1	/*
2	* blkfront.c
3	*
4	* XenLinux virtual block device driver.
5	*
6	* Copyright (c) 2003-2004, Keir Fraser & Steve Hand
7	* Modifications by Mark A. Williamson are (c) Intel Research Cambridge
8	* Copyright (c) 2004, Christian Limpach
9	* Copyright (c) 2004, Andrew Warfield
10	* Copyright (c) 2005, Christopher Clark
11	* Copyright (c) 2005, XenSource Ltd
12	*
13	* This program is free software; you can redistribute it and/or
14	* modify it under the terms of the GNU General Public License version 2
15	* as published by the Free Software Foundation; or, when distributed
16	* separately from the Linux kernel or incorporated into other
17	* software packages, subject to the following license:
18	*
19	* Permission is hereby granted, free of charge, to any person obtaining a copy
20	* of this source file (the "Software"), to deal in the Software without
21	* restriction, including without limitation the rights to use, copy, modify,
22	* merge, publish, distribute, sublicense, and/or sell copies of the Software,
23	* and to permit persons to whom the Software is furnished to do so, subject to
24	* the following conditions:
25	*
26	* The above copyright notice and this permission notice shall be included in
27	* all copies or substantial portions of the Software.
28	*
29	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
30	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
31	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
32	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
33	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
34	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
35	* IN THE SOFTWARE.
36	*/
37
38	#include <linux/interrupt.h>
39	#include <linux/blkdev.h>
40	#include <linux/blk-mq.h>
41	#include <linux/hdreg.h>
42	#include <linux/cdrom.h>
43	#include <linux/module.h>
44	#include <linux/slab.h>
45	#include <linux/major.h>
46	#include <linux/mutex.h>
47	#include <linux/scatterlist.h>
48	#include <linux/bitmap.h>
49	#include <linux/list.h>
50	#include <linux/workqueue.h>
51	#include <linux/sched/mm.h>
52
53	#include <xen/xen.h>
54	#include <xen/xenbus.h>
55	#include <xen/grant_table.h>
56	#include <xen/events.h>
57	#include <xen/page.h>
58	#include <xen/platform_pci.h>
59
60	#include <xen/interface/grant_table.h>
61	#include <xen/interface/io/blkif.h>
62	#include <xen/interface/io/protocols.h>
63
64	#include <asm/xen/hypervisor.h>
65
66	/*
67	* The minimal size of segment supported by the block framework is PAGE_SIZE.
68	* When Linux is using a different page size than Xen, it may not be possible
69	* to put all the data in a single segment.
70	* This can happen when the backend doesn't support indirect descriptor and
71	* therefore the maximum amount of data that a request can carry is
72	* BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
73	*
74	* Note that we only support one extra request. So the Linux page size
75	* should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
76	* 88KB.
77	*/
78	#define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
79
80	enum blkif_state {
81	BLKIF_STATE_DISCONNECTED,
82	BLKIF_STATE_CONNECTED,
83	BLKIF_STATE_SUSPENDED,
84	BLKIF_STATE_ERROR,
85	};
86
87	struct grant {
88	grant_ref_t gref;
89	struct page *page;
90	struct list_head node;
91	};
92
93	enum blk_req_status {
94	REQ_PROCESSING,
95	REQ_WAITING,
96	REQ_DONE,
97	REQ_ERROR,
98	REQ_EOPNOTSUPP,
99	};
100
101	struct blk_shadow {
102	struct blkif_request req;
103	struct request *request;
104	struct grant **grants_used;
105	struct grant **indirect_grants;
106	struct scatterlist *sg;
107	unsigned int num_sg;
108	enum blk_req_status status;
109
110	#define NO_ASSOCIATED_ID ~0UL
111	/*
112	* Id of the sibling if we ever need 2 requests when handling a
113	* block I/O request
114	*/
115	unsigned long associated_id;
116	};
117
118	struct blkif_req {
119	blk_status_t error;
120	};
121
122	static inline struct blkif_req *blkif_req(struct request *rq)
123	{
124	return blk_mq_rq_to_pdu(rq);
125	}
126
127	static DEFINE_MUTEX(blkfront_mutex);
128	static const struct block_device_operations xlvbd_block_fops;
129	static struct delayed_work blkfront_work;
130	static LIST_HEAD(info_list);
131
132	/*
133	* Maximum number of segments in indirect requests, the actual value used by
134	* the frontend driver is the minimum of this value and the value provided
135	* by the backend driver.
136	*/
137
138	static unsigned int xen_blkif_max_segments = 32;
139	module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
140	MODULE_PARM_DESC(max_indirect_segments,
141	"Maximum amount of segments in indirect requests (default is 32)");
142
143	static unsigned int xen_blkif_max_queues = 4;
144	module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
145	MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
146
147	/*
148	* Maximum order of pages to be used for the shared ring between front and
149	* backend, 4KB page granularity is used.
150	*/
151	static unsigned int xen_blkif_max_ring_order;
152	module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
153	MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
154
155	static bool __read_mostly xen_blkif_trusted = true;
156	module_param_named(trusted, xen_blkif_trusted, bool, 0644);
157	MODULE_PARM_DESC(trusted, "Is the backend trusted");
158
159	#define BLK_RING_SIZE(info) \
160	__CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
161
162	/*
163	* ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
164	* characters are enough. Define to 20 to keep consistent with backend.
165	*/
166	#define RINGREF_NAME_LEN (20)
167	/*
168	* queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
169	*/
170	#define QUEUE_NAME_LEN (17)
171
172	/*
173	* Per-ring info.
174	* Every blkfront device can associate with one or more blkfront_ring_info,
175	* depending on how many hardware queues/rings to be used.
176	*/
177	struct blkfront_ring_info {
178	/* Lock to protect data in every ring buffer. */
179	spinlock_t ring_lock;
180	struct blkif_front_ring ring;
181	unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
182	unsigned int evtchn, irq;
183	struct work_struct work;
184	struct gnttab_free_callback callback;
185	struct list_head indirect_pages;
186	struct list_head grants;
187	unsigned int persistent_gnts_c;
188	unsigned long shadow_free;
189	struct blkfront_info *dev_info;
190	struct blk_shadow shadow[];
191	};
192
193	/*
194	* We have one of these per vbd, whether ide, scsi or 'other'. They
195	* hang in private_data off the gendisk structure. We may end up
196	* putting all kinds of interesting stuff here :-)
197	*/
198	struct blkfront_info
199	{
200	struct mutex mutex;
201	struct xenbus_device *xbdev;
202	struct gendisk *gd;
203	u16 sector_size;
204	unsigned int physical_sector_size;
205	unsigned long vdisk_info;
206	int vdevice;
207	blkif_vdev_t handle;
208	enum blkif_state connected;
209	/* Number of pages per ring buffer. */
210	unsigned int nr_ring_pages;
211	struct request_queue *rq;
212	unsigned int feature_flush:1;
213	unsigned int feature_fua:1;
214	unsigned int feature_discard:1;
215	unsigned int feature_secdiscard:1;
216	/* Connect-time cached feature_persistent parameter */
217	unsigned int feature_persistent_parm:1;
218	/* Persistent grants feature negotiation result */
219	unsigned int feature_persistent:1;
220	unsigned int bounce:1;
221	unsigned int discard_granularity;
222	unsigned int discard_alignment;
223	/* Number of 4KB segments handled */
224	unsigned int max_indirect_segments;
225	int is_ready;
226	struct blk_mq_tag_set tag_set;
227	struct blkfront_ring_info *rinfo;
228	unsigned int nr_rings;
229	unsigned int rinfo_size;
230	/* Save uncomplete reqs and bios for migration. */
231	struct list_head requests;
232	struct bio_list bio_list;
233	struct list_head info_list;
234	};
235
236	static unsigned int nr_minors;
237	static unsigned long *minors;
238	static DEFINE_SPINLOCK(minor_lock);
239
240	#define PARTS_PER_DISK 16
241	#define PARTS_PER_EXT_DISK 256
242
243	#define BLKIF_MAJOR(dev) ((dev)>>8)
244	#define BLKIF_MINOR(dev) ((dev) & 0xff)
245
246	#define EXT_SHIFT 28
247	#define EXTENDED (1<<EXT_SHIFT)
248	#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
249	#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
250	#define EMULATED_HD_DISK_MINOR_OFFSET (0)
251	#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
252	#define EMULATED_SD_DISK_MINOR_OFFSET (0)
253	#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
254
255	#define DEV_NAME "xvd" /* name in /dev */
256
257	/*
258	* Grants are always the same size as a Xen page (i.e 4KB).
259	* A physical segment is always the same size as a Linux page.
260	* Number of grants per physical segment
261	*/
262	#define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
263
264	#define GRANTS_PER_INDIRECT_FRAME \
265	(XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
266
267	#define INDIRECT_GREFS(_grants) \
268	DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
269
270	static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
271	static void blkfront_gather_backend_features(struct blkfront_info *info);
272	static int negotiate_mq(struct blkfront_info *info);
273
274	#define for_each_rinfo(info, ptr, idx) \
275	for ((ptr) = (info)->rinfo, (idx) = 0; \
276	(idx) < (info)->nr_rings; \
277	(idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size)
278
279	static inline struct blkfront_ring_info *
280	get_rinfo(const struct blkfront_info *info, unsigned int i)
281	{
282	BUG_ON(i >= info->nr_rings);
283	return (void *)info->rinfo + i * info->rinfo_size;
284	}
285
286	static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
287	{
288	unsigned long free = rinfo->shadow_free;
289
290	BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
291	rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
292	rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
293	return free;
294	}
295
296	static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
297	unsigned long id)
298	{
299	if (rinfo->shadow[id].req.u.rw.id != id)
300	return -EINVAL;
301	if (rinfo->shadow[id].request == NULL)
302	return -EINVAL;
303	rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
304	rinfo->shadow[id].request = NULL;
305	rinfo->shadow_free = id;
306	return 0;
307	}
308
309	static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
310	{
311	struct blkfront_info *info = rinfo->dev_info;
312	struct page *granted_page;
313	struct grant *gnt_list_entry, *n;
314	int i = 0;
315
316	while (i < num) {
317	gnt_list_entry = kzalloc(size: sizeof(struct grant), GFP_NOIO);
318	if (!gnt_list_entry)
319	goto out_of_memory;
320
321	if (info->bounce) {
322	granted_page = alloc_page(GFP_NOIO | __GFP_ZERO);
323	if (!granted_page) {
324	kfree(objp: gnt_list_entry);
325	goto out_of_memory;
326	}
327	gnt_list_entry->page = granted_page;
328	}
329
330	gnt_list_entry->gref = INVALID_GRANT_REF;
331	list_add(new: &gnt_list_entry->node, head: &rinfo->grants);
332	i++;
333	}
334
335	return 0;
336
337	out_of_memory:
338	list_for_each_entry_safe(gnt_list_entry, n,
339	&rinfo->grants, node) {
340	list_del(entry: &gnt_list_entry->node);
341	if (info->bounce)
342	__free_page(gnt_list_entry->page);
343	kfree(objp: gnt_list_entry);
344	i--;
345	}
346	BUG_ON(i != 0);
347	return -ENOMEM;
348	}
349
350	static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
351	{
352	struct grant *gnt_list_entry;
353
354	BUG_ON(list_empty(&rinfo->grants));
355	gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
356	node);
357	list_del(entry: &gnt_list_entry->node);
358
359	if (gnt_list_entry->gref != INVALID_GRANT_REF)
360	rinfo->persistent_gnts_c--;
361
362	return gnt_list_entry;
363	}
364
365	static inline void grant_foreign_access(const struct grant *gnt_list_entry,
366	const struct blkfront_info *info)
367	{
368	gnttab_page_grant_foreign_access_ref_one(ref: gnt_list_entry->gref,
369	domid: info->xbdev->otherend_id,
370	page: gnt_list_entry->page,
371	readonly: 0);
372	}
373
374	static struct grant *get_grant(grant_ref_t *gref_head,
375	unsigned long gfn,
376	struct blkfront_ring_info *rinfo)
377	{
378	struct grant *gnt_list_entry = get_free_grant(rinfo);
379	struct blkfront_info *info = rinfo->dev_info;
380
381	if (gnt_list_entry->gref != INVALID_GRANT_REF)
382	return gnt_list_entry;
383
384	/* Assign a gref to this page */
385	gnt_list_entry->gref = gnttab_claim_grant_reference(pprivate_head: gref_head);
386	BUG_ON(gnt_list_entry->gref == -ENOSPC);
387	if (info->bounce)
388	grant_foreign_access(gnt_list_entry, info);
389	else {
390	/* Grant access to the GFN passed by the caller */
391	gnttab_grant_foreign_access_ref(ref: gnt_list_entry->gref,
392	domid: info->xbdev->otherend_id,
393	frame: gfn, readonly: 0);
394	}
395
396	return gnt_list_entry;
397	}
398
399	static struct grant *get_indirect_grant(grant_ref_t *gref_head,
400	struct blkfront_ring_info *rinfo)
401	{
402	struct grant *gnt_list_entry = get_free_grant(rinfo);
403	struct blkfront_info *info = rinfo->dev_info;
404
405	if (gnt_list_entry->gref != INVALID_GRANT_REF)
406	return gnt_list_entry;
407
408	/* Assign a gref to this page */
409	gnt_list_entry->gref = gnttab_claim_grant_reference(pprivate_head: gref_head);
410	BUG_ON(gnt_list_entry->gref == -ENOSPC);
411	if (!info->bounce) {
412	struct page *indirect_page;
413
414	/* Fetch a pre-allocated page to use for indirect grefs */
415	BUG_ON(list_empty(&rinfo->indirect_pages));
416	indirect_page = list_first_entry(&rinfo->indirect_pages,
417	struct page, lru);
418	list_del(entry: &indirect_page->lru);
419	gnt_list_entry->page = indirect_page;
420	}
421	grant_foreign_access(gnt_list_entry, info);
422
423	return gnt_list_entry;
424	}
425
426	static const char *op_name(int op)
427	{
428	static const char *const names[] = {
429	[BLKIF_OP_READ] = "read",
430	[BLKIF_OP_WRITE] = "write",
431	[BLKIF_OP_WRITE_BARRIER] = "barrier",
432	[BLKIF_OP_FLUSH_DISKCACHE] = "flush",
433	[BLKIF_OP_DISCARD] = "discard" };
434
435	if (op < 0 || op >= ARRAY_SIZE(names))
436	return "unknown";
437
438	if (!names[op])
439	return "reserved";
440
441	return names[op];
442	}
443	static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
444	{
445	unsigned int end = minor + nr;
446	int rc;
447
448	if (end > nr_minors) {
449	unsigned long *bitmap, *old;
450
451	bitmap = kcalloc(BITS_TO_LONGS(end), size: sizeof(*bitmap),
452	GFP_KERNEL);
453	if (bitmap == NULL)
454	return -ENOMEM;
455
456	spin_lock(lock: &minor_lock);
457	if (end > nr_minors) {
458	old = minors;
459	memcpy(bitmap, minors,
460	BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
461	minors = bitmap;
462	nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
463	} else
464	old = bitmap;
465	spin_unlock(lock: &minor_lock);
466	kfree(objp: old);
467	}
468
469	spin_lock(lock: &minor_lock);
470	if (find_next_bit(addr: minors, size: end, offset: minor) >= end) {
471	bitmap_set(map: minors, start: minor, nbits: nr);
472	rc = 0;
473	} else
474	rc = -EBUSY;
475	spin_unlock(lock: &minor_lock);
476
477	return rc;
478	}
479
480	static void xlbd_release_minors(unsigned int minor, unsigned int nr)
481	{
482	unsigned int end = minor + nr;
483
484	BUG_ON(end > nr_minors);
485	spin_lock(lock: &minor_lock);
486	bitmap_clear(map: minors, start: minor, nbits: nr);
487	spin_unlock(lock: &minor_lock);
488	}
489
490	static void blkif_restart_queue_callback(void *arg)
491	{
492	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
493	schedule_work(work: &rinfo->work);
494	}
495
496	static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
497	{
498	/* We don't have real geometry info, but let's at least return
499	values consistent with the size of the device */
500	sector_t nsect = get_capacity(disk: bd->bd_disk);
501	sector_t cylinders = nsect;
502
503	hg->heads = 0xff;
504	hg->sectors = 0x3f;
505	sector_div(cylinders, hg->heads * hg->sectors);
506	hg->cylinders = cylinders;
507	if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
508	hg->cylinders = 0xffff;
509	return 0;
510	}
511
512	static int blkif_ioctl(struct block_device *bdev, blk_mode_t mode,
513	unsigned command, unsigned long argument)
514	{
515	struct blkfront_info *info = bdev->bd_disk->private_data;
516	int i;
517
518	switch (command) {
519	case CDROMMULTISESSION:
520	for (i = 0; i < sizeof(struct cdrom_multisession); i++)
521	if (put_user(0, (char __user *)(argument + i)))
522	return -EFAULT;
523	return 0;
524	case CDROM_GET_CAPABILITY:
525	if (!(info->vdisk_info & VDISK_CDROM))
526	return -EINVAL;
527	return 0;
528	default:
529	return -EINVAL;
530	}
531	}
532
533	static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
534	struct request *req,
535	struct blkif_request **ring_req)
536	{
537	unsigned long id;
538
539	*ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
540	rinfo->ring.req_prod_pvt++;
541
542	id = get_id_from_freelist(rinfo);
543	rinfo->shadow[id].request = req;
544	rinfo->shadow[id].status = REQ_PROCESSING;
545	rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
546
547	rinfo->shadow[id].req.u.rw.id = id;
548
549	return id;
550	}
551
552	static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
553	{
554	struct blkfront_info *info = rinfo->dev_info;
555	struct blkif_request *ring_req, *final_ring_req;
556	unsigned long id;
557
558	/* Fill out a communications ring structure. */
559	id = blkif_ring_get_request(rinfo, req, ring_req: &final_ring_req);
560	ring_req = &rinfo->shadow[id].req;
561
562	ring_req->operation = BLKIF_OP_DISCARD;
563	ring_req->u.discard.nr_sectors = blk_rq_sectors(rq: req);
564	ring_req->u.discard.id = id;
565	ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(rq: req);
566	if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
567	ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
568	else
569	ring_req->u.discard.flag = 0;
570
571	/* Copy the request to the ring page. */
572	*final_ring_req = *ring_req;
573	rinfo->shadow[id].status = REQ_WAITING;
574
575	return 0;
576	}
577
578	struct setup_rw_req {
579	unsigned int grant_idx;
580	struct blkif_request_segment *segments;
581	struct blkfront_ring_info *rinfo;
582	struct blkif_request *ring_req;
583	grant_ref_t gref_head;
584	unsigned int id;
585	/* Only used when persistent grant is used and it's a write request */
586	bool need_copy;
587	unsigned int bvec_off;
588	char *bvec_data;
589
590	bool require_extra_req;
591	struct blkif_request *extra_ring_req;
592	};
593
594	static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
595	unsigned int len, void *data)
596	{
597	struct setup_rw_req *setup = data;
598	int n, ref;
599	struct grant *gnt_list_entry;
600	unsigned int fsect, lsect;
601	/* Convenient aliases */
602	unsigned int grant_idx = setup->grant_idx;
603	struct blkif_request *ring_req = setup->ring_req;
604	struct blkfront_ring_info *rinfo = setup->rinfo;
605	/*
606	* We always use the shadow of the first request to store the list
607	* of grant associated to the block I/O request. This made the
608	* completion more easy to handle even if the block I/O request is
609	* split.
610	*/
611	struct blk_shadow *shadow = &rinfo->shadow[setup->id];
612
613	if (unlikely(setup->require_extra_req &&
614	grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
615	/*
616	* We are using the second request, setup grant_idx
617	* to be the index of the segment array.
618	*/
619	grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
620	ring_req = setup->extra_ring_req;
621	}
622
623	if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
624	(grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
625	if (setup->segments)
626	kunmap_atomic(setup->segments);
627
628	n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
629	gnt_list_entry = get_indirect_grant(gref_head: &setup->gref_head, rinfo);
630	shadow->indirect_grants[n] = gnt_list_entry;
631	setup->segments = kmap_atomic(page: gnt_list_entry->page);
632	ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
633	}
634
635	gnt_list_entry = get_grant(gref_head: &setup->gref_head, gfn, rinfo);
636	ref = gnt_list_entry->gref;
637	/*
638	* All the grants are stored in the shadow of the first
639	* request. Therefore we have to use the global index.
640	*/
641	shadow->grants_used[setup->grant_idx] = gnt_list_entry;
642
643	if (setup->need_copy) {
644	void *shared_data;
645
646	shared_data = kmap_atomic(page: gnt_list_entry->page);
647	/*
648	* this does not wipe data stored outside the
649	* range sg->offset..sg->offset+sg->length.
650	* Therefore, blkback *could* see data from
651	* previous requests. This is OK as long as
652	* persistent grants are shared with just one
653	* domain. It may need refactoring if this
654	* changes
655	*/
656	memcpy(shared_data + offset,
657	setup->bvec_data + setup->bvec_off,
658	len);
659
660	kunmap_atomic(shared_data);
661	setup->bvec_off += len;
662	}
663
664	fsect = offset >> 9;
665	lsect = fsect + (len >> 9) - 1;
666	if (ring_req->operation != BLKIF_OP_INDIRECT) {
667	ring_req->u.rw.seg[grant_idx] =
668	(struct blkif_request_segment) {
669	.gref = ref,
670	.first_sect = fsect,
671	.last_sect = lsect };
672	} else {
673	setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
674	(struct blkif_request_segment) {
675	.gref = ref,
676	.first_sect = fsect,
677	.last_sect = lsect };
678	}
679
680	(setup->grant_idx)++;
681	}
682
683	static void blkif_setup_extra_req(struct blkif_request *first,
684	struct blkif_request *second)
685	{
686	uint16_t nr_segments = first->u.rw.nr_segments;
687
688	/*
689	* The second request is only present when the first request uses
690	* all its segments. It's always the continuity of the first one.
691	*/
692	first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
693
694	second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
695	second->u.rw.sector_number = first->u.rw.sector_number +
696	(BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
697
698	second->u.rw.handle = first->u.rw.handle;
699	second->operation = first->operation;
700	}
701
702	static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
703	{
704	struct blkfront_info *info = rinfo->dev_info;
705	struct blkif_request *ring_req, *extra_ring_req = NULL;
706	struct blkif_request *final_ring_req, *final_extra_ring_req = NULL;
707	unsigned long id, extra_id = NO_ASSOCIATED_ID;
708	bool require_extra_req = false;
709	int i;
710	struct setup_rw_req setup = {
711	.grant_idx = 0,
712	.segments = NULL,
713	.rinfo = rinfo,
714	.need_copy = rq_data_dir(req) && info->bounce,
715	};
716
717	/*
718	* Used to store if we are able to queue the request by just using
719	* existing persistent grants, or if we have to get new grants,
720	* as there are not sufficiently many free.
721	*/
722	bool new_persistent_gnts = false;
723	struct scatterlist *sg;
724	int num_sg, max_grefs, num_grant;
725
726	max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
727	if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
728	/*
729	* If we are using indirect segments we need to account
730	* for the indirect grefs used in the request.
731	*/
732	max_grefs += INDIRECT_GREFS(max_grefs);
733
734	/* Check if we have enough persistent grants to allocate a requests */
735	if (rinfo->persistent_gnts_c < max_grefs) {
736	new_persistent_gnts = true;
737
738	if (gnttab_alloc_grant_references(
739	count: max_grefs - rinfo->persistent_gnts_c,
740	pprivate_head: &setup.gref_head) < 0) {
741	gnttab_request_free_callback(
742	callback: &rinfo->callback,
743	fn: blkif_restart_queue_callback,
744	arg: rinfo,
745	count: max_grefs - rinfo->persistent_gnts_c);
746	return 1;
747	}
748	}
749
750	/* Fill out a communications ring structure. */
751	id = blkif_ring_get_request(rinfo, req, ring_req: &final_ring_req);
752	ring_req = &rinfo->shadow[id].req;
753
754	num_sg = blk_rq_map_sg(q: req->q, rq: req, sglist: rinfo->shadow[id].sg);
755	num_grant = 0;
756	/* Calculate the number of grant used */
757	for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
758	num_grant += gnttab_count_grant(start: sg->offset, len: sg->length);
759
760	require_extra_req = info->max_indirect_segments == 0 &&
761	num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
762	BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
763
764	rinfo->shadow[id].num_sg = num_sg;
765	if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
766	likely(!require_extra_req)) {
767	/*
768	* The indirect operation can only be a BLKIF_OP_READ or
769	* BLKIF_OP_WRITE
770	*/
771	BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
772	ring_req->operation = BLKIF_OP_INDIRECT;
773	ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
774	BLKIF_OP_WRITE : BLKIF_OP_READ;
775	ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(rq: req);
776	ring_req->u.indirect.handle = info->handle;
777	ring_req->u.indirect.nr_segments = num_grant;
778	} else {
779	ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(rq: req);
780	ring_req->u.rw.handle = info->handle;
781	ring_req->operation = rq_data_dir(req) ?
782	BLKIF_OP_WRITE : BLKIF_OP_READ;
783	if (req_op(req) == REQ_OP_FLUSH ||
784	(req_op(req) == REQ_OP_WRITE && (req->cmd_flags & REQ_FUA))) {
785	/*
786	* Ideally we can do an unordered flush-to-disk.
787	* In case the backend onlysupports barriers, use that.
788	* A barrier request a superset of FUA, so we can
789	* implement it the same way. (It's also a FLUSH+FUA,
790	* since it is guaranteed ordered WRT previous writes.)
791	*/
792	if (info->feature_flush && info->feature_fua)
793	ring_req->operation =
794	BLKIF_OP_WRITE_BARRIER;
795	else if (info->feature_flush)
796	ring_req->operation =
797	BLKIF_OP_FLUSH_DISKCACHE;
798	else
799	ring_req->operation = 0;
800	}
801	ring_req->u.rw.nr_segments = num_grant;
802	if (unlikely(require_extra_req)) {
803	extra_id = blkif_ring_get_request(rinfo, req,
804	ring_req: &final_extra_ring_req);
805	extra_ring_req = &rinfo->shadow[extra_id].req;
806
807	/*
808	* Only the first request contains the scatter-gather
809	* list.
810	*/
811	rinfo->shadow[extra_id].num_sg = 0;
812
813	blkif_setup_extra_req(first: ring_req, second: extra_ring_req);
814
815	/* Link the 2 requests together */
816	rinfo->shadow[extra_id].associated_id = id;
817	rinfo->shadow[id].associated_id = extra_id;
818	}
819	}
820
821	setup.ring_req = ring_req;
822	setup.id = id;
823
824	setup.require_extra_req = require_extra_req;
825	if (unlikely(require_extra_req))
826	setup.extra_ring_req = extra_ring_req;
827
828	for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
829	BUG_ON(sg->offset + sg->length > PAGE_SIZE);
830
831	if (setup.need_copy) {
832	setup.bvec_off = sg->offset;
833	setup.bvec_data = kmap_atomic(page: sg_page(sg));
834	}
835
836	gnttab_foreach_grant_in_range(page: sg_page(sg),
837	offset: sg->offset,
838	len: sg->length,
839	fn: blkif_setup_rw_req_grant,
840	data: &setup);
841
842	if (setup.need_copy)
843	kunmap_atomic(setup.bvec_data);
844	}
845	if (setup.segments)
846	kunmap_atomic(setup.segments);
847
848	/* Copy request(s) to the ring page. */
849	*final_ring_req = *ring_req;
850	rinfo->shadow[id].status = REQ_WAITING;
851	if (unlikely(require_extra_req)) {
852	*final_extra_ring_req = *extra_ring_req;
853	rinfo->shadow[extra_id].status = REQ_WAITING;
854	}
855
856	if (new_persistent_gnts)
857	gnttab_free_grant_references(head: setup.gref_head);
858
859	return 0;
860	}
861
862	/*
863	* Generate a Xen blkfront IO request from a blk layer request. Reads
864	* and writes are handled as expected.
865	*
866	* @req: a request struct
867	*/
868	static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
869	{
870	if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
871	return 1;
872
873	if (unlikely(req_op(req) == REQ_OP_DISCARD ||
874	req_op(req) == REQ_OP_SECURE_ERASE))
875	return blkif_queue_discard_req(req, rinfo);
876	else
877	return blkif_queue_rw_req(req, rinfo);
878	}
879
880	static inline void flush_requests(struct blkfront_ring_info *rinfo)
881	{
882	int notify;
883
884	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
885
886	if (notify)
887	notify_remote_via_irq(irq: rinfo->irq);
888	}
889
890	static inline bool blkif_request_flush_invalid(struct request *req,
891	struct blkfront_info *info)
892	{
893	return (blk_rq_is_passthrough(rq: req) ||
894	((req_op(req) == REQ_OP_FLUSH) &&
895	!info->feature_flush) ||
896	((req->cmd_flags & REQ_FUA) &&
897	!info->feature_fua));
898	}
899
900	static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
901	const struct blk_mq_queue_data *qd)
902	{
903	unsigned long flags;
904	int qid = hctx->queue_num;
905	struct blkfront_info *info = hctx->queue->queuedata;
906	struct blkfront_ring_info *rinfo = NULL;
907
908	rinfo = get_rinfo(info, i: qid);
909	blk_mq_start_request(rq: qd->rq);
910	spin_lock_irqsave(&rinfo->ring_lock, flags);
911	if (RING_FULL(&rinfo->ring))
912	goto out_busy;
913
914	if (blkif_request_flush_invalid(req: qd->rq, info: rinfo->dev_info))
915	goto out_err;
916
917	if (blkif_queue_request(req: qd->rq, rinfo))
918	goto out_busy;
919
920	flush_requests(rinfo);
921	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
922	return BLK_STS_OK;
923
924	out_err:
925	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
926	return BLK_STS_IOERR;
927
928	out_busy:
929	blk_mq_stop_hw_queue(hctx);
930	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
931	return BLK_STS_DEV_RESOURCE;
932	}
933
934	static void blkif_complete_rq(struct request *rq)
935	{
936	blk_mq_end_request(rq, error: blkif_req(rq)->error);
937	}
938
939	static const struct blk_mq_ops blkfront_mq_ops = {
940	.queue_rq = blkif_queue_rq,
941	.complete = blkif_complete_rq,
942	};
943
944	static void blkif_set_queue_limits(const struct blkfront_info *info,
945	struct queue_limits *lim)
946	{
947	unsigned int segments = info->max_indirect_segments ? :
948	BLKIF_MAX_SEGMENTS_PER_REQUEST;
949
950	if (info->feature_discard) {
951	lim->max_hw_discard_sectors = UINT_MAX;
952	if (info->discard_granularity)
953	lim->discard_granularity = info->discard_granularity;
954	lim->discard_alignment = info->discard_alignment;
955	if (info->feature_secdiscard)
956	lim->max_secure_erase_sectors = UINT_MAX;
957	}
958
959	/* Hard sector size and max sectors impersonate the equiv. hardware. */
960	lim->logical_block_size = info->sector_size;
961	lim->physical_block_size = info->physical_sector_size;
962	lim->max_hw_sectors = (segments * XEN_PAGE_SIZE) / 512;
963
964	/* Each segment in a request is up to an aligned page in size. */
965	lim->seg_boundary_mask = PAGE_SIZE - 1;
966	lim->max_segment_size = PAGE_SIZE;
967
968	/* Ensure a merged request will fit in a single I/O ring slot. */
969	lim->max_segments = segments / GRANTS_PER_PSEG;
970
971	/* Make sure buffer addresses are sector-aligned. */
972	lim->dma_alignment = 511;
973	}
974
975	static const char *flush_info(struct blkfront_info *info)
976	{
977	if (info->feature_flush && info->feature_fua)
978	return "barrier: enabled;";
979	else if (info->feature_flush)
980	return "flush diskcache: enabled;";
981	else
982	return "barrier or flush: disabled;";
983	}
984
985	static void xlvbd_flush(struct blkfront_info *info)
986	{
987	blk_queue_write_cache(q: info->rq, enabled: info->feature_flush ? true : false,
988	fua: info->feature_fua ? true : false);
989	pr_info("blkfront: %s: %s %s %s %s %s %s %s\n",
990	info->gd->disk_name, flush_info(info),
991	"persistent grants:", info->feature_persistent ?
992	"enabled;" : "disabled;", "indirect descriptors:",
993	info->max_indirect_segments ? "enabled;" : "disabled;",
994	"bounce buffer:", info->bounce ? "enabled" : "disabled;");
995	}
996
997	static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
998	{
999	int major;
1000	major = BLKIF_MAJOR(vdevice);
1001	*minor = BLKIF_MINOR(vdevice);
1002	switch (major) {
1003	case XEN_IDE0_MAJOR:
1004	*offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1005	*minor = ((*minor / 64) * PARTS_PER_DISK) +
1006	EMULATED_HD_DISK_MINOR_OFFSET;
1007	break;
1008	case XEN_IDE1_MAJOR:
1009	*offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1010	*minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1011	EMULATED_HD_DISK_MINOR_OFFSET;
1012	break;
1013	case XEN_SCSI_DISK0_MAJOR:
1014	*offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1015	*minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1016	break;
1017	case XEN_SCSI_DISK1_MAJOR:
1018	case XEN_SCSI_DISK2_MAJOR:
1019	case XEN_SCSI_DISK3_MAJOR:
1020	case XEN_SCSI_DISK4_MAJOR:
1021	case XEN_SCSI_DISK5_MAJOR:
1022	case XEN_SCSI_DISK6_MAJOR:
1023	case XEN_SCSI_DISK7_MAJOR:
1024	*offset = (*minor / PARTS_PER_DISK) +
1025	((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1026	EMULATED_SD_DISK_NAME_OFFSET;
1027	*minor = *minor +
1028	((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1029	EMULATED_SD_DISK_MINOR_OFFSET;
1030	break;
1031	case XEN_SCSI_DISK8_MAJOR:
1032	case XEN_SCSI_DISK9_MAJOR:
1033	case XEN_SCSI_DISK10_MAJOR:
1034	case XEN_SCSI_DISK11_MAJOR:
1035	case XEN_SCSI_DISK12_MAJOR:
1036	case XEN_SCSI_DISK13_MAJOR:
1037	case XEN_SCSI_DISK14_MAJOR:
1038	case XEN_SCSI_DISK15_MAJOR:
1039	*offset = (*minor / PARTS_PER_DISK) +
1040	((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1041	EMULATED_SD_DISK_NAME_OFFSET;
1042	*minor = *minor +
1043	((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1044	EMULATED_SD_DISK_MINOR_OFFSET;
1045	break;
1046	case XENVBD_MAJOR:
1047	*offset = *minor / PARTS_PER_DISK;
1048	break;
1049	default:
1050	printk(KERN_WARNING "blkfront: your disk configuration is "
1051	"incorrect, please use an xvd device instead\n");
1052	return -ENODEV;
1053	}
1054	return 0;
1055	}
1056
1057	static char *encode_disk_name(char *ptr, unsigned int n)
1058	{
1059	if (n >= 26)
1060	ptr = encode_disk_name(ptr, n: n / 26 - 1);
1061	*ptr = 'a' + n % 26;
1062	return ptr + 1;
1063	}
1064
1065	static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1066	struct blkfront_info *info, u16 sector_size,
1067	unsigned int physical_sector_size)
1068	{
1069	struct queue_limits lim = {};
1070	struct gendisk *gd;
1071	int nr_minors = 1;
1072	int err;
1073	unsigned int offset;
1074	int minor;
1075	int nr_parts;
1076	char *ptr;
1077
1078	BUG_ON(info->gd != NULL);
1079	BUG_ON(info->rq != NULL);
1080
1081	if ((info->vdevice>>EXT_SHIFT) > 1) {
1082	/* this is above the extended range; something is wrong */
1083	printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1084	return -ENODEV;
1085	}
1086
1087	if (!VDEV_IS_EXTENDED(info->vdevice)) {
1088	err = xen_translate_vdev(vdevice: info->vdevice, minor: &minor, offset: &offset);
1089	if (err)
1090	return err;
1091	nr_parts = PARTS_PER_DISK;
1092	} else {
1093	minor = BLKIF_MINOR_EXT(info->vdevice);
1094	nr_parts = PARTS_PER_EXT_DISK;
1095	offset = minor / nr_parts;
1096	if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1097	printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1098	"emulated IDE disks,\n\t choose an xvd device name"
1099	"from xvde on\n", info->vdevice);
1100	}
1101	if (minor >> MINORBITS) {
1102	pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1103	info->vdevice, minor);
1104	return -ENODEV;
1105	}
1106
1107	if ((minor % nr_parts) == 0)
1108	nr_minors = nr_parts;
1109
1110	err = xlbd_reserve_minors(minor, nr: nr_minors);
1111	if (err)
1112	return err;
1113
1114	memset(&info->tag_set, 0, sizeof(info->tag_set));
1115	info->tag_set.ops = &blkfront_mq_ops;
1116	info->tag_set.nr_hw_queues = info->nr_rings;
1117	if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
1118	/*
1119	* When indirect descriptior is not supported, the I/O request
1120	* will be split between multiple request in the ring.
1121	* To avoid problems when sending the request, divide by
1122	* 2 the depth of the queue.
1123	*/
1124	info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
1125	} else
1126	info->tag_set.queue_depth = BLK_RING_SIZE(info);
1127	info->tag_set.numa_node = NUMA_NO_NODE;
1128	info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1129	info->tag_set.cmd_size = sizeof(struct blkif_req);
1130	info->tag_set.driver_data = info;
1131
1132	err = blk_mq_alloc_tag_set(set: &info->tag_set);
1133	if (err)
1134	goto out_release_minors;
1135
1136	blkif_set_queue_limits(info, lim: &lim);
1137	gd = blk_mq_alloc_disk(&info->tag_set, &lim, info);
1138	if (IS_ERR(ptr: gd)) {
1139	err = PTR_ERR(ptr: gd);
1140	goto out_free_tag_set;
1141	}
1142	blk_queue_flag_set(QUEUE_FLAG_VIRT, q: gd->queue);
1143
1144	strcpy(p: gd->disk_name, DEV_NAME);
1145	ptr = encode_disk_name(ptr: gd->disk_name + sizeof(DEV_NAME) - 1, n: offset);
1146	BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1147	if (nr_minors > 1)
1148	*ptr = 0;
1149	else
1150	snprintf(buf: ptr, size: gd->disk_name + DISK_NAME_LEN - ptr,
1151	fmt: "%d", minor & (nr_parts - 1));
1152
1153	gd->major = XENVBD_MAJOR;
1154	gd->first_minor = minor;
1155	gd->minors = nr_minors;
1156	gd->fops = &xlvbd_block_fops;
1157	gd->private_data = info;
1158	set_capacity(disk: gd, size: capacity);
1159
1160	info->rq = gd->queue;
1161	info->gd = gd;
1162	info->sector_size = sector_size;
1163	info->physical_sector_size = physical_sector_size;
1164
1165	xlvbd_flush(info);
1166
1167	if (info->vdisk_info & VDISK_READONLY)
1168	set_disk_ro(disk: gd, read_only: 1);
1169	if (info->vdisk_info & VDISK_REMOVABLE)
1170	gd->flags |= GENHD_FL_REMOVABLE;
1171
1172	return 0;
1173
1174	out_free_tag_set:
1175	blk_mq_free_tag_set(set: &info->tag_set);
1176	out_release_minors:
1177	xlbd_release_minors(minor, nr: nr_minors);
1178	return err;
1179	}
1180
1181	/* Already hold rinfo->ring_lock. */
1182	static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1183	{
1184	if (!RING_FULL(&rinfo->ring))
1185	blk_mq_start_stopped_hw_queues(q: rinfo->dev_info->rq, async: true);
1186	}
1187
1188	static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1189	{
1190	unsigned long flags;
1191
1192	spin_lock_irqsave(&rinfo->ring_lock, flags);
1193	kick_pending_request_queues_locked(rinfo);
1194	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
1195	}
1196
1197	static void blkif_restart_queue(struct work_struct *work)
1198	{
1199	struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1200
1201	if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1202	kick_pending_request_queues(rinfo);
1203	}
1204
1205	static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1206	{
1207	struct grant *persistent_gnt, *n;
1208	struct blkfront_info *info = rinfo->dev_info;
1209	int i, j, segs;
1210
1211	/*
1212	* Remove indirect pages, this only happens when using indirect
1213	* descriptors but not persistent grants
1214	*/
1215	if (!list_empty(head: &rinfo->indirect_pages)) {
1216	struct page *indirect_page, *n;
1217
1218	BUG_ON(info->bounce);
1219	list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1220	list_del(entry: &indirect_page->lru);
1221	__free_page(indirect_page);
1222	}
1223	}
1224
1225	/* Remove all persistent grants. */
1226	if (!list_empty(head: &rinfo->grants)) {
1227	list_for_each_entry_safe(persistent_gnt, n,
1228	&rinfo->grants, node) {
1229	list_del(entry: &persistent_gnt->node);
1230	if (persistent_gnt->gref != INVALID_GRANT_REF) {
1231	gnttab_end_foreign_access(ref: persistent_gnt->gref,
1232	NULL);
1233	rinfo->persistent_gnts_c--;
1234	}
1235	if (info->bounce)
1236	__free_page(persistent_gnt->page);
1237	kfree(objp: persistent_gnt);
1238	}
1239	}
1240	BUG_ON(rinfo->persistent_gnts_c != 0);
1241
1242	for (i = 0; i < BLK_RING_SIZE(info); i++) {
1243	/*
1244	* Clear persistent grants present in requests already
1245	* on the shared ring
1246	*/
1247	if (!rinfo->shadow[i].request)
1248	goto free_shadow;
1249
1250	segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1251	rinfo->shadow[i].req.u.indirect.nr_segments :
1252	rinfo->shadow[i].req.u.rw.nr_segments;
1253	for (j = 0; j < segs; j++) {
1254	persistent_gnt = rinfo->shadow[i].grants_used[j];
1255	gnttab_end_foreign_access(ref: persistent_gnt->gref, NULL);
1256	if (info->bounce)
1257	__free_page(persistent_gnt->page);
1258	kfree(objp: persistent_gnt);
1259	}
1260
1261	if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1262	/*
1263	* If this is not an indirect operation don't try to
1264	* free indirect segments
1265	*/
1266	goto free_shadow;
1267
1268	for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1269	persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1270	gnttab_end_foreign_access(ref: persistent_gnt->gref, NULL);
1271	__free_page(persistent_gnt->page);
1272	kfree(objp: persistent_gnt);
1273	}
1274
1275	free_shadow:
1276	kvfree(addr: rinfo->shadow[i].grants_used);
1277	rinfo->shadow[i].grants_used = NULL;
1278	kvfree(addr: rinfo->shadow[i].indirect_grants);
1279	rinfo->shadow[i].indirect_grants = NULL;
1280	kvfree(addr: rinfo->shadow[i].sg);
1281	rinfo->shadow[i].sg = NULL;
1282	}
1283
1284	/* No more gnttab callback work. */
1285	gnttab_cancel_free_callback(callback: &rinfo->callback);
1286
1287	/* Flush gnttab callback work. Must be done with no locks held. */
1288	flush_work(work: &rinfo->work);
1289
1290	/* Free resources associated with old device channel. */
1291	xenbus_teardown_ring(vaddr: (void **)&rinfo->ring.sring, nr_pages: info->nr_ring_pages,
1292	grefs: rinfo->ring_ref);
1293
1294	if (rinfo->irq)
1295	unbind_from_irqhandler(irq: rinfo->irq, dev_id: rinfo);
1296	rinfo->evtchn = rinfo->irq = 0;
1297	}
1298
1299	static void blkif_free(struct blkfront_info *info, int suspend)
1300	{
1301	unsigned int i;
1302	struct blkfront_ring_info *rinfo;
1303
1304	/* Prevent new requests being issued until we fix things up. */
1305	info->connected = suspend ?
1306	BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1307	/* No more blkif_request(). */
1308	if (info->rq)
1309	blk_mq_stop_hw_queues(q: info->rq);
1310
1311	for_each_rinfo(info, rinfo, i)
1312	blkif_free_ring(rinfo);
1313
1314	kvfree(addr: info->rinfo);
1315	info->rinfo = NULL;
1316	info->nr_rings = 0;
1317	}
1318
1319	struct copy_from_grant {
1320	const struct blk_shadow *s;
1321	unsigned int grant_idx;
1322	unsigned int bvec_offset;
1323	char *bvec_data;
1324	};
1325
1326	static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1327	unsigned int len, void *data)
1328	{
1329	struct copy_from_grant *info = data;
1330	char *shared_data;
1331	/* Convenient aliases */
1332	const struct blk_shadow *s = info->s;
1333
1334	shared_data = kmap_atomic(page: s->grants_used[info->grant_idx]->page);
1335
1336	memcpy(info->bvec_data + info->bvec_offset,
1337	shared_data + offset, len);
1338
1339	info->bvec_offset += len;
1340	info->grant_idx++;
1341
1342	kunmap_atomic(shared_data);
1343	}
1344
1345	static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1346	{
1347	switch (rsp)
1348	{
1349	case BLKIF_RSP_OKAY:
1350	return REQ_DONE;
1351	case BLKIF_RSP_EOPNOTSUPP:
1352	return REQ_EOPNOTSUPP;
1353	case BLKIF_RSP_ERROR:
1354	default:
1355	return REQ_ERROR;
1356	}
1357	}
1358
1359	/*
1360	* Get the final status of the block request based on two ring response
1361	*/
1362	static int blkif_get_final_status(enum blk_req_status s1,
1363	enum blk_req_status s2)
1364	{
1365	BUG_ON(s1 < REQ_DONE);
1366	BUG_ON(s2 < REQ_DONE);
1367
1368	if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1369	return BLKIF_RSP_ERROR;
1370	else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1371	return BLKIF_RSP_EOPNOTSUPP;
1372	return BLKIF_RSP_OKAY;
1373	}
1374
1375	/*
1376	* Return values:
1377	* 1 response processed.
1378	* 0 missing further responses.
1379	* -1 error while processing.
1380	*/
1381	static int blkif_completion(unsigned long *id,
1382	struct blkfront_ring_info *rinfo,
1383	struct blkif_response *bret)
1384	{
1385	int i = 0;
1386	struct scatterlist *sg;
1387	int num_sg, num_grant;
1388	struct blkfront_info *info = rinfo->dev_info;
1389	struct blk_shadow *s = &rinfo->shadow[*id];
1390	struct copy_from_grant data = {
1391	.grant_idx = 0,
1392	};
1393
1394	num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1395	s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1396
1397	/* The I/O request may be split in two. */
1398	if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1399	struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1400
1401	/* Keep the status of the current response in shadow. */
1402	s->status = blkif_rsp_to_req_status(rsp: bret->status);
1403
1404	/* Wait the second response if not yet here. */
1405	if (s2->status < REQ_DONE)
1406	return 0;
1407
1408	bret->status = blkif_get_final_status(s1: s->status,
1409	s2: s2->status);
1410
1411	/*
1412	* All the grants is stored in the first shadow in order
1413	* to make the completion code simpler.
1414	*/
1415	num_grant += s2->req.u.rw.nr_segments;
1416
1417	/*
1418	* The two responses may not come in order. Only the
1419	* first request will store the scatter-gather list.
1420	*/
1421	if (s2->num_sg != 0) {
1422	/* Update "id" with the ID of the first response. */
1423	*id = s->associated_id;
1424	s = s2;
1425	}
1426
1427	/*
1428	* We don't need anymore the second request, so recycling
1429	* it now.
1430	*/
1431	if (add_id_to_freelist(rinfo, id: s->associated_id))
1432	WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1433	info->gd->disk_name, s->associated_id);
1434	}
1435
1436	data.s = s;
1437	num_sg = s->num_sg;
1438
1439	if (bret->operation == BLKIF_OP_READ && info->bounce) {
1440	for_each_sg(s->sg, sg, num_sg, i) {
1441	BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1442
1443	data.bvec_offset = sg->offset;
1444	data.bvec_data = kmap_atomic(page: sg_page(sg));
1445
1446	gnttab_foreach_grant_in_range(page: sg_page(sg),
1447	offset: sg->offset,
1448	len: sg->length,
1449	fn: blkif_copy_from_grant,
1450	data: &data);
1451
1452	kunmap_atomic(data.bvec_data);
1453	}
1454	}
1455	/* Add the persistent grant into the list of free grants */
1456	for (i = 0; i < num_grant; i++) {
1457	if (!gnttab_try_end_foreign_access(ref: s->grants_used[i]->gref)) {
1458	/*
1459	* If the grant is still mapped by the backend (the
1460	* backend has chosen to make this grant persistent)
1461	* we add it at the head of the list, so it will be
1462	* reused first.
1463	*/
1464	if (!info->feature_persistent) {
1465	pr_alert("backed has not unmapped grant: %u\n",
1466	s->grants_used[i]->gref);
1467	return -1;
1468	}
1469	list_add(new: &s->grants_used[i]->node, head: &rinfo->grants);
1470	rinfo->persistent_gnts_c++;
1471	} else {
1472	/*
1473	* If the grant is not mapped by the backend we add it
1474	* to the tail of the list, so it will not be picked
1475	* again unless we run out of persistent grants.
1476	*/
1477	s->grants_used[i]->gref = INVALID_GRANT_REF;
1478	list_add_tail(new: &s->grants_used[i]->node, head: &rinfo->grants);
1479	}
1480	}
1481	if (s->req.operation == BLKIF_OP_INDIRECT) {
1482	for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1483	if (!gnttab_try_end_foreign_access(ref: s->indirect_grants[i]->gref)) {
1484	if (!info->feature_persistent) {
1485	pr_alert("backed has not unmapped grant: %u\n",
1486	s->indirect_grants[i]->gref);
1487	return -1;
1488	}
1489	list_add(new: &s->indirect_grants[i]->node, head: &rinfo->grants);
1490	rinfo->persistent_gnts_c++;
1491	} else {
1492	struct page *indirect_page;
1493
1494	/*
1495	* Add the used indirect page back to the list of
1496	* available pages for indirect grefs.
1497	*/
1498	if (!info->bounce) {
1499	indirect_page = s->indirect_grants[i]->page;
1500	list_add(new: &indirect_page->lru, head: &rinfo->indirect_pages);
1501	}
1502	s->indirect_grants[i]->gref = INVALID_GRANT_REF;
1503	list_add_tail(new: &s->indirect_grants[i]->node, head: &rinfo->grants);
1504	}
1505	}
1506	}
1507
1508	return 1;
1509	}
1510
1511	static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1512	{
1513	struct request *req;
1514	struct blkif_response bret;
1515	RING_IDX i, rp;
1516	unsigned long flags;
1517	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1518	struct blkfront_info *info = rinfo->dev_info;
1519	unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
1520
1521	if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1522	xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
1523	return IRQ_HANDLED;
1524	}
1525
1526	spin_lock_irqsave(&rinfo->ring_lock, flags);
1527	again:
1528	rp = READ_ONCE(rinfo->ring.sring->rsp_prod);
1529	virt_rmb(); /* Ensure we see queued responses up to 'rp'. */
1530	if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) {
1531	pr_alert("%s: illegal number of responses %u\n",
1532	info->gd->disk_name, rp - rinfo->ring.rsp_cons);
1533	goto err;
1534	}
1535
1536	for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1537	unsigned long id;
1538	unsigned int op;
1539
1540	eoiflag = 0;
1541
1542	RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
1543	id = bret.id;
1544
1545	/*
1546	* The backend has messed up and given us an id that we would
1547	* never have given to it (we stamp it up to BLK_RING_SIZE -
1548	* look in get_id_from_freelist.
1549	*/
1550	if (id >= BLK_RING_SIZE(info)) {
1551	pr_alert("%s: response has incorrect id (%ld)\n",
1552	info->gd->disk_name, id);
1553	goto err;
1554	}
1555	if (rinfo->shadow[id].status != REQ_WAITING) {
1556	pr_alert("%s: response references no pending request\n",
1557	info->gd->disk_name);
1558	goto err;
1559	}
1560
1561	rinfo->shadow[id].status = REQ_PROCESSING;
1562	req = rinfo->shadow[id].request;
1563
1564	op = rinfo->shadow[id].req.operation;
1565	if (op == BLKIF_OP_INDIRECT)
1566	op = rinfo->shadow[id].req.u.indirect.indirect_op;
1567	if (bret.operation != op) {
1568	pr_alert("%s: response has wrong operation (%u instead of %u)\n",
1569	info->gd->disk_name, bret.operation, op);
1570	goto err;
1571	}
1572
1573	if (bret.operation != BLKIF_OP_DISCARD) {
1574	int ret;
1575
1576	/*
1577	* We may need to wait for an extra response if the
1578	* I/O request is split in 2
1579	*/
1580	ret = blkif_completion(id: &id, rinfo, bret: &bret);
1581	if (!ret)
1582	continue;
1583	if (unlikely(ret < 0))
1584	goto err;
1585	}
1586
1587	if (add_id_to_freelist(rinfo, id)) {
1588	WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1589	info->gd->disk_name, op_name(bret.operation), id);
1590	continue;
1591	}
1592
1593	if (bret.status == BLKIF_RSP_OKAY)
1594	blkif_req(rq: req)->error = BLK_STS_OK;
1595	else
1596	blkif_req(rq: req)->error = BLK_STS_IOERR;
1597
1598	switch (bret.operation) {
1599	case BLKIF_OP_DISCARD:
1600	if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1601	struct request_queue *rq = info->rq;
1602
1603	pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1604	info->gd->disk_name, op_name(bret.operation));
1605	blkif_req(rq: req)->error = BLK_STS_NOTSUPP;
1606	info->feature_discard = 0;
1607	info->feature_secdiscard = 0;
1608	blk_queue_max_discard_sectors(q: rq, max_discard_sectors: 0);
1609	blk_queue_max_secure_erase_sectors(q: rq, max_sectors: 0);
1610	}
1611	break;
1612	case BLKIF_OP_FLUSH_DISKCACHE:
1613	case BLKIF_OP_WRITE_BARRIER:
1614	if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1615	pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1616	info->gd->disk_name, op_name(bret.operation));
1617	blkif_req(rq: req)->error = BLK_STS_NOTSUPP;
1618	}
1619	if (unlikely(bret.status == BLKIF_RSP_ERROR &&
1620	rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1621	pr_warn_ratelimited("blkfront: %s: empty %s op failed\n",
1622	info->gd->disk_name, op_name(bret.operation));
1623	blkif_req(rq: req)->error = BLK_STS_NOTSUPP;
1624	}
1625	if (unlikely(blkif_req(req)->error)) {
1626	if (blkif_req(rq: req)->error == BLK_STS_NOTSUPP)
1627	blkif_req(rq: req)->error = BLK_STS_OK;
1628	info->feature_fua = 0;
1629	info->feature_flush = 0;
1630	xlvbd_flush(info);
1631	}
1632	fallthrough;
1633	case BLKIF_OP_READ:
1634	case BLKIF_OP_WRITE:
1635	if (unlikely(bret.status != BLKIF_RSP_OKAY))
1636	dev_dbg_ratelimited(&info->xbdev->dev,
1637	"Bad return from blkdev data request: %#x\n",
1638	bret.status);
1639
1640	break;
1641	default:
1642	BUG();
1643	}
1644
1645	if (likely(!blk_should_fake_timeout(req->q)))
1646	blk_mq_complete_request(rq: req);
1647	}
1648
1649	rinfo->ring.rsp_cons = i;
1650
1651	if (i != rinfo->ring.req_prod_pvt) {
1652	int more_to_do;
1653	RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1654	if (more_to_do)
1655	goto again;
1656	} else
1657	rinfo->ring.sring->rsp_event = i + 1;
1658
1659	kick_pending_request_queues_locked(rinfo);
1660
1661	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
1662
1663	xen_irq_lateeoi(irq, eoi_flags: eoiflag);
1664
1665	return IRQ_HANDLED;
1666
1667	err:
1668	info->connected = BLKIF_STATE_ERROR;
1669
1670	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
1671
1672	/* No EOI in order to avoid further interrupts. */
1673
1674	pr_alert("%s disabled for further use\n", info->gd->disk_name);
1675	return IRQ_HANDLED;
1676	}
1677
1678
1679	static int setup_blkring(struct xenbus_device *dev,
1680	struct blkfront_ring_info *rinfo)
1681	{
1682	struct blkif_sring *sring;
1683	int err;
1684	struct blkfront_info *info = rinfo->dev_info;
1685	unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1686
1687	err = xenbus_setup_ring(dev, GFP_NOIO, vaddr: (void **)&sring,
1688	nr_pages: info->nr_ring_pages, grefs: rinfo->ring_ref);
1689	if (err)
1690	goto fail;
1691
1692	XEN_FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1693
1694	err = xenbus_alloc_evtchn(dev, port: &rinfo->evtchn);
1695	if (err)
1696	goto fail;
1697
1698	err = bind_evtchn_to_irqhandler_lateeoi(evtchn: rinfo->evtchn, handler: blkif_interrupt,
1699	irqflags: 0, devname: "blkif", dev_id: rinfo);
1700	if (err <= 0) {
1701	xenbus_dev_fatal(dev, err,
1702	fmt: "bind_evtchn_to_irqhandler failed");
1703	goto fail;
1704	}
1705	rinfo->irq = err;
1706
1707	return 0;
1708	fail:
1709	blkif_free(info, suspend: 0);
1710	return err;
1711	}
1712
1713	/*
1714	* Write out per-ring/queue nodes including ring-ref and event-channel, and each
1715	* ring buffer may have multi pages depending on ->nr_ring_pages.
1716	*/
1717	static int write_per_ring_nodes(struct xenbus_transaction xbt,
1718	struct blkfront_ring_info *rinfo, const char *dir)
1719	{
1720	int err;
1721	unsigned int i;
1722	const char *message = NULL;
1723	struct blkfront_info *info = rinfo->dev_info;
1724
1725	if (info->nr_ring_pages == 1) {
1726	err = xenbus_printf(t: xbt, dir, node: "ring-ref", fmt: "%u", rinfo->ring_ref[0]);
1727	if (err) {
1728	message = "writing ring-ref";
1729	goto abort_transaction;
1730	}
1731	} else {
1732	for (i = 0; i < info->nr_ring_pages; i++) {
1733	char ring_ref_name[RINGREF_NAME_LEN];
1734
1735	snprintf(buf: ring_ref_name, RINGREF_NAME_LEN, fmt: "ring-ref%u", i);
1736	err = xenbus_printf(t: xbt, dir, node: ring_ref_name,
1737	fmt: "%u", rinfo->ring_ref[i]);
1738	if (err) {
1739	message = "writing ring-ref";
1740	goto abort_transaction;
1741	}
1742	}
1743	}
1744
1745	err = xenbus_printf(t: xbt, dir, node: "event-channel", fmt: "%u", rinfo->evtchn);
1746	if (err) {
1747	message = "writing event-channel";
1748	goto abort_transaction;
1749	}
1750
1751	return 0;
1752
1753	abort_transaction:
1754	xenbus_transaction_end(t: xbt, abort: 1);
1755	if (message)
1756	xenbus_dev_fatal(dev: info->xbdev, err, fmt: "%s", message);
1757
1758	return err;
1759	}
1760
1761	/* Enable the persistent grants feature. */
1762	static bool feature_persistent = true;
1763	module_param(feature_persistent, bool, 0644);
1764	MODULE_PARM_DESC(feature_persistent,
1765	"Enables the persistent grants feature");
1766
1767	/* Common code used when first setting up, and when resuming. */
1768	static int talk_to_blkback(struct xenbus_device *dev,
1769	struct blkfront_info *info)
1770	{
1771	const char *message = NULL;
1772	struct xenbus_transaction xbt;
1773	int err;
1774	unsigned int i, max_page_order;
1775	unsigned int ring_page_order;
1776	struct blkfront_ring_info *rinfo;
1777
1778	if (!info)
1779	return -ENODEV;
1780
1781	/* Check if backend is trusted. */
1782	info->bounce = !xen_blkif_trusted ||
1783	!xenbus_read_unsigned(dir: dev->nodename, node: "trusted", default_val: 1);
1784
1785	max_page_order = xenbus_read_unsigned(dir: info->xbdev->otherend,
1786	node: "max-ring-page-order", default_val: 0);
1787	ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1788	info->nr_ring_pages = 1 << ring_page_order;
1789
1790	err = negotiate_mq(info);
1791	if (err)
1792	goto destroy_blkring;
1793
1794	for_each_rinfo(info, rinfo, i) {
1795	/* Create shared ring, alloc event channel. */
1796	err = setup_blkring(dev, rinfo);
1797	if (err)
1798	goto destroy_blkring;
1799	}
1800
1801	again:
1802	err = xenbus_transaction_start(t: &xbt);
1803	if (err) {
1804	xenbus_dev_fatal(dev, err, fmt: "starting transaction");
1805	goto destroy_blkring;
1806	}
1807
1808	if (info->nr_ring_pages > 1) {
1809	err = xenbus_printf(t: xbt, dir: dev->nodename, node: "ring-page-order", fmt: "%u",
1810	ring_page_order);
1811	if (err) {
1812	message = "writing ring-page-order";
1813	goto abort_transaction;
1814	}
1815	}
1816
1817	/* We already got the number of queues/rings in _probe */
1818	if (info->nr_rings == 1) {
1819	err = write_per_ring_nodes(xbt, rinfo: info->rinfo, dir: dev->nodename);
1820	if (err)
1821	goto destroy_blkring;
1822	} else {
1823	char *path;
1824	size_t pathsize;
1825
1826	err = xenbus_printf(t: xbt, dir: dev->nodename, node: "multi-queue-num-queues", fmt: "%u",
1827	info->nr_rings);
1828	if (err) {
1829	message = "writing multi-queue-num-queues";
1830	goto abort_transaction;
1831	}
1832
1833	pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1834	path = kmalloc(size: pathsize, GFP_KERNEL);
1835	if (!path) {
1836	err = -ENOMEM;
1837	message = "ENOMEM while writing ring references";
1838	goto abort_transaction;
1839	}
1840
1841	for_each_rinfo(info, rinfo, i) {
1842	memset(path, 0, pathsize);
1843	snprintf(buf: path, size: pathsize, fmt: "%s/queue-%u", dev->nodename, i);
1844	err = write_per_ring_nodes(xbt, rinfo, dir: path);
1845	if (err) {
1846	kfree(objp: path);
1847	goto destroy_blkring;
1848	}
1849	}
1850	kfree(objp: path);
1851	}
1852	err = xenbus_printf(t: xbt, dir: dev->nodename, node: "protocol", fmt: "%s",
1853	XEN_IO_PROTO_ABI_NATIVE);
1854	if (err) {
1855	message = "writing protocol";
1856	goto abort_transaction;
1857	}
1858	info->feature_persistent_parm = feature_persistent;
1859	err = xenbus_printf(t: xbt, dir: dev->nodename, node: "feature-persistent", fmt: "%u",
1860	info->feature_persistent_parm);
1861	if (err)
1862	dev_warn(&dev->dev,
1863	"writing persistent grants feature to xenbus");
1864
1865	err = xenbus_transaction_end(t: xbt, abort: 0);
1866	if (err) {
1867	if (err == -EAGAIN)
1868	goto again;
1869	xenbus_dev_fatal(dev, err, fmt: "completing transaction");
1870	goto destroy_blkring;
1871	}
1872
1873	for_each_rinfo(info, rinfo, i) {
1874	unsigned int j;
1875
1876	for (j = 0; j < BLK_RING_SIZE(info); j++)
1877	rinfo->shadow[j].req.u.rw.id = j + 1;
1878	rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1879	}
1880	xenbus_switch_state(dev, new_state: XenbusStateInitialised);
1881
1882	return 0;
1883
1884	abort_transaction:
1885	xenbus_transaction_end(t: xbt, abort: 1);
1886	if (message)
1887	xenbus_dev_fatal(dev, err, fmt: "%s", message);
1888	destroy_blkring:
1889	blkif_free(info, suspend: 0);
1890	return err;
1891	}
1892
1893	static int negotiate_mq(struct blkfront_info *info)
1894	{
1895	unsigned int backend_max_queues;
1896	unsigned int i;
1897	struct blkfront_ring_info *rinfo;
1898
1899	BUG_ON(info->nr_rings);
1900
1901	/* Check if backend supports multiple queues. */
1902	backend_max_queues = xenbus_read_unsigned(dir: info->xbdev->otherend,
1903	node: "multi-queue-max-queues", default_val: 1);
1904	info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1905	/* We need at least one ring. */
1906	if (!info->nr_rings)
1907	info->nr_rings = 1;
1908
1909	info->rinfo_size = struct_size(info->rinfo, shadow,
1910	BLK_RING_SIZE(info));
1911	info->rinfo = kvcalloc(n: info->nr_rings, size: info->rinfo_size, GFP_KERNEL);
1912	if (!info->rinfo) {
1913	xenbus_dev_fatal(dev: info->xbdev, err: -ENOMEM, fmt: "allocating ring_info structure");
1914	info->nr_rings = 0;
1915	return -ENOMEM;
1916	}
1917
1918	for_each_rinfo(info, rinfo, i) {
1919	INIT_LIST_HEAD(list: &rinfo->indirect_pages);
1920	INIT_LIST_HEAD(list: &rinfo->grants);
1921	rinfo->dev_info = info;
1922	INIT_WORK(&rinfo->work, blkif_restart_queue);
1923	spin_lock_init(&rinfo->ring_lock);
1924	}
1925	return 0;
1926	}
1927
1928	/*
1929	* Entry point to this code when a new device is created. Allocate the basic
1930	* structures and the ring buffer for communication with the backend, and
1931	* inform the backend of the appropriate details for those. Switch to
1932	* Initialised state.
1933	*/
1934	static int blkfront_probe(struct xenbus_device *dev,
1935	const struct xenbus_device_id *id)
1936	{
1937	int err, vdevice;
1938	struct blkfront_info *info;
1939
1940	/* FIXME: Use dynamic device id if this is not set. */
1941	err = xenbus_scanf(XBT_NIL, dir: dev->nodename,
1942	node: "virtual-device", fmt: "%i", &vdevice);
1943	if (err != 1) {
1944	/* go looking in the extended area instead */
1945	err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1946	"%i", &vdevice);
1947	if (err != 1) {
1948	xenbus_dev_fatal(dev, err, "reading virtual-device");
1949	return err;
1950	}
1951	}
1952
1953	if (xen_hvm_domain()) {
1954	char *type;
1955	int len;
1956	/* no unplug has been done: do not hook devices != xen vbds */
1957	if (xen_has_pv_and_legacy_disk_devices()) {
1958	int major;
1959
1960	if (!VDEV_IS_EXTENDED(vdevice))
1961	major = BLKIF_MAJOR(vdevice);
1962	else
1963	major = XENVBD_MAJOR;
1964
1965	if (major != XENVBD_MAJOR) {
1966	printk(KERN_INFO
1967	"%s: HVM does not support vbd %d as xen block device\n",
1968	__func__, vdevice);
1969	return -ENODEV;
1970	}
1971	}
1972	/* do not create a PV cdrom device if we are an HVM guest */
1973	type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1974	if (IS_ERR(type))
1975	return -ENODEV;
1976	if (strncmp(type, "cdrom", 5) == 0) {
1977	kfree(type);
1978	return -ENODEV;
1979	}
1980	kfree(type);
1981	}
1982	info = kzalloc(sizeof(*info), GFP_KERNEL);
1983	if (!info) {
1984	xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1985	return -ENOMEM;
1986	}
1987
1988	info->xbdev = dev;
1989
1990	mutex_init(&info->mutex);
1991	info->vdevice = vdevice;
1992	info->connected = BLKIF_STATE_DISCONNECTED;
1993
1994	/* Front end dir is a number, which is used as the id. */
1995	info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1996	dev_set_drvdata(&dev->dev, info);
1997
1998	mutex_lock(&blkfront_mutex);
1999	list_add(&info->info_list, &info_list);
2000	mutex_unlock(&blkfront_mutex);
2001
2002	return 0;
2003	}
2004
2005	static int blkif_recover(struct blkfront_info *info)
2006	{
2007	struct queue_limits lim;
2008	unsigned int r_index;
2009	struct request *req, *n;
2010	int rc;
2011	struct bio *bio;
2012	struct blkfront_ring_info *rinfo;
2013
2014	lim = queue_limits_start_update(q: info->rq);
2015	blkfront_gather_backend_features(info);
2016	blkif_set_queue_limits(info, lim: &lim);
2017	rc = queue_limits_commit_update(q: info->rq, lim: &lim);
2018	if (rc)
2019	return rc;
2020
2021	for_each_rinfo(info, rinfo, r_index) {
2022	rc = blkfront_setup_indirect(rinfo);
2023	if (rc)
2024	return rc;
2025	}
2026	xenbus_switch_state(dev: info->xbdev, new_state: XenbusStateConnected);
2027
2028	/* Now safe for us to use the shared ring */
2029	info->connected = BLKIF_STATE_CONNECTED;
2030
2031	for_each_rinfo(info, rinfo, r_index) {
2032	/* Kick any other new requests queued since we resumed */
2033	kick_pending_request_queues(rinfo);
2034	}
2035
2036	list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2037	/* Requeue pending requests (flush or discard) */
2038	list_del_init(entry: &req->queuelist);
2039	BUG_ON(req->nr_phys_segments >
2040	(info->max_indirect_segments ? :
2041	BLKIF_MAX_SEGMENTS_PER_REQUEST));
2042	blk_mq_requeue_request(rq: req, kick_requeue_list: false);
2043	}
2044	blk_mq_start_stopped_hw_queues(q: info->rq, async: true);
2045	blk_mq_kick_requeue_list(q: info->rq);
2046
2047	while ((bio = bio_list_pop(bl: &info->bio_list)) != NULL) {
2048	/* Traverse the list of pending bios and re-queue them */
2049	submit_bio(bio);
2050	}
2051
2052	return 0;
2053	}
2054
2055	/*
2056	* We are reconnecting to the backend, due to a suspend/resume, or a backend
2057	* driver restart. We tear down our blkif structure and recreate it, but
2058	* leave the device-layer structures intact so that this is transparent to the
2059	* rest of the kernel.
2060	*/
2061	static int blkfront_resume(struct xenbus_device *dev)
2062	{
2063	struct blkfront_info *info = dev_get_drvdata(dev: &dev->dev);
2064	int err = 0;
2065	unsigned int i, j;
2066	struct blkfront_ring_info *rinfo;
2067
2068	dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2069
2070	bio_list_init(bl: &info->bio_list);
2071	INIT_LIST_HEAD(list: &info->requests);
2072	for_each_rinfo(info, rinfo, i) {
2073	struct bio_list merge_bio;
2074	struct blk_shadow *shadow = rinfo->shadow;
2075
2076	for (j = 0; j < BLK_RING_SIZE(info); j++) {
2077	/* Not in use? */
2078	if (!shadow[j].request)
2079	continue;
2080
2081	/*
2082	* Get the bios in the request so we can re-queue them.
2083	*/
2084	if (req_op(req: shadow[j].request) == REQ_OP_FLUSH ||
2085	req_op(req: shadow[j].request) == REQ_OP_DISCARD ||
2086	req_op(req: shadow[j].request) == REQ_OP_SECURE_ERASE ||
2087	shadow[j].request->cmd_flags & REQ_FUA) {
2088	/*
2089	* Flush operations don't contain bios, so
2090	* we need to requeue the whole request
2091	*
2092	* XXX: but this doesn't make any sense for a
2093	* write with the FUA flag set..
2094	*/
2095	list_add(new: &shadow[j].request->queuelist, head: &info->requests);
2096	continue;
2097	}
2098	merge_bio.head = shadow[j].request->bio;
2099	merge_bio.tail = shadow[j].request->biotail;
2100	bio_list_merge(bl: &info->bio_list, bl2: &merge_bio);
2101	shadow[j].request->bio = NULL;
2102	blk_mq_end_request(rq: shadow[j].request, BLK_STS_OK);
2103	}
2104	}
2105
2106	blkif_free(info, suspend: info->connected == BLKIF_STATE_CONNECTED);
2107
2108	err = talk_to_blkback(dev, info);
2109	if (!err)
2110	blk_mq_update_nr_hw_queues(set: &info->tag_set, nr_hw_queues: info->nr_rings);
2111
2112	/*
2113	* We have to wait for the backend to switch to
2114	* connected state, since we want to read which
2115	* features it supports.
2116	*/
2117
2118	return err;
2119	}
2120
2121	static void blkfront_closing(struct blkfront_info *info)
2122	{
2123	struct xenbus_device *xbdev = info->xbdev;
2124	struct blkfront_ring_info *rinfo;
2125	unsigned int i;
2126
2127	if (xbdev->state == XenbusStateClosing)
2128	return;
2129
2130	/* No more blkif_request(). */
2131	if (info->rq && info->gd) {
2132	blk_mq_stop_hw_queues(q: info->rq);
2133	blk_mark_disk_dead(disk: info->gd);
2134	}
2135
2136	for_each_rinfo(info, rinfo, i) {
2137	/* No more gnttab callback work. */
2138	gnttab_cancel_free_callback(callback: &rinfo->callback);
2139
2140	/* Flush gnttab callback work. Must be done with no locks held. */
2141	flush_work(work: &rinfo->work);
2142	}
2143
2144	xenbus_frontend_closed(dev: xbdev);
2145	}
2146
2147	static void blkfront_setup_discard(struct blkfront_info *info)
2148	{
2149	info->feature_discard = 1;
2150	info->discard_granularity = xenbus_read_unsigned(dir: info->xbdev->otherend,
2151	node: "discard-granularity",
2152	default_val: 0);
2153	info->discard_alignment = xenbus_read_unsigned(dir: info->xbdev->otherend,
2154	node: "discard-alignment", default_val: 0);
2155	info->feature_secdiscard =
2156	!!xenbus_read_unsigned(dir: info->xbdev->otherend, node: "discard-secure",
2157	default_val: 0);
2158	}
2159
2160	static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2161	{
2162	unsigned int psegs, grants, memflags;
2163	int err, i;
2164	struct blkfront_info *info = rinfo->dev_info;
2165
2166	memflags = memalloc_noio_save();
2167
2168	if (info->max_indirect_segments == 0) {
2169	if (!HAS_EXTRA_REQ)
2170	grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2171	else {
2172	/*
2173	* When an extra req is required, the maximum
2174	* grants supported is related to the size of the
2175	* Linux block segment.
2176	*/
2177	grants = GRANTS_PER_PSEG;
2178	}
2179	}
2180	else
2181	grants = info->max_indirect_segments;
2182	psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2183
2184	err = fill_grant_buffer(rinfo,
2185	num: (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2186	if (err)
2187	goto out_of_memory;
2188
2189	if (!info->bounce && info->max_indirect_segments) {
2190	/*
2191	* We are using indirect descriptors but don't have a bounce
2192	* buffer, we need to allocate a set of pages that can be
2193	* used for mapping indirect grefs
2194	*/
2195	int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2196
2197	BUG_ON(!list_empty(&rinfo->indirect_pages));
2198	for (i = 0; i < num; i++) {
2199	struct page *indirect_page = alloc_page(GFP_KERNEL |
2200	__GFP_ZERO);
2201	if (!indirect_page)
2202	goto out_of_memory;
2203	list_add(new: &indirect_page->lru, head: &rinfo->indirect_pages);
2204	}
2205	}
2206
2207	for (i = 0; i < BLK_RING_SIZE(info); i++) {
2208	rinfo->shadow[i].grants_used =
2209	kvcalloc(n: grants,
2210	size: sizeof(rinfo->shadow[i].grants_used[0]),
2211	GFP_KERNEL);
2212	rinfo->shadow[i].sg = kvcalloc(n: psegs,
2213	size: sizeof(rinfo->shadow[i].sg[0]),
2214	GFP_KERNEL);
2215	if (info->max_indirect_segments)
2216	rinfo->shadow[i].indirect_grants =
2217	kvcalloc(INDIRECT_GREFS(grants),
2218	size: sizeof(rinfo->shadow[i].indirect_grants[0]),
2219	GFP_KERNEL);
2220	if ((rinfo->shadow[i].grants_used == NULL) ||
2221	(rinfo->shadow[i].sg == NULL) ||
2222	(info->max_indirect_segments &&
2223	(rinfo->shadow[i].indirect_grants == NULL)))
2224	goto out_of_memory;
2225	sg_init_table(rinfo->shadow[i].sg, psegs);
2226	}
2227
2228	memalloc_noio_restore(flags: memflags);
2229
2230	return 0;
2231
2232	out_of_memory:
2233	for (i = 0; i < BLK_RING_SIZE(info); i++) {
2234	kvfree(addr: rinfo->shadow[i].grants_used);
2235	rinfo->shadow[i].grants_used = NULL;
2236	kvfree(addr: rinfo->shadow[i].sg);
2237	rinfo->shadow[i].sg = NULL;
2238	kvfree(addr: rinfo->shadow[i].indirect_grants);
2239	rinfo->shadow[i].indirect_grants = NULL;
2240	}
2241	if (!list_empty(head: &rinfo->indirect_pages)) {
2242	struct page *indirect_page, *n;
2243	list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2244	list_del(entry: &indirect_page->lru);
2245	__free_page(indirect_page);
2246	}
2247	}
2248
2249	memalloc_noio_restore(flags: memflags);
2250
2251	return -ENOMEM;
2252	}
2253
2254	/*
2255	* Gather all backend feature-*
2256	*/
2257	static void blkfront_gather_backend_features(struct blkfront_info *info)
2258	{
2259	unsigned int indirect_segments;
2260
2261	info->feature_flush = 0;
2262	info->feature_fua = 0;
2263
2264	/*
2265	* If there's no "feature-barrier" defined, then it means
2266	* we're dealing with a very old backend which writes
2267	* synchronously; nothing to do.
2268	*
2269	* If there are barriers, then we use flush.
2270	*/
2271	if (xenbus_read_unsigned(dir: info->xbdev->otherend, node: "feature-barrier", default_val: 0)) {
2272	info->feature_flush = 1;
2273	info->feature_fua = 1;
2274	}
2275
2276	/*
2277	* And if there is "feature-flush-cache" use that above
2278	* barriers.
2279	*/
2280	if (xenbus_read_unsigned(dir: info->xbdev->otherend, node: "feature-flush-cache",
2281	default_val: 0)) {
2282	info->feature_flush = 1;
2283	info->feature_fua = 0;
2284	}
2285
2286	if (xenbus_read_unsigned(dir: info->xbdev->otherend, node: "feature-discard", default_val: 0))
2287	blkfront_setup_discard(info);
2288
2289	if (info->feature_persistent_parm)
2290	info->feature_persistent =
2291	!!xenbus_read_unsigned(dir: info->xbdev->otherend,
2292	node: "feature-persistent", default_val: 0);
2293	if (info->feature_persistent)
2294	info->bounce = true;
2295
2296	indirect_segments = xenbus_read_unsigned(dir: info->xbdev->otherend,
2297	node: "feature-max-indirect-segments", default_val: 0);
2298	if (indirect_segments > xen_blkif_max_segments)
2299	indirect_segments = xen_blkif_max_segments;
2300	if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2301	indirect_segments = 0;
2302	info->max_indirect_segments = indirect_segments;
2303
2304	if (info->feature_persistent) {
2305	mutex_lock(&blkfront_mutex);
2306	schedule_delayed_work(dwork: &blkfront_work, HZ * 10);
2307	mutex_unlock(lock: &blkfront_mutex);
2308	}
2309	}
2310
2311	/*
2312	* Invoked when the backend is finally 'ready' (and has told produced
2313	* the details about the physical device - #sectors, size, etc).
2314	*/
2315	static void blkfront_connect(struct blkfront_info *info)
2316	{
2317	unsigned long long sectors;
2318	unsigned long sector_size;
2319	unsigned int physical_sector_size;
2320	int err, i;
2321	struct blkfront_ring_info *rinfo;
2322
2323	switch (info->connected) {
2324	case BLKIF_STATE_CONNECTED:
2325	/*
2326	* Potentially, the back-end may be signalling
2327	* a capacity change; update the capacity.
2328	*/
2329	err = xenbus_scanf(XBT_NIL, dir: info->xbdev->otherend,
2330	node: "sectors", fmt: "%Lu", &sectors);
2331	if (XENBUS_EXIST_ERR(err))
2332	return;
2333	printk(KERN_INFO "Setting capacity to %Lu\n",
2334	sectors);
2335	set_capacity_and_notify(info->gd, sectors);
2336
2337	return;
2338	case BLKIF_STATE_SUSPENDED:
2339	/*
2340	* If we are recovering from suspension, we need to wait
2341	* for the backend to announce it's features before
2342	* reconnecting, at least we need to know if the backend
2343	* supports indirect descriptors, and how many.
2344	*/
2345	blkif_recover(info);
2346	return;
2347
2348	default:
2349	break;
2350	}
2351
2352	dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2353	__func__, info->xbdev->otherend);
2354
2355	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2356	"sectors", "%llu", &sectors,
2357	"info", "%u", &info->vdisk_info,
2358	"sector-size", "%lu", &sector_size,
2359	NULL);
2360	if (err) {
2361	xenbus_dev_fatal(info->xbdev, err,
2362	"reading backend fields at %s",
2363	info->xbdev->otherend);
2364	return;
2365	}
2366
2367	/*
2368	* physical-sector-size is a newer field, so old backends may not
2369	* provide this. Assume physical sector size to be the same as
2370	* sector_size in that case.
2371	*/
2372	physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2373	"physical-sector-size",
2374	sector_size);
2375	blkfront_gather_backend_features(info);
2376	for_each_rinfo(info, rinfo, i) {
2377	err = blkfront_setup_indirect(rinfo);
2378	if (err) {
2379	xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2380	info->xbdev->otherend);
2381	blkif_free(info, 0);
2382	break;
2383	}
2384	}
2385
2386	err = xlvbd_alloc_gendisk(sectors, info, sector_size,
2387	physical_sector_size);
2388	if (err) {
2389	xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2390	info->xbdev->otherend);
2391	goto fail;
2392	}
2393
2394	xenbus_switch_state(info->xbdev, XenbusStateConnected);
2395
2396	/* Kick pending requests. */
2397	info->connected = BLKIF_STATE_CONNECTED;
2398	for_each_rinfo(info, rinfo, i)
2399	kick_pending_request_queues(rinfo);
2400
2401	err = device_add_disk(&info->xbdev->dev, info->gd, NULL);
2402	if (err) {
2403	put_disk(info->gd);
2404	blk_mq_free_tag_set(&info->tag_set);
2405	info->rq = NULL;
2406	goto fail;
2407	}
2408
2409	info->is_ready = 1;
2410	return;
2411
2412	fail:
2413	blkif_free(info, 0);
2414	return;
2415	}
2416
2417	/*
2418	* Callback received when the backend's state changes.
2419	*/
2420	static void blkback_changed(struct xenbus_device *dev,
2421	enum xenbus_state backend_state)
2422	{
2423	struct blkfront_info *info = dev_get_drvdata(dev: &dev->dev);
2424
2425	dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2426
2427	switch (backend_state) {
2428	case XenbusStateInitWait:
2429	if (dev->state != XenbusStateInitialising)
2430	break;
2431	if (talk_to_blkback(dev, info))
2432	break;
2433	break;
2434	case XenbusStateInitialising:
2435	case XenbusStateInitialised:
2436	case XenbusStateReconfiguring:
2437	case XenbusStateReconfigured:
2438	case XenbusStateUnknown:
2439	break;
2440
2441	case XenbusStateConnected:
2442	/*
2443	* talk_to_blkback sets state to XenbusStateInitialised
2444	* and blkfront_connect sets it to XenbusStateConnected
2445	* (if connection went OK).
2446	*
2447	* If the backend (or toolstack) decides to poke at backend
2448	* state (and re-trigger the watch by setting the state repeatedly
2449	* to XenbusStateConnected (4)) we need to deal with this.
2450	* This is allowed as this is used to communicate to the guest
2451	* that the size of disk has changed!
2452	*/
2453	if ((dev->state != XenbusStateInitialised) &&
2454	(dev->state != XenbusStateConnected)) {
2455	if (talk_to_blkback(dev, info))
2456	break;
2457	}
2458
2459	blkfront_connect(info);
2460	break;
2461
2462	case XenbusStateClosed:
2463	if (dev->state == XenbusStateClosed)
2464	break;
2465	fallthrough;
2466	case XenbusStateClosing:
2467	blkfront_closing(info);
2468	break;
2469	}
2470	}
2471
2472	static void blkfront_remove(struct xenbus_device *xbdev)
2473	{
2474	struct blkfront_info *info = dev_get_drvdata(dev: &xbdev->dev);
2475
2476	dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2477
2478	if (info->gd)
2479	del_gendisk(gp: info->gd);
2480
2481	mutex_lock(&blkfront_mutex);
2482	list_del(entry: &info->info_list);
2483	mutex_unlock(lock: &blkfront_mutex);
2484
2485	blkif_free(info, suspend: 0);
2486	if (info->gd) {
2487	xlbd_release_minors(minor: info->gd->first_minor, nr: info->gd->minors);
2488	put_disk(disk: info->gd);
2489	blk_mq_free_tag_set(set: &info->tag_set);
2490	}
2491
2492	kfree(objp: info);
2493	}
2494
2495	static int blkfront_is_ready(struct xenbus_device *dev)
2496	{
2497	struct blkfront_info *info = dev_get_drvdata(dev: &dev->dev);
2498
2499	return info->is_ready && info->xbdev;
2500	}
2501
2502	static const struct block_device_operations xlvbd_block_fops =
2503	{
2504	.owner = THIS_MODULE,
2505	.getgeo = blkif_getgeo,
2506	.ioctl = blkif_ioctl,
2507	.compat_ioctl = blkdev_compat_ptr_ioctl,
2508	};
2509
2510
2511	static const struct xenbus_device_id blkfront_ids[] = {
2512	{ "vbd" },
2513	{ "" }
2514	};
2515
2516	static struct xenbus_driver blkfront_driver = {
2517	.ids = blkfront_ids,
2518	.probe = blkfront_probe,
2519	.remove = blkfront_remove,
2520	.resume = blkfront_resume,
2521	.otherend_changed = blkback_changed,
2522	.is_ready = blkfront_is_ready,
2523	};
2524
2525	static void purge_persistent_grants(struct blkfront_info *info)
2526	{
2527	unsigned int i;
2528	unsigned long flags;
2529	struct blkfront_ring_info *rinfo;
2530
2531	for_each_rinfo(info, rinfo, i) {
2532	struct grant *gnt_list_entry, *tmp;
2533	LIST_HEAD(grants);
2534
2535	spin_lock_irqsave(&rinfo->ring_lock, flags);
2536
2537	if (rinfo->persistent_gnts_c == 0) {
2538	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
2539	continue;
2540	}
2541
2542	list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2543	node) {
2544	if (gnt_list_entry->gref == INVALID_GRANT_REF ||
2545	!gnttab_try_end_foreign_access(ref: gnt_list_entry->gref))
2546	continue;
2547
2548	list_del(entry: &gnt_list_entry->node);
2549	rinfo->persistent_gnts_c--;
2550	gnt_list_entry->gref = INVALID_GRANT_REF;
2551	list_add_tail(new: &gnt_list_entry->node, head: &grants);
2552	}
2553
2554	list_splice_tail(list: &grants, head: &rinfo->grants);
2555
2556	spin_unlock_irqrestore(lock: &rinfo->ring_lock, flags);
2557	}
2558	}
2559
2560	static void blkfront_delay_work(struct work_struct *work)
2561	{
2562	struct blkfront_info *info;
2563	bool need_schedule_work = false;
2564
2565	/*
2566	* Note that when using bounce buffers but not persistent grants
2567	* there's no need to run blkfront_delay_work because grants are
2568	* revoked in blkif_completion or else an error is reported and the
2569	* connection is closed.
2570	*/
2571
2572	mutex_lock(&blkfront_mutex);
2573
2574	list_for_each_entry(info, &info_list, info_list) {
2575	if (info->feature_persistent) {
2576	need_schedule_work = true;
2577	mutex_lock(&info->mutex);
2578	purge_persistent_grants(info);
2579	mutex_unlock(lock: &info->mutex);
2580	}
2581	}
2582
2583	if (need_schedule_work)
2584	schedule_delayed_work(dwork: &blkfront_work, HZ * 10);
2585
2586	mutex_unlock(lock: &blkfront_mutex);
2587	}
2588
2589	static int __init xlblk_init(void)
2590	{
2591	int ret;
2592	int nr_cpus = num_online_cpus();
2593
2594	if (!xen_domain())
2595	return -ENODEV;
2596
2597	if (!xen_has_pv_disk_devices())
2598	return -ENODEV;
2599
2600	if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2601	pr_warn("xen_blk: can't get major %d with name %s\n",
2602	XENVBD_MAJOR, DEV_NAME);
2603	return -ENODEV;
2604	}
2605
2606	if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2607	xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2608
2609	if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2610	pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2611	xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2612	xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2613	}
2614
2615	if (xen_blkif_max_queues > nr_cpus) {
2616	pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2617	xen_blkif_max_queues, nr_cpus);
2618	xen_blkif_max_queues = nr_cpus;
2619	}
2620
2621	INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2622
2623	ret = xenbus_register_frontend(&blkfront_driver);
2624	if (ret) {
2625	unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2626	return ret;
2627	}
2628
2629	return 0;
2630	}
2631	module_init(xlblk_init);
2632
2633
2634	static void __exit xlblk_exit(void)
2635	{
2636	cancel_delayed_work_sync(dwork: &blkfront_work);
2637
2638	xenbus_unregister_driver(drv: &blkfront_driver);
2639	unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2640	kfree(objp: minors);
2641	}
2642	module_exit(xlblk_exit);
2643
2644	MODULE_DESCRIPTION("Xen virtual block device frontend");
2645	MODULE_LICENSE("GPL");
2646	MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2647	MODULE_ALIAS("xen:vbd");
2648	MODULE_ALIAS("xenblk");
2649