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
, xen_blkif_max_segments
, int, S_IRUGO
);
129 MODULE_PARM_DESC(max
, "Maximum amount of segments in indirect requests (default is 32)");
131 static unsigned int xen_blkif_max_queues
= 4;
132 module_param_named(max_queues
, xen_blkif_max_queues
, uint
, S_IRUGO
);
133 MODULE_PARM_DESC(max_queues
, "Maximum number of hardware queues/rings used per virtual disk");
136 * Maximum order of pages to be used for the shared ring between front and
137 * backend, 4KB page granularity is used.
139 static unsigned int xen_blkif_max_ring_order
;
140 module_param_named(max_ring_page_order
, xen_blkif_max_ring_order
, int, S_IRUGO
);
141 MODULE_PARM_DESC(max_ring_page_order
, "Maximum order of pages to be used for the shared ring");
143 #define BLK_RING_SIZE(info) \
144 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
146 #define BLK_MAX_RING_SIZE \
147 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
150 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
151 * characters are enough. Define to 20 to keep consistent with backend.
153 #define RINGREF_NAME_LEN (20)
155 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
157 #define QUEUE_NAME_LEN (17)
161 * Every blkfront device can associate with one or more blkfront_ring_info,
162 * depending on how many hardware queues/rings to be used.
164 struct blkfront_ring_info
{
165 /* Lock to protect data in every ring buffer. */
166 spinlock_t ring_lock
;
167 struct blkif_front_ring ring
;
168 unsigned int ring_ref
[XENBUS_MAX_RING_GRANTS
];
169 unsigned int evtchn
, irq
;
170 struct work_struct work
;
171 struct gnttab_free_callback callback
;
172 struct blk_shadow shadow
[BLK_MAX_RING_SIZE
];
173 struct list_head indirect_pages
;
174 struct list_head grants
;
175 unsigned int persistent_gnts_c
;
176 unsigned long shadow_free
;
177 struct blkfront_info
*dev_info
;
181 * We have one of these per vbd, whether ide, scsi or 'other'. They
182 * hang in private_data off the gendisk structure. We may end up
183 * putting all kinds of interesting stuff here :-)
188 struct xenbus_device
*xbdev
;
192 enum blkif_state connected
;
193 /* Number of pages per ring buffer. */
194 unsigned int nr_ring_pages
;
195 struct request_queue
*rq
;
196 unsigned int feature_flush
;
197 unsigned int feature_discard
:1;
198 unsigned int feature_secdiscard
:1;
199 unsigned int discard_granularity
;
200 unsigned int discard_alignment
;
201 unsigned int feature_persistent
:1;
202 /* Number of 4KB segments handled */
203 unsigned int max_indirect_segments
;
205 struct blk_mq_tag_set tag_set
;
206 struct blkfront_ring_info
*rinfo
;
207 unsigned int nr_rings
;
210 static unsigned int nr_minors
;
211 static unsigned long *minors
;
212 static DEFINE_SPINLOCK(minor_lock
);
214 #define GRANT_INVALID_REF 0
216 #define PARTS_PER_DISK 16
217 #define PARTS_PER_EXT_DISK 256
219 #define BLKIF_MAJOR(dev) ((dev)>>8)
220 #define BLKIF_MINOR(dev) ((dev) & 0xff)
223 #define EXTENDED (1<<EXT_SHIFT)
224 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
225 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
226 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
227 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
228 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
229 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
231 #define DEV_NAME "xvd" /* name in /dev */
234 * Grants are always the same size as a Xen page (i.e 4KB).
235 * A physical segment is always the same size as a Linux page.
236 * Number of grants per physical segment
238 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
240 #define GRANTS_PER_INDIRECT_FRAME \
241 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
243 #define PSEGS_PER_INDIRECT_FRAME \
244 (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
246 #define INDIRECT_GREFS(_grants) \
247 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
249 #define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG)
251 static int blkfront_setup_indirect(struct blkfront_ring_info
*rinfo
);
252 static void blkfront_gather_backend_features(struct blkfront_info
*info
);
254 static int get_id_from_freelist(struct blkfront_ring_info
*rinfo
)
256 unsigned long free
= rinfo
->shadow_free
;
258 BUG_ON(free
>= BLK_RING_SIZE(rinfo
->dev_info
));
259 rinfo
->shadow_free
= rinfo
->shadow
[free
].req
.u
.rw
.id
;
260 rinfo
->shadow
[free
].req
.u
.rw
.id
= 0x0fffffee; /* debug */
264 static int add_id_to_freelist(struct blkfront_ring_info
*rinfo
,
267 if (rinfo
->shadow
[id
].req
.u
.rw
.id
!= id
)
269 if (rinfo
->shadow
[id
].request
== NULL
)
271 rinfo
->shadow
[id
].req
.u
.rw
.id
= rinfo
->shadow_free
;
272 rinfo
->shadow
[id
].request
= NULL
;
273 rinfo
->shadow_free
= id
;
277 static int fill_grant_buffer(struct blkfront_ring_info
*rinfo
, int num
)
279 struct blkfront_info
*info
= rinfo
->dev_info
;
280 struct page
*granted_page
;
281 struct grant
*gnt_list_entry
, *n
;
285 gnt_list_entry
= kzalloc(sizeof(struct grant
), GFP_NOIO
);
289 if (info
->feature_persistent
) {
290 granted_page
= alloc_page(GFP_NOIO
);
292 kfree(gnt_list_entry
);
295 gnt_list_entry
->page
= granted_page
;
298 gnt_list_entry
->gref
= GRANT_INVALID_REF
;
299 list_add(&gnt_list_entry
->node
, &rinfo
->grants
);
306 list_for_each_entry_safe(gnt_list_entry
, n
,
307 &rinfo
->grants
, node
) {
308 list_del(&gnt_list_entry
->node
);
309 if (info
->feature_persistent
)
310 __free_page(gnt_list_entry
->page
);
311 kfree(gnt_list_entry
);
318 static struct grant
*get_free_grant(struct blkfront_ring_info
*rinfo
)
320 struct grant
*gnt_list_entry
;
322 BUG_ON(list_empty(&rinfo
->grants
));
323 gnt_list_entry
= list_first_entry(&rinfo
->grants
, struct grant
,
325 list_del(&gnt_list_entry
->node
);
327 if (gnt_list_entry
->gref
!= GRANT_INVALID_REF
)
328 rinfo
->persistent_gnts_c
--;
330 return gnt_list_entry
;
333 static inline void grant_foreign_access(const struct grant
*gnt_list_entry
,
334 const struct blkfront_info
*info
)
336 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry
->gref
,
337 info
->xbdev
->otherend_id
,
338 gnt_list_entry
->page
,
342 static struct grant
*get_grant(grant_ref_t
*gref_head
,
344 struct blkfront_ring_info
*rinfo
)
346 struct grant
*gnt_list_entry
= get_free_grant(rinfo
);
347 struct blkfront_info
*info
= rinfo
->dev_info
;
349 if (gnt_list_entry
->gref
!= GRANT_INVALID_REF
)
350 return gnt_list_entry
;
352 /* Assign a gref to this page */
353 gnt_list_entry
->gref
= gnttab_claim_grant_reference(gref_head
);
354 BUG_ON(gnt_list_entry
->gref
== -ENOSPC
);
355 if (info
->feature_persistent
)
356 grant_foreign_access(gnt_list_entry
, info
);
358 /* Grant access to the GFN passed by the caller */
359 gnttab_grant_foreign_access_ref(gnt_list_entry
->gref
,
360 info
->xbdev
->otherend_id
,
364 return gnt_list_entry
;
367 static struct grant
*get_indirect_grant(grant_ref_t
*gref_head
,
368 struct blkfront_ring_info
*rinfo
)
370 struct grant
*gnt_list_entry
= get_free_grant(rinfo
);
371 struct blkfront_info
*info
= rinfo
->dev_info
;
373 if (gnt_list_entry
->gref
!= GRANT_INVALID_REF
)
374 return gnt_list_entry
;
376 /* Assign a gref to this page */
377 gnt_list_entry
->gref
= gnttab_claim_grant_reference(gref_head
);
378 BUG_ON(gnt_list_entry
->gref
== -ENOSPC
);
379 if (!info
->feature_persistent
) {
380 struct page
*indirect_page
;
382 /* Fetch a pre-allocated page to use for indirect grefs */
383 BUG_ON(list_empty(&rinfo
->indirect_pages
));
384 indirect_page
= list_first_entry(&rinfo
->indirect_pages
,
386 list_del(&indirect_page
->lru
);
387 gnt_list_entry
->page
= indirect_page
;
389 grant_foreign_access(gnt_list_entry
, info
);
391 return gnt_list_entry
;
394 static const char *op_name(int op
)
396 static const char *const names
[] = {
397 [BLKIF_OP_READ
] = "read",
398 [BLKIF_OP_WRITE
] = "write",
399 [BLKIF_OP_WRITE_BARRIER
] = "barrier",
400 [BLKIF_OP_FLUSH_DISKCACHE
] = "flush",
401 [BLKIF_OP_DISCARD
] = "discard" };
403 if (op
< 0 || op
>= ARRAY_SIZE(names
))
411 static int xlbd_reserve_minors(unsigned int minor
, unsigned int nr
)
413 unsigned int end
= minor
+ nr
;
416 if (end
> nr_minors
) {
417 unsigned long *bitmap
, *old
;
419 bitmap
= kcalloc(BITS_TO_LONGS(end
), sizeof(*bitmap
),
424 spin_lock(&minor_lock
);
425 if (end
> nr_minors
) {
427 memcpy(bitmap
, minors
,
428 BITS_TO_LONGS(nr_minors
) * sizeof(*bitmap
));
430 nr_minors
= BITS_TO_LONGS(end
) * BITS_PER_LONG
;
433 spin_unlock(&minor_lock
);
437 spin_lock(&minor_lock
);
438 if (find_next_bit(minors
, end
, minor
) >= end
) {
439 bitmap_set(minors
, minor
, nr
);
443 spin_unlock(&minor_lock
);
448 static void xlbd_release_minors(unsigned int minor
, unsigned int nr
)
450 unsigned int end
= minor
+ nr
;
452 BUG_ON(end
> nr_minors
);
453 spin_lock(&minor_lock
);
454 bitmap_clear(minors
, minor
, nr
);
455 spin_unlock(&minor_lock
);
458 static void blkif_restart_queue_callback(void *arg
)
460 struct blkfront_ring_info
*rinfo
= (struct blkfront_ring_info
*)arg
;
461 schedule_work(&rinfo
->work
);
464 static int blkif_getgeo(struct block_device
*bd
, struct hd_geometry
*hg
)
466 /* We don't have real geometry info, but let's at least return
467 values consistent with the size of the device */
468 sector_t nsect
= get_capacity(bd
->bd_disk
);
469 sector_t cylinders
= nsect
;
473 sector_div(cylinders
, hg
->heads
* hg
->sectors
);
474 hg
->cylinders
= cylinders
;
475 if ((sector_t
)(hg
->cylinders
+ 1) * hg
->heads
* hg
->sectors
< nsect
)
476 hg
->cylinders
= 0xffff;
480 static int blkif_ioctl(struct block_device
*bdev
, fmode_t mode
,
481 unsigned command
, unsigned long argument
)
483 struct blkfront_info
*info
= bdev
->bd_disk
->private_data
;
486 dev_dbg(&info
->xbdev
->dev
, "command: 0x%x, argument: 0x%lx\n",
487 command
, (long)argument
);
490 case CDROMMULTISESSION
:
491 dev_dbg(&info
->xbdev
->dev
, "FIXME: support multisession CDs later\n");
492 for (i
= 0; i
< sizeof(struct cdrom_multisession
); i
++)
493 if (put_user(0, (char __user
*)(argument
+ i
)))
497 case CDROM_GET_CAPABILITY
: {
498 struct gendisk
*gd
= info
->gd
;
499 if (gd
->flags
& GENHD_FL_CD
)
505 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
507 return -EINVAL
; /* same return as native Linux */
513 static unsigned long blkif_ring_get_request(struct blkfront_ring_info
*rinfo
,
515 struct blkif_request
**ring_req
)
519 *ring_req
= RING_GET_REQUEST(&rinfo
->ring
, rinfo
->ring
.req_prod_pvt
);
520 rinfo
->ring
.req_prod_pvt
++;
522 id
= get_id_from_freelist(rinfo
);
523 rinfo
->shadow
[id
].request
= req
;
524 rinfo
->shadow
[id
].status
= REQ_WAITING
;
525 rinfo
->shadow
[id
].associated_id
= NO_ASSOCIATED_ID
;
527 (*ring_req
)->u
.rw
.id
= id
;
532 static int blkif_queue_discard_req(struct request
*req
, struct blkfront_ring_info
*rinfo
)
534 struct blkfront_info
*info
= rinfo
->dev_info
;
535 struct blkif_request
*ring_req
;
538 /* Fill out a communications ring structure. */
539 id
= blkif_ring_get_request(rinfo
, req
, &ring_req
);
541 ring_req
->operation
= BLKIF_OP_DISCARD
;
542 ring_req
->u
.discard
.nr_sectors
= blk_rq_sectors(req
);
543 ring_req
->u
.discard
.id
= id
;
544 ring_req
->u
.discard
.sector_number
= (blkif_sector_t
)blk_rq_pos(req
);
545 if ((req
->cmd_flags
& REQ_SECURE
) && info
->feature_secdiscard
)
546 ring_req
->u
.discard
.flag
= BLKIF_DISCARD_SECURE
;
548 ring_req
->u
.discard
.flag
= 0;
550 /* Keep a private copy so we can reissue requests when recovering. */
551 rinfo
->shadow
[id
].req
= *ring_req
;
556 struct setup_rw_req
{
557 unsigned int grant_idx
;
558 struct blkif_request_segment
*segments
;
559 struct blkfront_ring_info
*rinfo
;
560 struct blkif_request
*ring_req
;
561 grant_ref_t gref_head
;
563 /* Only used when persistent grant is used and it's a read request */
565 unsigned int bvec_off
;
568 bool require_extra_req
;
569 struct blkif_request
*extra_ring_req
;
572 static void blkif_setup_rw_req_grant(unsigned long gfn
, unsigned int offset
,
573 unsigned int len
, void *data
)
575 struct setup_rw_req
*setup
= data
;
577 struct grant
*gnt_list_entry
;
578 unsigned int fsect
, lsect
;
579 /* Convenient aliases */
580 unsigned int grant_idx
= setup
->grant_idx
;
581 struct blkif_request
*ring_req
= setup
->ring_req
;
582 struct blkfront_ring_info
*rinfo
= setup
->rinfo
;
584 * We always use the shadow of the first request to store the list
585 * of grant associated to the block I/O request. This made the
586 * completion more easy to handle even if the block I/O request is
589 struct blk_shadow
*shadow
= &rinfo
->shadow
[setup
->id
];
591 if (unlikely(setup
->require_extra_req
&&
592 grant_idx
>= BLKIF_MAX_SEGMENTS_PER_REQUEST
)) {
594 * We are using the second request, setup grant_idx
595 * to be the index of the segment array.
597 grant_idx
-= BLKIF_MAX_SEGMENTS_PER_REQUEST
;
598 ring_req
= setup
->extra_ring_req
;
601 if ((ring_req
->operation
== BLKIF_OP_INDIRECT
) &&
602 (grant_idx
% GRANTS_PER_INDIRECT_FRAME
== 0)) {
604 kunmap_atomic(setup
->segments
);
606 n
= grant_idx
/ GRANTS_PER_INDIRECT_FRAME
;
607 gnt_list_entry
= get_indirect_grant(&setup
->gref_head
, rinfo
);
608 shadow
->indirect_grants
[n
] = gnt_list_entry
;
609 setup
->segments
= kmap_atomic(gnt_list_entry
->page
);
610 ring_req
->u
.indirect
.indirect_grefs
[n
] = gnt_list_entry
->gref
;
613 gnt_list_entry
= get_grant(&setup
->gref_head
, gfn
, rinfo
);
614 ref
= gnt_list_entry
->gref
;
616 * All the grants are stored in the shadow of the first
617 * request. Therefore we have to use the global index.
619 shadow
->grants_used
[setup
->grant_idx
] = gnt_list_entry
;
621 if (setup
->need_copy
) {
624 shared_data
= kmap_atomic(gnt_list_entry
->page
);
626 * this does not wipe data stored outside the
627 * range sg->offset..sg->offset+sg->length.
628 * Therefore, blkback *could* see data from
629 * previous requests. This is OK as long as
630 * persistent grants are shared with just one
631 * domain. It may need refactoring if this
634 memcpy(shared_data
+ offset
,
635 setup
->bvec_data
+ setup
->bvec_off
,
638 kunmap_atomic(shared_data
);
639 setup
->bvec_off
+= len
;
643 lsect
= fsect
+ (len
>> 9) - 1;
644 if (ring_req
->operation
!= BLKIF_OP_INDIRECT
) {
645 ring_req
->u
.rw
.seg
[grant_idx
] =
646 (struct blkif_request_segment
) {
649 .last_sect
= lsect
};
651 setup
->segments
[grant_idx
% GRANTS_PER_INDIRECT_FRAME
] =
652 (struct blkif_request_segment
) {
655 .last_sect
= lsect
};
658 (setup
->grant_idx
)++;
661 static void blkif_setup_extra_req(struct blkif_request
*first
,
662 struct blkif_request
*second
)
664 uint16_t nr_segments
= first
->u
.rw
.nr_segments
;
667 * The second request is only present when the first request uses
668 * all its segments. It's always the continuity of the first one.
670 first
->u
.rw
.nr_segments
= BLKIF_MAX_SEGMENTS_PER_REQUEST
;
672 second
->u
.rw
.nr_segments
= nr_segments
- BLKIF_MAX_SEGMENTS_PER_REQUEST
;
673 second
->u
.rw
.sector_number
= first
->u
.rw
.sector_number
+
674 (BLKIF_MAX_SEGMENTS_PER_REQUEST
* XEN_PAGE_SIZE
) / 512;
676 second
->u
.rw
.handle
= first
->u
.rw
.handle
;
677 second
->operation
= first
->operation
;
680 static int blkif_queue_rw_req(struct request
*req
, struct blkfront_ring_info
*rinfo
)
682 struct blkfront_info
*info
= rinfo
->dev_info
;
683 struct blkif_request
*ring_req
, *extra_ring_req
= NULL
;
684 unsigned long id
, extra_id
= NO_ASSOCIATED_ID
;
685 bool require_extra_req
= false;
687 struct setup_rw_req setup
= {
691 .need_copy
= rq_data_dir(req
) && info
->feature_persistent
,
695 * Used to store if we are able to queue the request by just using
696 * existing persistent grants, or if we have to get new grants,
697 * as there are not sufficiently many free.
699 struct scatterlist
*sg
;
700 int num_sg
, max_grefs
, num_grant
;
702 max_grefs
= req
->nr_phys_segments
* GRANTS_PER_PSEG
;
703 if (max_grefs
> BLKIF_MAX_SEGMENTS_PER_REQUEST
)
705 * If we are using indirect segments we need to account
706 * for the indirect grefs used in the request.
708 max_grefs
+= INDIRECT_GREFS(max_grefs
);
711 * We have to reserve 'max_grefs' grants because persistent
712 * grants are shared by all rings.
715 if (gnttab_alloc_grant_references(max_grefs
, &setup
.gref_head
) < 0) {
716 gnttab_request_free_callback(
718 blkif_restart_queue_callback
,
724 /* Fill out a communications ring structure. */
725 id
= blkif_ring_get_request(rinfo
, req
, &ring_req
);
727 num_sg
= blk_rq_map_sg(req
->q
, req
, rinfo
->shadow
[id
].sg
);
729 /* Calculate the number of grant used */
730 for_each_sg(rinfo
->shadow
[id
].sg
, sg
, num_sg
, i
)
731 num_grant
+= gnttab_count_grant(sg
->offset
, sg
->length
);
733 require_extra_req
= info
->max_indirect_segments
== 0 &&
734 num_grant
> BLKIF_MAX_SEGMENTS_PER_REQUEST
;
735 BUG_ON(!HAS_EXTRA_REQ
&& require_extra_req
);
737 rinfo
->shadow
[id
].num_sg
= num_sg
;
738 if (num_grant
> BLKIF_MAX_SEGMENTS_PER_REQUEST
&&
739 likely(!require_extra_req
)) {
741 * The indirect operation can only be a BLKIF_OP_READ or
744 BUG_ON(req
->cmd_flags
& (REQ_FLUSH
| REQ_FUA
));
745 ring_req
->operation
= BLKIF_OP_INDIRECT
;
746 ring_req
->u
.indirect
.indirect_op
= rq_data_dir(req
) ?
747 BLKIF_OP_WRITE
: BLKIF_OP_READ
;
748 ring_req
->u
.indirect
.sector_number
= (blkif_sector_t
)blk_rq_pos(req
);
749 ring_req
->u
.indirect
.handle
= info
->handle
;
750 ring_req
->u
.indirect
.nr_segments
= num_grant
;
752 ring_req
->u
.rw
.sector_number
= (blkif_sector_t
)blk_rq_pos(req
);
753 ring_req
->u
.rw
.handle
= info
->handle
;
754 ring_req
->operation
= rq_data_dir(req
) ?
755 BLKIF_OP_WRITE
: BLKIF_OP_READ
;
756 if (req
->cmd_flags
& (REQ_FLUSH
| REQ_FUA
)) {
758 * Ideally we can do an unordered flush-to-disk.
759 * In case the backend onlysupports barriers, use that.
760 * A barrier request a superset of FUA, so we can
761 * implement it the same way. (It's also a FLUSH+FUA,
762 * since it is guaranteed ordered WRT previous writes.)
764 switch (info
->feature_flush
&
765 ((REQ_FLUSH
|REQ_FUA
))) {
766 case REQ_FLUSH
|REQ_FUA
:
767 ring_req
->operation
=
768 BLKIF_OP_WRITE_BARRIER
;
771 ring_req
->operation
=
772 BLKIF_OP_FLUSH_DISKCACHE
;
775 ring_req
->operation
= 0;
778 ring_req
->u
.rw
.nr_segments
= num_grant
;
779 if (unlikely(require_extra_req
)) {
780 extra_id
= blkif_ring_get_request(rinfo
, req
,
783 * Only the first request contains the scatter-gather
786 rinfo
->shadow
[extra_id
].num_sg
= 0;
788 blkif_setup_extra_req(ring_req
, extra_ring_req
);
790 /* Link the 2 requests together */
791 rinfo
->shadow
[extra_id
].associated_id
= id
;
792 rinfo
->shadow
[id
].associated_id
= extra_id
;
796 setup
.ring_req
= ring_req
;
799 setup
.require_extra_req
= require_extra_req
;
800 if (unlikely(require_extra_req
))
801 setup
.extra_ring_req
= extra_ring_req
;
803 for_each_sg(rinfo
->shadow
[id
].sg
, sg
, num_sg
, i
) {
804 BUG_ON(sg
->offset
+ sg
->length
> PAGE_SIZE
);
806 if (setup
.need_copy
) {
807 setup
.bvec_off
= sg
->offset
;
808 setup
.bvec_data
= kmap_atomic(sg_page(sg
));
811 gnttab_foreach_grant_in_range(sg_page(sg
),
814 blkif_setup_rw_req_grant
,
818 kunmap_atomic(setup
.bvec_data
);
821 kunmap_atomic(setup
.segments
);
823 /* Keep a private copy so we can reissue requests when recovering. */
824 rinfo
->shadow
[id
].req
= *ring_req
;
825 if (unlikely(require_extra_req
))
826 rinfo
->shadow
[extra_id
].req
= *extra_ring_req
;
829 gnttab_free_grant_references(setup
.gref_head
);
835 * Generate a Xen blkfront IO request from a blk layer request. Reads
836 * and writes are handled as expected.
838 * @req: a request struct
840 static int blkif_queue_request(struct request
*req
, struct blkfront_ring_info
*rinfo
)
842 if (unlikely(rinfo
->dev_info
->connected
!= BLKIF_STATE_CONNECTED
))
845 if (unlikely(req
->cmd_flags
& (REQ_DISCARD
| REQ_SECURE
)))
846 return blkif_queue_discard_req(req
, rinfo
);
848 return blkif_queue_rw_req(req
, rinfo
);
851 static inline void flush_requests(struct blkfront_ring_info
*rinfo
)
855 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo
->ring
, notify
);
858 notify_remote_via_irq(rinfo
->irq
);
861 static inline bool blkif_request_flush_invalid(struct request
*req
,
862 struct blkfront_info
*info
)
864 return ((req
->cmd_type
!= REQ_TYPE_FS
) ||
865 ((req
->cmd_flags
& REQ_FLUSH
) &&
866 !(info
->feature_flush
& REQ_FLUSH
)) ||
867 ((req
->cmd_flags
& REQ_FUA
) &&
868 !(info
->feature_flush
& REQ_FUA
)));
871 static int blkif_queue_rq(struct blk_mq_hw_ctx
*hctx
,
872 const struct blk_mq_queue_data
*qd
)
875 struct blkfront_ring_info
*rinfo
= (struct blkfront_ring_info
*)hctx
->driver_data
;
877 blk_mq_start_request(qd
->rq
);
878 spin_lock_irqsave(&rinfo
->ring_lock
, flags
);
879 if (RING_FULL(&rinfo
->ring
))
882 if (blkif_request_flush_invalid(qd
->rq
, rinfo
->dev_info
))
885 if (blkif_queue_request(qd
->rq
, rinfo
))
888 flush_requests(rinfo
);
889 spin_unlock_irqrestore(&rinfo
->ring_lock
, flags
);
890 return BLK_MQ_RQ_QUEUE_OK
;
893 spin_unlock_irqrestore(&rinfo
->ring_lock
, flags
);
894 return BLK_MQ_RQ_QUEUE_ERROR
;
897 spin_unlock_irqrestore(&rinfo
->ring_lock
, flags
);
898 blk_mq_stop_hw_queue(hctx
);
899 return BLK_MQ_RQ_QUEUE_BUSY
;
902 static int blk_mq_init_hctx(struct blk_mq_hw_ctx
*hctx
, void *data
,
905 struct blkfront_info
*info
= (struct blkfront_info
*)data
;
907 BUG_ON(info
->nr_rings
<= index
);
908 hctx
->driver_data
= &info
->rinfo
[index
];
912 static struct blk_mq_ops blkfront_mq_ops
= {
913 .queue_rq
= blkif_queue_rq
,
914 .map_queue
= blk_mq_map_queue
,
915 .init_hctx
= blk_mq_init_hctx
,
918 static int xlvbd_init_blk_queue(struct gendisk
*gd
, u16 sector_size
,
919 unsigned int physical_sector_size
,
920 unsigned int segments
)
922 struct request_queue
*rq
;
923 struct blkfront_info
*info
= gd
->private_data
;
925 memset(&info
->tag_set
, 0, sizeof(info
->tag_set
));
926 info
->tag_set
.ops
= &blkfront_mq_ops
;
927 info
->tag_set
.nr_hw_queues
= info
->nr_rings
;
928 if (HAS_EXTRA_REQ
&& info
->max_indirect_segments
== 0) {
930 * When indirect descriptior is not supported, the I/O request
931 * will be split between multiple request in the ring.
932 * To avoid problems when sending the request, divide by
933 * 2 the depth of the queue.
935 info
->tag_set
.queue_depth
= BLK_RING_SIZE(info
) / 2;
937 info
->tag_set
.queue_depth
= BLK_RING_SIZE(info
);
938 info
->tag_set
.numa_node
= NUMA_NO_NODE
;
939 info
->tag_set
.flags
= BLK_MQ_F_SHOULD_MERGE
| BLK_MQ_F_SG_MERGE
;
940 info
->tag_set
.cmd_size
= 0;
941 info
->tag_set
.driver_data
= info
;
943 if (blk_mq_alloc_tag_set(&info
->tag_set
))
945 rq
= blk_mq_init_queue(&info
->tag_set
);
947 blk_mq_free_tag_set(&info
->tag_set
);
951 queue_flag_set_unlocked(QUEUE_FLAG_VIRT
, rq
);
953 if (info
->feature_discard
) {
954 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD
, rq
);
955 blk_queue_max_discard_sectors(rq
, get_capacity(gd
));
956 rq
->limits
.discard_granularity
= info
->discard_granularity
;
957 rq
->limits
.discard_alignment
= info
->discard_alignment
;
958 if (info
->feature_secdiscard
)
959 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD
, rq
);
962 /* Hard sector size and max sectors impersonate the equiv. hardware. */
963 blk_queue_logical_block_size(rq
, sector_size
);
964 blk_queue_physical_block_size(rq
, physical_sector_size
);
965 blk_queue_max_hw_sectors(rq
, (segments
* XEN_PAGE_SIZE
) / 512);
967 /* Each segment in a request is up to an aligned page in size. */
968 blk_queue_segment_boundary(rq
, PAGE_SIZE
- 1);
969 blk_queue_max_segment_size(rq
, PAGE_SIZE
);
971 /* Ensure a merged request will fit in a single I/O ring slot. */
972 blk_queue_max_segments(rq
, segments
/ GRANTS_PER_PSEG
);
974 /* Make sure buffer addresses are sector-aligned. */
975 blk_queue_dma_alignment(rq
, 511);
977 /* Make sure we don't use bounce buffers. */
978 blk_queue_bounce_limit(rq
, BLK_BOUNCE_ANY
);
985 static const char *flush_info(unsigned int feature_flush
)
987 switch (feature_flush
& ((REQ_FLUSH
| REQ_FUA
))) {
988 case REQ_FLUSH
|REQ_FUA
:
989 return "barrier: enabled;";
991 return "flush diskcache: enabled;";
993 return "barrier or flush: disabled;";
997 static void xlvbd_flush(struct blkfront_info
*info
)
999 blk_queue_flush(info
->rq
, info
->feature_flush
);
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
);
1877 * Entry point to this code when a new device is created. Allocate the basic
1878 * structures and the ring buffer for communication with the backend, and
1879 * inform the backend of the appropriate details for those. Switch to
1880 * Initialised state.
1882 static int blkfront_probe(struct xenbus_device
*dev
,
1883 const struct xenbus_device_id
*id
)
1886 unsigned int r_index
;
1887 struct blkfront_info
*info
;
1888 unsigned int backend_max_queues
= 0;
1890 /* FIXME: Use dynamic device id if this is not set. */
1891 err
= xenbus_scanf(XBT_NIL
, dev
->nodename
,
1892 "virtual-device", "%i", &vdevice
);
1894 /* go looking in the extended area instead */
1895 err
= xenbus_scanf(XBT_NIL
, dev
->nodename
, "virtual-device-ext",
1898 xenbus_dev_fatal(dev
, err
, "reading virtual-device");
1903 if (xen_hvm_domain()) {
1906 /* no unplug has been done: do not hook devices != xen vbds */
1907 if (xen_has_pv_and_legacy_disk_devices()) {
1910 if (!VDEV_IS_EXTENDED(vdevice
))
1911 major
= BLKIF_MAJOR(vdevice
);
1913 major
= XENVBD_MAJOR
;
1915 if (major
!= XENVBD_MAJOR
) {
1917 "%s: HVM does not support vbd %d as xen block device\n",
1922 /* do not create a PV cdrom device if we are an HVM guest */
1923 type
= xenbus_read(XBT_NIL
, dev
->nodename
, "device-type", &len
);
1926 if (strncmp(type
, "cdrom", 5) == 0) {
1932 info
= kzalloc(sizeof(*info
), GFP_KERNEL
);
1934 xenbus_dev_fatal(dev
, -ENOMEM
, "allocating info structure");
1939 /* Check if backend supports multiple queues. */
1940 err
= xenbus_scanf(XBT_NIL
, info
->xbdev
->otherend
,
1941 "multi-queue-max-queues", "%u", &backend_max_queues
);
1943 backend_max_queues
= 1;
1945 info
->nr_rings
= min(backend_max_queues
, xen_blkif_max_queues
);
1946 /* We need at least one ring. */
1947 if (!info
->nr_rings
)
1950 info
->rinfo
= kzalloc(sizeof(struct blkfront_ring_info
) * info
->nr_rings
, GFP_KERNEL
);
1952 xenbus_dev_fatal(dev
, -ENOMEM
, "allocating ring_info structure");
1957 for (r_index
= 0; r_index
< info
->nr_rings
; r_index
++) {
1958 struct blkfront_ring_info
*rinfo
;
1960 rinfo
= &info
->rinfo
[r_index
];
1961 INIT_LIST_HEAD(&rinfo
->indirect_pages
);
1962 INIT_LIST_HEAD(&rinfo
->grants
);
1963 rinfo
->dev_info
= info
;
1964 INIT_WORK(&rinfo
->work
, blkif_restart_queue
);
1965 spin_lock_init(&rinfo
->ring_lock
);
1968 mutex_init(&info
->mutex
);
1969 info
->vdevice
= vdevice
;
1970 info
->connected
= BLKIF_STATE_DISCONNECTED
;
1972 /* Front end dir is a number, which is used as the id. */
1973 info
->handle
= simple_strtoul(strrchr(dev
->nodename
, '/')+1, NULL
, 0);
1974 dev_set_drvdata(&dev
->dev
, info
);
1979 static void split_bio_end(struct bio
*bio
)
1981 struct split_bio
*split_bio
= bio
->bi_private
;
1983 if (atomic_dec_and_test(&split_bio
->pending
)) {
1984 split_bio
->bio
->bi_phys_segments
= 0;
1985 split_bio
->bio
->bi_error
= bio
->bi_error
;
1986 bio_endio(split_bio
->bio
);
1992 static int blkif_recover(struct blkfront_info
*info
)
1994 unsigned int i
, r_index
;
1995 struct request
*req
, *n
;
1996 struct blk_shadow
*copy
;
1998 struct bio
*bio
, *cloned_bio
;
1999 struct bio_list bio_list
, merge_bio
;
2000 unsigned int segs
, offset
;
2002 struct split_bio
*split_bio
;
2003 struct list_head requests
;
2005 blkfront_gather_backend_features(info
);
2006 segs
= info
->max_indirect_segments
? : BLKIF_MAX_SEGMENTS_PER_REQUEST
;
2007 blk_queue_max_segments(info
->rq
, segs
);
2008 bio_list_init(&bio_list
);
2009 INIT_LIST_HEAD(&requests
);
2011 for (r_index
= 0; r_index
< info
->nr_rings
; r_index
++) {
2012 struct blkfront_ring_info
*rinfo
;
2014 rinfo
= &info
->rinfo
[r_index
];
2015 /* Stage 1: Make a safe copy of the shadow state. */
2016 copy
= kmemdup(rinfo
->shadow
, sizeof(rinfo
->shadow
),
2017 GFP_NOIO
| __GFP_REPEAT
| __GFP_HIGH
);
2021 /* Stage 2: Set up free list. */
2022 memset(&rinfo
->shadow
, 0, sizeof(rinfo
->shadow
));
2023 for (i
= 0; i
< BLK_RING_SIZE(info
); i
++)
2024 rinfo
->shadow
[i
].req
.u
.rw
.id
= i
+1;
2025 rinfo
->shadow_free
= rinfo
->ring
.req_prod_pvt
;
2026 rinfo
->shadow
[BLK_RING_SIZE(info
)-1].req
.u
.rw
.id
= 0x0fffffff;
2028 rc
= blkfront_setup_indirect(rinfo
);
2034 for (i
= 0; i
< BLK_RING_SIZE(info
); i
++) {
2036 if (!copy
[i
].request
)
2040 * Get the bios in the request so we can re-queue them.
2042 if (copy
[i
].request
->cmd_flags
&
2043 (REQ_FLUSH
| REQ_FUA
| REQ_DISCARD
| REQ_SECURE
)) {
2045 * Flush operations don't contain bios, so
2046 * we need to requeue the whole request
2048 list_add(©
[i
].request
->queuelist
, &requests
);
2051 merge_bio
.head
= copy
[i
].request
->bio
;
2052 merge_bio
.tail
= copy
[i
].request
->biotail
;
2053 bio_list_merge(&bio_list
, &merge_bio
);
2054 copy
[i
].request
->bio
= NULL
;
2055 blk_end_request_all(copy
[i
].request
, 0);
2060 xenbus_switch_state(info
->xbdev
, XenbusStateConnected
);
2062 /* Now safe for us to use the shared ring */
2063 info
->connected
= BLKIF_STATE_CONNECTED
;
2065 for (r_index
= 0; r_index
< info
->nr_rings
; r_index
++) {
2066 struct blkfront_ring_info
*rinfo
;
2068 rinfo
= &info
->rinfo
[r_index
];
2069 /* Kick any other new requests queued since we resumed */
2070 kick_pending_request_queues(rinfo
);
2073 list_for_each_entry_safe(req
, n
, &requests
, queuelist
) {
2074 /* Requeue pending requests (flush or discard) */
2075 list_del_init(&req
->queuelist
);
2076 BUG_ON(req
->nr_phys_segments
> segs
);
2077 blk_mq_requeue_request(req
);
2079 blk_mq_kick_requeue_list(info
->rq
);
2081 while ((bio
= bio_list_pop(&bio_list
)) != NULL
) {
2082 /* Traverse the list of pending bios and re-queue them */
2083 if (bio_segments(bio
) > segs
) {
2085 * This bio has more segments than what we can
2086 * handle, we have to split it.
2088 pending
= (bio_segments(bio
) + segs
- 1) / segs
;
2089 split_bio
= kzalloc(sizeof(*split_bio
), GFP_NOIO
);
2090 BUG_ON(split_bio
== NULL
);
2091 atomic_set(&split_bio
->pending
, pending
);
2092 split_bio
->bio
= bio
;
2093 for (i
= 0; i
< pending
; i
++) {
2094 offset
= (i
* segs
* XEN_PAGE_SIZE
) >> 9;
2095 size
= min((unsigned int)(segs
* XEN_PAGE_SIZE
) >> 9,
2096 (unsigned int)bio_sectors(bio
) - offset
);
2097 cloned_bio
= bio_clone(bio
, GFP_NOIO
);
2098 BUG_ON(cloned_bio
== NULL
);
2099 bio_trim(cloned_bio
, offset
, size
);
2100 cloned_bio
->bi_private
= split_bio
;
2101 cloned_bio
->bi_end_io
= split_bio_end
;
2102 submit_bio(cloned_bio
->bi_rw
, cloned_bio
);
2105 * Now we have to wait for all those smaller bios to
2106 * end, so we can also end the "parent" bio.
2110 /* We don't need to split this bio */
2111 submit_bio(bio
->bi_rw
, bio
);
2118 * We are reconnecting to the backend, due to a suspend/resume, or a backend
2119 * driver restart. We tear down our blkif structure and recreate it, but
2120 * leave the device-layer structures intact so that this is transparent to the
2121 * rest of the kernel.
2123 static int blkfront_resume(struct xenbus_device
*dev
)
2125 struct blkfront_info
*info
= dev_get_drvdata(&dev
->dev
);
2128 dev_dbg(&dev
->dev
, "blkfront_resume: %s\n", dev
->nodename
);
2130 blkif_free(info
, info
->connected
== BLKIF_STATE_CONNECTED
);
2132 err
= talk_to_blkback(dev
, info
);
2135 * We have to wait for the backend to switch to
2136 * connected state, since we want to read which
2137 * features it supports.
2143 static void blkfront_closing(struct blkfront_info
*info
)
2145 struct xenbus_device
*xbdev
= info
->xbdev
;
2146 struct block_device
*bdev
= NULL
;
2148 mutex_lock(&info
->mutex
);
2150 if (xbdev
->state
== XenbusStateClosing
) {
2151 mutex_unlock(&info
->mutex
);
2156 bdev
= bdget_disk(info
->gd
, 0);
2158 mutex_unlock(&info
->mutex
);
2161 xenbus_frontend_closed(xbdev
);
2165 mutex_lock(&bdev
->bd_mutex
);
2167 if (bdev
->bd_openers
) {
2168 xenbus_dev_error(xbdev
, -EBUSY
,
2169 "Device in use; refusing to close");
2170 xenbus_switch_state(xbdev
, XenbusStateClosing
);
2172 xlvbd_release_gendisk(info
);
2173 xenbus_frontend_closed(xbdev
);
2176 mutex_unlock(&bdev
->bd_mutex
);
2180 static void blkfront_setup_discard(struct blkfront_info
*info
)
2183 unsigned int discard_granularity
;
2184 unsigned int discard_alignment
;
2185 unsigned int discard_secure
;
2187 info
->feature_discard
= 1;
2188 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2189 "discard-granularity", "%u", &discard_granularity
,
2190 "discard-alignment", "%u", &discard_alignment
,
2193 info
->discard_granularity
= discard_granularity
;
2194 info
->discard_alignment
= discard_alignment
;
2196 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2197 "discard-secure", "%d", &discard_secure
,
2200 info
->feature_secdiscard
= !!discard_secure
;
2203 static int blkfront_setup_indirect(struct blkfront_ring_info
*rinfo
)
2205 unsigned int psegs
, grants
;
2207 struct blkfront_info
*info
= rinfo
->dev_info
;
2209 if (info
->max_indirect_segments
== 0) {
2211 grants
= BLKIF_MAX_SEGMENTS_PER_REQUEST
;
2214 * When an extra req is required, the maximum
2215 * grants supported is related to the size of the
2216 * Linux block segment.
2218 grants
= GRANTS_PER_PSEG
;
2222 grants
= info
->max_indirect_segments
;
2223 psegs
= grants
/ GRANTS_PER_PSEG
;
2225 err
= fill_grant_buffer(rinfo
,
2226 (grants
+ INDIRECT_GREFS(grants
)) * BLK_RING_SIZE(info
));
2230 if (!info
->feature_persistent
&& info
->max_indirect_segments
) {
2232 * We are using indirect descriptors but not persistent
2233 * grants, we need to allocate a set of pages that can be
2234 * used for mapping indirect grefs
2236 int num
= INDIRECT_GREFS(grants
) * BLK_RING_SIZE(info
);
2238 BUG_ON(!list_empty(&rinfo
->indirect_pages
));
2239 for (i
= 0; i
< num
; i
++) {
2240 struct page
*indirect_page
= alloc_page(GFP_NOIO
);
2243 list_add(&indirect_page
->lru
, &rinfo
->indirect_pages
);
2247 for (i
= 0; i
< BLK_RING_SIZE(info
); i
++) {
2248 rinfo
->shadow
[i
].grants_used
= kzalloc(
2249 sizeof(rinfo
->shadow
[i
].grants_used
[0]) * grants
,
2251 rinfo
->shadow
[i
].sg
= kzalloc(sizeof(rinfo
->shadow
[i
].sg
[0]) * psegs
, GFP_NOIO
);
2252 if (info
->max_indirect_segments
)
2253 rinfo
->shadow
[i
].indirect_grants
= kzalloc(
2254 sizeof(rinfo
->shadow
[i
].indirect_grants
[0]) *
2255 INDIRECT_GREFS(grants
),
2257 if ((rinfo
->shadow
[i
].grants_used
== NULL
) ||
2258 (rinfo
->shadow
[i
].sg
== NULL
) ||
2259 (info
->max_indirect_segments
&&
2260 (rinfo
->shadow
[i
].indirect_grants
== NULL
)))
2262 sg_init_table(rinfo
->shadow
[i
].sg
, psegs
);
2269 for (i
= 0; i
< BLK_RING_SIZE(info
); i
++) {
2270 kfree(rinfo
->shadow
[i
].grants_used
);
2271 rinfo
->shadow
[i
].grants_used
= NULL
;
2272 kfree(rinfo
->shadow
[i
].sg
);
2273 rinfo
->shadow
[i
].sg
= NULL
;
2274 kfree(rinfo
->shadow
[i
].indirect_grants
);
2275 rinfo
->shadow
[i
].indirect_grants
= NULL
;
2277 if (!list_empty(&rinfo
->indirect_pages
)) {
2278 struct page
*indirect_page
, *n
;
2279 list_for_each_entry_safe(indirect_page
, n
, &rinfo
->indirect_pages
, lru
) {
2280 list_del(&indirect_page
->lru
);
2281 __free_page(indirect_page
);
2288 * Gather all backend feature-*
2290 static void blkfront_gather_backend_features(struct blkfront_info
*info
)
2293 int barrier
, flush
, discard
, persistent
;
2294 unsigned int indirect_segments
;
2296 info
->feature_flush
= 0;
2298 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2299 "feature-barrier", "%d", &barrier
,
2303 * If there's no "feature-barrier" defined, then it means
2304 * we're dealing with a very old backend which writes
2305 * synchronously; nothing to do.
2307 * If there are barriers, then we use flush.
2309 if (!err
&& barrier
)
2310 info
->feature_flush
= REQ_FLUSH
| REQ_FUA
;
2312 * And if there is "feature-flush-cache" use that above
2315 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2316 "feature-flush-cache", "%d", &flush
,
2320 info
->feature_flush
= REQ_FLUSH
;
2322 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2323 "feature-discard", "%d", &discard
,
2326 if (!err
&& discard
)
2327 blkfront_setup_discard(info
);
2329 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2330 "feature-persistent", "%u", &persistent
,
2333 info
->feature_persistent
= 0;
2335 info
->feature_persistent
= persistent
;
2337 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2338 "feature-max-indirect-segments", "%u", &indirect_segments
,
2341 info
->max_indirect_segments
= 0;
2343 info
->max_indirect_segments
= min(indirect_segments
,
2344 xen_blkif_max_segments
);
2348 * Invoked when the backend is finally 'ready' (and has told produced
2349 * the details about the physical device - #sectors, size, etc).
2351 static void blkfront_connect(struct blkfront_info
*info
)
2353 unsigned long long sectors
;
2354 unsigned long sector_size
;
2355 unsigned int physical_sector_size
;
2359 switch (info
->connected
) {
2360 case BLKIF_STATE_CONNECTED
:
2362 * Potentially, the back-end may be signalling
2363 * a capacity change; update the capacity.
2365 err
= xenbus_scanf(XBT_NIL
, info
->xbdev
->otherend
,
2366 "sectors", "%Lu", §ors
);
2367 if (XENBUS_EXIST_ERR(err
))
2369 printk(KERN_INFO
"Setting capacity to %Lu\n",
2371 set_capacity(info
->gd
, sectors
);
2372 revalidate_disk(info
->gd
);
2375 case BLKIF_STATE_SUSPENDED
:
2377 * If we are recovering from suspension, we need to wait
2378 * for the backend to announce it's features before
2379 * reconnecting, at least we need to know if the backend
2380 * supports indirect descriptors, and how many.
2382 blkif_recover(info
);
2389 dev_dbg(&info
->xbdev
->dev
, "%s:%s.\n",
2390 __func__
, info
->xbdev
->otherend
);
2392 err
= xenbus_gather(XBT_NIL
, info
->xbdev
->otherend
,
2393 "sectors", "%llu", §ors
,
2394 "info", "%u", &binfo
,
2395 "sector-size", "%lu", §or_size
,
2398 xenbus_dev_fatal(info
->xbdev
, err
,
2399 "reading backend fields at %s",
2400 info
->xbdev
->otherend
);
2405 * physcial-sector-size is a newer field, so old backends may not
2406 * provide this. Assume physical sector size to be the same as
2407 * sector_size in that case.
2409 err
= xenbus_scanf(XBT_NIL
, info
->xbdev
->otherend
,
2410 "physical-sector-size", "%u", &physical_sector_size
);
2412 physical_sector_size
= sector_size
;
2414 blkfront_gather_backend_features(info
);
2415 for (i
= 0; i
< info
->nr_rings
; i
++) {
2416 err
= blkfront_setup_indirect(&info
->rinfo
[i
]);
2418 xenbus_dev_fatal(info
->xbdev
, err
, "setup_indirect at %s",
2419 info
->xbdev
->otherend
);
2420 blkif_free(info
, 0);
2425 err
= xlvbd_alloc_gendisk(sectors
, info
, binfo
, sector_size
,
2426 physical_sector_size
);
2428 xenbus_dev_fatal(info
->xbdev
, err
, "xlvbd_add at %s",
2429 info
->xbdev
->otherend
);
2433 xenbus_switch_state(info
->xbdev
, XenbusStateConnected
);
2435 /* Kick pending requests. */
2436 info
->connected
= BLKIF_STATE_CONNECTED
;
2437 for (i
= 0; i
< info
->nr_rings
; i
++)
2438 kick_pending_request_queues(&info
->rinfo
[i
]);
2446 * Callback received when the backend's state changes.
2448 static void blkback_changed(struct xenbus_device
*dev
,
2449 enum xenbus_state backend_state
)
2451 struct blkfront_info
*info
= dev_get_drvdata(&dev
->dev
);
2453 dev_dbg(&dev
->dev
, "blkfront:blkback_changed to state %d.\n", backend_state
);
2455 switch (backend_state
) {
2456 case XenbusStateInitWait
:
2457 if (dev
->state
!= XenbusStateInitialising
)
2459 if (talk_to_blkback(dev
, info
))
2461 case XenbusStateInitialising
:
2462 case XenbusStateInitialised
:
2463 case XenbusStateReconfiguring
:
2464 case XenbusStateReconfigured
:
2465 case XenbusStateUnknown
:
2468 case XenbusStateConnected
:
2469 if (dev
->state
!= XenbusStateInitialised
) {
2470 if (talk_to_blkback(dev
, info
))
2473 blkfront_connect(info
);
2476 case XenbusStateClosed
:
2477 if (dev
->state
== XenbusStateClosed
)
2479 /* Missed the backend's Closing state -- fallthrough */
2480 case XenbusStateClosing
:
2482 blkfront_closing(info
);
2487 static int blkfront_remove(struct xenbus_device
*xbdev
)
2489 struct blkfront_info
*info
= dev_get_drvdata(&xbdev
->dev
);
2490 struct block_device
*bdev
= NULL
;
2491 struct gendisk
*disk
;
2493 dev_dbg(&xbdev
->dev
, "%s removed", xbdev
->nodename
);
2495 blkif_free(info
, 0);
2497 mutex_lock(&info
->mutex
);
2501 bdev
= bdget_disk(disk
, 0);
2504 mutex_unlock(&info
->mutex
);
2512 * The xbdev was removed before we reached the Closed
2513 * state. See if it's safe to remove the disk. If the bdev
2514 * isn't closed yet, we let release take care of it.
2517 mutex_lock(&bdev
->bd_mutex
);
2518 info
= disk
->private_data
;
2520 dev_warn(disk_to_dev(disk
),
2521 "%s was hot-unplugged, %d stale handles\n",
2522 xbdev
->nodename
, bdev
->bd_openers
);
2524 if (info
&& !bdev
->bd_openers
) {
2525 xlvbd_release_gendisk(info
);
2526 disk
->private_data
= NULL
;
2530 mutex_unlock(&bdev
->bd_mutex
);
2536 static int blkfront_is_ready(struct xenbus_device
*dev
)
2538 struct blkfront_info
*info
= dev_get_drvdata(&dev
->dev
);
2540 return info
->is_ready
&& info
->xbdev
;
2543 static int blkif_open(struct block_device
*bdev
, fmode_t mode
)
2545 struct gendisk
*disk
= bdev
->bd_disk
;
2546 struct blkfront_info
*info
;
2549 mutex_lock(&blkfront_mutex
);
2551 info
= disk
->private_data
;
2558 mutex_lock(&info
->mutex
);
2561 /* xbdev is closed */
2564 mutex_unlock(&info
->mutex
);
2567 mutex_unlock(&blkfront_mutex
);
2571 static void blkif_release(struct gendisk
*disk
, fmode_t mode
)
2573 struct blkfront_info
*info
= disk
->private_data
;
2574 struct block_device
*bdev
;
2575 struct xenbus_device
*xbdev
;
2577 mutex_lock(&blkfront_mutex
);
2579 bdev
= bdget_disk(disk
, 0);
2582 WARN(1, "Block device %s yanked out from us!\n", disk
->disk_name
);
2585 if (bdev
->bd_openers
)
2589 * Check if we have been instructed to close. We will have
2590 * deferred this request, because the bdev was still open.
2593 mutex_lock(&info
->mutex
);
2594 xbdev
= info
->xbdev
;
2596 if (xbdev
&& xbdev
->state
== XenbusStateClosing
) {
2597 /* pending switch to state closed */
2598 dev_info(disk_to_dev(bdev
->bd_disk
), "releasing disk\n");
2599 xlvbd_release_gendisk(info
);
2600 xenbus_frontend_closed(info
->xbdev
);
2603 mutex_unlock(&info
->mutex
);
2606 /* sudden device removal */
2607 dev_info(disk_to_dev(bdev
->bd_disk
), "releasing disk\n");
2608 xlvbd_release_gendisk(info
);
2609 disk
->private_data
= NULL
;
2616 mutex_unlock(&blkfront_mutex
);
2619 static const struct block_device_operations xlvbd_block_fops
=
2621 .owner
= THIS_MODULE
,
2623 .release
= blkif_release
,
2624 .getgeo
= blkif_getgeo
,
2625 .ioctl
= blkif_ioctl
,
2629 static const struct xenbus_device_id blkfront_ids
[] = {
2634 static struct xenbus_driver blkfront_driver
= {
2635 .ids
= blkfront_ids
,
2636 .probe
= blkfront_probe
,
2637 .remove
= blkfront_remove
,
2638 .resume
= blkfront_resume
,
2639 .otherend_changed
= blkback_changed
,
2640 .is_ready
= blkfront_is_ready
,
2643 static int __init
xlblk_init(void)
2646 int nr_cpus
= num_online_cpus();
2651 if (xen_blkif_max_ring_order
> XENBUS_MAX_RING_GRANT_ORDER
) {
2652 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2653 xen_blkif_max_ring_order
, XENBUS_MAX_RING_GRANT_ORDER
);
2654 xen_blkif_max_ring_order
= XENBUS_MAX_RING_GRANT_ORDER
;
2657 if (xen_blkif_max_queues
> nr_cpus
) {
2658 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2659 xen_blkif_max_queues
, nr_cpus
);
2660 xen_blkif_max_queues
= nr_cpus
;
2663 if (!xen_has_pv_disk_devices())
2666 if (register_blkdev(XENVBD_MAJOR
, DEV_NAME
)) {
2667 printk(KERN_WARNING
"xen_blk: can't get major %d with name %s\n",
2668 XENVBD_MAJOR
, DEV_NAME
);
2672 ret
= xenbus_register_frontend(&blkfront_driver
);
2674 unregister_blkdev(XENVBD_MAJOR
, DEV_NAME
);
2680 module_init(xlblk_init
);
2683 static void __exit
xlblk_exit(void)
2685 xenbus_unregister_driver(&blkfront_driver
);
2686 unregister_blkdev(XENVBD_MAJOR
, DEV_NAME
);
2689 module_exit(xlblk_exit
);
2691 MODULE_DESCRIPTION("Xen virtual block device frontend");
2692 MODULE_LICENSE("GPL");
2693 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR
);
2694 MODULE_ALIAS("xen:vbd");
2695 MODULE_ALIAS("xenblk");