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4d05a28d KRW |
1 | /****************************************************************************** |
2 | * arch/xen/drivers/blkif/backend/main.c | |
3 | * | |
4 | * Back-end of the driver for virtual block devices. This portion of the | |
5 | * driver exports a 'unified' block-device interface that can be accessed | |
6 | * by any operating system that implements a compatible front end. A | |
7 | * reference front-end implementation can be found in: | |
8 | * arch/xen/drivers/blkif/frontend | |
9 | * | |
10 | * Copyright (c) 2003-2004, Keir Fraser & Steve Hand | |
11 | * Copyright (c) 2005, Christopher Clark | |
12 | * | |
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: | |
18 | * | |
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: | |
25 | * | |
26 | * The above copyright notice and this permission notice shall be included in | |
27 | * all copies or substantial portions of the Software. | |
28 | * | |
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 | |
35 | * IN THE SOFTWARE. | |
36 | */ | |
37 | ||
38 | #include <linux/spinlock.h> | |
39 | #include <linux/kthread.h> | |
40 | #include <linux/list.h> | |
41 | #include <linux/delay.h> | |
88122933 | 42 | #include <linux/freezer.h> |
afd91d07 | 43 | |
88122933 JF |
44 | #include <xen/events.h> |
45 | #include <xen/page.h> | |
46 | #include <asm/xen/hypervisor.h> | |
47 | #include <asm/xen/hypercall.h> | |
4d05a28d KRW |
48 | #include "common.h" |
49 | ||
50 | /* | |
51 | * These are rather arbitrary. They are fairly large because adjacent requests | |
52 | * pulled from a communication ring are quite likely to end up being part of | |
53 | * the same scatter/gather request at the disc. | |
54 | * | |
55 | * ** TRY INCREASING 'blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW ** | |
56 | * | |
57 | * This will increase the chances of being able to write whole tracks. | |
58 | * 64 should be enough to keep us competitive with Linux. | |
59 | */ | |
60 | static int blkif_reqs = 64; | |
61 | module_param_named(reqs, blkif_reqs, int, 0); | |
62 | MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate"); | |
63 | ||
64 | /* Run-time switchable: /sys/module/blkback/parameters/ */ | |
65 | static unsigned int log_stats = 0; | |
66 | static unsigned int debug_lvl = 0; | |
67 | module_param(log_stats, int, 0644); | |
68 | module_param(debug_lvl, int, 0644); | |
69 | ||
70 | /* | |
71 | * Each outstanding request that we've passed to the lower device layers has a | |
72 | * 'pending_req' allocated to it. Each buffer_head that completes decrements | |
73 | * the pendcnt towards zero. When it hits zero, the specified domain has a | |
74 | * response queued for it, with the saved 'id' passed back. | |
75 | */ | |
76 | typedef struct { | |
77 | blkif_t *blkif; | |
78 | u64 id; | |
79 | int nr_pages; | |
80 | atomic_t pendcnt; | |
81 | unsigned short operation; | |
82 | int status; | |
83 | struct list_head free_list; | |
84 | } pending_req_t; | |
85 | ||
4d05a28d KRW |
86 | #define BLKBACK_INVALID_HANDLE (~0) |
87 | ||
e8e28871 KRW |
88 | struct xen_blkbk { |
89 | pending_req_t *pending_reqs; | |
90 | struct list_head pending_free; | |
91 | spinlock_t pending_free_lock; | |
92 | wait_queue_head_t pending_free_wq; | |
93 | struct page **pending_pages; | |
94 | grant_handle_t *pending_grant_handles; | |
95 | }; | |
96 | ||
97 | static struct xen_blkbk *blkbk; | |
4d05a28d KRW |
98 | |
99 | static inline int vaddr_pagenr(pending_req_t *req, int seg) | |
100 | { | |
e8e28871 | 101 | return (req - blkbk->pending_reqs) * BLKIF_MAX_SEGMENTS_PER_REQUEST + seg; |
4d05a28d KRW |
102 | } |
103 | ||
efe08a3e JB |
104 | #define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)] |
105 | ||
4d05a28d KRW |
106 | static inline unsigned long vaddr(pending_req_t *req, int seg) |
107 | { | |
e8e28871 | 108 | unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg)); |
4d05a28d KRW |
109 | return (unsigned long)pfn_to_kaddr(pfn); |
110 | } | |
111 | ||
112 | #define pending_handle(_req, _seg) \ | |
e8e28871 | 113 | (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)]) |
4d05a28d KRW |
114 | |
115 | ||
116 | static int do_block_io_op(blkif_t *blkif); | |
117 | static void dispatch_rw_block_io(blkif_t *blkif, | |
88122933 | 118 | struct blkif_request *req, |
4d05a28d KRW |
119 | pending_req_t *pending_req); |
120 | static void make_response(blkif_t *blkif, u64 id, | |
121 | unsigned short op, int st); | |
122 | ||
123 | /****************************************************************** | |
124 | * misc small helpers | |
125 | */ | |
126 | static pending_req_t* alloc_req(void) | |
127 | { | |
128 | pending_req_t *req = NULL; | |
129 | unsigned long flags; | |
130 | ||
e8e28871 KRW |
131 | spin_lock_irqsave(&blkbk->pending_free_lock, flags); |
132 | if (!list_empty(&blkbk->pending_free)) { | |
133 | req = list_entry(blkbk->pending_free.next, pending_req_t, free_list); | |
4d05a28d KRW |
134 | list_del(&req->free_list); |
135 | } | |
e8e28871 | 136 | spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); |
4d05a28d KRW |
137 | return req; |
138 | } | |
139 | ||
140 | static void free_req(pending_req_t *req) | |
141 | { | |
142 | unsigned long flags; | |
143 | int was_empty; | |
144 | ||
e8e28871 KRW |
145 | spin_lock_irqsave(&blkbk->pending_free_lock, flags); |
146 | was_empty = list_empty(&blkbk->pending_free); | |
147 | list_add(&req->free_list, &blkbk->pending_free); | |
148 | spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); | |
4d05a28d | 149 | if (was_empty) |
e8e28871 | 150 | wake_up(&blkbk->pending_free_wq); |
4d05a28d KRW |
151 | } |
152 | ||
153 | static void unplug_queue(blkif_t *blkif) | |
154 | { | |
155 | if (blkif->plug == NULL) | |
156 | return; | |
157 | if (blkif->plug->unplug_fn) | |
158 | blkif->plug->unplug_fn(blkif->plug); | |
159 | blk_put_queue(blkif->plug); | |
160 | blkif->plug = NULL; | |
161 | } | |
162 | ||
163 | static void plug_queue(blkif_t *blkif, struct block_device *bdev) | |
164 | { | |
88122933 | 165 | struct request_queue *q = bdev_get_queue(bdev); |
4d05a28d KRW |
166 | |
167 | if (q == blkif->plug) | |
168 | return; | |
169 | unplug_queue(blkif); | |
170 | blk_get_queue(q); | |
171 | blkif->plug = q; | |
172 | } | |
173 | ||
174 | static void fast_flush_area(pending_req_t *req) | |
175 | { | |
176 | struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
177 | unsigned int i, invcount = 0; | |
178 | grant_handle_t handle; | |
179 | int ret; | |
180 | ||
181 | for (i = 0; i < req->nr_pages; i++) { | |
182 | handle = pending_handle(req, i); | |
183 | if (handle == BLKBACK_INVALID_HANDLE) | |
184 | continue; | |
185 | gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i), | |
186 | GNTMAP_host_map, handle); | |
187 | pending_handle(req, i) = BLKBACK_INVALID_HANDLE; | |
188 | invcount++; | |
189 | } | |
190 | ||
191 | ret = HYPERVISOR_grant_table_op( | |
192 | GNTTABOP_unmap_grant_ref, unmap, invcount); | |
193 | BUG_ON(ret); | |
5dc03639 KRW |
194 | /* Note, we use invcount, so nr->pages, so we can't index |
195 | * using vaddr(req, i). */ | |
196 | for (i = 0; i < invcount; i++) { | |
197 | ret = m2p_remove_override( | |
198 | virt_to_page(unmap[i].host_addr), false); | |
199 | if (ret) { | |
200 | printk(KERN_ALERT "Failed to remove M2P override for " \ | |
201 | "%lx\n", (unsigned long)unmap[i].host_addr); | |
202 | continue; | |
203 | } | |
204 | } | |
4d05a28d KRW |
205 | } |
206 | ||
207 | /****************************************************************** | |
208 | * SCHEDULER FUNCTIONS | |
209 | */ | |
210 | ||
211 | static void print_stats(blkif_t *blkif) | |
212 | { | |
213 | printk(KERN_DEBUG "%s: oo %3d | rd %4d | wr %4d | br %4d\n", | |
214 | current->comm, blkif->st_oo_req, | |
215 | blkif->st_rd_req, blkif->st_wr_req, blkif->st_br_req); | |
216 | blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); | |
217 | blkif->st_rd_req = 0; | |
218 | blkif->st_wr_req = 0; | |
219 | blkif->st_oo_req = 0; | |
220 | } | |
221 | ||
222 | int blkif_schedule(void *arg) | |
223 | { | |
224 | blkif_t *blkif = arg; | |
2ccbfe26 | 225 | struct vbd *vbd = &blkif->vbd; |
4d05a28d KRW |
226 | |
227 | blkif_get(blkif); | |
228 | ||
229 | if (debug_lvl) | |
230 | printk(KERN_DEBUG "%s: started\n", current->comm); | |
231 | ||
232 | while (!kthread_should_stop()) { | |
233 | if (try_to_freeze()) | |
234 | continue; | |
2ccbfe26 S |
235 | if (unlikely(vbd->size != vbd_size(vbd))) |
236 | vbd_resize(blkif); | |
4d05a28d KRW |
237 | |
238 | wait_event_interruptible( | |
239 | blkif->wq, | |
240 | blkif->waiting_reqs || kthread_should_stop()); | |
241 | wait_event_interruptible( | |
e8e28871 KRW |
242 | blkbk->pending_free_wq, |
243 | !list_empty(&blkbk->pending_free) || kthread_should_stop()); | |
4d05a28d KRW |
244 | |
245 | blkif->waiting_reqs = 0; | |
246 | smp_mb(); /* clear flag *before* checking for work */ | |
247 | ||
248 | if (do_block_io_op(blkif)) | |
249 | blkif->waiting_reqs = 1; | |
250 | unplug_queue(blkif); | |
251 | ||
252 | if (log_stats && time_after(jiffies, blkif->st_print)) | |
253 | print_stats(blkif); | |
254 | } | |
255 | ||
256 | if (log_stats) | |
257 | print_stats(blkif); | |
258 | if (debug_lvl) | |
259 | printk(KERN_DEBUG "%s: exiting\n", current->comm); | |
260 | ||
261 | blkif->xenblkd = NULL; | |
262 | blkif_put(blkif); | |
263 | ||
264 | return 0; | |
265 | } | |
266 | ||
267 | /****************************************************************** | |
268 | * COMPLETION CALLBACK -- Called as bh->b_end_io() | |
269 | */ | |
270 | ||
271 | static void __end_block_io_op(pending_req_t *pending_req, int error) | |
272 | { | |
273 | /* An error fails the entire request. */ | |
274 | if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && | |
275 | (error == -EOPNOTSUPP)) { | |
276 | DPRINTK("blkback: write barrier op failed, not supported\n"); | |
277 | blkback_barrier(XBT_NIL, pending_req->blkif->be, 0); | |
278 | pending_req->status = BLKIF_RSP_EOPNOTSUPP; | |
279 | } else if (error) { | |
280 | DPRINTK("Buffer not up-to-date at end of operation, " | |
281 | "error=%d\n", error); | |
282 | pending_req->status = BLKIF_RSP_ERROR; | |
283 | } | |
284 | ||
285 | if (atomic_dec_and_test(&pending_req->pendcnt)) { | |
286 | fast_flush_area(pending_req); | |
287 | make_response(pending_req->blkif, pending_req->id, | |
288 | pending_req->operation, pending_req->status); | |
289 | blkif_put(pending_req->blkif); | |
290 | free_req(pending_req); | |
291 | } | |
292 | } | |
293 | ||
88122933 | 294 | static void end_block_io_op(struct bio *bio, int error) |
4d05a28d | 295 | { |
4d05a28d KRW |
296 | __end_block_io_op(bio->bi_private, error); |
297 | bio_put(bio); | |
4d05a28d KRW |
298 | } |
299 | ||
300 | ||
301 | /****************************************************************************** | |
302 | * NOTIFICATION FROM GUEST OS. | |
303 | */ | |
304 | ||
305 | static void blkif_notify_work(blkif_t *blkif) | |
306 | { | |
307 | blkif->waiting_reqs = 1; | |
308 | wake_up(&blkif->wq); | |
309 | } | |
310 | ||
88122933 | 311 | irqreturn_t blkif_be_int(int irq, void *dev_id) |
4d05a28d KRW |
312 | { |
313 | blkif_notify_work(dev_id); | |
314 | return IRQ_HANDLED; | |
315 | } | |
316 | ||
317 | ||
318 | ||
319 | /****************************************************************** | |
320 | * DOWNWARD CALLS -- These interface with the block-device layer proper. | |
321 | */ | |
322 | ||
323 | static int do_block_io_op(blkif_t *blkif) | |
324 | { | |
88122933 JF |
325 | union blkif_back_rings *blk_rings = &blkif->blk_rings; |
326 | struct blkif_request req; | |
4d05a28d KRW |
327 | pending_req_t *pending_req; |
328 | RING_IDX rc, rp; | |
329 | int more_to_do = 0; | |
330 | ||
331 | rc = blk_rings->common.req_cons; | |
332 | rp = blk_rings->common.sring->req_prod; | |
333 | rmb(); /* Ensure we see queued requests up to 'rp'. */ | |
334 | ||
335 | while (rc != rp) { | |
336 | ||
337 | if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) | |
338 | break; | |
339 | ||
8270b45b | 340 | if (kthread_should_stop()) { |
4d05a28d KRW |
341 | more_to_do = 1; |
342 | break; | |
343 | } | |
344 | ||
8270b45b KF |
345 | pending_req = alloc_req(); |
346 | if (NULL == pending_req) { | |
347 | blkif->st_oo_req++; | |
4d05a28d KRW |
348 | more_to_do = 1; |
349 | break; | |
350 | } | |
351 | ||
352 | switch (blkif->blk_protocol) { | |
353 | case BLKIF_PROTOCOL_NATIVE: | |
354 | memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); | |
355 | break; | |
356 | case BLKIF_PROTOCOL_X86_32: | |
357 | blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); | |
358 | break; | |
359 | case BLKIF_PROTOCOL_X86_64: | |
360 | blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); | |
361 | break; | |
362 | default: | |
363 | BUG(); | |
364 | } | |
365 | blk_rings->common.req_cons = ++rc; /* before make_response() */ | |
366 | ||
367 | /* Apply all sanity checks to /private copy/ of request. */ | |
368 | barrier(); | |
369 | ||
370 | switch (req.operation) { | |
371 | case BLKIF_OP_READ: | |
372 | blkif->st_rd_req++; | |
373 | dispatch_rw_block_io(blkif, &req, pending_req); | |
374 | break; | |
375 | case BLKIF_OP_WRITE_BARRIER: | |
376 | blkif->st_br_req++; | |
377 | /* fall through */ | |
378 | case BLKIF_OP_WRITE: | |
379 | blkif->st_wr_req++; | |
380 | dispatch_rw_block_io(blkif, &req, pending_req); | |
381 | break; | |
382 | default: | |
383 | /* A good sign something is wrong: sleep for a while to | |
384 | * avoid excessive CPU consumption by a bad guest. */ | |
385 | msleep(1); | |
386 | DPRINTK("error: unknown block io operation [%d]\n", | |
387 | req.operation); | |
388 | make_response(blkif, req.id, req.operation, | |
389 | BLKIF_RSP_ERROR); | |
390 | free_req(pending_req); | |
391 | break; | |
392 | } | |
393 | ||
394 | /* Yield point for this unbounded loop. */ | |
395 | cond_resched(); | |
396 | } | |
397 | ||
398 | return more_to_do; | |
399 | } | |
400 | ||
401 | static void dispatch_rw_block_io(blkif_t *blkif, | |
88122933 | 402 | struct blkif_request *req, |
4d05a28d KRW |
403 | pending_req_t *pending_req) |
404 | { | |
4d05a28d KRW |
405 | struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; |
406 | struct phys_req preq; | |
407 | struct { | |
408 | unsigned long buf; unsigned int nsec; | |
409 | } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
410 | unsigned int nseg; | |
411 | struct bio *bio = NULL; | |
412 | int ret, i; | |
413 | int operation; | |
414 | ||
415 | switch (req->operation) { | |
416 | case BLKIF_OP_READ: | |
417 | operation = READ; | |
418 | break; | |
419 | case BLKIF_OP_WRITE: | |
420 | operation = WRITE; | |
421 | break; | |
422 | case BLKIF_OP_WRITE_BARRIER: | |
248e9f75 | 423 | operation = REQ_FLUSH | REQ_FUA; |
4d05a28d KRW |
424 | break; |
425 | default: | |
426 | operation = 0; /* make gcc happy */ | |
427 | BUG(); | |
428 | } | |
429 | ||
430 | /* Check that number of segments is sane. */ | |
431 | nseg = req->nr_segments; | |
248e9f75 | 432 | if (unlikely(nseg == 0 && operation != (REQ_FLUSH | REQ_FUA)) || |
4d05a28d KRW |
433 | unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) { |
434 | DPRINTK("Bad number of segments in request (%d)\n", nseg); | |
435 | goto fail_response; | |
436 | } | |
437 | ||
438 | preq.dev = req->handle; | |
c35950bf | 439 | preq.sector_number = req->u.rw.sector_number; |
4d05a28d KRW |
440 | preq.nr_sects = 0; |
441 | ||
442 | pending_req->blkif = blkif; | |
443 | pending_req->id = req->id; | |
444 | pending_req->operation = req->operation; | |
445 | pending_req->status = BLKIF_RSP_OKAY; | |
446 | pending_req->nr_pages = nseg; | |
447 | ||
448 | for (i = 0; i < nseg; i++) { | |
449 | uint32_t flags; | |
450 | ||
c35950bf KRW |
451 | seg[i].nsec = req->u.rw.seg[i].last_sect - |
452 | req->u.rw.seg[i].first_sect + 1; | |
4d05a28d | 453 | |
c35950bf KRW |
454 | if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || |
455 | (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect)) | |
4d05a28d KRW |
456 | goto fail_response; |
457 | preq.nr_sects += seg[i].nsec; | |
458 | ||
459 | flags = GNTMAP_host_map; | |
460 | if (operation != READ) | |
461 | flags |= GNTMAP_readonly; | |
462 | gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags, | |
c35950bf | 463 | req->u.rw.seg[i].gref, blkif->domid); |
4d05a28d KRW |
464 | } |
465 | ||
466 | ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg); | |
467 | BUG_ON(ret); | |
468 | ||
469 | for (i = 0; i < nseg; i++) { | |
470 | if (unlikely(map[i].status != 0)) { | |
471 | DPRINTK("invalid buffer -- could not remap it\n"); | |
472 | map[i].handle = BLKBACK_INVALID_HANDLE; | |
473 | ret |= 1; | |
474 | } | |
475 | ||
476 | pending_handle(pending_req, i) = map[i].handle; | |
477 | ||
478 | if (ret) | |
479 | continue; | |
5dc03639 KRW |
480 | |
481 | ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr), | |
482 | blkbk->pending_page(pending_req, i), false); | |
483 | if (ret) { | |
484 | printk(KERN_ALERT "Failed to install M2P override for"\ | |
485 | " %lx (ret: %d)\n", (unsigned long)map[i].dev_bus_addr, ret); | |
486 | continue; | |
487 | } | |
4d05a28d | 488 | |
4d05a28d | 489 | seg[i].buf = map[i].dev_bus_addr | |
c35950bf | 490 | (req->u.rw.seg[i].first_sect << 9); |
4d05a28d KRW |
491 | } |
492 | ||
493 | if (ret) | |
494 | goto fail_flush; | |
495 | ||
496 | if (vbd_translate(&preq, blkif, operation) != 0) { | |
497 | DPRINTK("access denied: %s of [%llu,%llu] on dev=%04x\n", | |
498 | operation == READ ? "read" : "write", | |
499 | preq.sector_number, | |
500 | preq.sector_number + preq.nr_sects, preq.dev); | |
501 | goto fail_flush; | |
502 | } | |
503 | ||
504 | plug_queue(blkif, preq.bdev); | |
505 | atomic_set(&pending_req->pendcnt, 1); | |
506 | blkif_get(blkif); | |
507 | ||
508 | for (i = 0; i < nseg; i++) { | |
509 | if (((int)preq.sector_number|(int)seg[i].nsec) & | |
05d43865 | 510 | ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { |
4d05a28d KRW |
511 | DPRINTK("Misaligned I/O request from domain %d", |
512 | blkif->domid); | |
513 | goto fail_put_bio; | |
514 | } | |
515 | ||
516 | while ((bio == NULL) || | |
517 | (bio_add_page(bio, | |
e8e28871 | 518 | blkbk->pending_page(pending_req, i), |
4d05a28d KRW |
519 | seg[i].nsec << 9, |
520 | seg[i].buf & ~PAGE_MASK) == 0)) { | |
521 | if (bio) { | |
522 | atomic_inc(&pending_req->pendcnt); | |
523 | submit_bio(operation, bio); | |
524 | } | |
525 | ||
526 | bio = bio_alloc(GFP_KERNEL, nseg-i); | |
527 | if (unlikely(bio == NULL)) | |
528 | goto fail_put_bio; | |
529 | ||
530 | bio->bi_bdev = preq.bdev; | |
531 | bio->bi_private = pending_req; | |
532 | bio->bi_end_io = end_block_io_op; | |
533 | bio->bi_sector = preq.sector_number; | |
534 | } | |
535 | ||
536 | preq.sector_number += seg[i].nsec; | |
537 | } | |
538 | ||
539 | if (!bio) { | |
248e9f75 | 540 | BUG_ON(operation != (REQ_FLUSH | REQ_FUA)); |
4d05a28d KRW |
541 | bio = bio_alloc(GFP_KERNEL, 0); |
542 | if (unlikely(bio == NULL)) | |
543 | goto fail_put_bio; | |
544 | ||
545 | bio->bi_bdev = preq.bdev; | |
546 | bio->bi_private = pending_req; | |
547 | bio->bi_end_io = end_block_io_op; | |
548 | bio->bi_sector = -1; | |
549 | } | |
550 | ||
551 | submit_bio(operation, bio); | |
552 | ||
553 | if (operation == READ) | |
554 | blkif->st_rd_sect += preq.nr_sects; | |
248e9f75 | 555 | else if (operation == WRITE || operation == (REQ_FLUSH | REQ_FUA)) |
4d05a28d KRW |
556 | blkif->st_wr_sect += preq.nr_sects; |
557 | ||
558 | return; | |
559 | ||
560 | fail_flush: | |
561 | fast_flush_area(pending_req); | |
562 | fail_response: | |
563 | make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR); | |
564 | free_req(pending_req); | |
565 | msleep(1); /* back off a bit */ | |
566 | return; | |
567 | ||
568 | fail_put_bio: | |
569 | __end_block_io_op(pending_req, -EINVAL); | |
570 | if (bio) | |
571 | bio_put(bio); | |
572 | unplug_queue(blkif); | |
573 | msleep(1); /* back off a bit */ | |
574 | return; | |
575 | } | |
576 | ||
577 | ||
578 | ||
579 | /****************************************************************** | |
580 | * MISCELLANEOUS SETUP / TEARDOWN / DEBUGGING | |
581 | */ | |
582 | ||
583 | ||
584 | static void make_response(blkif_t *blkif, u64 id, | |
585 | unsigned short op, int st) | |
586 | { | |
88122933 | 587 | struct blkif_response resp; |
4d05a28d | 588 | unsigned long flags; |
88122933 | 589 | union blkif_back_rings *blk_rings = &blkif->blk_rings; |
4d05a28d KRW |
590 | int more_to_do = 0; |
591 | int notify; | |
592 | ||
593 | resp.id = id; | |
594 | resp.operation = op; | |
595 | resp.status = st; | |
596 | ||
597 | spin_lock_irqsave(&blkif->blk_ring_lock, flags); | |
598 | /* Place on the response ring for the relevant domain. */ | |
599 | switch (blkif->blk_protocol) { | |
600 | case BLKIF_PROTOCOL_NATIVE: | |
601 | memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), | |
602 | &resp, sizeof(resp)); | |
603 | break; | |
604 | case BLKIF_PROTOCOL_X86_32: | |
605 | memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), | |
606 | &resp, sizeof(resp)); | |
607 | break; | |
608 | case BLKIF_PROTOCOL_X86_64: | |
609 | memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), | |
610 | &resp, sizeof(resp)); | |
611 | break; | |
612 | default: | |
613 | BUG(); | |
614 | } | |
615 | blk_rings->common.rsp_prod_pvt++; | |
616 | RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); | |
617 | if (blk_rings->common.rsp_prod_pvt == blk_rings->common.req_cons) { | |
618 | /* | |
619 | * Tail check for pending requests. Allows frontend to avoid | |
620 | * notifications if requests are already in flight (lower | |
621 | * overheads and promotes batching). | |
622 | */ | |
623 | RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); | |
624 | ||
625 | } else if (RING_HAS_UNCONSUMED_REQUESTS(&blk_rings->common)) { | |
626 | more_to_do = 1; | |
627 | } | |
628 | ||
629 | spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); | |
630 | ||
631 | if (more_to_do) | |
632 | blkif_notify_work(blkif); | |
633 | if (notify) | |
634 | notify_remote_via_irq(blkif->irq); | |
635 | } | |
636 | ||
637 | static int __init blkif_init(void) | |
638 | { | |
639 | int i, mmap_pages; | |
8770b268 | 640 | int rc = 0; |
4d05a28d | 641 | |
88122933 | 642 | if (!xen_pv_domain()) |
4d05a28d KRW |
643 | return -ENODEV; |
644 | ||
e8e28871 KRW |
645 | blkbk = (struct xen_blkbk *)vmalloc(sizeof(struct xen_blkbk)); |
646 | if (!blkbk) { | |
647 | printk(KERN_ALERT "%s: out of memory!\n", __func__); | |
648 | return -ENOMEM; | |
649 | } | |
650 | ||
4d05a28d KRW |
651 | mmap_pages = blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST; |
652 | ||
e8e28871 | 653 | blkbk->pending_reqs = kmalloc(sizeof(blkbk->pending_reqs[0]) * |
4d05a28d | 654 | blkif_reqs, GFP_KERNEL); |
464fb419 KRW |
655 | blkbk->pending_grant_handles = vzalloc(sizeof(blkbk->pending_grant_handles[0]) * |
656 | mmap_pages); | |
657 | blkbk->pending_pages = vzalloc(sizeof(blkbk->pending_pages[0]) * mmap_pages); | |
4d05a28d | 658 | |
e8e28871 | 659 | if (!blkbk->pending_reqs || !blkbk->pending_grant_handles || !blkbk->pending_pages) { |
8770b268 | 660 | rc = -ENOMEM; |
4d05a28d | 661 | goto out_of_memory; |
8770b268 | 662 | } |
4d05a28d | 663 | |
464fb419 | 664 | for (i = 0; i < mmap_pages; i++) { |
e8e28871 | 665 | blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE; |
464fb419 KRW |
666 | blkbk->pending_pages[i] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM); |
667 | if (blkbk->pending_pages[i] == NULL) { | |
668 | rc = -ENOMEM; | |
669 | goto out_of_memory; | |
670 | } | |
671 | } | |
8770b268 KRW |
672 | rc = blkif_interface_init(); |
673 | if (rc) | |
674 | goto failed_init; | |
4d05a28d | 675 | |
e8e28871 KRW |
676 | memset(blkbk->pending_reqs, 0, sizeof(blkbk->pending_reqs)); |
677 | ||
678 | INIT_LIST_HEAD(&blkbk->pending_free); | |
679 | spin_lock_init(&blkbk->pending_free_lock); | |
680 | init_waitqueue_head(&blkbk->pending_free_wq); | |
4d05a28d KRW |
681 | |
682 | for (i = 0; i < blkif_reqs; i++) | |
e8e28871 | 683 | list_add_tail(&blkbk->pending_reqs[i].free_list, &blkbk->pending_free); |
4d05a28d | 684 | |
8770b268 KRW |
685 | rc = blkif_xenbus_init(); |
686 | if (rc) | |
687 | goto failed_init; | |
4d05a28d KRW |
688 | |
689 | return 0; | |
690 | ||
691 | out_of_memory: | |
8770b268 KRW |
692 | printk(KERN_ERR "%s: out of memory\n", __func__); |
693 | failed_init: | |
e8e28871 | 694 | kfree(blkbk->pending_reqs); |
464fb419 KRW |
695 | vfree(blkbk->pending_grant_handles); |
696 | for (i = 0; i < mmap_pages; i++) { | |
697 | if (blkbk->pending_pages[i]) | |
698 | __free_page(blkbk->pending_pages[i]); | |
699 | } | |
700 | vfree(blkbk->pending_pages); | |
e8e28871 KRW |
701 | vfree(blkbk); |
702 | blkbk = NULL; | |
8770b268 | 703 | return rc; |
4d05a28d KRW |
704 | } |
705 | ||
706 | module_init(blkif_init); | |
707 | ||
708 | MODULE_LICENSE("Dual BSD/GPL"); |