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 #define BLK_RING_SIZE(info) \
156 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
159 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
160 * characters are enough. Define to 20 to keep consistent with backend.
162 #define RINGREF_NAME_LEN (20)
164 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
166 #define QUEUE_NAME_LEN (17)
170 * Every blkfront device can associate with one or more blkfront_ring_info,
171 * depending on how many hardware queues/rings to be used.
173 struct blkfront_ring_info {
174 /* Lock to protect data in every ring buffer. */
175 spinlock_t ring_lock;
176 struct blkif_front_ring ring;
177 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
178 unsigned int evtchn, irq;
179 struct work_struct work;
180 struct gnttab_free_callback callback;
181 struct list_head indirect_pages;
182 struct list_head grants;
183 unsigned int persistent_gnts_c;
184 unsigned long shadow_free;
185 struct blkfront_info *dev_info;
186 struct blk_shadow shadow[];
190 * We have one of these per vbd, whether ide, scsi or 'other'. They
191 * hang in private_data off the gendisk structure. We may end up
192 * putting all kinds of interesting stuff here :-)
197 struct xenbus_device *xbdev;
200 unsigned int physical_sector_size;
201 unsigned long vdisk_info;
204 enum blkif_state connected;
205 /* Number of pages per ring buffer. */
206 unsigned int nr_ring_pages;
207 struct request_queue *rq;
208 unsigned int feature_flush:1;
209 unsigned int feature_fua:1;
210 unsigned int feature_discard:1;
211 unsigned int feature_secdiscard:1;
212 unsigned int feature_persistent:1;
213 unsigned int discard_granularity;
214 unsigned int discard_alignment;
215 /* Number of 4KB segments handled */
216 unsigned int max_indirect_segments;
218 struct blk_mq_tag_set tag_set;
219 struct blkfront_ring_info *rinfo;
220 unsigned int nr_rings;
221 unsigned int rinfo_size;
222 /* Save uncomplete reqs and bios for migration. */
223 struct list_head requests;
224 struct bio_list bio_list;
225 struct list_head info_list;
228 static unsigned int nr_minors;
229 static unsigned long *minors;
230 static DEFINE_SPINLOCK(minor_lock);
232 #define PARTS_PER_DISK 16
233 #define PARTS_PER_EXT_DISK 256
235 #define BLKIF_MAJOR(dev) ((dev)>>8)
236 #define BLKIF_MINOR(dev) ((dev) & 0xff)
239 #define EXTENDED (1<<EXT_SHIFT)
240 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
241 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
242 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
243 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
244 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
245 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
247 #define DEV_NAME "xvd" /* name in /dev */
250 * Grants are always the same size as a Xen page (i.e 4KB).
251 * A physical segment is always the same size as a Linux page.
252 * Number of grants per physical segment
254 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
256 #define GRANTS_PER_INDIRECT_FRAME \
257 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
259 #define INDIRECT_GREFS(_grants) \
260 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
262 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
263 static void blkfront_gather_backend_features(struct blkfront_info *info);
264 static int negotiate_mq(struct blkfront_info *info);
266 #define for_each_rinfo(info, ptr, idx) \
267 for ((ptr) = (info)->rinfo, (idx) = 0; \
268 (idx) < (info)->nr_rings; \
269 (idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size)
271 static inline struct blkfront_ring_info *
272 get_rinfo(const struct blkfront_info *info, unsigned int i)
274 BUG_ON(i >= info->nr_rings);
275 return (void *)info->rinfo + i * info->rinfo_size;
278 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
280 unsigned long free = rinfo->shadow_free;
282 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
283 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
284 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
288 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
291 if (rinfo->shadow[id].req.u.rw.id != id)
293 if (rinfo->shadow[id].request == NULL)
295 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
296 rinfo->shadow[id].request = NULL;
297 rinfo->shadow_free = id;
301 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
303 struct blkfront_info *info = rinfo->dev_info;
304 struct page *granted_page;
305 struct grant *gnt_list_entry, *n;
309 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
313 if (info->feature_persistent) {
314 granted_page = alloc_page(GFP_NOIO);
316 kfree(gnt_list_entry);
319 gnt_list_entry->page = granted_page;
322 gnt_list_entry->gref = INVALID_GRANT_REF;
323 list_add(&gnt_list_entry->node, &rinfo->grants);
330 list_for_each_entry_safe(gnt_list_entry, n,
331 &rinfo->grants, node) {
332 list_del(&gnt_list_entry->node);
333 if (info->feature_persistent)
334 __free_page(gnt_list_entry->page);
335 kfree(gnt_list_entry);
342 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
344 struct grant *gnt_list_entry;
346 BUG_ON(list_empty(&rinfo->grants));
347 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
349 list_del(&gnt_list_entry->node);
351 if (gnt_list_entry->gref != INVALID_GRANT_REF)
352 rinfo->persistent_gnts_c--;
354 return gnt_list_entry;
357 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
358 const struct blkfront_info *info)
360 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
361 info->xbdev->otherend_id,
362 gnt_list_entry->page,
366 static struct grant *get_grant(grant_ref_t *gref_head,
368 struct blkfront_ring_info *rinfo)
370 struct grant *gnt_list_entry = get_free_grant(rinfo);
371 struct blkfront_info *info = rinfo->dev_info;
373 if (gnt_list_entry->gref != INVALID_GRANT_REF)
374 return gnt_list_entry;
376 /* Assign a gref to this page */
377 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
378 BUG_ON(gnt_list_entry->gref == -ENOSPC);
379 if (info->feature_persistent)
380 grant_foreign_access(gnt_list_entry, info);
382 /* Grant access to the GFN passed by the caller */
383 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
384 info->xbdev->otherend_id,
388 return gnt_list_entry;
391 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
392 struct blkfront_ring_info *rinfo)
394 struct grant *gnt_list_entry = get_free_grant(rinfo);
395 struct blkfront_info *info = rinfo->dev_info;
397 if (gnt_list_entry->gref != INVALID_GRANT_REF)
398 return gnt_list_entry;
400 /* Assign a gref to this page */
401 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
402 BUG_ON(gnt_list_entry->gref == -ENOSPC);
403 if (!info->feature_persistent) {
404 struct page *indirect_page;
406 /* Fetch a pre-allocated page to use for indirect grefs */
407 BUG_ON(list_empty(&rinfo->indirect_pages));
408 indirect_page = list_first_entry(&rinfo->indirect_pages,
410 list_del(&indirect_page->lru);
411 gnt_list_entry->page = indirect_page;
413 grant_foreign_access(gnt_list_entry, info);
415 return gnt_list_entry;
418 static const char *op_name(int op)
420 static const char *const names[] = {
421 [BLKIF_OP_READ] = "read",
422 [BLKIF_OP_WRITE] = "write",
423 [BLKIF_OP_WRITE_BARRIER] = "barrier",
424 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
425 [BLKIF_OP_DISCARD] = "discard" };
427 if (op < 0 || op >= ARRAY_SIZE(names))
435 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
437 unsigned int end = minor + nr;
440 if (end > nr_minors) {
441 unsigned long *bitmap, *old;
443 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
448 spin_lock(&minor_lock);
449 if (end > nr_minors) {
451 memcpy(bitmap, minors,
452 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
454 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
457 spin_unlock(&minor_lock);
461 spin_lock(&minor_lock);
462 if (find_next_bit(minors, end, minor) >= end) {
463 bitmap_set(minors, minor, nr);
467 spin_unlock(&minor_lock);
472 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
474 unsigned int end = minor + nr;
476 BUG_ON(end > nr_minors);
477 spin_lock(&minor_lock);
478 bitmap_clear(minors, minor, nr);
479 spin_unlock(&minor_lock);
482 static void blkif_restart_queue_callback(void *arg)
484 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
485 schedule_work(&rinfo->work);
488 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
490 /* We don't have real geometry info, but let's at least return
491 values consistent with the size of the device */
492 sector_t nsect = get_capacity(bd->bd_disk);
493 sector_t cylinders = nsect;
497 sector_div(cylinders, hg->heads * hg->sectors);
498 hg->cylinders = cylinders;
499 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
500 hg->cylinders = 0xffff;
504 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
505 unsigned command, unsigned long argument)
507 struct blkfront_info *info = bdev->bd_disk->private_data;
511 case CDROMMULTISESSION:
512 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
513 if (put_user(0, (char __user *)(argument + i)))
516 case CDROM_GET_CAPABILITY:
517 if (!(info->vdisk_info & VDISK_CDROM))
525 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
527 struct blkif_request **ring_req)
531 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
532 rinfo->ring.req_prod_pvt++;
534 id = get_id_from_freelist(rinfo);
535 rinfo->shadow[id].request = req;
536 rinfo->shadow[id].status = REQ_PROCESSING;
537 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
539 rinfo->shadow[id].req.u.rw.id = id;
544 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
546 struct blkfront_info *info = rinfo->dev_info;
547 struct blkif_request *ring_req, *final_ring_req;
550 /* Fill out a communications ring structure. */
551 id = blkif_ring_get_request(rinfo, req, &final_ring_req);
552 ring_req = &rinfo->shadow[id].req;
554 ring_req->operation = BLKIF_OP_DISCARD;
555 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
556 ring_req->u.discard.id = id;
557 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
558 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
559 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
561 ring_req->u.discard.flag = 0;
563 /* Copy the request to the ring page. */
564 *final_ring_req = *ring_req;
565 rinfo->shadow[id].status = REQ_WAITING;
570 struct setup_rw_req {
571 unsigned int grant_idx;
572 struct blkif_request_segment *segments;
573 struct blkfront_ring_info *rinfo;
574 struct blkif_request *ring_req;
575 grant_ref_t gref_head;
577 /* Only used when persistent grant is used and it's a write request */
579 unsigned int bvec_off;
582 bool require_extra_req;
583 struct blkif_request *extra_ring_req;
586 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
587 unsigned int len, void *data)
589 struct setup_rw_req *setup = data;
591 struct grant *gnt_list_entry;
592 unsigned int fsect, lsect;
593 /* Convenient aliases */
594 unsigned int grant_idx = setup->grant_idx;
595 struct blkif_request *ring_req = setup->ring_req;
596 struct blkfront_ring_info *rinfo = setup->rinfo;
598 * We always use the shadow of the first request to store the list
599 * of grant associated to the block I/O request. This made the
600 * completion more easy to handle even if the block I/O request is
603 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
605 if (unlikely(setup->require_extra_req &&
606 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
608 * We are using the second request, setup grant_idx
609 * to be the index of the segment array.
611 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
612 ring_req = setup->extra_ring_req;
615 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
616 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
618 kunmap_atomic(setup->segments);
620 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
621 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
622 shadow->indirect_grants[n] = gnt_list_entry;
623 setup->segments = kmap_atomic(gnt_list_entry->page);
624 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
627 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
628 ref = gnt_list_entry->gref;
630 * All the grants are stored in the shadow of the first
631 * request. Therefore we have to use the global index.
633 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
635 if (setup->need_copy) {
638 shared_data = kmap_atomic(gnt_list_entry->page);
640 * this does not wipe data stored outside the
641 * range sg->offset..sg->offset+sg->length.
642 * Therefore, blkback *could* see data from
643 * previous requests. This is OK as long as
644 * persistent grants are shared with just one
645 * domain. It may need refactoring if this
648 memcpy(shared_data + offset,
649 setup->bvec_data + setup->bvec_off,
652 kunmap_atomic(shared_data);
653 setup->bvec_off += len;
657 lsect = fsect + (len >> 9) - 1;
658 if (ring_req->operation != BLKIF_OP_INDIRECT) {
659 ring_req->u.rw.seg[grant_idx] =
660 (struct blkif_request_segment) {
663 .last_sect = lsect };
665 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
666 (struct blkif_request_segment) {
669 .last_sect = lsect };
672 (setup->grant_idx)++;
675 static void blkif_setup_extra_req(struct blkif_request *first,
676 struct blkif_request *second)
678 uint16_t nr_segments = first->u.rw.nr_segments;
681 * The second request is only present when the first request uses
682 * all its segments. It's always the continuity of the first one.
684 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
686 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
687 second->u.rw.sector_number = first->u.rw.sector_number +
688 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
690 second->u.rw.handle = first->u.rw.handle;
691 second->operation = first->operation;
694 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
696 struct blkfront_info *info = rinfo->dev_info;
697 struct blkif_request *ring_req, *extra_ring_req = NULL;
698 struct blkif_request *final_ring_req, *final_extra_ring_req = NULL;
699 unsigned long id, extra_id = NO_ASSOCIATED_ID;
700 bool require_extra_req = false;
702 struct setup_rw_req setup = {
706 .need_copy = rq_data_dir(req) && info->feature_persistent,
710 * Used to store if we are able to queue the request by just using
711 * existing persistent grants, or if we have to get new grants,
712 * as there are not sufficiently many free.
714 bool new_persistent_gnts = false;
715 struct scatterlist *sg;
716 int num_sg, max_grefs, num_grant;
718 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
719 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
721 * If we are using indirect segments we need to account
722 * for the indirect grefs used in the request.
724 max_grefs += INDIRECT_GREFS(max_grefs);
726 /* Check if we have enough persistent grants to allocate a requests */
727 if (rinfo->persistent_gnts_c < max_grefs) {
728 new_persistent_gnts = true;
730 if (gnttab_alloc_grant_references(
731 max_grefs - rinfo->persistent_gnts_c,
732 &setup.gref_head) < 0) {
733 gnttab_request_free_callback(
735 blkif_restart_queue_callback,
737 max_grefs - rinfo->persistent_gnts_c);
742 /* Fill out a communications ring structure. */
743 id = blkif_ring_get_request(rinfo, req, &final_ring_req);
744 ring_req = &rinfo->shadow[id].req;
746 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
748 /* Calculate the number of grant used */
749 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
750 num_grant += gnttab_count_grant(sg->offset, sg->length);
752 require_extra_req = info->max_indirect_segments == 0 &&
753 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
754 BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
756 rinfo->shadow[id].num_sg = num_sg;
757 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
758 likely(!require_extra_req)) {
760 * The indirect operation can only be a BLKIF_OP_READ or
763 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
764 ring_req->operation = BLKIF_OP_INDIRECT;
765 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
766 BLKIF_OP_WRITE : BLKIF_OP_READ;
767 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
768 ring_req->u.indirect.handle = info->handle;
769 ring_req->u.indirect.nr_segments = num_grant;
771 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
772 ring_req->u.rw.handle = info->handle;
773 ring_req->operation = rq_data_dir(req) ?
774 BLKIF_OP_WRITE : BLKIF_OP_READ;
775 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
777 * Ideally we can do an unordered flush-to-disk.
778 * In case the backend onlysupports barriers, use that.
779 * A barrier request a superset of FUA, so we can
780 * implement it the same way. (It's also a FLUSH+FUA,
781 * since it is guaranteed ordered WRT previous writes.)
783 if (info->feature_flush && info->feature_fua)
784 ring_req->operation =
785 BLKIF_OP_WRITE_BARRIER;
786 else if (info->feature_flush)
787 ring_req->operation =
788 BLKIF_OP_FLUSH_DISKCACHE;
790 ring_req->operation = 0;
792 ring_req->u.rw.nr_segments = num_grant;
793 if (unlikely(require_extra_req)) {
794 extra_id = blkif_ring_get_request(rinfo, req,
795 &final_extra_ring_req);
796 extra_ring_req = &rinfo->shadow[extra_id].req;
799 * Only the first request contains the scatter-gather
802 rinfo->shadow[extra_id].num_sg = 0;
804 blkif_setup_extra_req(ring_req, extra_ring_req);
806 /* Link the 2 requests together */
807 rinfo->shadow[extra_id].associated_id = id;
808 rinfo->shadow[id].associated_id = extra_id;
812 setup.ring_req = ring_req;
815 setup.require_extra_req = require_extra_req;
816 if (unlikely(require_extra_req))
817 setup.extra_ring_req = extra_ring_req;
819 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
820 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
822 if (setup.need_copy) {
823 setup.bvec_off = sg->offset;
824 setup.bvec_data = kmap_atomic(sg_page(sg));
827 gnttab_foreach_grant_in_range(sg_page(sg),
830 blkif_setup_rw_req_grant,
834 kunmap_atomic(setup.bvec_data);
837 kunmap_atomic(setup.segments);
839 /* Copy request(s) to the ring page. */
840 *final_ring_req = *ring_req;
841 rinfo->shadow[id].status = REQ_WAITING;
842 if (unlikely(require_extra_req)) {
843 *final_extra_ring_req = *extra_ring_req;
844 rinfo->shadow[extra_id].status = REQ_WAITING;
847 if (new_persistent_gnts)
848 gnttab_free_grant_references(setup.gref_head);
854 * Generate a Xen blkfront IO request from a blk layer request. Reads
855 * and writes are handled as expected.
857 * @req: a request struct
859 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
861 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
864 if (unlikely(req_op(req) == REQ_OP_DISCARD ||
865 req_op(req) == REQ_OP_SECURE_ERASE))
866 return blkif_queue_discard_req(req, rinfo);
868 return blkif_queue_rw_req(req, rinfo);
871 static inline void flush_requests(struct blkfront_ring_info *rinfo)
875 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
878 notify_remote_via_irq(rinfo->irq);
881 static inline bool blkif_request_flush_invalid(struct request *req,
882 struct blkfront_info *info)
884 return (blk_rq_is_passthrough(req) ||
885 ((req_op(req) == REQ_OP_FLUSH) &&
886 !info->feature_flush) ||
887 ((req->cmd_flags & REQ_FUA) &&
888 !info->feature_fua));
891 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
892 const struct blk_mq_queue_data *qd)
895 int qid = hctx->queue_num;
896 struct blkfront_info *info = hctx->queue->queuedata;
897 struct blkfront_ring_info *rinfo = NULL;
899 rinfo = get_rinfo(info, qid);
900 blk_mq_start_request(qd->rq);
901 spin_lock_irqsave(&rinfo->ring_lock, flags);
902 if (RING_FULL(&rinfo->ring))
905 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
908 if (blkif_queue_request(qd->rq, rinfo))
911 flush_requests(rinfo);
912 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
916 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
917 return BLK_STS_IOERR;
920 blk_mq_stop_hw_queue(hctx);
921 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
922 return BLK_STS_DEV_RESOURCE;
925 static void blkif_complete_rq(struct request *rq)
927 blk_mq_end_request(rq, blkif_req(rq)->error);
930 static const struct blk_mq_ops blkfront_mq_ops = {
931 .queue_rq = blkif_queue_rq,
932 .complete = blkif_complete_rq,
935 static void blkif_set_queue_limits(struct blkfront_info *info)
937 struct request_queue *rq = info->rq;
938 struct gendisk *gd = info->gd;
939 unsigned int segments = info->max_indirect_segments ? :
940 BLKIF_MAX_SEGMENTS_PER_REQUEST;
942 blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
944 if (info->feature_discard) {
945 blk_queue_max_discard_sectors(rq, get_capacity(gd));
946 rq->limits.discard_granularity = info->discard_granularity ?:
947 info->physical_sector_size;
948 rq->limits.discard_alignment = info->discard_alignment;
949 if (info->feature_secdiscard)
950 blk_queue_max_secure_erase_sectors(rq,
954 /* Hard sector size and max sectors impersonate the equiv. hardware. */
955 blk_queue_logical_block_size(rq, info->sector_size);
956 blk_queue_physical_block_size(rq, info->physical_sector_size);
957 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
959 /* Each segment in a request is up to an aligned page in size. */
960 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
961 blk_queue_max_segment_size(rq, PAGE_SIZE);
963 /* Ensure a merged request will fit in a single I/O ring slot. */
964 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
966 /* Make sure buffer addresses are sector-aligned. */
967 blk_queue_dma_alignment(rq, 511);
970 static const char *flush_info(struct blkfront_info *info)
972 if (info->feature_flush && info->feature_fua)
973 return "barrier: enabled;";
974 else if (info->feature_flush)
975 return "flush diskcache: enabled;";
977 return "barrier or flush: disabled;";
980 static void xlvbd_flush(struct blkfront_info *info)
982 blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
983 info->feature_fua ? true : false);
984 pr_info("blkfront: %s: %s %s %s %s %s\n",
985 info->gd->disk_name, flush_info(info),
986 "persistent grants:", info->feature_persistent ?
987 "enabled;" : "disabled;", "indirect descriptors:",
988 info->max_indirect_segments ? "enabled;" : "disabled;");
991 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
994 major = BLKIF_MAJOR(vdevice);
995 *minor = BLKIF_MINOR(vdevice);
998 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
999 *minor = ((*minor / 64) * PARTS_PER_DISK) +
1000 EMULATED_HD_DISK_MINOR_OFFSET;
1002 case XEN_IDE1_MAJOR:
1003 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1004 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1005 EMULATED_HD_DISK_MINOR_OFFSET;
1007 case XEN_SCSI_DISK0_MAJOR:
1008 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1009 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1011 case XEN_SCSI_DISK1_MAJOR:
1012 case XEN_SCSI_DISK2_MAJOR:
1013 case XEN_SCSI_DISK3_MAJOR:
1014 case XEN_SCSI_DISK4_MAJOR:
1015 case XEN_SCSI_DISK5_MAJOR:
1016 case XEN_SCSI_DISK6_MAJOR:
1017 case XEN_SCSI_DISK7_MAJOR:
1018 *offset = (*minor / PARTS_PER_DISK) +
1019 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1020 EMULATED_SD_DISK_NAME_OFFSET;
1022 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1023 EMULATED_SD_DISK_MINOR_OFFSET;
1025 case XEN_SCSI_DISK8_MAJOR:
1026 case XEN_SCSI_DISK9_MAJOR:
1027 case XEN_SCSI_DISK10_MAJOR:
1028 case XEN_SCSI_DISK11_MAJOR:
1029 case XEN_SCSI_DISK12_MAJOR:
1030 case XEN_SCSI_DISK13_MAJOR:
1031 case XEN_SCSI_DISK14_MAJOR:
1032 case XEN_SCSI_DISK15_MAJOR:
1033 *offset = (*minor / PARTS_PER_DISK) +
1034 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1035 EMULATED_SD_DISK_NAME_OFFSET;
1037 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1038 EMULATED_SD_DISK_MINOR_OFFSET;
1041 *offset = *minor / PARTS_PER_DISK;
1044 printk(KERN_WARNING "blkfront: your disk configuration is "
1045 "incorrect, please use an xvd device instead\n");
1051 static char *encode_disk_name(char *ptr, unsigned int n)
1054 ptr = encode_disk_name(ptr, n / 26 - 1);
1055 *ptr = 'a' + n % 26;
1059 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1060 struct blkfront_info *info, u16 sector_size,
1061 unsigned int physical_sector_size)
1066 unsigned int offset;
1071 BUG_ON(info->gd != NULL);
1072 BUG_ON(info->rq != NULL);
1074 if ((info->vdevice>>EXT_SHIFT) > 1) {
1075 /* this is above the extended range; something is wrong */
1076 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1080 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1081 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1084 nr_parts = PARTS_PER_DISK;
1086 minor = BLKIF_MINOR_EXT(info->vdevice);
1087 nr_parts = PARTS_PER_EXT_DISK;
1088 offset = minor / nr_parts;
1089 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1090 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1091 "emulated IDE disks,\n\t choose an xvd device name"
1092 "from xvde on\n", info->vdevice);
1094 if (minor >> MINORBITS) {
1095 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1096 info->vdevice, minor);
1100 if ((minor % nr_parts) == 0)
1101 nr_minors = nr_parts;
1103 err = xlbd_reserve_minors(minor, nr_minors);
1107 memset(&info->tag_set, 0, sizeof(info->tag_set));
1108 info->tag_set.ops = &blkfront_mq_ops;
1109 info->tag_set.nr_hw_queues = info->nr_rings;
1110 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
1112 * When indirect descriptior is not supported, the I/O request
1113 * will be split between multiple request in the ring.
1114 * To avoid problems when sending the request, divide by
1115 * 2 the depth of the queue.
1117 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
1119 info->tag_set.queue_depth = BLK_RING_SIZE(info);
1120 info->tag_set.numa_node = NUMA_NO_NODE;
1121 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1122 info->tag_set.cmd_size = sizeof(struct blkif_req);
1123 info->tag_set.driver_data = info;
1125 err = blk_mq_alloc_tag_set(&info->tag_set);
1127 goto out_release_minors;
1129 gd = blk_mq_alloc_disk(&info->tag_set, info);
1132 goto out_free_tag_set;
1135 strcpy(gd->disk_name, DEV_NAME);
1136 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1137 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1141 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1142 "%d", minor & (nr_parts - 1));
1144 gd->major = XENVBD_MAJOR;
1145 gd->first_minor = minor;
1146 gd->minors = nr_minors;
1147 gd->fops = &xlvbd_block_fops;
1148 gd->private_data = info;
1149 set_capacity(gd, capacity);
1151 info->rq = gd->queue;
1153 info->sector_size = sector_size;
1154 info->physical_sector_size = physical_sector_size;
1155 blkif_set_queue_limits(info);
1159 if (info->vdisk_info & VDISK_READONLY)
1161 if (info->vdisk_info & VDISK_REMOVABLE)
1162 gd->flags |= GENHD_FL_REMOVABLE;
1167 blk_mq_free_tag_set(&info->tag_set);
1169 xlbd_release_minors(minor, nr_minors);
1173 /* Already hold rinfo->ring_lock. */
1174 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1176 if (!RING_FULL(&rinfo->ring))
1177 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1180 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1182 unsigned long flags;
1184 spin_lock_irqsave(&rinfo->ring_lock, flags);
1185 kick_pending_request_queues_locked(rinfo);
1186 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1189 static void blkif_restart_queue(struct work_struct *work)
1191 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1193 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1194 kick_pending_request_queues(rinfo);
1197 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1199 struct grant *persistent_gnt, *n;
1200 struct blkfront_info *info = rinfo->dev_info;
1204 * Remove indirect pages, this only happens when using indirect
1205 * descriptors but not persistent grants
1207 if (!list_empty(&rinfo->indirect_pages)) {
1208 struct page *indirect_page, *n;
1210 BUG_ON(info->feature_persistent);
1211 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1212 list_del(&indirect_page->lru);
1213 __free_page(indirect_page);
1217 /* Remove all persistent grants. */
1218 if (!list_empty(&rinfo->grants)) {
1219 list_for_each_entry_safe(persistent_gnt, n,
1220 &rinfo->grants, node) {
1221 list_del(&persistent_gnt->node);
1222 if (persistent_gnt->gref != INVALID_GRANT_REF) {
1223 gnttab_end_foreign_access(persistent_gnt->gref,
1225 rinfo->persistent_gnts_c--;
1227 if (info->feature_persistent)
1228 __free_page(persistent_gnt->page);
1229 kfree(persistent_gnt);
1232 BUG_ON(rinfo->persistent_gnts_c != 0);
1234 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1236 * Clear persistent grants present in requests already
1237 * on the shared ring
1239 if (!rinfo->shadow[i].request)
1242 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1243 rinfo->shadow[i].req.u.indirect.nr_segments :
1244 rinfo->shadow[i].req.u.rw.nr_segments;
1245 for (j = 0; j < segs; j++) {
1246 persistent_gnt = rinfo->shadow[i].grants_used[j];
1247 gnttab_end_foreign_access(persistent_gnt->gref, 0UL);
1248 if (info->feature_persistent)
1249 __free_page(persistent_gnt->page);
1250 kfree(persistent_gnt);
1253 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1255 * If this is not an indirect operation don't try to
1256 * free indirect segments
1260 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1261 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1262 gnttab_end_foreign_access(persistent_gnt->gref, 0UL);
1263 __free_page(persistent_gnt->page);
1264 kfree(persistent_gnt);
1268 kvfree(rinfo->shadow[i].grants_used);
1269 rinfo->shadow[i].grants_used = NULL;
1270 kvfree(rinfo->shadow[i].indirect_grants);
1271 rinfo->shadow[i].indirect_grants = NULL;
1272 kvfree(rinfo->shadow[i].sg);
1273 rinfo->shadow[i].sg = NULL;
1276 /* No more gnttab callback work. */
1277 gnttab_cancel_free_callback(&rinfo->callback);
1279 /* Flush gnttab callback work. Must be done with no locks held. */
1280 flush_work(&rinfo->work);
1282 /* Free resources associated with old device channel. */
1283 xenbus_teardown_ring((void **)&rinfo->ring.sring, info->nr_ring_pages,
1287 unbind_from_irqhandler(rinfo->irq, rinfo);
1288 rinfo->evtchn = rinfo->irq = 0;
1291 static void blkif_free(struct blkfront_info *info, int suspend)
1294 struct blkfront_ring_info *rinfo;
1296 /* Prevent new requests being issued until we fix things up. */
1297 info->connected = suspend ?
1298 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1299 /* No more blkif_request(). */
1301 blk_mq_stop_hw_queues(info->rq);
1303 for_each_rinfo(info, rinfo, i)
1304 blkif_free_ring(rinfo);
1306 kvfree(info->rinfo);
1311 struct copy_from_grant {
1312 const struct blk_shadow *s;
1313 unsigned int grant_idx;
1314 unsigned int bvec_offset;
1318 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1319 unsigned int len, void *data)
1321 struct copy_from_grant *info = data;
1323 /* Convenient aliases */
1324 const struct blk_shadow *s = info->s;
1326 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1328 memcpy(info->bvec_data + info->bvec_offset,
1329 shared_data + offset, len);
1331 info->bvec_offset += len;
1334 kunmap_atomic(shared_data);
1337 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1341 case BLKIF_RSP_OKAY:
1343 case BLKIF_RSP_EOPNOTSUPP:
1344 return REQ_EOPNOTSUPP;
1345 case BLKIF_RSP_ERROR:
1352 * Get the final status of the block request based on two ring response
1354 static int blkif_get_final_status(enum blk_req_status s1,
1355 enum blk_req_status s2)
1357 BUG_ON(s1 < REQ_DONE);
1358 BUG_ON(s2 < REQ_DONE);
1360 if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1361 return BLKIF_RSP_ERROR;
1362 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1363 return BLKIF_RSP_EOPNOTSUPP;
1364 return BLKIF_RSP_OKAY;
1369 * 1 response processed.
1370 * 0 missing further responses.
1371 * -1 error while processing.
1373 static int blkif_completion(unsigned long *id,
1374 struct blkfront_ring_info *rinfo,
1375 struct blkif_response *bret)
1378 struct scatterlist *sg;
1379 int num_sg, num_grant;
1380 struct blkfront_info *info = rinfo->dev_info;
1381 struct blk_shadow *s = &rinfo->shadow[*id];
1382 struct copy_from_grant data = {
1386 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1387 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1389 /* The I/O request may be split in two. */
1390 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1391 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1393 /* Keep the status of the current response in shadow. */
1394 s->status = blkif_rsp_to_req_status(bret->status);
1396 /* Wait the second response if not yet here. */
1397 if (s2->status < REQ_DONE)
1400 bret->status = blkif_get_final_status(s->status,
1404 * All the grants is stored in the first shadow in order
1405 * to make the completion code simpler.
1407 num_grant += s2->req.u.rw.nr_segments;
1410 * The two responses may not come in order. Only the
1411 * first request will store the scatter-gather list.
1413 if (s2->num_sg != 0) {
1414 /* Update "id" with the ID of the first response. */
1415 *id = s->associated_id;
1420 * We don't need anymore the second request, so recycling
1423 if (add_id_to_freelist(rinfo, s->associated_id))
1424 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1425 info->gd->disk_name, s->associated_id);
1431 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1432 for_each_sg(s->sg, sg, num_sg, i) {
1433 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1435 data.bvec_offset = sg->offset;
1436 data.bvec_data = kmap_atomic(sg_page(sg));
1438 gnttab_foreach_grant_in_range(sg_page(sg),
1441 blkif_copy_from_grant,
1444 kunmap_atomic(data.bvec_data);
1447 /* Add the persistent grant into the list of free grants */
1448 for (i = 0; i < num_grant; i++) {
1449 if (!gnttab_try_end_foreign_access(s->grants_used[i]->gref)) {
1451 * If the grant is still mapped by the backend (the
1452 * backend has chosen to make this grant persistent)
1453 * we add it at the head of the list, so it will be
1456 if (!info->feature_persistent) {
1457 pr_alert("backed has not unmapped grant: %u\n",
1458 s->grants_used[i]->gref);
1461 list_add(&s->grants_used[i]->node, &rinfo->grants);
1462 rinfo->persistent_gnts_c++;
1465 * If the grant is not mapped by the backend we add it
1466 * to the tail of the list, so it will not be picked
1467 * again unless we run out of persistent grants.
1469 s->grants_used[i]->gref = INVALID_GRANT_REF;
1470 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1473 if (s->req.operation == BLKIF_OP_INDIRECT) {
1474 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1475 if (!gnttab_try_end_foreign_access(s->indirect_grants[i]->gref)) {
1476 if (!info->feature_persistent) {
1477 pr_alert("backed has not unmapped grant: %u\n",
1478 s->indirect_grants[i]->gref);
1481 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1482 rinfo->persistent_gnts_c++;
1484 struct page *indirect_page;
1487 * Add the used indirect page back to the list of
1488 * available pages for indirect grefs.
1490 if (!info->feature_persistent) {
1491 indirect_page = s->indirect_grants[i]->page;
1492 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1494 s->indirect_grants[i]->gref = INVALID_GRANT_REF;
1495 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1503 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1505 struct request *req;
1506 struct blkif_response bret;
1508 unsigned long flags;
1509 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1510 struct blkfront_info *info = rinfo->dev_info;
1511 unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
1513 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1514 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
1518 spin_lock_irqsave(&rinfo->ring_lock, flags);
1520 rp = READ_ONCE(rinfo->ring.sring->rsp_prod);
1521 virt_rmb(); /* Ensure we see queued responses up to 'rp'. */
1522 if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) {
1523 pr_alert("%s: illegal number of responses %u\n",
1524 info->gd->disk_name, rp - rinfo->ring.rsp_cons);
1528 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1534 RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
1538 * The backend has messed up and given us an id that we would
1539 * never have given to it (we stamp it up to BLK_RING_SIZE -
1540 * look in get_id_from_freelist.
1542 if (id >= BLK_RING_SIZE(info)) {
1543 pr_alert("%s: response has incorrect id (%ld)\n",
1544 info->gd->disk_name, id);
1547 if (rinfo->shadow[id].status != REQ_WAITING) {
1548 pr_alert("%s: response references no pending request\n",
1549 info->gd->disk_name);
1553 rinfo->shadow[id].status = REQ_PROCESSING;
1554 req = rinfo->shadow[id].request;
1556 op = rinfo->shadow[id].req.operation;
1557 if (op == BLKIF_OP_INDIRECT)
1558 op = rinfo->shadow[id].req.u.indirect.indirect_op;
1559 if (bret.operation != op) {
1560 pr_alert("%s: response has wrong operation (%u instead of %u)\n",
1561 info->gd->disk_name, bret.operation, op);
1565 if (bret.operation != BLKIF_OP_DISCARD) {
1569 * We may need to wait for an extra response if the
1570 * I/O request is split in 2
1572 ret = blkif_completion(&id, rinfo, &bret);
1575 if (unlikely(ret < 0))
1579 if (add_id_to_freelist(rinfo, id)) {
1580 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1581 info->gd->disk_name, op_name(bret.operation), id);
1585 if (bret.status == BLKIF_RSP_OKAY)
1586 blkif_req(req)->error = BLK_STS_OK;
1588 blkif_req(req)->error = BLK_STS_IOERR;
1590 switch (bret.operation) {
1591 case BLKIF_OP_DISCARD:
1592 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1593 struct request_queue *rq = info->rq;
1595 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1596 info->gd->disk_name, op_name(bret.operation));
1597 blkif_req(req)->error = BLK_STS_NOTSUPP;
1598 info->feature_discard = 0;
1599 info->feature_secdiscard = 0;
1600 blk_queue_max_discard_sectors(rq, 0);
1601 blk_queue_max_secure_erase_sectors(rq, 0);
1604 case BLKIF_OP_FLUSH_DISKCACHE:
1605 case BLKIF_OP_WRITE_BARRIER:
1606 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1607 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1608 info->gd->disk_name, op_name(bret.operation));
1609 blkif_req(req)->error = BLK_STS_NOTSUPP;
1611 if (unlikely(bret.status == BLKIF_RSP_ERROR &&
1612 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1613 pr_warn_ratelimited("blkfront: %s: empty %s op failed\n",
1614 info->gd->disk_name, op_name(bret.operation));
1615 blkif_req(req)->error = BLK_STS_NOTSUPP;
1617 if (unlikely(blkif_req(req)->error)) {
1618 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1619 blkif_req(req)->error = BLK_STS_OK;
1620 info->feature_fua = 0;
1621 info->feature_flush = 0;
1626 case BLKIF_OP_WRITE:
1627 if (unlikely(bret.status != BLKIF_RSP_OKAY))
1628 dev_dbg_ratelimited(&info->xbdev->dev,
1629 "Bad return from blkdev data request: %#x\n",
1637 if (likely(!blk_should_fake_timeout(req->q)))
1638 blk_mq_complete_request(req);
1641 rinfo->ring.rsp_cons = i;
1643 if (i != rinfo->ring.req_prod_pvt) {
1645 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1649 rinfo->ring.sring->rsp_event = i + 1;
1651 kick_pending_request_queues_locked(rinfo);
1653 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1655 xen_irq_lateeoi(irq, eoiflag);
1660 info->connected = BLKIF_STATE_ERROR;
1662 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1664 /* No EOI in order to avoid further interrupts. */
1666 pr_alert("%s disabled for further use\n", info->gd->disk_name);
1671 static int setup_blkring(struct xenbus_device *dev,
1672 struct blkfront_ring_info *rinfo)
1674 struct blkif_sring *sring;
1676 struct blkfront_info *info = rinfo->dev_info;
1677 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1679 err = xenbus_setup_ring(dev, GFP_NOIO, (void **)&sring,
1680 info->nr_ring_pages, rinfo->ring_ref);
1684 XEN_FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1686 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1690 err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt,
1693 xenbus_dev_fatal(dev, err,
1694 "bind_evtchn_to_irqhandler failed");
1701 blkif_free(info, 0);
1706 * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1707 * ring buffer may have multi pages depending on ->nr_ring_pages.
1709 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1710 struct blkfront_ring_info *rinfo, const char *dir)
1714 const char *message = NULL;
1715 struct blkfront_info *info = rinfo->dev_info;
1717 if (info->nr_ring_pages == 1) {
1718 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1720 message = "writing ring-ref";
1721 goto abort_transaction;
1724 for (i = 0; i < info->nr_ring_pages; i++) {
1725 char ring_ref_name[RINGREF_NAME_LEN];
1727 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1728 err = xenbus_printf(xbt, dir, ring_ref_name,
1729 "%u", rinfo->ring_ref[i]);
1731 message = "writing ring-ref";
1732 goto abort_transaction;
1737 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1739 message = "writing event-channel";
1740 goto abort_transaction;
1746 xenbus_transaction_end(xbt, 1);
1748 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1753 /* Common code used when first setting up, and when resuming. */
1754 static int talk_to_blkback(struct xenbus_device *dev,
1755 struct blkfront_info *info)
1757 const char *message = NULL;
1758 struct xenbus_transaction xbt;
1760 unsigned int i, max_page_order;
1761 unsigned int ring_page_order;
1762 struct blkfront_ring_info *rinfo;
1767 max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1768 "max-ring-page-order", 0);
1769 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1770 info->nr_ring_pages = 1 << ring_page_order;
1772 err = negotiate_mq(info);
1774 goto destroy_blkring;
1776 for_each_rinfo(info, rinfo, i) {
1777 /* Create shared ring, alloc event channel. */
1778 err = setup_blkring(dev, rinfo);
1780 goto destroy_blkring;
1784 err = xenbus_transaction_start(&xbt);
1786 xenbus_dev_fatal(dev, err, "starting transaction");
1787 goto destroy_blkring;
1790 if (info->nr_ring_pages > 1) {
1791 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1794 message = "writing ring-page-order";
1795 goto abort_transaction;
1799 /* We already got the number of queues/rings in _probe */
1800 if (info->nr_rings == 1) {
1801 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename);
1803 goto destroy_blkring;
1808 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1811 message = "writing multi-queue-num-queues";
1812 goto abort_transaction;
1815 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1816 path = kmalloc(pathsize, GFP_KERNEL);
1819 message = "ENOMEM while writing ring references";
1820 goto abort_transaction;
1823 for_each_rinfo(info, rinfo, i) {
1824 memset(path, 0, pathsize);
1825 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1826 err = write_per_ring_nodes(xbt, rinfo, path);
1829 goto destroy_blkring;
1834 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1835 XEN_IO_PROTO_ABI_NATIVE);
1837 message = "writing protocol";
1838 goto abort_transaction;
1840 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
1841 info->feature_persistent);
1844 "writing persistent grants feature to xenbus");
1846 err = xenbus_transaction_end(xbt, 0);
1850 xenbus_dev_fatal(dev, err, "completing transaction");
1851 goto destroy_blkring;
1854 for_each_rinfo(info, rinfo, i) {
1857 for (j = 0; j < BLK_RING_SIZE(info); j++)
1858 rinfo->shadow[j].req.u.rw.id = j + 1;
1859 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1861 xenbus_switch_state(dev, XenbusStateInitialised);
1866 xenbus_transaction_end(xbt, 1);
1868 xenbus_dev_fatal(dev, err, "%s", message);
1870 blkif_free(info, 0);
1874 static int negotiate_mq(struct blkfront_info *info)
1876 unsigned int backend_max_queues;
1878 struct blkfront_ring_info *rinfo;
1880 BUG_ON(info->nr_rings);
1882 /* Check if backend supports multiple queues. */
1883 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1884 "multi-queue-max-queues", 1);
1885 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1886 /* We need at least one ring. */
1887 if (!info->nr_rings)
1890 info->rinfo_size = struct_size(info->rinfo, shadow,
1891 BLK_RING_SIZE(info));
1892 info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL);
1894 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1899 for_each_rinfo(info, rinfo, i) {
1900 INIT_LIST_HEAD(&rinfo->indirect_pages);
1901 INIT_LIST_HEAD(&rinfo->grants);
1902 rinfo->dev_info = info;
1903 INIT_WORK(&rinfo->work, blkif_restart_queue);
1904 spin_lock_init(&rinfo->ring_lock);
1909 /* Enable the persistent grants feature. */
1910 static bool feature_persistent = true;
1911 module_param(feature_persistent, bool, 0644);
1912 MODULE_PARM_DESC(feature_persistent,
1913 "Enables the persistent grants feature");
1916 * Entry point to this code when a new device is created. Allocate the basic
1917 * structures and the ring buffer for communication with the backend, and
1918 * inform the backend of the appropriate details for those. Switch to
1919 * Initialised state.
1921 static int blkfront_probe(struct xenbus_device *dev,
1922 const struct xenbus_device_id *id)
1925 struct blkfront_info *info;
1927 /* FIXME: Use dynamic device id if this is not set. */
1928 err = xenbus_scanf(XBT_NIL, dev->nodename,
1929 "virtual-device", "%i", &vdevice);
1931 /* go looking in the extended area instead */
1932 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1935 xenbus_dev_fatal(dev, err, "reading virtual-device");
1940 if (xen_hvm_domain()) {
1943 /* no unplug has been done: do not hook devices != xen vbds */
1944 if (xen_has_pv_and_legacy_disk_devices()) {
1947 if (!VDEV_IS_EXTENDED(vdevice))
1948 major = BLKIF_MAJOR(vdevice);
1950 major = XENVBD_MAJOR;
1952 if (major != XENVBD_MAJOR) {
1954 "%s: HVM does not support vbd %d as xen block device\n",
1959 /* do not create a PV cdrom device if we are an HVM guest */
1960 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1963 if (strncmp(type, "cdrom", 5) == 0) {
1969 info = kzalloc(sizeof(*info), GFP_KERNEL);
1971 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1977 mutex_init(&info->mutex);
1978 info->vdevice = vdevice;
1979 info->connected = BLKIF_STATE_DISCONNECTED;
1981 info->feature_persistent = feature_persistent;
1983 /* Front end dir is a number, which is used as the id. */
1984 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1985 dev_set_drvdata(&dev->dev, info);
1987 mutex_lock(&blkfront_mutex);
1988 list_add(&info->info_list, &info_list);
1989 mutex_unlock(&blkfront_mutex);
1994 static int blkif_recover(struct blkfront_info *info)
1996 unsigned int r_index;
1997 struct request *req, *n;
2001 struct blkfront_ring_info *rinfo;
2003 blkfront_gather_backend_features(info);
2004 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2005 blkif_set_queue_limits(info);
2006 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2007 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2009 for_each_rinfo(info, rinfo, r_index) {
2010 rc = blkfront_setup_indirect(rinfo);
2014 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2016 /* Now safe for us to use the shared ring */
2017 info->connected = BLKIF_STATE_CONNECTED;
2019 for_each_rinfo(info, rinfo, r_index) {
2020 /* Kick any other new requests queued since we resumed */
2021 kick_pending_request_queues(rinfo);
2024 list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2025 /* Requeue pending requests (flush or discard) */
2026 list_del_init(&req->queuelist);
2027 BUG_ON(req->nr_phys_segments > segs);
2028 blk_mq_requeue_request(req, false);
2030 blk_mq_start_stopped_hw_queues(info->rq, true);
2031 blk_mq_kick_requeue_list(info->rq);
2033 while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2034 /* Traverse the list of pending bios and re-queue them */
2042 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2043 * driver restart. We tear down our blkif structure and recreate it, but
2044 * leave the device-layer structures intact so that this is transparent to the
2045 * rest of the kernel.
2047 static int blkfront_resume(struct xenbus_device *dev)
2049 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2052 struct blkfront_ring_info *rinfo;
2054 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2056 bio_list_init(&info->bio_list);
2057 INIT_LIST_HEAD(&info->requests);
2058 for_each_rinfo(info, rinfo, i) {
2059 struct bio_list merge_bio;
2060 struct blk_shadow *shadow = rinfo->shadow;
2062 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2064 if (!shadow[j].request)
2068 * Get the bios in the request so we can re-queue them.
2070 if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2071 req_op(shadow[j].request) == REQ_OP_DISCARD ||
2072 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2073 shadow[j].request->cmd_flags & REQ_FUA) {
2075 * Flush operations don't contain bios, so
2076 * we need to requeue the whole request
2078 * XXX: but this doesn't make any sense for a
2079 * write with the FUA flag set..
2081 list_add(&shadow[j].request->queuelist, &info->requests);
2084 merge_bio.head = shadow[j].request->bio;
2085 merge_bio.tail = shadow[j].request->biotail;
2086 bio_list_merge(&info->bio_list, &merge_bio);
2087 shadow[j].request->bio = NULL;
2088 blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2092 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2094 err = talk_to_blkback(dev, info);
2096 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2099 * We have to wait for the backend to switch to
2100 * connected state, since we want to read which
2101 * features it supports.
2107 static void blkfront_closing(struct blkfront_info *info)
2109 struct xenbus_device *xbdev = info->xbdev;
2110 struct blkfront_ring_info *rinfo;
2113 if (xbdev->state == XenbusStateClosing)
2116 /* No more blkif_request(). */
2117 blk_mq_stop_hw_queues(info->rq);
2118 blk_mark_disk_dead(info->gd);
2119 set_capacity(info->gd, 0);
2121 for_each_rinfo(info, rinfo, i) {
2122 /* No more gnttab callback work. */
2123 gnttab_cancel_free_callback(&rinfo->callback);
2125 /* Flush gnttab callback work. Must be done with no locks held. */
2126 flush_work(&rinfo->work);
2129 xenbus_frontend_closed(xbdev);
2132 static void blkfront_setup_discard(struct blkfront_info *info)
2134 info->feature_discard = 1;
2135 info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
2136 "discard-granularity",
2138 info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
2139 "discard-alignment", 0);
2140 info->feature_secdiscard =
2141 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2145 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2147 unsigned int psegs, grants, memflags;
2149 struct blkfront_info *info = rinfo->dev_info;
2151 memflags = memalloc_noio_save();
2153 if (info->max_indirect_segments == 0) {
2155 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2158 * When an extra req is required, the maximum
2159 * grants supported is related to the size of the
2160 * Linux block segment.
2162 grants = GRANTS_PER_PSEG;
2166 grants = info->max_indirect_segments;
2167 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2169 err = fill_grant_buffer(rinfo,
2170 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2174 if (!info->feature_persistent && info->max_indirect_segments) {
2176 * We are using indirect descriptors but not persistent
2177 * grants, we need to allocate a set of pages that can be
2178 * used for mapping indirect grefs
2180 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2182 BUG_ON(!list_empty(&rinfo->indirect_pages));
2183 for (i = 0; i < num; i++) {
2184 struct page *indirect_page = alloc_page(GFP_KERNEL);
2187 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2191 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2192 rinfo->shadow[i].grants_used =
2194 sizeof(rinfo->shadow[i].grants_used[0]),
2196 rinfo->shadow[i].sg = kvcalloc(psegs,
2197 sizeof(rinfo->shadow[i].sg[0]),
2199 if (info->max_indirect_segments)
2200 rinfo->shadow[i].indirect_grants =
2201 kvcalloc(INDIRECT_GREFS(grants),
2202 sizeof(rinfo->shadow[i].indirect_grants[0]),
2204 if ((rinfo->shadow[i].grants_used == NULL) ||
2205 (rinfo->shadow[i].sg == NULL) ||
2206 (info->max_indirect_segments &&
2207 (rinfo->shadow[i].indirect_grants == NULL)))
2209 sg_init_table(rinfo->shadow[i].sg, psegs);
2212 memalloc_noio_restore(memflags);
2217 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2218 kvfree(rinfo->shadow[i].grants_used);
2219 rinfo->shadow[i].grants_used = NULL;
2220 kvfree(rinfo->shadow[i].sg);
2221 rinfo->shadow[i].sg = NULL;
2222 kvfree(rinfo->shadow[i].indirect_grants);
2223 rinfo->shadow[i].indirect_grants = NULL;
2225 if (!list_empty(&rinfo->indirect_pages)) {
2226 struct page *indirect_page, *n;
2227 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2228 list_del(&indirect_page->lru);
2229 __free_page(indirect_page);
2233 memalloc_noio_restore(memflags);
2239 * Gather all backend feature-*
2241 static void blkfront_gather_backend_features(struct blkfront_info *info)
2243 unsigned int indirect_segments;
2245 info->feature_flush = 0;
2246 info->feature_fua = 0;
2249 * If there's no "feature-barrier" defined, then it means
2250 * we're dealing with a very old backend which writes
2251 * synchronously; nothing to do.
2253 * If there are barriers, then we use flush.
2255 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2256 info->feature_flush = 1;
2257 info->feature_fua = 1;
2261 * And if there is "feature-flush-cache" use that above
2264 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2266 info->feature_flush = 1;
2267 info->feature_fua = 0;
2270 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2271 blkfront_setup_discard(info);
2273 if (info->feature_persistent)
2274 info->feature_persistent =
2275 !!xenbus_read_unsigned(info->xbdev->otherend,
2276 "feature-persistent", 0);
2278 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2279 "feature-max-indirect-segments", 0);
2280 if (indirect_segments > xen_blkif_max_segments)
2281 indirect_segments = xen_blkif_max_segments;
2282 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2283 indirect_segments = 0;
2284 info->max_indirect_segments = indirect_segments;
2286 if (info->feature_persistent) {
2287 mutex_lock(&blkfront_mutex);
2288 schedule_delayed_work(&blkfront_work, HZ * 10);
2289 mutex_unlock(&blkfront_mutex);
2294 * Invoked when the backend is finally 'ready' (and has told produced
2295 * the details about the physical device - #sectors, size, etc).
2297 static void blkfront_connect(struct blkfront_info *info)
2299 unsigned long long sectors;
2300 unsigned long sector_size;
2301 unsigned int physical_sector_size;
2303 struct blkfront_ring_info *rinfo;
2305 switch (info->connected) {
2306 case BLKIF_STATE_CONNECTED:
2308 * Potentially, the back-end may be signalling
2309 * a capacity change; update the capacity.
2311 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2312 "sectors", "%Lu", §ors);
2313 if (XENBUS_EXIST_ERR(err))
2315 printk(KERN_INFO "Setting capacity to %Lu\n",
2317 set_capacity_and_notify(info->gd, sectors);
2320 case BLKIF_STATE_SUSPENDED:
2322 * If we are recovering from suspension, we need to wait
2323 * for the backend to announce it's features before
2324 * reconnecting, at least we need to know if the backend
2325 * supports indirect descriptors, and how many.
2327 blkif_recover(info);
2334 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2335 __func__, info->xbdev->otherend);
2337 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2338 "sectors", "%llu", §ors,
2339 "info", "%u", &info->vdisk_info,
2340 "sector-size", "%lu", §or_size,
2343 xenbus_dev_fatal(info->xbdev, err,
2344 "reading backend fields at %s",
2345 info->xbdev->otherend);
2350 * physical-sector-size is a newer field, so old backends may not
2351 * provide this. Assume physical sector size to be the same as
2352 * sector_size in that case.
2354 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2355 "physical-sector-size",
2357 blkfront_gather_backend_features(info);
2358 for_each_rinfo(info, rinfo, i) {
2359 err = blkfront_setup_indirect(rinfo);
2361 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2362 info->xbdev->otherend);
2363 blkif_free(info, 0);
2368 err = xlvbd_alloc_gendisk(sectors, info, sector_size,
2369 physical_sector_size);
2371 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2372 info->xbdev->otherend);
2376 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2378 /* Kick pending requests. */
2379 info->connected = BLKIF_STATE_CONNECTED;
2380 for_each_rinfo(info, rinfo, i)
2381 kick_pending_request_queues(rinfo);
2383 err = device_add_disk(&info->xbdev->dev, info->gd, NULL);
2385 blk_cleanup_disk(info->gd);
2386 blk_mq_free_tag_set(&info->tag_set);
2395 blkif_free(info, 0);
2400 * Callback received when the backend's state changes.
2402 static void blkback_changed(struct xenbus_device *dev,
2403 enum xenbus_state backend_state)
2405 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2407 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2409 switch (backend_state) {
2410 case XenbusStateInitWait:
2411 if (dev->state != XenbusStateInitialising)
2413 if (talk_to_blkback(dev, info))
2416 case XenbusStateInitialising:
2417 case XenbusStateInitialised:
2418 case XenbusStateReconfiguring:
2419 case XenbusStateReconfigured:
2420 case XenbusStateUnknown:
2423 case XenbusStateConnected:
2425 * talk_to_blkback sets state to XenbusStateInitialised
2426 * and blkfront_connect sets it to XenbusStateConnected
2427 * (if connection went OK).
2429 * If the backend (or toolstack) decides to poke at backend
2430 * state (and re-trigger the watch by setting the state repeatedly
2431 * to XenbusStateConnected (4)) we need to deal with this.
2432 * This is allowed as this is used to communicate to the guest
2433 * that the size of disk has changed!
2435 if ((dev->state != XenbusStateInitialised) &&
2436 (dev->state != XenbusStateConnected)) {
2437 if (talk_to_blkback(dev, info))
2441 blkfront_connect(info);
2444 case XenbusStateClosed:
2445 if (dev->state == XenbusStateClosed)
2448 case XenbusStateClosing:
2449 blkfront_closing(info);
2454 static int blkfront_remove(struct xenbus_device *xbdev)
2456 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2458 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2460 del_gendisk(info->gd);
2462 mutex_lock(&blkfront_mutex);
2463 list_del(&info->info_list);
2464 mutex_unlock(&blkfront_mutex);
2466 blkif_free(info, 0);
2467 xlbd_release_minors(info->gd->first_minor, info->gd->minors);
2468 blk_cleanup_disk(info->gd);
2469 blk_mq_free_tag_set(&info->tag_set);
2475 static int blkfront_is_ready(struct xenbus_device *dev)
2477 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2479 return info->is_ready && info->xbdev;
2482 static const struct block_device_operations xlvbd_block_fops =
2484 .owner = THIS_MODULE,
2485 .getgeo = blkif_getgeo,
2486 .ioctl = blkif_ioctl,
2487 .compat_ioctl = blkdev_compat_ptr_ioctl,
2491 static const struct xenbus_device_id blkfront_ids[] = {
2496 static struct xenbus_driver blkfront_driver = {
2497 .ids = blkfront_ids,
2498 .probe = blkfront_probe,
2499 .remove = blkfront_remove,
2500 .resume = blkfront_resume,
2501 .otherend_changed = blkback_changed,
2502 .is_ready = blkfront_is_ready,
2505 static void purge_persistent_grants(struct blkfront_info *info)
2508 unsigned long flags;
2509 struct blkfront_ring_info *rinfo;
2511 for_each_rinfo(info, rinfo, i) {
2512 struct grant *gnt_list_entry, *tmp;
2515 spin_lock_irqsave(&rinfo->ring_lock, flags);
2517 if (rinfo->persistent_gnts_c == 0) {
2518 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2522 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2524 if (gnt_list_entry->gref == INVALID_GRANT_REF ||
2525 !gnttab_try_end_foreign_access(gnt_list_entry->gref))
2528 list_del(&gnt_list_entry->node);
2529 rinfo->persistent_gnts_c--;
2530 gnt_list_entry->gref = INVALID_GRANT_REF;
2531 list_add_tail(&gnt_list_entry->node, &grants);
2534 list_splice_tail(&grants, &rinfo->grants);
2536 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2540 static void blkfront_delay_work(struct work_struct *work)
2542 struct blkfront_info *info;
2543 bool need_schedule_work = false;
2545 mutex_lock(&blkfront_mutex);
2547 list_for_each_entry(info, &info_list, info_list) {
2548 if (info->feature_persistent) {
2549 need_schedule_work = true;
2550 mutex_lock(&info->mutex);
2551 purge_persistent_grants(info);
2552 mutex_unlock(&info->mutex);
2556 if (need_schedule_work)
2557 schedule_delayed_work(&blkfront_work, HZ * 10);
2559 mutex_unlock(&blkfront_mutex);
2562 static int __init xlblk_init(void)
2565 int nr_cpus = num_online_cpus();
2570 if (!xen_has_pv_disk_devices())
2573 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2574 pr_warn("xen_blk: can't get major %d with name %s\n",
2575 XENVBD_MAJOR, DEV_NAME);
2579 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2580 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2582 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2583 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2584 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2585 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2588 if (xen_blkif_max_queues > nr_cpus) {
2589 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2590 xen_blkif_max_queues, nr_cpus);
2591 xen_blkif_max_queues = nr_cpus;
2594 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2596 ret = xenbus_register_frontend(&blkfront_driver);
2598 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2604 module_init(xlblk_init);
2607 static void __exit xlblk_exit(void)
2609 cancel_delayed_work_sync(&blkfront_work);
2611 xenbus_unregister_driver(&blkfront_driver);
2612 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2615 module_exit(xlblk_exit);
2617 MODULE_DESCRIPTION("Xen virtual block device frontend");
2618 MODULE_LICENSE("GPL");
2619 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2620 MODULE_ALIAS("xen:vbd");
2621 MODULE_ALIAS("xenblk");