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_discard:1;
200 unsigned int feature_secdiscard:1;
201 unsigned int discard_granularity;
202 unsigned int discard_alignment;
203 unsigned int feature_persistent:1;
204 /* Number of 4KB segments handled */
205 unsigned int max_indirect_segments;
207 struct blk_mq_tag_set tag_set;
208 struct blkfront_ring_info *rinfo;
209 unsigned int nr_rings;
210 /* Save uncomplete reqs and bios for migration. */
211 struct list_head requests;
212 struct bio_list bio_list;
215 static unsigned int nr_minors;
216 static unsigned long *minors;
217 static DEFINE_SPINLOCK(minor_lock);
219 #define GRANT_INVALID_REF 0
221 #define PARTS_PER_DISK 16
222 #define PARTS_PER_EXT_DISK 256
224 #define BLKIF_MAJOR(dev) ((dev)>>8)
225 #define BLKIF_MINOR(dev) ((dev) & 0xff)
228 #define EXTENDED (1<<EXT_SHIFT)
229 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
230 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
231 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
232 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
233 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
234 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
236 #define DEV_NAME "xvd" /* name in /dev */
239 * Grants are always the same size as a Xen page (i.e 4KB).
240 * A physical segment is always the same size as a Linux page.
241 * Number of grants per physical segment
243 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
245 #define GRANTS_PER_INDIRECT_FRAME \
246 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
248 #define PSEGS_PER_INDIRECT_FRAME \
249 (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
251 #define INDIRECT_GREFS(_grants) \
252 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
254 #define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG)
256 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
257 static void blkfront_gather_backend_features(struct blkfront_info *info);
259 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
261 unsigned long free = rinfo->shadow_free;
263 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
264 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
265 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
269 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
272 if (rinfo->shadow[id].req.u.rw.id != id)
274 if (rinfo->shadow[id].request == NULL)
276 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
277 rinfo->shadow[id].request = NULL;
278 rinfo->shadow_free = id;
282 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
284 struct blkfront_info *info = rinfo->dev_info;
285 struct page *granted_page;
286 struct grant *gnt_list_entry, *n;
290 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
294 if (info->feature_persistent) {
295 granted_page = alloc_page(GFP_NOIO);
297 kfree(gnt_list_entry);
300 gnt_list_entry->page = granted_page;
303 gnt_list_entry->gref = GRANT_INVALID_REF;
304 list_add(&gnt_list_entry->node, &rinfo->grants);
311 list_for_each_entry_safe(gnt_list_entry, n,
312 &rinfo->grants, node) {
313 list_del(&gnt_list_entry->node);
314 if (info->feature_persistent)
315 __free_page(gnt_list_entry->page);
316 kfree(gnt_list_entry);
323 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
325 struct grant *gnt_list_entry;
327 BUG_ON(list_empty(&rinfo->grants));
328 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
330 list_del(&gnt_list_entry->node);
332 if (gnt_list_entry->gref != GRANT_INVALID_REF)
333 rinfo->persistent_gnts_c--;
335 return gnt_list_entry;
338 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
339 const struct blkfront_info *info)
341 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
342 info->xbdev->otherend_id,
343 gnt_list_entry->page,
347 static struct grant *get_grant(grant_ref_t *gref_head,
349 struct blkfront_ring_info *rinfo)
351 struct grant *gnt_list_entry = get_free_grant(rinfo);
352 struct blkfront_info *info = rinfo->dev_info;
354 if (gnt_list_entry->gref != GRANT_INVALID_REF)
355 return gnt_list_entry;
357 /* Assign a gref to this page */
358 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
359 BUG_ON(gnt_list_entry->gref == -ENOSPC);
360 if (info->feature_persistent)
361 grant_foreign_access(gnt_list_entry, info);
363 /* Grant access to the GFN passed by the caller */
364 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
365 info->xbdev->otherend_id,
369 return gnt_list_entry;
372 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
373 struct blkfront_ring_info *rinfo)
375 struct grant *gnt_list_entry = get_free_grant(rinfo);
376 struct blkfront_info *info = rinfo->dev_info;
378 if (gnt_list_entry->gref != GRANT_INVALID_REF)
379 return gnt_list_entry;
381 /* Assign a gref to this page */
382 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
383 BUG_ON(gnt_list_entry->gref == -ENOSPC);
384 if (!info->feature_persistent) {
385 struct page *indirect_page;
387 /* Fetch a pre-allocated page to use for indirect grefs */
388 BUG_ON(list_empty(&rinfo->indirect_pages));
389 indirect_page = list_first_entry(&rinfo->indirect_pages,
391 list_del(&indirect_page->lru);
392 gnt_list_entry->page = indirect_page;
394 grant_foreign_access(gnt_list_entry, info);
396 return gnt_list_entry;
399 static const char *op_name(int op)
401 static const char *const names[] = {
402 [BLKIF_OP_READ] = "read",
403 [BLKIF_OP_WRITE] = "write",
404 [BLKIF_OP_WRITE_BARRIER] = "barrier",
405 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
406 [BLKIF_OP_DISCARD] = "discard" };
408 if (op < 0 || op >= ARRAY_SIZE(names))
416 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
418 unsigned int end = minor + nr;
421 if (end > nr_minors) {
422 unsigned long *bitmap, *old;
424 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
429 spin_lock(&minor_lock);
430 if (end > nr_minors) {
432 memcpy(bitmap, minors,
433 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
435 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
438 spin_unlock(&minor_lock);
442 spin_lock(&minor_lock);
443 if (find_next_bit(minors, end, minor) >= end) {
444 bitmap_set(minors, minor, nr);
448 spin_unlock(&minor_lock);
453 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
455 unsigned int end = minor + nr;
457 BUG_ON(end > nr_minors);
458 spin_lock(&minor_lock);
459 bitmap_clear(minors, minor, nr);
460 spin_unlock(&minor_lock);
463 static void blkif_restart_queue_callback(void *arg)
465 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
466 schedule_work(&rinfo->work);
469 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
471 /* We don't have real geometry info, but let's at least return
472 values consistent with the size of the device */
473 sector_t nsect = get_capacity(bd->bd_disk);
474 sector_t cylinders = nsect;
478 sector_div(cylinders, hg->heads * hg->sectors);
479 hg->cylinders = cylinders;
480 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
481 hg->cylinders = 0xffff;
485 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
486 unsigned command, unsigned long argument)
488 struct blkfront_info *info = bdev->bd_disk->private_data;
491 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
492 command, (long)argument);
495 case CDROMMULTISESSION:
496 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
497 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
498 if (put_user(0, (char __user *)(argument + i)))
502 case CDROM_GET_CAPABILITY: {
503 struct gendisk *gd = info->gd;
504 if (gd->flags & GENHD_FL_CD)
510 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
512 return -EINVAL; /* same return as native Linux */
518 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
520 struct blkif_request **ring_req)
524 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
525 rinfo->ring.req_prod_pvt++;
527 id = get_id_from_freelist(rinfo);
528 rinfo->shadow[id].request = req;
529 rinfo->shadow[id].status = REQ_WAITING;
530 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
532 (*ring_req)->u.rw.id = id;
537 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
539 struct blkfront_info *info = rinfo->dev_info;
540 struct blkif_request *ring_req;
543 /* Fill out a communications ring structure. */
544 id = blkif_ring_get_request(rinfo, req, &ring_req);
546 ring_req->operation = BLKIF_OP_DISCARD;
547 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
548 ring_req->u.discard.id = id;
549 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
550 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
551 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
553 ring_req->u.discard.flag = 0;
555 /* Keep a private copy so we can reissue requests when recovering. */
556 rinfo->shadow[id].req = *ring_req;
561 struct setup_rw_req {
562 unsigned int grant_idx;
563 struct blkif_request_segment *segments;
564 struct blkfront_ring_info *rinfo;
565 struct blkif_request *ring_req;
566 grant_ref_t gref_head;
568 /* Only used when persistent grant is used and it's a read request */
570 unsigned int bvec_off;
573 bool require_extra_req;
574 struct blkif_request *extra_ring_req;
577 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
578 unsigned int len, void *data)
580 struct setup_rw_req *setup = data;
582 struct grant *gnt_list_entry;
583 unsigned int fsect, lsect;
584 /* Convenient aliases */
585 unsigned int grant_idx = setup->grant_idx;
586 struct blkif_request *ring_req = setup->ring_req;
587 struct blkfront_ring_info *rinfo = setup->rinfo;
589 * We always use the shadow of the first request to store the list
590 * of grant associated to the block I/O request. This made the
591 * completion more easy to handle even if the block I/O request is
594 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
596 if (unlikely(setup->require_extra_req &&
597 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
599 * We are using the second request, setup grant_idx
600 * to be the index of the segment array.
602 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
603 ring_req = setup->extra_ring_req;
606 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
607 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
609 kunmap_atomic(setup->segments);
611 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
612 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
613 shadow->indirect_grants[n] = gnt_list_entry;
614 setup->segments = kmap_atomic(gnt_list_entry->page);
615 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
618 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
619 ref = gnt_list_entry->gref;
621 * All the grants are stored in the shadow of the first
622 * request. Therefore we have to use the global index.
624 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
626 if (setup->need_copy) {
629 shared_data = kmap_atomic(gnt_list_entry->page);
631 * this does not wipe data stored outside the
632 * range sg->offset..sg->offset+sg->length.
633 * Therefore, blkback *could* see data from
634 * previous requests. This is OK as long as
635 * persistent grants are shared with just one
636 * domain. It may need refactoring if this
639 memcpy(shared_data + offset,
640 setup->bvec_data + setup->bvec_off,
643 kunmap_atomic(shared_data);
644 setup->bvec_off += len;
648 lsect = fsect + (len >> 9) - 1;
649 if (ring_req->operation != BLKIF_OP_INDIRECT) {
650 ring_req->u.rw.seg[grant_idx] =
651 (struct blkif_request_segment) {
654 .last_sect = lsect };
656 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
657 (struct blkif_request_segment) {
660 .last_sect = lsect };
663 (setup->grant_idx)++;
666 static void blkif_setup_extra_req(struct blkif_request *first,
667 struct blkif_request *second)
669 uint16_t nr_segments = first->u.rw.nr_segments;
672 * The second request is only present when the first request uses
673 * all its segments. It's always the continuity of the first one.
675 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
677 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
678 second->u.rw.sector_number = first->u.rw.sector_number +
679 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
681 second->u.rw.handle = first->u.rw.handle;
682 second->operation = first->operation;
685 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
687 struct blkfront_info *info = rinfo->dev_info;
688 struct blkif_request *ring_req, *extra_ring_req = NULL;
689 unsigned long id, extra_id = NO_ASSOCIATED_ID;
690 bool require_extra_req = false;
692 struct setup_rw_req setup = {
696 .need_copy = rq_data_dir(req) && info->feature_persistent,
700 * Used to store if we are able to queue the request by just using
701 * existing persistent grants, or if we have to get new grants,
702 * as there are not sufficiently many free.
704 struct scatterlist *sg;
705 int num_sg, max_grefs, num_grant;
707 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
708 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
710 * If we are using indirect segments we need to account
711 * for the indirect grefs used in the request.
713 max_grefs += INDIRECT_GREFS(max_grefs);
716 * We have to reserve 'max_grefs' grants because persistent
717 * grants are shared by all rings.
720 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) {
721 gnttab_request_free_callback(
723 blkif_restart_queue_callback,
729 /* Fill out a communications ring structure. */
730 id = blkif_ring_get_request(rinfo, req, &ring_req);
732 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
734 /* Calculate the number of grant used */
735 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
736 num_grant += gnttab_count_grant(sg->offset, sg->length);
738 require_extra_req = info->max_indirect_segments == 0 &&
739 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
740 BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
742 rinfo->shadow[id].num_sg = num_sg;
743 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
744 likely(!require_extra_req)) {
746 * The indirect operation can only be a BLKIF_OP_READ or
749 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
750 ring_req->operation = BLKIF_OP_INDIRECT;
751 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
752 BLKIF_OP_WRITE : BLKIF_OP_READ;
753 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
754 ring_req->u.indirect.handle = info->handle;
755 ring_req->u.indirect.nr_segments = num_grant;
757 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
758 ring_req->u.rw.handle = info->handle;
759 ring_req->operation = rq_data_dir(req) ?
760 BLKIF_OP_WRITE : BLKIF_OP_READ;
761 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
763 * Ideally we can do an unordered flush-to-disk.
764 * In case the backend onlysupports barriers, use that.
765 * A barrier request a superset of FUA, so we can
766 * implement it the same way. (It's also a FLUSH+FUA,
767 * since it is guaranteed ordered WRT previous writes.)
769 switch (info->feature_flush &
770 ((REQ_FLUSH|REQ_FUA))) {
771 case REQ_FLUSH|REQ_FUA:
772 ring_req->operation =
773 BLKIF_OP_WRITE_BARRIER;
776 ring_req->operation =
777 BLKIF_OP_FLUSH_DISKCACHE;
780 ring_req->operation = 0;
783 ring_req->u.rw.nr_segments = num_grant;
784 if (unlikely(require_extra_req)) {
785 extra_id = blkif_ring_get_request(rinfo, req,
788 * Only the first request contains the scatter-gather
791 rinfo->shadow[extra_id].num_sg = 0;
793 blkif_setup_extra_req(ring_req, extra_ring_req);
795 /* Link the 2 requests together */
796 rinfo->shadow[extra_id].associated_id = id;
797 rinfo->shadow[id].associated_id = extra_id;
801 setup.ring_req = ring_req;
804 setup.require_extra_req = require_extra_req;
805 if (unlikely(require_extra_req))
806 setup.extra_ring_req = extra_ring_req;
808 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
809 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
811 if (setup.need_copy) {
812 setup.bvec_off = sg->offset;
813 setup.bvec_data = kmap_atomic(sg_page(sg));
816 gnttab_foreach_grant_in_range(sg_page(sg),
819 blkif_setup_rw_req_grant,
823 kunmap_atomic(setup.bvec_data);
826 kunmap_atomic(setup.segments);
828 /* Keep a private copy so we can reissue requests when recovering. */
829 rinfo->shadow[id].req = *ring_req;
830 if (unlikely(require_extra_req))
831 rinfo->shadow[extra_id].req = *extra_ring_req;
834 gnttab_free_grant_references(setup.gref_head);
840 * Generate a Xen blkfront IO request from a blk layer request. Reads
841 * and writes are handled as expected.
843 * @req: a request struct
845 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
847 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
850 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE)))
851 return blkif_queue_discard_req(req, rinfo);
853 return blkif_queue_rw_req(req, rinfo);
856 static inline void flush_requests(struct blkfront_ring_info *rinfo)
860 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
863 notify_remote_via_irq(rinfo->irq);
866 static inline bool blkif_request_flush_invalid(struct request *req,
867 struct blkfront_info *info)
869 return ((req->cmd_type != REQ_TYPE_FS) ||
870 ((req->cmd_flags & REQ_FLUSH) &&
871 !(info->feature_flush & REQ_FLUSH)) ||
872 ((req->cmd_flags & REQ_FUA) &&
873 !(info->feature_flush & REQ_FUA)));
876 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
877 const struct blk_mq_queue_data *qd)
880 int qid = hctx->queue_num;
881 struct blkfront_info *info = hctx->queue->queuedata;
882 struct blkfront_ring_info *rinfo = NULL;
884 BUG_ON(info->nr_rings <= qid);
885 rinfo = &info->rinfo[qid];
886 blk_mq_start_request(qd->rq);
887 spin_lock_irqsave(&rinfo->ring_lock, flags);
888 if (RING_FULL(&rinfo->ring))
891 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
894 if (blkif_queue_request(qd->rq, rinfo))
897 flush_requests(rinfo);
898 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
899 return BLK_MQ_RQ_QUEUE_OK;
902 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
903 return BLK_MQ_RQ_QUEUE_ERROR;
906 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
907 blk_mq_stop_hw_queue(hctx);
908 return BLK_MQ_RQ_QUEUE_BUSY;
911 static struct blk_mq_ops blkfront_mq_ops = {
912 .queue_rq = blkif_queue_rq,
913 .map_queue = blk_mq_map_queue,
916 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
917 unsigned int physical_sector_size,
918 unsigned int segments)
920 struct request_queue *rq;
921 struct blkfront_info *info = gd->private_data;
923 memset(&info->tag_set, 0, sizeof(info->tag_set));
924 info->tag_set.ops = &blkfront_mq_ops;
925 info->tag_set.nr_hw_queues = info->nr_rings;
926 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
928 * When indirect descriptior is not supported, the I/O request
929 * will be split between multiple request in the ring.
930 * To avoid problems when sending the request, divide by
931 * 2 the depth of the queue.
933 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
935 info->tag_set.queue_depth = BLK_RING_SIZE(info);
936 info->tag_set.numa_node = NUMA_NO_NODE;
937 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
938 info->tag_set.cmd_size = 0;
939 info->tag_set.driver_data = info;
941 if (blk_mq_alloc_tag_set(&info->tag_set))
943 rq = blk_mq_init_queue(&info->tag_set);
945 blk_mq_free_tag_set(&info->tag_set);
949 rq->queuedata = info;
950 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
952 if (info->feature_discard) {
953 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
954 blk_queue_max_discard_sectors(rq, get_capacity(gd));
955 rq->limits.discard_granularity = info->discard_granularity;
956 rq->limits.discard_alignment = info->discard_alignment;
957 if (info->feature_secdiscard)
958 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
961 /* Hard sector size and max sectors impersonate the equiv. hardware. */
962 blk_queue_logical_block_size(rq, sector_size);
963 blk_queue_physical_block_size(rq, physical_sector_size);
964 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
966 /* Each segment in a request is up to an aligned page in size. */
967 blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
968 blk_queue_max_segment_size(rq, PAGE_SIZE);
970 /* Ensure a merged request will fit in a single I/O ring slot. */
971 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
973 /* Make sure buffer addresses are sector-aligned. */
974 blk_queue_dma_alignment(rq, 511);
976 /* Make sure we don't use bounce buffers. */
977 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
984 static const char *flush_info(unsigned int feature_flush)
986 switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) {
987 case REQ_FLUSH|REQ_FUA:
988 return "barrier: enabled;";
990 return "flush diskcache: enabled;";
992 return "barrier or flush: disabled;";
996 static void xlvbd_flush(struct blkfront_info *info)
998 blk_queue_write_cache(info->rq, info->feature_flush & REQ_FLUSH,
999 info->feature_flush & REQ_FUA);
1000 pr_info("blkfront: %s: %s %s %s %s %s\n",
1001 info->gd->disk_name, flush_info(info->feature_flush),
1002 "persistent grants:", info->feature_persistent ?
1003 "enabled;" : "disabled;", "indirect descriptors:",
1004 info->max_indirect_segments ? "enabled;" : "disabled;");
1007 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1010 major = BLKIF_MAJOR(vdevice);
1011 *minor = BLKIF_MINOR(vdevice);
1013 case XEN_IDE0_MAJOR:
1014 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1015 *minor = ((*minor / 64) * PARTS_PER_DISK) +
1016 EMULATED_HD_DISK_MINOR_OFFSET;
1018 case XEN_IDE1_MAJOR:
1019 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1020 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1021 EMULATED_HD_DISK_MINOR_OFFSET;
1023 case XEN_SCSI_DISK0_MAJOR:
1024 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1025 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1027 case XEN_SCSI_DISK1_MAJOR:
1028 case XEN_SCSI_DISK2_MAJOR:
1029 case XEN_SCSI_DISK3_MAJOR:
1030 case XEN_SCSI_DISK4_MAJOR:
1031 case XEN_SCSI_DISK5_MAJOR:
1032 case XEN_SCSI_DISK6_MAJOR:
1033 case XEN_SCSI_DISK7_MAJOR:
1034 *offset = (*minor / PARTS_PER_DISK) +
1035 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1036 EMULATED_SD_DISK_NAME_OFFSET;
1038 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1039 EMULATED_SD_DISK_MINOR_OFFSET;
1041 case XEN_SCSI_DISK8_MAJOR:
1042 case XEN_SCSI_DISK9_MAJOR:
1043 case XEN_SCSI_DISK10_MAJOR:
1044 case XEN_SCSI_DISK11_MAJOR:
1045 case XEN_SCSI_DISK12_MAJOR:
1046 case XEN_SCSI_DISK13_MAJOR:
1047 case XEN_SCSI_DISK14_MAJOR:
1048 case XEN_SCSI_DISK15_MAJOR:
1049 *offset = (*minor / PARTS_PER_DISK) +
1050 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1051 EMULATED_SD_DISK_NAME_OFFSET;
1053 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1054 EMULATED_SD_DISK_MINOR_OFFSET;
1057 *offset = *minor / PARTS_PER_DISK;
1060 printk(KERN_WARNING "blkfront: your disk configuration is "
1061 "incorrect, please use an xvd device instead\n");
1067 static char *encode_disk_name(char *ptr, unsigned int n)
1070 ptr = encode_disk_name(ptr, n / 26 - 1);
1071 *ptr = 'a' + n % 26;
1075 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1076 struct blkfront_info *info,
1077 u16 vdisk_info, u16 sector_size,
1078 unsigned int physical_sector_size)
1083 unsigned int offset;
1088 BUG_ON(info->gd != NULL);
1089 BUG_ON(info->rq != NULL);
1091 if ((info->vdevice>>EXT_SHIFT) > 1) {
1092 /* this is above the extended range; something is wrong */
1093 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1097 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1098 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1101 nr_parts = PARTS_PER_DISK;
1103 minor = BLKIF_MINOR_EXT(info->vdevice);
1104 nr_parts = PARTS_PER_EXT_DISK;
1105 offset = minor / nr_parts;
1106 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1107 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1108 "emulated IDE disks,\n\t choose an xvd device name"
1109 "from xvde on\n", info->vdevice);
1111 if (minor >> MINORBITS) {
1112 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1113 info->vdevice, minor);
1117 if ((minor % nr_parts) == 0)
1118 nr_minors = nr_parts;
1120 err = xlbd_reserve_minors(minor, nr_minors);
1125 gd = alloc_disk(nr_minors);
1129 strcpy(gd->disk_name, DEV_NAME);
1130 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1131 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1135 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1136 "%d", minor & (nr_parts - 1));
1138 gd->major = XENVBD_MAJOR;
1139 gd->first_minor = minor;
1140 gd->fops = &xlvbd_block_fops;
1141 gd->private_data = info;
1142 gd->driverfs_dev = &(info->xbdev->dev);
1143 set_capacity(gd, capacity);
1145 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
1146 info->max_indirect_segments ? :
1147 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
1152 info->rq = gd->queue;
1157 if (vdisk_info & VDISK_READONLY)
1160 if (vdisk_info & VDISK_REMOVABLE)
1161 gd->flags |= GENHD_FL_REMOVABLE;
1163 if (vdisk_info & VDISK_CDROM)
1164 gd->flags |= GENHD_FL_CD;
1169 xlbd_release_minors(minor, nr_minors);
1174 static void xlvbd_release_gendisk(struct blkfront_info *info)
1176 unsigned int minor, nr_minors, i;
1178 if (info->rq == NULL)
1181 /* No more blkif_request(). */
1182 blk_mq_stop_hw_queues(info->rq);
1184 for (i = 0; i < info->nr_rings; i++) {
1185 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1187 /* No more gnttab callback work. */
1188 gnttab_cancel_free_callback(&rinfo->callback);
1190 /* Flush gnttab callback work. Must be done with no locks held. */
1191 flush_work(&rinfo->work);
1194 del_gendisk(info->gd);
1196 minor = info->gd->first_minor;
1197 nr_minors = info->gd->minors;
1198 xlbd_release_minors(minor, nr_minors);
1200 blk_cleanup_queue(info->rq);
1201 blk_mq_free_tag_set(&info->tag_set);
1208 /* Already hold rinfo->ring_lock. */
1209 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1211 if (!RING_FULL(&rinfo->ring))
1212 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1215 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1217 unsigned long flags;
1219 spin_lock_irqsave(&rinfo->ring_lock, flags);
1220 kick_pending_request_queues_locked(rinfo);
1221 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1224 static void blkif_restart_queue(struct work_struct *work)
1226 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1228 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1229 kick_pending_request_queues(rinfo);
1232 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1234 struct grant *persistent_gnt, *n;
1235 struct blkfront_info *info = rinfo->dev_info;
1239 * Remove indirect pages, this only happens when using indirect
1240 * descriptors but not persistent grants
1242 if (!list_empty(&rinfo->indirect_pages)) {
1243 struct page *indirect_page, *n;
1245 BUG_ON(info->feature_persistent);
1246 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1247 list_del(&indirect_page->lru);
1248 __free_page(indirect_page);
1252 /* Remove all persistent grants. */
1253 if (!list_empty(&rinfo->grants)) {
1254 list_for_each_entry_safe(persistent_gnt, n,
1255 &rinfo->grants, node) {
1256 list_del(&persistent_gnt->node);
1257 if (persistent_gnt->gref != GRANT_INVALID_REF) {
1258 gnttab_end_foreign_access(persistent_gnt->gref,
1260 rinfo->persistent_gnts_c--;
1262 if (info->feature_persistent)
1263 __free_page(persistent_gnt->page);
1264 kfree(persistent_gnt);
1267 BUG_ON(rinfo->persistent_gnts_c != 0);
1269 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1271 * Clear persistent grants present in requests already
1272 * on the shared ring
1274 if (!rinfo->shadow[i].request)
1277 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1278 rinfo->shadow[i].req.u.indirect.nr_segments :
1279 rinfo->shadow[i].req.u.rw.nr_segments;
1280 for (j = 0; j < segs; j++) {
1281 persistent_gnt = rinfo->shadow[i].grants_used[j];
1282 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1283 if (info->feature_persistent)
1284 __free_page(persistent_gnt->page);
1285 kfree(persistent_gnt);
1288 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1290 * If this is not an indirect operation don't try to
1291 * free indirect segments
1295 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1296 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1297 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1298 __free_page(persistent_gnt->page);
1299 kfree(persistent_gnt);
1303 kfree(rinfo->shadow[i].grants_used);
1304 rinfo->shadow[i].grants_used = NULL;
1305 kfree(rinfo->shadow[i].indirect_grants);
1306 rinfo->shadow[i].indirect_grants = NULL;
1307 kfree(rinfo->shadow[i].sg);
1308 rinfo->shadow[i].sg = NULL;
1311 /* No more gnttab callback work. */
1312 gnttab_cancel_free_callback(&rinfo->callback);
1314 /* Flush gnttab callback work. Must be done with no locks held. */
1315 flush_work(&rinfo->work);
1317 /* Free resources associated with old device channel. */
1318 for (i = 0; i < info->nr_ring_pages; i++) {
1319 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1320 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1321 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1324 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE));
1325 rinfo->ring.sring = NULL;
1328 unbind_from_irqhandler(rinfo->irq, rinfo);
1329 rinfo->evtchn = rinfo->irq = 0;
1332 static void blkif_free(struct blkfront_info *info, int suspend)
1336 /* Prevent new requests being issued until we fix things up. */
1337 info->connected = suspend ?
1338 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1339 /* No more blkif_request(). */
1341 blk_mq_stop_hw_queues(info->rq);
1343 for (i = 0; i < info->nr_rings; i++)
1344 blkif_free_ring(&info->rinfo[i]);
1351 struct copy_from_grant {
1352 const struct blk_shadow *s;
1353 unsigned int grant_idx;
1354 unsigned int bvec_offset;
1358 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1359 unsigned int len, void *data)
1361 struct copy_from_grant *info = data;
1363 /* Convenient aliases */
1364 const struct blk_shadow *s = info->s;
1366 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1368 memcpy(info->bvec_data + info->bvec_offset,
1369 shared_data + offset, len);
1371 info->bvec_offset += len;
1374 kunmap_atomic(shared_data);
1377 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1381 case BLKIF_RSP_OKAY:
1383 case BLKIF_RSP_EOPNOTSUPP:
1384 return REQ_EOPNOTSUPP;
1385 case BLKIF_RSP_ERROR:
1393 * Get the final status of the block request based on two ring response
1395 static int blkif_get_final_status(enum blk_req_status s1,
1396 enum blk_req_status s2)
1398 BUG_ON(s1 == REQ_WAITING);
1399 BUG_ON(s2 == REQ_WAITING);
1401 if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1402 return BLKIF_RSP_ERROR;
1403 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1404 return BLKIF_RSP_EOPNOTSUPP;
1405 return BLKIF_RSP_OKAY;
1408 static bool blkif_completion(unsigned long *id,
1409 struct blkfront_ring_info *rinfo,
1410 struct blkif_response *bret)
1413 struct scatterlist *sg;
1414 int num_sg, num_grant;
1415 struct blkfront_info *info = rinfo->dev_info;
1416 struct blk_shadow *s = &rinfo->shadow[*id];
1417 struct copy_from_grant data = {
1421 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1422 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1424 /* The I/O request may be split in two. */
1425 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1426 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1428 /* Keep the status of the current response in shadow. */
1429 s->status = blkif_rsp_to_req_status(bret->status);
1431 /* Wait the second response if not yet here. */
1432 if (s2->status == REQ_WAITING)
1435 bret->status = blkif_get_final_status(s->status,
1439 * All the grants is stored in the first shadow in order
1440 * to make the completion code simpler.
1442 num_grant += s2->req.u.rw.nr_segments;
1445 * The two responses may not come in order. Only the
1446 * first request will store the scatter-gather list.
1448 if (s2->num_sg != 0) {
1449 /* Update "id" with the ID of the first response. */
1450 *id = s->associated_id;
1455 * We don't need anymore the second request, so recycling
1458 if (add_id_to_freelist(rinfo, s->associated_id))
1459 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1460 info->gd->disk_name, s->associated_id);
1466 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1467 for_each_sg(s->sg, sg, num_sg, i) {
1468 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1470 data.bvec_offset = sg->offset;
1471 data.bvec_data = kmap_atomic(sg_page(sg));
1473 gnttab_foreach_grant_in_range(sg_page(sg),
1476 blkif_copy_from_grant,
1479 kunmap_atomic(data.bvec_data);
1482 /* Add the persistent grant into the list of free grants */
1483 for (i = 0; i < num_grant; i++) {
1484 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1486 * If the grant is still mapped by the backend (the
1487 * backend has chosen to make this grant persistent)
1488 * we add it at the head of the list, so it will be
1491 if (!info->feature_persistent)
1492 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1493 s->grants_used[i]->gref);
1494 list_add(&s->grants_used[i]->node, &rinfo->grants);
1495 rinfo->persistent_gnts_c++;
1498 * If the grant is not mapped by the backend we end the
1499 * foreign access and add it to the tail of the list,
1500 * so it will not be picked again unless we run out of
1501 * persistent grants.
1503 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1504 s->grants_used[i]->gref = GRANT_INVALID_REF;
1505 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1508 if (s->req.operation == BLKIF_OP_INDIRECT) {
1509 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1510 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1511 if (!info->feature_persistent)
1512 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1513 s->indirect_grants[i]->gref);
1514 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1515 rinfo->persistent_gnts_c++;
1517 struct page *indirect_page;
1519 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1521 * Add the used indirect page back to the list of
1522 * available pages for indirect grefs.
1524 if (!info->feature_persistent) {
1525 indirect_page = s->indirect_grants[i]->page;
1526 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1528 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1529 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1537 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1539 struct request *req;
1540 struct blkif_response *bret;
1542 unsigned long flags;
1543 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1544 struct blkfront_info *info = rinfo->dev_info;
1547 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1550 spin_lock_irqsave(&rinfo->ring_lock, flags);
1552 rp = rinfo->ring.sring->rsp_prod;
1553 rmb(); /* Ensure we see queued responses up to 'rp'. */
1555 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1558 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1561 * The backend has messed up and given us an id that we would
1562 * never have given to it (we stamp it up to BLK_RING_SIZE -
1563 * look in get_id_from_freelist.
1565 if (id >= BLK_RING_SIZE(info)) {
1566 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1567 info->gd->disk_name, op_name(bret->operation), id);
1568 /* We can't safely get the 'struct request' as
1569 * the id is busted. */
1572 req = rinfo->shadow[id].request;
1574 if (bret->operation != BLKIF_OP_DISCARD) {
1576 * We may need to wait for an extra response if the
1577 * I/O request is split in 2
1579 if (!blkif_completion(&id, rinfo, bret))
1583 if (add_id_to_freelist(rinfo, id)) {
1584 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1585 info->gd->disk_name, op_name(bret->operation), id);
1589 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1590 switch (bret->operation) {
1591 case BLKIF_OP_DISCARD:
1592 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1593 struct request_queue *rq = info->rq;
1594 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1595 info->gd->disk_name, op_name(bret->operation));
1596 error = -EOPNOTSUPP;
1597 info->feature_discard = 0;
1598 info->feature_secdiscard = 0;
1599 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1600 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1602 blk_mq_complete_request(req, error);
1604 case BLKIF_OP_FLUSH_DISKCACHE:
1605 case BLKIF_OP_WRITE_BARRIER:
1606 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1607 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1608 info->gd->disk_name, op_name(bret->operation));
1609 error = -EOPNOTSUPP;
1611 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1612 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1613 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1614 info->gd->disk_name, op_name(bret->operation));
1615 error = -EOPNOTSUPP;
1617 if (unlikely(error)) {
1618 if (error == -EOPNOTSUPP)
1620 info->feature_flush = 0;
1625 case BLKIF_OP_WRITE:
1626 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1627 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1628 "request: %x\n", bret->status);
1630 blk_mq_complete_request(req, error);
1637 rinfo->ring.rsp_cons = i;
1639 if (i != rinfo->ring.req_prod_pvt) {
1641 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1645 rinfo->ring.sring->rsp_event = i + 1;
1647 kick_pending_request_queues_locked(rinfo);
1649 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1655 static int setup_blkring(struct xenbus_device *dev,
1656 struct blkfront_ring_info *rinfo)
1658 struct blkif_sring *sring;
1660 struct blkfront_info *info = rinfo->dev_info;
1661 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1662 grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1664 for (i = 0; i < info->nr_ring_pages; i++)
1665 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1667 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1668 get_order(ring_size));
1670 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1673 SHARED_RING_INIT(sring);
1674 FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1676 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1678 free_pages((unsigned long)sring, get_order(ring_size));
1679 rinfo->ring.sring = NULL;
1682 for (i = 0; i < info->nr_ring_pages; i++)
1683 rinfo->ring_ref[i] = gref[i];
1685 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1689 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1692 xenbus_dev_fatal(dev, err,
1693 "bind_evtchn_to_irqhandler failed");
1700 blkif_free(info, 0);
1705 * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1706 * ring buffer may have multi pages depending on ->nr_ring_pages.
1708 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1709 struct blkfront_ring_info *rinfo, const char *dir)
1713 const char *message = NULL;
1714 struct blkfront_info *info = rinfo->dev_info;
1716 if (info->nr_ring_pages == 1) {
1717 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1719 message = "writing ring-ref";
1720 goto abort_transaction;
1723 for (i = 0; i < info->nr_ring_pages; i++) {
1724 char ring_ref_name[RINGREF_NAME_LEN];
1726 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1727 err = xenbus_printf(xbt, dir, ring_ref_name,
1728 "%u", rinfo->ring_ref[i]);
1730 message = "writing ring-ref";
1731 goto abort_transaction;
1736 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1738 message = "writing event-channel";
1739 goto abort_transaction;
1745 xenbus_transaction_end(xbt, 1);
1747 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1752 /* Common code used when first setting up, and when resuming. */
1753 static int talk_to_blkback(struct xenbus_device *dev,
1754 struct blkfront_info *info)
1756 const char *message = NULL;
1757 struct xenbus_transaction xbt;
1759 unsigned int i, max_page_order = 0;
1760 unsigned int ring_page_order = 0;
1762 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1763 "max-ring-page-order", "%u", &max_page_order);
1765 info->nr_ring_pages = 1;
1767 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1768 info->nr_ring_pages = 1 << ring_page_order;
1771 for (i = 0; i < info->nr_rings; i++) {
1772 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1774 /* Create shared ring, alloc event channel. */
1775 err = setup_blkring(dev, rinfo);
1777 goto destroy_blkring;
1781 err = xenbus_transaction_start(&xbt);
1783 xenbus_dev_fatal(dev, err, "starting transaction");
1784 goto destroy_blkring;
1787 if (info->nr_ring_pages > 1) {
1788 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1791 message = "writing ring-page-order";
1792 goto abort_transaction;
1796 /* We already got the number of queues/rings in _probe */
1797 if (info->nr_rings == 1) {
1798 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1800 goto destroy_blkring;
1805 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1808 message = "writing multi-queue-num-queues";
1809 goto abort_transaction;
1812 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1813 path = kmalloc(pathsize, GFP_KERNEL);
1816 message = "ENOMEM while writing ring references";
1817 goto abort_transaction;
1820 for (i = 0; i < info->nr_rings; i++) {
1821 memset(path, 0, pathsize);
1822 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1823 err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1826 goto destroy_blkring;
1831 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1832 XEN_IO_PROTO_ABI_NATIVE);
1834 message = "writing protocol";
1835 goto abort_transaction;
1837 err = xenbus_printf(xbt, dev->nodename,
1838 "feature-persistent", "%u", 1);
1841 "writing persistent grants feature to xenbus");
1843 err = xenbus_transaction_end(xbt, 0);
1847 xenbus_dev_fatal(dev, err, "completing transaction");
1848 goto destroy_blkring;
1851 for (i = 0; i < info->nr_rings; i++) {
1853 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1855 for (j = 0; j < BLK_RING_SIZE(info); j++)
1856 rinfo->shadow[j].req.u.rw.id = j + 1;
1857 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1859 xenbus_switch_state(dev, XenbusStateInitialised);
1864 xenbus_transaction_end(xbt, 1);
1866 xenbus_dev_fatal(dev, err, "%s", message);
1868 blkif_free(info, 0);
1871 dev_set_drvdata(&dev->dev, NULL);
1876 static int negotiate_mq(struct blkfront_info *info)
1878 unsigned int backend_max_queues = 0;
1882 BUG_ON(info->nr_rings);
1884 /* Check if backend supports multiple queues. */
1885 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1886 "multi-queue-max-queues", "%u", &backend_max_queues);
1888 backend_max_queues = 1;
1890 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1891 /* We need at least one ring. */
1892 if (!info->nr_rings)
1895 info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
1897 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1901 for (i = 0; i < info->nr_rings; i++) {
1902 struct blkfront_ring_info *rinfo;
1904 rinfo = &info->rinfo[i];
1905 INIT_LIST_HEAD(&rinfo->indirect_pages);
1906 INIT_LIST_HEAD(&rinfo->grants);
1907 rinfo->dev_info = info;
1908 INIT_WORK(&rinfo->work, blkif_restart_queue);
1909 spin_lock_init(&rinfo->ring_lock);
1914 * Entry point to this code when a new device is created. Allocate the basic
1915 * structures and the ring buffer for communication with the backend, and
1916 * inform the backend of the appropriate details for those. Switch to
1917 * Initialised state.
1919 static int blkfront_probe(struct xenbus_device *dev,
1920 const struct xenbus_device_id *id)
1923 struct blkfront_info *info;
1925 /* FIXME: Use dynamic device id if this is not set. */
1926 err = xenbus_scanf(XBT_NIL, dev->nodename,
1927 "virtual-device", "%i", &vdevice);
1929 /* go looking in the extended area instead */
1930 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1933 xenbus_dev_fatal(dev, err, "reading virtual-device");
1938 if (xen_hvm_domain()) {
1941 /* no unplug has been done: do not hook devices != xen vbds */
1942 if (xen_has_pv_and_legacy_disk_devices()) {
1945 if (!VDEV_IS_EXTENDED(vdevice))
1946 major = BLKIF_MAJOR(vdevice);
1948 major = XENVBD_MAJOR;
1950 if (major != XENVBD_MAJOR) {
1952 "%s: HVM does not support vbd %d as xen block device\n",
1957 /* do not create a PV cdrom device if we are an HVM guest */
1958 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1961 if (strncmp(type, "cdrom", 5) == 0) {
1967 info = kzalloc(sizeof(*info), GFP_KERNEL);
1969 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1974 err = negotiate_mq(info);
1980 mutex_init(&info->mutex);
1981 info->vdevice = vdevice;
1982 info->connected = BLKIF_STATE_DISCONNECTED;
1984 /* Front end dir is a number, which is used as the id. */
1985 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1986 dev_set_drvdata(&dev->dev, info);
1991 static void split_bio_end(struct bio *bio)
1993 struct split_bio *split_bio = bio->bi_private;
1995 if (atomic_dec_and_test(&split_bio->pending)) {
1996 split_bio->bio->bi_phys_segments = 0;
1997 split_bio->bio->bi_error = bio->bi_error;
1998 bio_endio(split_bio->bio);
2004 static int blkif_recover(struct blkfront_info *info)
2006 unsigned int i, r_index;
2007 struct request *req, *n;
2009 struct bio *bio, *cloned_bio;
2010 unsigned int segs, offset;
2012 struct split_bio *split_bio;
2014 blkfront_gather_backend_features(info);
2015 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2016 blk_queue_max_segments(info->rq, segs);
2018 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2019 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2021 rc = blkfront_setup_indirect(rinfo);
2025 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2027 /* Now safe for us to use the shared ring */
2028 info->connected = BLKIF_STATE_CONNECTED;
2030 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2031 struct blkfront_ring_info *rinfo;
2033 rinfo = &info->rinfo[r_index];
2034 /* Kick any other new requests queued since we resumed */
2035 kick_pending_request_queues(rinfo);
2038 list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2039 /* Requeue pending requests (flush or discard) */
2040 list_del_init(&req->queuelist);
2041 BUG_ON(req->nr_phys_segments > segs);
2042 blk_mq_requeue_request(req);
2044 blk_mq_kick_requeue_list(info->rq);
2046 while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2047 /* Traverse the list of pending bios and re-queue them */
2048 if (bio_segments(bio) > segs) {
2050 * This bio has more segments than what we can
2051 * handle, we have to split it.
2053 pending = (bio_segments(bio) + segs - 1) / segs;
2054 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
2055 BUG_ON(split_bio == NULL);
2056 atomic_set(&split_bio->pending, pending);
2057 split_bio->bio = bio;
2058 for (i = 0; i < pending; i++) {
2059 offset = (i * segs * XEN_PAGE_SIZE) >> 9;
2060 size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9,
2061 (unsigned int)bio_sectors(bio) - offset);
2062 cloned_bio = bio_clone(bio, GFP_NOIO);
2063 BUG_ON(cloned_bio == NULL);
2064 bio_trim(cloned_bio, offset, size);
2065 cloned_bio->bi_private = split_bio;
2066 cloned_bio->bi_end_io = split_bio_end;
2067 submit_bio(cloned_bio->bi_rw, cloned_bio);
2070 * Now we have to wait for all those smaller bios to
2071 * end, so we can also end the "parent" bio.
2075 /* We don't need to split this bio */
2076 submit_bio(bio->bi_rw, bio);
2083 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2084 * driver restart. We tear down our blkif structure and recreate it, but
2085 * leave the device-layer structures intact so that this is transparent to the
2086 * rest of the kernel.
2088 static int blkfront_resume(struct xenbus_device *dev)
2090 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2094 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2096 bio_list_init(&info->bio_list);
2097 INIT_LIST_HEAD(&info->requests);
2098 for (i = 0; i < info->nr_rings; i++) {
2099 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2100 struct bio_list merge_bio;
2101 struct blk_shadow *shadow = rinfo->shadow;
2103 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2105 if (!shadow[j].request)
2109 * Get the bios in the request so we can re-queue them.
2111 if (shadow[j].request->cmd_flags &
2112 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
2114 * Flush operations don't contain bios, so
2115 * we need to requeue the whole request
2117 list_add(&shadow[j].request->queuelist, &info->requests);
2120 merge_bio.head = shadow[j].request->bio;
2121 merge_bio.tail = shadow[j].request->biotail;
2122 bio_list_merge(&info->bio_list, &merge_bio);
2123 shadow[j].request->bio = NULL;
2124 blk_mq_end_request(shadow[j].request, 0);
2128 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2130 err = negotiate_mq(info);
2134 err = talk_to_blkback(dev, info);
2136 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2139 * We have to wait for the backend to switch to
2140 * connected state, since we want to read which
2141 * features it supports.
2147 static void blkfront_closing(struct blkfront_info *info)
2149 struct xenbus_device *xbdev = info->xbdev;
2150 struct block_device *bdev = NULL;
2152 mutex_lock(&info->mutex);
2154 if (xbdev->state == XenbusStateClosing) {
2155 mutex_unlock(&info->mutex);
2160 bdev = bdget_disk(info->gd, 0);
2162 mutex_unlock(&info->mutex);
2165 xenbus_frontend_closed(xbdev);
2169 mutex_lock(&bdev->bd_mutex);
2171 if (bdev->bd_openers) {
2172 xenbus_dev_error(xbdev, -EBUSY,
2173 "Device in use; refusing to close");
2174 xenbus_switch_state(xbdev, XenbusStateClosing);
2176 xlvbd_release_gendisk(info);
2177 xenbus_frontend_closed(xbdev);
2180 mutex_unlock(&bdev->bd_mutex);
2184 static void blkfront_setup_discard(struct blkfront_info *info)
2187 unsigned int discard_granularity;
2188 unsigned int discard_alignment;
2189 unsigned int discard_secure;
2191 info->feature_discard = 1;
2192 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2193 "discard-granularity", "%u", &discard_granularity,
2194 "discard-alignment", "%u", &discard_alignment,
2197 info->discard_granularity = discard_granularity;
2198 info->discard_alignment = discard_alignment;
2200 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2201 "discard-secure", "%d", &discard_secure,
2204 info->feature_secdiscard = !!discard_secure;
2207 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2209 unsigned int psegs, grants;
2211 struct blkfront_info *info = rinfo->dev_info;
2213 if (info->max_indirect_segments == 0) {
2215 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2218 * When an extra req is required, the maximum
2219 * grants supported is related to the size of the
2220 * Linux block segment.
2222 grants = GRANTS_PER_PSEG;
2226 grants = info->max_indirect_segments;
2227 psegs = grants / GRANTS_PER_PSEG;
2229 err = fill_grant_buffer(rinfo,
2230 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2234 if (!info->feature_persistent && info->max_indirect_segments) {
2236 * We are using indirect descriptors but not persistent
2237 * grants, we need to allocate a set of pages that can be
2238 * used for mapping indirect grefs
2240 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2242 BUG_ON(!list_empty(&rinfo->indirect_pages));
2243 for (i = 0; i < num; i++) {
2244 struct page *indirect_page = alloc_page(GFP_NOIO);
2247 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2251 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2252 rinfo->shadow[i].grants_used = kzalloc(
2253 sizeof(rinfo->shadow[i].grants_used[0]) * grants,
2255 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO);
2256 if (info->max_indirect_segments)
2257 rinfo->shadow[i].indirect_grants = kzalloc(
2258 sizeof(rinfo->shadow[i].indirect_grants[0]) *
2259 INDIRECT_GREFS(grants),
2261 if ((rinfo->shadow[i].grants_used == NULL) ||
2262 (rinfo->shadow[i].sg == NULL) ||
2263 (info->max_indirect_segments &&
2264 (rinfo->shadow[i].indirect_grants == NULL)))
2266 sg_init_table(rinfo->shadow[i].sg, psegs);
2273 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2274 kfree(rinfo->shadow[i].grants_used);
2275 rinfo->shadow[i].grants_used = NULL;
2276 kfree(rinfo->shadow[i].sg);
2277 rinfo->shadow[i].sg = NULL;
2278 kfree(rinfo->shadow[i].indirect_grants);
2279 rinfo->shadow[i].indirect_grants = NULL;
2281 if (!list_empty(&rinfo->indirect_pages)) {
2282 struct page *indirect_page, *n;
2283 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2284 list_del(&indirect_page->lru);
2285 __free_page(indirect_page);
2292 * Gather all backend feature-*
2294 static void blkfront_gather_backend_features(struct blkfront_info *info)
2297 int barrier, flush, discard, persistent;
2298 unsigned int indirect_segments;
2300 info->feature_flush = 0;
2302 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2303 "feature-barrier", "%d", &barrier,
2307 * If there's no "feature-barrier" defined, then it means
2308 * we're dealing with a very old backend which writes
2309 * synchronously; nothing to do.
2311 * If there are barriers, then we use flush.
2313 if (!err && barrier)
2314 info->feature_flush = REQ_FLUSH | REQ_FUA;
2316 * And if there is "feature-flush-cache" use that above
2319 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2320 "feature-flush-cache", "%d", &flush,
2324 info->feature_flush = REQ_FLUSH;
2326 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2327 "feature-discard", "%d", &discard,
2330 if (!err && discard)
2331 blkfront_setup_discard(info);
2333 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2334 "feature-persistent", "%u", &persistent,
2337 info->feature_persistent = 0;
2339 info->feature_persistent = persistent;
2341 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2342 "feature-max-indirect-segments", "%u", &indirect_segments,
2345 info->max_indirect_segments = 0;
2347 info->max_indirect_segments = min(indirect_segments,
2348 xen_blkif_max_segments);
2352 * Invoked when the backend is finally 'ready' (and has told produced
2353 * the details about the physical device - #sectors, size, etc).
2355 static void blkfront_connect(struct blkfront_info *info)
2357 unsigned long long sectors;
2358 unsigned long sector_size;
2359 unsigned int physical_sector_size;
2363 switch (info->connected) {
2364 case BLKIF_STATE_CONNECTED:
2366 * Potentially, the back-end may be signalling
2367 * a capacity change; update the capacity.
2369 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2370 "sectors", "%Lu", §ors);
2371 if (XENBUS_EXIST_ERR(err))
2373 printk(KERN_INFO "Setting capacity to %Lu\n",
2375 set_capacity(info->gd, sectors);
2376 revalidate_disk(info->gd);
2379 case BLKIF_STATE_SUSPENDED:
2381 * If we are recovering from suspension, we need to wait
2382 * for the backend to announce it's features before
2383 * reconnecting, at least we need to know if the backend
2384 * supports indirect descriptors, and how many.
2386 blkif_recover(info);
2393 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2394 __func__, info->xbdev->otherend);
2396 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2397 "sectors", "%llu", §ors,
2398 "info", "%u", &binfo,
2399 "sector-size", "%lu", §or_size,
2402 xenbus_dev_fatal(info->xbdev, err,
2403 "reading backend fields at %s",
2404 info->xbdev->otherend);
2409 * physcial-sector-size is a newer field, so old backends may not
2410 * provide this. Assume physical sector size to be the same as
2411 * sector_size in that case.
2413 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2414 "physical-sector-size", "%u", &physical_sector_size);
2416 physical_sector_size = sector_size;
2418 blkfront_gather_backend_features(info);
2419 for (i = 0; i < info->nr_rings; i++) {
2420 err = blkfront_setup_indirect(&info->rinfo[i]);
2422 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2423 info->xbdev->otherend);
2424 blkif_free(info, 0);
2429 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2430 physical_sector_size);
2432 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2433 info->xbdev->otherend);
2437 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2439 /* Kick pending requests. */
2440 info->connected = BLKIF_STATE_CONNECTED;
2441 for (i = 0; i < info->nr_rings; i++)
2442 kick_pending_request_queues(&info->rinfo[i]);
2450 * Callback received when the backend's state changes.
2452 static void blkback_changed(struct xenbus_device *dev,
2453 enum xenbus_state backend_state)
2455 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2457 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2459 switch (backend_state) {
2460 case XenbusStateInitWait:
2461 if (dev->state != XenbusStateInitialising)
2463 if (talk_to_blkback(dev, info))
2465 case XenbusStateInitialising:
2466 case XenbusStateInitialised:
2467 case XenbusStateReconfiguring:
2468 case XenbusStateReconfigured:
2469 case XenbusStateUnknown:
2472 case XenbusStateConnected:
2474 * talk_to_blkback sets state to XenbusStateInitialised
2475 * and blkfront_connect sets it to XenbusStateConnected
2476 * (if connection went OK).
2478 * If the backend (or toolstack) decides to poke at backend
2479 * state (and re-trigger the watch by setting the state repeatedly
2480 * to XenbusStateConnected (4)) we need to deal with this.
2481 * This is allowed as this is used to communicate to the guest
2482 * that the size of disk has changed!
2484 if ((dev->state != XenbusStateInitialised) &&
2485 (dev->state != XenbusStateConnected)) {
2486 if (talk_to_blkback(dev, info))
2490 blkfront_connect(info);
2493 case XenbusStateClosed:
2494 if (dev->state == XenbusStateClosed)
2496 /* Missed the backend's Closing state -- fallthrough */
2497 case XenbusStateClosing:
2499 blkfront_closing(info);
2504 static int blkfront_remove(struct xenbus_device *xbdev)
2506 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2507 struct block_device *bdev = NULL;
2508 struct gendisk *disk;
2510 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2512 blkif_free(info, 0);
2514 mutex_lock(&info->mutex);
2518 bdev = bdget_disk(disk, 0);
2521 mutex_unlock(&info->mutex);
2529 * The xbdev was removed before we reached the Closed
2530 * state. See if it's safe to remove the disk. If the bdev
2531 * isn't closed yet, we let release take care of it.
2534 mutex_lock(&bdev->bd_mutex);
2535 info = disk->private_data;
2537 dev_warn(disk_to_dev(disk),
2538 "%s was hot-unplugged, %d stale handles\n",
2539 xbdev->nodename, bdev->bd_openers);
2541 if (info && !bdev->bd_openers) {
2542 xlvbd_release_gendisk(info);
2543 disk->private_data = NULL;
2547 mutex_unlock(&bdev->bd_mutex);
2553 static int blkfront_is_ready(struct xenbus_device *dev)
2555 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2557 return info->is_ready && info->xbdev;
2560 static int blkif_open(struct block_device *bdev, fmode_t mode)
2562 struct gendisk *disk = bdev->bd_disk;
2563 struct blkfront_info *info;
2566 mutex_lock(&blkfront_mutex);
2568 info = disk->private_data;
2575 mutex_lock(&info->mutex);
2578 /* xbdev is closed */
2581 mutex_unlock(&info->mutex);
2584 mutex_unlock(&blkfront_mutex);
2588 static void blkif_release(struct gendisk *disk, fmode_t mode)
2590 struct blkfront_info *info = disk->private_data;
2591 struct block_device *bdev;
2592 struct xenbus_device *xbdev;
2594 mutex_lock(&blkfront_mutex);
2596 bdev = bdget_disk(disk, 0);
2599 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2602 if (bdev->bd_openers)
2606 * Check if we have been instructed to close. We will have
2607 * deferred this request, because the bdev was still open.
2610 mutex_lock(&info->mutex);
2611 xbdev = info->xbdev;
2613 if (xbdev && xbdev->state == XenbusStateClosing) {
2614 /* pending switch to state closed */
2615 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2616 xlvbd_release_gendisk(info);
2617 xenbus_frontend_closed(info->xbdev);
2620 mutex_unlock(&info->mutex);
2623 /* sudden device removal */
2624 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2625 xlvbd_release_gendisk(info);
2626 disk->private_data = NULL;
2633 mutex_unlock(&blkfront_mutex);
2636 static const struct block_device_operations xlvbd_block_fops =
2638 .owner = THIS_MODULE,
2640 .release = blkif_release,
2641 .getgeo = blkif_getgeo,
2642 .ioctl = blkif_ioctl,
2646 static const struct xenbus_device_id blkfront_ids[] = {
2651 static struct xenbus_driver blkfront_driver = {
2652 .ids = blkfront_ids,
2653 .probe = blkfront_probe,
2654 .remove = blkfront_remove,
2655 .resume = blkfront_resume,
2656 .otherend_changed = blkback_changed,
2657 .is_ready = blkfront_is_ready,
2660 static int __init xlblk_init(void)
2663 int nr_cpus = num_online_cpus();
2668 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2669 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2670 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2671 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2674 if (xen_blkif_max_queues > nr_cpus) {
2675 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2676 xen_blkif_max_queues, nr_cpus);
2677 xen_blkif_max_queues = nr_cpus;
2680 if (!xen_has_pv_disk_devices())
2683 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2684 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2685 XENVBD_MAJOR, DEV_NAME);
2689 ret = xenbus_register_frontend(&blkfront_driver);
2691 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2697 module_init(xlblk_init);
2700 static void __exit xlblk_exit(void)
2702 xenbus_unregister_driver(&blkfront_driver);
2703 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2706 module_exit(xlblk_exit);
2708 MODULE_DESCRIPTION("Xen virtual block device frontend");
2709 MODULE_LICENSE("GPL");
2710 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2711 MODULE_ALIAS("xen:vbd");
2712 MODULE_ALIAS("xenblk");