4 * XenLinux virtual block device driver.
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
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:
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:
26 * The above copyright notice and this permission notice shall be included in
27 * all copies or substantial portions of the Software.
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
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>
54 #include <xen/xenbus.h>
55 #include <xen/grant_table.h>
56 #include <xen/events.h>
58 #include <xen/platform_pci.h>
60 #include <xen/interface/grant_table.h>
61 #include <xen/interface/io/blkif.h>
62 #include <xen/interface/io/protocols.h>
64 #include <asm/xen/hypervisor.h>
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
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) =
78 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
81 BLKIF_STATE_DISCONNECTED,
82 BLKIF_STATE_CONNECTED,
83 BLKIF_STATE_SUSPENDED,
90 struct list_head node;
102 struct blkif_request req;
103 struct request *request;
104 struct grant **grants_used;
105 struct grant **indirect_grants;
106 struct scatterlist *sg;
108 enum blk_req_status status;
110 #define NO_ASSOCIATED_ID ~0UL
112 * Id of the sibling if we ever need 2 requests when handling a
115 unsigned long associated_id;
122 static inline struct blkif_req *blkif_req(struct request *rq)
124 return blk_mq_rq_to_pdu(rq);
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);
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.
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)");
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");
148 * Maximum order of pages to be used for the shared ring between front and
149 * backend, 4KB page granularity is used.
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");
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");
159 #define BLK_RING_SIZE(info) \
160 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
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.
166 #define RINGREF_NAME_LEN (20)
168 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
170 #define QUEUE_NAME_LEN (17)
174 * Every blkfront device can associate with one or more blkfront_ring_info,
175 * depending on how many hardware queues/rings to be used.
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[];
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 :-)
201 struct xenbus_device *xbdev;
204 unsigned int physical_sector_size;
205 unsigned long vdisk_info;
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;
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;
236 static unsigned int nr_minors;
237 static unsigned long *minors;
238 static DEFINE_SPINLOCK(minor_lock);
240 #define PARTS_PER_DISK 16
241 #define PARTS_PER_EXT_DISK 256
243 #define BLKIF_MAJOR(dev) ((dev)>>8)
244 #define BLKIF_MINOR(dev) ((dev) & 0xff)
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)
255 #define DEV_NAME "xvd" /* name in /dev */
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
262 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
264 #define GRANTS_PER_INDIRECT_FRAME \
265 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
267 #define INDIRECT_GREFS(_grants) \
268 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
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);
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)
279 static inline struct blkfront_ring_info *
280 get_rinfo(const struct blkfront_info *info, unsigned int i)
282 BUG_ON(i >= info->nr_rings);
283 return (void *)info->rinfo + i * info->rinfo_size;
286 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
288 unsigned long free = rinfo->shadow_free;
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 */
296 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
299 if (rinfo->shadow[id].req.u.rw.id != id)
301 if (rinfo->shadow[id].request == NULL)
303 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
304 rinfo->shadow[id].request = NULL;
305 rinfo->shadow_free = id;
309 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
311 struct blkfront_info *info = rinfo->dev_info;
312 struct page *granted_page;
313 struct grant *gnt_list_entry, *n;
317 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
322 granted_page = alloc_page(GFP_NOIO | __GFP_ZERO);
324 kfree(gnt_list_entry);
327 gnt_list_entry->page = granted_page;
330 gnt_list_entry->gref = INVALID_GRANT_REF;
331 list_add(&gnt_list_entry->node, &rinfo->grants);
338 list_for_each_entry_safe(gnt_list_entry, n,
339 &rinfo->grants, node) {
340 list_del(&gnt_list_entry->node);
342 __free_page(gnt_list_entry->page);
343 kfree(gnt_list_entry);
350 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
352 struct grant *gnt_list_entry;
354 BUG_ON(list_empty(&rinfo->grants));
355 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
357 list_del(&gnt_list_entry->node);
359 if (gnt_list_entry->gref != INVALID_GRANT_REF)
360 rinfo->persistent_gnts_c--;
362 return gnt_list_entry;
365 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
366 const struct blkfront_info *info)
368 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
369 info->xbdev->otherend_id,
370 gnt_list_entry->page,
374 static struct grant *get_grant(grant_ref_t *gref_head,
376 struct blkfront_ring_info *rinfo)
378 struct grant *gnt_list_entry = get_free_grant(rinfo);
379 struct blkfront_info *info = rinfo->dev_info;
381 if (gnt_list_entry->gref != INVALID_GRANT_REF)
382 return gnt_list_entry;
384 /* Assign a gref to this page */
385 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
386 BUG_ON(gnt_list_entry->gref == -ENOSPC);
388 grant_foreign_access(gnt_list_entry, info);
390 /* Grant access to the GFN passed by the caller */
391 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
392 info->xbdev->otherend_id,
396 return gnt_list_entry;
399 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
400 struct blkfront_ring_info *rinfo)
402 struct grant *gnt_list_entry = get_free_grant(rinfo);
403 struct blkfront_info *info = rinfo->dev_info;
405 if (gnt_list_entry->gref != INVALID_GRANT_REF)
406 return gnt_list_entry;
408 /* Assign a gref to this page */
409 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
410 BUG_ON(gnt_list_entry->gref == -ENOSPC);
412 struct page *indirect_page;
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,
418 list_del(&indirect_page->lru);
419 gnt_list_entry->page = indirect_page;
421 grant_foreign_access(gnt_list_entry, info);
423 return gnt_list_entry;
426 static const char *op_name(int op)
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" };
435 if (op < 0 || op >= ARRAY_SIZE(names))
443 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
445 unsigned int end = minor + nr;
448 if (end > nr_minors) {
449 unsigned long *bitmap, *old;
451 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
456 spin_lock(&minor_lock);
457 if (end > nr_minors) {
459 memcpy(bitmap, minors,
460 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
462 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
465 spin_unlock(&minor_lock);
469 spin_lock(&minor_lock);
470 if (find_next_bit(minors, end, minor) >= end) {
471 bitmap_set(minors, minor, nr);
475 spin_unlock(&minor_lock);
480 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
482 unsigned int end = minor + nr;
484 BUG_ON(end > nr_minors);
485 spin_lock(&minor_lock);
486 bitmap_clear(minors, minor, nr);
487 spin_unlock(&minor_lock);
490 static void blkif_restart_queue_callback(void *arg)
492 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
493 schedule_work(&rinfo->work);
496 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
498 /* We don't have real geometry info, but let's at least return
499 values consistent with the size of the device */
500 sector_t nsect = get_capacity(bd->bd_disk);
501 sector_t cylinders = nsect;
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;
512 static int blkif_ioctl(struct block_device *bdev, blk_mode_t mode,
513 unsigned command, unsigned long argument)
515 struct blkfront_info *info = bdev->bd_disk->private_data;
519 case CDROMMULTISESSION:
520 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
521 if (put_user(0, (char __user *)(argument + i)))
524 case CDROM_GET_CAPABILITY:
525 if (!(info->vdisk_info & VDISK_CDROM))
533 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
535 struct blkif_request **ring_req)
539 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
540 rinfo->ring.req_prod_pvt++;
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;
547 rinfo->shadow[id].req.u.rw.id = id;
552 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
554 struct blkfront_info *info = rinfo->dev_info;
555 struct blkif_request *ring_req, *final_ring_req;
558 /* Fill out a communications ring structure. */
559 id = blkif_ring_get_request(rinfo, req, &final_ring_req);
560 ring_req = &rinfo->shadow[id].req;
562 ring_req->operation = BLKIF_OP_DISCARD;
563 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
564 ring_req->u.discard.id = id;
565 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
566 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
567 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
569 ring_req->u.discard.flag = 0;
571 /* Copy the request to the ring page. */
572 *final_ring_req = *ring_req;
573 rinfo->shadow[id].status = REQ_WAITING;
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;
585 /* Only used when persistent grant is used and it's a write request */
587 unsigned int bvec_off;
590 bool require_extra_req;
591 struct blkif_request *extra_ring_req;
594 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
595 unsigned int len, void *data)
597 struct setup_rw_req *setup = data;
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;
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
611 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
613 if (unlikely(setup->require_extra_req &&
614 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
616 * We are using the second request, setup grant_idx
617 * to be the index of the segment array.
619 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
620 ring_req = setup->extra_ring_req;
623 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
624 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
626 kunmap_atomic(setup->segments);
628 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
629 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
630 shadow->indirect_grants[n] = gnt_list_entry;
631 setup->segments = kmap_atomic(gnt_list_entry->page);
632 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
635 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
636 ref = gnt_list_entry->gref;
638 * All the grants are stored in the shadow of the first
639 * request. Therefore we have to use the global index.
641 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
643 if (setup->need_copy) {
646 shared_data = kmap_atomic(gnt_list_entry->page);
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
656 memcpy(shared_data + offset,
657 setup->bvec_data + setup->bvec_off,
660 kunmap_atomic(shared_data);
661 setup->bvec_off += len;
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) {
671 .last_sect = lsect };
673 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
674 (struct blkif_request_segment) {
677 .last_sect = lsect };
680 (setup->grant_idx)++;
683 static void blkif_setup_extra_req(struct blkif_request *first,
684 struct blkif_request *second)
686 uint16_t nr_segments = first->u.rw.nr_segments;
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.
692 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
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;
698 second->u.rw.handle = first->u.rw.handle;
699 second->operation = first->operation;
702 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
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;
710 struct setup_rw_req setup = {
714 .need_copy = rq_data_dir(req) && info->bounce,
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.
722 bool new_persistent_gnts = false;
723 struct scatterlist *sg;
724 int num_sg, max_grefs, num_grant;
726 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
727 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
729 * If we are using indirect segments we need to account
730 * for the indirect grefs used in the request.
732 max_grefs += INDIRECT_GREFS(max_grefs);
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;
738 if (gnttab_alloc_grant_references(
739 max_grefs - rinfo->persistent_gnts_c,
740 &setup.gref_head) < 0) {
741 gnttab_request_free_callback(
743 blkif_restart_queue_callback,
745 max_grefs - rinfo->persistent_gnts_c);
750 /* Fill out a communications ring structure. */
751 id = blkif_ring_get_request(rinfo, req, &final_ring_req);
752 ring_req = &rinfo->shadow[id].req;
754 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
756 /* Calculate the number of grant used */
757 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
758 num_grant += gnttab_count_grant(sg->offset, sg->length);
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);
764 rinfo->shadow[id].num_sg = num_sg;
765 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
766 likely(!require_extra_req)) {
768 * The indirect operation can only be a BLKIF_OP_READ or
771 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
772 ring_req->operation = BLKIF_OP_INDIRECT;
773 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
774 BLKIF_OP_WRITE : BLKIF_OP_READ;
775 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
776 ring_req->u.indirect.handle = info->handle;
777 ring_req->u.indirect.nr_segments = num_grant;
779 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
780 ring_req->u.rw.handle = info->handle;
781 ring_req->operation = rq_data_dir(req) ?
782 BLKIF_OP_WRITE : BLKIF_OP_READ;
783 if (req_op(req) == REQ_OP_FLUSH ||
784 (req_op(req) == REQ_OP_WRITE && (req->cmd_flags & REQ_FUA))) {
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.)
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;
799 ring_req->operation = 0;
801 ring_req->u.rw.nr_segments = num_grant;
802 if (unlikely(require_extra_req)) {
803 extra_id = blkif_ring_get_request(rinfo, req,
804 &final_extra_ring_req);
805 extra_ring_req = &rinfo->shadow[extra_id].req;
808 * Only the first request contains the scatter-gather
811 rinfo->shadow[extra_id].num_sg = 0;
813 blkif_setup_extra_req(ring_req, extra_ring_req);
815 /* Link the 2 requests together */
816 rinfo->shadow[extra_id].associated_id = id;
817 rinfo->shadow[id].associated_id = extra_id;
821 setup.ring_req = ring_req;
824 setup.require_extra_req = require_extra_req;
825 if (unlikely(require_extra_req))
826 setup.extra_ring_req = extra_ring_req;
828 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
829 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
831 if (setup.need_copy) {
832 setup.bvec_off = sg->offset;
833 setup.bvec_data = kmap_atomic(sg_page(sg));
836 gnttab_foreach_grant_in_range(sg_page(sg),
839 blkif_setup_rw_req_grant,
843 kunmap_atomic(setup.bvec_data);
846 kunmap_atomic(setup.segments);
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;
856 if (new_persistent_gnts)
857 gnttab_free_grant_references(setup.gref_head);
863 * Generate a Xen blkfront IO request from a blk layer request. Reads
864 * and writes are handled as expected.
866 * @req: a request struct
868 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
870 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
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);
877 return blkif_queue_rw_req(req, rinfo);
880 static inline void flush_requests(struct blkfront_ring_info *rinfo)
884 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
887 notify_remote_via_irq(rinfo->irq);
890 static inline bool blkif_request_flush_invalid(struct request *req,
891 struct blkfront_info *info)
893 return (blk_rq_is_passthrough(req) ||
894 ((req_op(req) == REQ_OP_FLUSH) &&
895 !info->feature_flush) ||
896 ((req->cmd_flags & REQ_FUA) &&
897 !info->feature_fua));
900 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
901 const struct blk_mq_queue_data *qd)
904 int qid = hctx->queue_num;
905 struct blkfront_info *info = hctx->queue->queuedata;
906 struct blkfront_ring_info *rinfo = NULL;
908 rinfo = get_rinfo(info, qid);
909 blk_mq_start_request(qd->rq);
910 spin_lock_irqsave(&rinfo->ring_lock, flags);
911 if (RING_FULL(&rinfo->ring))
914 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
917 if (blkif_queue_request(qd->rq, rinfo))
920 flush_requests(rinfo);
921 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
925 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
926 return BLK_STS_IOERR;
929 blk_mq_stop_hw_queue(hctx);
930 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
931 return BLK_STS_DEV_RESOURCE;
934 static void blkif_complete_rq(struct request *rq)
936 blk_mq_end_request(rq, blkif_req(rq)->error);
939 static const struct blk_mq_ops blkfront_mq_ops = {
940 .queue_rq = blkif_queue_rq,
941 .complete = blkif_complete_rq,
944 static void blkif_set_queue_limits(const struct blkfront_info *info,
945 struct queue_limits *lim)
947 unsigned int segments = info->max_indirect_segments ? :
948 BLKIF_MAX_SEGMENTS_PER_REQUEST;
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;
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;
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;
968 /* Ensure a merged request will fit in a single I/O ring slot. */
969 lim->max_segments = segments / GRANTS_PER_PSEG;
971 /* Make sure buffer addresses are sector-aligned. */
972 lim->dma_alignment = 511;
975 static const char *flush_info(struct blkfront_info *info)
977 if (info->feature_flush && info->feature_fua)
978 return "barrier: enabled;";
979 else if (info->feature_flush)
980 return "flush diskcache: enabled;";
982 return "barrier or flush: disabled;";
985 static void xlvbd_flush(struct blkfront_info *info)
987 blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
988 info->feature_fua ? true : false);
989 pr_info("blkfront: %s: %s %s %s %s %s %s %s\n",
990 info->gd->disk_name, flush_info(info),
991 "persistent grants:", info->feature_persistent ?
992 "enabled;" : "disabled;", "indirect descriptors:",
993 info->max_indirect_segments ? "enabled;" : "disabled;",
994 "bounce buffer:", info->bounce ? "enabled" : "disabled;");
997 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1000 major = BLKIF_MAJOR(vdevice);
1001 *minor = BLKIF_MINOR(vdevice);
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;
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;
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;
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;
1028 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1029 EMULATED_SD_DISK_MINOR_OFFSET;
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;
1043 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1044 EMULATED_SD_DISK_MINOR_OFFSET;
1047 *offset = *minor / PARTS_PER_DISK;
1050 printk(KERN_WARNING "blkfront: your disk configuration is "
1051 "incorrect, please use an xvd device instead\n");
1057 static char *encode_disk_name(char *ptr, unsigned int n)
1060 ptr = encode_disk_name(ptr, n / 26 - 1);
1061 *ptr = 'a' + n % 26;
1065 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1066 struct blkfront_info *info, u16 sector_size,
1067 unsigned int physical_sector_size)
1069 struct queue_limits lim = {};
1073 unsigned int offset;
1078 BUG_ON(info->gd != NULL);
1079 BUG_ON(info->rq != NULL);
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);
1087 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1088 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1091 nr_parts = PARTS_PER_DISK;
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);
1101 if (minor >> MINORBITS) {
1102 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1103 info->vdevice, minor);
1107 if ((minor % nr_parts) == 0)
1108 nr_minors = nr_parts;
1110 err = xlbd_reserve_minors(minor, nr_minors);
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) {
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.
1124 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
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;
1132 err = blk_mq_alloc_tag_set(&info->tag_set);
1134 goto out_release_minors;
1136 blkif_set_queue_limits(info, &lim);
1137 gd = blk_mq_alloc_disk(&info->tag_set, &lim, info);
1140 goto out_free_tag_set;
1142 blk_queue_flag_set(QUEUE_FLAG_VIRT, gd->queue);
1144 strcpy(gd->disk_name, DEV_NAME);
1145 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1146 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1150 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1151 "%d", minor & (nr_parts - 1));
1153 gd->major = XENVBD_MAJOR;
1154 gd->first_minor = minor;
1155 gd->minors = nr_minors;
1156 gd->fops = &xlvbd_block_fops;
1157 gd->private_data = info;
1158 set_capacity(gd, capacity);
1160 info->rq = gd->queue;
1162 info->sector_size = sector_size;
1163 info->physical_sector_size = physical_sector_size;
1167 if (info->vdisk_info & VDISK_READONLY)
1169 if (info->vdisk_info & VDISK_REMOVABLE)
1170 gd->flags |= GENHD_FL_REMOVABLE;
1175 blk_mq_free_tag_set(&info->tag_set);
1177 xlbd_release_minors(minor, nr_minors);
1181 /* Already hold rinfo->ring_lock. */
1182 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1184 if (!RING_FULL(&rinfo->ring))
1185 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1188 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1190 unsigned long flags;
1192 spin_lock_irqsave(&rinfo->ring_lock, flags);
1193 kick_pending_request_queues_locked(rinfo);
1194 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1197 static void blkif_restart_queue(struct work_struct *work)
1199 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1201 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1202 kick_pending_request_queues(rinfo);
1205 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1207 struct grant *persistent_gnt, *n;
1208 struct blkfront_info *info = rinfo->dev_info;
1212 * Remove indirect pages, this only happens when using indirect
1213 * descriptors but not persistent grants
1215 if (!list_empty(&rinfo->indirect_pages)) {
1216 struct page *indirect_page, *n;
1218 BUG_ON(info->bounce);
1219 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1220 list_del(&indirect_page->lru);
1221 __free_page(indirect_page);
1225 /* Remove all persistent grants. */
1226 if (!list_empty(&rinfo->grants)) {
1227 list_for_each_entry_safe(persistent_gnt, n,
1228 &rinfo->grants, node) {
1229 list_del(&persistent_gnt->node);
1230 if (persistent_gnt->gref != INVALID_GRANT_REF) {
1231 gnttab_end_foreign_access(persistent_gnt->gref,
1233 rinfo->persistent_gnts_c--;
1236 __free_page(persistent_gnt->page);
1237 kfree(persistent_gnt);
1240 BUG_ON(rinfo->persistent_gnts_c != 0);
1242 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1244 * Clear persistent grants present in requests already
1245 * on the shared ring
1247 if (!rinfo->shadow[i].request)
1250 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1251 rinfo->shadow[i].req.u.indirect.nr_segments :
1252 rinfo->shadow[i].req.u.rw.nr_segments;
1253 for (j = 0; j < segs; j++) {
1254 persistent_gnt = rinfo->shadow[i].grants_used[j];
1255 gnttab_end_foreign_access(persistent_gnt->gref, NULL);
1257 __free_page(persistent_gnt->page);
1258 kfree(persistent_gnt);
1261 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1263 * If this is not an indirect operation don't try to
1264 * free indirect segments
1268 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1269 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1270 gnttab_end_foreign_access(persistent_gnt->gref, NULL);
1271 __free_page(persistent_gnt->page);
1272 kfree(persistent_gnt);
1276 kvfree(rinfo->shadow[i].grants_used);
1277 rinfo->shadow[i].grants_used = NULL;
1278 kvfree(rinfo->shadow[i].indirect_grants);
1279 rinfo->shadow[i].indirect_grants = NULL;
1280 kvfree(rinfo->shadow[i].sg);
1281 rinfo->shadow[i].sg = NULL;
1284 /* No more gnttab callback work. */
1285 gnttab_cancel_free_callback(&rinfo->callback);
1287 /* Flush gnttab callback work. Must be done with no locks held. */
1288 flush_work(&rinfo->work);
1290 /* Free resources associated with old device channel. */
1291 xenbus_teardown_ring((void **)&rinfo->ring.sring, info->nr_ring_pages,
1295 unbind_from_irqhandler(rinfo->irq, rinfo);
1296 rinfo->evtchn = rinfo->irq = 0;
1299 static void blkif_free(struct blkfront_info *info, int suspend)
1302 struct blkfront_ring_info *rinfo;
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(). */
1309 blk_mq_stop_hw_queues(info->rq);
1311 for_each_rinfo(info, rinfo, i)
1312 blkif_free_ring(rinfo);
1314 kvfree(info->rinfo);
1319 struct copy_from_grant {
1320 const struct blk_shadow *s;
1321 unsigned int grant_idx;
1322 unsigned int bvec_offset;
1326 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1327 unsigned int len, void *data)
1329 struct copy_from_grant *info = data;
1331 /* Convenient aliases */
1332 const struct blk_shadow *s = info->s;
1334 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1336 memcpy(info->bvec_data + info->bvec_offset,
1337 shared_data + offset, len);
1339 info->bvec_offset += len;
1342 kunmap_atomic(shared_data);
1345 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1349 case BLKIF_RSP_OKAY:
1351 case BLKIF_RSP_EOPNOTSUPP:
1352 return REQ_EOPNOTSUPP;
1353 case BLKIF_RSP_ERROR:
1360 * Get the final status of the block request based on two ring response
1362 static int blkif_get_final_status(enum blk_req_status s1,
1363 enum blk_req_status s2)
1365 BUG_ON(s1 < REQ_DONE);
1366 BUG_ON(s2 < REQ_DONE);
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;
1377 * 1 response processed.
1378 * 0 missing further responses.
1379 * -1 error while processing.
1381 static int blkif_completion(unsigned long *id,
1382 struct blkfront_ring_info *rinfo,
1383 struct blkif_response *bret)
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 = {
1394 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1395 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
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];
1401 /* Keep the status of the current response in shadow. */
1402 s->status = blkif_rsp_to_req_status(bret->status);
1404 /* Wait the second response if not yet here. */
1405 if (s2->status < REQ_DONE)
1408 bret->status = blkif_get_final_status(s->status,
1412 * All the grants is stored in the first shadow in order
1413 * to make the completion code simpler.
1415 num_grant += s2->req.u.rw.nr_segments;
1418 * The two responses may not come in order. Only the
1419 * first request will store the scatter-gather list.
1421 if (s2->num_sg != 0) {
1422 /* Update "id" with the ID of the first response. */
1423 *id = s->associated_id;
1428 * We don't need anymore the second request, so recycling
1431 if (add_id_to_freelist(rinfo, s->associated_id))
1432 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1433 info->gd->disk_name, s->associated_id);
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);
1443 data.bvec_offset = sg->offset;
1444 data.bvec_data = kmap_atomic(sg_page(sg));
1446 gnttab_foreach_grant_in_range(sg_page(sg),
1449 blkif_copy_from_grant,
1452 kunmap_atomic(data.bvec_data);
1455 /* Add the persistent grant into the list of free grants */
1456 for (i = 0; i < num_grant; i++) {
1457 if (!gnttab_try_end_foreign_access(s->grants_used[i]->gref)) {
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
1464 if (!info->feature_persistent) {
1465 pr_alert("backed has not unmapped grant: %u\n",
1466 s->grants_used[i]->gref);
1469 list_add(&s->grants_used[i]->node, &rinfo->grants);
1470 rinfo->persistent_gnts_c++;
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.
1477 s->grants_used[i]->gref = INVALID_GRANT_REF;
1478 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1481 if (s->req.operation == BLKIF_OP_INDIRECT) {
1482 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1483 if (!gnttab_try_end_foreign_access(s->indirect_grants[i]->gref)) {
1484 if (!info->feature_persistent) {
1485 pr_alert("backed has not unmapped grant: %u\n",
1486 s->indirect_grants[i]->gref);
1489 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1490 rinfo->persistent_gnts_c++;
1492 struct page *indirect_page;
1495 * Add the used indirect page back to the list of
1496 * available pages for indirect grefs.
1498 if (!info->bounce) {
1499 indirect_page = s->indirect_grants[i]->page;
1500 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1502 s->indirect_grants[i]->gref = INVALID_GRANT_REF;
1503 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1511 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1513 struct request *req;
1514 struct blkif_response bret;
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;
1521 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1522 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
1526 spin_lock_irqsave(&rinfo->ring_lock, flags);
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);
1536 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1542 RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
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.
1550 if (id >= BLK_RING_SIZE(info)) {
1551 pr_alert("%s: response has incorrect id (%ld)\n",
1552 info->gd->disk_name, id);
1555 if (rinfo->shadow[id].status != REQ_WAITING) {
1556 pr_alert("%s: response references no pending request\n",
1557 info->gd->disk_name);
1561 rinfo->shadow[id].status = REQ_PROCESSING;
1562 req = rinfo->shadow[id].request;
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);
1573 if (bret.operation != BLKIF_OP_DISCARD) {
1577 * We may need to wait for an extra response if the
1578 * I/O request is split in 2
1580 ret = blkif_completion(&id, rinfo, &bret);
1583 if (unlikely(ret < 0))
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);
1593 if (bret.status == BLKIF_RSP_OKAY)
1594 blkif_req(req)->error = BLK_STS_OK;
1596 blkif_req(req)->error = BLK_STS_IOERR;
1598 switch (bret.operation) {
1599 case BLKIF_OP_DISCARD:
1600 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1601 struct request_queue *rq = info->rq;
1603 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1604 info->gd->disk_name, op_name(bret.operation));
1605 blkif_req(req)->error = BLK_STS_NOTSUPP;
1606 info->feature_discard = 0;
1607 info->feature_secdiscard = 0;
1608 blk_queue_max_discard_sectors(rq, 0);
1609 blk_queue_max_secure_erase_sectors(rq, 0);
1612 case BLKIF_OP_FLUSH_DISKCACHE:
1613 case BLKIF_OP_WRITE_BARRIER:
1614 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1615 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1616 info->gd->disk_name, op_name(bret.operation));
1617 blkif_req(req)->error = BLK_STS_NOTSUPP;
1619 if (unlikely(bret.status == BLKIF_RSP_ERROR &&
1620 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1621 pr_warn_ratelimited("blkfront: %s: empty %s op failed\n",
1622 info->gd->disk_name, op_name(bret.operation));
1623 blkif_req(req)->error = BLK_STS_NOTSUPP;
1625 if (unlikely(blkif_req(req)->error)) {
1626 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1627 blkif_req(req)->error = BLK_STS_OK;
1628 info->feature_fua = 0;
1629 info->feature_flush = 0;
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",
1645 if (likely(!blk_should_fake_timeout(req->q)))
1646 blk_mq_complete_request(req);
1649 rinfo->ring.rsp_cons = i;
1651 if (i != rinfo->ring.req_prod_pvt) {
1653 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1657 rinfo->ring.sring->rsp_event = i + 1;
1659 kick_pending_request_queues_locked(rinfo);
1661 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1663 xen_irq_lateeoi(irq, eoiflag);
1668 info->connected = BLKIF_STATE_ERROR;
1670 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1672 /* No EOI in order to avoid further interrupts. */
1674 pr_alert("%s disabled for further use\n", info->gd->disk_name);
1679 static int setup_blkring(struct xenbus_device *dev,
1680 struct blkfront_ring_info *rinfo)
1682 struct blkif_sring *sring;
1684 struct blkfront_info *info = rinfo->dev_info;
1685 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1687 err = xenbus_setup_ring(dev, GFP_NOIO, (void **)&sring,
1688 info->nr_ring_pages, rinfo->ring_ref);
1692 XEN_FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1694 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1698 err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt,
1701 xenbus_dev_fatal(dev, err,
1702 "bind_evtchn_to_irqhandler failed");
1709 blkif_free(info, 0);
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.
1717 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1718 struct blkfront_ring_info *rinfo, const char *dir)
1722 const char *message = NULL;
1723 struct blkfront_info *info = rinfo->dev_info;
1725 if (info->nr_ring_pages == 1) {
1726 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1728 message = "writing ring-ref";
1729 goto abort_transaction;
1732 for (i = 0; i < info->nr_ring_pages; i++) {
1733 char ring_ref_name[RINGREF_NAME_LEN];
1735 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1736 err = xenbus_printf(xbt, dir, ring_ref_name,
1737 "%u", rinfo->ring_ref[i]);
1739 message = "writing ring-ref";
1740 goto abort_transaction;
1745 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1747 message = "writing event-channel";
1748 goto abort_transaction;
1754 xenbus_transaction_end(xbt, 1);
1756 xenbus_dev_fatal(info->xbdev, err, "%s", message);
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");
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)
1771 const char *message = NULL;
1772 struct xenbus_transaction xbt;
1774 unsigned int i, max_page_order;
1775 unsigned int ring_page_order;
1776 struct blkfront_ring_info *rinfo;
1781 /* Check if backend is trusted. */
1782 info->bounce = !xen_blkif_trusted ||
1783 !xenbus_read_unsigned(dev->nodename, "trusted", 1);
1785 max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1786 "max-ring-page-order", 0);
1787 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1788 info->nr_ring_pages = 1 << ring_page_order;
1790 err = negotiate_mq(info);
1792 goto destroy_blkring;
1794 for_each_rinfo(info, rinfo, i) {
1795 /* Create shared ring, alloc event channel. */
1796 err = setup_blkring(dev, rinfo);
1798 goto destroy_blkring;
1802 err = xenbus_transaction_start(&xbt);
1804 xenbus_dev_fatal(dev, err, "starting transaction");
1805 goto destroy_blkring;
1808 if (info->nr_ring_pages > 1) {
1809 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1812 message = "writing ring-page-order";
1813 goto abort_transaction;
1817 /* We already got the number of queues/rings in _probe */
1818 if (info->nr_rings == 1) {
1819 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename);
1821 goto destroy_blkring;
1826 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1829 message = "writing multi-queue-num-queues";
1830 goto abort_transaction;
1833 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1834 path = kmalloc(pathsize, GFP_KERNEL);
1837 message = "ENOMEM while writing ring references";
1838 goto abort_transaction;
1841 for_each_rinfo(info, rinfo, i) {
1842 memset(path, 0, pathsize);
1843 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1844 err = write_per_ring_nodes(xbt, rinfo, path);
1847 goto destroy_blkring;
1852 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1853 XEN_IO_PROTO_ABI_NATIVE);
1855 message = "writing protocol";
1856 goto abort_transaction;
1858 info->feature_persistent_parm = feature_persistent;
1859 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
1860 info->feature_persistent_parm);
1863 "writing persistent grants feature to xenbus");
1865 err = xenbus_transaction_end(xbt, 0);
1869 xenbus_dev_fatal(dev, err, "completing transaction");
1870 goto destroy_blkring;
1873 for_each_rinfo(info, rinfo, i) {
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;
1880 xenbus_switch_state(dev, XenbusStateInitialised);
1885 xenbus_transaction_end(xbt, 1);
1887 xenbus_dev_fatal(dev, err, "%s", message);
1889 blkif_free(info, 0);
1893 static int negotiate_mq(struct blkfront_info *info)
1895 unsigned int backend_max_queues;
1897 struct blkfront_ring_info *rinfo;
1899 BUG_ON(info->nr_rings);
1901 /* Check if backend supports multiple queues. */
1902 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1903 "multi-queue-max-queues", 1);
1904 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1905 /* We need at least one ring. */
1906 if (!info->nr_rings)
1909 info->rinfo_size = struct_size(info->rinfo, shadow,
1910 BLK_RING_SIZE(info));
1911 info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL);
1913 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1918 for_each_rinfo(info, rinfo, i) {
1919 INIT_LIST_HEAD(&rinfo->indirect_pages);
1920 INIT_LIST_HEAD(&rinfo->grants);
1921 rinfo->dev_info = info;
1922 INIT_WORK(&rinfo->work, blkif_restart_queue);
1923 spin_lock_init(&rinfo->ring_lock);
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.
1934 static int blkfront_probe(struct xenbus_device *dev,
1935 const struct xenbus_device_id *id)
1938 struct blkfront_info *info;
1940 /* FIXME: Use dynamic device id if this is not set. */
1941 err = xenbus_scanf(XBT_NIL, dev->nodename,
1942 "virtual-device", "%i", &vdevice);
1944 /* go looking in the extended area instead */
1945 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1948 xenbus_dev_fatal(dev, err, "reading virtual-device");
1953 if (xen_hvm_domain()) {
1956 /* no unplug has been done: do not hook devices != xen vbds */
1957 if (xen_has_pv_and_legacy_disk_devices()) {
1960 if (!VDEV_IS_EXTENDED(vdevice))
1961 major = BLKIF_MAJOR(vdevice);
1963 major = XENVBD_MAJOR;
1965 if (major != XENVBD_MAJOR) {
1967 "%s: HVM does not support vbd %d as xen block device\n",
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);
1976 if (strncmp(type, "cdrom", 5) == 0) {
1982 info = kzalloc(sizeof(*info), GFP_KERNEL);
1984 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1990 mutex_init(&info->mutex);
1991 info->vdevice = vdevice;
1992 info->connected = BLKIF_STATE_DISCONNECTED;
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);
1998 mutex_lock(&blkfront_mutex);
1999 list_add(&info->info_list, &info_list);
2000 mutex_unlock(&blkfront_mutex);
2005 static int blkif_recover(struct blkfront_info *info)
2007 struct queue_limits lim;
2008 unsigned int r_index;
2009 struct request *req, *n;
2012 struct blkfront_ring_info *rinfo;
2014 lim = queue_limits_start_update(info->rq);
2015 blkfront_gather_backend_features(info);
2016 blkif_set_queue_limits(info, &lim);
2017 rc = queue_limits_commit_update(info->rq, &lim);
2021 for_each_rinfo(info, rinfo, r_index) {
2022 rc = blkfront_setup_indirect(rinfo);
2026 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2028 /* Now safe for us to use the shared ring */
2029 info->connected = BLKIF_STATE_CONNECTED;
2031 for_each_rinfo(info, rinfo, r_index) {
2032 /* Kick any other new requests queued since we resumed */
2033 kick_pending_request_queues(rinfo);
2036 list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2037 /* Requeue pending requests (flush or discard) */
2038 list_del_init(&req->queuelist);
2039 BUG_ON(req->nr_phys_segments >
2040 (info->max_indirect_segments ? :
2041 BLKIF_MAX_SEGMENTS_PER_REQUEST));
2042 blk_mq_requeue_request(req, false);
2044 blk_mq_start_stopped_hw_queues(info->rq, true);
2045 blk_mq_kick_requeue_list(info->rq);
2047 while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2048 /* Traverse the list of pending bios and re-queue them */
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.
2061 static int blkfront_resume(struct xenbus_device *dev)
2063 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2066 struct blkfront_ring_info *rinfo;
2068 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2070 bio_list_init(&info->bio_list);
2071 INIT_LIST_HEAD(&info->requests);
2072 for_each_rinfo(info, rinfo, i) {
2073 struct bio_list merge_bio;
2074 struct blk_shadow *shadow = rinfo->shadow;
2076 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2078 if (!shadow[j].request)
2082 * Get the bios in the request so we can re-queue them.
2084 if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2085 req_op(shadow[j].request) == REQ_OP_DISCARD ||
2086 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2087 shadow[j].request->cmd_flags & REQ_FUA) {
2089 * Flush operations don't contain bios, so
2090 * we need to requeue the whole request
2092 * XXX: but this doesn't make any sense for a
2093 * write with the FUA flag set..
2095 list_add(&shadow[j].request->queuelist, &info->requests);
2098 merge_bio.head = shadow[j].request->bio;
2099 merge_bio.tail = shadow[j].request->biotail;
2100 bio_list_merge(&info->bio_list, &merge_bio);
2101 shadow[j].request->bio = NULL;
2102 blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2106 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2108 err = talk_to_blkback(dev, info);
2110 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2113 * We have to wait for the backend to switch to
2114 * connected state, since we want to read which
2115 * features it supports.
2121 static void blkfront_closing(struct blkfront_info *info)
2123 struct xenbus_device *xbdev = info->xbdev;
2124 struct blkfront_ring_info *rinfo;
2127 if (xbdev->state == XenbusStateClosing)
2130 /* No more blkif_request(). */
2131 if (info->rq && info->gd) {
2132 blk_mq_stop_hw_queues(info->rq);
2133 blk_mark_disk_dead(info->gd);
2136 for_each_rinfo(info, rinfo, i) {
2137 /* No more gnttab callback work. */
2138 gnttab_cancel_free_callback(&rinfo->callback);
2140 /* Flush gnttab callback work. Must be done with no locks held. */
2141 flush_work(&rinfo->work);
2144 xenbus_frontend_closed(xbdev);
2147 static void blkfront_setup_discard(struct blkfront_info *info)
2149 info->feature_discard = 1;
2150 info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
2151 "discard-granularity",
2153 info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
2154 "discard-alignment", 0);
2155 info->feature_secdiscard =
2156 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2160 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2162 unsigned int psegs, grants, memflags;
2164 struct blkfront_info *info = rinfo->dev_info;
2166 memflags = memalloc_noio_save();
2168 if (info->max_indirect_segments == 0) {
2170 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2173 * When an extra req is required, the maximum
2174 * grants supported is related to the size of the
2175 * Linux block segment.
2177 grants = GRANTS_PER_PSEG;
2181 grants = info->max_indirect_segments;
2182 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2184 err = fill_grant_buffer(rinfo,
2185 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2189 if (!info->bounce && info->max_indirect_segments) {
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
2195 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2197 BUG_ON(!list_empty(&rinfo->indirect_pages));
2198 for (i = 0; i < num; i++) {
2199 struct page *indirect_page = alloc_page(GFP_KERNEL |
2203 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2207 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2208 rinfo->shadow[i].grants_used =
2210 sizeof(rinfo->shadow[i].grants_used[0]),
2212 rinfo->shadow[i].sg = kvcalloc(psegs,
2213 sizeof(rinfo->shadow[i].sg[0]),
2215 if (info->max_indirect_segments)
2216 rinfo->shadow[i].indirect_grants =
2217 kvcalloc(INDIRECT_GREFS(grants),
2218 sizeof(rinfo->shadow[i].indirect_grants[0]),
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)))
2225 sg_init_table(rinfo->shadow[i].sg, psegs);
2228 memalloc_noio_restore(memflags);
2233 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2234 kvfree(rinfo->shadow[i].grants_used);
2235 rinfo->shadow[i].grants_used = NULL;
2236 kvfree(rinfo->shadow[i].sg);
2237 rinfo->shadow[i].sg = NULL;
2238 kvfree(rinfo->shadow[i].indirect_grants);
2239 rinfo->shadow[i].indirect_grants = NULL;
2241 if (!list_empty(&rinfo->indirect_pages)) {
2242 struct page *indirect_page, *n;
2243 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2244 list_del(&indirect_page->lru);
2245 __free_page(indirect_page);
2249 memalloc_noio_restore(memflags);
2255 * Gather all backend feature-*
2257 static void blkfront_gather_backend_features(struct blkfront_info *info)
2259 unsigned int indirect_segments;
2261 info->feature_flush = 0;
2262 info->feature_fua = 0;
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.
2269 * If there are barriers, then we use flush.
2271 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2272 info->feature_flush = 1;
2273 info->feature_fua = 1;
2277 * And if there is "feature-flush-cache" use that above
2280 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2282 info->feature_flush = 1;
2283 info->feature_fua = 0;
2286 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2287 blkfront_setup_discard(info);
2289 if (info->feature_persistent_parm)
2290 info->feature_persistent =
2291 !!xenbus_read_unsigned(info->xbdev->otherend,
2292 "feature-persistent", 0);
2293 if (info->feature_persistent)
2294 info->bounce = true;
2296 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2297 "feature-max-indirect-segments", 0);
2298 if (indirect_segments > xen_blkif_max_segments)
2299 indirect_segments = xen_blkif_max_segments;
2300 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2301 indirect_segments = 0;
2302 info->max_indirect_segments = indirect_segments;
2304 if (info->feature_persistent) {
2305 mutex_lock(&blkfront_mutex);
2306 schedule_delayed_work(&blkfront_work, HZ * 10);
2307 mutex_unlock(&blkfront_mutex);
2312 * Invoked when the backend is finally 'ready' (and has told produced
2313 * the details about the physical device - #sectors, size, etc).
2315 static void blkfront_connect(struct blkfront_info *info)
2317 unsigned long long sectors;
2318 unsigned long sector_size;
2319 unsigned int physical_sector_size;
2321 struct blkfront_ring_info *rinfo;
2323 switch (info->connected) {
2324 case BLKIF_STATE_CONNECTED:
2326 * Potentially, the back-end may be signalling
2327 * a capacity change; update the capacity.
2329 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2330 "sectors", "%Lu", §ors);
2331 if (XENBUS_EXIST_ERR(err))
2333 printk(KERN_INFO "Setting capacity to %Lu\n",
2335 set_capacity_and_notify(info->gd, sectors);
2338 case BLKIF_STATE_SUSPENDED:
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.
2345 blkif_recover(info);
2352 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2353 __func__, info->xbdev->otherend);
2355 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2356 "sectors", "%llu", §ors,
2357 "info", "%u", &info->vdisk_info,
2358 "sector-size", "%lu", §or_size,
2361 xenbus_dev_fatal(info->xbdev, err,
2362 "reading backend fields at %s",
2363 info->xbdev->otherend);
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.
2372 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2373 "physical-sector-size",
2375 blkfront_gather_backend_features(info);
2376 for_each_rinfo(info, rinfo, i) {
2377 err = blkfront_setup_indirect(rinfo);
2379 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2380 info->xbdev->otherend);
2381 blkif_free(info, 0);
2386 err = xlvbd_alloc_gendisk(sectors, info, sector_size,
2387 physical_sector_size);
2389 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2390 info->xbdev->otherend);
2394 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2396 /* Kick pending requests. */
2397 info->connected = BLKIF_STATE_CONNECTED;
2398 for_each_rinfo(info, rinfo, i)
2399 kick_pending_request_queues(rinfo);
2401 err = device_add_disk(&info->xbdev->dev, info->gd, NULL);
2404 blk_mq_free_tag_set(&info->tag_set);
2413 blkif_free(info, 0);
2418 * Callback received when the backend's state changes.
2420 static void blkback_changed(struct xenbus_device *dev,
2421 enum xenbus_state backend_state)
2423 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2425 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2427 switch (backend_state) {
2428 case XenbusStateInitWait:
2429 if (dev->state != XenbusStateInitialising)
2431 if (talk_to_blkback(dev, info))
2434 case XenbusStateInitialising:
2435 case XenbusStateInitialised:
2436 case XenbusStateReconfiguring:
2437 case XenbusStateReconfigured:
2438 case XenbusStateUnknown:
2441 case XenbusStateConnected:
2443 * talk_to_blkback sets state to XenbusStateInitialised
2444 * and blkfront_connect sets it to XenbusStateConnected
2445 * (if connection went OK).
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!
2453 if ((dev->state != XenbusStateInitialised) &&
2454 (dev->state != XenbusStateConnected)) {
2455 if (talk_to_blkback(dev, info))
2459 blkfront_connect(info);
2462 case XenbusStateClosed:
2463 if (dev->state == XenbusStateClosed)
2466 case XenbusStateClosing:
2467 blkfront_closing(info);
2472 static void blkfront_remove(struct xenbus_device *xbdev)
2474 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2476 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2479 del_gendisk(info->gd);
2481 mutex_lock(&blkfront_mutex);
2482 list_del(&info->info_list);
2483 mutex_unlock(&blkfront_mutex);
2485 blkif_free(info, 0);
2487 xlbd_release_minors(info->gd->first_minor, info->gd->minors);
2489 blk_mq_free_tag_set(&info->tag_set);
2495 static int blkfront_is_ready(struct xenbus_device *dev)
2497 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2499 return info->is_ready && info->xbdev;
2502 static const struct block_device_operations xlvbd_block_fops =
2504 .owner = THIS_MODULE,
2505 .getgeo = blkif_getgeo,
2506 .ioctl = blkif_ioctl,
2507 .compat_ioctl = blkdev_compat_ptr_ioctl,
2511 static const struct xenbus_device_id blkfront_ids[] = {
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,
2525 static void purge_persistent_grants(struct blkfront_info *info)
2528 unsigned long flags;
2529 struct blkfront_ring_info *rinfo;
2531 for_each_rinfo(info, rinfo, i) {
2532 struct grant *gnt_list_entry, *tmp;
2535 spin_lock_irqsave(&rinfo->ring_lock, flags);
2537 if (rinfo->persistent_gnts_c == 0) {
2538 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2542 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2544 if (gnt_list_entry->gref == INVALID_GRANT_REF ||
2545 !gnttab_try_end_foreign_access(gnt_list_entry->gref))
2548 list_del(&gnt_list_entry->node);
2549 rinfo->persistent_gnts_c--;
2550 gnt_list_entry->gref = INVALID_GRANT_REF;
2551 list_add_tail(&gnt_list_entry->node, &grants);
2554 list_splice_tail(&grants, &rinfo->grants);
2556 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2560 static void blkfront_delay_work(struct work_struct *work)
2562 struct blkfront_info *info;
2563 bool need_schedule_work = false;
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.
2572 mutex_lock(&blkfront_mutex);
2574 list_for_each_entry(info, &info_list, info_list) {
2575 if (info->feature_persistent) {
2576 need_schedule_work = true;
2577 mutex_lock(&info->mutex);
2578 purge_persistent_grants(info);
2579 mutex_unlock(&info->mutex);
2583 if (need_schedule_work)
2584 schedule_delayed_work(&blkfront_work, HZ * 10);
2586 mutex_unlock(&blkfront_mutex);
2589 static int __init xlblk_init(void)
2592 int nr_cpus = num_online_cpus();
2597 if (!xen_has_pv_disk_devices())
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);
2606 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2607 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
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;
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;
2621 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2623 ret = xenbus_register_frontend(&blkfront_driver);
2625 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2631 module_init(xlblk_init);
2634 static void __exit xlblk_exit(void)
2636 cancel_delayed_work_sync(&blkfront_work);
2638 xenbus_unregister_driver(&blkfront_driver);
2639 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2642 module_exit(xlblk_exit);
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");