?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
f2fs: do more integrity verification for superblock
[linux-2.6/btrfs-unstable.git] / drivers / scsi / xen-scsifront.c
blob9dc8687bf0480e53b2d89431ece47f8504fd5779
1 /*
2 * Xen SCSI frontend driver
3 *
4 * Copyright (c) 2008, FUJITSU Limited
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 <linux/module.h>
32 #include <linux/kernel.h>
33 #include <linux/device.h>
34 #include <linux/wait.h>
35 #include <linux/interrupt.h>
36 #include <linux/mutex.h>
37 #include <linux/spinlock.h>
38 #include <linux/sched.h>
39 #include <linux/blkdev.h>
40 #include <linux/pfn.h>
41 #include <linux/slab.h>
42 #include <linux/bitops.h>
43
44 #include <scsi/scsi_cmnd.h>
45 #include <scsi/scsi_device.h>
46 #include <scsi/scsi.h>
47 #include <scsi/scsi_host.h>
48
49 #include <xen/xen.h>
50 #include <xen/xenbus.h>
51 #include <xen/grant_table.h>
52 #include <xen/events.h>
53 #include <xen/page.h>
54
55 #include <xen/interface/grant_table.h>
56 #include <xen/interface/io/vscsiif.h>
57 #include <xen/interface/io/protocols.h>
58
59 #include <asm/xen/hypervisor.h>
60
61
62 #define GRANT_INVALID_REF 0
63
64 #define VSCSIFRONT_OP_ADD_LUN 1
65 #define VSCSIFRONT_OP_DEL_LUN 2
66 #define VSCSIFRONT_OP_READD_LUN 3
67
68 /* Tuning point. */
69 #define VSCSIIF_DEFAULT_CMD_PER_LUN 10
70 #define VSCSIIF_MAX_TARGET 64
71 #define VSCSIIF_MAX_LUN 255
72
73 #define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE)
74 #define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE
75
76 #define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \
77 sizeof(struct scsiif_request_segment)))
78
79 struct vscsifrnt_shadow {
80 /* command between backend and frontend */
81 unsigned char act;
82 uint16_t rqid;
83
84 unsigned int nr_grants; /* number of grants in gref[] */
85 struct scsiif_request_segment *sg; /* scatter/gather elements */
86
87 /* Do reset or abort function. */
88 wait_queue_head_t wq_reset; /* reset work queue */
89 int wait_reset; /* reset work queue condition */
90 int32_t rslt_reset; /* reset response status: */
91 /* SUCCESS or FAILED or: */
92 #define RSLT_RESET_WAITING 0
93 #define RSLT_RESET_ERR -1
94
95 /* Requested struct scsi_cmnd is stored from kernel. */
96 struct scsi_cmnd *sc;
97 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];
98 };
99
100 struct vscsifrnt_info {
101 struct xenbus_device *dev;
102
103 struct Scsi_Host *host;
104 int host_active;
105
106 unsigned int evtchn;
107 unsigned int irq;
108
109 grant_ref_t ring_ref;
110 struct vscsiif_front_ring ring;
111 struct vscsiif_response ring_rsp;
112
113 spinlock_t shadow_lock;
114 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);
115 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];
116
117 /* Following items are protected by the host lock. */
118 wait_queue_head_t wq_sync;
119 wait_queue_head_t wq_pause;
120 unsigned int wait_ring_available:1;
121 unsigned int waiting_pause:1;
122 unsigned int pause:1;
123 unsigned callers;
124
125 char dev_state_path[64];
126 struct task_struct *curr;
127 };
128
129 static DEFINE_MUTEX(scsifront_mutex);
130
131 static void scsifront_wake_up(struct vscsifrnt_info *info)
132 {
133 info->wait_ring_available = 0;
134 wake_up(&info->wq_sync);
135 }
136
137 static int scsifront_get_rqid(struct vscsifrnt_info *info)
138 {
139 unsigned long flags;
140 int free;
141
142 spin_lock_irqsave(&info->shadow_lock, flags);
143
144 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
145 __clear_bit(free, info->shadow_free_bitmap);
146
147 spin_unlock_irqrestore(&info->shadow_lock, flags);
148
149 return free;
150 }
151
152 static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
153 {
154 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
155
156 __set_bit(id, info->shadow_free_bitmap);
157 info->shadow[id] = NULL;
158
159 return empty || info->wait_ring_available;
160 }
161
162 static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
163 {
164 unsigned long flags;
165 int kick;
166
167 spin_lock_irqsave(&info->shadow_lock, flags);
168 kick = _scsifront_put_rqid(info, id);
169 spin_unlock_irqrestore(&info->shadow_lock, flags);
170
171 if (kick)
172 scsifront_wake_up(info);
173 }
174
175 static struct vscsiif_request *scsifront_pre_req(struct vscsifrnt_info *info)
176 {
177 struct vscsiif_front_ring *ring = &(info->ring);
178 struct vscsiif_request *ring_req;
179 uint32_t id;
180
181 id = scsifront_get_rqid(info); /* use id in response */
182 if (id >= VSCSIIF_MAX_REQS)
183 return NULL;
184
185 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);
186
187 ring->req_prod_pvt++;
188
189 ring_req->rqid = (uint16_t)id;
190
191 return ring_req;
192 }
193
194 static void scsifront_do_request(struct vscsifrnt_info *info)
195 {
196 struct vscsiif_front_ring *ring = &(info->ring);
197 int notify;
198
199 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);
200 if (notify)
201 notify_remote_via_irq(info->irq);
202 }
203
204 static void scsifront_gnttab_done(struct vscsifrnt_info *info, uint32_t id)
205 {
206 struct vscsifrnt_shadow *s = info->shadow[id];
207 int i;
208
209 if (s->sc->sc_data_direction == DMA_NONE)
210 return;
211
212 for (i = 0; i < s->nr_grants; i++) {
213 if (unlikely(gnttab_query_foreign_access(s->gref[i]) != 0)) {
214 shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME
215 "grant still in use by backend\n");
216 BUG();
217 }
218 gnttab_end_foreign_access(s->gref[i], 0, 0UL);
219 }
220
221 kfree(s->sg);
222 }
223
224 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
225 struct vscsiif_response *ring_rsp)
226 {
227 struct scsi_cmnd *sc;
228 uint32_t id;
229 uint8_t sense_len;
230
231 id = ring_rsp->rqid;
232 sc = info->shadow[id]->sc;
233
234 BUG_ON(sc == NULL);
235
236 scsifront_gnttab_done(info, id);
237 scsifront_put_rqid(info, id);
238
239 sc->result = ring_rsp->rslt;
240 scsi_set_resid(sc, ring_rsp->residual_len);
241
242 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
243 ring_rsp->sense_len);
244
245 if (sense_len)
246 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
247
248 sc->scsi_done(sc);
249 }
250
251 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
252 struct vscsiif_response *ring_rsp)
253 {
254 uint16_t id = ring_rsp->rqid;
255 unsigned long flags;
256 struct vscsifrnt_shadow *shadow = info->shadow[id];
257 int kick;
258
259 spin_lock_irqsave(&info->shadow_lock, flags);
260 shadow->wait_reset = 1;
261 switch (shadow->rslt_reset) {
262 case RSLT_RESET_WAITING:
263 shadow->rslt_reset = ring_rsp->rslt;
264 break;
265 case RSLT_RESET_ERR:
266 kick = _scsifront_put_rqid(info, id);
267 spin_unlock_irqrestore(&info->shadow_lock, flags);
268 kfree(shadow);
269 if (kick)
270 scsifront_wake_up(info);
271 return;
272 default:
273 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
274 "bad reset state %d, possibly leaking %u\n",
275 shadow->rslt_reset, id);
276 break;
277 }
278 spin_unlock_irqrestore(&info->shadow_lock, flags);
279
280 wake_up(&shadow->wq_reset);
281 }
282
283 static void scsifront_do_response(struct vscsifrnt_info *info,
284 struct vscsiif_response *ring_rsp)
285 {
286 if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
287 test_bit(ring_rsp->rqid, info->shadow_free_bitmap),
288 "illegal rqid %u returned by backend!\n", ring_rsp->rqid))
289 return;
290
291 if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB)
292 scsifront_cdb_cmd_done(info, ring_rsp);
293 else
294 scsifront_sync_cmd_done(info, ring_rsp);
295 }
296
297 static int scsifront_ring_drain(struct vscsifrnt_info *info)
298 {
299 struct vscsiif_response *ring_rsp;
300 RING_IDX i, rp;
301 int more_to_do = 0;
302
303 rp = info->ring.sring->rsp_prod;
304 rmb(); /* ordering required respective to dom0 */
305 for (i = info->ring.rsp_cons; i != rp; i++) {
306 ring_rsp = RING_GET_RESPONSE(&info->ring, i);
307 scsifront_do_response(info, ring_rsp);
308 }
309
310 info->ring.rsp_cons = i;
311
312 if (i != info->ring.req_prod_pvt)
313 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
314 else
315 info->ring.sring->rsp_event = i + 1;
316
317 return more_to_do;
318 }
319
320 static int scsifront_cmd_done(struct vscsifrnt_info *info)
321 {
322 int more_to_do;
323 unsigned long flags;
324
325 spin_lock_irqsave(info->host->host_lock, flags);
326
327 more_to_do = scsifront_ring_drain(info);
328
329 info->wait_ring_available = 0;
330
331 spin_unlock_irqrestore(info->host->host_lock, flags);
332
333 wake_up(&info->wq_sync);
334
335 return more_to_do;
336 }
337
338 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
339 {
340 struct vscsifrnt_info *info = dev_id;
341
342 while (scsifront_cmd_done(info))
343 /* Yield point for this unbounded loop. */
344 cond_resched();
345
346 return IRQ_HANDLED;
347 }
348
349 static void scsifront_finish_all(struct vscsifrnt_info *info)
350 {
351 unsigned i;
352 struct vscsiif_response resp;
353
354 scsifront_ring_drain(info);
355
356 for (i = 0; i < VSCSIIF_MAX_REQS; i++) {
357 if (test_bit(i, info->shadow_free_bitmap))
358 continue;
359 resp.rqid = i;
360 resp.sense_len = 0;
361 resp.rslt = DID_RESET << 16;
362 resp.residual_len = 0;
363 scsifront_do_response(info, &resp);
364 }
365 }
366
367 static int map_data_for_request(struct vscsifrnt_info *info,
368 struct scsi_cmnd *sc,
369 struct vscsiif_request *ring_req,
370 struct vscsifrnt_shadow *shadow)
371 {
372 grant_ref_t gref_head;
373 struct page *page;
374 int err, ref, ref_cnt = 0;
375 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
376 unsigned int i, off, len, bytes;
377 unsigned int data_len = scsi_bufflen(sc);
378 unsigned int data_grants = 0, seg_grants = 0;
379 struct scatterlist *sg;
380 struct scsiif_request_segment *seg;
381
382 ring_req->nr_segments = 0;
383 if (sc->sc_data_direction == DMA_NONE || !data_len)
384 return 0;
385
386 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
387 data_grants += PFN_UP(sg->offset + sg->length);
388
389 if (data_grants > VSCSIIF_SG_TABLESIZE) {
390 if (data_grants > info->host->sg_tablesize) {
391 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
392 "Unable to map request_buffer for command!\n");
393 return -E2BIG;
394 }
395 seg_grants = vscsiif_grants_sg(data_grants);
396 shadow->sg = kcalloc(data_grants,
397 sizeof(struct scsiif_request_segment), GFP_ATOMIC);
398 if (!shadow->sg)
399 return -ENOMEM;
400 }
401 seg = shadow->sg ? : ring_req->seg;
402
403 err = gnttab_alloc_grant_references(seg_grants + data_grants,
404 &gref_head);
405 if (err) {
406 kfree(shadow->sg);
407 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
408 "gnttab_alloc_grant_references() error\n");
409 return -ENOMEM;
410 }
411
412 if (seg_grants) {
413 page = virt_to_page(seg);
414 off = (unsigned long)seg & ~PAGE_MASK;
415 len = sizeof(struct scsiif_request_segment) * data_grants;
416 while (len > 0) {
417 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
418
419 ref = gnttab_claim_grant_reference(&gref_head);
420 BUG_ON(ref == -ENOSPC);
421
422 gnttab_grant_foreign_access_ref(ref,
423 info->dev->otherend_id,
424 xen_page_to_gfn(page), 1);
425 shadow->gref[ref_cnt] = ref;
426 ring_req->seg[ref_cnt].gref = ref;
427 ring_req->seg[ref_cnt].offset = (uint16_t)off;
428 ring_req->seg[ref_cnt].length = (uint16_t)bytes;
429
430 page++;
431 len -= bytes;
432 off = 0;
433 ref_cnt++;
434 }
435 BUG_ON(seg_grants < ref_cnt);
436 seg_grants = ref_cnt;
437 }
438
439 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
440 page = sg_page(sg);
441 off = sg->offset;
442 len = sg->length;
443
444 while (len > 0 && data_len > 0) {
445 /*
446 * sg sends a scatterlist that is larger than
447 * the data_len it wants transferred for certain
448 * IO sizes.
449 */
450 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
451 bytes = min(bytes, data_len);
452
453 ref = gnttab_claim_grant_reference(&gref_head);
454 BUG_ON(ref == -ENOSPC);
455
456 gnttab_grant_foreign_access_ref(ref,
457 info->dev->otherend_id,
458 xen_page_to_gfn(page),
459 grant_ro);
460
461 shadow->gref[ref_cnt] = ref;
462 seg->gref = ref;
463 seg->offset = (uint16_t)off;
464 seg->length = (uint16_t)bytes;
465
466 page++;
467 seg++;
468 len -= bytes;
469 data_len -= bytes;
470 off = 0;
471 ref_cnt++;
472 }
473 }
474
475 if (seg_grants)
476 ring_req->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
477 else
478 ring_req->nr_segments = (uint8_t)ref_cnt;
479 shadow->nr_grants = ref_cnt;
480
481 return 0;
482 }
483
484 static struct vscsiif_request *scsifront_command2ring(
485 struct vscsifrnt_info *info, struct scsi_cmnd *sc,
486 struct vscsifrnt_shadow *shadow)
487 {
488 struct vscsiif_request *ring_req;
489
490 memset(shadow, 0, sizeof(*shadow));
491
492 ring_req = scsifront_pre_req(info);
493 if (!ring_req)
494 return NULL;
495
496 info->shadow[ring_req->rqid] = shadow;
497 shadow->rqid = ring_req->rqid;
498
499 ring_req->id = sc->device->id;
500 ring_req->lun = sc->device->lun;
501 ring_req->channel = sc->device->channel;
502 ring_req->cmd_len = sc->cmd_len;
503
504 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
505
506 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
507
508 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction;
509 ring_req->timeout_per_command = sc->request->timeout / HZ;
510
511 return ring_req;
512 }
513
514 static int scsifront_enter(struct vscsifrnt_info *info)
515 {
516 if (info->pause)
517 return 1;
518 info->callers++;
519 return 0;
520 }
521
522 static void scsifront_return(struct vscsifrnt_info *info)
523 {
524 info->callers--;
525 if (info->callers)
526 return;
527
528 if (!info->waiting_pause)
529 return;
530
531 info->waiting_pause = 0;
532 wake_up(&info->wq_pause);
533 }
534
535 static int scsifront_queuecommand(struct Scsi_Host *shost,
536 struct scsi_cmnd *sc)
537 {
538 struct vscsifrnt_info *info = shost_priv(shost);
539 struct vscsiif_request *ring_req;
540 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
541 unsigned long flags;
542 int err;
543 uint16_t rqid;
544
545 spin_lock_irqsave(shost->host_lock, flags);
546 if (scsifront_enter(info)) {
547 spin_unlock_irqrestore(shost->host_lock, flags);
548 return SCSI_MLQUEUE_HOST_BUSY;
549 }
550 if (RING_FULL(&info->ring))
551 goto busy;
552
553 ring_req = scsifront_command2ring(info, sc, shadow);
554 if (!ring_req)
555 goto busy;
556
557 sc->result = 0;
558
559 rqid = ring_req->rqid;
560 ring_req->act = VSCSIIF_ACT_SCSI_CDB;
561
562 shadow->sc = sc;
563 shadow->act = VSCSIIF_ACT_SCSI_CDB;
564
565 err = map_data_for_request(info, sc, ring_req, shadow);
566 if (err < 0) {
567 pr_debug("%s: err %d\n", __func__, err);
568 scsifront_put_rqid(info, rqid);
569 scsifront_return(info);
570 spin_unlock_irqrestore(shost->host_lock, flags);
571 if (err == -ENOMEM)
572 return SCSI_MLQUEUE_HOST_BUSY;
573 sc->result = DID_ERROR << 16;
574 sc->scsi_done(sc);
575 return 0;
576 }
577
578 scsifront_do_request(info);
579 scsifront_return(info);
580 spin_unlock_irqrestore(shost->host_lock, flags);
581
582 return 0;
583
584 busy:
585 scsifront_return(info);
586 spin_unlock_irqrestore(shost->host_lock, flags);
587 pr_debug("%s: busy\n", __func__);
588 return SCSI_MLQUEUE_HOST_BUSY;
589 }
590
591 /*
592 * Any exception handling (reset or abort) must be forwarded to the backend.
593 * We have to wait until an answer is returned. This answer contains the
594 * result to be returned to the requestor.
595 */
596 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
597 {
598 struct Scsi_Host *host = sc->device->host;
599 struct vscsifrnt_info *info = shost_priv(host);
600 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
601 struct vscsiif_request *ring_req;
602 int err = 0;
603
604 shadow = kmalloc(sizeof(*shadow), GFP_NOIO);
605 if (!shadow)
606 return FAILED;
607
608 spin_lock_irq(host->host_lock);
609
610 for (;;) {
611 if (!RING_FULL(&info->ring)) {
612 ring_req = scsifront_command2ring(info, sc, shadow);
613 if (ring_req)
614 break;
615 }
616 if (err || info->pause) {
617 spin_unlock_irq(host->host_lock);
618 kfree(shadow);
619 return FAILED;
620 }
621 info->wait_ring_available = 1;
622 spin_unlock_irq(host->host_lock);
623 err = wait_event_interruptible(info->wq_sync,
624 !info->wait_ring_available);
625 spin_lock_irq(host->host_lock);
626 }
627
628 if (scsifront_enter(info)) {
629 spin_unlock_irq(host->host_lock);
630 return FAILED;
631 }
632
633 ring_req->act = act;
634 ring_req->ref_rqid = s->rqid;
635
636 shadow->act = act;
637 shadow->rslt_reset = RSLT_RESET_WAITING;
638 init_waitqueue_head(&shadow->wq_reset);
639
640 ring_req->nr_segments = 0;
641
642 scsifront_do_request(info);
643
644 spin_unlock_irq(host->host_lock);
645 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
646 spin_lock_irq(host->host_lock);
647
648 if (!err) {
649 err = shadow->rslt_reset;
650 scsifront_put_rqid(info, shadow->rqid);
651 kfree(shadow);
652 } else {
653 spin_lock(&info->shadow_lock);
654 shadow->rslt_reset = RSLT_RESET_ERR;
655 spin_unlock(&info->shadow_lock);
656 err = FAILED;
657 }
658
659 scsifront_return(info);
660 spin_unlock_irq(host->host_lock);
661 return err;
662 }
663
664 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
665 {
666 pr_debug("%s\n", __func__);
667 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
668 }
669
670 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
671 {
672 pr_debug("%s\n", __func__);
673 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
674 }
675
676 static int scsifront_sdev_configure(struct scsi_device *sdev)
677 {
678 struct vscsifrnt_info *info = shost_priv(sdev->host);
679
680 if (info && current == info->curr)
681 xenbus_printf(XBT_NIL, info->dev->nodename,
682 info->dev_state_path, "%d", XenbusStateConnected);
683
684 return 0;
685 }
686
687 static void scsifront_sdev_destroy(struct scsi_device *sdev)
688 {
689 struct vscsifrnt_info *info = shost_priv(sdev->host);
690
691 if (info && current == info->curr)
692 xenbus_printf(XBT_NIL, info->dev->nodename,
693 info->dev_state_path, "%d", XenbusStateClosed);
694 }
695
696 static struct scsi_host_template scsifront_sht = {
697 .module = THIS_MODULE,
698 .name = "Xen SCSI frontend driver",
699 .queuecommand = scsifront_queuecommand,
700 .eh_abort_handler = scsifront_eh_abort_handler,
701 .eh_device_reset_handler = scsifront_dev_reset_handler,
702 .slave_configure = scsifront_sdev_configure,
703 .slave_destroy = scsifront_sdev_destroy,
704 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN,
705 .can_queue = VSCSIIF_MAX_REQS,
706 .this_id = -1,
707 .cmd_size = sizeof(struct vscsifrnt_shadow),
708 .sg_tablesize = VSCSIIF_SG_TABLESIZE,
709 .use_clustering = DISABLE_CLUSTERING,
710 .proc_name = "scsifront",
711 };
712
713 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
714 {
715 struct xenbus_device *dev = info->dev;
716 struct vscsiif_sring *sring;
717 grant_ref_t gref;
718 int err = -ENOMEM;
719
720 /***** Frontend to Backend ring start *****/
721 sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
722 if (!sring) {
723 xenbus_dev_fatal(dev, err,
724 "fail to allocate shared ring (Front to Back)");
725 return err;
726 }
727 SHARED_RING_INIT(sring);
728 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
729
730 err = xenbus_grant_ring(dev, sring, 1, &gref);
731 if (err < 0) {
732 free_page((unsigned long)sring);
733 xenbus_dev_fatal(dev, err,
734 "fail to grant shared ring (Front to Back)");
735 return err;
736 }
737 info->ring_ref = gref;
738
739 err = xenbus_alloc_evtchn(dev, &info->evtchn);
740 if (err) {
741 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
742 goto free_gnttab;
743 }
744
745 err = bind_evtchn_to_irq(info->evtchn);
746 if (err <= 0) {
747 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
748 goto free_gnttab;
749 }
750
751 info->irq = err;
752
753 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
754 IRQF_ONESHOT, "scsifront", info);
755 if (err) {
756 xenbus_dev_fatal(dev, err, "request_threaded_irq");
757 goto free_irq;
758 }
759
760 return 0;
761
762 /* free resource */
763 free_irq:
764 unbind_from_irqhandler(info->irq, info);
765 free_gnttab:
766 gnttab_end_foreign_access(info->ring_ref, 0,
767 (unsigned long)info->ring.sring);
768
769 return err;
770 }
771
772 static void scsifront_free_ring(struct vscsifrnt_info *info)
773 {
774 unbind_from_irqhandler(info->irq, info);
775 gnttab_end_foreign_access(info->ring_ref, 0,
776 (unsigned long)info->ring.sring);
777 }
778
779 static int scsifront_init_ring(struct vscsifrnt_info *info)
780 {
781 struct xenbus_device *dev = info->dev;
782 struct xenbus_transaction xbt;
783 int err;
784
785 pr_debug("%s\n", __func__);
786
787 err = scsifront_alloc_ring(info);
788 if (err)
789 return err;
790 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
791
792 again:
793 err = xenbus_transaction_start(&xbt);
794 if (err)
795 xenbus_dev_fatal(dev, err, "starting transaction");
796
797 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
798 info->ring_ref);
799 if (err) {
800 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
801 goto fail;
802 }
803
804 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
805 info->evtchn);
806
807 if (err) {
808 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
809 goto fail;
810 }
811
812 err = xenbus_transaction_end(xbt, 0);
813 if (err) {
814 if (err == -EAGAIN)
815 goto again;
816 xenbus_dev_fatal(dev, err, "completing transaction");
817 goto free_sring;
818 }
819
820 return 0;
821
822 fail:
823 xenbus_transaction_end(xbt, 1);
824 free_sring:
825 scsifront_free_ring(info);
826
827 return err;
828 }
829
830
831 static int scsifront_probe(struct xenbus_device *dev,
832 const struct xenbus_device_id *id)
833 {
834 struct vscsifrnt_info *info;
835 struct Scsi_Host *host;
836 int err = -ENOMEM;
837 char name[TASK_COMM_LEN];
838
839 host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
840 if (!host) {
841 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
842 return err;
843 }
844 info = (struct vscsifrnt_info *)host->hostdata;
845
846 dev_set_drvdata(&dev->dev, info);
847 info->dev = dev;
848
849 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
850
851 err = scsifront_init_ring(info);
852 if (err) {
853 scsi_host_put(host);
854 return err;
855 }
856
857 init_waitqueue_head(&info->wq_sync);
858 init_waitqueue_head(&info->wq_pause);
859 spin_lock_init(&info->shadow_lock);
860
861 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
862
863 host->max_id = VSCSIIF_MAX_TARGET;
864 host->max_channel = 0;
865 host->max_lun = VSCSIIF_MAX_LUN;
866 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
867 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
868
869 err = scsi_add_host(host, &dev->dev);
870 if (err) {
871 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
872 goto free_sring;
873 }
874 info->host = host;
875 info->host_active = 1;
876
877 xenbus_switch_state(dev, XenbusStateInitialised);
878
879 return 0;
880
881 free_sring:
882 scsifront_free_ring(info);
883 scsi_host_put(host);
884 return err;
885 }
886
887 static int scsifront_resume(struct xenbus_device *dev)
888 {
889 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
890 struct Scsi_Host *host = info->host;
891 int err;
892
893 spin_lock_irq(host->host_lock);
894
895 /* Finish all still pending commands. */
896 scsifront_finish_all(info);
897
898 spin_unlock_irq(host->host_lock);
899
900 /* Reconnect to dom0. */
901 scsifront_free_ring(info);
902 err = scsifront_init_ring(info);
903 if (err) {
904 dev_err(&dev->dev, "fail to resume %d\n", err);
905 scsi_host_put(host);
906 return err;
907 }
908
909 xenbus_switch_state(dev, XenbusStateInitialised);
910
911 return 0;
912 }
913
914 static int scsifront_suspend(struct xenbus_device *dev)
915 {
916 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
917 struct Scsi_Host *host = info->host;
918 int err = 0;
919
920 /* No new commands for the backend. */
921 spin_lock_irq(host->host_lock);
922 info->pause = 1;
923 while (info->callers && !err) {
924 info->waiting_pause = 1;
925 info->wait_ring_available = 0;
926 spin_unlock_irq(host->host_lock);
927 wake_up(&info->wq_sync);
928 err = wait_event_interruptible(info->wq_pause,
929 !info->waiting_pause);
930 spin_lock_irq(host->host_lock);
931 }
932 spin_unlock_irq(host->host_lock);
933 return err;
934 }
935
936 static int scsifront_remove(struct xenbus_device *dev)
937 {
938 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
939
940 pr_debug("%s: %s removed\n", __func__, dev->nodename);
941
942 mutex_lock(&scsifront_mutex);
943 if (info->host_active) {
944 /* Scsi_host not yet removed */
945 scsi_remove_host(info->host);
946 info->host_active = 0;
947 }
948 mutex_unlock(&scsifront_mutex);
949
950 scsifront_free_ring(info);
951 scsi_host_put(info->host);
952
953 return 0;
954 }
955
956 static void scsifront_disconnect(struct vscsifrnt_info *info)
957 {
958 struct xenbus_device *dev = info->dev;
959 struct Scsi_Host *host = info->host;
960
961 pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
962
963 /*
964 * When this function is executed, all devices of
965 * Frontend have been deleted.
966 * Therefore, it need not block I/O before remove_host.
967 */
968
969 mutex_lock(&scsifront_mutex);
970 if (info->host_active) {
971 scsi_remove_host(host);
972 info->host_active = 0;
973 }
974 mutex_unlock(&scsifront_mutex);
975
976 xenbus_frontend_closed(dev);
977 }
978
979 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
980 {
981 struct xenbus_device *dev = info->dev;
982 int i, err = 0;
983 char str[64];
984 char **dir;
985 unsigned int dir_n = 0;
986 unsigned int device_state;
987 unsigned int hst, chn, tgt, lun;
988 struct scsi_device *sdev;
989
990 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
991 if (IS_ERR(dir))
992 return;
993
994 /* mark current task as the one allowed to modify device states */
995 BUG_ON(info->curr);
996 info->curr = current;
997
998 for (i = 0; i < dir_n; i++) {
999 /* read status */
1000 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
1001 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
1002 &device_state);
1003 if (XENBUS_EXIST_ERR(err))
1004 continue;
1005
1006 /* virtual SCSI device */
1007 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
1008 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
1009 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
1010 if (XENBUS_EXIST_ERR(err))
1011 continue;
1012
1013 /*
1014 * Front device state path, used in slave_configure called
1015 * on successfull scsi_add_device, and in slave_destroy called
1016 * on remove of a device.
1017 */
1018 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
1019 "vscsi-devs/%s/state", dir[i]);
1020
1021 switch (op) {
1022 case VSCSIFRONT_OP_ADD_LUN:
1023 if (device_state != XenbusStateInitialised)
1024 break;
1025
1026 if (scsi_add_device(info->host, chn, tgt, lun)) {
1027 dev_err(&dev->dev, "scsi_add_device\n");
1028 xenbus_printf(XBT_NIL, dev->nodename,
1029 info->dev_state_path,
1030 "%d", XenbusStateClosed);
1031 }
1032 break;
1033 case VSCSIFRONT_OP_DEL_LUN:
1034 if (device_state != XenbusStateClosing)
1035 break;
1036
1037 sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1038 if (sdev) {
1039 scsi_remove_device(sdev);
1040 scsi_device_put(sdev);
1041 }
1042 break;
1043 case VSCSIFRONT_OP_READD_LUN:
1044 if (device_state == XenbusStateConnected)
1045 xenbus_printf(XBT_NIL, dev->nodename,
1046 info->dev_state_path,
1047 "%d", XenbusStateConnected);
1048 break;
1049 default:
1050 break;
1051 }
1052 }
1053
1054 info->curr = NULL;
1055
1056 kfree(dir);
1057 }
1058
1059 static void scsifront_read_backend_params(struct xenbus_device *dev,
1060 struct vscsifrnt_info *info)
1061 {
1062 unsigned int sg_grant, nr_segs;
1063 int ret;
1064 struct Scsi_Host *host = info->host;
1065
1066 ret = xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg-grant", "%u",
1067 &sg_grant);
1068 if (ret != 1)
1069 sg_grant = 0;
1070 nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1071 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1072 nr_segs = min_t(unsigned int, nr_segs,
1073 VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1074 sizeof(struct scsiif_request_segment));
1075
1076 if (!info->pause && sg_grant)
1077 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1078 else if (info->pause && nr_segs < host->sg_tablesize)
1079 dev_warn(&dev->dev,
1080 "SG entries decreased from %d to %u - device may not work properly anymore\n",
1081 host->sg_tablesize, nr_segs);
1082
1083 host->sg_tablesize = nr_segs;
1084 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1085 }
1086
1087 static void scsifront_backend_changed(struct xenbus_device *dev,
1088 enum xenbus_state backend_state)
1089 {
1090 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1091
1092 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1093
1094 switch (backend_state) {
1095 case XenbusStateUnknown:
1096 case XenbusStateInitialising:
1097 case XenbusStateInitWait:
1098 case XenbusStateInitialised:
1099 break;
1100
1101 case XenbusStateConnected:
1102 scsifront_read_backend_params(dev, info);
1103
1104 if (info->pause) {
1105 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1106 xenbus_switch_state(dev, XenbusStateConnected);
1107 info->pause = 0;
1108 return;
1109 }
1110
1111 if (xenbus_read_driver_state(dev->nodename) ==
1112 XenbusStateInitialised)
1113 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1114
1115 if (dev->state != XenbusStateConnected)
1116 xenbus_switch_state(dev, XenbusStateConnected);
1117 break;
1118
1119 case XenbusStateClosed:
1120 if (dev->state == XenbusStateClosed)
1121 break;
1122 /* Missed the backend's Closing state -- fallthrough */
1123 case XenbusStateClosing:
1124 scsifront_disconnect(info);
1125 break;
1126
1127 case XenbusStateReconfiguring:
1128 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1129 xenbus_switch_state(dev, XenbusStateReconfiguring);
1130 break;
1131
1132 case XenbusStateReconfigured:
1133 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1134 xenbus_switch_state(dev, XenbusStateConnected);
1135 break;
1136 }
1137 }
1138
1139 static const struct xenbus_device_id scsifront_ids[] = {
1140 { "vscsi" },
1141 { "" }
1142 };
1143
1144 static struct xenbus_driver scsifront_driver = {
1145 .ids = scsifront_ids,
1146 .probe = scsifront_probe,
1147 .remove = scsifront_remove,
1148 .resume = scsifront_resume,
1149 .suspend = scsifront_suspend,
1150 .otherend_changed = scsifront_backend_changed,
1151 };
1152
1153 static int __init scsifront_init(void)
1154 {
1155 if (!xen_domain())
1156 return -ENODEV;
1157
1158 return xenbus_register_frontend(&scsifront_driver);
1159 }
1160 module_init(scsifront_init);
1161
1162 static void __exit scsifront_exit(void)
1163 {
1164 xenbus_unregister_driver(&scsifront_driver);
1165 }
1166 module_exit(scsifront_exit);
1167
1168 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1169 MODULE_LICENSE("GPL");
1170 MODULE_ALIAS("xen:vscsi");
1171 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
(deprecated) Btrfs devel tree