0, (char __user *)(argument + i)))
505 return -EFAULT;
506 return 0;
507
508 case CDROM_GET_CAPABILITY: {
509 struct gendisk *gd = info->gd;
510 if (gd->flags & GENHD_FL_CD)
511 return 0;
512 return -EINVAL;
513 }
514
515 default:
516 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
517 command);*/
518 return -EINVAL; /* same return as native Linux */
519 }
520
521 return 0;
522}
523
524static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
525 struct request *req,
526 struct blkif_request **ring_req)
527{
528 unsigned long id;
529
530 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
531 rinfo->ring.req_prod_pvt++;
532
533 id = get_id_from_freelist(rinfo);
534 rinfo->shadow[id].request = req;
535 rinfo->shadow[id].status = REQ_WAITING;
536 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
537
538 (*ring_req)->u.rw.id = id;
539
540 return id;
541}
542
543static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
544{
545 struct blkfront_info *info = rinfo->dev_info;
546 struct blkif_request *ring_req;
547 unsigned long id;
548
549 /* Fill out a communications ring structure. */
550 id = blkif_ring_get_request(rinfo, req, &ring_req);
551
552 ring_req->operation = BLKIF_OP_DISCARD;
553 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
554 ring_req->u.discard.id = id;
555 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
556 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
557 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
558 else
559 ring_req->u.discard.flag = 0;
560
561 /* Keep a private copy so we can reissue requests when recovering. */
562 rinfo->shadow[id].req = *ring_req;
563
564 return 0;
565}
566
567struct setup_rw_req {
568 unsigned int grant_idx;
569 struct blkif_request_segment *segments;
570 struct blkfront_ring_info *rinfo;
571 struct blkif_request *ring_req;
572 grant_ref_t gref_head;
573 unsigned int id;
574 /* Only used when persistent grant is used and it's a read request */
575 bool need_copy;
576 unsigned int bvec_off;
577 char *bvec_data;
578
579 bool require_extra_req;
580 struct blkif_request *extra_ring_req;
581};
582
583static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
584 unsigned int len, void *data)
585{
586 struct setup_rw_req *setup = data;
587 int n, ref;
588 struct grant *gnt_list_entry;
589 unsigned int fsect, lsect;
590 /* Convenient aliases */
591 unsigned int grant_idx = setup->grant_idx;
592 struct blkif_request *ring_req = setup->ring_req;
593 struct blkfront_ring_info *rinfo = setup->rinfo;
594 /*
595 * We always use the shadow of the first request to store the list
596 * of grant associated to the block I/O request. This made the
597 * completion more easy to handle even if the block I/O request is
598 * split.
599 */
600 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
601
602 if (unlikely(setup->require_extra_req &&
603 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
604 /*
605 * We are using the second request, setup grant_idx
606 * to be the index of the segment array.
607 */
608 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
609 ring_req = setup->extra_ring_req;
610 }
611
612 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
613 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
614 if (setup->segments)
615 kunmap_atomic(setup->segments);
616
617 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
618 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
619 shadow->indirect_grants[n] = gnt_list_entry;
620 setup->segments = kmap_atomic(gnt_list_entry->page);
621 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
622 }
623
624 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
625 ref = gnt_list_entry->gref;
626 /*
627 * All the grants are stored in the shadow of the first
628 * request. Therefore we have to use the global index.
629 */
630 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
631
632 if (setup->need_copy) {
633 void *shared_data;
634
635 shared_data = kmap_atomic(gnt_list_entry->page);
636 /*
637 * this does not wipe data stored outside the
638 * range sg->offset..sg->offset+sg->length.
639 * Therefore, blkback *could* see data from
640 * previous requests. This is OK as long as
641 * persistent grants are shared with just one
642 * domain. It may need refactoring if this
643 * changes
644 */
645 memcpy(shared_data + offset,
646 setup->bvec_data + setup->bvec_off,
647 len);
648
649 kunmap_atomic(shared_data);
650 setup->bvec_off += len;
651 }
652
653 fsect = offset >> 9;
654 lsect = fsect + (len >> 9) - 1;
655 if (ring_req->operation != BLKIF_OP_INDIRECT) {
656 ring_req->u.rw.seg[grant_idx] =
657 (struct blkif_request_segment) {
658 .gref = ref,
659 .first_sect = fsect,
660 .last_sect = lsect };
661 } else {
662 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
663 (struct blkif_request_segment) {
664 .gref = ref,
665 .first_sect = fsect,
666 .last_sect = lsect };
667 }
668
669 (setup->grant_idx)++;
670}
671
672static void blkif_setup_extra_req(struct blkif_request *first,
673 struct blkif_request *second)
674{
675 uint16_t nr_segments = first->u.rw.nr_segments;
676
677 /*
678 * The second request is only present when the first request uses
679 * all its segments. It's always the continuity of the first one.
680 */
681 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
682
683 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
684 second->u.rw.sector_number = first->u.rw.sector_number +
685 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
686
687 second->u.rw.handle = first->u.rw.handle;
688 second->operation = first->operation;
689}
690
691static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
692{
693 struct blkfront_info *info = rinfo->dev_info;
694 struct blkif_request *ring_req, *extra_ring_req = NULL;
695 unsigned long id, extra_id = NO_ASSOCIATED_ID;
696 bool require_extra_req = false;
697 int i;
698 struct setup_rw_req setup = {
699 .grant_idx = 0,
700 .segments = NULL,
701 .rinfo = rinfo,
702 .need_copy = rq_data_dir(req) && info->feature_persistent,
703 };
704
705 /*
706 * Used to store if we are able to queue the request by just using
707 * existing persistent grants, or if we have to get new grants,
708 * as there are not sufficiently many free.
709 */
710 bool new_persistent_gnts = false;
711 struct scatterlist *sg;
712 int num_sg, max_grefs, num_grant;
713
714 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
715 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
716 /*
717 * If we are using indirect segments we need to account
718 * for the indirect grefs used in the request.
719 */
720 max_grefs += INDIRECT_GREFS(max_grefs);
721
722 /* Check if we have enough persistent grants to allocate a requests */
723 if (rinfo->persistent_gnts_c < max_grefs) {
724 new_persistent_gnts = true;
725
726 if (gnttab_alloc_grant_references(
727 max_grefs - rinfo->persistent_gnts_c,
728 &setup.gref_head) < 0) {
729 gnttab_request_free_callback(
730 &rinfo->callback,
731 blkif_restart_queue_callback,
732 rinfo,
733 max_grefs - rinfo->persistent_gnts_c);
734 return 1;
735 }
736 }
737
738 /* Fill out a communications ring structure. */
739 id = blkif_ring_get_request(rinfo, req, &ring_req);
740
741 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
742 num_grant = 0;
743 /* Calculate the number of grant used */
744 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
745 num_grant += gnttab_count_grant(sg->offset, sg->length);
746
747 require_extra_req = info->max_indirect_segments == 0 &&
748 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
749 BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
750
751 rinfo->shadow[id].num_sg = num_sg;
752 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
753 likely(!require_extra_req)) {
754 /*
755 * The indirect operation can only be a BLKIF_OP_READ or
756 * BLKIF_OP_WRITE
757 */
758 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
759 ring_req->operation = BLKIF_OP_INDIRECT;
760 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
761 BLKIF_OP_WRITE : BLKIF_OP_READ;
762 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
763 ring_req->u.indirect.handle = info->handle;
764 ring_req->u.indirect.nr_segments = num_grant;
765 } else {
766 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
767 ring_req->u.rw.handle = info->handle;
768 ring_req->operation = rq_data_dir(req) ?
769 BLKIF_OP_WRITE : BLKIF_OP_READ;
770 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
771 /*
772 * Ideally we can do an unordered flush-to-disk.
773 * In case the backend onlysupports barriers, use that.
774 * A barrier request a superset of FUA, so we can
775 * implement it the same way. (It's also a FLUSH+FUA,
776 * since it is guaranteed ordered WRT previous writes.)
777 */
778 if (info->feature_flush && info->feature_fua)
779 ring_req->operation =
780 BLKIF_OP_WRITE_BARRIER;
781 else if (info->feature_flush)
782 ring_req->operation =
783 BLKIF_OP_FLUSH_DISKCACHE;
784 else
785 ring_req->operation = 0;
786 }
787 ring_req->u.rw.nr_segments = num_grant;
788 if (unlikely(require_extra_req)) {
789 extra_id = blkif_ring_get_request(rinfo, req,
790 &extra_ring_req);
791 /*
792 * Only the first request contains the scatter-gather
793 * list.
794 */
795 rinfo->shadow[extra_id].num_sg = 0;
796
797 blkif_setup_extra_req(ring_req, extra_ring_req);
798
799 /* Link the 2 requests together */
800 rinfo->shadow[extra_id].associated_id = id;
801 rinfo->shadow[id].associated_id = extra_id;
802 }
803 }
804
805 setup.ring_req = ring_req;
806 setup.id = id;
807
808 setup.require_extra_req = require_extra_req;
809 if (unlikely(require_extra_req))
810 setup.extra_ring_req = extra_ring_req;
811
812 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
813 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
814
815 if (setup.need_copy) {
816 setup.bvec_off = sg->offset;
817 setup.bvec_data = kmap_atomic(sg_page(sg));
818 }
819
820 gnttab_foreach_grant_in_range(sg_page(sg),
821 sg->offset,
822 sg->length,
823 blkif_setup_rw_req_grant,
824 &setup);
825
826 if (setup.need_copy)
827 kunmap_atomic(setup.bvec_data);
828 }
829 if (setup.segments)
830 kunmap_atomic(setup.segments);
831
832 /* Keep a private copy so we can reissue requests when recovering. */
833 rinfo->shadow[id].req = *ring_req;
834 if (unlikely(require_extra_req))
835 rinfo->shadow[extra_id].req = *extra_ring_req;
836
837 if (new_persistent_gnts)
838 gnttab_free_grant_references(setup.gref_head);
839
840 return 0;
841}
842
843/*
844 * Generate a Xen blkfront IO request from a blk layer request. Reads
845 * and writes are handled as expected.
846 *
847 * @req: a request struct
848 */
849static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
850{
851 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
852 return 1;
853
854 if (unlikely(req_op(req) == REQ_OP_DISCARD ||
855 req_op(req) == REQ_OP_SECURE_ERASE))
856 return blkif_queue_discard_req(req, rinfo);
857 else
858 return blkif_queue_rw_req(req, rinfo);
859}
860
861static inline void flush_requests(struct blkfront_ring_info *rinfo)
862{
863 int notify;
864
865 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
866
867 if (notify)
868 notify_remote_via_irq(rinfo->irq);
869}
870
871static inline bool blkif_request_flush_invalid(struct request *req,
872 struct blkfront_info *info)
873{
874 return (blk_rq_is_passthrough(req) ||
875 ((req_op(req) == REQ_OP_FLUSH) &&
876 !info->feature_flush) ||
877 ((req->cmd_flags & REQ_FUA) &&
878 !info->feature_fua));
879}
880
881static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
882 const struct blk_mq_queue_data *qd)
883{
884 unsigned long flags;
885 int qid = hctx->queue_num;
886 struct blkfront_info *info = hctx->queue->queuedata;
887 struct blkfront_ring_info *rinfo = NULL;
888
889 BUG_ON(info->nr_rings <= qid);
890 rinfo = &info->rinfo[qid];
891 blk_mq_start_request(qd->rq);
892 spin_lock_irqsave(&rinfo->ring_lock, flags);
893 if (RING_FULL(&rinfo->ring))
894 goto out_busy;
895
896 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
897 goto out_err;
898
899 if (blkif_queue_request(qd->rq, rinfo))
900 goto out_busy;
901
902 flush_requests(rinfo);
903 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
904 return BLK_STS_OK;
905
906out_err:
907 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
908 return BLK_STS_IOERR;
909
910out_busy:
911 blk_mq_stop_hw_queue(hctx);
912 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
913 return BLK_STS_DEV_RESOURCE;
914}
915
916static void blkif_complete_rq(struct request *rq)
917{
918 blk_mq_end_request(rq, blkif_req(rq)->error);
919}
920
921static const struct blk_mq_ops blkfront_mq_ops = {
922 .queue_rq = blkif_queue_rq,
923 .complete = blkif_complete_rq,
924};
925
926static void blkif_set_queue_limits(struct blkfront_info *info)
927{
928 struct request_queue *rq = info->rq;
929 struct gendisk *gd = info->gd;
930 unsigned int segments = info->max_indirect_segments ? :
931 BLKIF_MAX_SEGMENTS_PER_REQUEST;
932
933 blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
934
935 if (info->feature_discard) {
936 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
937 blk_queue_max_discard_sectors(rq, get_capacity(gd));
938 rq->limits.discard_granularity = info->discard_granularity;
939 rq->limits.discard_alignment = info->discard_alignment;
940 if (info->feature_secdiscard)
941 blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
942 }
943
944 /* Hard sector size and max sectors impersonate the equiv. hardware. */
945 blk_queue_logical_block_size(rq, info->sector_size);
946 blk_queue_physical_block_size(rq, info->physical_sector_size);
947 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
948
949 /* Each segment in a request is up to an aligned page in size. */
950 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
951 blk_queue_max_segment_size(rq, PAGE_SIZE);
952
953 /* Ensure a merged request will fit in a single I/O ring slot. */
954 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
955
956 /* Make sure buffer addresses are sector-aligned. */
957 blk_queue_dma_alignment(rq, 511);
958}
959
960static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
961 unsigned int physical_sector_size)
962{
963 struct request_queue *rq;
964 struct blkfront_info *info = gd->private_data;
965
966 memset(&info->tag_set, 0, sizeof(info->tag_set));
967 info->tag_set.ops = &blkfront_mq_ops;
968 info->tag_set.nr_hw_queues = info->nr_rings;
969 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
970 /*
971 * When indirect descriptior is not supported, the I/O request
972 * will be split between multiple request in the ring.
973 * To avoid problems when sending the request, divide by
974 * 2 the depth of the queue.
975 */
976 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
977 } else
978 info->tag_set.queue_depth = BLK_RING_SIZE(info);
979 info->tag_set.numa_node = NUMA_NO_NODE;
980 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
981 info->tag_set.cmd_size = sizeof(struct blkif_req);
982 info->tag_set.driver_data = info;
983
984 if (blk_mq_alloc_tag_set(&info->tag_set))
985 return -EINVAL;
986 rq = blk_mq_init_queue(&info->tag_set);
987 if (IS_ERR(rq)) {
988 blk_mq_free_tag_set(&info->tag_set);
989 return PTR_ERR(rq);
990 }
991
992 rq->queuedata = info;
993 info->rq = gd->queue = rq;
994 info->gd = gd;
995 info->sector_size = sector_size;
996 info->physical_sector_size = physical_sector_size;
997 blkif_set_queue_limits(info);
998
999 return 0;
1000}
1001
1002static const char *flush_info(struct blkfront_info *info)
1003{
1004 if (info->feature_flush && info->feature_fua)
1005 return "barrier: enabled;";
1006 else if (info->feature_flush)
1007 return "flush diskcache: enabled;";
1008 else
1009 return "barrier or flush: disabled;";
1010}
1011
1012static void xlvbd_flush(struct blkfront_info *info)
1013{
1014 blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
1015 info->feature_fua ? true : false);
1016 pr_info("blkfront: %s: %s %s %s %s %s\n",
1017 info->gd->disk_name, flush_info(info),
1018 "persistent grants:", info->feature_persistent ?
1019 "enabled;" : "disabled;", "indirect descriptors:",
1020 info->max_indirect_segments ? "enabled;" : "disabled;");
1021}
1022
1023static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1024{
1025 int major;
1026 major = BLKIF_MAJOR(vdevice);
1027 *minor = BLKIF_MINOR(vdevice);
1028 switch (major) {
1029 case XEN_IDE0_MAJOR:
1030 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1031 *minor = ((*minor / 64) * PARTS_PER_DISK) +
1032 EMULATED_HD_DISK_MINOR_OFFSET;
1033 break;
1034 case XEN_IDE1_MAJOR:
1035 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1036 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1037 EMULATED_HD_DISK_MINOR_OFFSET;
1038 break;
1039 case XEN_SCSI_DISK0_MAJOR:
1040 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1041 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1042 break;
1043 case XEN_SCSI_DISK1_MAJOR:
1044 case XEN_SCSI_DISK2_MAJOR:
1045 case XEN_SCSI_DISK3_MAJOR:
1046 case XEN_SCSI_DISK4_MAJOR:
1047 case XEN_SCSI_DISK5_MAJOR:
1048 case XEN_SCSI_DISK6_MAJOR:
1049 case XEN_SCSI_DISK7_MAJOR:
1050 *offset = (*minor / PARTS_PER_DISK) +
1051 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1052 EMULATED_SD_DISK_NAME_OFFSET;
1053 *minor = *minor +
1054 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1055 EMULATED_SD_DISK_MINOR_OFFSET;
1056 break;
1057 case XEN_SCSI_DISK8_MAJOR:
1058 case XEN_SCSI_DISK9_MAJOR:
1059 case XEN_SCSI_DISK10_MAJOR:
1060 case XEN_SCSI_DISK11_MAJOR:
1061 case XEN_SCSI_DISK12_MAJOR:
1062 case XEN_SCSI_DISK13_MAJOR:
1063 case XEN_SCSI_DISK14_MAJOR:
1064 case XEN_SCSI_DISK15_MAJOR:
1065 *offset = (*minor / PARTS_PER_DISK) +
1066 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1067 EMULATED_SD_DISK_NAME_OFFSET;
1068 *minor = *minor +
1069 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1070 EMULATED_SD_DISK_MINOR_OFFSET;
1071 break;
1072 case XENVBD_MAJOR:
1073 *offset = *minor / PARTS_PER_DISK;
1074 break;
1075 default:
1076 printk(KERN_WARNING "blkfront: your disk configuration is "
1077 "incorrect, please use an xvd device instead\n");
1078 return -ENODEV;
1079 }
1080 return 0;
1081}
1082
1083static char *encode_disk_name(char *ptr, unsigned int n)
1084{
1085 if (n >= 26)
1086 ptr = encode_disk_name(ptr, n / 26 - 1);
1087 *ptr = 'a' + n % 26;
1088 return ptr + 1;
1089}
1090
1091static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1092 struct blkfront_info *info,
1093 u16 vdisk_info, u16 sector_size,
1094 unsigned int physical_sector_size)
1095{
1096 struct gendisk *gd;
1097 int nr_minors = 1;
1098 int err;
1099 unsigned int offset;
1100 int minor;
1101 int nr_parts;
1102 char *ptr;
1103
1104 BUG_ON(info->gd != NULL);
1105 BUG_ON(info->rq != NULL);
1106
1107 if ((info->vdevice>>EXT_SHIFT) > 1) {
1108 /* this is above the extended range; something is wrong */
1109 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1110 return -ENODEV;
1111 }
1112
1113 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1114 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1115 if (err)
1116 return err;
1117 nr_parts = PARTS_PER_DISK;
1118 } else {
1119 minor = BLKIF_MINOR_EXT(info->vdevice);
1120 nr_parts = PARTS_PER_EXT_DISK;
1121 offset = minor / nr_parts;
1122 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1123 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1124 "emulated IDE disks,\n\t choose an xvd device name"
1125 "from xvde on\n", info->vdevice);
1126 }
1127 if (minor >> MINORBITS) {
1128 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1129 info->vdevice, minor);
1130 return -ENODEV;
1131 }
1132
1133 if ((minor % nr_parts) == 0)
1134 nr_minors = nr_parts;
1135
1136 err = xlbd_reserve_minors(minor, nr_minors);
1137 if (err)
1138 goto out;
1139 err = -ENODEV;
1140
1141 gd = alloc_disk(nr_minors);
1142 if (gd == NULL)
1143 goto release;
1144
1145 strcpy(gd->disk_name, DEV_NAME);
1146 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1147 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1148 if (nr_minors > 1)
1149 *ptr = 0;
1150 else
1151 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1152 "%d", minor & (nr_parts - 1));
1153
1154 gd->major = XENVBD_MAJOR;
1155 gd->first_minor = minor;
1156 gd->fops = &xlvbd_block_fops;
1157 gd->private_data = info;
1158 set_capacity(gd, capacity);
1159
1160 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
1161 del_gendisk(gd);
1162 goto release;
1163 }
1164
1165 xlvbd_flush(info);
1166
1167 if (vdisk_info & VDISK_READONLY)
1168 set_disk_ro(gd, 1);
1169
1170 if (vdisk_info & VDISK_REMOVABLE)
1171 gd->flags |= GENHD_FL_REMOVABLE;
1172
1173 if (vdisk_info & VDISK_CDROM)
1174 gd->flags |= GENHD_FL_CD;
1175
1176 return 0;
1177
1178 release:
1179 xlbd_release_minors(minor, nr_minors);
1180 out:
1181 return err;
1182}
1183
1184static void xlvbd_release_gendisk(struct blkfront_info *info)
1185{
1186 unsigned int minor, nr_minors, i;
1187
1188 if (info->rq == NULL)
1189 return;
1190
1191 /* No more blkif_request(). */
1192 blk_mq_stop_hw_queues(info->rq);
1193
1194 for (i = 0; i < info->nr_rings; i++) {
1195 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1196
1197 /* No more gnttab callback work. */
1198 gnttab_cancel_free_callback(&rinfo->callback);
1199
1200 /* Flush gnttab callback work. Must be done with no locks held. */
1201 flush_work(&rinfo->work);
1202 }
1203
1204 del_gendisk(info->gd);
1205
1206 minor = info->gd->first_minor;
1207 nr_minors = info->gd->minors;
1208 xlbd_release_minors(minor, nr_minors);
1209
1210 blk_cleanup_queue(info->rq);
1211 blk_mq_free_tag_set(&info->tag_set);
1212 info->rq = NULL;
1213
1214 put_disk(info->gd);
1215 info->gd = NULL;
1216}
1217
1218/* Already hold rinfo->ring_lock. */
1219static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1220{
1221 if (!RING_FULL(&rinfo->ring))
1222 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1223}
1224
1225static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1226{
1227 unsigned long flags;
1228
1229 spin_lock_irqsave(&rinfo->ring_lock, flags);
1230 kick_pending_request_queues_locked(rinfo);
1231 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1232}
1233
1234static void blkif_restart_queue(struct work_struct *work)
1235{
1236 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1237
1238 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1239 kick_pending_request_queues(rinfo);
1240}
1241
1242static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1243{
1244 struct grant *persistent_gnt, *n;
1245 struct blkfront_info *info = rinfo->dev_info;
1246 int i, j, segs;
1247
1248 /*
1249 * Remove indirect pages, this only happens when using indirect
1250 * descriptors but not persistent grants
1251 */
1252 if (!list_empty(&rinfo->indirect_pages)) {
1253 struct page *indirect_page, *n;
1254
1255 BUG_ON(info->feature_persistent);
1256 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1257 list_del(&indirect_page->lru);
1258 __free_page(indirect_page);
1259 }
1260 }
1261
1262 /* Remove all persistent grants. */
1263 if (!list_empty(&rinfo->grants)) {
1264 list_for_each_entry_safe(persistent_gnt, n,
1265 &rinfo->grants, node) {
1266 list_del(&persistent_gnt->node);
1267 if (persistent_gnt->gref != GRANT_INVALID_REF) {
1268 gnttab_end_foreign_access(persistent_gnt->gref,
1269 0, 0UL);
1270 rinfo->persistent_gnts_c--;
1271 }
1272 if (info->feature_persistent)
1273 __free_page(persistent_gnt->page);
1274 kfree(persistent_gnt);
1275 }
1276 }
1277 BUG_ON(rinfo->persistent_gnts_c != 0);
1278
1279 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1280 /*
1281 * Clear persistent grants present in requests already
1282 * on the shared ring
1283 */
1284 if (!rinfo->shadow[i].request)
1285 goto free_shadow;
1286
1287 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1288 rinfo->shadow[i].req.u.indirect.nr_segments :
1289 rinfo->shadow[i].req.u.rw.nr_segments;
1290 for (j = 0; j < segs; j++) {
1291 persistent_gnt = rinfo->shadow[i].grants_used[j];
1292 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1293 if (info->feature_persistent)
1294 __free_page(persistent_gnt->page);
1295 kfree(persistent_gnt);
1296 }
1297
1298 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1299 /*
1300 * If this is not an indirect operation don't try to
1301 * free indirect segments
1302 */
1303 goto free_shadow;
1304
1305 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1306 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1307 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1308 __free_page(persistent_gnt->page);
1309 kfree(persistent_gnt);
1310 }
1311
1312free_shadow:
1313 kvfree(rinfo->shadow[i].grants_used);
1314 rinfo->shadow[i].grants_used = NULL;
1315 kvfree(rinfo->shadow[i].indirect_grants);
1316 rinfo->shadow[i].indirect_grants = NULL;
1317 kvfree(rinfo->shadow[i].sg);
1318 rinfo->shadow[i].sg = NULL;
1319 }
1320
1321 /* No more gnttab callback work. */
1322 gnttab_cancel_free_callback(&rinfo->callback);
1323
1324 /* Flush gnttab callback work. Must be done with no locks held. */
1325 flush_work(&rinfo->work);
1326
1327 /* Free resources associated with old device channel. */
1328 for (i = 0; i < info->nr_ring_pages; i++) {
1329 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1330 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1331 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1332 }
1333 }
1334 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1335 rinfo->ring.sring = NULL;
1336
1337 if (rinfo->irq)
1338 unbind_from_irqhandler(rinfo->irq, rinfo);
1339 rinfo->evtchn = rinfo->irq = 0;
1340}
1341
1342static void blkif_free(struct blkfront_info *info, int suspend)
1343{
1344 unsigned int i;
1345
1346 /* Prevent new requests being issued until we fix things up. */
1347 info->connected = suspend ?
1348 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1349 /* No more blkif_request(). */
1350 if (info->rq)
1351 blk_mq_stop_hw_queues(info->rq);
1352
1353 for (i = 0; i < info->nr_rings; i++)
1354 blkif_free_ring(&info->rinfo[i]);
1355
1356 kvfree(info->rinfo);
1357 info->rinfo = NULL;
1358 info->nr_rings = 0;
1359}
1360
1361struct copy_from_grant {
1362 const struct blk_shadow *s;
1363 unsigned int grant_idx;
1364 unsigned int bvec_offset;
1365 char *bvec_data;
1366};
1367
1368static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1369 unsigned int len, void *data)
1370{
1371 struct copy_from_grant *info = data;
1372 char *shared_data;
1373 /* Convenient aliases */
1374 const struct blk_shadow *s = info->s;
1375
1376 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1377
1378 memcpy(info->bvec_data + info->bvec_offset,
1379 shared_data + offset, len);
1380
1381 info->bvec_offset += len;
1382 info->grant_idx++;
1383
1384 kunmap_atomic(shared_data);
1385}
1386
1387static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1388{
1389 switch (rsp)
1390 {
1391 case BLKIF_RSP_OKAY:
1392 return REQ_DONE;
1393 case BLKIF_RSP_EOPNOTSUPP:
1394 return REQ_EOPNOTSUPP;
1395 case BLKIF_RSP_ERROR:
1396 /* Fallthrough. */
1397 default:
1398 return REQ_ERROR;
1399 }
1400}
1401
1402/*
1403 * Get the final status of the block request based on two ring response
1404 */
1405static int blkif_get_final_status(enum blk_req_status s1,
1406 enum blk_req_status s2)
1407{
1408 BUG_ON(s1 == REQ_WAITING);
1409 BUG_ON(s2 == REQ_WAITING);
1410
1411 if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1412 return BLKIF_RSP_ERROR;
1413 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1414 return BLKIF_RSP_EOPNOTSUPP;
1415 return BLKIF_RSP_OKAY;
1416}
1417
1418static bool blkif_completion(unsigned long *id,
1419 struct blkfront_ring_info *rinfo,
1420 struct blkif_response *bret)
1421{
1422 int i = 0;
1423 struct scatterlist *sg;
1424 int num_sg, num_grant;
1425 struct blkfront_info *info = rinfo->dev_info;
1426 struct blk_shadow *s = &rinfo->shadow[*id];
1427 struct copy_from_grant data = {
1428 .grant_idx = 0,
1429 };
1430
1431 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1432 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1433
1434 /* The I/O request may be split in two. */
1435 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1436 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1437
1438 /* Keep the status of the current response in shadow. */
1439 s->status = blkif_rsp_to_req_status(bret->status);
1440
1441 /* Wait the second response if not yet here. */
1442 if (s2->status == REQ_WAITING)
1443 return false;
1444
1445 bret->status = blkif_get_final_status(s->status,
1446 s2->status);
1447
1448 /*
1449 * All the grants is stored in the first shadow in order
1450 * to make the completion code simpler.
1451 */
1452 num_grant += s2->req.u.rw.nr_segments;
1453
1454 /*
1455 * The two responses may not come in order. Only the
1456 * first request will store the scatter-gather list.
1457 */
1458 if (s2->num_sg != 0) {
1459 /* Update "id" with the ID of the first response. */
1460 *id = s->associated_id;
1461 s = s2;
1462 }
1463
1464 /*
1465 * We don't need anymore the second request, so recycling
1466 * it now.
1467 */
1468 if (add_id_to_freelist(rinfo, s->associated_id))
1469 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1470 info->gd->disk_name, s->associated_id);
1471 }
1472
1473 data.s = s;
1474 num_sg = s->num_sg;
1475
1476 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1477 for_each_sg(s->sg, sg, num_sg, i) {
1478 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1479
1480 data.bvec_offset = sg->offset;
1481 data.bvec_data = kmap_atomic(sg_page(sg));
1482
1483 gnttab_foreach_grant_in_range(sg_page(sg),
1484 sg->offset,
1485 sg->length,
1486 blkif_copy_from_grant,
1487 &data);
1488
1489 kunmap_atomic(data.bvec_data);
1490 }
1491 }
1492 /* Add the persistent grant into the list of free grants */
1493 for (i = 0; i < num_grant; i++) {
1494 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1495 /*
1496 * If the grant is still mapped by the backend (the
1497 * backend has chosen to make this grant persistent)
1498 * we add it at the head of the list, so it will be
1499 * reused first.
1500 */
1501 if (!info->feature_persistent)
1502 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1503 s->grants_used[i]->gref);
1504 list_add(&s->grants_used[i]->node, &rinfo->grants);
1505 rinfo->persistent_gnts_c++;
1506 } else {
1507 /*
1508 * If the grant is not mapped by the backend we end the
1509 * foreign access and add it to the tail of the list,
1510 * so it will not be picked again unless we run out of
1511 * persistent grants.
1512 */
1513 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1514 s->grants_used[i]->gref = GRANT_INVALID_REF;
1515 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1516 }
1517 }
1518 if (s->req.operation == BLKIF_OP_INDIRECT) {
1519 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1520 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1521 if (!info->feature_persistent)
1522 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1523 s->indirect_grants[i]->gref);
1524 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1525 rinfo->persistent_gnts_c++;
1526 } else {
1527 struct page *indirect_page;
1528
1529 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1530 /*
1531 * Add the used indirect page back to the list of
1532 * available pages for indirect grefs.
1533 */
1534 if (!info->feature_persistent) {
1535 indirect_page = s->indirect_grants[i]->page;
1536 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1537 }
1538 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1539 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1540 }
1541 }
1542 }
1543
1544 return true;
1545}
1546
1547static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1548{
1549 struct request *req;
1550 struct blkif_response *bret;
1551 RING_IDX i, rp;
1552 unsigned long flags;
1553 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1554 struct blkfront_info *info = rinfo->dev_info;
1555
1556 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1557 return IRQ_HANDLED;
1558
1559 spin_lock_irqsave(&rinfo->ring_lock, flags);
1560 again:
1561 rp = rinfo->ring.sring->rsp_prod;
1562 rmb(); /* Ensure we see queued responses up to 'rp'. */
1563
1564 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1565 unsigned long id;
1566
1567 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1568 id = bret->id;
1569 /*
1570 * The backend has messed up and given us an id that we would
1571 * never have given to it (we stamp it up to BLK_RING_SIZE -
1572 * look in get_id_from_freelist.
1573 */
1574 if (id >= BLK_RING_SIZE(info)) {
1575 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1576 info->gd->disk_name, op_name(bret->operation), id);
1577 /* We can't safely get the 'struct request' as
1578 * the id is busted. */
1579 continue;
1580 }
1581 req = rinfo->shadow[id].request;
1582
1583 if (bret->operation != BLKIF_OP_DISCARD) {
1584 /*
1585 * We may need to wait for an extra response if the
1586 * I/O request is split in 2
1587 */
1588 if (!blkif_completion(&id, rinfo, bret))
1589 continue;
1590 }
1591
1592 if (add_id_to_freelist(rinfo, id)) {
1593 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1594 info->gd->disk_name, op_name(bret->operation), id);
1595 continue;
1596 }
1597
1598 if (bret->status == BLKIF_RSP_OKAY)
1599 blkif_req(req)->error = BLK_STS_OK;
1600 else
1601 blkif_req(req)->error = BLK_STS_IOERR;
1602
1603 switch (bret->operation) {
1604 case BLKIF_OP_DISCARD:
1605 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1606 struct request_queue *rq = info->rq;
1607 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1608 info->gd->disk_name, op_name(bret->operation));
1609 blkif_req(req)->error = BLK_STS_NOTSUPP;
1610 info->feature_discard = 0;
1611 info->feature_secdiscard = 0;
1612 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1613 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1614 }
1615 break;
1616 case BLKIF_OP_FLUSH_DISKCACHE:
1617 case BLKIF_OP_WRITE_BARRIER:
1618 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1619 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1620 info->gd->disk_name, op_name(bret->operation));
1621 blkif_req(req)->error = BLK_STS_NOTSUPP;
1622 }
1623 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1624 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1625 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1626 info->gd->disk_name, op_name(bret->operation));
1627 blkif_req(req)->error = BLK_STS_NOTSUPP;
1628 }
1629 if (unlikely(blkif_req(req)->error)) {
1630 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1631 blkif_req(req)->error = BLK_STS_OK;
1632 info->feature_fua = 0;
1633 info->feature_flush = 0;
1634 xlvbd_flush(info);
1635 }
1636 /* fall through */
1637 case BLKIF_OP_READ:
1638 case BLKIF_OP_WRITE:
1639 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1640 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1641 "request: %x\n", bret->status);
1642
1643 break;
1644 default:
1645 BUG();
1646 }
1647
1648 blk_mq_complete_request(req);
1649 }
1650
1651 rinfo->ring.rsp_cons = i;
1652
1653 if (i != rinfo->ring.req_prod_pvt) {
1654 int more_to_do;
1655 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1656 if (more_to_do)
1657 goto again;
1658 } else
1659 rinfo->ring.sring->rsp_event = i + 1;
1660
1661 kick_pending_request_queues_locked(rinfo);
1662
1663 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1664
1665 return IRQ_HANDLED;
1666}
1667
1668
1669static int setup_blkring(struct xenbus_device *dev,
1670 struct blkfront_ring_info *rinfo)
1671{
1672 struct blkif_sring *sring;
1673 int err, i;
1674 struct blkfront_info *info = rinfo->dev_info;
1675 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1676 grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1677
1678 for (i = 0; i < info->nr_ring_pages; i++)
1679 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1680
1681 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1682 get_order(ring_size));
1683 if (!sring) {
1684 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1685 return -ENOMEM;
1686 }
1687 SHARED_RING_INIT(sring);
1688 FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1689
1690 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1691 if (err < 0) {
1692 free_pages((unsigned long)sring, get_order(ring_size));
1693 rinfo->ring.sring = NULL;
1694 goto fail;
1695 }
1696 for (i = 0; i < info->nr_ring_pages; i++)
1697 rinfo->ring_ref[i] = gref[i];
1698
1699 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1700 if (err)
1701 goto fail;
1702
1703 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1704 "blkif", rinfo);
1705 if (err <= 0) {
1706 xenbus_dev_fatal(dev, err,
1707 "bind_evtchn_to_irqhandler failed");
1708 goto fail;
1709 }
1710 rinfo->irq = err;
1711
1712 return 0;
1713fail:
1714 blkif_free(info, 0);
1715 return err;
1716}
1717
1718/*
1719 * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1720 * ring buffer may have multi pages depending on ->nr_ring_pages.
1721 */
1722static int write_per_ring_nodes(struct xenbus_transaction xbt,
1723 struct blkfront_ring_info *rinfo, const char *dir)
1724{
1725 int err;
1726 unsigned int i;
1727 const char *message = NULL;
1728 struct blkfront_info *info = rinfo->dev_info;
1729
1730 if (info->nr_ring_pages == 1) {
1731 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1732 if (err) {
1733 message = "writing ring-ref";
1734 goto abort_transaction;
1735 }
1736 } else {
1737 for (i = 0; i < info->nr_ring_pages; i++) {
1738 char ring_ref_name[RINGREF_NAME_LEN];
1739
1740 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1741 err = xenbus_printf(xbt, dir, ring_ref_name,
1742 "%u", rinfo->ring_ref[i]);
1743 if (err) {
1744 message = "writing ring-ref";
1745 goto abort_transaction;
1746 }
1747 }
1748 }
1749
1750 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1751 if (err) {
1752 message = "writing event-channel";
1753 goto abort_transaction;
1754 }
1755
1756 return 0;
1757
1758abort_transaction:
1759 xenbus_transaction_end(xbt, 1);
1760 if (message)
1761 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1762
1763 return err;
1764}
1765
1766static void free_info(struct blkfront_info *info)
1767{
1768 list_del(&info->info_list);
1769 kfree(info);
1770}
1771
1772/* Common code used when first setting up, and when resuming. */
1773static int talk_to_blkback(struct xenbus_device *dev,
1774 struct blkfront_info *info)
1775{
1776 const char *message = NULL;
1777 struct xenbus_transaction xbt;
1778 int err;
1779 unsigned int i, max_page_order;
1780 unsigned int ring_page_order;
1781
1782 if (!info)
1783 return -ENODEV;
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 (i = 0; i < info->nr_rings; i++) {
1795 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1796
1797 /* Create shared ring, alloc event channel. */
1798 err = setup_blkring(dev, rinfo);
1799 if (err)
1800 goto destroy_blkring;
1801 }
1802
1803again:
1804 err = xenbus_transaction_start(&xbt);
1805 if (err) {
1806 xenbus_dev_fatal(dev, err, "starting transaction");
1807 goto destroy_blkring;
1808 }
1809
1810 if (info->nr_ring_pages > 1) {
1811 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1812 ring_page_order);
1813 if (err) {
1814 message = "writing ring-page-order";
1815 goto abort_transaction;
1816 }
1817 }
1818
1819 /* We already got the number of queues/rings in _probe */
1820 if (info->nr_rings == 1) {
1821 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1822 if (err)
1823 goto destroy_blkring;
1824 } else {
1825 char *path;
1826 size_t pathsize;
1827
1828 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1829 info->nr_rings);
1830 if (err) {
1831 message = "writing multi-queue-num-queues";
1832 goto abort_transaction;
1833 }
1834
1835 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1836 path = kmalloc(pathsize, GFP_KERNEL);
1837 if (!path) {
1838 err = -ENOMEM;
1839 message = "ENOMEM while writing ring references";
1840 goto abort_transaction;
1841 }
1842
1843 for (i = 0; i < info->nr_rings; i++) {
1844 memset(path, 0, pathsize);
1845 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1846 err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1847 if (err) {
1848 kfree(path);
1849 goto destroy_blkring;
1850 }
1851 }
1852 kfree(path);
1853 }
1854 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1855 XEN_IO_PROTO_ABI_NATIVE);
1856 if (err) {
1857 message = "writing protocol";
1858 goto abort_transaction;
1859 }
1860 err = xenbus_printf(xbt, dev->nodename,
1861 "feature-persistent", "%u", 1);
1862 if (err)
1863 dev_warn(&dev->dev,
1864 "writing persistent grants feature to xenbus");
1865
1866 err = xenbus_transaction_end(xbt, 0);
1867 if (err) {
1868 if (err == -EAGAIN)
1869 goto again;
1870 xenbus_dev_fatal(dev, err, "completing transaction");
1871 goto destroy_blkring;
1872 }
1873
1874 for (i = 0; i < info->nr_rings; i++) {
1875 unsigned int j;
1876 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1877
1878 for (j = 0; j < BLK_RING_SIZE(info); j++)
1879 rinfo->shadow[j].req.u.rw.id = j + 1;
1880 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1881 }
1882 xenbus_switch_state(dev, XenbusStateInitialised);
1883
1884 return 0;
1885
1886 abort_transaction:
1887 xenbus_transaction_end(xbt, 1);
1888 if (message)
1889 xenbus_dev_fatal(dev, err, "%s", message);
1890 destroy_blkring:
1891 blkif_free(info, 0);
1892
1893 mutex_lock(&blkfront_mutex);
1894 free_info(info);
1895 mutex_unlock(&blkfront_mutex);
1896
1897 dev_set_drvdata(&dev->dev, NULL);
1898
1899 return err;
1900}
1901
1902static int negotiate_mq(struct blkfront_info *info)
1903{
1904 unsigned int backend_max_queues;
1905 unsigned int i;
1906
1907 BUG_ON(info->nr_rings);
1908
1909 /* Check if backend supports multiple queues. */
1910 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1911 "multi-queue-max-queues", 1);
1912 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1913 /* We need at least one ring. */
1914 if (!info->nr_rings)
1915 info->nr_rings = 1;
1916
1917 info->rinfo = kvcalloc(info->nr_rings,
1918 sizeof(struct blkfront_ring_info),
1919 GFP_KERNEL);
1920 if (!info->rinfo) {
1921 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1922 info->nr_rings = 0;
1923 return -ENOMEM;
1924 }
1925
1926 for (i = 0; i < info->nr_rings; i++) {
1927 struct blkfront_ring_info *rinfo;
1928
1929 rinfo = &info->rinfo[i];
1930 INIT_LIST_HEAD(&rinfo->indirect_pages);
1931 INIT_LIST_HEAD(&rinfo->grants);
1932 rinfo->dev_info = info;
1933 INIT_WORK(&rinfo->work, blkif_restart_queue);
1934 spin_lock_init(&rinfo->ring_lock);
1935 }
1936 return 0;
1937}
1938/**
1939 * Entry point to this code when a new device is created. Allocate the basic
1940 * structures and the ring buffer for communication with the backend, and
1941 * inform the backend of the appropriate details for those. Switch to
1942 * Initialised state.
1943 */
1944static int blkfront_probe(struct xenbus_device *dev,
1945 const struct xenbus_device_id *id)
1946{
1947 int err, vdevice;
1948 struct blkfront_info *info;
1949
1950 /* FIXME: Use dynamic device id if this is not set. */
1951 err = xenbus_scanf(XBT_NIL, dev->nodename,
1952 "virtual-device", "%i", &vdevice);
1953 if (err != 1) {
1954 /* go looking in the extended area instead */
1955 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1956 "%i", &vdevice);
1957 if (err != 1) {
1958 xenbus_dev_fatal(dev, err, "reading virtual-device");
1959 return err;
1960 }
1961 }
1962
1963 if (xen_hvm_domain()) {
1964 char *type;
1965 int len;
1966 /* no unplug has been done: do not hook devices != xen vbds */
1967 if (xen_has_pv_and_legacy_disk_devices()) {
1968 int major;
1969
1970 if (!VDEV_IS_EXTENDED(vdevice))
1971 major = BLKIF_MAJOR(vdevice);
1972 else
1973 major = XENVBD_MAJOR;
1974
1975 if (major != XENVBD_MAJOR) {
1976 printk(KERN_INFO
1977 "%s: HVM does not support vbd %d as xen block device\n",
1978 __func__, vdevice);
1979 return -ENODEV;
1980 }
1981 }
1982 /* do not create a PV cdrom device if we are an HVM guest */
1983 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1984 if (IS_ERR(type))
1985 return -ENODEV;
1986 if (strncmp(type, "cdrom", 5) == 0) {
1987 kfree(type);
1988 return -ENODEV;
1989 }
1990 kfree(type);
1991 }
1992 info = kzalloc(sizeof(*info), GFP_KERNEL);
1993 if (!info) {
1994 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1995 return -ENOMEM;
1996 }
1997
1998 info->xbdev = dev;
1999
2000 mutex_init(&info->mutex);
2001 info->vdevice = vdevice;
2002 info->connected = BLKIF_STATE_DISCONNECTED;
2003
2004 /* Front end dir is a number, which is used as the id. */
2005 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
2006 dev_set_drvdata(&dev->dev, info);
2007
2008 mutex_lock(&blkfront_mutex);
2009 list_add(&info->info_list, &info_list);
2010 mutex_unlock(&blkfront_mutex);
2011
2012 return 0;
2013}
2014
2015static int blkif_recover(struct blkfront_info *info)
2016{
2017 unsigned int r_index;
2018 struct request *req, *n;
2019 int rc;
2020 struct bio *bio;
2021 unsigned int segs;
2022
2023 blkfront_gather_backend_features(info);
2024 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2025 blkif_set_queue_limits(info);
2026 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2027 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2028
2029 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2030 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2031
2032 rc = blkfront_setup_indirect(rinfo);
2033 if (rc)
2034 return rc;
2035 }
2036 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2037
2038 /* Now safe for us to use the shared ring */
2039 info->connected = BLKIF_STATE_CONNECTED;
2040
2041 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2042 struct blkfront_ring_info *rinfo;
2043
2044 rinfo = &info->rinfo[r_index];
2045 /* Kick any other new requests queued since we resumed */
2046 kick_pending_request_queues(rinfo);
2047 }
2048
2049 list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2050 /* Requeue pending requests (flush or discard) */
2051 list_del_init(&req->queuelist);
2052 BUG_ON(req->nr_phys_segments > segs);
2053 blk_mq_requeue_request(req, false);
2054 }
2055 blk_mq_start_stopped_hw_queues(info->rq, true);
2056 blk_mq_kick_requeue_list(info->rq);
2057
2058 while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2059 /* Traverse the list of pending bios and re-queue them */
2060 submit_bio(bio);
2061 }
2062
2063 return 0;
2064}
2065
2066/**
2067 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2068 * driver restart. We tear down our blkif structure and recreate it, but
2069 * leave the device-layer structures intact so that this is transparent to the
2070 * rest of the kernel.
2071 */
2072static int blkfront_resume(struct xenbus_device *dev)
2073{
2074 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2075 int err = 0;
2076 unsigned int i, j;
2077
2078 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2079
2080 bio_list_init(&info->bio_list);
2081 INIT_LIST_HEAD(&info->requests);
2082 for (i = 0; i < info->nr_rings; i++) {
2083 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2084 struct bio_list merge_bio;
2085 struct blk_shadow *shadow = rinfo->shadow;
2086
2087 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2088 /* Not in use? */
2089 if (!shadow[j].request)
2090 continue;
2091
2092 /*
2093 * Get the bios in the request so we can re-queue them.
2094 */
2095 if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2096 req_op(shadow[j].request) == REQ_OP_DISCARD ||
2097 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2098 shadow[j].request->cmd_flags & REQ_FUA) {
2099 /*
2100 * Flush operations don't contain bios, so
2101 * we need to requeue the whole request
2102 *
2103 * XXX: but this doesn't make any sense for a
2104 * write with the FUA flag set..
2105 */
2106 list_add(&shadow[j].request->queuelist, &info->requests);
2107 continue;
2108 }
2109 merge_bio.head = shadow[j].request->bio;
2110 merge_bio.tail = shadow[j].request->biotail;
2111 bio_list_merge(&info->bio_list, &merge_bio);
2112 shadow[j].request->bio = NULL;
2113 blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2114 }
2115 }
2116
2117 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2118
2119 err = talk_to_blkback(dev, info);
2120 if (!err)
2121 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2122
2123 /*
2124 * We have to wait for the backend to switch to
2125 * connected state, since we want to read which
2126 * features it supports.
2127 */
2128
2129 return err;
2130}
2131
2132static void blkfront_closing(struct blkfront_info *info)
2133{
2134 struct xenbus_device *xbdev = info->xbdev;
2135 struct block_device *bdev = NULL;
2136
2137 mutex_lock(&info->mutex);
2138
2139 if (xbdev->state == XenbusStateClosing) {
2140 mutex_unlock(&info->mutex);
2141 return;
2142 }
2143
2144 if (info->gd)
2145 bdev = bdget_disk(info->gd, 0);
2146
2147 mutex_unlock(&info->mutex);
2148
2149 if (!bdev) {
2150 xenbus_frontend_closed(xbdev);
2151 return;
2152 }
2153
2154 mutex_lock(&bdev->bd_mutex);
2155
2156 if (bdev->bd_openers) {
2157 xenbus_dev_error(xbdev, -EBUSY,
2158 "Device in use; refusing to close");
2159 xenbus_switch_state(xbdev, XenbusStateClosing);
2160 } else {
2161 xlvbd_release_gendisk(info);
2162 xenbus_frontend_closed(xbdev);
2163 }
2164
2165 mutex_unlock(&bdev->bd_mutex);
2166 bdput(bdev);
2167}
2168
2169static void blkfront_setup_discard(struct blkfront_info *info)
2170{
2171 int err;
2172 unsigned int discard_granularity;
2173 unsigned int discard_alignment;
2174
2175 info->feature_discard = 1;
2176 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2177 "discard-granularity", "%u", &discard_granularity,
2178 "discard-alignment", "%u", &discard_alignment,
2179 NULL);
2180 if (!err) {
2181 info->discard_granularity = discard_granularity;
2182 info->discard_alignment = discard_alignment;
2183 }
2184 info->feature_secdiscard =
2185 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2186 0);
2187}
2188
2189static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2190{
2191 unsigned int psegs, grants;
2192 int err, i;
2193 struct blkfront_info *info = rinfo->dev_info;
2194
2195 if (info->max_indirect_segments == 0) {
2196 if (!HAS_EXTRA_REQ)
2197 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2198 else {
2199 /*
2200 * When an extra req is required, the maximum
2201 * grants supported is related to the size of the
2202 * Linux block segment.
2203 */
2204 grants = GRANTS_PER_PSEG;
2205 }
2206 }
2207 else
2208 grants = info->max_indirect_segments;
2209 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2210
2211 err = fill_grant_buffer(rinfo,
2212 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2213 if (err)
2214 goto out_of_memory;
2215
2216 if (!info->feature_persistent && info->max_indirect_segments) {
2217 /*
2218 * We are using indirect descriptors but not persistent
2219 * grants, we need to allocate a set of pages that can be
2220 * used for mapping indirect grefs
2221 */
2222 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2223
2224 BUG_ON(!list_empty(&rinfo->indirect_pages));
2225 for (i = 0; i < num; i++) {
2226 struct page *indirect_page = alloc_page(GFP_NOIO);
2227 if (!indirect_page)
2228 goto out_of_memory;
2229 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2230 }
2231 }
2232
2233 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2234 rinfo->shadow[i].grants_used =
2235 kvcalloc(grants,
2236 sizeof(rinfo->shadow[i].grants_used[0]),
2237 GFP_NOIO);
2238 rinfo->shadow[i].sg = kvcalloc(psegs,
2239 sizeof(rinfo->shadow[i].sg[0]),
2240 GFP_NOIO);
2241 if (info->max_indirect_segments)
2242 rinfo->shadow[i].indirect_grants =
2243 kvcalloc(INDIRECT_GREFS(grants),
2244 sizeof(rinfo->shadow[i].indirect_grants[0]),
2245 GFP_NOIO);
2246 if ((rinfo->shadow[i].grants_used == NULL) ||
2247 (rinfo->shadow[i].sg == NULL) ||
2248 (info->max_indirect_segments &&
2249 (rinfo->shadow[i].indirect_grants == NULL)))
2250 goto out_of_memory;
2251 sg_init_table(rinfo->shadow[i].sg, psegs);
2252 }
2253
2254
2255 return 0;
2256
2257out_of_memory:
2258 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2259 kvfree(rinfo->shadow[i].grants_used);
2260 rinfo->shadow[i].grants_used = NULL;
2261 kvfree(rinfo->shadow[i].sg);
2262 rinfo->shadow[i].sg = NULL;
2263 kvfree(rinfo->shadow[i].indirect_grants);
2264 rinfo->shadow[i].indirect_grants = NULL;
2265 }
2266 if (!list_empty(&rinfo->indirect_pages)) {
2267 struct page *indirect_page, *n;
2268 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2269 list_del(&indirect_page->lru);
2270 __free_page(indirect_page);
2271 }
2272 }
2273 return -ENOMEM;
2274}
2275
2276/*
2277 * Gather all backend feature-*
2278 */
2279static void blkfront_gather_backend_features(struct blkfront_info *info)
2280{
2281 unsigned int indirect_segments;
2282
2283 info->feature_flush = 0;
2284 info->feature_fua = 0;
2285
2286 /*
2287 * If there's no "feature-barrier" defined, then it means
2288 * we're dealing with a very old backend which writes
2289 * synchronously; nothing to do.
2290 *
2291 * If there are barriers, then we use flush.
2292 */
2293 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2294 info->feature_flush = 1;
2295 info->feature_fua = 1;
2296 }
2297
2298 /*
2299 * And if there is "feature-flush-cache" use that above
2300 * barriers.
2301 */
2302 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2303 0)) {
2304 info->feature_flush = 1;
2305 info->feature_fua = 0;
2306 }
2307
2308 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2309 blkfront_setup_discard(info);
2310
2311 info->feature_persistent =
2312 !!xenbus_read_unsigned(info->xbdev->otherend,
2313 "feature-persistent", 0);
2314
2315 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2316 "feature-max-indirect-segments", 0);
2317 if (indirect_segments > xen_blkif_max_segments)
2318 indirect_segments = xen_blkif_max_segments;
2319 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2320 indirect_segments = 0;
2321 info->max_indirect_segments = indirect_segments;
2322
2323 if (info->feature_persistent) {
2324 mutex_lock(&blkfront_mutex);
2325 schedule_delayed_work(&blkfront_work, HZ * 10);
2326 mutex_unlock(&blkfront_mutex);
2327 }
2328}
2329
2330/*
2331 * Invoked when the backend is finally 'ready' (and has told produced
2332 * the details about the physical device - #sectors, size, etc).
2333 */
2334static void blkfront_connect(struct blkfront_info *info)
2335{
2336 unsigned long long sectors;
2337 unsigned long sector_size;
2338 unsigned int physical_sector_size;
2339 unsigned int binfo;
2340 char *envp[] = { "RESIZE=1", NULL };
2341 int err, i;
2342
2343 switch (info->connected) {
2344 case BLKIF_STATE_CONNECTED:
2345 /*
2346 * Potentially, the back-end may be signalling
2347 * a capacity change; update the capacity.
2348 */
2349 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2350 "sectors", "%Lu", §ors);
2351 if (XENBUS_EXIST_ERR(err))
2352 return;
2353 printk(KERN_INFO "Setting capacity to %Lu\n",
2354 sectors);
2355 set_capacity(info->gd, sectors);
2356 revalidate_disk(info->gd);
2357 kobject_uevent_env(&disk_to_dev(info->gd)->kobj,
2358 KOBJ_CHANGE, envp);
2359
2360 return;
2361 case BLKIF_STATE_SUSPENDED:
2362 /*
2363 * If we are recovering from suspension, we need to wait
2364 * for the backend to announce it's features before
2365 * reconnecting, at least we need to know if the backend
2366 * supports indirect descriptors, and how many.
2367 */
2368 blkif_recover(info);
2369 return;
2370
2371 default:
2372 break;
2373 }
2374
2375 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2376 __func__, info->xbdev->otherend);
2377
2378 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2379 "sectors", "%llu", §ors,
2380 "info", "%u", &binfo,
2381 "sector-size", "%lu", §or_size,
2382 NULL);
2383 if (err) {
2384 xenbus_dev_fatal(info->xbdev, err,
2385 "reading backend fields at %s",
2386 info->xbdev->otherend);
2387 return;
2388 }
2389
2390 /*
2391 * physcial-sector-size is a newer field, so old backends may not
2392 * provide this. Assume physical sector size to be the same as
2393 * sector_size in that case.
2394 */
2395 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2396 "physical-sector-size",
2397 sector_size);
2398 blkfront_gather_backend_features(info);
2399 for (i = 0; i < info->nr_rings; i++) {
2400 err = blkfront_setup_indirect(&info->rinfo[i]);
2401 if (err) {
2402 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2403 info->xbdev->otherend);
2404 blkif_free(info, 0);
2405 break;
2406 }
2407 }
2408
2409 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2410 physical_sector_size);
2411 if (err) {
2412 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2413 info->xbdev->otherend);
2414 goto fail;
2415 }
2416
2417 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2418
2419 /* Kick pending requests. */
2420 info->connected = BLKIF_STATE_CONNECTED;
2421 for (i = 0; i < info->nr_rings; i++)
2422 kick_pending_request_queues(&info->rinfo[i]);
2423
2424 device_add_disk(&info->xbdev->dev, info->gd, NULL);
2425
2426 info->is_ready = 1;
2427 return;
2428
2429fail:
2430 blkif_free(info, 0);
2431 return;
2432}
2433
2434/**
2435 * Callback received when the backend's state changes.
2436 */
2437static void blkback_changed(struct xenbus_device *dev,
2438 enum xenbus_state backend_state)
2439{
2440 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2441
2442 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2443
2444 switch (backend_state) {
2445 case XenbusStateInitWait:
2446 if (dev->state != XenbusStateInitialising)
2447 break;
2448 if (talk_to_blkback(dev, info))
2449 break;
2450 case XenbusStateInitialising:
2451 case XenbusStateInitialised:
2452 case XenbusStateReconfiguring:
2453 case XenbusStateReconfigured:
2454 case XenbusStateUnknown:
2455 break;
2456
2457 case XenbusStateConnected:
2458 /*
2459 * talk_to_blkback sets state to XenbusStateInitialised
2460 * and blkfront_connect sets it to XenbusStateConnected
2461 * (if connection went OK).
2462 *
2463 * If the backend (or toolstack) decides to poke at backend
2464 * state (and re-trigger the watch by setting the state repeatedly
2465 * to XenbusStateConnected (4)) we need to deal with this.
2466 * This is allowed as this is used to communicate to the guest
2467 * that the size of disk has changed!
2468 */
2469 if ((dev->state != XenbusStateInitialised) &&
2470 (dev->state != XenbusStateConnected)) {
2471 if (talk_to_blkback(dev, info))
2472 break;
2473 }
2474
2475 blkfront_connect(info);
2476 break;
2477
2478 case XenbusStateClosed:
2479 if (dev->state == XenbusStateClosed)
2480 break;
2481 /* fall through */
2482 case XenbusStateClosing:
2483 if (info)
2484 blkfront_closing(info);
2485 break;
2486 }
2487}
2488
2489static int blkfront_remove(struct xenbus_device *xbdev)
2490{
2491 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2492 struct block_device *bdev = NULL;
2493 struct gendisk *disk;
2494
2495 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2496
2497 if (!info)
2498 return 0;
2499
2500 blkif_free(info, 0);
2501
2502 mutex_lock(&info->mutex);
2503
2504 disk = info->gd;
2505 if (disk)
2506 bdev = bdget_disk(disk, 0);
2507
2508 info->xbdev = NULL;
2509 mutex_unlock(&info->mutex);
2510
2511 if (!bdev) {
2512 mutex_lock(&blkfront_mutex);
2513 free_info(info);
2514 mutex_unlock(&blkfront_mutex);
2515 return 0;
2516 }
2517
2518 /*
2519 * The xbdev was removed before we reached the Closed
2520 * state. See if it's safe to remove the disk. If the bdev
2521 * isn't closed yet, we let release take care of it.
2522 */
2523
2524 mutex_lock(&bdev->bd_mutex);
2525 info = disk->private_data;
2526
2527 dev_warn(disk_to_dev(disk),
2528 "%s was hot-unplugged, %d stale handles\n",
2529 xbdev->nodename, bdev->bd_openers);
2530
2531 if (info && !bdev->bd_openers) {
2532 xlvbd_release_gendisk(info);
2533 disk->private_data = NULL;
2534 mutex_lock(&blkfront_mutex);
2535 free_info(info);
2536 mutex_unlock(&blkfront_mutex);
2537 }
2538
2539 mutex_unlock(&bdev->bd_mutex);
2540 bdput(bdev);
2541
2542 return 0;
2543}
2544
2545static int blkfront_is_ready(struct xenbus_device *dev)
2546{
2547 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2548
2549 return info->is_ready && info->xbdev;
2550}
2551
2552static int blkif_open(struct block_device *bdev, fmode_t mode)
2553{
2554 struct gendisk *disk = bdev->bd_disk;
2555 struct blkfront_info *info;
2556 int err = 0;
2557
2558 mutex_lock(&blkfront_mutex);
2559
2560 info = disk->private_data;
2561 if (!info) {
2562 /* xbdev gone */
2563 err = -ERESTARTSYS;
2564 goto out;
2565 }
2566
2567 mutex_lock(&info->mutex);
2568
2569 if (!info->gd)
2570 /* xbdev is closed */
2571 err = -ERESTARTSYS;
2572
2573 mutex_unlock(&info->mutex);
2574
2575out:
2576 mutex_unlock(&blkfront_mutex);
2577 return err;
2578}
2579
2580static void blkif_release(struct gendisk *disk, fmode_t mode)
2581{
2582 struct blkfront_info *info = disk->private_data;
2583 struct block_device *bdev;
2584 struct xenbus_device *xbdev;
2585
2586 mutex_lock(&blkfront_mutex);
2587
2588 bdev = bdget_disk(disk, 0);
2589
2590 if (!bdev) {
2591 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2592 goto out_mutex;
2593 }
2594 if (bdev->bd_openers)
2595 goto out;
2596
2597 /*
2598 * Check if we have been instructed to close. We will have
2599 * deferred this request, because the bdev was still open.
2600 */
2601
2602 mutex_lock(&info->mutex);
2603 xbdev = info->xbdev;
2604
2605 if (xbdev && xbdev->state == XenbusStateClosing) {
2606 /* pending switch to state closed */
2607 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2608 xlvbd_release_gendisk(info);
2609 xenbus_frontend_closed(info->xbdev);
2610 }
2611
2612 mutex_unlock(&info->mutex);
2613
2614 if (!xbdev) {
2615 /* sudden device removal */
2616 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2617 xlvbd_release_gendisk(info);
2618 disk->private_data = NULL;
2619 free_info(info);
2620 }
2621
2622out:
2623 bdput(bdev);
2624out_mutex:
2625 mutex_unlock(&blkfront_mutex);
2626}
2627
2628static const struct block_device_operations xlvbd_block_fops =
2629{
2630 .owner = THIS_MODULE,
2631 .open = blkif_open,
2632 .release = blkif_release,
2633 .getgeo = blkif_getgeo,
2634 .ioctl = blkif_ioctl,
2635};
2636
2637
2638static const struct xenbus_device_id blkfront_ids[] = {
2639 { "vbd" },
2640 { "" }
2641};
2642
2643static struct xenbus_driver blkfront_driver = {
2644 .ids = blkfront_ids,
2645 .probe = blkfront_probe,
2646 .remove = blkfront_remove,
2647 .resume = blkfront_resume,
2648 .otherend_changed = blkback_changed,
2649 .is_ready = blkfront_is_ready,
2650};
2651
2652static void purge_persistent_grants(struct blkfront_info *info)
2653{
2654 unsigned int i;
2655 unsigned long flags;
2656
2657 for (i = 0; i < info->nr_rings; i++) {
2658 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2659 struct grant *gnt_list_entry, *tmp;
2660
2661 spin_lock_irqsave(&rinfo->ring_lock, flags);
2662
2663 if (rinfo->persistent_gnts_c == 0) {
2664 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2665 continue;
2666 }
2667
2668 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2669 node) {
2670 if (gnt_list_entry->gref == GRANT_INVALID_REF ||
2671 gnttab_query_foreign_access(gnt_list_entry->gref))
2672 continue;
2673
2674 list_del(&gnt_list_entry->node);
2675 gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
2676 rinfo->persistent_gnts_c--;
2677 gnt_list_entry->gref = GRANT_INVALID_REF;
2678 list_add_tail(&gnt_list_entry->node, &rinfo->grants);
2679 }
2680
2681 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2682 }
2683}
2684
2685static void blkfront_delay_work(struct work_struct *work)
2686{
2687 struct blkfront_info *info;
2688 bool need_schedule_work = false;
2689
2690 mutex_lock(&blkfront_mutex);
2691
2692 list_for_each_entry(info, &info_list, info_list) {
2693 if (info->feature_persistent) {
2694 need_schedule_work = true;
2695 mutex_lock(&info->mutex);
2696 purge_persistent_grants(info);
2697 mutex_unlock(&info->mutex);
2698 }
2699 }
2700
2701 if (need_schedule_work)
2702 schedule_delayed_work(&blkfront_work, HZ * 10);
2703
2704 mutex_unlock(&blkfront_mutex);
2705}
2706
2707static int __init xlblk_init(void)
2708{
2709 int ret;
2710 int nr_cpus = num_online_cpus();
2711
2712 if (!xen_domain())
2713 return -ENODEV;
2714
2715 if (!xen_has_pv_disk_devices())
2716 return -ENODEV;
2717
2718 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2719 pr_warn("xen_blk: can't get major %d with name %s\n",
2720 XENVBD_MAJOR, DEV_NAME);
2721 return -ENODEV;
2722 }
2723
2724 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2725 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2726
2727 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2728 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2729 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2730 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2731 }
2732
2733 if (xen_blkif_max_queues > nr_cpus) {
2734 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2735 xen_blkif_max_queues, nr_cpus);
2736 xen_blkif_max_queues = nr_cpus;
2737 }
2738
2739 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2740
2741 ret = xenbus_register_frontend(&blkfront_driver);
2742 if (ret) {
2743 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2744 return ret;
2745 }
2746
2747 return 0;
2748}
2749module_init(xlblk_init);
2750
2751
2752static void __exit xlblk_exit(void)
2753{
2754 cancel_delayed_work_sync(&blkfront_work);
2755
2756 xenbus_unregister_driver(&blkfront_driver);
2757 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2758 kfree(minors);
2759}
2760module_exit(xlblk_exit);
2761
2762MODULE_DESCRIPTION("Xen virtual block device frontend");
2763MODULE_LICENSE("GPL");
2764MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2765MODULE_ALIAS("xen:vbd");
2766MODULE_ALIAS("xenblk");