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;
212 static unsigned int nr_minors;
213 static unsigned long *minors;
214 static DEFINE_SPINLOCK(minor_lock);
216 #define GRANT_INVALID_REF 0
218 #define PARTS_PER_DISK 16
219 #define PARTS_PER_EXT_DISK 256
221 #define BLKIF_MAJOR(dev) ((dev)>>8)
222 #define BLKIF_MINOR(dev) ((dev) & 0xff)
225 #define EXTENDED (1<<EXT_SHIFT)
226 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
227 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
228 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
229 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
230 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
231 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
233 #define DEV_NAME "xvd" /* name in /dev */
236 * Grants are always the same size as a Xen page (i.e 4KB).
237 * A physical segment is always the same size as a Linux page.
238 * Number of grants per physical segment
240 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
242 #define GRANTS_PER_INDIRECT_FRAME \
243 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
245 #define PSEGS_PER_INDIRECT_FRAME \
246 (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
248 #define INDIRECT_GREFS(_grants) \
249 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
251 #define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG)
253 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
254 static void blkfront_gather_backend_features(struct blkfront_info *info);
256 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
258 unsigned long free = rinfo->shadow_free;
260 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
261 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
262 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
266 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
269 if (rinfo->shadow[id].req.u.rw.id != id)
271 if (rinfo->shadow[id].request == NULL)
273 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
274 rinfo->shadow[id].request = NULL;
275 rinfo->shadow_free = id;
279 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
281 struct blkfront_info *info = rinfo->dev_info;
282 struct page *granted_page;
283 struct grant *gnt_list_entry, *n;
287 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
291 if (info->feature_persistent) {
292 granted_page = alloc_page(GFP_NOIO);
294 kfree(gnt_list_entry);
297 gnt_list_entry->page = granted_page;
300 gnt_list_entry->gref = GRANT_INVALID_REF;
301 list_add(&gnt_list_entry->node, &rinfo->grants);
308 list_for_each_entry_safe(gnt_list_entry, n,
309 &rinfo->grants, node) {
310 list_del(&gnt_list_entry->node);
311 if (info->feature_persistent)
312 __free_page(gnt_list_entry->page);
313 kfree(gnt_list_entry);
320 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
322 struct grant *gnt_list_entry;
324 BUG_ON(list_empty(&rinfo->grants));
325 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
327 list_del(&gnt_list_entry->node);
329 if (gnt_list_entry->gref != GRANT_INVALID_REF)
330 rinfo->persistent_gnts_c--;
332 return gnt_list_entry;
335 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
336 const struct blkfront_info *info)
338 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
339 info->xbdev->otherend_id,
340 gnt_list_entry->page,
344 static struct grant *get_grant(grant_ref_t *gref_head,
346 struct blkfront_ring_info *rinfo)
348 struct grant *gnt_list_entry = get_free_grant(rinfo);
349 struct blkfront_info *info = rinfo->dev_info;
351 if (gnt_list_entry->gref != GRANT_INVALID_REF)
352 return gnt_list_entry;
354 /* Assign a gref to this page */
355 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
356 BUG_ON(gnt_list_entry->gref == -ENOSPC);
357 if (info->feature_persistent)
358 grant_foreign_access(gnt_list_entry, info);
360 /* Grant access to the GFN passed by the caller */
361 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
362 info->xbdev->otherend_id,
366 return gnt_list_entry;
369 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
370 struct blkfront_ring_info *rinfo)
372 struct grant *gnt_list_entry = get_free_grant(rinfo);
373 struct blkfront_info *info = rinfo->dev_info;
375 if (gnt_list_entry->gref != GRANT_INVALID_REF)
376 return gnt_list_entry;
378 /* Assign a gref to this page */
379 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
380 BUG_ON(gnt_list_entry->gref == -ENOSPC);
381 if (!info->feature_persistent) {
382 struct page *indirect_page;
384 /* Fetch a pre-allocated page to use for indirect grefs */
385 BUG_ON(list_empty(&rinfo->indirect_pages));
386 indirect_page = list_first_entry(&rinfo->indirect_pages,
388 list_del(&indirect_page->lru);
389 gnt_list_entry->page = indirect_page;
391 grant_foreign_access(gnt_list_entry, info);
393 return gnt_list_entry;
396 static const char *op_name(int op)
398 static const char *const names[] = {
399 [BLKIF_OP_READ] = "read",
400 [BLKIF_OP_WRITE] = "write",
401 [BLKIF_OP_WRITE_BARRIER] = "barrier",
402 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
403 [BLKIF_OP_DISCARD] = "discard" };
405 if (op < 0 || op >= ARRAY_SIZE(names))
413 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
415 unsigned int end = minor + nr;
418 if (end > nr_minors) {
419 unsigned long *bitmap, *old;
421 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
426 spin_lock(&minor_lock);
427 if (end > nr_minors) {
429 memcpy(bitmap, minors,
430 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
432 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
435 spin_unlock(&minor_lock);
439 spin_lock(&minor_lock);
440 if (find_next_bit(minors, end, minor) >= end) {
441 bitmap_set(minors, minor, nr);
445 spin_unlock(&minor_lock);
450 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
452 unsigned int end = minor + nr;
454 BUG_ON(end > nr_minors);
455 spin_lock(&minor_lock);
456 bitmap_clear(minors, minor, nr);
457 spin_unlock(&minor_lock);
460 static void blkif_restart_queue_callback(void *arg)
462 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
463 schedule_work(&rinfo->work);
466 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
468 /* We don't have real geometry info, but let's at least return
469 values consistent with the size of the device */
470 sector_t nsect = get_capacity(bd->bd_disk);
471 sector_t cylinders = nsect;
475 sector_div(cylinders, hg->heads * hg->sectors);
476 hg->cylinders = cylinders;
477 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
478 hg->cylinders = 0xffff;
482 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
483 unsigned command, unsigned long argument)
485 struct blkfront_info *info = bdev->bd_disk->private_data;
488 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
489 command, (long)argument);
492 case CDROMMULTISESSION:
493 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
494 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
495 if (put_user(0, (char __user *)(argument + i)))
499 case CDROM_GET_CAPABILITY: {
500 struct gendisk *gd = info->gd;
501 if (gd->flags & GENHD_FL_CD)
507 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
509 return -EINVAL; /* same return as native Linux */
515 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
517 struct blkif_request **ring_req)
521 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
522 rinfo->ring.req_prod_pvt++;
524 id = get_id_from_freelist(rinfo);
525 rinfo->shadow[id].request = req;
526 rinfo->shadow[id].status = REQ_WAITING;
527 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
529 (*ring_req)->u.rw.id = id;
534 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
536 struct blkfront_info *info = rinfo->dev_info;
537 struct blkif_request *ring_req;
540 /* Fill out a communications ring structure. */
541 id = blkif_ring_get_request(rinfo, req, &ring_req);
543 ring_req->operation = BLKIF_OP_DISCARD;
544 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
545 ring_req->u.discard.id = id;
546 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
547 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
548 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
550 ring_req->u.discard.flag = 0;
552 /* Keep a private copy so we can reissue requests when recovering. */
553 rinfo->shadow[id].req = *ring_req;
558 struct setup_rw_req {
559 unsigned int grant_idx;
560 struct blkif_request_segment *segments;
561 struct blkfront_ring_info *rinfo;
562 struct blkif_request *ring_req;
563 grant_ref_t gref_head;
565 /* Only used when persistent grant is used and it's a read request */
567 unsigned int bvec_off;
570 bool require_extra_req;
571 struct blkif_request *extra_ring_req;
574 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
575 unsigned int len, void *data)
577 struct setup_rw_req *setup = data;
579 struct grant *gnt_list_entry;
580 unsigned int fsect, lsect;
581 /* Convenient aliases */
582 unsigned int grant_idx = setup->grant_idx;
583 struct blkif_request *ring_req = setup->ring_req;
584 struct blkfront_ring_info *rinfo = setup->rinfo;
586 * We always use the shadow of the first request to store the list
587 * of grant associated to the block I/O request. This made the
588 * completion more easy to handle even if the block I/O request is
591 struct blk_shadow *shadow = &rinfo->shadow[setup->id];
593 if (unlikely(setup->require_extra_req &&
594 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
596 * We are using the second request, setup grant_idx
597 * to be the index of the segment array.
599 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
600 ring_req = setup->extra_ring_req;
603 if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
604 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
606 kunmap_atomic(setup->segments);
608 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
609 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
610 shadow->indirect_grants[n] = gnt_list_entry;
611 setup->segments = kmap_atomic(gnt_list_entry->page);
612 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
615 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
616 ref = gnt_list_entry->gref;
618 * All the grants are stored in the shadow of the first
619 * request. Therefore we have to use the global index.
621 shadow->grants_used[setup->grant_idx] = gnt_list_entry;
623 if (setup->need_copy) {
626 shared_data = kmap_atomic(gnt_list_entry->page);
628 * this does not wipe data stored outside the
629 * range sg->offset..sg->offset+sg->length.
630 * Therefore, blkback *could* see data from
631 * previous requests. This is OK as long as
632 * persistent grants are shared with just one
633 * domain. It may need refactoring if this
636 memcpy(shared_data + offset,
637 setup->bvec_data + setup->bvec_off,
640 kunmap_atomic(shared_data);
641 setup->bvec_off += len;
645 lsect = fsect + (len >> 9) - 1;
646 if (ring_req->operation != BLKIF_OP_INDIRECT) {
647 ring_req->u.rw.seg[grant_idx] =
648 (struct blkif_request_segment) {
651 .last_sect = lsect };
653 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
654 (struct blkif_request_segment) {
657 .last_sect = lsect };
660 (setup->grant_idx)++;
663 static void blkif_setup_extra_req(struct blkif_request *first,
664 struct blkif_request *second)
666 uint16_t nr_segments = first->u.rw.nr_segments;
669 * The second request is only present when the first request uses
670 * all its segments. It's always the continuity of the first one.
672 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
674 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
675 second->u.rw.sector_number = first->u.rw.sector_number +
676 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
678 second->u.rw.handle = first->u.rw.handle;
679 second->operation = first->operation;
682 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
684 struct blkfront_info *info = rinfo->dev_info;
685 struct blkif_request *ring_req, *extra_ring_req = NULL;
686 unsigned long id, extra_id = NO_ASSOCIATED_ID;
687 bool require_extra_req = false;
689 struct setup_rw_req setup = {
693 .need_copy = rq_data_dir(req) && info->feature_persistent,
697 * Used to store if we are able to queue the request by just using
698 * existing persistent grants, or if we have to get new grants,
699 * as there are not sufficiently many free.
701 struct scatterlist *sg;
702 int num_sg, max_grefs, num_grant;
704 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
705 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
707 * If we are using indirect segments we need to account
708 * for the indirect grefs used in the request.
710 max_grefs += INDIRECT_GREFS(max_grefs);
713 * We have to reserve 'max_grefs' grants because persistent
714 * grants are shared by all rings.
717 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) {
718 gnttab_request_free_callback(
720 blkif_restart_queue_callback,
726 /* Fill out a communications ring structure. */
727 id = blkif_ring_get_request(rinfo, req, &ring_req);
729 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
731 /* Calculate the number of grant used */
732 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
733 num_grant += gnttab_count_grant(sg->offset, sg->length);
735 require_extra_req = info->max_indirect_segments == 0 &&
736 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
737 BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
739 rinfo->shadow[id].num_sg = num_sg;
740 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
741 likely(!require_extra_req)) {
743 * The indirect operation can only be a BLKIF_OP_READ or
746 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
747 ring_req->operation = BLKIF_OP_INDIRECT;
748 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
749 BLKIF_OP_WRITE : BLKIF_OP_READ;
750 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
751 ring_req->u.indirect.handle = info->handle;
752 ring_req->u.indirect.nr_segments = num_grant;
754 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
755 ring_req->u.rw.handle = info->handle;
756 ring_req->operation = rq_data_dir(req) ?
757 BLKIF_OP_WRITE : BLKIF_OP_READ;
758 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
760 * Ideally we can do an unordered flush-to-disk.
761 * In case the backend onlysupports barriers, use that.
762 * A barrier request a superset of FUA, so we can
763 * implement it the same way. (It's also a FLUSH+FUA,
764 * since it is guaranteed ordered WRT previous writes.)
766 switch (info->feature_flush &
767 ((REQ_FLUSH|REQ_FUA))) {
768 case REQ_FLUSH|REQ_FUA:
769 ring_req->operation =
770 BLKIF_OP_WRITE_BARRIER;
773 ring_req->operation =
774 BLKIF_OP_FLUSH_DISKCACHE;
777 ring_req->operation = 0;
780 ring_req->u.rw.nr_segments = num_grant;
781 if (unlikely(require_extra_req)) {
782 extra_id = blkif_ring_get_request(rinfo, req,
785 * Only the first request contains the scatter-gather
788 rinfo->shadow[extra_id].num_sg = 0;
790 blkif_setup_extra_req(ring_req, extra_ring_req);
792 /* Link the 2 requests together */
793 rinfo->shadow[extra_id].associated_id = id;
794 rinfo->shadow[id].associated_id = extra_id;
798 setup.ring_req = ring_req;
801 setup.require_extra_req = require_extra_req;
802 if (unlikely(require_extra_req))
803 setup.extra_ring_req = extra_ring_req;
805 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
806 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
808 if (setup.need_copy) {
809 setup.bvec_off = sg->offset;
810 setup.bvec_data = kmap_atomic(sg_page(sg));
813 gnttab_foreach_grant_in_range(sg_page(sg),
816 blkif_setup_rw_req_grant,
820 kunmap_atomic(setup.bvec_data);
823 kunmap_atomic(setup.segments);
825 /* Keep a private copy so we can reissue requests when recovering. */
826 rinfo->shadow[id].req = *ring_req;
827 if (unlikely(require_extra_req))
828 rinfo->shadow[extra_id].req = *extra_ring_req;
831 gnttab_free_grant_references(setup.gref_head);
837 * Generate a Xen blkfront IO request from a blk layer request. Reads
838 * and writes are handled as expected.
840 * @req: a request struct
842 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
844 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
847 if (unlikely(req->cmd_flags & (REQ_DISCARD | 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->cmd_flags & REQ_FLUSH) &&
868 !(info->feature_flush & REQ_FLUSH)) ||
869 ((req->cmd_flags & REQ_FUA) &&
870 !(info->feature_flush & REQ_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(unsigned int feature_flush)
983 switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) {
984 case REQ_FLUSH|REQ_FUA:
985 return "barrier: enabled;";
987 return "flush diskcache: enabled;";
989 return "barrier or flush: disabled;";
993 static void xlvbd_flush(struct blkfront_info *info)
995 blk_queue_write_cache(info->rq, info->feature_flush & REQ_FLUSH,
996 info->feature_flush & REQ_FUA);
997 pr_info("blkfront: %s: %s %s %s %s %s\n",
998 info->gd->disk_name, flush_info(info->feature_flush),
999 "persistent grants:", info->feature_persistent ?
1000 "enabled;" : "disabled;", "indirect descriptors:",
1001 info->max_indirect_segments ? "enabled;" : "disabled;");
1004 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1007 major = BLKIF_MAJOR(vdevice);
1008 *minor = BLKIF_MINOR(vdevice);
1010 case XEN_IDE0_MAJOR:
1011 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1012 *minor = ((*minor / 64) * PARTS_PER_DISK) +
1013 EMULATED_HD_DISK_MINOR_OFFSET;
1015 case XEN_IDE1_MAJOR:
1016 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1017 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1018 EMULATED_HD_DISK_MINOR_OFFSET;
1020 case XEN_SCSI_DISK0_MAJOR:
1021 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1022 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1024 case XEN_SCSI_DISK1_MAJOR:
1025 case XEN_SCSI_DISK2_MAJOR:
1026 case XEN_SCSI_DISK3_MAJOR:
1027 case XEN_SCSI_DISK4_MAJOR:
1028 case XEN_SCSI_DISK5_MAJOR:
1029 case XEN_SCSI_DISK6_MAJOR:
1030 case XEN_SCSI_DISK7_MAJOR:
1031 *offset = (*minor / PARTS_PER_DISK) +
1032 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1033 EMULATED_SD_DISK_NAME_OFFSET;
1035 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1036 EMULATED_SD_DISK_MINOR_OFFSET;
1038 case XEN_SCSI_DISK8_MAJOR:
1039 case XEN_SCSI_DISK9_MAJOR:
1040 case XEN_SCSI_DISK10_MAJOR:
1041 case XEN_SCSI_DISK11_MAJOR:
1042 case XEN_SCSI_DISK12_MAJOR:
1043 case XEN_SCSI_DISK13_MAJOR:
1044 case XEN_SCSI_DISK14_MAJOR:
1045 case XEN_SCSI_DISK15_MAJOR:
1046 *offset = (*minor / PARTS_PER_DISK) +
1047 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1048 EMULATED_SD_DISK_NAME_OFFSET;
1050 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1051 EMULATED_SD_DISK_MINOR_OFFSET;
1054 *offset = *minor / PARTS_PER_DISK;
1057 printk(KERN_WARNING "blkfront: your disk configuration is "
1058 "incorrect, please use an xvd device instead\n");
1064 static char *encode_disk_name(char *ptr, unsigned int n)
1067 ptr = encode_disk_name(ptr, n / 26 - 1);
1068 *ptr = 'a' + n % 26;
1072 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1073 struct blkfront_info *info,
1074 u16 vdisk_info, u16 sector_size,
1075 unsigned int physical_sector_size)
1080 unsigned int offset;
1085 BUG_ON(info->gd != NULL);
1086 BUG_ON(info->rq != NULL);
1088 if ((info->vdevice>>EXT_SHIFT) > 1) {
1089 /* this is above the extended range; something is wrong */
1090 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1094 if (!VDEV_IS_EXTENDED(info->vdevice)) {
1095 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1098 nr_parts = PARTS_PER_DISK;
1100 minor = BLKIF_MINOR_EXT(info->vdevice);
1101 nr_parts = PARTS_PER_EXT_DISK;
1102 offset = minor / nr_parts;
1103 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1104 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1105 "emulated IDE disks,\n\t choose an xvd device name"
1106 "from xvde on\n", info->vdevice);
1108 if (minor >> MINORBITS) {
1109 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1110 info->vdevice, minor);
1114 if ((minor % nr_parts) == 0)
1115 nr_minors = nr_parts;
1117 err = xlbd_reserve_minors(minor, nr_minors);
1122 gd = alloc_disk(nr_minors);
1126 strcpy(gd->disk_name, DEV_NAME);
1127 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1128 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1132 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1133 "%d", minor & (nr_parts - 1));
1135 gd->major = XENVBD_MAJOR;
1136 gd->first_minor = minor;
1137 gd->fops = &xlvbd_block_fops;
1138 gd->private_data = info;
1139 gd->driverfs_dev = &(info->xbdev->dev);
1140 set_capacity(gd, capacity);
1142 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
1143 info->max_indirect_segments ? :
1144 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
1149 info->rq = gd->queue;
1154 if (vdisk_info & VDISK_READONLY)
1157 if (vdisk_info & VDISK_REMOVABLE)
1158 gd->flags |= GENHD_FL_REMOVABLE;
1160 if (vdisk_info & VDISK_CDROM)
1161 gd->flags |= GENHD_FL_CD;
1166 xlbd_release_minors(minor, nr_minors);
1171 static void xlvbd_release_gendisk(struct blkfront_info *info)
1173 unsigned int minor, nr_minors, i;
1175 if (info->rq == NULL)
1178 /* No more blkif_request(). */
1179 blk_mq_stop_hw_queues(info->rq);
1181 for (i = 0; i < info->nr_rings; i++) {
1182 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1184 /* No more gnttab callback work. */
1185 gnttab_cancel_free_callback(&rinfo->callback);
1187 /* Flush gnttab callback work. Must be done with no locks held. */
1188 flush_work(&rinfo->work);
1191 del_gendisk(info->gd);
1193 minor = info->gd->first_minor;
1194 nr_minors = info->gd->minors;
1195 xlbd_release_minors(minor, nr_minors);
1197 blk_cleanup_queue(info->rq);
1198 blk_mq_free_tag_set(&info->tag_set);
1205 /* Already hold rinfo->ring_lock. */
1206 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1208 if (!RING_FULL(&rinfo->ring))
1209 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1212 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1214 unsigned long flags;
1216 spin_lock_irqsave(&rinfo->ring_lock, flags);
1217 kick_pending_request_queues_locked(rinfo);
1218 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1221 static void blkif_restart_queue(struct work_struct *work)
1223 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1225 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1226 kick_pending_request_queues(rinfo);
1229 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1231 struct grant *persistent_gnt, *n;
1232 struct blkfront_info *info = rinfo->dev_info;
1236 * Remove indirect pages, this only happens when using indirect
1237 * descriptors but not persistent grants
1239 if (!list_empty(&rinfo->indirect_pages)) {
1240 struct page *indirect_page, *n;
1242 BUG_ON(info->feature_persistent);
1243 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1244 list_del(&indirect_page->lru);
1245 __free_page(indirect_page);
1249 /* Remove all persistent grants. */
1250 if (!list_empty(&rinfo->grants)) {
1251 list_for_each_entry_safe(persistent_gnt, n,
1252 &rinfo->grants, node) {
1253 list_del(&persistent_gnt->node);
1254 if (persistent_gnt->gref != GRANT_INVALID_REF) {
1255 gnttab_end_foreign_access(persistent_gnt->gref,
1257 rinfo->persistent_gnts_c--;
1259 if (info->feature_persistent)
1260 __free_page(persistent_gnt->page);
1261 kfree(persistent_gnt);
1264 BUG_ON(rinfo->persistent_gnts_c != 0);
1266 for (i = 0; i < BLK_RING_SIZE(info); i++) {
1268 * Clear persistent grants present in requests already
1269 * on the shared ring
1271 if (!rinfo->shadow[i].request)
1274 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1275 rinfo->shadow[i].req.u.indirect.nr_segments :
1276 rinfo->shadow[i].req.u.rw.nr_segments;
1277 for (j = 0; j < segs; j++) {
1278 persistent_gnt = rinfo->shadow[i].grants_used[j];
1279 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1280 if (info->feature_persistent)
1281 __free_page(persistent_gnt->page);
1282 kfree(persistent_gnt);
1285 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1287 * If this is not an indirect operation don't try to
1288 * free indirect segments
1292 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1293 persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1294 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1295 __free_page(persistent_gnt->page);
1296 kfree(persistent_gnt);
1300 kfree(rinfo->shadow[i].grants_used);
1301 rinfo->shadow[i].grants_used = NULL;
1302 kfree(rinfo->shadow[i].indirect_grants);
1303 rinfo->shadow[i].indirect_grants = NULL;
1304 kfree(rinfo->shadow[i].sg);
1305 rinfo->shadow[i].sg = NULL;
1308 /* No more gnttab callback work. */
1309 gnttab_cancel_free_callback(&rinfo->callback);
1311 /* Flush gnttab callback work. Must be done with no locks held. */
1312 flush_work(&rinfo->work);
1314 /* Free resources associated with old device channel. */
1315 for (i = 0; i < info->nr_ring_pages; i++) {
1316 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1317 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1318 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1321 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE));
1322 rinfo->ring.sring = NULL;
1325 unbind_from_irqhandler(rinfo->irq, rinfo);
1326 rinfo->evtchn = rinfo->irq = 0;
1329 static void blkif_free(struct blkfront_info *info, int suspend)
1333 /* Prevent new requests being issued until we fix things up. */
1334 info->connected = suspend ?
1335 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1336 /* No more blkif_request(). */
1338 blk_mq_stop_hw_queues(info->rq);
1340 for (i = 0; i < info->nr_rings; i++)
1341 blkif_free_ring(&info->rinfo[i]);
1348 struct copy_from_grant {
1349 const struct blk_shadow *s;
1350 unsigned int grant_idx;
1351 unsigned int bvec_offset;
1355 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1356 unsigned int len, void *data)
1358 struct copy_from_grant *info = data;
1360 /* Convenient aliases */
1361 const struct blk_shadow *s = info->s;
1363 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1365 memcpy(info->bvec_data + info->bvec_offset,
1366 shared_data + offset, len);
1368 info->bvec_offset += len;
1371 kunmap_atomic(shared_data);
1374 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1378 case BLKIF_RSP_OKAY:
1380 case BLKIF_RSP_EOPNOTSUPP:
1381 return REQ_EOPNOTSUPP;
1382 case BLKIF_RSP_ERROR:
1390 * Get the final status of the block request based on two ring response
1392 static int blkif_get_final_status(enum blk_req_status s1,
1393 enum blk_req_status s2)
1395 BUG_ON(s1 == REQ_WAITING);
1396 BUG_ON(s2 == REQ_WAITING);
1398 if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1399 return BLKIF_RSP_ERROR;
1400 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1401 return BLKIF_RSP_EOPNOTSUPP;
1402 return BLKIF_RSP_OKAY;
1405 static bool blkif_completion(unsigned long *id,
1406 struct blkfront_ring_info *rinfo,
1407 struct blkif_response *bret)
1410 struct scatterlist *sg;
1411 int num_sg, num_grant;
1412 struct blkfront_info *info = rinfo->dev_info;
1413 struct blk_shadow *s = &rinfo->shadow[*id];
1414 struct copy_from_grant data = {
1418 num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1419 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1421 /* The I/O request may be split in two. */
1422 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1423 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1425 /* Keep the status of the current response in shadow. */
1426 s->status = blkif_rsp_to_req_status(bret->status);
1428 /* Wait the second response if not yet here. */
1429 if (s2->status == REQ_WAITING)
1432 bret->status = blkif_get_final_status(s->status,
1436 * All the grants is stored in the first shadow in order
1437 * to make the completion code simpler.
1439 num_grant += s2->req.u.rw.nr_segments;
1442 * The two responses may not come in order. Only the
1443 * first request will store the scatter-gather list.
1445 if (s2->num_sg != 0) {
1446 /* Update "id" with the ID of the first response. */
1447 *id = s->associated_id;
1452 * We don't need anymore the second request, so recycling
1455 if (add_id_to_freelist(rinfo, s->associated_id))
1456 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1457 info->gd->disk_name, s->associated_id);
1463 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1464 for_each_sg(s->sg, sg, num_sg, i) {
1465 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1467 data.bvec_offset = sg->offset;
1468 data.bvec_data = kmap_atomic(sg_page(sg));
1470 gnttab_foreach_grant_in_range(sg_page(sg),
1473 blkif_copy_from_grant,
1476 kunmap_atomic(data.bvec_data);
1479 /* Add the persistent grant into the list of free grants */
1480 for (i = 0; i < num_grant; i++) {
1481 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1483 * If the grant is still mapped by the backend (the
1484 * backend has chosen to make this grant persistent)
1485 * we add it at the head of the list, so it will be
1488 if (!info->feature_persistent)
1489 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1490 s->grants_used[i]->gref);
1491 list_add(&s->grants_used[i]->node, &rinfo->grants);
1492 rinfo->persistent_gnts_c++;
1495 * If the grant is not mapped by the backend we end the
1496 * foreign access and add it to the tail of the list,
1497 * so it will not be picked again unless we run out of
1498 * persistent grants.
1500 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1501 s->grants_used[i]->gref = GRANT_INVALID_REF;
1502 list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1505 if (s->req.operation == BLKIF_OP_INDIRECT) {
1506 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1507 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1508 if (!info->feature_persistent)
1509 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1510 s->indirect_grants[i]->gref);
1511 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1512 rinfo->persistent_gnts_c++;
1514 struct page *indirect_page;
1516 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1518 * Add the used indirect page back to the list of
1519 * available pages for indirect grefs.
1521 if (!info->feature_persistent) {
1522 indirect_page = s->indirect_grants[i]->page;
1523 list_add(&indirect_page->lru, &rinfo->indirect_pages);
1525 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1526 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1534 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1536 struct request *req;
1537 struct blkif_response *bret;
1539 unsigned long flags;
1540 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1541 struct blkfront_info *info = rinfo->dev_info;
1544 if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1547 spin_lock_irqsave(&rinfo->ring_lock, flags);
1549 rp = rinfo->ring.sring->rsp_prod;
1550 rmb(); /* Ensure we see queued responses up to 'rp'. */
1552 for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1555 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1558 * The backend has messed up and given us an id that we would
1559 * never have given to it (we stamp it up to BLK_RING_SIZE -
1560 * look in get_id_from_freelist.
1562 if (id >= BLK_RING_SIZE(info)) {
1563 WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1564 info->gd->disk_name, op_name(bret->operation), id);
1565 /* We can't safely get the 'struct request' as
1566 * the id is busted. */
1569 req = rinfo->shadow[id].request;
1571 if (bret->operation != BLKIF_OP_DISCARD) {
1573 * We may need to wait for an extra response if the
1574 * I/O request is split in 2
1576 if (!blkif_completion(&id, rinfo, bret))
1580 if (add_id_to_freelist(rinfo, id)) {
1581 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1582 info->gd->disk_name, op_name(bret->operation), id);
1586 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1587 switch (bret->operation) {
1588 case BLKIF_OP_DISCARD:
1589 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1590 struct request_queue *rq = info->rq;
1591 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1592 info->gd->disk_name, op_name(bret->operation));
1593 error = -EOPNOTSUPP;
1594 info->feature_discard = 0;
1595 info->feature_secdiscard = 0;
1596 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1597 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1599 blk_mq_complete_request(req, error);
1601 case BLKIF_OP_FLUSH_DISKCACHE:
1602 case BLKIF_OP_WRITE_BARRIER:
1603 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1604 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1605 info->gd->disk_name, op_name(bret->operation));
1606 error = -EOPNOTSUPP;
1608 if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1609 rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1610 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1611 info->gd->disk_name, op_name(bret->operation));
1612 error = -EOPNOTSUPP;
1614 if (unlikely(error)) {
1615 if (error == -EOPNOTSUPP)
1617 info->feature_flush = 0;
1622 case BLKIF_OP_WRITE:
1623 if (unlikely(bret->status != BLKIF_RSP_OKAY))
1624 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1625 "request: %x\n", bret->status);
1627 blk_mq_complete_request(req, error);
1634 rinfo->ring.rsp_cons = i;
1636 if (i != rinfo->ring.req_prod_pvt) {
1638 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1642 rinfo->ring.sring->rsp_event = i + 1;
1644 kick_pending_request_queues_locked(rinfo);
1646 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1652 static int setup_blkring(struct xenbus_device *dev,
1653 struct blkfront_ring_info *rinfo)
1655 struct blkif_sring *sring;
1657 struct blkfront_info *info = rinfo->dev_info;
1658 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1659 grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1661 for (i = 0; i < info->nr_ring_pages; i++)
1662 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1664 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1665 get_order(ring_size));
1667 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1670 SHARED_RING_INIT(sring);
1671 FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1673 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1675 free_pages((unsigned long)sring, get_order(ring_size));
1676 rinfo->ring.sring = NULL;
1679 for (i = 0; i < info->nr_ring_pages; i++)
1680 rinfo->ring_ref[i] = gref[i];
1682 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1686 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1689 xenbus_dev_fatal(dev, err,
1690 "bind_evtchn_to_irqhandler failed");
1697 blkif_free(info, 0);
1702 * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1703 * ring buffer may have multi pages depending on ->nr_ring_pages.
1705 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1706 struct blkfront_ring_info *rinfo, const char *dir)
1710 const char *message = NULL;
1711 struct blkfront_info *info = rinfo->dev_info;
1713 if (info->nr_ring_pages == 1) {
1714 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1716 message = "writing ring-ref";
1717 goto abort_transaction;
1720 for (i = 0; i < info->nr_ring_pages; i++) {
1721 char ring_ref_name[RINGREF_NAME_LEN];
1723 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1724 err = xenbus_printf(xbt, dir, ring_ref_name,
1725 "%u", rinfo->ring_ref[i]);
1727 message = "writing ring-ref";
1728 goto abort_transaction;
1733 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1735 message = "writing event-channel";
1736 goto abort_transaction;
1742 xenbus_transaction_end(xbt, 1);
1744 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1749 /* Common code used when first setting up, and when resuming. */
1750 static int talk_to_blkback(struct xenbus_device *dev,
1751 struct blkfront_info *info)
1753 const char *message = NULL;
1754 struct xenbus_transaction xbt;
1756 unsigned int i, max_page_order = 0;
1757 unsigned int ring_page_order = 0;
1759 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1760 "max-ring-page-order", "%u", &max_page_order);
1762 info->nr_ring_pages = 1;
1764 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1765 info->nr_ring_pages = 1 << ring_page_order;
1768 for (i = 0; i < info->nr_rings; i++) {
1769 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1771 /* Create shared ring, alloc event channel. */
1772 err = setup_blkring(dev, rinfo);
1774 goto destroy_blkring;
1778 err = xenbus_transaction_start(&xbt);
1780 xenbus_dev_fatal(dev, err, "starting transaction");
1781 goto destroy_blkring;
1784 if (info->nr_ring_pages > 1) {
1785 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1788 message = "writing ring-page-order";
1789 goto abort_transaction;
1793 /* We already got the number of queues/rings in _probe */
1794 if (info->nr_rings == 1) {
1795 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1797 goto destroy_blkring;
1802 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1805 message = "writing multi-queue-num-queues";
1806 goto abort_transaction;
1809 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1810 path = kmalloc(pathsize, GFP_KERNEL);
1813 message = "ENOMEM while writing ring references";
1814 goto abort_transaction;
1817 for (i = 0; i < info->nr_rings; i++) {
1818 memset(path, 0, pathsize);
1819 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1820 err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1823 goto destroy_blkring;
1828 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1829 XEN_IO_PROTO_ABI_NATIVE);
1831 message = "writing protocol";
1832 goto abort_transaction;
1834 err = xenbus_printf(xbt, dev->nodename,
1835 "feature-persistent", "%u", 1);
1838 "writing persistent grants feature to xenbus");
1840 err = xenbus_transaction_end(xbt, 0);
1844 xenbus_dev_fatal(dev, err, "completing transaction");
1845 goto destroy_blkring;
1848 for (i = 0; i < info->nr_rings; i++) {
1850 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1852 for (j = 0; j < BLK_RING_SIZE(info); j++)
1853 rinfo->shadow[j].req.u.rw.id = j + 1;
1854 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1856 xenbus_switch_state(dev, XenbusStateInitialised);
1861 xenbus_transaction_end(xbt, 1);
1863 xenbus_dev_fatal(dev, err, "%s", message);
1865 blkif_free(info, 0);
1868 dev_set_drvdata(&dev->dev, NULL);
1873 static int negotiate_mq(struct blkfront_info *info)
1875 unsigned int backend_max_queues = 0;
1879 BUG_ON(info->nr_rings);
1881 /* Check if backend supports multiple queues. */
1882 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1883 "multi-queue-max-queues", "%u", &backend_max_queues);
1885 backend_max_queues = 1;
1887 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1888 /* We need at least one ring. */
1889 if (!info->nr_rings)
1892 info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
1894 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1898 for (i = 0; i < info->nr_rings; i++) {
1899 struct blkfront_ring_info *rinfo;
1901 rinfo = &info->rinfo[i];
1902 INIT_LIST_HEAD(&rinfo->indirect_pages);
1903 INIT_LIST_HEAD(&rinfo->grants);
1904 rinfo->dev_info = info;
1905 INIT_WORK(&rinfo->work, blkif_restart_queue);
1906 spin_lock_init(&rinfo->ring_lock);
1911 * Entry point to this code when a new device is created. Allocate the basic
1912 * structures and the ring buffer for communication with the backend, and
1913 * inform the backend of the appropriate details for those. Switch to
1914 * Initialised state.
1916 static int blkfront_probe(struct xenbus_device *dev,
1917 const struct xenbus_device_id *id)
1920 struct blkfront_info *info;
1922 /* FIXME: Use dynamic device id if this is not set. */
1923 err = xenbus_scanf(XBT_NIL, dev->nodename,
1924 "virtual-device", "%i", &vdevice);
1926 /* go looking in the extended area instead */
1927 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1930 xenbus_dev_fatal(dev, err, "reading virtual-device");
1935 if (xen_hvm_domain()) {
1938 /* no unplug has been done: do not hook devices != xen vbds */
1939 if (xen_has_pv_and_legacy_disk_devices()) {
1942 if (!VDEV_IS_EXTENDED(vdevice))
1943 major = BLKIF_MAJOR(vdevice);
1945 major = XENVBD_MAJOR;
1947 if (major != XENVBD_MAJOR) {
1949 "%s: HVM does not support vbd %d as xen block device\n",
1954 /* do not create a PV cdrom device if we are an HVM guest */
1955 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1958 if (strncmp(type, "cdrom", 5) == 0) {
1964 info = kzalloc(sizeof(*info), GFP_KERNEL);
1966 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1971 err = negotiate_mq(info);
1977 mutex_init(&info->mutex);
1978 info->vdevice = vdevice;
1979 info->connected = BLKIF_STATE_DISCONNECTED;
1981 /* Front end dir is a number, which is used as the id. */
1982 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1983 dev_set_drvdata(&dev->dev, info);
1988 static void split_bio_end(struct bio *bio)
1990 struct split_bio *split_bio = bio->bi_private;
1992 if (atomic_dec_and_test(&split_bio->pending)) {
1993 split_bio->bio->bi_phys_segments = 0;
1994 split_bio->bio->bi_error = bio->bi_error;
1995 bio_endio(split_bio->bio);
2001 static int blkif_recover(struct blkfront_info *info)
2003 unsigned int i, r_index;
2004 struct request *req, *n;
2005 struct blk_shadow *copy;
2007 struct bio *bio, *cloned_bio;
2008 struct bio_list bio_list, merge_bio;
2009 unsigned int segs, offset;
2011 struct split_bio *split_bio;
2012 struct list_head requests;
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);
2017 bio_list_init(&bio_list);
2018 INIT_LIST_HEAD(&requests);
2020 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2021 struct blkfront_ring_info *rinfo;
2023 rinfo = &info->rinfo[r_index];
2024 /* Stage 1: Make a safe copy of the shadow state. */
2025 copy = kmemdup(rinfo->shadow, sizeof(rinfo->shadow),
2026 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
2030 /* Stage 2: Set up free list. */
2031 memset(&rinfo->shadow, 0, sizeof(rinfo->shadow));
2032 for (i = 0; i < BLK_RING_SIZE(info); i++)
2033 rinfo->shadow[i].req.u.rw.id = i+1;
2034 rinfo->shadow_free = rinfo->ring.req_prod_pvt;
2035 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
2037 rc = blkfront_setup_indirect(rinfo);
2043 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2045 if (!copy[i].request)
2049 * Get the bios in the request so we can re-queue them.
2051 if (copy[i].request->cmd_flags &
2052 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
2054 * Flush operations don't contain bios, so
2055 * we need to requeue the whole request
2057 list_add(©[i].request->queuelist, &requests);
2060 merge_bio.head = copy[i].request->bio;
2061 merge_bio.tail = copy[i].request->biotail;
2062 bio_list_merge(&bio_list, &merge_bio);
2063 copy[i].request->bio = NULL;
2064 blk_end_request_all(copy[i].request, 0);
2069 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2071 /* Now safe for us to use the shared ring */
2072 info->connected = BLKIF_STATE_CONNECTED;
2074 for (r_index = 0; r_index < info->nr_rings; r_index++) {
2075 struct blkfront_ring_info *rinfo;
2077 rinfo = &info->rinfo[r_index];
2078 /* Kick any other new requests queued since we resumed */
2079 kick_pending_request_queues(rinfo);
2082 list_for_each_entry_safe(req, n, &requests, queuelist) {
2083 /* Requeue pending requests (flush or discard) */
2084 list_del_init(&req->queuelist);
2085 BUG_ON(req->nr_phys_segments > segs);
2086 blk_mq_requeue_request(req);
2088 blk_mq_kick_requeue_list(info->rq);
2090 while ((bio = bio_list_pop(&bio_list)) != NULL) {
2091 /* Traverse the list of pending bios and re-queue them */
2092 if (bio_segments(bio) > segs) {
2094 * This bio has more segments than what we can
2095 * handle, we have to split it.
2097 pending = (bio_segments(bio) + segs - 1) / segs;
2098 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
2099 BUG_ON(split_bio == NULL);
2100 atomic_set(&split_bio->pending, pending);
2101 split_bio->bio = bio;
2102 for (i = 0; i < pending; i++) {
2103 offset = (i * segs * XEN_PAGE_SIZE) >> 9;
2104 size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9,
2105 (unsigned int)bio_sectors(bio) - offset);
2106 cloned_bio = bio_clone(bio, GFP_NOIO);
2107 BUG_ON(cloned_bio == NULL);
2108 bio_trim(cloned_bio, offset, size);
2109 cloned_bio->bi_private = split_bio;
2110 cloned_bio->bi_end_io = split_bio_end;
2111 submit_bio(cloned_bio->bi_rw, cloned_bio);
2114 * Now we have to wait for all those smaller bios to
2115 * end, so we can also end the "parent" bio.
2119 /* We don't need to split this bio */
2120 submit_bio(bio->bi_rw, bio);
2127 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2128 * driver restart. We tear down our blkif structure and recreate it, but
2129 * leave the device-layer structures intact so that this is transparent to the
2130 * rest of the kernel.
2132 static int blkfront_resume(struct xenbus_device *dev)
2134 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2137 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2139 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2141 err = negotiate_mq(info);
2145 err = talk_to_blkback(dev, info);
2147 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2150 * We have to wait for the backend to switch to
2151 * connected state, since we want to read which
2152 * features it supports.
2158 static void blkfront_closing(struct blkfront_info *info)
2160 struct xenbus_device *xbdev = info->xbdev;
2161 struct block_device *bdev = NULL;
2163 mutex_lock(&info->mutex);
2165 if (xbdev->state == XenbusStateClosing) {
2166 mutex_unlock(&info->mutex);
2171 bdev = bdget_disk(info->gd, 0);
2173 mutex_unlock(&info->mutex);
2176 xenbus_frontend_closed(xbdev);
2180 mutex_lock(&bdev->bd_mutex);
2182 if (bdev->bd_openers) {
2183 xenbus_dev_error(xbdev, -EBUSY,
2184 "Device in use; refusing to close");
2185 xenbus_switch_state(xbdev, XenbusStateClosing);
2187 xlvbd_release_gendisk(info);
2188 xenbus_frontend_closed(xbdev);
2191 mutex_unlock(&bdev->bd_mutex);
2195 static void blkfront_setup_discard(struct blkfront_info *info)
2198 unsigned int discard_granularity;
2199 unsigned int discard_alignment;
2200 unsigned int discard_secure;
2202 info->feature_discard = 1;
2203 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2204 "discard-granularity", "%u", &discard_granularity,
2205 "discard-alignment", "%u", &discard_alignment,
2208 info->discard_granularity = discard_granularity;
2209 info->discard_alignment = discard_alignment;
2211 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2212 "discard-secure", "%d", &discard_secure,
2215 info->feature_secdiscard = !!discard_secure;
2218 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2220 unsigned int psegs, grants;
2222 struct blkfront_info *info = rinfo->dev_info;
2224 if (info->max_indirect_segments == 0) {
2226 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2229 * When an extra req is required, the maximum
2230 * grants supported is related to the size of the
2231 * Linux block segment.
2233 grants = GRANTS_PER_PSEG;
2237 grants = info->max_indirect_segments;
2238 psegs = grants / GRANTS_PER_PSEG;
2240 err = fill_grant_buffer(rinfo,
2241 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2245 if (!info->feature_persistent && info->max_indirect_segments) {
2247 * We are using indirect descriptors but not persistent
2248 * grants, we need to allocate a set of pages that can be
2249 * used for mapping indirect grefs
2251 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2253 BUG_ON(!list_empty(&rinfo->indirect_pages));
2254 for (i = 0; i < num; i++) {
2255 struct page *indirect_page = alloc_page(GFP_NOIO);
2258 list_add(&indirect_page->lru, &rinfo->indirect_pages);
2262 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2263 rinfo->shadow[i].grants_used = kzalloc(
2264 sizeof(rinfo->shadow[i].grants_used[0]) * grants,
2266 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO);
2267 if (info->max_indirect_segments)
2268 rinfo->shadow[i].indirect_grants = kzalloc(
2269 sizeof(rinfo->shadow[i].indirect_grants[0]) *
2270 INDIRECT_GREFS(grants),
2272 if ((rinfo->shadow[i].grants_used == NULL) ||
2273 (rinfo->shadow[i].sg == NULL) ||
2274 (info->max_indirect_segments &&
2275 (rinfo->shadow[i].indirect_grants == NULL)))
2277 sg_init_table(rinfo->shadow[i].sg, psegs);
2284 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2285 kfree(rinfo->shadow[i].grants_used);
2286 rinfo->shadow[i].grants_used = NULL;
2287 kfree(rinfo->shadow[i].sg);
2288 rinfo->shadow[i].sg = NULL;
2289 kfree(rinfo->shadow[i].indirect_grants);
2290 rinfo->shadow[i].indirect_grants = NULL;
2292 if (!list_empty(&rinfo->indirect_pages)) {
2293 struct page *indirect_page, *n;
2294 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2295 list_del(&indirect_page->lru);
2296 __free_page(indirect_page);
2303 * Gather all backend feature-*
2305 static void blkfront_gather_backend_features(struct blkfront_info *info)
2308 int barrier, flush, discard, persistent;
2309 unsigned int indirect_segments;
2311 info->feature_flush = 0;
2313 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2314 "feature-barrier", "%d", &barrier,
2318 * If there's no "feature-barrier" defined, then it means
2319 * we're dealing with a very old backend which writes
2320 * synchronously; nothing to do.
2322 * If there are barriers, then we use flush.
2324 if (!err && barrier)
2325 info->feature_flush = REQ_FLUSH | REQ_FUA;
2327 * And if there is "feature-flush-cache" use that above
2330 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2331 "feature-flush-cache", "%d", &flush,
2335 info->feature_flush = REQ_FLUSH;
2337 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2338 "feature-discard", "%d", &discard,
2341 if (!err && discard)
2342 blkfront_setup_discard(info);
2344 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2345 "feature-persistent", "%u", &persistent,
2348 info->feature_persistent = 0;
2350 info->feature_persistent = persistent;
2352 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2353 "feature-max-indirect-segments", "%u", &indirect_segments,
2356 info->max_indirect_segments = 0;
2358 info->max_indirect_segments = min(indirect_segments,
2359 xen_blkif_max_segments);
2363 * Invoked when the backend is finally 'ready' (and has told produced
2364 * the details about the physical device - #sectors, size, etc).
2366 static void blkfront_connect(struct blkfront_info *info)
2368 unsigned long long sectors;
2369 unsigned long sector_size;
2370 unsigned int physical_sector_size;
2374 switch (info->connected) {
2375 case BLKIF_STATE_CONNECTED:
2377 * Potentially, the back-end may be signalling
2378 * a capacity change; update the capacity.
2380 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2381 "sectors", "%Lu", §ors);
2382 if (XENBUS_EXIST_ERR(err))
2384 printk(KERN_INFO "Setting capacity to %Lu\n",
2386 set_capacity(info->gd, sectors);
2387 revalidate_disk(info->gd);
2390 case BLKIF_STATE_SUSPENDED:
2392 * If we are recovering from suspension, we need to wait
2393 * for the backend to announce it's features before
2394 * reconnecting, at least we need to know if the backend
2395 * supports indirect descriptors, and how many.
2397 blkif_recover(info);
2404 dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2405 __func__, info->xbdev->otherend);
2407 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2408 "sectors", "%llu", §ors,
2409 "info", "%u", &binfo,
2410 "sector-size", "%lu", §or_size,
2413 xenbus_dev_fatal(info->xbdev, err,
2414 "reading backend fields at %s",
2415 info->xbdev->otherend);
2420 * physcial-sector-size is a newer field, so old backends may not
2421 * provide this. Assume physical sector size to be the same as
2422 * sector_size in that case.
2424 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2425 "physical-sector-size", "%u", &physical_sector_size);
2427 physical_sector_size = sector_size;
2429 blkfront_gather_backend_features(info);
2430 for (i = 0; i < info->nr_rings; i++) {
2431 err = blkfront_setup_indirect(&info->rinfo[i]);
2433 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2434 info->xbdev->otherend);
2435 blkif_free(info, 0);
2440 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2441 physical_sector_size);
2443 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2444 info->xbdev->otherend);
2448 xenbus_switch_state(info->xbdev, XenbusStateConnected);
2450 /* Kick pending requests. */
2451 info->connected = BLKIF_STATE_CONNECTED;
2452 for (i = 0; i < info->nr_rings; i++)
2453 kick_pending_request_queues(&info->rinfo[i]);
2461 * Callback received when the backend's state changes.
2463 static void blkback_changed(struct xenbus_device *dev,
2464 enum xenbus_state backend_state)
2466 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2468 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2470 switch (backend_state) {
2471 case XenbusStateInitWait:
2472 if (dev->state != XenbusStateInitialising)
2474 if (talk_to_blkback(dev, info))
2476 case XenbusStateInitialising:
2477 case XenbusStateInitialised:
2478 case XenbusStateReconfiguring:
2479 case XenbusStateReconfigured:
2480 case XenbusStateUnknown:
2483 case XenbusStateConnected:
2485 * talk_to_blkback sets state to XenbusStateInitialised
2486 * and blkfront_connect sets it to XenbusStateConnected
2487 * (if connection went OK).
2489 * If the backend (or toolstack) decides to poke at backend
2490 * state (and re-trigger the watch by setting the state repeatedly
2491 * to XenbusStateConnected (4)) we need to deal with this.
2492 * This is allowed as this is used to communicate to the guest
2493 * that the size of disk has changed!
2495 if ((dev->state != XenbusStateInitialised) &&
2496 (dev->state != XenbusStateConnected)) {
2497 if (talk_to_blkback(dev, info))
2501 blkfront_connect(info);
2504 case XenbusStateClosed:
2505 if (dev->state == XenbusStateClosed)
2507 /* Missed the backend's Closing state -- fallthrough */
2508 case XenbusStateClosing:
2510 blkfront_closing(info);
2515 static int blkfront_remove(struct xenbus_device *xbdev)
2517 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2518 struct block_device *bdev = NULL;
2519 struct gendisk *disk;
2521 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2523 blkif_free(info, 0);
2525 mutex_lock(&info->mutex);
2529 bdev = bdget_disk(disk, 0);
2532 mutex_unlock(&info->mutex);
2540 * The xbdev was removed before we reached the Closed
2541 * state. See if it's safe to remove the disk. If the bdev
2542 * isn't closed yet, we let release take care of it.
2545 mutex_lock(&bdev->bd_mutex);
2546 info = disk->private_data;
2548 dev_warn(disk_to_dev(disk),
2549 "%s was hot-unplugged, %d stale handles\n",
2550 xbdev->nodename, bdev->bd_openers);
2552 if (info && !bdev->bd_openers) {
2553 xlvbd_release_gendisk(info);
2554 disk->private_data = NULL;
2558 mutex_unlock(&bdev->bd_mutex);
2564 static int blkfront_is_ready(struct xenbus_device *dev)
2566 struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2568 return info->is_ready && info->xbdev;
2571 static int blkif_open(struct block_device *bdev, fmode_t mode)
2573 struct gendisk *disk = bdev->bd_disk;
2574 struct blkfront_info *info;
2577 mutex_lock(&blkfront_mutex);
2579 info = disk->private_data;
2586 mutex_lock(&info->mutex);
2589 /* xbdev is closed */
2592 mutex_unlock(&info->mutex);
2595 mutex_unlock(&blkfront_mutex);
2599 static void blkif_release(struct gendisk *disk, fmode_t mode)
2601 struct blkfront_info *info = disk->private_data;
2602 struct block_device *bdev;
2603 struct xenbus_device *xbdev;
2605 mutex_lock(&blkfront_mutex);
2607 bdev = bdget_disk(disk, 0);
2610 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2613 if (bdev->bd_openers)
2617 * Check if we have been instructed to close. We will have
2618 * deferred this request, because the bdev was still open.
2621 mutex_lock(&info->mutex);
2622 xbdev = info->xbdev;
2624 if (xbdev && xbdev->state == XenbusStateClosing) {
2625 /* pending switch to state closed */
2626 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2627 xlvbd_release_gendisk(info);
2628 xenbus_frontend_closed(info->xbdev);
2631 mutex_unlock(&info->mutex);
2634 /* sudden device removal */
2635 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2636 xlvbd_release_gendisk(info);
2637 disk->private_data = NULL;
2644 mutex_unlock(&blkfront_mutex);
2647 static const struct block_device_operations xlvbd_block_fops =
2649 .owner = THIS_MODULE,
2651 .release = blkif_release,
2652 .getgeo = blkif_getgeo,
2653 .ioctl = blkif_ioctl,
2657 static const struct xenbus_device_id blkfront_ids[] = {
2662 static struct xenbus_driver blkfront_driver = {
2663 .ids = blkfront_ids,
2664 .probe = blkfront_probe,
2665 .remove = blkfront_remove,
2666 .resume = blkfront_resume,
2667 .otherend_changed = blkback_changed,
2668 .is_ready = blkfront_is_ready,
2671 static int __init xlblk_init(void)
2674 int nr_cpus = num_online_cpus();
2679 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2680 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2681 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2682 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2685 if (xen_blkif_max_queues > nr_cpus) {
2686 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2687 xen_blkif_max_queues, nr_cpus);
2688 xen_blkif_max_queues = nr_cpus;
2691 if (!xen_has_pv_disk_devices())
2694 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2695 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2696 XENVBD_MAJOR, DEV_NAME);
2700 ret = xenbus_register_frontend(&blkfront_driver);
2702 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2708 module_init(xlblk_init);
2711 static void __exit xlblk_exit(void)
2713 xenbus_unregister_driver(&blkfront_driver);
2714 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2717 module_exit(xlblk_exit);
2719 MODULE_DESCRIPTION("Xen virtual block device frontend");
2720 MODULE_LICENSE("GPL");
2721 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2722 MODULE_ALIAS("xen:vbd");
2723 MODULE_ALIAS("xenblk");