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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/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#include <linux/bitmap.h>
47#include <linux/list.h>
48
49#include <xen/xen.h>
50#include <xen/xenbus.h>
51#include <xen/grant_table.h>
52#include <xen/events.h>
53#include <xen/page.h>
54#include <xen/platform_pci.h>
55
56#include <xen/interface/grant_table.h>
57#include <xen/interface/io/blkif.h>
58#include <xen/interface/io/protocols.h>
59
60#include <asm/xen/hypervisor.h>
61
62enum blkif_state {
63 BLKIF_STATE_DISCONNECTED,
64 BLKIF_STATE_CONNECTED,
65 BLKIF_STATE_SUSPENDED,
66};
67
68struct grant {
69 grant_ref_t gref;
70 unsigned long pfn;
71 struct list_head node;
72};
73
74struct blk_shadow {
75 struct blkif_request req;
76 struct request *request;
77 struct grant **grants_used;
78 struct grant **indirect_grants;
79 struct scatterlist *sg;
80};
81
82struct split_bio {
83 struct bio *bio;
84 atomic_t pending;
85 int err;
86};
87
88static DEFINE_MUTEX(blkfront_mutex);
89static const struct block_device_operations xlvbd_block_fops;
90
91/*
92 * Maximum number of segments in indirect requests, the actual value used by
93 * the frontend driver is the minimum of this value and the value provided
94 * by the backend driver.
95 */
96
97static unsigned int xen_blkif_max_segments = 32;
98module_param_named(max, xen_blkif_max_segments, int, S_IRUGO);
99MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)");
100
101#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
102
103/*
104 * We have one of these per vbd, whether ide, scsi or 'other'. They
105 * hang in private_data off the gendisk structure. We may end up
106 * putting all kinds of interesting stuff here :-)
107 */
108struct blkfront_info
109{
110 spinlock_t io_lock;
111 struct mutex mutex;
112 struct xenbus_device *xbdev;
113 struct gendisk *gd;
114 int vdevice;
115 blkif_vdev_t handle;
116 enum blkif_state connected;
117 int ring_ref;
118 struct blkif_front_ring ring;
119 unsigned int evtchn, irq;
120 struct request_queue *rq;
121 struct work_struct work;
122 struct gnttab_free_callback callback;
123 struct blk_shadow shadow[BLK_RING_SIZE];
124 struct list_head grants;
125 struct list_head indirect_pages;
126 unsigned int persistent_gnts_c;
127 unsigned long shadow_free;
128 unsigned int feature_flush;
129 unsigned int flush_op;
130 unsigned int feature_discard:1;
131 unsigned int feature_secdiscard:1;
132 unsigned int discard_granularity;
133 unsigned int discard_alignment;
134 unsigned int feature_persistent:1;
135 unsigned int max_indirect_segments;
136 int is_ready;
137};
138
139static unsigned int nr_minors;
140static unsigned long *minors;
141static DEFINE_SPINLOCK(minor_lock);
142
143#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
144 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
145#define GRANT_INVALID_REF 0
146
147#define PARTS_PER_DISK 16
148#define PARTS_PER_EXT_DISK 256
149
150#define BLKIF_MAJOR(dev) ((dev)>>8)
151#define BLKIF_MINOR(dev) ((dev) & 0xff)
152
153#define EXT_SHIFT 28
154#define EXTENDED (1<<EXT_SHIFT)
155#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
156#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
157#define EMULATED_HD_DISK_MINOR_OFFSET (0)
158#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
159#define EMULATED_SD_DISK_MINOR_OFFSET (0)
160#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
161
162#define DEV_NAME "xvd" /* name in /dev */
163
164#define SEGS_PER_INDIRECT_FRAME \
165 (PAGE_SIZE/sizeof(struct blkif_request_segment))
166#define INDIRECT_GREFS(_segs) \
167 ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
168
169static int blkfront_setup_indirect(struct blkfront_info *info);
170
171static int get_id_from_freelist(struct blkfront_info *info)
172{
173 unsigned long free = info->shadow_free;
174 BUG_ON(free >= BLK_RING_SIZE);
175 info->shadow_free = info->shadow[free].req.u.rw.id;
176 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
177 return free;
178}
179
180static int add_id_to_freelist(struct blkfront_info *info,
181 unsigned long id)
182{
183 if (info->shadow[id].req.u.rw.id != id)
184 return -EINVAL;
185 if (info->shadow[id].request == NULL)
186 return -EINVAL;
187 info->shadow[id].req.u.rw.id = info->shadow_free;
188 info->shadow[id].request = NULL;
189 info->shadow_free = id;
190 return 0;
191}
192
193static int fill_grant_buffer(struct blkfront_info *info, int num)
194{
195 struct page *granted_page;
196 struct grant *gnt_list_entry, *n;
197 int i = 0;
198
199 while(i < num) {
200 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
201 if (!gnt_list_entry)
202 goto out_of_memory;
203
204 if (info->feature_persistent) {
205 granted_page = alloc_page(GFP_NOIO);
206 if (!granted_page) {
207 kfree(gnt_list_entry);
208 goto out_of_memory;
209 }
210 gnt_list_entry->pfn = page_to_pfn(granted_page);
211 }
212
213 gnt_list_entry->gref = GRANT_INVALID_REF;
214 list_add(&gnt_list_entry->node, &info->grants);
215 i++;
216 }
217
218 return 0;
219
220out_of_memory:
221 list_for_each_entry_safe(gnt_list_entry, n,
222 &info->grants, node) {
223 list_del(&gnt_list_entry->node);
224 if (info->feature_persistent)
225 __free_page(pfn_to_page(gnt_list_entry->pfn));
226 kfree(gnt_list_entry);
227 i--;
228 }
229 BUG_ON(i != 0);
230 return -ENOMEM;
231}
232
233static struct grant *get_grant(grant_ref_t *gref_head,
234 unsigned long pfn,
235 struct blkfront_info *info)
236{
237 struct grant *gnt_list_entry;
238 unsigned long buffer_mfn;
239
240 BUG_ON(list_empty(&info->grants));
241 gnt_list_entry = list_first_entry(&info->grants, struct grant,
242 node);
243 list_del(&gnt_list_entry->node);
244
245 if (gnt_list_entry->gref != GRANT_INVALID_REF) {
246 info->persistent_gnts_c--;
247 return gnt_list_entry;
248 }
249
250 /* Assign a gref to this page */
251 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
252 BUG_ON(gnt_list_entry->gref == -ENOSPC);
253 if (!info->feature_persistent) {
254 BUG_ON(!pfn);
255 gnt_list_entry->pfn = pfn;
256 }
257 buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
258 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
259 info->xbdev->otherend_id,
260 buffer_mfn, 0);
261 return gnt_list_entry;
262}
263
264static const char *op_name(int op)
265{
266 static const char *const names[] = {
267 [BLKIF_OP_READ] = "read",
268 [BLKIF_OP_WRITE] = "write",
269 [BLKIF_OP_WRITE_BARRIER] = "barrier",
270 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
271 [BLKIF_OP_DISCARD] = "discard" };
272
273 if (op < 0 || op >= ARRAY_SIZE(names))
274 return "unknown";
275
276 if (!names[op])
277 return "reserved";
278
279 return names[op];
280}
281static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
282{
283 unsigned int end = minor + nr;
284 int rc;
285
286 if (end > nr_minors) {
287 unsigned long *bitmap, *old;
288
289 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
290 GFP_KERNEL);
291 if (bitmap == NULL)
292 return -ENOMEM;
293
294 spin_lock(&minor_lock);
295 if (end > nr_minors) {
296 old = minors;
297 memcpy(bitmap, minors,
298 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
299 minors = bitmap;
300 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
301 } else
302 old = bitmap;
303 spin_unlock(&minor_lock);
304 kfree(old);
305 }
306
307 spin_lock(&minor_lock);
308 if (find_next_bit(minors, end, minor) >= end) {
309 bitmap_set(minors, minor, nr);
310 rc = 0;
311 } else
312 rc = -EBUSY;
313 spin_unlock(&minor_lock);
314
315 return rc;
316}
317
318static void xlbd_release_minors(unsigned int minor, unsigned int nr)
319{
320 unsigned int end = minor + nr;
321
322 BUG_ON(end > nr_minors);
323 spin_lock(&minor_lock);
324 bitmap_clear(minors, minor, nr);
325 spin_unlock(&minor_lock);
326}
327
328static void blkif_restart_queue_callback(void *arg)
329{
330 struct blkfront_info *info = (struct blkfront_info *)arg;
331 schedule_work(&info->work);
332}
333
334static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
335{
336 /* We don't have real geometry info, but let's at least return
337 values consistent with the size of the device */
338 sector_t nsect = get_capacity(bd->bd_disk);
339 sector_t cylinders = nsect;
340
341 hg->heads = 0xff;
342 hg->sectors = 0x3f;
343 sector_div(cylinders, hg->heads * hg->sectors);
344 hg->cylinders = cylinders;
345 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
346 hg->cylinders = 0xffff;
347 return 0;
348}
349
350static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
351 unsigned command, unsigned long argument)
352{
353 struct blkfront_info *info = bdev->bd_disk->private_data;
354 int i;
355
356 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
357 command, (long)argument);
358
359 switch (command) {
360 case CDROMMULTISESSION:
361 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
362 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
363 if (put_user(0, (char __user *)(argument + i)))
364 return -EFAULT;
365 return 0;
366
367 case CDROM_GET_CAPABILITY: {
368 struct gendisk *gd = info->gd;
369 if (gd->flags & GENHD_FL_CD)
370 return 0;
371 return -EINVAL;
372 }
373
374 default:
375 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
376 command);*/
377 return -EINVAL; /* same return as native Linux */
378 }
379
380 return 0;
381}
382
383/*
384 * Generate a Xen blkfront IO request from a blk layer request. Reads
385 * and writes are handled as expected.
386 *
387 * @req: a request struct
388 */
389static int blkif_queue_request(struct request *req)
390{
391 struct blkfront_info *info = req->rq_disk->private_data;
392 struct blkif_request *ring_req;
393 unsigned long id;
394 unsigned int fsect, lsect;
395 int i, ref, n;
396 struct blkif_request_segment *segments = NULL;
397
398 /*
399 * Used to store if we are able to queue the request by just using
400 * existing persistent grants, or if we have to get new grants,
401 * as there are not sufficiently many free.
402 */
403 bool new_persistent_gnts;
404 grant_ref_t gref_head;
405 struct grant *gnt_list_entry = NULL;
406 struct scatterlist *sg;
407 int nseg, max_grefs;
408
409 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
410 return 1;
411
412 max_grefs = req->nr_phys_segments;
413 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
414 /*
415 * If we are using indirect segments we need to account
416 * for the indirect grefs used in the request.
417 */
418 max_grefs += INDIRECT_GREFS(req->nr_phys_segments);
419
420 /* Check if we have enough grants to allocate a requests */
421 if (info->persistent_gnts_c < max_grefs) {
422 new_persistent_gnts = 1;
423 if (gnttab_alloc_grant_references(
424 max_grefs - info->persistent_gnts_c,
425 &gref_head) < 0) {
426 gnttab_request_free_callback(
427 &info->callback,
428 blkif_restart_queue_callback,
429 info,
430 max_grefs);
431 return 1;
432 }
433 } else
434 new_persistent_gnts = 0;
435
436 /* Fill out a communications ring structure. */
437 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
438 id = get_id_from_freelist(info);
439 info->shadow[id].request = req;
440
441 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
442 ring_req->operation = BLKIF_OP_DISCARD;
443 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
444 ring_req->u.discard.id = id;
445 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
446 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
447 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
448 else
449 ring_req->u.discard.flag = 0;
450 } else {
451 BUG_ON(info->max_indirect_segments == 0 &&
452 req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
453 BUG_ON(info->max_indirect_segments &&
454 req->nr_phys_segments > info->max_indirect_segments);
455 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
456 ring_req->u.rw.id = id;
457 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
458 /*
459 * The indirect operation can only be a BLKIF_OP_READ or
460 * BLKIF_OP_WRITE
461 */
462 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
463 ring_req->operation = BLKIF_OP_INDIRECT;
464 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
465 BLKIF_OP_WRITE : BLKIF_OP_READ;
466 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
467 ring_req->u.indirect.handle = info->handle;
468 ring_req->u.indirect.nr_segments = nseg;
469 } else {
470 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
471 ring_req->u.rw.handle = info->handle;
472 ring_req->operation = rq_data_dir(req) ?
473 BLKIF_OP_WRITE : BLKIF_OP_READ;
474 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
475 /*
476 * Ideally we can do an unordered flush-to-disk. In case the
477 * backend onlysupports barriers, use that. A barrier request
478 * a superset of FUA, so we can implement it the same
479 * way. (It's also a FLUSH+FUA, since it is
480 * guaranteed ordered WRT previous writes.)
481 */
482 ring_req->operation = info->flush_op;
483 }
484 ring_req->u.rw.nr_segments = nseg;
485 }
486 for_each_sg(info->shadow[id].sg, sg, nseg, i) {
487 fsect = sg->offset >> 9;
488 lsect = fsect + (sg->length >> 9) - 1;
489
490 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
491 (i % SEGS_PER_INDIRECT_FRAME == 0)) {
492 unsigned long uninitialized_var(pfn);
493
494 if (segments)
495 kunmap_atomic(segments);
496
497 n = i / SEGS_PER_INDIRECT_FRAME;
498 if (!info->feature_persistent) {
499 struct page *indirect_page;
500
501 /* Fetch a pre-allocated page to use for indirect grefs */
502 BUG_ON(list_empty(&info->indirect_pages));
503 indirect_page = list_first_entry(&info->indirect_pages,
504 struct page, lru);
505 list_del(&indirect_page->lru);
506 pfn = page_to_pfn(indirect_page);
507 }
508 gnt_list_entry = get_grant(&gref_head, pfn, info);
509 info->shadow[id].indirect_grants[n] = gnt_list_entry;
510 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
511 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
512 }
513
514 gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
515 ref = gnt_list_entry->gref;
516
517 info->shadow[id].grants_used[i] = gnt_list_entry;
518
519 if (rq_data_dir(req) && info->feature_persistent) {
520 char *bvec_data;
521 void *shared_data;
522
523 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
524
525 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
526 bvec_data = kmap_atomic(sg_page(sg));
527
528 /*
529 * this does not wipe data stored outside the
530 * range sg->offset..sg->offset+sg->length.
531 * Therefore, blkback *could* see data from
532 * previous requests. This is OK as long as
533 * persistent grants are shared with just one
534 * domain. It may need refactoring if this
535 * changes
536 */
537 memcpy(shared_data + sg->offset,
538 bvec_data + sg->offset,
539 sg->length);
540
541 kunmap_atomic(bvec_data);
542 kunmap_atomic(shared_data);
543 }
544 if (ring_req->operation != BLKIF_OP_INDIRECT) {
545 ring_req->u.rw.seg[i] =
546 (struct blkif_request_segment) {
547 .gref = ref,
548 .first_sect = fsect,
549 .last_sect = lsect };
550 } else {
551 n = i % SEGS_PER_INDIRECT_FRAME;
552 segments[n] =
553 (struct blkif_request_segment) {
554 .gref = ref,
555 .first_sect = fsect,
556 .last_sect = lsect };
557 }
558 }
559 if (segments)
560 kunmap_atomic(segments);
561 }
562
563 info->ring.req_prod_pvt++;
564
565 /* Keep a private copy so we can reissue requests when recovering. */
566 info->shadow[id].req = *ring_req;
567
568 if (new_persistent_gnts)
569 gnttab_free_grant_references(gref_head);
570
571 return 0;
572}
573
574
575static inline void flush_requests(struct blkfront_info *info)
576{
577 int notify;
578
579 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
580
581 if (notify)
582 notify_remote_via_irq(info->irq);
583}
584
585/*
586 * do_blkif_request
587 * read a block; request is in a request queue
588 */
589static void do_blkif_request(struct request_queue *rq)
590{
591 struct blkfront_info *info = NULL;
592 struct request *req;
593 int queued;
594
595 pr_debug("Entered do_blkif_request\n");
596
597 queued = 0;
598
599 while ((req = blk_peek_request(rq)) != NULL) {
600 info = req->rq_disk->private_data;
601
602 if (RING_FULL(&info->ring))
603 goto wait;
604
605 blk_start_request(req);
606
607 if ((req->cmd_type != REQ_TYPE_FS) ||
608 ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) &&
609 !info->flush_op)) {
610 __blk_end_request_all(req, -EIO);
611 continue;
612 }
613
614 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
615 "(%u/%u) buffer:%p [%s]\n",
616 req, req->cmd, (unsigned long)blk_rq_pos(req),
617 blk_rq_cur_sectors(req), blk_rq_sectors(req),
618 req->buffer, rq_data_dir(req) ? "write" : "read");
619
620 if (blkif_queue_request(req)) {
621 blk_requeue_request(rq, req);
622wait:
623 /* Avoid pointless unplugs. */
624 blk_stop_queue(rq);
625 break;
626 }
627
628 queued++;
629 }
630
631 if (queued != 0)
632 flush_requests(info);
633}
634
635static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
636 unsigned int physical_sector_size,
637 unsigned int segments)
638{
639 struct request_queue *rq;
640 struct blkfront_info *info = gd->private_data;
641
642 rq = blk_init_queue(do_blkif_request, &info->io_lock);
643 if (rq == NULL)
644 return -1;
645
646 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
647
648 if (info->feature_discard) {
649 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
650 blk_queue_max_discard_sectors(rq, get_capacity(gd));
651 rq->limits.discard_granularity = info->discard_granularity;
652 rq->limits.discard_alignment = info->discard_alignment;
653 if (info->feature_secdiscard)
654 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
655 }
656
657 /* Hard sector size and max sectors impersonate the equiv. hardware. */
658 blk_queue_logical_block_size(rq, sector_size);
659 blk_queue_physical_block_size(rq, physical_sector_size);
660 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512);
661
662 /* Each segment in a request is up to an aligned page in size. */
663 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
664 blk_queue_max_segment_size(rq, PAGE_SIZE);
665
666 /* Ensure a merged request will fit in a single I/O ring slot. */
667 blk_queue_max_segments(rq, segments);
668
669 /* Make sure buffer addresses are sector-aligned. */
670 blk_queue_dma_alignment(rq, 511);
671
672 /* Make sure we don't use bounce buffers. */
673 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
674
675 gd->queue = rq;
676
677 return 0;
678}
679
680
681static void xlvbd_flush(struct blkfront_info *info)
682{
683 blk_queue_flush(info->rq, info->feature_flush);
684 printk(KERN_INFO "blkfront: %s: %s: %s %s %s %s %s\n",
685 info->gd->disk_name,
686 info->flush_op == BLKIF_OP_WRITE_BARRIER ?
687 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
688 "flush diskcache" : "barrier or flush"),
689 info->feature_flush ? "enabled;" : "disabled;",
690 "persistent grants:",
691 info->feature_persistent ? "enabled;" : "disabled;",
692 "indirect descriptors:",
693 info->max_indirect_segments ? "enabled;" : "disabled;");
694}
695
696static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
697{
698 int major;
699 major = BLKIF_MAJOR(vdevice);
700 *minor = BLKIF_MINOR(vdevice);
701 switch (major) {
702 case XEN_IDE0_MAJOR:
703 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
704 *minor = ((*minor / 64) * PARTS_PER_DISK) +
705 EMULATED_HD_DISK_MINOR_OFFSET;
706 break;
707 case XEN_IDE1_MAJOR:
708 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
709 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
710 EMULATED_HD_DISK_MINOR_OFFSET;
711 break;
712 case XEN_SCSI_DISK0_MAJOR:
713 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
714 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
715 break;
716 case XEN_SCSI_DISK1_MAJOR:
717 case XEN_SCSI_DISK2_MAJOR:
718 case XEN_SCSI_DISK3_MAJOR:
719 case XEN_SCSI_DISK4_MAJOR:
720 case XEN_SCSI_DISK5_MAJOR:
721 case XEN_SCSI_DISK6_MAJOR:
722 case XEN_SCSI_DISK7_MAJOR:
723 *offset = (*minor / PARTS_PER_DISK) +
724 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
725 EMULATED_SD_DISK_NAME_OFFSET;
726 *minor = *minor +
727 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
728 EMULATED_SD_DISK_MINOR_OFFSET;
729 break;
730 case XEN_SCSI_DISK8_MAJOR:
731 case XEN_SCSI_DISK9_MAJOR:
732 case XEN_SCSI_DISK10_MAJOR:
733 case XEN_SCSI_DISK11_MAJOR:
734 case XEN_SCSI_DISK12_MAJOR:
735 case XEN_SCSI_DISK13_MAJOR:
736 case XEN_SCSI_DISK14_MAJOR:
737 case XEN_SCSI_DISK15_MAJOR:
738 *offset = (*minor / PARTS_PER_DISK) +
739 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
740 EMULATED_SD_DISK_NAME_OFFSET;
741 *minor = *minor +
742 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
743 EMULATED_SD_DISK_MINOR_OFFSET;
744 break;
745 case XENVBD_MAJOR:
746 *offset = *minor / PARTS_PER_DISK;
747 break;
748 default:
749 printk(KERN_WARNING "blkfront: your disk configuration is "
750 "incorrect, please use an xvd device instead\n");
751 return -ENODEV;
752 }
753 return 0;
754}
755
756static char *encode_disk_name(char *ptr, unsigned int n)
757{
758 if (n >= 26)
759 ptr = encode_disk_name(ptr, n / 26 - 1);
760 *ptr = 'a' + n % 26;
761 return ptr + 1;
762}
763
764static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
765 struct blkfront_info *info,
766 u16 vdisk_info, u16 sector_size,
767 unsigned int physical_sector_size)
768{
769 struct gendisk *gd;
770 int nr_minors = 1;
771 int err;
772 unsigned int offset;
773 int minor;
774 int nr_parts;
775 char *ptr;
776
777 BUG_ON(info->gd != NULL);
778 BUG_ON(info->rq != NULL);
779
780 if ((info->vdevice>>EXT_SHIFT) > 1) {
781 /* this is above the extended range; something is wrong */
782 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
783 return -ENODEV;
784 }
785
786 if (!VDEV_IS_EXTENDED(info->vdevice)) {
787 err = xen_translate_vdev(info->vdevice, &minor, &offset);
788 if (err)
789 return err;
790 nr_parts = PARTS_PER_DISK;
791 } else {
792 minor = BLKIF_MINOR_EXT(info->vdevice);
793 nr_parts = PARTS_PER_EXT_DISK;
794 offset = minor / nr_parts;
795 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
796 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
797 "emulated IDE disks,\n\t choose an xvd device name"
798 "from xvde on\n", info->vdevice);
799 }
800 if (minor >> MINORBITS) {
801 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
802 info->vdevice, minor);
803 return -ENODEV;
804 }
805
806 if ((minor % nr_parts) == 0)
807 nr_minors = nr_parts;
808
809 err = xlbd_reserve_minors(minor, nr_minors);
810 if (err)
811 goto out;
812 err = -ENODEV;
813
814 gd = alloc_disk(nr_minors);
815 if (gd == NULL)
816 goto release;
817
818 strcpy(gd->disk_name, DEV_NAME);
819 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
820 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
821 if (nr_minors > 1)
822 *ptr = 0;
823 else
824 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
825 "%d", minor & (nr_parts - 1));
826
827 gd->major = XENVBD_MAJOR;
828 gd->first_minor = minor;
829 gd->fops = &xlvbd_block_fops;
830 gd->private_data = info;
831 gd->driverfs_dev = &(info->xbdev->dev);
832 set_capacity(gd, capacity);
833
834 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
835 info->max_indirect_segments ? :
836 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
837 del_gendisk(gd);
838 goto release;
839 }
840
841 info->rq = gd->queue;
842 info->gd = gd;
843
844 xlvbd_flush(info);
845
846 if (vdisk_info & VDISK_READONLY)
847 set_disk_ro(gd, 1);
848
849 if (vdisk_info & VDISK_REMOVABLE)
850 gd->flags |= GENHD_FL_REMOVABLE;
851
852 if (vdisk_info & VDISK_CDROM)
853 gd->flags |= GENHD_FL_CD;
854
855 return 0;
856
857 release:
858 xlbd_release_minors(minor, nr_minors);
859 out:
860 return err;
861}
862
863static void xlvbd_release_gendisk(struct blkfront_info *info)
864{
865 unsigned int minor, nr_minors;
866 unsigned long flags;
867
868 if (info->rq == NULL)
869 return;
870
871 spin_lock_irqsave(&info->io_lock, flags);
872
873 /* No more blkif_request(). */
874 blk_stop_queue(info->rq);
875
876 /* No more gnttab callback work. */
877 gnttab_cancel_free_callback(&info->callback);
878 spin_unlock_irqrestore(&info->io_lock, flags);
879
880 /* Flush gnttab callback work. Must be done with no locks held. */
881 flush_work(&info->work);
882
883 del_gendisk(info->gd);
884
885 minor = info->gd->first_minor;
886 nr_minors = info->gd->minors;
887 xlbd_release_minors(minor, nr_minors);
888
889 blk_cleanup_queue(info->rq);
890 info->rq = NULL;
891
892 put_disk(info->gd);
893 info->gd = NULL;
894}
895
896static void kick_pending_request_queues(struct blkfront_info *info)
897{
898 if (!RING_FULL(&info->ring)) {
899 /* Re-enable calldowns. */
900 blk_start_queue(info->rq);
901 /* Kick things off immediately. */
902 do_blkif_request(info->rq);
903 }
904}
905
906static void blkif_restart_queue(struct work_struct *work)
907{
908 struct blkfront_info *info = container_of(work, struct blkfront_info, work);
909
910 spin_lock_irq(&info->io_lock);
911 if (info->connected == BLKIF_STATE_CONNECTED)
912 kick_pending_request_queues(info);
913 spin_unlock_irq(&info->io_lock);
914}
915
916static void blkif_free(struct blkfront_info *info, int suspend)
917{
918 struct grant *persistent_gnt;
919 struct grant *n;
920 int i, j, segs;
921
922 /* Prevent new requests being issued until we fix things up. */
923 spin_lock_irq(&info->io_lock);
924 info->connected = suspend ?
925 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
926 /* No more blkif_request(). */
927 if (info->rq)
928 blk_stop_queue(info->rq);
929
930 /* Remove all persistent grants */
931 if (!list_empty(&info->grants)) {
932 list_for_each_entry_safe(persistent_gnt, n,
933 &info->grants, node) {
934 list_del(&persistent_gnt->node);
935 if (persistent_gnt->gref != GRANT_INVALID_REF) {
936 gnttab_end_foreign_access(persistent_gnt->gref,
937 0, 0UL);
938 info->persistent_gnts_c--;
939 }
940 if (info->feature_persistent)
941 __free_page(pfn_to_page(persistent_gnt->pfn));
942 kfree(persistent_gnt);
943 }
944 }
945 BUG_ON(info->persistent_gnts_c != 0);
946
947 /*
948 * Remove indirect pages, this only happens when using indirect
949 * descriptors but not persistent grants
950 */
951 if (!list_empty(&info->indirect_pages)) {
952 struct page *indirect_page, *n;
953
954 BUG_ON(info->feature_persistent);
955 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
956 list_del(&indirect_page->lru);
957 __free_page(indirect_page);
958 }
959 }
960
961 for (i = 0; i < BLK_RING_SIZE; i++) {
962 /*
963 * Clear persistent grants present in requests already
964 * on the shared ring
965 */
966 if (!info->shadow[i].request)
967 goto free_shadow;
968
969 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
970 info->shadow[i].req.u.indirect.nr_segments :
971 info->shadow[i].req.u.rw.nr_segments;
972 for (j = 0; j < segs; j++) {
973 persistent_gnt = info->shadow[i].grants_used[j];
974 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
975 if (info->feature_persistent)
976 __free_page(pfn_to_page(persistent_gnt->pfn));
977 kfree(persistent_gnt);
978 }
979
980 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT)
981 /*
982 * If this is not an indirect operation don't try to
983 * free indirect segments
984 */
985 goto free_shadow;
986
987 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
988 persistent_gnt = info->shadow[i].indirect_grants[j];
989 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
990 __free_page(pfn_to_page(persistent_gnt->pfn));
991 kfree(persistent_gnt);
992 }
993
994free_shadow:
995 kfree(info->shadow[i].grants_used);
996 info->shadow[i].grants_used = NULL;
997 kfree(info->shadow[i].indirect_grants);
998 info->shadow[i].indirect_grants = NULL;
999 kfree(info->shadow[i].sg);
1000 info->shadow[i].sg = NULL;
1001 }
1002
1003 /* No more gnttab callback work. */
1004 gnttab_cancel_free_callback(&info->callback);
1005 spin_unlock_irq(&info->io_lock);
1006
1007 /* Flush gnttab callback work. Must be done with no locks held. */
1008 flush_work(&info->work);
1009
1010 /* Free resources associated with old device channel. */
1011 if (info->ring_ref != GRANT_INVALID_REF) {
1012 gnttab_end_foreign_access(info->ring_ref, 0,
1013 (unsigned long)info->ring.sring);
1014 info->ring_ref = GRANT_INVALID_REF;
1015 info->ring.sring = NULL;
1016 }
1017 if (info->irq)
1018 unbind_from_irqhandler(info->irq, info);
1019 info->evtchn = info->irq = 0;
1020
1021}
1022
1023static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
1024 struct blkif_response *bret)
1025{
1026 int i = 0;
1027 struct scatterlist *sg;
1028 char *bvec_data;
1029 void *shared_data;
1030 int nseg;
1031
1032 nseg = s->req.operation == BLKIF_OP_INDIRECT ?
1033 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1034
1035 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1036 /*
1037 * Copy the data received from the backend into the bvec.
1038 * Since bv_offset can be different than 0, and bv_len different
1039 * than PAGE_SIZE, we have to keep track of the current offset,
1040 * to be sure we are copying the data from the right shared page.
1041 */
1042 for_each_sg(s->sg, sg, nseg, i) {
1043 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1044 shared_data = kmap_atomic(
1045 pfn_to_page(s->grants_used[i]->pfn));
1046 bvec_data = kmap_atomic(sg_page(sg));
1047 memcpy(bvec_data + sg->offset,
1048 shared_data + sg->offset,
1049 sg->length);
1050 kunmap_atomic(bvec_data);
1051 kunmap_atomic(shared_data);
1052 }
1053 }
1054 /* Add the persistent grant into the list of free grants */
1055 for (i = 0; i < nseg; i++) {
1056 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1057 /*
1058 * If the grant is still mapped by the backend (the
1059 * backend has chosen to make this grant persistent)
1060 * we add it at the head of the list, so it will be
1061 * reused first.
1062 */
1063 if (!info->feature_persistent)
1064 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1065 s->grants_used[i]->gref);
1066 list_add(&s->grants_used[i]->node, &info->grants);
1067 info->persistent_gnts_c++;
1068 } else {
1069 /*
1070 * If the grant is not mapped by the backend we end the
1071 * foreign access and add it to the tail of the list,
1072 * so it will not be picked again unless we run out of
1073 * persistent grants.
1074 */
1075 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1076 s->grants_used[i]->gref = GRANT_INVALID_REF;
1077 list_add_tail(&s->grants_used[i]->node, &info->grants);
1078 }
1079 }
1080 if (s->req.operation == BLKIF_OP_INDIRECT) {
1081 for (i = 0; i < INDIRECT_GREFS(nseg); i++) {
1082 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1083 if (!info->feature_persistent)
1084 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1085 s->indirect_grants[i]->gref);
1086 list_add(&s->indirect_grants[i]->node, &info->grants);
1087 info->persistent_gnts_c++;
1088 } else {
1089 struct page *indirect_page;
1090
1091 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1092 /*
1093 * Add the used indirect page back to the list of
1094 * available pages for indirect grefs.
1095 */
1096 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
1097 list_add(&indirect_page->lru, &info->indirect_pages);
1098 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1099 list_add_tail(&s->indirect_grants[i]->node, &info->grants);
1100 }
1101 }
1102 }
1103}
1104
1105static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1106{
1107 struct request *req;
1108 struct blkif_response *bret;
1109 RING_IDX i, rp;
1110 unsigned long flags;
1111 struct blkfront_info *info = (struct blkfront_info *)dev_id;
1112 int error;
1113
1114 spin_lock_irqsave(&info->io_lock, flags);
1115
1116 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1117 spin_unlock_irqrestore(&info->io_lock, flags);
1118 return IRQ_HANDLED;
1119 }
1120
1121 again:
1122 rp = info->ring.sring->rsp_prod;
1123 rmb(); /* Ensure we see queued responses up to 'rp'. */
1124
1125 for (i = info->ring.rsp_cons; i != rp; i++) {
1126 unsigned long id;
1127
1128 bret = RING_GET_RESPONSE(&info->ring, i);
1129 id = bret->id;
1130 /*
1131 * The backend has messed up and given us an id that we would
1132 * never have given to it (we stamp it up to BLK_RING_SIZE -
1133 * look in get_id_from_freelist.
1134 */
1135 if (id >= BLK_RING_SIZE) {
1136 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1137 info->gd->disk_name, op_name(bret->operation), id);
1138 /* We can't safely get the 'struct request' as
1139 * the id is busted. */
1140 continue;
1141 }
1142 req = info->shadow[id].request;
1143
1144 if (bret->operation != BLKIF_OP_DISCARD)
1145 blkif_completion(&info->shadow[id], info, bret);
1146
1147 if (add_id_to_freelist(info, id)) {
1148 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1149 info->gd->disk_name, op_name(bret->operation), id);
1150 continue;
1151 }
1152
1153 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1154 switch (bret->operation) {
1155 case BLKIF_OP_DISCARD:
1156 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1157 struct request_queue *rq = info->rq;
1158 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1159 info->gd->disk_name, op_name(bret->operation));
1160 error = -EOPNOTSUPP;
1161 info->feature_discard = 0;
1162 info->feature_secdiscard = 0;
1163 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1164 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1165 }
1166 __blk_end_request_all(req, error);
1167 break;
1168 case BLKIF_OP_FLUSH_DISKCACHE:
1169 case BLKIF_OP_WRITE_BARRIER:
1170 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1171 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1172 info->gd->disk_name, op_name(bret->operation));
1173 error = -EOPNOTSUPP;
1174 }
1175 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1176 info->shadow[id].req.u.rw.nr_segments == 0)) {
1177 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1178 info->gd->disk_name, op_name(bret->operation));
1179 error = -EOPNOTSUPP;
1180 }
1181 if (unlikely(error)) {
1182 if (error == -EOPNOTSUPP)
1183 error = 0;
1184 info->feature_flush = 0;
1185 info->flush_op = 0;
1186 xlvbd_flush(info);
1187 }
1188 /* fall through */
1189 case BLKIF_OP_READ:
1190 case BLKIF_OP_WRITE:
1191 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1192 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1193 "request: %x\n", bret->status);
1194
1195 __blk_end_request_all(req, error);
1196 break;
1197 default:
1198 BUG();
1199 }
1200 }
1201
1202 info->ring.rsp_cons = i;
1203
1204 if (i != info->ring.req_prod_pvt) {
1205 int more_to_do;
1206 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
1207 if (more_to_do)
1208 goto again;
1209 } else
1210 info->ring.sring->rsp_event = i + 1;
1211
1212 kick_pending_request_queues(info);
1213
1214 spin_unlock_irqrestore(&info->io_lock, flags);
1215
1216 return IRQ_HANDLED;
1217}
1218
1219
1220static int setup_blkring(struct xenbus_device *dev,
1221 struct blkfront_info *info)
1222{
1223 struct blkif_sring *sring;
1224 int err;
1225
1226 info->ring_ref = GRANT_INVALID_REF;
1227
1228 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
1229 if (!sring) {
1230 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1231 return -ENOMEM;
1232 }
1233 SHARED_RING_INIT(sring);
1234 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
1235
1236 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
1237 if (err < 0) {
1238 free_page((unsigned long)sring);
1239 info->ring.sring = NULL;
1240 goto fail;
1241 }
1242 info->ring_ref = err;
1243
1244 err = xenbus_alloc_evtchn(dev, &info->evtchn);
1245 if (err)
1246 goto fail;
1247
1248 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
1249 "blkif", info);
1250 if (err <= 0) {
1251 xenbus_dev_fatal(dev, err,
1252 "bind_evtchn_to_irqhandler failed");
1253 goto fail;
1254 }
1255 info->irq = err;
1256
1257 return 0;
1258fail:
1259 blkif_free(info, 0);
1260 return err;
1261}
1262
1263
1264/* Common code used when first setting up, and when resuming. */
1265static int talk_to_blkback(struct xenbus_device *dev,
1266 struct blkfront_info *info)
1267{
1268 const char *message = NULL;
1269 struct xenbus_transaction xbt;
1270 int err;
1271
1272 /* Create shared ring, alloc event channel. */
1273 err = setup_blkring(dev, info);
1274 if (err)
1275 goto out;
1276
1277again:
1278 err = xenbus_transaction_start(&xbt);
1279 if (err) {
1280 xenbus_dev_fatal(dev, err, "starting transaction");
1281 goto destroy_blkring;
1282 }
1283
1284 err = xenbus_printf(xbt, dev->nodename,
1285 "ring-ref", "%u", info->ring_ref);
1286 if (err) {
1287 message = "writing ring-ref";
1288 goto abort_transaction;
1289 }
1290 err = xenbus_printf(xbt, dev->nodename,
1291 "event-channel", "%u", info->evtchn);
1292 if (err) {
1293 message = "writing event-channel";
1294 goto abort_transaction;
1295 }
1296 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1297 XEN_IO_PROTO_ABI_NATIVE);
1298 if (err) {
1299 message = "writing protocol";
1300 goto abort_transaction;
1301 }
1302 err = xenbus_printf(xbt, dev->nodename,
1303 "feature-persistent", "%u", 1);
1304 if (err)
1305 dev_warn(&dev->dev,
1306 "writing persistent grants feature to xenbus");
1307
1308 err = xenbus_transaction_end(xbt, 0);
1309 if (err) {
1310 if (err == -EAGAIN)
1311 goto again;
1312 xenbus_dev_fatal(dev, err, "completing transaction");
1313 goto destroy_blkring;
1314 }
1315
1316 xenbus_switch_state(dev, XenbusStateInitialised);
1317
1318 return 0;
1319
1320 abort_transaction:
1321 xenbus_transaction_end(xbt, 1);
1322 if (message)
1323 xenbus_dev_fatal(dev, err, "%s", message);
1324 destroy_blkring:
1325 blkif_free(info, 0);
1326 out:
1327 return err;
1328}
1329
1330/**
1331 * Entry point to this code when a new device is created. Allocate the basic
1332 * structures and the ring buffer for communication with the backend, and
1333 * inform the backend of the appropriate details for those. Switch to
1334 * Initialised state.
1335 */
1336static int blkfront_probe(struct xenbus_device *dev,
1337 const struct xenbus_device_id *id)
1338{
1339 int err, vdevice, i;
1340 struct blkfront_info *info;
1341
1342 /* FIXME: Use dynamic device id if this is not set. */
1343 err = xenbus_scanf(XBT_NIL, dev->nodename,
1344 "virtual-device", "%i", &vdevice);
1345 if (err != 1) {
1346 /* go looking in the extended area instead */
1347 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1348 "%i", &vdevice);
1349 if (err != 1) {
1350 xenbus_dev_fatal(dev, err, "reading virtual-device");
1351 return err;
1352 }
1353 }
1354
1355 if (xen_hvm_domain()) {
1356 char *type;
1357 int len;
1358 /* no unplug has been done: do not hook devices != xen vbds */
1359 if (xen_has_pv_and_legacy_disk_devices()) {
1360 int major;
1361
1362 if (!VDEV_IS_EXTENDED(vdevice))
1363 major = BLKIF_MAJOR(vdevice);
1364 else
1365 major = XENVBD_MAJOR;
1366
1367 if (major != XENVBD_MAJOR) {
1368 printk(KERN_INFO
1369 "%s: HVM does not support vbd %d as xen block device\n",
1370 __FUNCTION__, vdevice);
1371 return -ENODEV;
1372 }
1373 }
1374 /* do not create a PV cdrom device if we are an HVM guest */
1375 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1376 if (IS_ERR(type))
1377 return -ENODEV;
1378 if (strncmp(type, "cdrom", 5) == 0) {
1379 kfree(type);
1380 return -ENODEV;
1381 }
1382 kfree(type);
1383 }
1384 info = kzalloc(sizeof(*info), GFP_KERNEL);
1385 if (!info) {
1386 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1387 return -ENOMEM;
1388 }
1389
1390 mutex_init(&info->mutex);
1391 spin_lock_init(&info->io_lock);
1392 info->xbdev = dev;
1393 info->vdevice = vdevice;
1394 INIT_LIST_HEAD(&info->grants);
1395 INIT_LIST_HEAD(&info->indirect_pages);
1396 info->persistent_gnts_c = 0;
1397 info->connected = BLKIF_STATE_DISCONNECTED;
1398 INIT_WORK(&info->work, blkif_restart_queue);
1399
1400 for (i = 0; i < BLK_RING_SIZE; i++)
1401 info->shadow[i].req.u.rw.id = i+1;
1402 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1403
1404 /* Front end dir is a number, which is used as the id. */
1405 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1406 dev_set_drvdata(&dev->dev, info);
1407
1408 err = talk_to_blkback(dev, info);
1409 if (err) {
1410 kfree(info);
1411 dev_set_drvdata(&dev->dev, NULL);
1412 return err;
1413 }
1414
1415 return 0;
1416}
1417
1418static void split_bio_end(struct bio *bio, int error)
1419{
1420 struct split_bio *split_bio = bio->bi_private;
1421
1422 if (error)
1423 split_bio->err = error;
1424
1425 if (atomic_dec_and_test(&split_bio->pending)) {
1426 split_bio->bio->bi_phys_segments = 0;
1427 bio_endio(split_bio->bio, split_bio->err);
1428 kfree(split_bio);
1429 }
1430 bio_put(bio);
1431}
1432
1433static int blkif_recover(struct blkfront_info *info)
1434{
1435 int i;
1436 struct request *req, *n;
1437 struct blk_shadow *copy;
1438 int rc;
1439 struct bio *bio, *cloned_bio;
1440 struct bio_list bio_list, merge_bio;
1441 unsigned int segs, offset;
1442 int pending, size;
1443 struct split_bio *split_bio;
1444 struct list_head requests;
1445
1446 /* Stage 1: Make a safe copy of the shadow state. */
1447 copy = kmemdup(info->shadow, sizeof(info->shadow),
1448 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1449 if (!copy)
1450 return -ENOMEM;
1451
1452 /* Stage 2: Set up free list. */
1453 memset(&info->shadow, 0, sizeof(info->shadow));
1454 for (i = 0; i < BLK_RING_SIZE; i++)
1455 info->shadow[i].req.u.rw.id = i+1;
1456 info->shadow_free = info->ring.req_prod_pvt;
1457 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1458
1459 rc = blkfront_setup_indirect(info);
1460 if (rc) {
1461 kfree(copy);
1462 return rc;
1463 }
1464
1465 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
1466 blk_queue_max_segments(info->rq, segs);
1467 bio_list_init(&bio_list);
1468 INIT_LIST_HEAD(&requests);
1469 for (i = 0; i < BLK_RING_SIZE; i++) {
1470 /* Not in use? */
1471 if (!copy[i].request)
1472 continue;
1473
1474 /*
1475 * Get the bios in the request so we can re-queue them.
1476 */
1477 if (copy[i].request->cmd_flags &
1478 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1479 /*
1480 * Flush operations don't contain bios, so
1481 * we need to requeue the whole request
1482 */
1483 list_add(©[i].request->queuelist, &requests);
1484 continue;
1485 }
1486 merge_bio.head = copy[i].request->bio;
1487 merge_bio.tail = copy[i].request->biotail;
1488 bio_list_merge(&bio_list, &merge_bio);
1489 copy[i].request->bio = NULL;
1490 blk_put_request(copy[i].request);
1491 }
1492
1493 kfree(copy);
1494
1495 /*
1496 * Empty the queue, this is important because we might have
1497 * requests in the queue with more segments than what we
1498 * can handle now.
1499 */
1500 spin_lock_irq(&info->io_lock);
1501 while ((req = blk_fetch_request(info->rq)) != NULL) {
1502 if (req->cmd_flags &
1503 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1504 list_add(&req->queuelist, &requests);
1505 continue;
1506 }
1507 merge_bio.head = req->bio;
1508 merge_bio.tail = req->biotail;
1509 bio_list_merge(&bio_list, &merge_bio);
1510 req->bio = NULL;
1511 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA))
1512 pr_alert("diskcache flush request found!\n");
1513 __blk_put_request(info->rq, req);
1514 }
1515 spin_unlock_irq(&info->io_lock);
1516
1517 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1518
1519 spin_lock_irq(&info->io_lock);
1520
1521 /* Now safe for us to use the shared ring */
1522 info->connected = BLKIF_STATE_CONNECTED;
1523
1524 /* Kick any other new requests queued since we resumed */
1525 kick_pending_request_queues(info);
1526
1527 list_for_each_entry_safe(req, n, &requests, queuelist) {
1528 /* Requeue pending requests (flush or discard) */
1529 list_del_init(&req->queuelist);
1530 BUG_ON(req->nr_phys_segments > segs);
1531 blk_requeue_request(info->rq, req);
1532 }
1533 spin_unlock_irq(&info->io_lock);
1534
1535 while ((bio = bio_list_pop(&bio_list)) != NULL) {
1536 /* Traverse the list of pending bios and re-queue them */
1537 if (bio_segments(bio) > segs) {
1538 /*
1539 * This bio has more segments than what we can
1540 * handle, we have to split it.
1541 */
1542 pending = (bio_segments(bio) + segs - 1) / segs;
1543 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
1544 BUG_ON(split_bio == NULL);
1545 atomic_set(&split_bio->pending, pending);
1546 split_bio->bio = bio;
1547 for (i = 0; i < pending; i++) {
1548 offset = (i * segs * PAGE_SIZE) >> 9;
1549 size = min((unsigned int)(segs * PAGE_SIZE) >> 9,
1550 (unsigned int)bio_sectors(bio) - offset);
1551 cloned_bio = bio_clone(bio, GFP_NOIO);
1552 BUG_ON(cloned_bio == NULL);
1553 bio_trim(cloned_bio, offset, size);
1554 cloned_bio->bi_private = split_bio;
1555 cloned_bio->bi_end_io = split_bio_end;
1556 submit_bio(cloned_bio->bi_rw, cloned_bio);
1557 }
1558 /*
1559 * Now we have to wait for all those smaller bios to
1560 * end, so we can also end the "parent" bio.
1561 */
1562 continue;
1563 }
1564 /* We don't need to split this bio */
1565 submit_bio(bio->bi_rw, bio);
1566 }
1567
1568 return 0;
1569}
1570
1571/**
1572 * We are reconnecting to the backend, due to a suspend/resume, or a backend
1573 * driver restart. We tear down our blkif structure and recreate it, but
1574 * leave the device-layer structures intact so that this is transparent to the
1575 * rest of the kernel.
1576 */
1577static int blkfront_resume(struct xenbus_device *dev)
1578{
1579 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1580 int err;
1581
1582 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1583
1584 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1585
1586 err = talk_to_blkback(dev, info);
1587
1588 /*
1589 * We have to wait for the backend to switch to
1590 * connected state, since we want to read which
1591 * features it supports.
1592 */
1593
1594 return err;
1595}
1596
1597static void
1598blkfront_closing(struct blkfront_info *info)
1599{
1600 struct xenbus_device *xbdev = info->xbdev;
1601 struct block_device *bdev = NULL;
1602
1603 mutex_lock(&info->mutex);
1604
1605 if (xbdev->state == XenbusStateClosing) {
1606 mutex_unlock(&info->mutex);
1607 return;
1608 }
1609
1610 if (info->gd)
1611 bdev = bdget_disk(info->gd, 0);
1612
1613 mutex_unlock(&info->mutex);
1614
1615 if (!bdev) {
1616 xenbus_frontend_closed(xbdev);
1617 return;
1618 }
1619
1620 mutex_lock(&bdev->bd_mutex);
1621
1622 if (bdev->bd_openers) {
1623 xenbus_dev_error(xbdev, -EBUSY,
1624 "Device in use; refusing to close");
1625 xenbus_switch_state(xbdev, XenbusStateClosing);
1626 } else {
1627 xlvbd_release_gendisk(info);
1628 xenbus_frontend_closed(xbdev);
1629 }
1630
1631 mutex_unlock(&bdev->bd_mutex);
1632 bdput(bdev);
1633}
1634
1635static void blkfront_setup_discard(struct blkfront_info *info)
1636{
1637 int err;
1638 char *type;
1639 unsigned int discard_granularity;
1640 unsigned int discard_alignment;
1641 unsigned int discard_secure;
1642
1643 type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
1644 if (IS_ERR(type))
1645 return;
1646
1647 info->feature_secdiscard = 0;
1648 if (strncmp(type, "phy", 3) == 0) {
1649 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1650 "discard-granularity", "%u", &discard_granularity,
1651 "discard-alignment", "%u", &discard_alignment,
1652 NULL);
1653 if (!err) {
1654 info->feature_discard = 1;
1655 info->discard_granularity = discard_granularity;
1656 info->discard_alignment = discard_alignment;
1657 }
1658 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1659 "discard-secure", "%d", &discard_secure,
1660 NULL);
1661 if (!err)
1662 info->feature_secdiscard = discard_secure;
1663
1664 } else if (strncmp(type, "file", 4) == 0)
1665 info->feature_discard = 1;
1666
1667 kfree(type);
1668}
1669
1670static int blkfront_setup_indirect(struct blkfront_info *info)
1671{
1672 unsigned int indirect_segments, segs;
1673 int err, i;
1674
1675 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1676 "feature-max-indirect-segments", "%u", &indirect_segments,
1677 NULL);
1678 if (err) {
1679 info->max_indirect_segments = 0;
1680 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
1681 } else {
1682 info->max_indirect_segments = min(indirect_segments,
1683 xen_blkif_max_segments);
1684 segs = info->max_indirect_segments;
1685 }
1686
1687 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE);
1688 if (err)
1689 goto out_of_memory;
1690
1691 if (!info->feature_persistent && info->max_indirect_segments) {
1692 /*
1693 * We are using indirect descriptors but not persistent
1694 * grants, we need to allocate a set of pages that can be
1695 * used for mapping indirect grefs
1696 */
1697 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE;
1698
1699 BUG_ON(!list_empty(&info->indirect_pages));
1700 for (i = 0; i < num; i++) {
1701 struct page *indirect_page = alloc_page(GFP_NOIO);
1702 if (!indirect_page)
1703 goto out_of_memory;
1704 list_add(&indirect_page->lru, &info->indirect_pages);
1705 }
1706 }
1707
1708 for (i = 0; i < BLK_RING_SIZE; i++) {
1709 info->shadow[i].grants_used = kzalloc(
1710 sizeof(info->shadow[i].grants_used[0]) * segs,
1711 GFP_NOIO);
1712 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO);
1713 if (info->max_indirect_segments)
1714 info->shadow[i].indirect_grants = kzalloc(
1715 sizeof(info->shadow[i].indirect_grants[0]) *
1716 INDIRECT_GREFS(segs),
1717 GFP_NOIO);
1718 if ((info->shadow[i].grants_used == NULL) ||
1719 (info->shadow[i].sg == NULL) ||
1720 (info->max_indirect_segments &&
1721 (info->shadow[i].indirect_grants == NULL)))
1722 goto out_of_memory;
1723 sg_init_table(info->shadow[i].sg, segs);
1724 }
1725
1726
1727 return 0;
1728
1729out_of_memory:
1730 for (i = 0; i < BLK_RING_SIZE; i++) {
1731 kfree(info->shadow[i].grants_used);
1732 info->shadow[i].grants_used = NULL;
1733 kfree(info->shadow[i].sg);
1734 info->shadow[i].sg = NULL;
1735 kfree(info->shadow[i].indirect_grants);
1736 info->shadow[i].indirect_grants = NULL;
1737 }
1738 if (!list_empty(&info->indirect_pages)) {
1739 struct page *indirect_page, *n;
1740 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
1741 list_del(&indirect_page->lru);
1742 __free_page(indirect_page);
1743 }
1744 }
1745 return -ENOMEM;
1746}
1747
1748/*
1749 * Invoked when the backend is finally 'ready' (and has told produced
1750 * the details about the physical device - #sectors, size, etc).
1751 */
1752static void blkfront_connect(struct blkfront_info *info)
1753{
1754 unsigned long long sectors;
1755 unsigned long sector_size;
1756 unsigned int physical_sector_size;
1757 unsigned int binfo;
1758 int err;
1759 int barrier, flush, discard, persistent;
1760
1761 switch (info->connected) {
1762 case BLKIF_STATE_CONNECTED:
1763 /*
1764 * Potentially, the back-end may be signalling
1765 * a capacity change; update the capacity.
1766 */
1767 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1768 "sectors", "%Lu", §ors);
1769 if (XENBUS_EXIST_ERR(err))
1770 return;
1771 printk(KERN_INFO "Setting capacity to %Lu\n",
1772 sectors);
1773 set_capacity(info->gd, sectors);
1774 revalidate_disk(info->gd);
1775
1776 return;
1777 case BLKIF_STATE_SUSPENDED:
1778 /*
1779 * If we are recovering from suspension, we need to wait
1780 * for the backend to announce it's features before
1781 * reconnecting, at least we need to know if the backend
1782 * supports indirect descriptors, and how many.
1783 */
1784 blkif_recover(info);
1785 return;
1786
1787 default:
1788 break;
1789 }
1790
1791 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1792 __func__, info->xbdev->otherend);
1793
1794 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1795 "sectors", "%llu", §ors,
1796 "info", "%u", &binfo,
1797 "sector-size", "%lu", §or_size,
1798 NULL);
1799 if (err) {
1800 xenbus_dev_fatal(info->xbdev, err,
1801 "reading backend fields at %s",
1802 info->xbdev->otherend);
1803 return;
1804 }
1805
1806 /*
1807 * physcial-sector-size is a newer field, so old backends may not
1808 * provide this. Assume physical sector size to be the same as
1809 * sector_size in that case.
1810 */
1811 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1812 "physical-sector-size", "%u", &physical_sector_size);
1813 if (err != 1)
1814 physical_sector_size = sector_size;
1815
1816 info->feature_flush = 0;
1817 info->flush_op = 0;
1818
1819 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1820 "feature-barrier", "%d", &barrier,
1821 NULL);
1822
1823 /*
1824 * If there's no "feature-barrier" defined, then it means
1825 * we're dealing with a very old backend which writes
1826 * synchronously; nothing to do.
1827 *
1828 * If there are barriers, then we use flush.
1829 */
1830 if (!err && barrier) {
1831 info->feature_flush = REQ_FLUSH | REQ_FUA;
1832 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1833 }
1834 /*
1835 * And if there is "feature-flush-cache" use that above
1836 * barriers.
1837 */
1838 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1839 "feature-flush-cache", "%d", &flush,
1840 NULL);
1841
1842 if (!err && flush) {
1843 info->feature_flush = REQ_FLUSH;
1844 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1845 }
1846
1847 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1848 "feature-discard", "%d", &discard,
1849 NULL);
1850
1851 if (!err && discard)
1852 blkfront_setup_discard(info);
1853
1854 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1855 "feature-persistent", "%u", &persistent,
1856 NULL);
1857 if (err)
1858 info->feature_persistent = 0;
1859 else
1860 info->feature_persistent = persistent;
1861
1862 err = blkfront_setup_indirect(info);
1863 if (err) {
1864 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
1865 info->xbdev->otherend);
1866 return;
1867 }
1868
1869 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
1870 physical_sector_size);
1871 if (err) {
1872 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1873 info->xbdev->otherend);
1874 return;
1875 }
1876
1877 xenbus_switch_state(info->xbdev, XenbusStateConnected);
1878
1879 /* Kick pending requests. */
1880 spin_lock_irq(&info->io_lock);
1881 info->connected = BLKIF_STATE_CONNECTED;
1882 kick_pending_request_queues(info);
1883 spin_unlock_irq(&info->io_lock);
1884
1885 add_disk(info->gd);
1886
1887 info->is_ready = 1;
1888}
1889
1890/**
1891 * Callback received when the backend's state changes.
1892 */
1893static void blkback_changed(struct xenbus_device *dev,
1894 enum xenbus_state backend_state)
1895{
1896 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1897
1898 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1899
1900 switch (backend_state) {
1901 case XenbusStateInitialising:
1902 case XenbusStateInitWait:
1903 case XenbusStateInitialised:
1904 case XenbusStateReconfiguring:
1905 case XenbusStateReconfigured:
1906 case XenbusStateUnknown:
1907 break;
1908
1909 case XenbusStateConnected:
1910 blkfront_connect(info);
1911 break;
1912
1913 case XenbusStateClosed:
1914 if (dev->state == XenbusStateClosed)
1915 break;
1916 /* Missed the backend's Closing state -- fallthrough */
1917 case XenbusStateClosing:
1918 blkfront_closing(info);
1919 break;
1920 }
1921}
1922
1923static int blkfront_remove(struct xenbus_device *xbdev)
1924{
1925 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1926 struct block_device *bdev = NULL;
1927 struct gendisk *disk;
1928
1929 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1930
1931 blkif_free(info, 0);
1932
1933 mutex_lock(&info->mutex);
1934
1935 disk = info->gd;
1936 if (disk)
1937 bdev = bdget_disk(disk, 0);
1938
1939 info->xbdev = NULL;
1940 mutex_unlock(&info->mutex);
1941
1942 if (!bdev) {
1943 kfree(info);
1944 return 0;
1945 }
1946
1947 /*
1948 * The xbdev was removed before we reached the Closed
1949 * state. See if it's safe to remove the disk. If the bdev
1950 * isn't closed yet, we let release take care of it.
1951 */
1952
1953 mutex_lock(&bdev->bd_mutex);
1954 info = disk->private_data;
1955
1956 dev_warn(disk_to_dev(disk),
1957 "%s was hot-unplugged, %d stale handles\n",
1958 xbdev->nodename, bdev->bd_openers);
1959
1960 if (info && !bdev->bd_openers) {
1961 xlvbd_release_gendisk(info);
1962 disk->private_data = NULL;
1963 kfree(info);
1964 }
1965
1966 mutex_unlock(&bdev->bd_mutex);
1967 bdput(bdev);
1968
1969 return 0;
1970}
1971
1972static int blkfront_is_ready(struct xenbus_device *dev)
1973{
1974 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1975
1976 return info->is_ready && info->xbdev;
1977}
1978
1979static int blkif_open(struct block_device *bdev, fmode_t mode)
1980{
1981 struct gendisk *disk = bdev->bd_disk;
1982 struct blkfront_info *info;
1983 int err = 0;
1984
1985 mutex_lock(&blkfront_mutex);
1986
1987 info = disk->private_data;
1988 if (!info) {
1989 /* xbdev gone */
1990 err = -ERESTARTSYS;
1991 goto out;
1992 }
1993
1994 mutex_lock(&info->mutex);
1995
1996 if (!info->gd)
1997 /* xbdev is closed */
1998 err = -ERESTARTSYS;
1999
2000 mutex_unlock(&info->mutex);
2001
2002out:
2003 mutex_unlock(&blkfront_mutex);
2004 return err;
2005}
2006
2007static void blkif_release(struct gendisk *disk, fmode_t mode)
2008{
2009 struct blkfront_info *info = disk->private_data;
2010 struct block_device *bdev;
2011 struct xenbus_device *xbdev;
2012
2013 mutex_lock(&blkfront_mutex);
2014
2015 bdev = bdget_disk(disk, 0);
2016
2017 if (!bdev) {
2018 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2019 goto out_mutex;
2020 }
2021 if (bdev->bd_openers)
2022 goto out;
2023
2024 /*
2025 * Check if we have been instructed to close. We will have
2026 * deferred this request, because the bdev was still open.
2027 */
2028
2029 mutex_lock(&info->mutex);
2030 xbdev = info->xbdev;
2031
2032 if (xbdev && xbdev->state == XenbusStateClosing) {
2033 /* pending switch to state closed */
2034 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2035 xlvbd_release_gendisk(info);
2036 xenbus_frontend_closed(info->xbdev);
2037 }
2038
2039 mutex_unlock(&info->mutex);
2040
2041 if (!xbdev) {
2042 /* sudden device removal */
2043 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2044 xlvbd_release_gendisk(info);
2045 disk->private_data = NULL;
2046 kfree(info);
2047 }
2048
2049out:
2050 bdput(bdev);
2051out_mutex:
2052 mutex_unlock(&blkfront_mutex);
2053}
2054
2055static const struct block_device_operations xlvbd_block_fops =
2056{
2057 .owner = THIS_MODULE,
2058 .open = blkif_open,
2059 .release = blkif_release,
2060 .getgeo = blkif_getgeo,
2061 .ioctl = blkif_ioctl,
2062};
2063
2064
2065static const struct xenbus_device_id blkfront_ids[] = {
2066 { "vbd" },
2067 { "" }
2068};
2069
2070static DEFINE_XENBUS_DRIVER(blkfront, ,
2071 .probe = blkfront_probe,
2072 .remove = blkfront_remove,
2073 .resume = blkfront_resume,
2074 .otherend_changed = blkback_changed,
2075 .is_ready = blkfront_is_ready,
2076);
2077
2078static int __init xlblk_init(void)
2079{
2080 int ret;
2081
2082 if (!xen_domain())
2083 return -ENODEV;
2084
2085 if (!xen_has_pv_disk_devices())
2086 return -ENODEV;
2087
2088 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2089 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2090 XENVBD_MAJOR, DEV_NAME);
2091 return -ENODEV;
2092 }
2093
2094 ret = xenbus_register_frontend(&blkfront_driver);
2095 if (ret) {
2096 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2097 return ret;
2098 }
2099
2100 return 0;
2101}
2102module_init(xlblk_init);
2103
2104
2105static void __exit xlblk_exit(void)
2106{
2107 xenbus_unregister_driver(&blkfront_driver);
2108 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2109 kfree(minors);
2110}
2111module_exit(xlblk_exit);
2112
2113MODULE_DESCRIPTION("Xen virtual block device frontend");
2114MODULE_LICENSE("GPL");
2115MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2116MODULE_ALIAS("xen:vbd");
2117MODULE_ALIAS("xenblk");