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Root/drivers/block/xen-blkfront.c

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
48	#include <xen/xen.h>
49	#include <xen/xenbus.h>
50	#include <xen/grant_table.h>
51	#include <xen/events.h>
52	#include <xen/page.h>
53	#include <xen/platform_pci.h>
54
55	#include <xen/interface/grant_table.h>
56	#include <xen/interface/io/blkif.h>
57	#include <xen/interface/io/protocols.h>
58
59	#include <asm/xen/hypervisor.h>
60
61	enum blkif_state {
62	BLKIF_STATE_DISCONNECTED,
63	BLKIF_STATE_CONNECTED,
64	BLKIF_STATE_SUSPENDED,
65	};
66
67	struct blk_shadow {
68	struct blkif_request req;
69	struct request *request;
70	unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
71	};
72
73	static DEFINE_MUTEX(blkfront_mutex);
74	static const struct block_device_operations xlvbd_block_fops;
75
76	#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
77
78	/*
79	* We have one of these per vbd, whether ide, scsi or 'other'. They
80	* hang in private_data off the gendisk structure. We may end up
81	* putting all kinds of interesting stuff here :-)
82	*/
83	struct blkfront_info
84	{
85	spinlock_t io_lock;
86	struct mutex mutex;
87	struct xenbus_device *xbdev;
88	struct gendisk *gd;
89	int vdevice;
90	blkif_vdev_t handle;
91	enum blkif_state connected;
92	int ring_ref;
93	struct blkif_front_ring ring;
94	struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
95	unsigned int evtchn, irq;
96	struct request_queue *rq;
97	struct work_struct work;
98	struct gnttab_free_callback callback;
99	struct blk_shadow shadow[BLK_RING_SIZE];
100	unsigned long shadow_free;
101	unsigned int feature_flush;
102	unsigned int flush_op;
103	unsigned int feature_discard:1;
104	unsigned int feature_secdiscard:1;
105	unsigned int discard_granularity;
106	unsigned int discard_alignment;
107	int is_ready;
108	};
109
110	static unsigned int nr_minors;
111	static unsigned long *minors;
112	static DEFINE_SPINLOCK(minor_lock);
113
114	#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
115	(BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
116	#define GRANT_INVALID_REF 0
117
118	#define PARTS_PER_DISK 16
119	#define PARTS_PER_EXT_DISK 256
120
121	#define BLKIF_MAJOR(dev) ((dev)>>8)
122	#define BLKIF_MINOR(dev) ((dev) & 0xff)
123
124	#define EXT_SHIFT 28
125	#define EXTENDED (1<<EXT_SHIFT)
126	#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
127	#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
128	#define EMULATED_HD_DISK_MINOR_OFFSET (0)
129	#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
130	#define EMULATED_SD_DISK_MINOR_OFFSET (0)
131	#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
132
133	#define DEV_NAME "xvd" /* name in /dev */
134
135	static int get_id_from_freelist(struct blkfront_info *info)
136	{
137	unsigned long free = info->shadow_free;
138	BUG_ON(free >= BLK_RING_SIZE);
139	info->shadow_free = info->shadow[free].req.u.rw.id;
140	info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
141	return free;
142	}
143
144	static int add_id_to_freelist(struct blkfront_info *info,
145	unsigned long id)
146	{
147	if (info->shadow[id].req.u.rw.id != id)
148	return -EINVAL;
149	if (info->shadow[id].request == NULL)
150	return -EINVAL;
151	info->shadow[id].req.u.rw.id = info->shadow_free;
152	info->shadow[id].request = NULL;
153	info->shadow_free = id;
154	return 0;
155	}
156
157	static const char *op_name(int op)
158	{
159	static const char *const names[] = {
160	[BLKIF_OP_READ] = "read",
161	[BLKIF_OP_WRITE] = "write",
162	[BLKIF_OP_WRITE_BARRIER] = "barrier",
163	[BLKIF_OP_FLUSH_DISKCACHE] = "flush",
164	[BLKIF_OP_DISCARD] = "discard" };
165
166	if (op < 0 \|\| op >= ARRAY_SIZE(names))
167	return "unknown";
168
169	if (!names[op])
170	return "reserved";
171
172	return names[op];
173	}
174	static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
175	{
176	unsigned int end = minor + nr;
177	int rc;
178
179	if (end > nr_minors) {
180	unsigned long bitmap, old;
181
182	bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
183	GFP_KERNEL);
184	if (bitmap == NULL)
185	return -ENOMEM;
186
187	spin_lock(&minor_lock);
188	if (end > nr_minors) {
189	old = minors;
190	memcpy(bitmap, minors,
191	BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
192	minors = bitmap;
193	nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
194	} else
195	old = bitmap;
196	spin_unlock(&minor_lock);
197	kfree(old);
198	}
199
200	spin_lock(&minor_lock);
201	if (find_next_bit(minors, end, minor) >= end) {
202	bitmap_set(minors, minor, nr);
203	rc = 0;
204	} else
205	rc = -EBUSY;
206	spin_unlock(&minor_lock);
207
208	return rc;
209	}
210
211	static void xlbd_release_minors(unsigned int minor, unsigned int nr)
212	{
213	unsigned int end = minor + nr;
214
215	BUG_ON(end > nr_minors);
216	spin_lock(&minor_lock);
217	bitmap_clear(minors, minor, nr);
218	spin_unlock(&minor_lock);
219	}
220
221	static void blkif_restart_queue_callback(void *arg)
222	{
223	struct blkfront_info info = (struct blkfront_info )arg;
224	schedule_work(&info->work);
225	}
226
227	static int blkif_getgeo(struct block_device bd, struct hd_geometry hg)
228	{
229	/* We don't have real geometry info, but let's at least return
230	values consistent with the size of the device */
231	sector_t nsect = get_capacity(bd->bd_disk);
232	sector_t cylinders = nsect;
233
234	hg->heads = 0xff;
235	hg->sectors = 0x3f;
236	sector_div(cylinders, hg->heads * hg->sectors);
237	hg->cylinders = cylinders;
238	if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
239	hg->cylinders = 0xffff;
240	return 0;
241	}
242
243	static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
244	unsigned command, unsigned long argument)
245	{
246	struct blkfront_info *info = bdev->bd_disk->private_data;
247	int i;
248
249	dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
250	command, (long)argument);
251
252	switch (command) {
253	case CDROMMULTISESSION:
254	dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
255	for (i = 0; i < sizeof(struct cdrom_multisession); i++)
256	if (put_user(0, (char __user *)(argument + i)))
257	return -EFAULT;
258	return 0;
259
260	case CDROM_GET_CAPABILITY: {
261	struct gendisk *gd = info->gd;
262	if (gd->flags & GENHD_FL_CD)
263	return 0;
264	return -EINVAL;
265	}
266
267	default:
268	/*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
269	command);*/
270	return -EINVAL; /* same return as native Linux */
271	}
272
273	return 0;
274	}
275
276	/*
277	* Generate a Xen blkfront IO request from a blk layer request. Reads
278	* and writes are handled as expected.
279	*
280	* @req: a request struct
281	*/
282	static int blkif_queue_request(struct request *req)
283	{
284	struct blkfront_info *info = req->rq_disk->private_data;
285	unsigned long buffer_mfn;
286	struct blkif_request *ring_req;
287	unsigned long id;
288	unsigned int fsect, lsect;
289	int i, ref;
290	grant_ref_t gref_head;
291	struct scatterlist *sg;
292
293	if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
294	return 1;
295
296	if (gnttab_alloc_grant_references(
297	BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
298	gnttab_request_free_callback(
299	&info->callback,
300	blkif_restart_queue_callback,
301	info,
302	BLKIF_MAX_SEGMENTS_PER_REQUEST);
303	return 1;
304	}
305
306	/* Fill out a communications ring structure. */
307	ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
308	id = get_id_from_freelist(info);
309	info->shadow[id].request = req;
310
311	ring_req->u.rw.id = id;
312	ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
313	ring_req->u.rw.handle = info->handle;
314
315	ring_req->operation = rq_data_dir(req) ?
316	BLKIF_OP_WRITE : BLKIF_OP_READ;
317
318	if (req->cmd_flags & (REQ_FLUSH \| REQ_FUA)) {
319	/*
320	* Ideally we can do an unordered flush-to-disk. In case the
321	* backend onlysupports barriers, use that. A barrier request
322	* a superset of FUA, so we can implement it the same
323	* way. (It's also a FLUSH+FUA, since it is
324	* guaranteed ordered WRT previous writes.)
325	*/
326	ring_req->operation = info->flush_op;
327	}
328
329	if (unlikely(req->cmd_flags & (REQ_DISCARD \| REQ_SECURE))) {
330	/* id, sector_number and handle are set above. */
331	ring_req->operation = BLKIF_OP_DISCARD;
332	ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
333	if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
334	ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
335	else
336	ring_req->u.discard.flag = 0;
337	} else {
338	ring_req->u.rw.nr_segments = blk_rq_map_sg(req->q, req,
339	info->sg);
340	BUG_ON(ring_req->u.rw.nr_segments >
341	BLKIF_MAX_SEGMENTS_PER_REQUEST);
342
343	for_each_sg(info->sg, sg, ring_req->u.rw.nr_segments, i) {
344	buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
345	fsect = sg->offset >> 9;
346	lsect = fsect + (sg->length >> 9) - 1;
347	/* install a grant reference. */
348	ref = gnttab_claim_grant_reference(&gref_head);
349	BUG_ON(ref == -ENOSPC);
350
351	gnttab_grant_foreign_access_ref(
352	ref,
353	info->xbdev->otherend_id,
354	buffer_mfn,
355	rq_data_dir(req));
356
357	info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
358	ring_req->u.rw.seg[i] =
359	(struct blkif_request_segment) {
360	.gref = ref,
361	.first_sect = fsect,
362	.last_sect = lsect };
363	}
364	}
365
366	info->ring.req_prod_pvt++;
367
368	/* Keep a private copy so we can reissue requests when recovering. */
369	info->shadow[id].req = *ring_req;
370
371	gnttab_free_grant_references(gref_head);
372
373	return 0;
374	}
375
376
377	static inline void flush_requests(struct blkfront_info *info)
378	{
379	int notify;
380
381	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
382
383	if (notify)
384	notify_remote_via_irq(info->irq);
385	}
386
387	/*
388	* do_blkif_request
389	* read a block; request is in a request queue
390	*/
391	static void do_blkif_request(struct request_queue *rq)
392	{
393	struct blkfront_info *info = NULL;
394	struct request *req;
395	int queued;
396
397	pr_debug("Entered do_blkif_request\n");
398
399	queued = 0;
400
401	while ((req = blk_peek_request(rq)) != NULL) {
402	info = req->rq_disk->private_data;
403
404	if (RING_FULL(&info->ring))
405	goto wait;
406
407	blk_start_request(req);
408
409	if ((req->cmd_type != REQ_TYPE_FS) \|\|
410	((req->cmd_flags & (REQ_FLUSH \| REQ_FUA)) &&
411	!info->flush_op)) {
412	__blk_end_request_all(req, -EIO);
413	continue;
414	}
415
416	pr_debug("do_blk_req %p: cmd %p, sec %lx, "
417	"(%u/%u) buffer:%p [%s]\n",
418	req, req->cmd, (unsigned long)blk_rq_pos(req),
419	blk_rq_cur_sectors(req), blk_rq_sectors(req),
420	req->buffer, rq_data_dir(req) ? "write" : "read");
421
422	if (blkif_queue_request(req)) {
423	blk_requeue_request(rq, req);
424	wait:
425	/* Avoid pointless unplugs. */
426	blk_stop_queue(rq);
427	break;
428	}
429
430	queued++;
431	}
432
433	if (queued != 0)
434	flush_requests(info);
435	}
436
437	static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
438	{
439	struct request_queue *rq;
440	struct blkfront_info *info = gd->private_data;
441
442	rq = blk_init_queue(do_blkif_request, &info->io_lock);
443	if (rq == NULL)
444	return -1;
445
446	queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
447
448	if (info->feature_discard) {
449	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
450	blk_queue_max_discard_sectors(rq, get_capacity(gd));
451	rq->limits.discard_granularity = info->discard_granularity;
452	rq->limits.discard_alignment = info->discard_alignment;
453	if (info->feature_secdiscard)
454	queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
455	}
456
457	/* Hard sector size and max sectors impersonate the equiv. hardware. */
458	blk_queue_logical_block_size(rq, sector_size);
459	blk_queue_max_hw_sectors(rq, 512);
460
461	/* Each segment in a request is up to an aligned page in size. */
462	blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
463	blk_queue_max_segment_size(rq, PAGE_SIZE);
464
465	/* Ensure a merged request will fit in a single I/O ring slot. */
466	blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
467
468	/* Make sure buffer addresses are sector-aligned. */
469	blk_queue_dma_alignment(rq, 511);
470
471	/* Make sure we don't use bounce buffers. */
472	blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
473
474	gd->queue = rq;
475
476	return 0;
477	}
478
479
480	static void xlvbd_flush(struct blkfront_info *info)
481	{
482	blk_queue_flush(info->rq, info->feature_flush);
483	printk(KERN_INFO "blkfront: %s: %s: %s\n",
484	info->gd->disk_name,
485	info->flush_op == BLKIF_OP_WRITE_BARRIER ?
486	"barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
487	"flush diskcache" : "barrier or flush"),
488	info->feature_flush ? "enabled" : "disabled");
489	}
490
491	static int xen_translate_vdev(int vdevice, int minor, unsigned int offset)
492	{
493	int major;
494	major = BLKIF_MAJOR(vdevice);
495	*minor = BLKIF_MINOR(vdevice);
496	switch (major) {
497	case XEN_IDE0_MAJOR:
498	offset = (minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
499	minor = ((minor / 64) * PARTS_PER_DISK) +
500	EMULATED_HD_DISK_MINOR_OFFSET;
501	break;
502	case XEN_IDE1_MAJOR:
503	offset = (minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
504	minor = (((minor / 64) + 2) * PARTS_PER_DISK) +
505	EMULATED_HD_DISK_MINOR_OFFSET;
506	break;
507	case XEN_SCSI_DISK0_MAJOR:
508	offset = (minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
509	minor = minor + EMULATED_SD_DISK_MINOR_OFFSET;
510	break;
511	case XEN_SCSI_DISK1_MAJOR:
512	case XEN_SCSI_DISK2_MAJOR:
513	case XEN_SCSI_DISK3_MAJOR:
514	case XEN_SCSI_DISK4_MAJOR:
515	case XEN_SCSI_DISK5_MAJOR:
516	case XEN_SCSI_DISK6_MAJOR:
517	case XEN_SCSI_DISK7_MAJOR:
518	offset = (minor / PARTS_PER_DISK) +
519	((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
520	EMULATED_SD_DISK_NAME_OFFSET;
521	minor = minor +
522	((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
523	EMULATED_SD_DISK_MINOR_OFFSET;
524	break;
525	case XEN_SCSI_DISK8_MAJOR:
526	case XEN_SCSI_DISK9_MAJOR:
527	case XEN_SCSI_DISK10_MAJOR:
528	case XEN_SCSI_DISK11_MAJOR:
529	case XEN_SCSI_DISK12_MAJOR:
530	case XEN_SCSI_DISK13_MAJOR:
531	case XEN_SCSI_DISK14_MAJOR:
532	case XEN_SCSI_DISK15_MAJOR:
533	offset = (minor / PARTS_PER_DISK) +
534	((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
535	EMULATED_SD_DISK_NAME_OFFSET;
536	minor = minor +
537	((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
538	EMULATED_SD_DISK_MINOR_OFFSET;
539	break;
540	case XENVBD_MAJOR:
541	offset = minor / PARTS_PER_DISK;
542	break;
543	default:
544	printk(KERN_WARNING "blkfront: your disk configuration is "
545	"incorrect, please use an xvd device instead\n");
546	return -ENODEV;
547	}
548	return 0;
549	}
550
551	static char encode_disk_name(char ptr, unsigned int n)
552	{
553	if (n >= 26)
554	ptr = encode_disk_name(ptr, n / 26 - 1);
555	*ptr = 'a' + n % 26;
556	return ptr + 1;
557	}
558
559	static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
560	struct blkfront_info *info,
561	u16 vdisk_info, u16 sector_size)
562	{
563	struct gendisk *gd;
564	int nr_minors = 1;
565	int err;
566	unsigned int offset;
567	int minor;
568	int nr_parts;
569	char *ptr;
570
571	BUG_ON(info->gd != NULL);
572	BUG_ON(info->rq != NULL);
573
574	if ((info->vdevice>>EXT_SHIFT) > 1) {
575	/* this is above the extended range; something is wrong */
576	printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
577	return -ENODEV;
578	}
579
580	if (!VDEV_IS_EXTENDED(info->vdevice)) {
581	err = xen_translate_vdev(info->vdevice, &minor, &offset);
582	if (err)
583	return err;
584	nr_parts = PARTS_PER_DISK;
585	} else {
586	minor = BLKIF_MINOR_EXT(info->vdevice);
587	nr_parts = PARTS_PER_EXT_DISK;
588	offset = minor / nr_parts;
589	if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
590	printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
591	"emulated IDE disks,\n\t choose an xvd device name"
592	"from xvde on\n", info->vdevice);
593	}
594	if (minor >> MINORBITS) {
595	pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
596	info->vdevice, minor);
597	return -ENODEV;
598	}
599
600	if ((minor % nr_parts) == 0)
601	nr_minors = nr_parts;
602
603	err = xlbd_reserve_minors(minor, nr_minors);
604	if (err)
605	goto out;
606	err = -ENODEV;
607
608	gd = alloc_disk(nr_minors);
609	if (gd == NULL)
610	goto release;
611
612	strcpy(gd->disk_name, DEV_NAME);
613	ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
614	BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
615	if (nr_minors > 1)
616	*ptr = 0;
617	else
618	snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
619	"%d", minor & (nr_parts - 1));
620
621	gd->major = XENVBD_MAJOR;
622	gd->first_minor = minor;
623	gd->fops = &xlvbd_block_fops;
624	gd->private_data = info;
625	gd->driverfs_dev = &(info->xbdev->dev);
626	set_capacity(gd, capacity);
627
628	if (xlvbd_init_blk_queue(gd, sector_size)) {
629	del_gendisk(gd);
630	goto release;
631	}
632
633	info->rq = gd->queue;
634	info->gd = gd;
635
636	xlvbd_flush(info);
637
638	if (vdisk_info & VDISK_READONLY)
639	set_disk_ro(gd, 1);
640
641	if (vdisk_info & VDISK_REMOVABLE)
642	gd->flags \|= GENHD_FL_REMOVABLE;
643
644	if (vdisk_info & VDISK_CDROM)
645	gd->flags \|= GENHD_FL_CD;
646
647	return 0;
648
649	release:
650	xlbd_release_minors(minor, nr_minors);
651	out:
652	return err;
653	}
654
655	static void xlvbd_release_gendisk(struct blkfront_info *info)
656	{
657	unsigned int minor, nr_minors;
658	unsigned long flags;
659
660	if (info->rq == NULL)
661	return;
662
663	spin_lock_irqsave(&info->io_lock, flags);
664
665	/* No more blkif_request(). */
666	blk_stop_queue(info->rq);
667
668	/* No more gnttab callback work. */
669	gnttab_cancel_free_callback(&info->callback);
670	spin_unlock_irqrestore(&info->io_lock, flags);
671
672	/* Flush gnttab callback work. Must be done with no locks held. */
673	flush_work_sync(&info->work);
674
675	del_gendisk(info->gd);
676
677	minor = info->gd->first_minor;
678	nr_minors = info->gd->minors;
679	xlbd_release_minors(minor, nr_minors);
680
681	blk_cleanup_queue(info->rq);
682	info->rq = NULL;
683
684	put_disk(info->gd);
685	info->gd = NULL;
686	}
687
688	static void kick_pending_request_queues(struct blkfront_info *info)
689	{
690	if (!RING_FULL(&info->ring)) {
691	/* Re-enable calldowns. */
692	blk_start_queue(info->rq);
693	/* Kick things off immediately. */
694	do_blkif_request(info->rq);
695	}
696	}
697
698	static void blkif_restart_queue(struct work_struct *work)
699	{
700	struct blkfront_info *info = container_of(work, struct blkfront_info, work);
701
702	spin_lock_irq(&info->io_lock);
703	if (info->connected == BLKIF_STATE_CONNECTED)
704	kick_pending_request_queues(info);
705	spin_unlock_irq(&info->io_lock);
706	}
707
708	static void blkif_free(struct blkfront_info *info, int suspend)
709	{
710	/* Prevent new requests being issued until we fix things up. */
711	spin_lock_irq(&info->io_lock);
712	info->connected = suspend ?
713	BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
714	/* No more blkif_request(). */
715	if (info->rq)
716	blk_stop_queue(info->rq);
717	/* No more gnttab callback work. */
718	gnttab_cancel_free_callback(&info->callback);
719	spin_unlock_irq(&info->io_lock);
720
721	/* Flush gnttab callback work. Must be done with no locks held. */
722	flush_work_sync(&info->work);
723
724	/* Free resources associated with old device channel. */
725	if (info->ring_ref != GRANT_INVALID_REF) {
726	gnttab_end_foreign_access(info->ring_ref, 0,
727	(unsigned long)info->ring.sring);
728	info->ring_ref = GRANT_INVALID_REF;
729	info->ring.sring = NULL;
730	}
731	if (info->irq)
732	unbind_from_irqhandler(info->irq, info);
733	info->evtchn = info->irq = 0;
734
735	}
736
737	static void blkif_completion(struct blk_shadow *s)
738	{
739	int i;
740	/* Do not let BLKIF_OP_DISCARD as nr_segment is in the same place
741	* flag. */
742	for (i = 0; i < s->req.u.rw.nr_segments; i++)
743	gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
744	}
745
746	static irqreturn_t blkif_interrupt(int irq, void *dev_id)
747	{
748	struct request *req;
749	struct blkif_response *bret;
750	RING_IDX i, rp;
751	unsigned long flags;
752	struct blkfront_info info = (struct blkfront_info )dev_id;
753	int error;
754
755	spin_lock_irqsave(&info->io_lock, flags);
756
757	if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
758	spin_unlock_irqrestore(&info->io_lock, flags);
759	return IRQ_HANDLED;
760	}
761
762	again:
763	rp = info->ring.sring->rsp_prod;
764	rmb(); /* Ensure we see queued responses up to 'rp'. */
765
766	for (i = info->ring.rsp_cons; i != rp; i++) {
767	unsigned long id;
768
769	bret = RING_GET_RESPONSE(&info->ring, i);
770	id = bret->id;
771	/*
772	* The backend has messed up and given us an id that we would
773	* never have given to it (we stamp it up to BLK_RING_SIZE -
774	* look in get_id_from_freelist.
775	*/
776	if (id >= BLK_RING_SIZE) {
777	WARN(1, "%s: response to %s has incorrect id (%ld)\n",
778	info->gd->disk_name, op_name(bret->operation), id);
779	/* We can't safely get the 'struct request' as
780	* the id is busted. */
781	continue;
782	}
783	req = info->shadow[id].request;
784
785	if (bret->operation != BLKIF_OP_DISCARD)
786	blkif_completion(&info->shadow[id]);
787
788	if (add_id_to_freelist(info, id)) {
789	WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
790	info->gd->disk_name, op_name(bret->operation), id);
791	continue;
792	}
793
794	error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
795	switch (bret->operation) {
796	case BLKIF_OP_DISCARD:
797	if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
798	struct request_queue *rq = info->rq;
799	printk(KERN_WARNING "blkfront: %s: %s op failed\n",
800	info->gd->disk_name, op_name(bret->operation));
801	error = -EOPNOTSUPP;
802	info->feature_discard = 0;
803	info->feature_secdiscard = 0;
804	queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
805	queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
806	}
807	__blk_end_request_all(req, error);
808	break;
809	case BLKIF_OP_FLUSH_DISKCACHE:
810	case BLKIF_OP_WRITE_BARRIER:
811	if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
812	printk(KERN_WARNING "blkfront: %s: %s op failed\n",
813	info->gd->disk_name, op_name(bret->operation));
814	error = -EOPNOTSUPP;
815	}
816	if (unlikely(bret->status == BLKIF_RSP_ERROR &&
817	info->shadow[id].req.u.rw.nr_segments == 0)) {
818	printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
819	info->gd->disk_name, op_name(bret->operation));
820	error = -EOPNOTSUPP;
821	}
822	if (unlikely(error)) {
823	if (error == -EOPNOTSUPP)
824	error = 0;
825	info->feature_flush = 0;
826	info->flush_op = 0;
827	xlvbd_flush(info);
828	}
829	/* fall through */
830	case BLKIF_OP_READ:
831	case BLKIF_OP_WRITE:
832	if (unlikely(bret->status != BLKIF_RSP_OKAY))
833	dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
834	"request: %x\n", bret->status);
835
836	__blk_end_request_all(req, error);
837	break;
838	default:
839	BUG();
840	}
841	}
842
843	info->ring.rsp_cons = i;
844
845	if (i != info->ring.req_prod_pvt) {
846	int more_to_do;
847	RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
848	if (more_to_do)
849	goto again;
850	} else
851	info->ring.sring->rsp_event = i + 1;
852
853	kick_pending_request_queues(info);
854
855	spin_unlock_irqrestore(&info->io_lock, flags);
856
857	return IRQ_HANDLED;
858	}
859
860
861	static int setup_blkring(struct xenbus_device *dev,
862	struct blkfront_info *info)
863	{
864	struct blkif_sring *sring;
865	int err;
866
867	info->ring_ref = GRANT_INVALID_REF;
868
869	sring = (struct blkif_sring *)__get_free_page(GFP_NOIO \| __GFP_HIGH);
870	if (!sring) {
871	xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
872	return -ENOMEM;
873	}
874	SHARED_RING_INIT(sring);
875	FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
876
877	sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
878
879	err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
880	if (err < 0) {
881	free_page((unsigned long)sring);
882	info->ring.sring = NULL;
883	goto fail;
884	}
885	info->ring_ref = err;
886
887	err = xenbus_alloc_evtchn(dev, &info->evtchn);
888	if (err)
889	goto fail;
890
891	err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
892	"blkif", info);
893	if (err <= 0) {
894	xenbus_dev_fatal(dev, err,
895	"bind_evtchn_to_irqhandler failed");
896	goto fail;
897	}
898	info->irq = err;
899
900	return 0;
901	fail:
902	blkif_free(info, 0);
903	return err;
904	}
905
906
907	/* Common code used when first setting up, and when resuming. */
908	static int talk_to_blkback(struct xenbus_device *dev,
909	struct blkfront_info *info)
910	{
911	const char *message = NULL;
912	struct xenbus_transaction xbt;
913	int err;
914
915	/* Create shared ring, alloc event channel. */
916	err = setup_blkring(dev, info);
917	if (err)
918	goto out;
919
920	again:
921	err = xenbus_transaction_start(&xbt);
922	if (err) {
923	xenbus_dev_fatal(dev, err, "starting transaction");
924	goto destroy_blkring;
925	}
926
927	err = xenbus_printf(xbt, dev->nodename,
928	"ring-ref", "%u", info->ring_ref);
929	if (err) {
930	message = "writing ring-ref";
931	goto abort_transaction;
932	}
933	err = xenbus_printf(xbt, dev->nodename,
934	"event-channel", "%u", info->evtchn);
935	if (err) {
936	message = "writing event-channel";
937	goto abort_transaction;
938	}
939	err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
940	XEN_IO_PROTO_ABI_NATIVE);
941	if (err) {
942	message = "writing protocol";
943	goto abort_transaction;
944	}
945
946	err = xenbus_transaction_end(xbt, 0);
947	if (err) {
948	if (err == -EAGAIN)
949	goto again;
950	xenbus_dev_fatal(dev, err, "completing transaction");
951	goto destroy_blkring;
952	}
953
954	xenbus_switch_state(dev, XenbusStateInitialised);
955
956	return 0;
957
958	abort_transaction:
959	xenbus_transaction_end(xbt, 1);
960	if (message)
961	xenbus_dev_fatal(dev, err, "%s", message);
962	destroy_blkring:
963	blkif_free(info, 0);
964	out:
965	return err;
966	}
967
968	/**
969	* Entry point to this code when a new device is created. Allocate the basic
970	* structures and the ring buffer for communication with the backend, and
971	* inform the backend of the appropriate details for those. Switch to
972	* Initialised state.
973	*/
974	static int blkfront_probe(struct xenbus_device *dev,
975	const struct xenbus_device_id *id)
976	{
977	int err, vdevice, i;
978	struct blkfront_info *info;
979
980	/* FIXME: Use dynamic device id if this is not set. */
981	err = xenbus_scanf(XBT_NIL, dev->nodename,
982	"virtual-device", "%i", &vdevice);
983	if (err != 1) {
984	/* go looking in the extended area instead */
985	err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
986	"%i", &vdevice);
987	if (err != 1) {
988	xenbus_dev_fatal(dev, err, "reading virtual-device");
989	return err;
990	}
991	}
992
993	if (xen_hvm_domain()) {
994	char *type;
995	int len;
996	/* no unplug has been done: do not hook devices != xen vbds */
997	if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
998	int major;
999
1000	if (!VDEV_IS_EXTENDED(vdevice))
1001	major = BLKIF_MAJOR(vdevice);
1002	else
1003	major = XENVBD_MAJOR;
1004
1005	if (major != XENVBD_MAJOR) {
1006	printk(KERN_INFO
1007	"%s: HVM does not support vbd %d as xen block device\n",
1008	__FUNCTION__, vdevice);
1009	return -ENODEV;
1010	}
1011	}
1012	/* do not create a PV cdrom device if we are an HVM guest */
1013	type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1014	if (IS_ERR(type))
1015	return -ENODEV;
1016	if (strncmp(type, "cdrom", 5) == 0) {
1017	kfree(type);
1018	return -ENODEV;
1019	}
1020	kfree(type);
1021	}
1022	info = kzalloc(sizeof(*info), GFP_KERNEL);
1023	if (!info) {
1024	xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1025	return -ENOMEM;
1026	}
1027
1028	mutex_init(&info->mutex);
1029	spin_lock_init(&info->io_lock);
1030	info->xbdev = dev;
1031	info->vdevice = vdevice;
1032	info->connected = BLKIF_STATE_DISCONNECTED;
1033	INIT_WORK(&info->work, blkif_restart_queue);
1034
1035	for (i = 0; i < BLK_RING_SIZE; i++)
1036	info->shadow[i].req.u.rw.id = i+1;
1037	info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1038
1039	/* Front end dir is a number, which is used as the id. */
1040	info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1041	dev_set_drvdata(&dev->dev, info);
1042
1043	err = talk_to_blkback(dev, info);
1044	if (err) {
1045	kfree(info);
1046	dev_set_drvdata(&dev->dev, NULL);
1047	return err;
1048	}
1049
1050	return 0;
1051	}
1052
1053
1054	static int blkif_recover(struct blkfront_info *info)
1055	{
1056	int i;
1057	struct blkif_request *req;
1058	struct blk_shadow *copy;
1059	int j;
1060
1061	/* Stage 1: Make a safe copy of the shadow state. */
1062	copy = kmalloc(sizeof(info->shadow),
1063	GFP_NOIO \| __GFP_REPEAT \| __GFP_HIGH);
1064	if (!copy)
1065	return -ENOMEM;
1066	memcpy(copy, info->shadow, sizeof(info->shadow));
1067
1068	/* Stage 2: Set up free list. */
1069	memset(&info->shadow, 0, sizeof(info->shadow));
1070	for (i = 0; i < BLK_RING_SIZE; i++)
1071	info->shadow[i].req.u.rw.id = i+1;
1072	info->shadow_free = info->ring.req_prod_pvt;
1073	info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1074
1075	/* Stage 3: Find pending requests and requeue them. */
1076	for (i = 0; i < BLK_RING_SIZE; i++) {
1077	/* Not in use? */
1078	if (!copy[i].request)
1079	continue;
1080
1081	/* Grab a request slot and copy shadow state into it. */
1082	req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
1083	*req = copy[i].req;
1084
1085	/* We get a new request id, and must reset the shadow state. */
1086	req->u.rw.id = get_id_from_freelist(info);
1087	memcpy(&info->shadow[req->u.rw.id], &copy[i], sizeof(copy[i]));
1088
1089	if (req->operation != BLKIF_OP_DISCARD) {
1090	/* Rewrite any grant references invalidated by susp/resume. */
1091	for (j = 0; j < req->u.rw.nr_segments; j++)
1092	gnttab_grant_foreign_access_ref(
1093	req->u.rw.seg[j].gref,
1094	info->xbdev->otherend_id,
1095	pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]),
1096	rq_data_dir(info->shadow[req->u.rw.id].request));
1097	}
1098	info->shadow[req->u.rw.id].req = *req;
1099
1100	info->ring.req_prod_pvt++;
1101	}
1102
1103	kfree(copy);
1104
1105	xenbus_switch_state(info->xbdev, XenbusStateConnected);
1106
1107	spin_lock_irq(&info->io_lock);
1108
1109	/* Now safe for us to use the shared ring */
1110	info->connected = BLKIF_STATE_CONNECTED;
1111
1112	/* Send off requeued requests */
1113	flush_requests(info);
1114
1115	/* Kick any other new requests queued since we resumed */
1116	kick_pending_request_queues(info);
1117
1118	spin_unlock_irq(&info->io_lock);
1119
1120	return 0;
1121	}
1122
1123	/**
1124	* We are reconnecting to the backend, due to a suspend/resume, or a backend
1125	* driver restart. We tear down our blkif structure and recreate it, but
1126	* leave the device-layer structures intact so that this is transparent to the
1127	* rest of the kernel.
1128	*/
1129	static int blkfront_resume(struct xenbus_device *dev)
1130	{
1131	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1132	int err;
1133
1134	dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1135
1136	blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1137
1138	err = talk_to_blkback(dev, info);
1139	if (info->connected == BLKIF_STATE_SUSPENDED && !err)
1140	err = blkif_recover(info);
1141
1142	return err;
1143	}
1144
1145	static void
1146	blkfront_closing(struct blkfront_info *info)
1147	{
1148	struct xenbus_device *xbdev = info->xbdev;
1149	struct block_device *bdev = NULL;
1150
1151	mutex_lock(&info->mutex);
1152
1153	if (xbdev->state == XenbusStateClosing) {
1154	mutex_unlock(&info->mutex);
1155	return;
1156	}
1157
1158	if (info->gd)
1159	bdev = bdget_disk(info->gd, 0);
1160
1161	mutex_unlock(&info->mutex);
1162
1163	if (!bdev) {
1164	xenbus_frontend_closed(xbdev);
1165	return;
1166	}
1167
1168	mutex_lock(&bdev->bd_mutex);
1169
1170	if (bdev->bd_openers) {
1171	xenbus_dev_error(xbdev, -EBUSY,
1172	"Device in use; refusing to close");
1173	xenbus_switch_state(xbdev, XenbusStateClosing);
1174	} else {
1175	xlvbd_release_gendisk(info);
1176	xenbus_frontend_closed(xbdev);
1177	}
1178
1179	mutex_unlock(&bdev->bd_mutex);
1180	bdput(bdev);
1181	}
1182
1183	static void blkfront_setup_discard(struct blkfront_info *info)
1184	{
1185	int err;
1186	char *type;
1187	unsigned int discard_granularity;
1188	unsigned int discard_alignment;
1189	unsigned int discard_secure;
1190
1191	type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
1192	if (IS_ERR(type))
1193	return;
1194
1195	info->feature_secdiscard = 0;
1196	if (strncmp(type, "phy", 3) == 0) {
1197	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1198	"discard-granularity", "%u", &discard_granularity,
1199	"discard-alignment", "%u", &discard_alignment,
1200	NULL);
1201	if (!err) {
1202	info->feature_discard = 1;
1203	info->discard_granularity = discard_granularity;
1204	info->discard_alignment = discard_alignment;
1205	}
1206	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1207	"discard-secure", "%d", &discard_secure,
1208	NULL);
1209	if (!err)
1210	info->feature_secdiscard = discard_secure;
1211
1212	} else if (strncmp(type, "file", 4) == 0)
1213	info->feature_discard = 1;
1214
1215	kfree(type);
1216	}
1217
1218	/*
1219	* Invoked when the backend is finally 'ready' (and has told produced
1220	* the details about the physical device - #sectors, size, etc).
1221	*/
1222	static void blkfront_connect(struct blkfront_info *info)
1223	{
1224	unsigned long long sectors;
1225	unsigned long sector_size;
1226	unsigned int binfo;
1227	int err;
1228	int barrier, flush, discard;
1229
1230	switch (info->connected) {
1231	case BLKIF_STATE_CONNECTED:
1232	/*
1233	* Potentially, the back-end may be signalling
1234	* a capacity change; update the capacity.
1235	*/
1236	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1237	"sectors", "%Lu", &sectors);
1238	if (XENBUS_EXIST_ERR(err))
1239	return;
1240	printk(KERN_INFO "Setting capacity to %Lu\n",
1241	sectors);
1242	set_capacity(info->gd, sectors);
1243	revalidate_disk(info->gd);
1244
1245	/* fall through */
1246	case BLKIF_STATE_SUSPENDED:
1247	return;
1248
1249	default:
1250	break;
1251	}
1252
1253	dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1254	__func__, info->xbdev->otherend);
1255
1256	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1257	"sectors", "%llu", &sectors,
1258	"info", "%u", &binfo,
1259	"sector-size", "%lu", &sector_size,
1260	NULL);
1261	if (err) {
1262	xenbus_dev_fatal(info->xbdev, err,
1263	"reading backend fields at %s",
1264	info->xbdev->otherend);
1265	return;
1266	}
1267
1268	info->feature_flush = 0;
1269	info->flush_op = 0;
1270
1271	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1272	"feature-barrier", "%d", &barrier,
1273	NULL);
1274
1275	/*
1276	* If there's no "feature-barrier" defined, then it means
1277	* we're dealing with a very old backend which writes
1278	* synchronously; nothing to do.
1279	*
1280	* If there are barriers, then we use flush.
1281	*/
1282	if (!err && barrier) {
1283	info->feature_flush = REQ_FLUSH \| REQ_FUA;
1284	info->flush_op = BLKIF_OP_WRITE_BARRIER;
1285	}
1286	/*
1287	* And if there is "feature-flush-cache" use that above
1288	* barriers.
1289	*/
1290	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1291	"feature-flush-cache", "%d", &flush,
1292	NULL);
1293
1294	if (!err && flush) {
1295	info->feature_flush = REQ_FLUSH;
1296	info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1297	}
1298
1299	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1300	"feature-discard", "%d", &discard,
1301	NULL);
1302
1303	if (!err && discard)
1304	blkfront_setup_discard(info);
1305
1306	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1307	if (err) {
1308	xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1309	info->xbdev->otherend);
1310	return;
1311	}
1312
1313	xenbus_switch_state(info->xbdev, XenbusStateConnected);
1314
1315	/* Kick pending requests. */
1316	spin_lock_irq(&info->io_lock);
1317	info->connected = BLKIF_STATE_CONNECTED;
1318	kick_pending_request_queues(info);
1319	spin_unlock_irq(&info->io_lock);
1320
1321	add_disk(info->gd);
1322
1323	info->is_ready = 1;
1324	}
1325
1326	/**
1327	* Callback received when the backend's state changes.
1328	*/
1329	static void blkback_changed(struct xenbus_device *dev,
1330	enum xenbus_state backend_state)
1331	{
1332	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1333
1334	dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1335
1336	switch (backend_state) {
1337	case XenbusStateInitialising:
1338	case XenbusStateInitWait:
1339	case XenbusStateInitialised:
1340	case XenbusStateReconfiguring:
1341	case XenbusStateReconfigured:
1342	case XenbusStateUnknown:
1343	case XenbusStateClosed:
1344	break;
1345
1346	case XenbusStateConnected:
1347	blkfront_connect(info);
1348	break;
1349
1350	case XenbusStateClosing:
1351	blkfront_closing(info);
1352	break;
1353	}
1354	}
1355
1356	static int blkfront_remove(struct xenbus_device *xbdev)
1357	{
1358	struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1359	struct block_device *bdev = NULL;
1360	struct gendisk *disk;
1361
1362	dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1363
1364	blkif_free(info, 0);
1365
1366	mutex_lock(&info->mutex);
1367
1368	disk = info->gd;
1369	if (disk)
1370	bdev = bdget_disk(disk, 0);
1371
1372	info->xbdev = NULL;
1373	mutex_unlock(&info->mutex);
1374
1375	if (!bdev) {
1376	kfree(info);
1377	return 0;
1378	}
1379
1380	/*
1381	* The xbdev was removed before we reached the Closed
1382	* state. See if it's safe to remove the disk. If the bdev
1383	* isn't closed yet, we let release take care of it.
1384	*/
1385
1386	mutex_lock(&bdev->bd_mutex);
1387	info = disk->private_data;
1388
1389	dev_warn(disk_to_dev(disk),
1390	"%s was hot-unplugged, %d stale handles\n",
1391	xbdev->nodename, bdev->bd_openers);
1392
1393	if (info && !bdev->bd_openers) {
1394	xlvbd_release_gendisk(info);
1395	disk->private_data = NULL;
1396	kfree(info);
1397	}
1398
1399	mutex_unlock(&bdev->bd_mutex);
1400	bdput(bdev);
1401
1402	return 0;
1403	}
1404
1405	static int blkfront_is_ready(struct xenbus_device *dev)
1406	{
1407	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1408
1409	return info->is_ready && info->xbdev;
1410	}
1411
1412	static int blkif_open(struct block_device *bdev, fmode_t mode)
1413	{
1414	struct gendisk *disk = bdev->bd_disk;
1415	struct blkfront_info *info;
1416	int err = 0;
1417
1418	mutex_lock(&blkfront_mutex);
1419
1420	info = disk->private_data;
1421	if (!info) {
1422	/* xbdev gone */
1423	err = -ERESTARTSYS;
1424	goto out;
1425	}
1426
1427	mutex_lock(&info->mutex);
1428
1429	if (!info->gd)
1430	/* xbdev is closed */
1431	err = -ERESTARTSYS;
1432
1433	mutex_unlock(&info->mutex);
1434
1435	out:
1436	mutex_unlock(&blkfront_mutex);
1437	return err;
1438	}
1439
1440	static int blkif_release(struct gendisk *disk, fmode_t mode)
1441	{
1442	struct blkfront_info *info = disk->private_data;
1443	struct block_device *bdev;
1444	struct xenbus_device *xbdev;
1445
1446	mutex_lock(&blkfront_mutex);
1447
1448	bdev = bdget_disk(disk, 0);
1449
1450	if (bdev->bd_openers)
1451	goto out;
1452
1453	/*
1454	* Check if we have been instructed to close. We will have
1455	* deferred this request, because the bdev was still open.
1456	*/
1457
1458	mutex_lock(&info->mutex);
1459	xbdev = info->xbdev;
1460
1461	if (xbdev && xbdev->state == XenbusStateClosing) {
1462	/* pending switch to state closed */
1463	dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1464	xlvbd_release_gendisk(info);
1465	xenbus_frontend_closed(info->xbdev);
1466	}
1467
1468	mutex_unlock(&info->mutex);
1469
1470	if (!xbdev) {
1471	/* sudden device removal */
1472	dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1473	xlvbd_release_gendisk(info);
1474	disk->private_data = NULL;
1475	kfree(info);
1476	}
1477
1478	out:
1479	bdput(bdev);
1480	mutex_unlock(&blkfront_mutex);
1481	return 0;
1482	}
1483
1484	static const struct block_device_operations xlvbd_block_fops =
1485	{
1486	.owner = THIS_MODULE,
1487	.open = blkif_open,
1488	.release = blkif_release,
1489	.getgeo = blkif_getgeo,
1490	.ioctl = blkif_ioctl,
1491	};
1492
1493
1494	static const struct xenbus_device_id blkfront_ids[] = {
1495	{ "vbd" },
1496	{ "" }
1497	};
1498
1499	static DEFINE_XENBUS_DRIVER(blkfront, ,
1500	.probe = blkfront_probe,
1501	.remove = blkfront_remove,
1502	.resume = blkfront_resume,
1503	.otherend_changed = blkback_changed,
1504	.is_ready = blkfront_is_ready,
1505	);
1506
1507	static int __init xlblk_init(void)
1508	{
1509	int ret;
1510
1511	if (!xen_domain())
1512	return -ENODEV;
1513
1514	if (xen_hvm_domain() && !xen_platform_pci_unplug)
1515	return -ENODEV;
1516
1517	if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1518	printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1519	XENVBD_MAJOR, DEV_NAME);
1520	return -ENODEV;
1521	}
1522
1523	ret = xenbus_register_frontend(&blkfront_driver);
1524	if (ret) {
1525	unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
1526	return ret;
1527	}
1528
1529	return 0;
1530	}
1531	module_init(xlblk_init);
1532
1533
1534	static void __exit xlblk_exit(void)
1535	{
1536	xenbus_unregister_driver(&blkfront_driver);
1537	unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
1538	kfree(minors);
1539	}
1540	module_exit(xlblk_exit);
1541
1542	MODULE_DESCRIPTION("Xen virtual block device frontend");
1543	MODULE_LICENSE("GPL");
1544	MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1545	MODULE_ALIAS("xen:vbd");
1546	MODULE_ALIAS("xenblk");
1547

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