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/mutex.h>
46 #include <linux/scatterlist.h>
47 #include <linux/bitmap.h>
48 #include <linux/list.h>
51 #include <xen/xenbus.h>
52 #include <xen/grant_table.h>
53 #include <xen/events.h>
55 #include <xen/platform_pci.h>
57 #include <xen/interface/grant_table.h>
58 #include <xen/interface/io/blkif.h>
59 #include <xen/interface/io/protocols.h>
61 #include <asm/xen/hypervisor.h>
64 * The minimal size of segment supported by the block framework is PAGE_SIZE.
65 * When Linux is using a different page size than Xen, it may not be possible
66 * to put all the data in a single segment.
67 * This can happen when the backend doesn't support indirect descriptor and
68 * therefore the maximum amount of data that a request can carry is
69 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
71 * Note that we only support one extra request. So the Linux page size
72 * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
75 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
78 BLKIF_STATE_DISCONNECTED,
79 BLKIF_STATE_CONNECTED,
80 BLKIF_STATE_SUSPENDED,
86 struct list_head node;
97 struct blkif_request req;
98 struct request *request;
99 struct grant **grants_used;
100 struct grant **indirect_grants;
101 struct scatterlist *sg;
103 enum blk_req_status status;
105 #define NO_ASSOCIATED_ID ~0UL
107 * Id of the sibling if we ever need 2 requests when handling a
110 unsigned long associated_id;
118 static DEFINE_MUTEX(blkfront_mutex);
119 static const struct block_device_operations xlvbd_block_fops;
122 * Maximum number of segments in indirect requests, the actual value used by
123 * the frontend driver is the minimum of this value and the value provided
124 * by the backend driver.
127 static unsigned int xen_blkif_max_segments = 32;
128 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint,
130 MODULE_PARM_DESC(max_indirect_segments,
131 "Maximum amount of segments in indirect requests (default is 32)");
133 static unsigned int xen_blkif_max_queues = 4;
134 module_param_named(max_queues, xen_blkif_max_queues, uint, S_IRUGO);
135 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
138 * Maximum order of pages to be used for the shared ring between front and
139 * backend, 4KB page granularity is used.
141 static unsigned int xen_blkif_max_ring_order;
142 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO);
143 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
145 #define BLK_RING_SIZE(info) \
146 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
148 #define BLK_MAX_RING_SIZE \
149 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
152 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
153 * characters are enough. Define to 20 to keep consistent with backend.
155 #define RINGREF_NAME_LEN (20)
157 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
159 #define QUEUE_NAME_LEN (17)
163 * Every blkfront device can associate with one or more blkfront_ring_info,
164 * depending on how many hardware queues/rings to be used.
166 struct blkfront_ring_info {
167 /* Lock to protect data in every ring buffer. */
168 spinlock_t ring_lock;
169 struct blkif_front_ring ring;
170 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
171 unsigned int evtchn, irq;
172 struct work_struct work;
173 struct gnttab_free_callback callback;
174 struct blk_shadow shadow[BLK_MAX_RING_SIZE];
175 struct list_head indirect_pages;
176 struct list_head grants;
177 unsigned int persistent_gnts_c;
178 unsigned long shadow_free;
179 struct blkfront_info *dev_info;
183 * We have one of these per vbd, whether ide, scsi or 'other'. They
184 * hang in private_data off the gendisk structure. We may end up
185 * putting all kinds of interesting stuff here :-)
190 struct xenbus_device *xbdev;
194 enum blkif_state connected;
195 /* Number of pages per ring buffer. */
196 unsigned int nr_ring_pages;
197 struct request_queue *rq;
198 unsigned int feature_flush;
199 unsigned int feature_fua;
200 unsigned int feature_discard:1;
201 unsigned int feature_secdiscard:1;
202 unsigned int discard_granularity;
203 unsigned int discard_alignment;
204 unsigned int feature_persistent:1;
205 /* Number of 4KB segments handled */
206 unsigned int max_indirect_segments;
208 struct blk_mq_tag_set tag_set;
209 struct blkfront_ring_info *rinfo;
210 unsigned int nr_rings;
211 /* Save uncomplete reqs and bios for migration. */
212 struct list_head requests;
213 struct bio_list bio_list;
216 static unsigned int nr_minors;
217 static unsigned long *minors;
218 static DEFINE_SPINLOCK(minor_lock);
220 #define GRANT_INVALID_REF 0
222 #define PARTS_PER_DISK 16
223 #define PARTS_PER_EXT_DISK 256
225 #define BLKIF_MAJOR(dev) ((dev)>>8)
226 #define BLKIF_MINOR(dev) ((dev) & 0xff)
229 #define EXTENDED (1<<EXT_SHIFT)
230 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
231 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
232 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
233 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
234 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
235 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
237 #define DEV_NAME "xvd" /* name in /dev */
240 * Grants are always the same size as a Xen page (i.e 4KB).
241 * A physical segment is always the same size as a Linux page.
242 * Number of grants per physical segment
244 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
246 #define GRANTS_PER_INDIRECT_FRAME \
247 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
249 #define PSEGS_PER_INDIRECT_FRAME \
250 (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
252 #define INDIRECT_GREFS(_grants) \
253 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
255 #define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG)
257 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
258 static void blkfront_gather_backend_features(struct blkfront_info *info);
260 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
262 unsigned long free = rinfo->shadow_free;
264 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
265 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
266 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
270 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
273 if (rinfo->shadow[id].req.u.rw.id != id)
275 if (rinfo->shadow[id].request == NULL)
277 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
278 rinfo->shadow[id].request = NULL;
279 rinfo->shadow_free = id;
283 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
285 struct blkfront_info *info = rinfo->dev_info;
286 struct page *granted_page;
287 struct grant *gnt_list_entry, *n;
291 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
295 if (info->feature_persistent) {
296 granted_page = alloc_page(GFP_NOIO);
298 kfree(gnt_list_entry);
301 gnt_list_entry->page = granted_page;
304 gnt_list_entry->gref = GRANT_INVALID_REF;
305 list_add(&gnt_list_entry->node, &rinfo->grants);
312 list_for_each_entry_safe(gnt_list_entry, n,
313 &rinfo->grants, node) {
314 list_del(&gnt_list_entry->node);
315 if (info->feature_persistent)
316 __free_page(gnt_list_entry->page);
317 kfree(gnt_list_entry);
324 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
326 struct grant *gnt_list_entry;
328 BUG_ON(list_empty(&rinfo->grants));
329 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
331 list_del(&gnt_list_entry->node);
333 if (gnt_list_entry->gref != GRANT_INVALID_REF)
334 rinfo->persistent_gnts_c--;
336 return gnt_list_entry;
339 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
340 const struct blkfront_info *info)
342 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
343 info->xbdev->otherend_id,
344 gnt_list_entry->page,
348 static struct grant *get_grant(grant_ref_t *gref_head,
350 struct blkfront_ring_info *rinfo)
352 struct grant *gnt_list_entry = get_free_grant(rinfo);
353 struct blkfront_info *info = rinfo->dev_info;
355 if (gnt_list_entry->gref != GRANT_INVALID_REF)
356 return gnt_list_entry;
358 /* Assign a gref to this page */
359 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
360 BUG_ON(gnt_list_entry->gref == -ENOSPC);
361 if (info->feature_persistent)
362 grant_foreign_access(gnt_list_entry, info);
364 /* Grant access to the GFN passed by the caller */
365 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
366 info->xbdev->otherend_id,
370 return gnt_list_entry;
373 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
374 struct blkfront_ring_info *rinfo)
376 struct grant *gnt_list_entry = get_free_grant(rinfo);
377 struct blkfront_info *info = rinfo->dev_info;
379 if (gnt_list_entry->gref != GRANT_INVALID_REF)
380 return gnt_list_entry;
382 /* Assign a gref to this page */
383 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
384 BUG_ON(gnt_list_entry->gref == -ENOSPC);
385 if (!info->feature_persistent) {
386 struct page *indirect_page;
388 /* Fetch a pre-allocated page to use for indirect grefs */
389 BUG_ON(list_empty(&rinfo->indirect_pages));
390 indirect_page = list_first_entry(&rinfo->indirect_pages,
392 list_del(&indirect_page->lru);
393 gnt_list_entry->page = indirect_page;
395 grant_foreign_access(gnt_list_entry, info);
397 return gnt_list_entry;
400 static const char *op_name(int op)
402 static const char *const names[] = {
403 [BLKIF_OP_READ] = "read",
404 [BLKIF_OP_WRITE] = "write",
405 [BLKIF_OP_WRITE_BARRIER] = "barrier",
406 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
407 [BLKIF_OP_DISCARD] = "discard" };
409 if (op < 0 || op >= ARRAY_SIZE(names))
417 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
419 unsigned int end = minor + nr;
422 if (end > nr_minors) {
423 unsigned long *bitmap, *old;
425 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
430 spin_lock(&minor_lock);
431 if (end > nr_minors) {
433 memcpy(bitmap, minors,
434 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
436 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
439 spin_unlock(&minor_lock);
443 spin_lock(&minor_lock);
444 if (find_next_bit(minors, end, minor) >= end) {
445 bitmap_set(minors, minor, nr);
449 spin_unlock(&minor_lock);
454 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
456 unsigned int end = minor + nr;
458 BUG_ON(end > nr_minors);
459 spin_lock(&minor_lock);
460 bitmap_clear(minors, minor, nr);
461 spin_unlock(&minor_lock);
464 static void blkif_restart_queue_callback(void *arg)
466 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
467 schedule_work(&rinfo->work);
470 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
472 /* We don't have real geometry info, but let's at least return
473 values consistent with the size of the device */
474 sector_t nsect = get_capacity(bd->bd_disk);
475 sector_t cylinders = nsect;
479 sector_div(cylinders, hg->heads * hg->sectors);
480 hg->cylinders = cylinders;
481 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
482 hg->cylinders = 0xffff;
486 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
487 unsigned command, unsigned long argument)
489 struct blkfront_info *info = bdev->bd_disk->private_data;
492 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
493 command, (long)argument);
496 case CDROMMULTISESSION:
497 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
498 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
499 if (put_user(0, (char __user *)(argument + i)))
503 case CDROM_GET_CAPABILITY: {
504 struct gendisk *gd = info->gd;
505 if (gd->flags & GENHD_FL_CD)
511 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
513 return -EINVAL; /* same return as native Linux */
519 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
521 struct blkif_request **ring_req)
525 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
526 rinfo->ring.req_prod_pvt++;
528 id = get_id_from_freelist(rinfo);
529 rinfo->shadow[id].request = req;
530 rinfo->shadow[id].status = REQ_WAITING;
531 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
533 (*ring_req)->u.rw.id = id;
538 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
540 struct blkfront_info *info = rinfo->dev_info;
541 struct blkif_request *ring_req;
544 /* Fill out a communications ring structure. */
545 id = blkif_ring_get_request(rinfo, req, &ring_req);
547 ring_req->operation = BLKIF_OP_DISCARD;
548 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
549 ring_req->u.discard.id = id;
550 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
551 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
552 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
554 ring_req->u.discard.flag = 0;
556 /* Keep a private copy so we can reissue requests when recovering. */
557 rinfo->shadow[id].req = *ring_req;
562 struct setup_rw_req {
563 unsigned int grant_idx;
564 struct blkif_request_segment *segments;
565 struct blkfront_ring_info *rinfo;
566 struct blkif_request *ring_req;
567 grant_ref_t gref_head;
569 /* Only used when persistent grant is used and it's a read request */
571 unsigned int bvec_off;
574 bool require_extra_req;
575 struct blkif_request *extra_ring_req;
578 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
579 unsigned int len, void *data)
581 struct setup_rw_req *setup = data;
583 struct grant *gnt_list_entry;
584 unsigned int fsect, lsect;
585 /* Convenient aliases */
586 unsigned int grant_idx = setup->grant_idx;
587 struct blkif_request *ring_req = setup->ring_req;
588 struct blkfront_ring_info *rinfo = setup->rinfo;
590 * We always use the shadow of the first request to store the list
591 * of grant associated to the block I/O request. This made the
592 * completion more easy to handle even if the block I/O request is
595 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
597 if (unlikely(setup->require_extra_req &&
598 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
600 * We are using the second request, setup grant_idx
601 * to be the index of the segment array.
603 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
604 ring_req = setup->extra_ring_req;
607 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
608 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
610 kunmap_atomic(setup->segments);
612 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
613 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
614 shadow->indirect_grants[n] = gnt_list_entry;
615 setup->segments = kmap_atomic(gnt_list_entry->page);
616 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
619 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
620 ref = gnt_list_entry->gref;
622 * All the grants are stored in the shadow of the first
623 * request. Therefore we have to use the global index.
625 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
627 if (setup->need_copy) {
630 shared_data = kmap_atomic(gnt_list_entry->page);
632 * this does not wipe data stored outside the
633 * range sg->offset..sg->offset+sg->length.
634 * Therefore, blkback *could* see data from
635 * previous requests. This is OK as long as
636 * persistent grants are shared with just one
637 * domain. It may need refactoring if this
640 memcpy(shared_data + offset,
641 setup->bvec_data + setup->bvec_off,
644 kunmap_atomic(shared_data);
645 setup->bvec_off += len;
649 lsect = fsect + (len >> 9) - 1;
650 if (ring_req->operation != BLKIF_OP_INDIRECT) {
651 ring_req->u.rw.seg[grant_idx] =
652 (struct blkif_request_segment) {
655 .last_sect = lsect };
657 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
658 (struct blkif_request_segment) {
661 .last_sect = lsect };
664 (setup->grant_idx)++;
667 static void blkif_setup_extra_req(struct blkif_request *first,
668 struct blkif_request *second)
670 uint16_t nr_segments = first->u.rw.nr_segments;
673 * The second request is only present when the first request uses
674 * all its segments. It's always the continuity of the first one.
676 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
678 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
679 second->u.rw.sector_number = first->u.rw.sector_number +
680 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
682 second->u.rw.handle = first->u.rw.handle;
683 second->operation = first->operation;
686 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
688 struct blkfront_info *info = rinfo->dev_info;
689 struct blkif_request *ring_req, *extra_ring_req = NULL;
690 unsigned long id, extra_id = NO_ASSOCIATED_ID;
691 bool require_extra_req = false;
693 struct setup_rw_req setup = {
697 .need_copy = rq_data_dir(req) && info->feature_persistent,
701 * Used to store if we are able to queue the request by just using
702 * existing persistent grants, or if we have to get new grants,
703 * as there are not sufficiently many free.
705 struct scatterlist *sg;
706 int num_sg, max_grefs, num_grant;
708 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
709 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
711 * If we are using indirect segments we need to account
712 * for the indirect grefs used in the request.
714 max_grefs += INDIRECT_GREFS(max_grefs);
717 * We have to reserve 'max_grefs' grants because persistent
718 * grants are shared by all rings.
721 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) {
722 gnttab_request_free_callback(
724 blkif_restart_queue_callback,
730 /* Fill out a communications ring structure. */
731 id = blkif_ring_get_request(rinfo, req, &ring_req);
733 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
735 /* Calculate the number of grant used */
736 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
737 num_grant += gnttab_count_grant(sg->offset, sg->length);
739 require_extra_req = info->max_indirect_segments == 0 &&
740 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
741 BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
743 rinfo->shadow[id].num_sg = num_sg;
744 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
745 likely(!require_extra_req)) {
747 * The indirect operation can only be a BLKIF_OP_READ or
750 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
751 ring_req->operation = BLKIF_OP_INDIRECT;
752 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
753 BLKIF_OP_WRITE : BLKIF_OP_READ;
754 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
755 ring_req->u.indirect.handle = info->handle;
756 ring_req->u.indirect.nr_segments = num_grant;
758 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
759 ring_req->u.rw.handle = info->handle;
760 ring_req->operation = rq_data_dir(req) ?
761 BLKIF_OP_WRITE : BLKIF_OP_READ;
762 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
764 * Ideally we can do an unordered flush-to-disk.
765 * In case the backend onlysupports barriers, use that.
766 * A barrier request a superset of FUA, so we can
767 * implement it the same way. (It's also a FLUSH+FUA,
768 * since it is guaranteed ordered WRT previous writes.)
770 if (info->feature_flush && info->feature_fua)
771 ring_req->operation =
772 BLKIF_OP_WRITE_BARRIER;
773 else if (info->feature_flush)
774 ring_req->operation =
775 BLKIF_OP_FLUSH_DISKCACHE;
777 ring_req->operation = 0;
779 ring_req->u.rw.nr_segments = num_grant;
780 if (unlikely(require_extra_req)) {
781 extra_id = blkif_ring_get_request(rinfo, req,
784 * Only the first request contains the scatter-gather
787 rinfo->shadow[extra_id].num_sg = 0;
789 blkif_setup_extra_req(ring_req, extra_ring_req);
791 /* Link the 2 requests together */
792 rinfo->shadow[extra_id].associated_id = id;
793 rinfo->shadow[id].associated_id = extra_id;
797 setup.ring_req = ring_req;
800 setup.require_extra_req = require_extra_req;
801 if (unlikely(require_extra_req))
802 setup.extra_ring_req = extra_ring_req;
804 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
805 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
807 if (setup.need_copy) {
808 setup.bvec_off = sg->offset;
809 setup.bvec_data = kmap_atomic(sg_page(sg));
812 gnttab_foreach_grant_in_range(sg_page(sg),
815 blkif_setup_rw_req_grant,
819 kunmap_atomic(setup.bvec_data);
822 kunmap_atomic(setup.segments);
824 /* Keep a private copy so we can reissue requests when recovering. */
825 rinfo->shadow[id].req = *ring_req;
826 if (unlikely(require_extra_req))
827 rinfo->shadow[extra_id].req = *extra_ring_req;
830 gnttab_free_grant_references(setup.gref_head);
836 * Generate a Xen blkfront IO request from a blk layer request. Reads
837 * and writes are handled as expected.
839 * @req: a request struct
841 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
843 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
846 if (unlikely(req_op(req) == REQ_OP_DISCARD ||
847 req->cmd_flags & REQ_SECURE))
848 return blkif_queue_discard_req(req, rinfo);
850 return blkif_queue_rw_req(req, rinfo);
853 static inline void flush_requests(struct blkfront_ring_info *rinfo)
857 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
860 notify_remote_via_irq(rinfo->irq);
863 static inline bool blkif_request_flush_invalid(struct request *req,
864 struct blkfront_info *info)
866 return ((req->cmd_type != REQ_TYPE_FS) ||
867 ((req_op(req) == REQ_OP_FLUSH) &&
868 !info->feature_flush) ||
869 ((req->cmd_flags & REQ_FUA) &&
870 !info->feature_fua));
873 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
874 const struct blk_mq_queue_data *qd)
877 int qid = hctx->queue_num;
878 struct blkfront_info *info = hctx->queue->queuedata;
879 struct blkfront_ring_info *rinfo = NULL;
881 BUG_ON(info->nr_rings <= qid);
882 rinfo = &info->rinfo[qid];
883 blk_mq_start_request(qd->rq);
884 spin_lock_irqsave(&rinfo->ring_lock, flags);
885 if (RING_FULL(&rinfo->ring))
888 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
891 if (blkif_queue_request(qd->rq, rinfo))
894 flush_requests(rinfo);
895 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
896 return BLK_MQ_RQ_QUEUE_OK;
899 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
900 return BLK_MQ_RQ_QUEUE_ERROR;
903 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
904 blk_mq_stop_hw_queue(hctx);
905 return BLK_MQ_RQ_QUEUE_BUSY;
908 static struct blk_mq_ops blkfront_mq_ops = {
909 .queue_rq = blkif_queue_rq,
910 .map_queue = blk_mq_map_queue,
913 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
914 unsigned int physical_sector_size,
915 unsigned int segments)
917 struct request_queue *rq;
918 struct blkfront_info *info = gd->private_data;
920 memset(&info->tag_set, 0, sizeof(info->tag_set));
921 info->tag_set.ops = &blkfront_mq_ops;
922 info->tag_set.nr_hw_queues = info->nr_rings;
923 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
925 * When indirect descriptior is not supported, the I/O request
926 * will be split between multiple request in the ring.
927 * To avoid problems when sending the request, divide by
928 * 2 the depth of the queue.
930 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
932 info->tag_set.queue_depth = BLK_RING_SIZE(info);
933 info->tag_set.numa_node = NUMA_NO_NODE;
934 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
935 info->tag_set.cmd_size = 0;
936 info->tag_set.driver_data = info;
938 if (blk_mq_alloc_tag_set(&info->tag_set))
940 rq = blk_mq_init_queue(&info->tag_set);
942 blk_mq_free_tag_set(&info->tag_set);
946 rq->queuedata = info;
947 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
949 if (info->feature_discard) {
950 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
951 blk_queue_max_discard_sectors(rq, get_capacity(gd));
952 rq->limits.discard_granularity = info->discard_granularity;
953 rq->limits.discard_alignment = info->discard_alignment;
954 if (info->feature_secdiscard)
955 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
958 /* Hard sector size and max sectors impersonate the equiv. hardware. */
959 blk_queue_logical_block_size(rq, sector_size);
960 blk_queue_physical_block_size(rq, physical_sector_size);
961 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
963 /* Each segment in a request is up to an aligned page in size. */
964 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
965 blk_queue_max_segment_size(rq, PAGE_SIZE);
967 /* Ensure a merged request will fit in a single I/O ring slot. */
968 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
970 /* Make sure buffer addresses are sector-aligned. */
971 blk_queue_dma_alignment(rq, 511);
973 /* Make sure we don't use bounce buffers. */
974 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
981 static const char *flush_info(struct blkfront_info *info)
983 if (info->feature_flush && info->feature_fua)
984 return "barrier: enabled;";
985 else if (info->feature_flush)
986 return "flush diskcache: enabled;";
988 return "barrier or flush: disabled;";
991 static void xlvbd_flush(struct blkfront_info *info)
993 blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
994 info->feature_fua ? true : false);
995 pr_info("blkfront: %s: %s %s %s %s %s\n",
996 info->gd->disk_name, flush_info(info),
997 "persistent grants:", info->feature_persistent ?
998 "enabled;" : "disabled;", "indirect descriptors:",
999 info->max_indirect_segments ? "enabled;" : "disabled;");
1002 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1005 major = BLKIF_MAJOR(vdevice);
1006 *minor = BLKIF_MINOR(vdevice);
1008 case XEN_IDE0_MAJOR:
1009 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1010 *minor = ((*minor / 64) * PARTS_PER_DISK) +
1011 EMULATED_HD_DISK_MINOR_OFFSET;
1013 case XEN_IDE1_MAJOR:
1014 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1015 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1016 EMULATED_HD_DISK_MINOR_OFFSET;
1018 case XEN_SCSI_DISK0_MAJOR:
1019 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1020 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1022 case XEN_SCSI_DISK1_MAJOR:
1023 case XEN_SCSI_DISK2_MAJOR:
1024 case XEN_SCSI_DISK3_MAJOR:
1025 case XEN_SCSI_DISK4_MAJOR:
1026 case XEN_SCSI_DISK5_MAJOR:
1027 case XEN_SCSI_DISK6_MAJOR:
1028 case XEN_SCSI_DISK7_MAJOR:
1029 *offset = (*minor / PARTS_PER_DISK) +
1030 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1031 EMULATED_SD_DISK_NAME_OFFSET;
1033 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1034 EMULATED_SD_DISK_MINOR_OFFSET;
1036 case XEN_SCSI_DISK8_MAJOR:
1037 case XEN_SCSI_DISK9_MAJOR:
1038 case XEN_SCSI_DISK10_MAJOR:
1039 case XEN_SCSI_DISK11_MAJOR:
1040 case XEN_SCSI_DISK12_MAJOR:
1041 case XEN_SCSI_DISK13_MAJOR:
1042 case XEN_SCSI_DISK14_MAJOR:
1043 case XEN_SCSI_DISK15_MAJOR:
1044 *offset = (*minor / PARTS_PER_DISK) +
1045 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1046 EMULATED_SD_DISK_NAME_OFFSET;
1048 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1049 EMULATED_SD_DISK_MINOR_OFFSET;
1052 *offset = *minor / PARTS_PER_DISK;
1055 printk(KERN_WARNING "blkfront: your disk configuration is "
1056 "incorrect, please use an xvd device instead\n");
1062 static char *encode_disk_name(char *ptr, unsigned int n)
1065 ptr = encode_disk_name(ptr, n / 26 - 1);
1066 *ptr = 'a' + n % 26;
1070 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1071 struct blkfront_info *info,
1072 u16 vdisk_info, u16 sector_size,
1073 unsigned int physical_sector_size)
1078 unsigned int offset;
1083 BUG_ON(info->gd != NULL);
1084 BUG_ON(info->rq != NULL);
1086 if ((info->vdevice>>EXT_SHIFT) > 1) {
1087 /* this is above the extended range; something is wrong */
1088 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1092 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1093 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1096 nr_parts = PARTS_PER_DISK;
1098 minor = BLKIF_MINOR_EXT(info->vdevice);
1099 nr_parts = PARTS_PER_EXT_DISK;
1100 offset = minor / nr_parts;
1101 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1102 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1103 "emulated IDE disks,\n\t choose an xvd device name"
1104 "from xvde on\n", info->vdevice);
1106 if (minor >> MINORBITS) {
1107 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1108 info->vdevice, minor);
1112 if ((minor % nr_parts) == 0)
1113 nr_minors = nr_parts;
1115 err = xlbd_reserve_minors(minor, nr_minors);
1120 gd = alloc_disk(nr_minors);
1124 strcpy(gd->disk_name, DEV_NAME);
1125 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1126 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1130 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1131 "%d", minor & (nr_parts - 1));
1133 gd->major = XENVBD_MAJOR;
1134 gd->first_minor = minor;
1135 gd->fops = &xlvbd_block_fops;
1136 gd->private_data = info;
1137 gd->driverfs_dev = &(info->xbdev->dev);
1138 set_capacity(gd, capacity);
1140 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
1141 info->max_indirect_segments ? :
1142 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
1147 info->rq = gd->queue;
1152 if (vdisk_info & VDISK_READONLY)
1155 if (vdisk_info & VDISK_REMOVABLE)
1156 gd->flags |= GENHD_FL_REMOVABLE;
1158 if (vdisk_info & VDISK_CDROM)
1159 gd->flags |= GENHD_FL_CD;
1164 xlbd_release_minors(minor, nr_minors);
1169 static void xlvbd_release_gendisk(struct blkfront_info *info)
1171 unsigned int minor, nr_minors, i;
1173 if (info->rq == NULL)
1176 /* No more blkif_request(). */
1177 blk_mq_stop_hw_queues(info->rq);
1179 for (i = 0; i < info->nr_rings; i++) {
1180 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1182 /* No more gnttab callback work. */
1183 gnttab_cancel_free_callback(&rinfo->callback);
1185 /* Flush gnttab callback work. Must be done with no locks held. */
1186 flush_work(&rinfo->work);
1189 del_gendisk(info->gd);
1191 minor = info->gd->first_minor;
1192 nr_minors = info->gd->minors;
1193 xlbd_release_minors(minor, nr_minors);
1195 blk_cleanup_queue(info->rq);
1196 blk_mq_free_tag_set(&info->tag_set);
1203 /* Already hold rinfo->ring_lock. */
1204 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1206 if (!RING_FULL(&rinfo->ring))
1207 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1210 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1212 unsigned long flags;
1214 spin_lock_irqsave(&rinfo->ring_lock, flags);
1215 kick_pending_request_queues_locked(rinfo);
1216 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1219 static void blkif_restart_queue(struct work_struct *work)
1221 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1223 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1224 kick_pending_request_queues(rinfo);
1227 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1229 struct grant *persistent_gnt, *n;
1230 struct blkfront_info *info = rinfo->dev_info;
1234 * Remove indirect pages, this only happens when using indirect
1235 * descriptors but not persistent grants
1237 if (!list_empty(&rinfo->indirect_pages)) {
1238 struct page *indirect_page, *n;
1240 BUG_ON(info->feature_persistent);
1241 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1242 list_del(&indirect_page->lru);
1243 __free_page(indirect_page);
1247 /* Remove all persistent grants. */
1248 if (!list_empty(&rinfo->grants)) {
1249 list_for_each_entry_safe(persistent_gnt, n,
1250 &rinfo->grants, node) {
1251 list_del(&persistent_gnt->node);
1252 if (persistent_gnt->gref != GRANT_INVALID_REF) {
1253 gnttab_end_foreign_access(persistent_gnt->gref,
1255 rinfo->persistent_gnts_c--;
1257 if (info->feature_persistent)
1258 __free_page(persistent_gnt->page);
1259 kfree(persistent_gnt);
1262 BUG_ON(rinfo->persistent_gnts_c != 0);
1264 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1266 * Clear persistent grants present in requests already
1267 * on the shared ring
1269 if (!rinfo->shadow[i].request)
1272 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1273 rinfo->shadow[i].req.u.indirect.nr_segments :
1274 rinfo->shadow[i].req.u.rw.nr_segments;
1275 for (j = 0; j < segs; j++) {
1276 persistent_gnt = rinfo->shadow[i].grants_used[j];
1277 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1278 if (info->feature_persistent)
1279 __free_page(persistent_gnt->page);
1280 kfree(persistent_gnt);
1283 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1285 * If this is not an indirect operation don't try to
1286 * free indirect segments
1290 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1291 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1292 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1293 __free_page(persistent_gnt->page);
1294 kfree(persistent_gnt);
1298 kfree(rinfo->shadow[i].grants_used);
1299 rinfo->shadow[i].grants_used = NULL;
1300 kfree(rinfo->shadow[i].indirect_grants);
1301 rinfo->shadow[i].indirect_grants = NULL;
1302 kfree(rinfo->shadow[i].sg);
1303 rinfo->shadow[i].sg = NULL;
1306 /* No more gnttab callback work. */
1307 gnttab_cancel_free_callback(&rinfo->callback);
1309 /* Flush gnttab callback work. Must be done with no locks held. */
1310 flush_work(&rinfo->work);
1312 /* Free resources associated with old device channel. */
1313 for (i = 0; i < info->nr_ring_pages; i++) {
1314 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1315 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1316 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1319 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE));
1320 rinfo->ring.sring = NULL;
1323 unbind_from_irqhandler(rinfo->irq, rinfo);
1324 rinfo->evtchn = rinfo->irq = 0;
1327 static void blkif_free(struct blkfront_info *info, int suspend)
1331 /* Prevent new requests being issued until we fix things up. */
1332 info->connected = suspend ?
1333 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1334 /* No more blkif_request(). */
1336 blk_mq_stop_hw_queues(info->rq);
1338 for (i = 0; i < info->nr_rings; i++)
1339 blkif_free_ring(&info->rinfo[i]);
1346 struct copy_from_grant {
1347 const struct blk_shadow *s;
1348 unsigned int grant_idx;
1349 unsigned int bvec_offset;
1353 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1354 unsigned int len, void *data)
1356 struct copy_from_grant *info = data;
1358 /* Convenient aliases */
1359 const struct blk_shadow *s = info->s;
1361 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1363 memcpy(info->bvec_data + info->bvec_offset,
1364 shared_data + offset, len);
1366 info->bvec_offset += len;
1369 kunmap_atomic(shared_data);
1372 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1376 case BLKIF_RSP_OKAY:
1378 case BLKIF_RSP_EOPNOTSUPP:
1379 return REQ_EOPNOTSUPP;
1380 case BLKIF_RSP_ERROR:
1388 * Get the final status of the block request based on two ring response
1390 static int blkif_get_final_status(enum blk_req_status s1,
1391 enum blk_req_status s2)
1393 BUG_ON(s1 == REQ_WAITING);
1394 BUG_ON(s2 == REQ_WAITING);
1396 if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1397 return BLKIF_RSP_ERROR;
1398 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1399 return BLKIF_RSP_EOPNOTSUPP;
1400 return BLKIF_RSP_OKAY;
1403 static bool blkif_completion(unsigned long *id,
1404 struct blkfront_ring_info *rinfo,
1405 struct blkif_response *bret)
1408 struct scatterlist *sg;
1409 int num_sg, num_grant;
1410 struct blkfront_info *info = rinfo->dev_info;
1411 struct blk_shadow *s = &rinfo->shadow[*id];
1412 struct copy_from_grant data = {
1416 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1417 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1419 /* The I/O request may be split in two. */
1420 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1421 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1423 /* Keep the status of the current response in shadow. */
1424 s->status = blkif_rsp_to_req_status(bret->status);
1426 /* Wait the second response if not yet here. */
1427 if (s2->status == REQ_WAITING)
1430 bret->status = blkif_get_final_status(s->status,
1434 * All the grants is stored in the first shadow in order
1435 * to make the completion code simpler.
1437 num_grant += s2->req.u.rw.nr_segments;
1440 * The two responses may not come in order. Only the
1441 * first request will store the scatter-gather list.
1443 if (s2->num_sg != 0) {
1444 /* Update "id" with the ID of the first response. */
1445 *id = s->associated_id;
1450 * We don't need anymore the second request, so recycling
1453 if (add_id_to_freelist(rinfo, s->associated_id))
1454 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1455 info->gd->disk_name, s->associated_id);
1461 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1462 for_each_sg(s->sg, sg, num_sg, i) {
1463 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1465 data.bvec_offset = sg->offset;
1466 data.bvec_data = kmap_atomic(sg_page(sg));
1468 gnttab_foreach_grant_in_range(sg_page(sg),
1471 blkif_copy_from_grant,
1474 kunmap_atomic(data.bvec_data);
1477 /* Add the persistent grant into the list of free grants */
1478 for (i = 0; i < num_grant; i++) {
1479 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1481 * If the grant is still mapped by the backend (the
1482 * backend has chosen to make this grant persistent)
1483 * we add it at the head of the list, so it will be
1486 if (!info->feature_persistent)
1487 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1488 s->grants_used[i]->gref);
1489 list_add(&s->grants_used[i]->node, &rinfo->grants);
1490 rinfo->persistent_gnts_c++;
1493 * If the grant is not mapped by the backend we end the
1494 * foreign access and add it to the tail of the list,
1495 * so it will not be picked again unless we run out of
1496 * persistent grants.
1498 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1499 s->grants_used[i]->gref = GRANT_INVALID_REF;
1500 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1503 if (s->req.operation == BLKIF_OP_INDIRECT) {
1504 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1505 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1506 if (!info->feature_persistent)
1507 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1508 s->indirect_grants[i]->gref);
1509 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1510 rinfo->persistent_gnts_c++;
1512 struct page *indirect_page;
1514 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1516 * Add the used indirect page back to the list of
1517 * available pages for indirect grefs.
1519 if (!info->feature_persistent) {
1520 indirect_page = s->indirect_grants[i]->page;
1521 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1523 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1524 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1532 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1534 struct request *req;
1535 struct blkif_response *bret;
1537 unsigned long flags;
1538 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1539 struct blkfront_info *info = rinfo->dev_info;
1542 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1545 spin_lock_irqsave(&rinfo->ring_lock, flags);
1547 rp = rinfo->ring.sring->rsp_prod;
1548 rmb(); /* Ensure we see queued responses up to 'rp'. */
1550 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1553 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1556 * The backend has messed up and given us an id that we would
1557 * never have given to it (we stamp it up to BLK_RING_SIZE -
1558 * look in get_id_from_freelist.
1560 if (id >= BLK_RING_SIZE(info)) {
1561 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1562 info->gd->disk_name, op_name(bret->operation), id);
1563 /* We can't safely get the 'struct request' as
1564 * the id is busted. */
1567 req = rinfo->shadow[id].request;
1569 if (bret->operation != BLKIF_OP_DISCARD) {
1571 * We may need to wait for an extra response if the
1572 * I/O request is split in 2
1574 if (!blkif_completion(&id, rinfo, bret))
1578 if (add_id_to_freelist(rinfo, id)) {
1579 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1580 info->gd->disk_name, op_name(bret->operation), id);
1584 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1585 switch (bret->operation) {
1586 case BLKIF_OP_DISCARD:
1587 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1588 struct request_queue *rq = info->rq;
1589 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1590 info->gd->disk_name, op_name(bret->operation));
1591 error = -EOPNOTSUPP;
1592 info->feature_discard = 0;
1593 info->feature_secdiscard = 0;
1594 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1595 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1597 blk_mq_complete_request(req, error);
1599 case BLKIF_OP_FLUSH_DISKCACHE:
1600 case BLKIF_OP_WRITE_BARRIER:
1601 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1602 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1603 info->gd->disk_name, op_name(bret->operation));
1604 error = -EOPNOTSUPP;
1606 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1607 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1608 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1609 info->gd->disk_name, op_name(bret->operation));
1610 error = -EOPNOTSUPP;
1612 if (unlikely(error)) {
1613 if (error == -EOPNOTSUPP)
1615 info->feature_fua = 0;
1616 info->feature_flush = 0;
1621 case BLKIF_OP_WRITE:
1622 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1623 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1624 "request: %x\n", bret->status);
1626 blk_mq_complete_request(req, error);
1633 rinfo->ring.rsp_cons = i;
1635 if (i != rinfo->ring.req_prod_pvt) {
1637 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1641 rinfo->ring.sring->rsp_event = i + 1;
1643 kick_pending_request_queues_locked(rinfo);
1645 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1651 static int setup_blkring(struct xenbus_device *dev,
1652 struct blkfront_ring_info *rinfo)
1654 struct blkif_sring *sring;
1656 struct blkfront_info *info = rinfo->dev_info;
1657 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1658 grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1660 for (i = 0; i < info->nr_ring_pages; i++)
1661 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1663 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1664 get_order(ring_size));
1666 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1669 SHARED_RING_INIT(sring);
1670 FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1672 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1674 free_pages((unsigned long)sring, get_order(ring_size));
1675 rinfo->ring.sring = NULL;
1678 for (i = 0; i < info->nr_ring_pages; i++)
1679 rinfo->ring_ref[i] = gref[i];
1681 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1685 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1688 xenbus_dev_fatal(dev, err,
1689 "bind_evtchn_to_irqhandler failed");
1696 blkif_free(info, 0);
1701 * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1702 * ring buffer may have multi pages depending on ->nr_ring_pages.
1704 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1705 struct blkfront_ring_info *rinfo, const char *dir)
1709 const char *message = NULL;
1710 struct blkfront_info *info = rinfo->dev_info;
1712 if (info->nr_ring_pages == 1) {
1713 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1715 message = "writing ring-ref";
1716 goto abort_transaction;
1719 for (i = 0; i < info->nr_ring_pages; i++) {
1720 char ring_ref_name[RINGREF_NAME_LEN];
1722 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1723 err = xenbus_printf(xbt, dir, ring_ref_name,
1724 "%u", rinfo->ring_ref[i]);
1726 message = "writing ring-ref";
1727 goto abort_transaction;
1732 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1734 message = "writing event-channel";
1735 goto abort_transaction;
1741 xenbus_transaction_end(xbt, 1);
1743 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1748 /* Common code used when first setting up, and when resuming. */
1749 static int talk_to_blkback(struct xenbus_device *dev,
1750 struct blkfront_info *info)
1752 const char *message = NULL;
1753 struct xenbus_transaction xbt;
1755 unsigned int i, max_page_order = 0;
1756 unsigned int ring_page_order = 0;
1758 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1759 "max-ring-page-order", "%u", &max_page_order);
1761 info->nr_ring_pages = 1;
1763 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1764 info->nr_ring_pages = 1 << ring_page_order;
1767 for (i = 0; i < info->nr_rings; i++) {
1768 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1770 /* Create shared ring, alloc event channel. */
1771 err = setup_blkring(dev, rinfo);
1773 goto destroy_blkring;
1777 err = xenbus_transaction_start(&xbt);
1779 xenbus_dev_fatal(dev, err, "starting transaction");
1780 goto destroy_blkring;
1783 if (info->nr_ring_pages > 1) {
1784 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1787 message = "writing ring-page-order";
1788 goto abort_transaction;
1792 /* We already got the number of queues/rings in _probe */
1793 if (info->nr_rings == 1) {
1794 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1796 goto destroy_blkring;
1801 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1804 message = "writing multi-queue-num-queues";
1805 goto abort_transaction;
1808 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1809 path = kmalloc(pathsize, GFP_KERNEL);
1812 message = "ENOMEM while writing ring references";
1813 goto abort_transaction;
1816 for (i = 0; i < info->nr_rings; i++) {
1817 memset(path, 0, pathsize);
1818 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1819 err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1822 goto destroy_blkring;
1827 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1828 XEN_IO_PROTO_ABI_NATIVE);
1830 message = "writing protocol";
1831 goto abort_transaction;
1833 err = xenbus_printf(xbt, dev->nodename,
1834 "feature-persistent", "%u", 1);
1837 "writing persistent grants feature to xenbus");
1839 err = xenbus_transaction_end(xbt, 0);
1843 xenbus_dev_fatal(dev, err, "completing transaction");
1844 goto destroy_blkring;
1847 for (i = 0; i < info->nr_rings; i++) {
1849 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1851 for (j = 0; j < BLK_RING_SIZE(info); j++)
1852 rinfo->shadow[j].req.u.rw.id = j + 1;
1853 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1855 xenbus_switch_state(dev, XenbusStateInitialised);
1860 xenbus_transaction_end(xbt, 1);
1862 xenbus_dev_fatal(dev, err, "%s", message);
1864 blkif_free(info, 0);
1867 dev_set_drvdata(&dev->dev, NULL);
1872 static int negotiate_mq(struct blkfront_info *info)
1874 unsigned int backend_max_queues = 0;
1878 BUG_ON(info->nr_rings);
1880 /* Check if backend supports multiple queues. */
1881 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1882 "multi-queue-max-queues", "%u", &backend_max_queues);
1884 backend_max_queues = 1;
1886 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1887 /* We need at least one ring. */
1888 if (!info->nr_rings)
1891 info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
1893 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1897 for (i = 0; i < info->nr_rings; i++) {
1898 struct blkfront_ring_info *rinfo;
1900 rinfo = &info->rinfo[i];
1901 INIT_LIST_HEAD(&rinfo->indirect_pages);
1902 INIT_LIST_HEAD(&rinfo->grants);
1903 rinfo->dev_info = info;
1904 INIT_WORK(&rinfo->work, blkif_restart_queue);
1905 spin_lock_init(&rinfo->ring_lock);
1910 * Entry point to this code when a new device is created. Allocate the basic
1911 * structures and the ring buffer for communication with the backend, and
1912 * inform the backend of the appropriate details for those. Switch to
1913 * Initialised state.
1915 static int blkfront_probe(struct xenbus_device *dev,
1916 const struct xenbus_device_id *id)
1919 struct blkfront_info *info;
1921 /* FIXME: Use dynamic device id if this is not set. */
1922 err = xenbus_scanf(XBT_NIL, dev->nodename,
1923 "virtual-device", "%i", &vdevice);
1925 /* go looking in the extended area instead */
1926 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1929 xenbus_dev_fatal(dev, err, "reading virtual-device");
1934 if (xen_hvm_domain()) {
1937 /* no unplug has been done: do not hook devices != xen vbds */
1938 if (xen_has_pv_and_legacy_disk_devices()) {
1941 if (!VDEV_IS_EXTENDED(vdevice))
1942 major = BLKIF_MAJOR(vdevice);
1944 major = XENVBD_MAJOR;
1946 if (major != XENVBD_MAJOR) {
1948 "%s: HVM does not support vbd %d as xen block device\n",
1953 /* do not create a PV cdrom device if we are an HVM guest */
1954 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1957 if (strncmp(type, "cdrom", 5) == 0) {
1963 info = kzalloc(sizeof(*info), GFP_KERNEL);
1965 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1970 err = negotiate_mq(info);
1976 mutex_init(&info->mutex);
1977 info->vdevice = vdevice;
1978 info->connected = BLKIF_STATE_DISCONNECTED;
1980 /* Front end dir is a number, which is used as the id. */
1981 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1982 dev_set_drvdata(&dev->dev, info);
1987 static void split_bio_end(struct bio *bio)
1989 struct split_bio *split_bio = bio->bi_private;
1991 if (atomic_dec_and_test(&split_bio->pending)) {
1992 split_bio->bio->bi_phys_segments = 0;
1993 split_bio->bio->bi_error = bio->bi_error;
1994 bio_endio(split_bio->bio);
2000 static int blkif_recover(struct blkfront_info *info)
2002 unsigned int i, r_index;
2003 struct request *req, *n;
2005 struct bio *bio, *cloned_bio;
2006 unsigned int segs, offset;
2008 struct split_bio *split_bio;
2010 blkfront_gather_backend_features(info);
2011 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2012 blk_queue_max_segments(info->rq, segs);
2014 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2015 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2017 rc = blkfront_setup_indirect(rinfo);
2021 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2023 /* Now safe for us to use the shared ring */
2024 info->connected = BLKIF_STATE_CONNECTED;
2026 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2027 struct blkfront_ring_info *rinfo;
2029 rinfo = &info->rinfo[r_index];
2030 /* Kick any other new requests queued since we resumed */
2031 kick_pending_request_queues(rinfo);
2034 list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2035 /* Requeue pending requests (flush or discard) */
2036 list_del_init(&req->queuelist);
2037 BUG_ON(req->nr_phys_segments > segs);
2038 blk_mq_requeue_request(req);
2040 blk_mq_kick_requeue_list(info->rq);
2042 while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2043 /* Traverse the list of pending bios and re-queue them */
2044 if (bio_segments(bio) > segs) {
2046 * This bio has more segments than what we can
2047 * handle, we have to split it.
2049 pending = (bio_segments(bio) + segs - 1) / segs;
2050 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
2051 BUG_ON(split_bio == NULL);
2052 atomic_set(&split_bio->pending, pending);
2053 split_bio->bio = bio;
2054 for (i = 0; i < pending; i++) {
2055 offset = (i * segs * XEN_PAGE_SIZE) >> 9;
2056 size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9,
2057 (unsigned int)bio_sectors(bio) - offset);
2058 cloned_bio = bio_clone(bio, GFP_NOIO);
2059 BUG_ON(cloned_bio == NULL);
2060 bio_trim(cloned_bio, offset, size);
2061 cloned_bio->bi_private = split_bio;
2062 cloned_bio->bi_end_io = split_bio_end;
2063 submit_bio(cloned_bio);
2066 * Now we have to wait for all those smaller bios to
2067 * end, so we can also end the "parent" bio.
2071 /* We don't need to split this bio */
2079 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2080 * driver restart. We tear down our blkif structure and recreate it, but
2081 * leave the device-layer structures intact so that this is transparent to the
2082 * rest of the kernel.
2084 static int blkfront_resume(struct xenbus_device *dev)
2086 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2090 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2092 bio_list_init(&info->bio_list);
2093 INIT_LIST_HEAD(&info->requests);
2094 for (i = 0; i < info->nr_rings; i++) {
2095 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2096 struct bio_list merge_bio;
2097 struct blk_shadow *shadow = rinfo->shadow;
2099 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2101 if (!shadow[j].request)
2105 * Get the bios in the request so we can re-queue them.
2107 if (req_op(shadow[i].request) == REQ_OP_FLUSH ||
2108 req_op(shadow[i].request) == REQ_OP_DISCARD ||
2109 shadow[j].request->cmd_flags & (REQ_FUA | REQ_SECURE)) {
2112 * Flush operations don't contain bios, so
2113 * we need to requeue the whole request
2115 list_add(&shadow[j].request->queuelist, &info->requests);
2118 merge_bio.head = shadow[j].request->bio;
2119 merge_bio.tail = shadow[j].request->biotail;
2120 bio_list_merge(&info->bio_list, &merge_bio);
2121 shadow[j].request->bio = NULL;
2122 blk_mq_end_request(shadow[j].request, 0);
2126 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2128 err = negotiate_mq(info);
2132 err = talk_to_blkback(dev, info);
2134 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2137 * We have to wait for the backend to switch to
2138 * connected state, since we want to read which
2139 * features it supports.
2145 static void blkfront_closing(struct blkfront_info *info)
2147 struct xenbus_device *xbdev = info->xbdev;
2148 struct block_device *bdev = NULL;
2150 mutex_lock(&info->mutex);
2152 if (xbdev->state == XenbusStateClosing) {
2153 mutex_unlock(&info->mutex);
2158 bdev = bdget_disk(info->gd, 0);
2160 mutex_unlock(&info->mutex);
2163 xenbus_frontend_closed(xbdev);
2167 mutex_lock(&bdev->bd_mutex);
2169 if (bdev->bd_openers) {
2170 xenbus_dev_error(xbdev, -EBUSY,
2171 "Device in use; refusing to close");
2172 xenbus_switch_state(xbdev, XenbusStateClosing);
2174 xlvbd_release_gendisk(info);
2175 xenbus_frontend_closed(xbdev);
2178 mutex_unlock(&bdev->bd_mutex);
2182 static void blkfront_setup_discard(struct blkfront_info *info)
2185 unsigned int discard_granularity;
2186 unsigned int discard_alignment;
2187 unsigned int discard_secure;
2189 info->feature_discard = 1;
2190 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2191 "discard-granularity", "%u", &discard_granularity,
2192 "discard-alignment", "%u", &discard_alignment,
2195 info->discard_granularity = discard_granularity;
2196 info->discard_alignment = discard_alignment;
2198 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2199 "discard-secure", "%d", &discard_secure,
2202 info->feature_secdiscard = !!discard_secure;
2205 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2207 unsigned int psegs, grants;
2209 struct blkfront_info *info = rinfo->dev_info;
2211 if (info->max_indirect_segments == 0) {
2213 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2216 * When an extra req is required, the maximum
2217 * grants supported is related to the size of the
2218 * Linux block segment.
2220 grants = GRANTS_PER_PSEG;
2224 grants = info->max_indirect_segments;
2225 psegs = grants / GRANTS_PER_PSEG;
2227 err = fill_grant_buffer(rinfo,
2228 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2232 if (!info->feature_persistent && info->max_indirect_segments) {
2234 * We are using indirect descriptors but not persistent
2235 * grants, we need to allocate a set of pages that can be
2236 * used for mapping indirect grefs
2238 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2240 BUG_ON(!list_empty(&rinfo->indirect_pages));
2241 for (i = 0; i < num; i++) {
2242 struct page *indirect_page = alloc_page(GFP_NOIO);
2245 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2249 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2250 rinfo->shadow[i].grants_used = kzalloc(
2251 sizeof(rinfo->shadow[i].grants_used[0]) * grants,
2253 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO);
2254 if (info->max_indirect_segments)
2255 rinfo->shadow[i].indirect_grants = kzalloc(
2256 sizeof(rinfo->shadow[i].indirect_grants[0]) *
2257 INDIRECT_GREFS(grants),
2259 if ((rinfo->shadow[i].grants_used == NULL) ||
2260 (rinfo->shadow[i].sg == NULL) ||
2261 (info->max_indirect_segments &&
2262 (rinfo->shadow[i].indirect_grants == NULL)))
2264 sg_init_table(rinfo->shadow[i].sg, psegs);
2271 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2272 kfree(rinfo->shadow[i].grants_used);
2273 rinfo->shadow[i].grants_used = NULL;
2274 kfree(rinfo->shadow[i].sg);
2275 rinfo->shadow[i].sg = NULL;
2276 kfree(rinfo->shadow[i].indirect_grants);
2277 rinfo->shadow[i].indirect_grants = NULL;
2279 if (!list_empty(&rinfo->indirect_pages)) {
2280 struct page *indirect_page, *n;
2281 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2282 list_del(&indirect_page->lru);
2283 __free_page(indirect_page);
2290 * Gather all backend feature-*
2292 static void blkfront_gather_backend_features(struct blkfront_info *info)
2295 int barrier, flush, discard, persistent;
2296 unsigned int indirect_segments;
2298 info->feature_flush = 0;
2299 info->feature_fua = 0;
2301 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2302 "feature-barrier", "%d", &barrier,
2306 * If there's no "feature-barrier" defined, then it means
2307 * we're dealing with a very old backend which writes
2308 * synchronously; nothing to do.
2310 * If there are barriers, then we use flush.
2312 if (!err && barrier) {
2313 info->feature_flush = 1;
2314 info->feature_fua = 1;
2318 * And if there is "feature-flush-cache" use that above
2321 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2322 "feature-flush-cache", "%d", &flush,
2325 if (!err && flush) {
2326 info->feature_flush = 1;
2327 info->feature_fua = 0;
2330 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2331 "feature-discard", "%d", &discard,
2334 if (!err && discard)
2335 blkfront_setup_discard(info);
2337 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2338 "feature-persistent", "%u", &persistent,
2341 info->feature_persistent = 0;
2343 info->feature_persistent = persistent;
2345 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2346 "feature-max-indirect-segments", "%u", &indirect_segments,
2349 info->max_indirect_segments = 0;
2351 info->max_indirect_segments = min(indirect_segments,
2352 xen_blkif_max_segments);
2356 * Invoked when the backend is finally 'ready' (and has told produced
2357 * the details about the physical device - #sectors, size, etc).
2359 static void blkfront_connect(struct blkfront_info *info)
2361 unsigned long long sectors;
2362 unsigned long sector_size;
2363 unsigned int physical_sector_size;
2367 switch (info->connected) {
2368 case BLKIF_STATE_CONNECTED:
2370 * Potentially, the back-end may be signalling
2371 * a capacity change; update the capacity.
2373 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2374 "sectors", "%Lu", §ors);
2375 if (XENBUS_EXIST_ERR(err))
2377 printk(KERN_INFO "Setting capacity to %Lu\n",
2379 set_capacity(info->gd, sectors);
2380 revalidate_disk(info->gd);
2383 case BLKIF_STATE_SUSPENDED:
2385 * If we are recovering from suspension, we need to wait
2386 * for the backend to announce it's features before
2387 * reconnecting, at least we need to know if the backend
2388 * supports indirect descriptors, and how many.
2390 blkif_recover(info);
2397 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2398 __func__, info->xbdev->otherend);
2400 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2401 "sectors", "%llu", §ors,
2402 "info", "%u", &binfo,
2403 "sector-size", "%lu", §or_size,
2406 xenbus_dev_fatal(info->xbdev, err,
2407 "reading backend fields at %s",
2408 info->xbdev->otherend);
2413 * physcial-sector-size is a newer field, so old backends may not
2414 * provide this. Assume physical sector size to be the same as
2415 * sector_size in that case.
2417 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2418 "physical-sector-size", "%u", &physical_sector_size);
2420 physical_sector_size = sector_size;
2422 blkfront_gather_backend_features(info);
2423 for (i = 0; i < info->nr_rings; i++) {
2424 err = blkfront_setup_indirect(&info->rinfo[i]);
2426 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2427 info->xbdev->otherend);
2428 blkif_free(info, 0);
2433 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2434 physical_sector_size);
2436 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2437 info->xbdev->otherend);
2441 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2443 /* Kick pending requests. */
2444 info->connected = BLKIF_STATE_CONNECTED;
2445 for (i = 0; i < info->nr_rings; i++)
2446 kick_pending_request_queues(&info->rinfo[i]);
2454 * Callback received when the backend's state changes.
2456 static void blkback_changed(struct xenbus_device *dev,
2457 enum xenbus_state backend_state)
2459 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2461 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2463 switch (backend_state) {
2464 case XenbusStateInitWait:
2465 if (dev->state != XenbusStateInitialising)
2467 if (talk_to_blkback(dev, info))
2469 case XenbusStateInitialising:
2470 case XenbusStateInitialised:
2471 case XenbusStateReconfiguring:
2472 case XenbusStateReconfigured:
2473 case XenbusStateUnknown:
2476 case XenbusStateConnected:
2478 * talk_to_blkback sets state to XenbusStateInitialised
2479 * and blkfront_connect sets it to XenbusStateConnected
2480 * (if connection went OK).
2482 * If the backend (or toolstack) decides to poke at backend
2483 * state (and re-trigger the watch by setting the state repeatedly
2484 * to XenbusStateConnected (4)) we need to deal with this.
2485 * This is allowed as this is used to communicate to the guest
2486 * that the size of disk has changed!
2488 if ((dev->state != XenbusStateInitialised) &&
2489 (dev->state != XenbusStateConnected)) {
2490 if (talk_to_blkback(dev, info))
2494 blkfront_connect(info);
2497 case XenbusStateClosed:
2498 if (dev->state == XenbusStateClosed)
2500 /* Missed the backend's Closing state -- fallthrough */
2501 case XenbusStateClosing:
2503 blkfront_closing(info);
2508 static int blkfront_remove(struct xenbus_device *xbdev)
2510 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2511 struct block_device *bdev = NULL;
2512 struct gendisk *disk;
2514 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2516 blkif_free(info, 0);
2518 mutex_lock(&info->mutex);
2522 bdev = bdget_disk(disk, 0);
2525 mutex_unlock(&info->mutex);
2533 * The xbdev was removed before we reached the Closed
2534 * state. See if it's safe to remove the disk. If the bdev
2535 * isn't closed yet, we let release take care of it.
2538 mutex_lock(&bdev->bd_mutex);
2539 info = disk->private_data;
2541 dev_warn(disk_to_dev(disk),
2542 "%s was hot-unplugged, %d stale handles\n",
2543 xbdev->nodename, bdev->bd_openers);
2545 if (info && !bdev->bd_openers) {
2546 xlvbd_release_gendisk(info);
2547 disk->private_data = NULL;
2551 mutex_unlock(&bdev->bd_mutex);
2557 static int blkfront_is_ready(struct xenbus_device *dev)
2559 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2561 return info->is_ready && info->xbdev;
2564 static int blkif_open(struct block_device *bdev, fmode_t mode)
2566 struct gendisk *disk = bdev->bd_disk;
2567 struct blkfront_info *info;
2570 mutex_lock(&blkfront_mutex);
2572 info = disk->private_data;
2579 mutex_lock(&info->mutex);
2582 /* xbdev is closed */
2585 mutex_unlock(&info->mutex);
2588 mutex_unlock(&blkfront_mutex);
2592 static void blkif_release(struct gendisk *disk, fmode_t mode)
2594 struct blkfront_info *info = disk->private_data;
2595 struct block_device *bdev;
2596 struct xenbus_device *xbdev;
2598 mutex_lock(&blkfront_mutex);
2600 bdev = bdget_disk(disk, 0);
2603 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2606 if (bdev->bd_openers)
2610 * Check if we have been instructed to close. We will have
2611 * deferred this request, because the bdev was still open.
2614 mutex_lock(&info->mutex);
2615 xbdev = info->xbdev;
2617 if (xbdev && xbdev->state == XenbusStateClosing) {
2618 /* pending switch to state closed */
2619 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2620 xlvbd_release_gendisk(info);
2621 xenbus_frontend_closed(info->xbdev);
2624 mutex_unlock(&info->mutex);
2627 /* sudden device removal */
2628 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2629 xlvbd_release_gendisk(info);
2630 disk->private_data = NULL;
2637 mutex_unlock(&blkfront_mutex);
2640 static const struct block_device_operations xlvbd_block_fops =
2642 .owner = THIS_MODULE,
2644 .release = blkif_release,
2645 .getgeo = blkif_getgeo,
2646 .ioctl = blkif_ioctl,
2650 static const struct xenbus_device_id blkfront_ids[] = {
2655 static struct xenbus_driver blkfront_driver = {
2656 .ids = blkfront_ids,
2657 .probe = blkfront_probe,
2658 .remove = blkfront_remove,
2659 .resume = blkfront_resume,
2660 .otherend_changed = blkback_changed,
2661 .is_ready = blkfront_is_ready,
2664 static int __init xlblk_init(void)
2667 int nr_cpus = num_online_cpus();
2672 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2673 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2674 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2675 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2678 if (xen_blkif_max_queues > nr_cpus) {
2679 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2680 xen_blkif_max_queues, nr_cpus);
2681 xen_blkif_max_queues = nr_cpus;
2684 if (!xen_has_pv_disk_devices())
2687 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2688 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2689 XENVBD_MAJOR, DEV_NAME);
2693 ret = xenbus_register_frontend(&blkfront_driver);
2695 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2701 module_init(xlblk_init);
2704 static void __exit xlblk_exit(void)
2706 xenbus_unregister_driver(&blkfront_driver);
2707 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2710 module_exit(xlblk_exit);
2712 MODULE_DESCRIPTION("Xen virtual block device frontend");
2713 MODULE_LICENSE("GPL");
2714 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2715 MODULE_ALIAS("xen:vbd");
2716 MODULE_ALIAS("xenblk");