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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-04-18 14:24:23 -0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-04-18 14:30:26 -0400
commitdfc07b13dcacefda6ebdea14584ed8724dc980ef (patch)
treeb4074d80a781146d6577048c237a4502f8fafb9d /drivers/block/xen-blkback
parentd2436eda2e81f1993bfe6349f17f52503bffeff5 (diff)
xen/blkback: Move it from drivers/xen to drivers/block
.. and modify the Makefile and Kconfig files appropriately. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/block/xen-blkback')
-rw-r--r--drivers/block/xen-blkback/Makefile3
-rw-r--r--drivers/block/xen-blkback/blkback.c759
-rw-r--r--drivers/block/xen-blkback/common.h142
-rw-r--r--drivers/block/xen-blkback/interface.c185
-rw-r--r--drivers/block/xen-blkback/vbd.c162
-rw-r--r--drivers/block/xen-blkback/xenbus.c562
6 files changed, 1813 insertions, 0 deletions
diff --git a/drivers/block/xen-blkback/Makefile b/drivers/block/xen-blkback/Makefile
new file mode 100644
index 000000000000..f1ae1ff07a4d
--- /dev/null
+++ b/drivers/block/xen-blkback/Makefile
@@ -0,0 +1,3 @@
1obj-$(CONFIG_XEN_BLKDEV_BACKEND) := xen-blkback.o
2
3xen-blkback-y := blkback.o xenbus.o interface.o vbd.o
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
new file mode 100644
index 000000000000..59a2bae0f35e
--- /dev/null
+++ b/drivers/block/xen-blkback/blkback.c
@@ -0,0 +1,759 @@
1/******************************************************************************
2 *
3 * Back-end of the driver for virtual block devices. This portion of the
4 * driver exports a 'unified' block-device interface that can be accessed
5 * by any operating system that implements a compatible front end. A
6 * reference front-end implementation can be found in:
7 * drivers/block/xen-blkfront.c
8 *
9 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
10 * Copyright (c) 2005, Christopher Clark
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License version 2
14 * as published by the Free Software Foundation; or, when distributed
15 * separately from the Linux kernel or incorporated into other
16 * software packages, subject to the following license:
17 *
18 * Permission is hereby granted, free of charge, to any person obtaining a copy
19 * of this source file (the "Software"), to deal in the Software without
20 * restriction, including without limitation the rights to use, copy, modify,
21 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
22 * and to permit persons to whom the Software is furnished to do so, subject to
23 * the following conditions:
24 *
25 * The above copyright notice and this permission notice shall be included in
26 * all copies or substantial portions of the Software.
27 *
28 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
29 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
30 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
31 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
32 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
33 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
34 * IN THE SOFTWARE.
35 */
36
37#include <linux/spinlock.h>
38#include <linux/kthread.h>
39#include <linux/list.h>
40#include <linux/delay.h>
41#include <linux/freezer.h>
42
43#include <xen/events.h>
44#include <xen/page.h>
45#include <asm/xen/hypervisor.h>
46#include <asm/xen/hypercall.h>
47#include "common.h"
48
49#define WRITE_BARRIER (REQ_WRITE | REQ_FLUSH | REQ_FUA)
50
51/*
52 * These are rather arbitrary. They are fairly large because adjacent requests
53 * pulled from a communication ring are quite likely to end up being part of
54 * the same scatter/gather request at the disc.
55 *
56 * ** TRY INCREASING 'blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW **
57 *
58 * This will increase the chances of being able to write whole tracks.
59 * 64 should be enough to keep us competitive with Linux.
60 */
61static int blkif_reqs = 64;
62module_param_named(reqs, blkif_reqs, int, 0);
63MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate");
64
65/* Run-time switchable: /sys/module/blkback/parameters/ */
66static unsigned int log_stats;
67static unsigned int debug_lvl;
68module_param(log_stats, int, 0644);
69module_param(debug_lvl, int, 0644);
70
71/*
72 * Each outstanding request that we've passed to the lower device layers has a
73 * 'pending_req' allocated to it. Each buffer_head that completes decrements
74 * the pendcnt towards zero. When it hits zero, the specified domain has a
75 * response queued for it, with the saved 'id' passed back.
76 */
77struct pending_req {
78 struct blkif_st *blkif;
79 u64 id;
80 int nr_pages;
81 atomic_t pendcnt;
82 unsigned short operation;
83 int status;
84 struct list_head free_list;
85};
86
87#define BLKBACK_INVALID_HANDLE (~0)
88
89struct xen_blkbk {
90 struct pending_req *pending_reqs;
91 /* List of all 'pending_req' available */
92 struct list_head pending_free;
93 /* And its spinlock. */
94 spinlock_t pending_free_lock;
95 wait_queue_head_t pending_free_wq;
96 /* The list of all pages that are available. */
97 struct page **pending_pages;
98 /* And the grant handles that are available. */
99 grant_handle_t *pending_grant_handles;
100};
101
102static struct xen_blkbk *blkbk;
103
104/*
105 * Little helpful macro to figure out the index and virtual address of the
106 * pending_pages[..]. For each 'pending_req' we have have up to
107 * BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through
108 * 10 and would index in the pending_pages[..]. */
109static inline int vaddr_pagenr(struct pending_req *req, int seg)
110{
111 return (req - blkbk->pending_reqs) *
112 BLKIF_MAX_SEGMENTS_PER_REQUEST + seg;
113}
114
115#define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)]
116
117static inline unsigned long vaddr(struct pending_req *req, int seg)
118{
119 unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg));
120 return (unsigned long)pfn_to_kaddr(pfn);
121}
122
123#define pending_handle(_req, _seg) \
124 (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)])
125
126
127static int do_block_io_op(struct blkif_st *blkif);
128static void dispatch_rw_block_io(struct blkif_st *blkif,
129 struct blkif_request *req,
130 struct pending_req *pending_req);
131static void make_response(struct blkif_st *blkif, u64 id,
132 unsigned short op, int st);
133
134/*
135 * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
136 */
137static struct pending_req *alloc_req(void)
138{
139 struct pending_req *req = NULL;
140 unsigned long flags;
141
142 spin_lock_irqsave(&blkbk->pending_free_lock, flags);
143 if (!list_empty(&blkbk->pending_free)) {
144 req = list_entry(blkbk->pending_free.next, struct pending_req,
145 free_list);
146 list_del(&req->free_list);
147 }
148 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
149 return req;
150}
151
152/*
153 * Return the 'pending_req' structure back to the freepool. We also
154 * wake up the thread if it was waiting for a free page.
155 */
156static void free_req(struct pending_req *req)
157{
158 unsigned long flags;
159 int was_empty;
160
161 spin_lock_irqsave(&blkbk->pending_free_lock, flags);
162 was_empty = list_empty(&blkbk->pending_free);
163 list_add(&req->free_list, &blkbk->pending_free);
164 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
165 if (was_empty)
166 wake_up(&blkbk->pending_free_wq);
167}
168
169/*
170 * Notification from the guest OS.
171 */
172static void blkif_notify_work(struct blkif_st *blkif)
173{
174 blkif->waiting_reqs = 1;
175 wake_up(&blkif->wq);
176}
177
178irqreturn_t blkif_be_int(int irq, void *dev_id)
179{
180 blkif_notify_work(dev_id);
181 return IRQ_HANDLED;
182}
183
184/*
185 * SCHEDULER FUNCTIONS
186 */
187
188static void print_stats(struct blkif_st *blkif)
189{
190 printk(KERN_DEBUG "%s: oo %3d | rd %4d | wr %4d | br %4d\n",
191 current->comm, blkif->st_oo_req,
192 blkif->st_rd_req, blkif->st_wr_req, blkif->st_br_req);
193 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
194 blkif->st_rd_req = 0;
195 blkif->st_wr_req = 0;
196 blkif->st_oo_req = 0;
197}
198
199int blkif_schedule(void *arg)
200{
201 struct blkif_st *blkif = arg;
202 struct vbd *vbd = &blkif->vbd;
203
204 blkif_get(blkif);
205
206 if (debug_lvl)
207 printk(KERN_DEBUG "%s: started\n", current->comm);
208
209 while (!kthread_should_stop()) {
210 if (try_to_freeze())
211 continue;
212 if (unlikely(vbd->size != vbd_size(vbd)))
213 vbd_resize(blkif);
214
215 wait_event_interruptible(
216 blkif->wq,
217 blkif->waiting_reqs || kthread_should_stop());
218 wait_event_interruptible(
219 blkbk->pending_free_wq,
220 !list_empty(&blkbk->pending_free) ||
221 kthread_should_stop());
222
223 blkif->waiting_reqs = 0;
224 smp_mb(); /* clear flag *before* checking for work */
225
226 if (do_block_io_op(blkif))
227 blkif->waiting_reqs = 1;
228
229 if (log_stats && time_after(jiffies, blkif->st_print))
230 print_stats(blkif);
231 }
232
233 if (log_stats)
234 print_stats(blkif);
235 if (debug_lvl)
236 printk(KERN_DEBUG "%s: exiting\n", current->comm);
237
238 blkif->xenblkd = NULL;
239 blkif_put(blkif);
240
241 return 0;
242}
243
244struct seg_buf {
245 unsigned long buf;
246 unsigned int nsec;
247};
248/*
249 * Unmap the grant references, and also remove the M2P over-rides
250 * used in the 'pending_req'.
251*/
252static void xen_blkbk_unmap(struct pending_req *req)
253{
254 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
255 unsigned int i, invcount = 0;
256 grant_handle_t handle;
257 int ret;
258
259 for (i = 0; i < req->nr_pages; i++) {
260 handle = pending_handle(req, i);
261 if (handle == BLKBACK_INVALID_HANDLE)
262 continue;
263 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
264 GNTMAP_host_map, handle);
265 pending_handle(req, i) = BLKBACK_INVALID_HANDLE;
266 invcount++;
267 }
268
269 ret = HYPERVISOR_grant_table_op(
270 GNTTABOP_unmap_grant_ref, unmap, invcount);
271 BUG_ON(ret);
272 /* Note, we use invcount, so nr->pages, so we can't index
273 * using vaddr(req, i).
274 */
275 for (i = 0; i < invcount; i++) {
276 ret = m2p_remove_override(
277 virt_to_page(unmap[i].host_addr), false);
278 if (ret) {
279 printk(KERN_ALERT "Failed to remove M2P override for " \
280 "%lx\n", (unsigned long)unmap[i].host_addr);
281 continue;
282 }
283 }
284}
285static int xen_blkbk_map(struct blkif_request *req, struct pending_req *pending_req,
286 struct seg_buf seg[])
287{
288 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
289 int i;
290 int nseg = req->nr_segments;
291 int ret = 0;
292 /* Fill out preq.nr_sects with proper amount of sectors, and setup
293 * assign map[..] with the PFN of the page in our domain with the
294 * corresponding grant reference for each page.
295 */
296 for (i = 0; i < nseg; i++) {
297 uint32_t flags;
298
299 flags = GNTMAP_host_map;
300 if (pending_req->operation != BLKIF_OP_READ)
301 flags |= GNTMAP_readonly;
302 gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags,
303 req->u.rw.seg[i].gref, pending_req->blkif->domid);
304 }
305
306 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg);
307 BUG_ON(ret);
308
309 /* Now swizzel the MFN in our domain with the MFN from the other domain
310 * so that when we access vaddr(pending_req,i) it has the contents of
311 * the page from the other domain.
312 */
313 for (i = 0; i < nseg; i++) {
314 if (unlikely(map[i].status != 0)) {
315 DPRINTK("invalid buffer -- could not remap it\n");
316 map[i].handle = BLKBACK_INVALID_HANDLE;
317 ret |= 1;
318 }
319
320 pending_handle(pending_req, i) = map[i].handle;
321
322 if (ret)
323 continue;
324
325 ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr),
326 blkbk->pending_page(pending_req, i), false);
327 if (ret) {
328 printk(KERN_ALERT "Failed to install M2P override for"\
329 " %lx (ret: %d)\n", (unsigned long)
330 map[i].dev_bus_addr, ret);
331 /* We could switch over to GNTTABOP_copy */
332 continue;
333 }
334
335 seg[i].buf = map[i].dev_bus_addr |
336 (req->u.rw.seg[i].first_sect << 9);
337 }
338 return ret;
339}
340
341/*
342 * Completion callback on the bio's. Called as bh->b_end_io()
343 */
344
345static void __end_block_io_op(struct pending_req *pending_req, int error)
346{
347 /* An error fails the entire request. */
348 if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
349 (error == -EOPNOTSUPP)) {
350 DPRINTK("blkback: write barrier op failed, not supported\n");
351 blkback_barrier(XBT_NIL, pending_req->blkif->be, 0);
352 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
353 } else if (error) {
354 DPRINTK("Buffer not up-to-date at end of operation, "
355 "error=%d\n", error);
356 pending_req->status = BLKIF_RSP_ERROR;
357 }
358
359 /* If all of the bio's have completed it is time to unmap
360 * the grant references associated with 'request' and provide
361 * the proper response on the ring.
362 */
363 if (atomic_dec_and_test(&pending_req->pendcnt)) {
364 xen_blkbk_unmap(pending_req);
365 make_response(pending_req->blkif, pending_req->id,
366 pending_req->operation, pending_req->status);
367 blkif_put(pending_req->blkif);
368 free_req(pending_req);
369 }
370}
371
372/*
373 * bio callback.
374 */
375static void end_block_io_op(struct bio *bio, int error)
376{
377 __end_block_io_op(bio->bi_private, error);
378 bio_put(bio);
379}
380
381
382
383/*
384 * Function to copy the from the ring buffer the 'struct blkif_request'
385 * (which has the sectors we want, number of them, grant references, etc),
386 * and transmute it to the block API to hand it over to the proper block disk.
387 */
388static int do_block_io_op(struct blkif_st *blkif)
389{
390 union blkif_back_rings *blk_rings = &blkif->blk_rings;
391 struct blkif_request req;
392 struct pending_req *pending_req;
393 RING_IDX rc, rp;
394 int more_to_do = 0;
395
396 rc = blk_rings->common.req_cons;
397 rp = blk_rings->common.sring->req_prod;
398 rmb(); /* Ensure we see queued requests up to 'rp'. */
399
400 while (rc != rp) {
401
402 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
403 break;
404
405 if (kthread_should_stop()) {
406 more_to_do = 1;
407 break;
408 }
409
410 pending_req = alloc_req();
411 if (NULL == pending_req) {
412 blkif->st_oo_req++;
413 more_to_do = 1;
414 break;
415 }
416
417 switch (blkif->blk_protocol) {
418 case BLKIF_PROTOCOL_NATIVE:
419 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
420 break;
421 case BLKIF_PROTOCOL_X86_32:
422 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
423 break;
424 case BLKIF_PROTOCOL_X86_64:
425 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
426 break;
427 default:
428 BUG();
429 }
430 blk_rings->common.req_cons = ++rc; /* before make_response() */
431
432 /* Apply all sanity checks to /private copy/ of request. */
433 barrier();
434
435 switch (req.operation) {
436 case BLKIF_OP_READ:
437 blkif->st_rd_req++;
438 dispatch_rw_block_io(blkif, &req, pending_req);
439 break;
440 case BLKIF_OP_WRITE_BARRIER:
441 blkif->st_br_req++;
442 /* fall through */
443 case BLKIF_OP_WRITE:
444 blkif->st_wr_req++;
445 dispatch_rw_block_io(blkif, &req, pending_req);
446 break;
447 default:
448 /* A good sign something is wrong: sleep for a while to
449 * avoid excessive CPU consumption by a bad guest. */
450 msleep(1);
451 DPRINTK("error: unknown block io operation [%d]\n",
452 req.operation);
453 make_response(blkif, req.id, req.operation,
454 BLKIF_RSP_ERROR);
455 free_req(pending_req);
456 break;
457 }
458
459 /* Yield point for this unbounded loop. */
460 cond_resched();
461 }
462
463 return more_to_do;
464}
465
466/*
467 * Transumation of the 'struct blkif_request' to a proper 'struct bio'
468 * and call the 'submit_bio' to pass it to the underlaying storage.
469 */
470static void dispatch_rw_block_io(struct blkif_st *blkif,
471 struct blkif_request *req,
472 struct pending_req *pending_req)
473{
474 struct phys_req preq;
475 struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
476 unsigned int nseg;
477 struct bio *bio = NULL;
478 struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST];
479 int i, nbio = 0;
480 int operation;
481 struct blk_plug plug;
482
483 switch (req->operation) {
484 case BLKIF_OP_READ:
485 operation = READ;
486 break;
487 case BLKIF_OP_WRITE:
488 operation = WRITE;
489 break;
490 case BLKIF_OP_WRITE_BARRIER:
491 operation = WRITE_BARRIER;
492 break;
493 default:
494 operation = 0; /* make gcc happy */
495 BUG();
496 }
497
498 /* Check that the number of segments is sane. */
499 nseg = req->nr_segments;
500 if (unlikely(nseg == 0 && operation != WRITE_BARRIER) ||
501 unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
502 DPRINTK("Bad number of segments in request (%d)\n", nseg);
503 /* Haven't submitted any bio's yet. */
504 goto fail_response;
505 }
506
507 preq.dev = req->handle;
508 preq.sector_number = req->u.rw.sector_number;
509 preq.nr_sects = 0;
510
511 pending_req->blkif = blkif;
512 pending_req->id = req->id;
513 pending_req->operation = req->operation;
514 pending_req->status = BLKIF_RSP_OKAY;
515 pending_req->nr_pages = nseg;
516
517 for (i = 0; i < nseg; i++) {
518 seg[i].nsec = req->u.rw.seg[i].last_sect -
519 req->u.rw.seg[i].first_sect + 1;
520 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
521 (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect))
522 goto fail_response;
523 preq.nr_sects += seg[i].nsec;
524
525 }
526
527 if (vbd_translate(&preq, blkif, operation) != 0) {
528 DPRINTK("access denied: %s of [%llu,%llu] on dev=%04x\n",
529 operation == READ ? "read" : "write",
530 preq.sector_number,
531 preq.sector_number + preq.nr_sects, preq.dev);
532 goto fail_response;
533 }
534 /* This check _MUST_ be done after vbd_translate as the preq.bdev
535 * is set there. */
536 for (i = 0; i < nseg; i++) {
537 if (((int)preq.sector_number|(int)seg[i].nsec) &
538 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
539 DPRINTK("Misaligned I/O request from domain %d",
540 blkif->domid);
541 goto fail_response;
542 }
543 }
544 /* If we have failed at this point, we need to undo the M2P override,
545 * set gnttab_set_unmap_op on all of the grant references and perform
546 * the hypercall to unmap the grants - that is all done in
547 * xen_blkbk_unmap.
548 */
549 if (xen_blkbk_map(req, pending_req, seg))
550 goto fail_flush;
551
552 /* This corresponding blkif_put is done in __end_block_io_op */
553 blkif_get(blkif);
554
555 for (i = 0; i < nseg; i++) {
556 while ((bio == NULL) ||
557 (bio_add_page(bio,
558 blkbk->pending_page(pending_req, i),
559 seg[i].nsec << 9,
560 seg[i].buf & ~PAGE_MASK) == 0)) {
561
562 bio = biolist[nbio++] = bio_alloc(GFP_KERNEL, nseg-i);
563 if (unlikely(bio == NULL))
564 goto fail_put_bio;
565
566 bio->bi_bdev = preq.bdev;
567 bio->bi_private = pending_req;
568 bio->bi_end_io = end_block_io_op;
569 bio->bi_sector = preq.sector_number;
570 }
571
572 preq.sector_number += seg[i].nsec;
573 }
574
575 /* This will be hit if the operation was a barrier. */
576 if (!bio) {
577 BUG_ON(operation != WRITE_BARRIER);
578 bio = biolist[nbio++] = bio_alloc(GFP_KERNEL, 0);
579 if (unlikely(bio == NULL))
580 goto fail_put_bio;
581
582 bio->bi_bdev = preq.bdev;
583 bio->bi_private = pending_req;
584 bio->bi_end_io = end_block_io_op;
585 bio->bi_sector = -1;
586 }
587
588
589 /* We set it one so that the last submit_bio does not have to call
590 * atomic_inc.
591 */
592 atomic_set(&pending_req->pendcnt, nbio);
593
594 /* Get a reference count for the disk queue and start sending I/O */
595 blk_start_plug(&plug);
596
597 for (i = 0; i < nbio; i++)
598 submit_bio(operation, biolist[i]);
599
600 blk_finish_plug(&plug);
601 /* Let the I/Os go.. */
602
603 if (operation == READ)
604 blkif->st_rd_sect += preq.nr_sects;
605 else if (operation == WRITE || operation == WRITE_BARRIER)
606 blkif->st_wr_sect += preq.nr_sects;
607
608 return;
609
610 fail_flush:
611 xen_blkbk_unmap(pending_req);
612 fail_response:
613 /* Haven't submitted any bio's yet. */
614 make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR);
615 free_req(pending_req);
616 msleep(1); /* back off a bit */
617 return;
618
619 fail_put_bio:
620 for (i = 0; i < (nbio-1); i++)
621 bio_put(biolist[i]);
622 __end_block_io_op(pending_req, -EINVAL);
623 msleep(1); /* back off a bit */
624 return;
625}
626
627
628
629/*
630 * Put a response on the ring on how the operation fared.
631 */
632static void make_response(struct blkif_st *blkif, u64 id,
633 unsigned short op, int st)
634{
635 struct blkif_response resp;
636 unsigned long flags;
637 union blkif_back_rings *blk_rings = &blkif->blk_rings;
638 int more_to_do = 0;
639 int notify;
640
641 resp.id = id;
642 resp.operation = op;
643 resp.status = st;
644
645 spin_lock_irqsave(&blkif->blk_ring_lock, flags);
646 /* Place on the response ring for the relevant domain. */
647 switch (blkif->blk_protocol) {
648 case BLKIF_PROTOCOL_NATIVE:
649 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
650 &resp, sizeof(resp));
651 break;
652 case BLKIF_PROTOCOL_X86_32:
653 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
654 &resp, sizeof(resp));
655 break;
656 case BLKIF_PROTOCOL_X86_64:
657 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
658 &resp, sizeof(resp));
659 break;
660 default:
661 BUG();
662 }
663 blk_rings->common.rsp_prod_pvt++;
664 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
665 if (blk_rings->common.rsp_prod_pvt == blk_rings->common.req_cons) {
666 /*
667 * Tail check for pending requests. Allows frontend to avoid
668 * notifications if requests are already in flight (lower
669 * overheads and promotes batching).
670 */
671 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
672
673 } else if (RING_HAS_UNCONSUMED_REQUESTS(&blk_rings->common)) {
674 more_to_do = 1;
675 }
676
677 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
678
679 if (more_to_do)
680 blkif_notify_work(blkif);
681 if (notify)
682 notify_remote_via_irq(blkif->irq);
683}
684
685static int __init blkif_init(void)
686{
687 int i, mmap_pages;
688 int rc = 0;
689
690 if (!xen_pv_domain())
691 return -ENODEV;
692
693 blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL);
694 if (!blkbk) {
695 printk(KERN_ALERT "%s: out of memory!\n", __func__);
696 return -ENOMEM;
697 }
698
699 mmap_pages = blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST;
700
701 blkbk->pending_reqs = kmalloc(sizeof(blkbk->pending_reqs[0]) *
702 blkif_reqs, GFP_KERNEL);
703 blkbk->pending_grant_handles = kzalloc(sizeof(blkbk->pending_grant_handles[0]) *
704 mmap_pages, GFP_KERNEL);
705 blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) *
706 mmap_pages, GFP_KERNEL);
707
708 if (!blkbk->pending_reqs || !blkbk->pending_grant_handles ||
709 !blkbk->pending_pages) {
710 rc = -ENOMEM;
711 goto out_of_memory;
712 }
713
714 for (i = 0; i < mmap_pages; i++) {
715 blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE;
716 blkbk->pending_pages[i] = alloc_page(GFP_KERNEL);
717 if (blkbk->pending_pages[i] == NULL) {
718 rc = -ENOMEM;
719 goto out_of_memory;
720 }
721 }
722 rc = blkif_interface_init();
723 if (rc)
724 goto failed_init;
725
726 memset(blkbk->pending_reqs, 0, sizeof(blkbk->pending_reqs));
727
728 INIT_LIST_HEAD(&blkbk->pending_free);
729 spin_lock_init(&blkbk->pending_free_lock);
730 init_waitqueue_head(&blkbk->pending_free_wq);
731
732 for (i = 0; i < blkif_reqs; i++)
733 list_add_tail(&blkbk->pending_reqs[i].free_list,
734 &blkbk->pending_free);
735
736 rc = blkif_xenbus_init();
737 if (rc)
738 goto failed_init;
739
740 return 0;
741
742 out_of_memory:
743 printk(KERN_ERR "%s: out of memory\n", __func__);
744 failed_init:
745 kfree(blkbk->pending_reqs);
746 kfree(blkbk->pending_grant_handles);
747 for (i = 0; i < mmap_pages; i++) {
748 if (blkbk->pending_pages[i])
749 __free_page(blkbk->pending_pages[i]);
750 }
751 kfree(blkbk->pending_pages);
752 kfree(blkbk);
753 blkbk = NULL;
754 return rc;
755}
756
757module_init(blkif_init);
758
759MODULE_LICENSE("Dual BSD/GPL");
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
new file mode 100644
index 000000000000..6257c1106591
--- /dev/null
+++ b/drivers/block/xen-blkback/common.h
@@ -0,0 +1,142 @@
1/*
2 * This program is free software; you can redistribute it and/or
3 * modify it under the terms of the GNU General Public License version 2
4 * as published by the Free Software Foundation; or, when distributed
5 * separately from the Linux kernel or incorporated into other
6 * software packages, subject to the following license:
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this source file (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use, copy, modify,
11 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
12 * and to permit persons to whom the Software is furnished to do so, subject to
13 * the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * IN THE SOFTWARE.
25 */
26
27#ifndef __BLKIF__BACKEND__COMMON_H__
28#define __BLKIF__BACKEND__COMMON_H__
29
30#include <linux/version.h>
31#include <linux/module.h>
32#include <linux/interrupt.h>
33#include <linux/slab.h>
34#include <linux/blkdev.h>
35#include <linux/vmalloc.h>
36#include <linux/wait.h>
37#include <linux/io.h>
38#include <asm/setup.h>
39#include <asm/pgalloc.h>
40#include <asm/hypervisor.h>
41#include <xen/blkif.h>
42#include <xen/grant_table.h>
43#include <xen/xenbus.h>
44
45#define DPRINTK(_f, _a...) \
46 pr_debug("(file=%s, line=%d) " _f, \
47 __FILE__ , __LINE__ , ## _a)
48
49struct vbd {
50 blkif_vdev_t handle; /* what the domain refers to this vbd as */
51 unsigned char readonly; /* Non-zero -> read-only */
52 unsigned char type; /* VDISK_xxx */
53 u32 pdevice; /* phys device that this vbd maps to */
54 struct block_device *bdev;
55 sector_t size; /* Cached size parameter */
56};
57
58struct backend_info;
59
60struct blkif_st {
61 /* Unique identifier for this interface. */
62 domid_t domid;
63 unsigned int handle;
64 /* Physical parameters of the comms window. */
65 unsigned int irq;
66 /* Comms information. */
67 enum blkif_protocol blk_protocol;
68 union blkif_back_rings blk_rings;
69 struct vm_struct *blk_ring_area;
70 /* The VBD attached to this interface. */
71 struct vbd vbd;
72 /* Back pointer to the backend_info. */
73 struct backend_info *be;
74 /* Private fields. */
75 spinlock_t blk_ring_lock;
76 atomic_t refcnt;
77
78 wait_queue_head_t wq;
79 /* One thread per one blkif. */
80 struct task_struct *xenblkd;
81 unsigned int waiting_reqs;
82
83 /* statistics */
84 unsigned long st_print;
85 int st_rd_req;
86 int st_wr_req;
87 int st_oo_req;
88 int st_br_req;
89 int st_rd_sect;
90 int st_wr_sect;
91
92 wait_queue_head_t waiting_to_free;
93
94 grant_handle_t shmem_handle;
95 grant_ref_t shmem_ref;
96};
97
98struct blkif_st *blkif_alloc(domid_t domid);
99void blkif_disconnect(struct blkif_st *blkif);
100void blkif_free(struct blkif_st *blkif);
101int blkif_map(struct blkif_st *blkif, unsigned long shared_page,
102 unsigned int evtchn);
103void vbd_resize(struct blkif_st *blkif);
104
105#define blkif_get(_b) (atomic_inc(&(_b)->refcnt))
106#define blkif_put(_b) \
107 do { \
108 if (atomic_dec_and_test(&(_b)->refcnt)) \
109 wake_up(&(_b)->waiting_to_free);\
110 } while (0)
111
112/* Create a vbd. */
113int vbd_create(struct blkif_st *blkif, blkif_vdev_t vdevice, unsigned major,
114 unsigned minor, int readonly, int cdrom);
115void vbd_free(struct vbd *vbd);
116
117unsigned long long vbd_size(struct vbd *vbd);
118unsigned int vbd_info(struct vbd *vbd);
119unsigned long vbd_secsize(struct vbd *vbd);
120
121struct phys_req {
122 unsigned short dev;
123 unsigned short nr_sects;
124 struct block_device *bdev;
125 blkif_sector_t sector_number;
126};
127
128int vbd_translate(struct phys_req *req, struct blkif_st *blkif, int operation);
129
130int blkif_interface_init(void);
131
132int blkif_xenbus_init(void);
133
134irqreturn_t blkif_be_int(int irq, void *dev_id);
135int blkif_schedule(void *arg);
136
137int blkback_barrier(struct xenbus_transaction xbt,
138 struct backend_info *be, int state);
139
140struct xenbus_device *blkback_xenbus(struct backend_info *be);
141
142#endif /* __BLKIF__BACKEND__COMMON_H__ */
diff --git a/drivers/block/xen-blkback/interface.c b/drivers/block/xen-blkback/interface.c
new file mode 100644
index 000000000000..163aed41e825
--- /dev/null
+++ b/drivers/block/xen-blkback/interface.c
@@ -0,0 +1,185 @@
1/******************************************************************************
2 * Block-device interface management.
3 *
4 * Copyright (c) 2004, Keir Fraser
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version 2
8 * as published by the Free Software Foundation; or, when distributed
9 * separately from the Linux kernel or incorporated into other
10 * software packages, subject to the following license:
11 *
12 * Permission is hereby granted, free of charge, to any person obtaining a copy
13 * of this source file (the "Software"), to deal in the Software without
14 * restriction, including without limitation the rights to use, copy, modify,
15 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
16 * and to permit persons to whom the Software is furnished to do so, subject to
17 * the following conditions:
18 *
19 * The above copyright notice and this permission notice shall be included in
20 * all copies or substantial portions of the Software.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
28 * IN THE SOFTWARE.
29 */
30
31#include "common.h"
32#include <xen/events.h>
33#include <xen/grant_table.h>
34#include <linux/kthread.h>
35
36static struct kmem_cache *blkif_cachep;
37
38struct blkif_st *blkif_alloc(domid_t domid)
39{
40 struct blkif_st *blkif;
41
42 blkif = kmem_cache_alloc(blkif_cachep, GFP_KERNEL);
43 if (!blkif)
44 return ERR_PTR(-ENOMEM);
45
46 memset(blkif, 0, sizeof(*blkif));
47 blkif->domid = domid;
48 spin_lock_init(&blkif->blk_ring_lock);
49 atomic_set(&blkif->refcnt, 1);
50 init_waitqueue_head(&blkif->wq);
51 blkif->st_print = jiffies;
52 init_waitqueue_head(&blkif->waiting_to_free);
53
54 return blkif;
55}
56
57static int map_frontend_page(struct blkif_st *blkif, unsigned long shared_page)
58{
59 struct gnttab_map_grant_ref op;
60
61 gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
62 GNTMAP_host_map, shared_page, blkif->domid);
63
64 if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
65 BUG();
66
67 if (op.status) {
68 DPRINTK(" Grant table operation failure !\n");
69 return op.status;
70 }
71
72 blkif->shmem_ref = shared_page;
73 blkif->shmem_handle = op.handle;
74
75 return 0;
76}
77
78static void unmap_frontend_page(struct blkif_st *blkif)
79{
80 struct gnttab_unmap_grant_ref op;
81
82 gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
83 GNTMAP_host_map, blkif->shmem_handle);
84
85 if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
86 BUG();
87}
88
89int blkif_map(struct blkif_st *blkif, unsigned long shared_page,
90 unsigned int evtchn)
91{
92 int err;
93
94 /* Already connected through? */
95 if (blkif->irq)
96 return 0;
97
98 blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE);
99 if (!blkif->blk_ring_area)
100 return -ENOMEM;
101
102 err = map_frontend_page(blkif, shared_page);
103 if (err) {
104 free_vm_area(blkif->blk_ring_area);
105 return err;
106 }
107
108 switch (blkif->blk_protocol) {
109 case BLKIF_PROTOCOL_NATIVE:
110 {
111 struct blkif_sring *sring;
112 sring = (struct blkif_sring *)blkif->blk_ring_area->addr;
113 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
114 break;
115 }
116 case BLKIF_PROTOCOL_X86_32:
117 {
118 struct blkif_x86_32_sring *sring_x86_32;
119 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring_area->addr;
120 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
121 break;
122 }
123 case BLKIF_PROTOCOL_X86_64:
124 {
125 struct blkif_x86_64_sring *sring_x86_64;
126 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;
127 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
128 break;
129 }
130 default:
131 BUG();
132 }
133
134 err = bind_interdomain_evtchn_to_irqhandler(
135 blkif->domid, evtchn, blkif_be_int, 0, "blkif-backend", blkif);
136 if (err < 0) {
137 unmap_frontend_page(blkif);
138 free_vm_area(blkif->blk_ring_area);
139 blkif->blk_rings.common.sring = NULL;
140 return err;
141 }
142 blkif->irq = err;
143
144 return 0;
145}
146
147void blkif_disconnect(struct blkif_st *blkif)
148{
149 if (blkif->xenblkd) {
150 kthread_stop(blkif->xenblkd);
151 blkif->xenblkd = NULL;
152 }
153
154 atomic_dec(&blkif->refcnt);
155 wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
156 atomic_inc(&blkif->refcnt);
157
158 if (blkif->irq) {
159 unbind_from_irqhandler(blkif->irq, blkif);
160 blkif->irq = 0;
161 }
162
163 if (blkif->blk_rings.common.sring) {
164 unmap_frontend_page(blkif);
165 free_vm_area(blkif->blk_ring_area);
166 blkif->blk_rings.common.sring = NULL;
167 }
168}
169
170void blkif_free(struct blkif_st *blkif)
171{
172 if (!atomic_dec_and_test(&blkif->refcnt))
173 BUG();
174 kmem_cache_free(blkif_cachep, blkif);
175}
176
177int __init blkif_interface_init(void)
178{
179 blkif_cachep = kmem_cache_create("blkif_cache", sizeof(struct blkif_st),
180 0, 0, NULL);
181 if (!blkif_cachep)
182 return -ENOMEM;
183
184 return 0;
185}
diff --git a/drivers/block/xen-blkback/vbd.c b/drivers/block/xen-blkback/vbd.c
new file mode 100644
index 000000000000..d0ff4cf91a34
--- /dev/null
+++ b/drivers/block/xen-blkback/vbd.c
@@ -0,0 +1,162 @@
1/******************************************************************************
2 * Routines for managing virtual block devices (VBDs).
3 *
4 * Copyright (c) 2003-2005, Keir Fraser & Steve Hand
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version 2
8 * as published by the Free Software Foundation; or, when distributed
9 * separately from the Linux kernel or incorporated into other
10 * software packages, subject to the following license:
11 *
12 * Permission is hereby granted, free of charge, to any person obtaining a copy
13 * of this source file (the "Software"), to deal in the Software without
14 * restriction, including without limitation the rights to use, copy, modify,
15 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
16 * and to permit persons to whom the Software is furnished to do so, subject to
17 * the following conditions:
18 *
19 * The above copyright notice and this permission notice shall be included in
20 * all copies or substantial portions of the Software.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
28 * IN THE SOFTWARE.
29 */
30
31#include "common.h"
32
33#define vbd_sz(_v) ((_v)->bdev->bd_part ? \
34 (_v)->bdev->bd_part->nr_sects : \
35 get_capacity((_v)->bdev->bd_disk))
36
37unsigned long long vbd_size(struct vbd *vbd)
38{
39 return vbd_sz(vbd);
40}
41
42unsigned int vbd_info(struct vbd *vbd)
43{
44 return vbd->type | (vbd->readonly ? VDISK_READONLY : 0);
45}
46
47unsigned long vbd_secsize(struct vbd *vbd)
48{
49 return bdev_logical_block_size(vbd->bdev);
50}
51
52int vbd_create(struct blkif_st *blkif, blkif_vdev_t handle, unsigned major,
53 unsigned minor, int readonly, int cdrom)
54{
55 struct vbd *vbd;
56 struct block_device *bdev;
57
58 vbd = &blkif->vbd;
59 vbd->handle = handle;
60 vbd->readonly = readonly;
61 vbd->type = 0;
62
63 vbd->pdevice = MKDEV(major, minor);
64
65 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
66 FMODE_READ : FMODE_WRITE, NULL);
67
68 if (IS_ERR(bdev)) {
69 DPRINTK("vbd_creat: device %08x could not be opened.\n",
70 vbd->pdevice);
71 return -ENOENT;
72 }
73
74 vbd->bdev = bdev;
75 vbd->size = vbd_size(vbd);
76
77 if (vbd->bdev->bd_disk == NULL) {
78 DPRINTK("vbd_creat: device %08x doesn't exist.\n",
79 vbd->pdevice);
80 vbd_free(vbd);
81 return -ENOENT;
82 }
83
84 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
85 vbd->type |= VDISK_CDROM;
86 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
87 vbd->type |= VDISK_REMOVABLE;
88
89 DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
90 handle, blkif->domid);
91 return 0;
92}
93
94void vbd_free(struct vbd *vbd)
95{
96 if (vbd->bdev)
97 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
98 vbd->bdev = NULL;
99}
100
101int vbd_translate(struct phys_req *req, struct blkif_st *blkif, int operation)
102{
103 struct vbd *vbd = &blkif->vbd;
104 int rc = -EACCES;
105
106 if ((operation != READ) && vbd->readonly)
107 goto out;
108
109 if (unlikely((req->sector_number + req->nr_sects) > vbd_sz(vbd)))
110 goto out;
111
112 req->dev = vbd->pdevice;
113 req->bdev = vbd->bdev;
114 rc = 0;
115
116 out:
117 return rc;
118}
119
120void vbd_resize(struct blkif_st *blkif)
121{
122 struct vbd *vbd = &blkif->vbd;
123 struct xenbus_transaction xbt;
124 int err;
125 struct xenbus_device *dev = blkback_xenbus(blkif->be);
126 unsigned long long new_size = vbd_size(vbd);
127
128 printk(KERN_INFO "VBD Resize: Domid: %d, Device: (%d, %d)\n",
129 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
130 printk(KERN_INFO "VBD Resize: new size %llu\n", new_size);
131 vbd->size = new_size;
132again:
133 err = xenbus_transaction_start(&xbt);
134 if (err) {
135 printk(KERN_WARNING "Error starting transaction");
136 return;
137 }
138 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
139 vbd_size(vbd));
140 if (err) {
141 printk(KERN_WARNING "Error writing new size");
142 goto abort;
143 }
144 /*
145 * Write the current state; we will use this to synchronize
146 * the front-end. If the current state is "connected" the
147 * front-end will get the new size information online.
148 */
149 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
150 if (err) {
151 printk(KERN_WARNING "Error writing the state");
152 goto abort;
153 }
154
155 err = xenbus_transaction_end(xbt, 0);
156 if (err == -EAGAIN)
157 goto again;
158 if (err)
159 printk(KERN_WARNING "Error ending transaction");
160abort:
161 xenbus_transaction_end(xbt, 1);
162}
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
new file mode 100644
index 000000000000..b41ed65db2d3
--- /dev/null
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -0,0 +1,562 @@
1/* Xenbus code for blkif backend
2 Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
3 Copyright (C) 2005 XenSource Ltd
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18*/
19
20#include <stdarg.h>
21#include <linux/module.h>
22#include <linux/kthread.h>
23#include "common.h"
24
25#undef DPRINTK
26#define DPRINTK(fmt, args...) \
27 pr_debug("blkback/xenbus (%s:%d) " fmt ".\n", \
28 __func__, __LINE__, ##args)
29
30struct backend_info {
31 struct xenbus_device *dev;
32 struct blkif_st *blkif;
33 struct xenbus_watch backend_watch;
34 unsigned major;
35 unsigned minor;
36 char *mode;
37};
38
39static void connect(struct backend_info *);
40static int connect_ring(struct backend_info *);
41static void backend_changed(struct xenbus_watch *, const char **,
42 unsigned int);
43
44struct xenbus_device *blkback_xenbus(struct backend_info *be)
45{
46 return be->dev;
47}
48
49static int blkback_name(struct blkif_st *blkif, char *buf)
50{
51 char *devpath, *devname;
52 struct xenbus_device *dev = blkif->be->dev;
53
54 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
55 if (IS_ERR(devpath))
56 return PTR_ERR(devpath);
57
58 devname = strstr(devpath, "/dev/");
59 if (devname != NULL)
60 devname += strlen("/dev/");
61 else
62 devname = devpath;
63
64 snprintf(buf, TASK_COMM_LEN, "blkback.%d.%s", blkif->domid, devname);
65 kfree(devpath);
66
67 return 0;
68}
69
70static void update_blkif_status(struct blkif_st *blkif)
71{
72 int err;
73 char name[TASK_COMM_LEN];
74
75 /* Not ready to connect? */
76 if (!blkif->irq || !blkif->vbd.bdev)
77 return;
78
79 /* Already connected? */
80 if (blkif->be->dev->state == XenbusStateConnected)
81 return;
82
83 /* Attempt to connect: exit if we fail to. */
84 connect(blkif->be);
85 if (blkif->be->dev->state != XenbusStateConnected)
86 return;
87
88 err = blkback_name(blkif, name);
89 if (err) {
90 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
91 return;
92 }
93
94 err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
95 if (err) {
96 xenbus_dev_error(blkif->be->dev, err, "block flush");
97 return;
98 }
99 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
100
101 blkif->xenblkd = kthread_run(blkif_schedule, blkif, name);
102 if (IS_ERR(blkif->xenblkd)) {
103 err = PTR_ERR(blkif->xenblkd);
104 blkif->xenblkd = NULL;
105 xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
106 }
107}
108
109
110/*
111 * sysfs interface for VBD I/O requests
112 */
113
114#define VBD_SHOW(name, format, args...) \
115 static ssize_t show_##name(struct device *_dev, \
116 struct device_attribute *attr, \
117 char *buf) \
118 { \
119 struct xenbus_device *dev = to_xenbus_device(_dev); \
120 struct backend_info *be = dev_get_drvdata(&dev->dev); \
121 \
122 return sprintf(buf, format, ##args); \
123 } \
124 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
125
126VBD_SHOW(oo_req, "%d\n", be->blkif->st_oo_req);
127VBD_SHOW(rd_req, "%d\n", be->blkif->st_rd_req);
128VBD_SHOW(wr_req, "%d\n", be->blkif->st_wr_req);
129VBD_SHOW(br_req, "%d\n", be->blkif->st_br_req);
130VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect);
131VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect);
132
133static struct attribute *vbdstat_attrs[] = {
134 &dev_attr_oo_req.attr,
135 &dev_attr_rd_req.attr,
136 &dev_attr_wr_req.attr,
137 &dev_attr_br_req.attr,
138 &dev_attr_rd_sect.attr,
139 &dev_attr_wr_sect.attr,
140 NULL
141};
142
143static struct attribute_group vbdstat_group = {
144 .name = "statistics",
145 .attrs = vbdstat_attrs,
146};
147
148VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
149VBD_SHOW(mode, "%s\n", be->mode);
150
151int xenvbd_sysfs_addif(struct xenbus_device *dev)
152{
153 int error;
154
155 error = device_create_file(&dev->dev, &dev_attr_physical_device);
156 if (error)
157 goto fail1;
158
159 error = device_create_file(&dev->dev, &dev_attr_mode);
160 if (error)
161 goto fail2;
162
163 error = sysfs_create_group(&dev->dev.kobj, &vbdstat_group);
164 if (error)
165 goto fail3;
166
167 return 0;
168
169fail3: sysfs_remove_group(&dev->dev.kobj, &vbdstat_group);
170fail2: device_remove_file(&dev->dev, &dev_attr_mode);
171fail1: device_remove_file(&dev->dev, &dev_attr_physical_device);
172 return error;
173}
174
175void xenvbd_sysfs_delif(struct xenbus_device *dev)
176{
177 sysfs_remove_group(&dev->dev.kobj, &vbdstat_group);
178 device_remove_file(&dev->dev, &dev_attr_mode);
179 device_remove_file(&dev->dev, &dev_attr_physical_device);
180}
181
182static int blkback_remove(struct xenbus_device *dev)
183{
184 struct backend_info *be = dev_get_drvdata(&dev->dev);
185
186 DPRINTK("");
187
188 if (be->major || be->minor)
189 xenvbd_sysfs_delif(dev);
190
191 if (be->backend_watch.node) {
192 unregister_xenbus_watch(&be->backend_watch);
193 kfree(be->backend_watch.node);
194 be->backend_watch.node = NULL;
195 }
196
197 if (be->blkif) {
198 blkif_disconnect(be->blkif);
199 vbd_free(&be->blkif->vbd);
200 blkif_free(be->blkif);
201 be->blkif = NULL;
202 }
203
204 kfree(be);
205 dev_set_drvdata(&dev->dev, NULL);
206 return 0;
207}
208
209int blkback_barrier(struct xenbus_transaction xbt,
210 struct backend_info *be, int state)
211{
212 struct xenbus_device *dev = be->dev;
213 int err;
214
215 err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
216 "%d", state);
217 if (err)
218 xenbus_dev_fatal(dev, err, "writing feature-barrier");
219
220 return err;
221}
222
223/**
224 * Entry point to this code when a new device is created. Allocate the basic
225 * structures, and watch the store waiting for the hotplug scripts to tell us
226 * the device's physical major and minor numbers. Switch to InitWait.
227 */
228static int blkback_probe(struct xenbus_device *dev,
229 const struct xenbus_device_id *id)
230{
231 int err;
232 struct backend_info *be = kzalloc(sizeof(struct backend_info),
233 GFP_KERNEL);
234 if (!be) {
235 xenbus_dev_fatal(dev, -ENOMEM,
236 "allocating backend structure");
237 return -ENOMEM;
238 }
239 be->dev = dev;
240 dev_set_drvdata(&dev->dev, be);
241
242 be->blkif = blkif_alloc(dev->otherend_id);
243 if (IS_ERR(be->blkif)) {
244 err = PTR_ERR(be->blkif);
245 be->blkif = NULL;
246 xenbus_dev_fatal(dev, err, "creating block interface");
247 goto fail;
248 }
249
250 /* setup back pointer */
251 be->blkif->be = be;
252
253 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
254 "%s/%s", dev->nodename, "physical-device");
255 if (err)
256 goto fail;
257
258 err = xenbus_switch_state(dev, XenbusStateInitWait);
259 if (err)
260 goto fail;
261
262 return 0;
263
264fail:
265 DPRINTK("failed");
266 blkback_remove(dev);
267 return err;
268}
269
270
271/**
272 * Callback received when the hotplug scripts have placed the physical-device
273 * node. Read it and the mode node, and create a vbd. If the frontend is
274 * ready, connect.
275 */
276static void backend_changed(struct xenbus_watch *watch,
277 const char **vec, unsigned int len)
278{
279 int err;
280 unsigned major;
281 unsigned minor;
282 struct backend_info *be
283 = container_of(watch, struct backend_info, backend_watch);
284 struct xenbus_device *dev = be->dev;
285 int cdrom = 0;
286 char *device_type;
287
288 DPRINTK("");
289
290 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
291 &major, &minor);
292 if (XENBUS_EXIST_ERR(err)) {
293 /* Since this watch will fire once immediately after it is
294 registered, we expect this. Ignore it, and wait for the
295 hotplug scripts. */
296 return;
297 }
298 if (err != 2) {
299 xenbus_dev_fatal(dev, err, "reading physical-device");
300 return;
301 }
302
303 if ((be->major || be->minor) &&
304 ((be->major != major) || (be->minor != minor))) {
305 printk(KERN_WARNING
306 "blkback: changing physical device (from %x:%x to "
307 "%x:%x) not supported.\n", be->major, be->minor,
308 major, minor);
309 return;
310 }
311
312 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
313 if (IS_ERR(be->mode)) {
314 err = PTR_ERR(be->mode);
315 be->mode = NULL;
316 xenbus_dev_fatal(dev, err, "reading mode");
317 return;
318 }
319
320 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
321 if (!IS_ERR(device_type)) {
322 cdrom = strcmp(device_type, "cdrom") == 0;
323 kfree(device_type);
324 }
325
326 if (be->major == 0 && be->minor == 0) {
327 /* Front end dir is a number, which is used as the handle. */
328
329 char *p = strrchr(dev->otherend, '/') + 1;
330 long handle;
331 err = strict_strtoul(p, 0, &handle);
332 if (err)
333 return;
334
335 be->major = major;
336 be->minor = minor;
337
338 err = vbd_create(be->blkif, handle, major, minor,
339 (NULL == strchr(be->mode, 'w')), cdrom);
340 if (err) {
341 be->major = be->minor = 0;
342 xenbus_dev_fatal(dev, err, "creating vbd structure");
343 return;
344 }
345
346 err = xenvbd_sysfs_addif(dev);
347 if (err) {
348 vbd_free(&be->blkif->vbd);
349 be->major = be->minor = 0;
350 xenbus_dev_fatal(dev, err, "creating sysfs entries");
351 return;
352 }
353
354 /* We're potentially connected now */
355 update_blkif_status(be->blkif);
356 }
357}
358
359
360/**
361 * Callback received when the frontend's state changes.
362 */
363static void frontend_changed(struct xenbus_device *dev,
364 enum xenbus_state frontend_state)
365{
366 struct backend_info *be = dev_get_drvdata(&dev->dev);
367 int err;
368
369 DPRINTK("%s", xenbus_strstate(frontend_state));
370
371 switch (frontend_state) {
372 case XenbusStateInitialising:
373 if (dev->state == XenbusStateClosed) {
374 printk(KERN_INFO "%s: %s: prepare for reconnect\n",
375 __func__, dev->nodename);
376 xenbus_switch_state(dev, XenbusStateInitWait);
377 }
378 break;
379
380 case XenbusStateInitialised:
381 case XenbusStateConnected:
382 /* Ensure we connect even when two watches fire in
383 close successsion and we miss the intermediate value
384 of frontend_state. */
385 if (dev->state == XenbusStateConnected)
386 break;
387
388 /* Enforce precondition before potential leak point.
389 * blkif_disconnect() is idempotent.
390 */
391 blkif_disconnect(be->blkif);
392
393 err = connect_ring(be);
394 if (err)
395 break;
396 update_blkif_status(be->blkif);
397 break;
398
399 case XenbusStateClosing:
400 blkif_disconnect(be->blkif);
401 xenbus_switch_state(dev, XenbusStateClosing);
402 break;
403
404 case XenbusStateClosed:
405 xenbus_switch_state(dev, XenbusStateClosed);
406 if (xenbus_dev_is_online(dev))
407 break;
408 /* fall through if not online */
409 case XenbusStateUnknown:
410 /* implies blkif_disconnect() via blkback_remove() */
411 device_unregister(&dev->dev);
412 break;
413
414 default:
415 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
416 frontend_state);
417 break;
418 }
419}
420
421
422/* ** Connection ** */
423
424
425/**
426 * Write the physical details regarding the block device to the store, and
427 * switch to Connected state.
428 */
429static void connect(struct backend_info *be)
430{
431 struct xenbus_transaction xbt;
432 int err;
433 struct xenbus_device *dev = be->dev;
434
435 DPRINTK("%s", dev->otherend);
436
437 /* Supply the information about the device the frontend needs */
438again:
439 err = xenbus_transaction_start(&xbt);
440 if (err) {
441 xenbus_dev_fatal(dev, err, "starting transaction");
442 return;
443 }
444
445 err = blkback_barrier(xbt, be, 1);
446 if (err)
447 goto abort;
448
449 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
450 vbd_size(&be->blkif->vbd));
451 if (err) {
452 xenbus_dev_fatal(dev, err, "writing %s/sectors",
453 dev->nodename);
454 goto abort;
455 }
456
457 /* FIXME: use a typename instead */
458 err = xenbus_printf(xbt, dev->nodename, "info", "%u",
459 vbd_info(&be->blkif->vbd));
460 if (err) {
461 xenbus_dev_fatal(dev, err, "writing %s/info",
462 dev->nodename);
463 goto abort;
464 }
465 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
466 vbd_secsize(&be->blkif->vbd));
467 if (err) {
468 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
469 dev->nodename);
470 goto abort;
471 }
472
473 err = xenbus_transaction_end(xbt, 0);
474 if (err == -EAGAIN)
475 goto again;
476 if (err)
477 xenbus_dev_fatal(dev, err, "ending transaction");
478
479 err = xenbus_switch_state(dev, XenbusStateConnected);
480 if (err)
481 xenbus_dev_fatal(dev, err, "switching to Connected state",
482 dev->nodename);
483
484 return;
485 abort:
486 xenbus_transaction_end(xbt, 1);
487}
488
489
490static int connect_ring(struct backend_info *be)
491{
492 struct xenbus_device *dev = be->dev;
493 unsigned long ring_ref;
494 unsigned int evtchn;
495 char protocol[64] = "";
496 int err;
497
498 DPRINTK("%s", dev->otherend);
499
500 err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu",
501 &ring_ref, "event-channel", "%u", &evtchn, NULL);
502 if (err) {
503 xenbus_dev_fatal(dev, err,
504 "reading %s/ring-ref and event-channel",
505 dev->otherend);
506 return err;
507 }
508
509 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
510 err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
511 "%63s", protocol, NULL);
512 if (err)
513 strcpy(protocol, "unspecified, assuming native");
514 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
515 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
516 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
517 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
518 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
519 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
520 else {
521 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
522 return -1;
523 }
524 printk(KERN_INFO
525 "blkback: ring-ref %ld, event-channel %d, protocol %d (%s)\n",
526 ring_ref, evtchn, be->blkif->blk_protocol, protocol);
527
528 /* Map the shared frame, irq etc. */
529 err = blkif_map(be->blkif, ring_ref, evtchn);
530 if (err) {
531 xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u",
532 ring_ref, evtchn);
533 return err;
534 }
535
536 return 0;
537}
538
539
540/* ** Driver Registration ** */
541
542
543static const struct xenbus_device_id blkback_ids[] = {
544 { "vbd" },
545 { "" }
546};
547
548
549static struct xenbus_driver blkback = {
550 .name = "vbd",
551 .owner = THIS_MODULE,
552 .ids = blkback_ids,
553 .probe = blkback_probe,
554 .remove = blkback_remove,
555 .otherend_changed = frontend_changed
556};
557
558
559int blkif_xenbus_init(void)
560{
561 return xenbus_register_backend(&blkback);
562}
generated by cgit v1.2.2 (git 2.25.0) at 2025-01-09 03:00:59 -0500