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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 | #define pr_fmt(fmt) "xen-blkback: " fmt | |
38 | ||
39 | #include <linux/spinlock.h> | |
40 | #include <linux/kthread.h> | |
41 | #include <linux/list.h> | |
42 | #include <linux/delay.h> | |
43 | #include <linux/freezer.h> | |
44 | #include <linux/bitmap.h> | |
45 | ||
46 | #include <xen/events.h> | |
47 | #include <xen/page.h> | |
48 | #include <xen/xen.h> | |
49 | #include <asm/xen/hypervisor.h> | |
50 | #include <asm/xen/hypercall.h> | |
51 | #include <xen/balloon.h> | |
52 | #include <xen/grant_table.h> | |
53 | #include "common.h" | |
54 | ||
55 | /* | |
56 | * Maximum number of unused free pages to keep in the internal buffer. | |
57 | * Setting this to a value too low will reduce memory used in each backend, | |
58 | * but can have a performance penalty. | |
59 | * | |
60 | * A sane value is xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST, but can | |
61 | * be set to a lower value that might degrade performance on some intensive | |
62 | * IO workloads. | |
63 | */ | |
64 | ||
65 | static int xen_blkif_max_buffer_pages = 1024; | |
66 | module_param_named(max_buffer_pages, xen_blkif_max_buffer_pages, int, 0644); | |
67 | MODULE_PARM_DESC(max_buffer_pages, | |
68 | "Maximum number of free pages to keep in each block backend buffer"); | |
69 | ||
70 | /* | |
71 | * Maximum number of grants to map persistently in blkback. For maximum | |
72 | * performance this should be the total numbers of grants that can be used | |
73 | * to fill the ring, but since this might become too high, specially with | |
74 | * the use of indirect descriptors, we set it to a value that provides good | |
75 | * performance without using too much memory. | |
76 | * | |
77 | * When the list of persistent grants is full we clean it up using a LRU | |
78 | * algorithm. | |
79 | */ | |
80 | ||
81 | static int xen_blkif_max_pgrants = 1056; | |
82 | module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644); | |
83 | MODULE_PARM_DESC(max_persistent_grants, | |
84 | "Maximum number of grants to map persistently"); | |
85 | ||
86 | /* | |
87 | * Maximum order of pages to be used for the shared ring between front and | |
88 | * backend, 4KB page granularity is used. | |
89 | */ | |
90 | unsigned int xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER; | |
91 | module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO); | |
92 | MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); | |
93 | /* | |
94 | * The LRU mechanism to clean the lists of persistent grants needs to | |
95 | * be executed periodically. The time interval between consecutive executions | |
96 | * of the purge mechanism is set in ms. | |
97 | */ | |
98 | #define LRU_INTERVAL 100 | |
99 | ||
100 | /* | |
101 | * When the persistent grants list is full we will remove unused grants | |
102 | * from the list. The percent number of grants to be removed at each LRU | |
103 | * execution. | |
104 | */ | |
105 | #define LRU_PERCENT_CLEAN 5 | |
106 | ||
107 | /* Run-time switchable: /sys/module/blkback/parameters/ */ | |
108 | static unsigned int log_stats; | |
109 | module_param(log_stats, int, 0644); | |
110 | ||
111 | #define BLKBACK_INVALID_HANDLE (~0) | |
112 | ||
113 | /* Number of free pages to remove on each call to gnttab_free_pages */ | |
114 | #define NUM_BATCH_FREE_PAGES 10 | |
115 | ||
116 | static inline int get_free_page(struct xen_blkif *blkif, struct page **page) | |
117 | { | |
118 | unsigned long flags; | |
119 | ||
120 | spin_lock_irqsave(&blkif->free_pages_lock, flags); | |
121 | if (list_empty(&blkif->free_pages)) { | |
122 | BUG_ON(blkif->free_pages_num != 0); | |
123 | spin_unlock_irqrestore(&blkif->free_pages_lock, flags); | |
124 | return gnttab_alloc_pages(1, page); | |
125 | } | |
126 | BUG_ON(blkif->free_pages_num == 0); | |
127 | page[0] = list_first_entry(&blkif->free_pages, struct page, lru); | |
128 | list_del(&page[0]->lru); | |
129 | blkif->free_pages_num--; | |
130 | spin_unlock_irqrestore(&blkif->free_pages_lock, flags); | |
131 | ||
132 | return 0; | |
133 | } | |
134 | ||
135 | static inline void put_free_pages(struct xen_blkif *blkif, struct page **page, | |
136 | int num) | |
137 | { | |
138 | unsigned long flags; | |
139 | int i; | |
140 | ||
141 | spin_lock_irqsave(&blkif->free_pages_lock, flags); | |
142 | for (i = 0; i < num; i++) | |
143 | list_add(&page[i]->lru, &blkif->free_pages); | |
144 | blkif->free_pages_num += num; | |
145 | spin_unlock_irqrestore(&blkif->free_pages_lock, flags); | |
146 | } | |
147 | ||
148 | static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num) | |
149 | { | |
150 | /* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */ | |
151 | struct page *page[NUM_BATCH_FREE_PAGES]; | |
152 | unsigned int num_pages = 0; | |
153 | unsigned long flags; | |
154 | ||
155 | spin_lock_irqsave(&blkif->free_pages_lock, flags); | |
156 | while (blkif->free_pages_num > num) { | |
157 | BUG_ON(list_empty(&blkif->free_pages)); | |
158 | page[num_pages] = list_first_entry(&blkif->free_pages, | |
159 | struct page, lru); | |
160 | list_del(&page[num_pages]->lru); | |
161 | blkif->free_pages_num--; | |
162 | if (++num_pages == NUM_BATCH_FREE_PAGES) { | |
163 | spin_unlock_irqrestore(&blkif->free_pages_lock, flags); | |
164 | gnttab_free_pages(num_pages, page); | |
165 | spin_lock_irqsave(&blkif->free_pages_lock, flags); | |
166 | num_pages = 0; | |
167 | } | |
168 | } | |
169 | spin_unlock_irqrestore(&blkif->free_pages_lock, flags); | |
170 | if (num_pages != 0) | |
171 | gnttab_free_pages(num_pages, page); | |
172 | } | |
173 | ||
174 | #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page))) | |
175 | ||
176 | static int do_block_io_op(struct xen_blkif *blkif); | |
177 | static int dispatch_rw_block_io(struct xen_blkif *blkif, | |
178 | struct blkif_request *req, | |
179 | struct pending_req *pending_req); | |
180 | static void make_response(struct xen_blkif *blkif, u64 id, | |
181 | unsigned short op, int st); | |
182 | ||
183 | #define foreach_grant_safe(pos, n, rbtree, node) \ | |
184 | for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \ | |
185 | (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \ | |
186 | &(pos)->node != NULL; \ | |
187 | (pos) = container_of(n, typeof(*(pos)), node), \ | |
188 | (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL) | |
189 | ||
190 | ||
191 | /* | |
192 | * We don't need locking around the persistent grant helpers | |
193 | * because blkback uses a single-thread for each backed, so we | |
194 | * can be sure that this functions will never be called recursively. | |
195 | * | |
196 | * The only exception to that is put_persistent_grant, that can be called | |
197 | * from interrupt context (by xen_blkbk_unmap), so we have to use atomic | |
198 | * bit operations to modify the flags of a persistent grant and to count | |
199 | * the number of used grants. | |
200 | */ | |
201 | static int add_persistent_gnt(struct xen_blkif *blkif, | |
202 | struct persistent_gnt *persistent_gnt) | |
203 | { | |
204 | struct rb_node **new = NULL, *parent = NULL; | |
205 | struct persistent_gnt *this; | |
206 | ||
207 | if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) { | |
208 | if (!blkif->vbd.overflow_max_grants) | |
209 | blkif->vbd.overflow_max_grants = 1; | |
210 | return -EBUSY; | |
211 | } | |
212 | /* Figure out where to put new node */ | |
213 | new = &blkif->persistent_gnts.rb_node; | |
214 | while (*new) { | |
215 | this = container_of(*new, struct persistent_gnt, node); | |
216 | ||
217 | parent = *new; | |
218 | if (persistent_gnt->gnt < this->gnt) | |
219 | new = &((*new)->rb_left); | |
220 | else if (persistent_gnt->gnt > this->gnt) | |
221 | new = &((*new)->rb_right); | |
222 | else { | |
223 | pr_alert_ratelimited("trying to add a gref that's already in the tree\n"); | |
224 | return -EINVAL; | |
225 | } | |
226 | } | |
227 | ||
228 | bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE); | |
229 | set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); | |
230 | /* Add new node and rebalance tree. */ | |
231 | rb_link_node(&(persistent_gnt->node), parent, new); | |
232 | rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts); | |
233 | blkif->persistent_gnt_c++; | |
234 | atomic_inc(&blkif->persistent_gnt_in_use); | |
235 | return 0; | |
236 | } | |
237 | ||
238 | static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif, | |
239 | grant_ref_t gref) | |
240 | { | |
241 | struct persistent_gnt *data; | |
242 | struct rb_node *node = NULL; | |
243 | ||
244 | node = blkif->persistent_gnts.rb_node; | |
245 | while (node) { | |
246 | data = container_of(node, struct persistent_gnt, node); | |
247 | ||
248 | if (gref < data->gnt) | |
249 | node = node->rb_left; | |
250 | else if (gref > data->gnt) | |
251 | node = node->rb_right; | |
252 | else { | |
253 | if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) { | |
254 | pr_alert_ratelimited("requesting a grant already in use\n"); | |
255 | return NULL; | |
256 | } | |
257 | set_bit(PERSISTENT_GNT_ACTIVE, data->flags); | |
258 | atomic_inc(&blkif->persistent_gnt_in_use); | |
259 | return data; | |
260 | } | |
261 | } | |
262 | return NULL; | |
263 | } | |
264 | ||
265 | static void put_persistent_gnt(struct xen_blkif *blkif, | |
266 | struct persistent_gnt *persistent_gnt) | |
267 | { | |
268 | if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) | |
269 | pr_alert_ratelimited("freeing a grant already unused\n"); | |
270 | set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); | |
271 | clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); | |
272 | atomic_dec(&blkif->persistent_gnt_in_use); | |
273 | } | |
274 | ||
275 | static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root, | |
276 | unsigned int num) | |
277 | { | |
278 | struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
279 | struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
280 | struct persistent_gnt *persistent_gnt; | |
281 | struct rb_node *n; | |
282 | int segs_to_unmap = 0; | |
283 | struct gntab_unmap_queue_data unmap_data; | |
284 | ||
285 | unmap_data.pages = pages; | |
286 | unmap_data.unmap_ops = unmap; | |
287 | unmap_data.kunmap_ops = NULL; | |
288 | ||
289 | foreach_grant_safe(persistent_gnt, n, root, node) { | |
290 | BUG_ON(persistent_gnt->handle == | |
291 | BLKBACK_INVALID_HANDLE); | |
292 | gnttab_set_unmap_op(&unmap[segs_to_unmap], | |
293 | (unsigned long) pfn_to_kaddr(page_to_pfn( | |
294 | persistent_gnt->page)), | |
295 | GNTMAP_host_map, | |
296 | persistent_gnt->handle); | |
297 | ||
298 | pages[segs_to_unmap] = persistent_gnt->page; | |
299 | ||
300 | if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST || | |
301 | !rb_next(&persistent_gnt->node)) { | |
302 | ||
303 | unmap_data.count = segs_to_unmap; | |
304 | BUG_ON(gnttab_unmap_refs_sync(&unmap_data)); | |
305 | ||
306 | put_free_pages(blkif, pages, segs_to_unmap); | |
307 | segs_to_unmap = 0; | |
308 | } | |
309 | ||
310 | rb_erase(&persistent_gnt->node, root); | |
311 | kfree(persistent_gnt); | |
312 | num--; | |
313 | } | |
314 | BUG_ON(num != 0); | |
315 | } | |
316 | ||
317 | void xen_blkbk_unmap_purged_grants(struct work_struct *work) | |
318 | { | |
319 | struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
320 | struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
321 | struct persistent_gnt *persistent_gnt; | |
322 | int segs_to_unmap = 0; | |
323 | struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work); | |
324 | struct gntab_unmap_queue_data unmap_data; | |
325 | ||
326 | unmap_data.pages = pages; | |
327 | unmap_data.unmap_ops = unmap; | |
328 | unmap_data.kunmap_ops = NULL; | |
329 | ||
330 | while(!list_empty(&blkif->persistent_purge_list)) { | |
331 | persistent_gnt = list_first_entry(&blkif->persistent_purge_list, | |
332 | struct persistent_gnt, | |
333 | remove_node); | |
334 | list_del(&persistent_gnt->remove_node); | |
335 | ||
336 | gnttab_set_unmap_op(&unmap[segs_to_unmap], | |
337 | vaddr(persistent_gnt->page), | |
338 | GNTMAP_host_map, | |
339 | persistent_gnt->handle); | |
340 | ||
341 | pages[segs_to_unmap] = persistent_gnt->page; | |
342 | ||
343 | if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) { | |
344 | unmap_data.count = segs_to_unmap; | |
345 | BUG_ON(gnttab_unmap_refs_sync(&unmap_data)); | |
346 | put_free_pages(blkif, pages, segs_to_unmap); | |
347 | segs_to_unmap = 0; | |
348 | } | |
349 | kfree(persistent_gnt); | |
350 | } | |
351 | if (segs_to_unmap > 0) { | |
352 | unmap_data.count = segs_to_unmap; | |
353 | BUG_ON(gnttab_unmap_refs_sync(&unmap_data)); | |
354 | put_free_pages(blkif, pages, segs_to_unmap); | |
355 | } | |
356 | } | |
357 | ||
358 | static void purge_persistent_gnt(struct xen_blkif *blkif) | |
359 | { | |
360 | struct persistent_gnt *persistent_gnt; | |
361 | struct rb_node *n; | |
362 | unsigned int num_clean, total; | |
363 | bool scan_used = false, clean_used = false; | |
364 | struct rb_root *root; | |
365 | ||
366 | if (blkif->persistent_gnt_c < xen_blkif_max_pgrants || | |
367 | (blkif->persistent_gnt_c == xen_blkif_max_pgrants && | |
368 | !blkif->vbd.overflow_max_grants)) { | |
369 | return; | |
370 | } | |
371 | ||
372 | if (work_pending(&blkif->persistent_purge_work)) { | |
373 | pr_alert_ratelimited("Scheduled work from previous purge is still pending, cannot purge list\n"); | |
374 | return; | |
375 | } | |
376 | ||
377 | num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN; | |
378 | num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean; | |
379 | num_clean = min(blkif->persistent_gnt_c, num_clean); | |
380 | if ((num_clean == 0) || | |
381 | (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use)))) | |
382 | return; | |
383 | ||
384 | /* | |
385 | * At this point, we can assure that there will be no calls | |
386 | * to get_persistent_grant (because we are executing this code from | |
387 | * xen_blkif_schedule), there can only be calls to put_persistent_gnt, | |
388 | * which means that the number of currently used grants will go down, | |
389 | * but never up, so we will always be able to remove the requested | |
390 | * number of grants. | |
391 | */ | |
392 | ||
393 | total = num_clean; | |
394 | ||
395 | pr_debug("Going to purge %u persistent grants\n", num_clean); | |
396 | ||
397 | BUG_ON(!list_empty(&blkif->persistent_purge_list)); | |
398 | root = &blkif->persistent_gnts; | |
399 | purge_list: | |
400 | foreach_grant_safe(persistent_gnt, n, root, node) { | |
401 | BUG_ON(persistent_gnt->handle == | |
402 | BLKBACK_INVALID_HANDLE); | |
403 | ||
404 | if (clean_used) { | |
405 | clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); | |
406 | continue; | |
407 | } | |
408 | ||
409 | if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) | |
410 | continue; | |
411 | if (!scan_used && | |
412 | (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags))) | |
413 | continue; | |
414 | ||
415 | rb_erase(&persistent_gnt->node, root); | |
416 | list_add(&persistent_gnt->remove_node, | |
417 | &blkif->persistent_purge_list); | |
418 | if (--num_clean == 0) | |
419 | goto finished; | |
420 | } | |
421 | /* | |
422 | * If we get here it means we also need to start cleaning | |
423 | * grants that were used since last purge in order to cope | |
424 | * with the requested num | |
425 | */ | |
426 | if (!scan_used && !clean_used) { | |
427 | pr_debug("Still missing %u purged frames\n", num_clean); | |
428 | scan_used = true; | |
429 | goto purge_list; | |
430 | } | |
431 | finished: | |
432 | if (!clean_used) { | |
433 | pr_debug("Finished scanning for grants to clean, removing used flag\n"); | |
434 | clean_used = true; | |
435 | goto purge_list; | |
436 | } | |
437 | ||
438 | blkif->persistent_gnt_c -= (total - num_clean); | |
439 | blkif->vbd.overflow_max_grants = 0; | |
440 | ||
441 | /* We can defer this work */ | |
442 | schedule_work(&blkif->persistent_purge_work); | |
443 | pr_debug("Purged %u/%u\n", (total - num_clean), total); | |
444 | return; | |
445 | } | |
446 | ||
447 | /* | |
448 | * Retrieve from the 'pending_reqs' a free pending_req structure to be used. | |
449 | */ | |
450 | static struct pending_req *alloc_req(struct xen_blkif *blkif) | |
451 | { | |
452 | struct pending_req *req = NULL; | |
453 | unsigned long flags; | |
454 | ||
455 | spin_lock_irqsave(&blkif->pending_free_lock, flags); | |
456 | if (!list_empty(&blkif->pending_free)) { | |
457 | req = list_entry(blkif->pending_free.next, struct pending_req, | |
458 | free_list); | |
459 | list_del(&req->free_list); | |
460 | } | |
461 | spin_unlock_irqrestore(&blkif->pending_free_lock, flags); | |
462 | return req; | |
463 | } | |
464 | ||
465 | /* | |
466 | * Return the 'pending_req' structure back to the freepool. We also | |
467 | * wake up the thread if it was waiting for a free page. | |
468 | */ | |
469 | static void free_req(struct xen_blkif *blkif, struct pending_req *req) | |
470 | { | |
471 | unsigned long flags; | |
472 | int was_empty; | |
473 | ||
474 | spin_lock_irqsave(&blkif->pending_free_lock, flags); | |
475 | was_empty = list_empty(&blkif->pending_free); | |
476 | list_add(&req->free_list, &blkif->pending_free); | |
477 | spin_unlock_irqrestore(&blkif->pending_free_lock, flags); | |
478 | if (was_empty) | |
479 | wake_up(&blkif->pending_free_wq); | |
480 | } | |
481 | ||
482 | /* | |
483 | * Routines for managing virtual block devices (vbds). | |
484 | */ | |
485 | static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, | |
486 | int operation) | |
487 | { | |
488 | struct xen_vbd *vbd = &blkif->vbd; | |
489 | int rc = -EACCES; | |
490 | ||
491 | if ((operation != READ) && vbd->readonly) | |
492 | goto out; | |
493 | ||
494 | if (likely(req->nr_sects)) { | |
495 | blkif_sector_t end = req->sector_number + req->nr_sects; | |
496 | ||
497 | if (unlikely(end < req->sector_number)) | |
498 | goto out; | |
499 | if (unlikely(end > vbd_sz(vbd))) | |
500 | goto out; | |
501 | } | |
502 | ||
503 | req->dev = vbd->pdevice; | |
504 | req->bdev = vbd->bdev; | |
505 | rc = 0; | |
506 | ||
507 | out: | |
508 | return rc; | |
509 | } | |
510 | ||
511 | static void xen_vbd_resize(struct xen_blkif *blkif) | |
512 | { | |
513 | struct xen_vbd *vbd = &blkif->vbd; | |
514 | struct xenbus_transaction xbt; | |
515 | int err; | |
516 | struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); | |
517 | unsigned long long new_size = vbd_sz(vbd); | |
518 | ||
519 | pr_info("VBD Resize: Domid: %d, Device: (%d, %d)\n", | |
520 | blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); | |
521 | pr_info("VBD Resize: new size %llu\n", new_size); | |
522 | vbd->size = new_size; | |
523 | again: | |
524 | err = xenbus_transaction_start(&xbt); | |
525 | if (err) { | |
526 | pr_warn("Error starting transaction\n"); | |
527 | return; | |
528 | } | |
529 | err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", | |
530 | (unsigned long long)vbd_sz(vbd)); | |
531 | if (err) { | |
532 | pr_warn("Error writing new size\n"); | |
533 | goto abort; | |
534 | } | |
535 | /* | |
536 | * Write the current state; we will use this to synchronize | |
537 | * the front-end. If the current state is "connected" the | |
538 | * front-end will get the new size information online. | |
539 | */ | |
540 | err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); | |
541 | if (err) { | |
542 | pr_warn("Error writing the state\n"); | |
543 | goto abort; | |
544 | } | |
545 | ||
546 | err = xenbus_transaction_end(xbt, 0); | |
547 | if (err == -EAGAIN) | |
548 | goto again; | |
549 | if (err) | |
550 | pr_warn("Error ending transaction\n"); | |
551 | return; | |
552 | abort: | |
553 | xenbus_transaction_end(xbt, 1); | |
554 | } | |
555 | ||
556 | /* | |
557 | * Notification from the guest OS. | |
558 | */ | |
559 | static void blkif_notify_work(struct xen_blkif *blkif) | |
560 | { | |
561 | blkif->waiting_reqs = 1; | |
562 | wake_up(&blkif->wq); | |
563 | } | |
564 | ||
565 | irqreturn_t xen_blkif_be_int(int irq, void *dev_id) | |
566 | { | |
567 | blkif_notify_work(dev_id); | |
568 | return IRQ_HANDLED; | |
569 | } | |
570 | ||
571 | /* | |
572 | * SCHEDULER FUNCTIONS | |
573 | */ | |
574 | ||
575 | static void print_stats(struct xen_blkif *blkif) | |
576 | { | |
577 | pr_info("(%s): oo %3llu | rd %4llu | wr %4llu | f %4llu" | |
578 | " | ds %4llu | pg: %4u/%4d\n", | |
579 | current->comm, blkif->st_oo_req, | |
580 | blkif->st_rd_req, blkif->st_wr_req, | |
581 | blkif->st_f_req, blkif->st_ds_req, | |
582 | blkif->persistent_gnt_c, | |
583 | xen_blkif_max_pgrants); | |
584 | blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); | |
585 | blkif->st_rd_req = 0; | |
586 | blkif->st_wr_req = 0; | |
587 | blkif->st_oo_req = 0; | |
588 | blkif->st_ds_req = 0; | |
589 | } | |
590 | ||
591 | int xen_blkif_schedule(void *arg) | |
592 | { | |
593 | struct xen_blkif *blkif = arg; | |
594 | struct xen_vbd *vbd = &blkif->vbd; | |
595 | unsigned long timeout; | |
596 | int ret; | |
597 | ||
598 | xen_blkif_get(blkif); | |
599 | ||
600 | while (!kthread_should_stop()) { | |
601 | if (try_to_freeze()) | |
602 | continue; | |
603 | if (unlikely(vbd->size != vbd_sz(vbd))) | |
604 | xen_vbd_resize(blkif); | |
605 | ||
606 | timeout = msecs_to_jiffies(LRU_INTERVAL); | |
607 | ||
608 | timeout = wait_event_interruptible_timeout( | |
609 | blkif->wq, | |
610 | blkif->waiting_reqs || kthread_should_stop(), | |
611 | timeout); | |
612 | if (timeout == 0) | |
613 | goto purge_gnt_list; | |
614 | timeout = wait_event_interruptible_timeout( | |
615 | blkif->pending_free_wq, | |
616 | !list_empty(&blkif->pending_free) || | |
617 | kthread_should_stop(), | |
618 | timeout); | |
619 | if (timeout == 0) | |
620 | goto purge_gnt_list; | |
621 | ||
622 | blkif->waiting_reqs = 0; | |
623 | smp_mb(); /* clear flag *before* checking for work */ | |
624 | ||
625 | ret = do_block_io_op(blkif); | |
626 | if (ret > 0) | |
627 | blkif->waiting_reqs = 1; | |
628 | if (ret == -EACCES) | |
629 | wait_event_interruptible(blkif->shutdown_wq, | |
630 | kthread_should_stop()); | |
631 | ||
632 | purge_gnt_list: | |
633 | if (blkif->vbd.feature_gnt_persistent && | |
634 | time_after(jiffies, blkif->next_lru)) { | |
635 | purge_persistent_gnt(blkif); | |
636 | blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL); | |
637 | } | |
638 | ||
639 | /* Shrink if we have more than xen_blkif_max_buffer_pages */ | |
640 | shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages); | |
641 | ||
642 | if (log_stats && time_after(jiffies, blkif->st_print)) | |
643 | print_stats(blkif); | |
644 | } | |
645 | ||
646 | /* Drain pending purge work */ | |
647 | flush_work(&blkif->persistent_purge_work); | |
648 | ||
649 | if (log_stats) | |
650 | print_stats(blkif); | |
651 | ||
652 | blkif->xenblkd = NULL; | |
653 | xen_blkif_put(blkif); | |
654 | ||
655 | return 0; | |
656 | } | |
657 | ||
658 | /* | |
659 | * Remove persistent grants and empty the pool of free pages | |
660 | */ | |
661 | void xen_blkbk_free_caches(struct xen_blkif *blkif) | |
662 | { | |
663 | /* Free all persistent grant pages */ | |
664 | if (!RB_EMPTY_ROOT(&blkif->persistent_gnts)) | |
665 | free_persistent_gnts(blkif, &blkif->persistent_gnts, | |
666 | blkif->persistent_gnt_c); | |
667 | ||
668 | BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); | |
669 | blkif->persistent_gnt_c = 0; | |
670 | ||
671 | /* Since we are shutting down remove all pages from the buffer */ | |
672 | shrink_free_pagepool(blkif, 0 /* All */); | |
673 | } | |
674 | ||
675 | static unsigned int xen_blkbk_unmap_prepare( | |
676 | struct xen_blkif *blkif, | |
677 | struct grant_page **pages, | |
678 | unsigned int num, | |
679 | struct gnttab_unmap_grant_ref *unmap_ops, | |
680 | struct page **unmap_pages) | |
681 | { | |
682 | unsigned int i, invcount = 0; | |
683 | ||
684 | for (i = 0; i < num; i++) { | |
685 | if (pages[i]->persistent_gnt != NULL) { | |
686 | put_persistent_gnt(blkif, pages[i]->persistent_gnt); | |
687 | continue; | |
688 | } | |
689 | if (pages[i]->handle == BLKBACK_INVALID_HANDLE) | |
690 | continue; | |
691 | unmap_pages[invcount] = pages[i]->page; | |
692 | gnttab_set_unmap_op(&unmap_ops[invcount], vaddr(pages[i]->page), | |
693 | GNTMAP_host_map, pages[i]->handle); | |
694 | pages[i]->handle = BLKBACK_INVALID_HANDLE; | |
695 | invcount++; | |
696 | } | |
697 | ||
698 | return invcount; | |
699 | } | |
700 | ||
701 | static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_queue_data *data) | |
702 | { | |
703 | struct pending_req* pending_req = (struct pending_req*) (data->data); | |
704 | struct xen_blkif *blkif = pending_req->blkif; | |
705 | ||
706 | /* BUG_ON used to reproduce existing behaviour, | |
707 | but is this the best way to deal with this? */ | |
708 | BUG_ON(result); | |
709 | ||
710 | put_free_pages(blkif, data->pages, data->count); | |
711 | make_response(blkif, pending_req->id, | |
712 | pending_req->operation, pending_req->status); | |
713 | free_req(blkif, pending_req); | |
714 | /* | |
715 | * Make sure the request is freed before releasing blkif, | |
716 | * or there could be a race between free_req and the | |
717 | * cleanup done in xen_blkif_free during shutdown. | |
718 | * | |
719 | * NB: The fact that we might try to wake up pending_free_wq | |
720 | * before drain_complete (in case there's a drain going on) | |
721 | * it's not a problem with our current implementation | |
722 | * because we can assure there's no thread waiting on | |
723 | * pending_free_wq if there's a drain going on, but it has | |
724 | * to be taken into account if the current model is changed. | |
725 | */ | |
726 | if (atomic_dec_and_test(&blkif->inflight) && atomic_read(&blkif->drain)) { | |
727 | complete(&blkif->drain_complete); | |
728 | } | |
729 | xen_blkif_put(blkif); | |
730 | } | |
731 | ||
732 | static void xen_blkbk_unmap_and_respond(struct pending_req *req) | |
733 | { | |
734 | struct gntab_unmap_queue_data* work = &req->gnttab_unmap_data; | |
735 | struct xen_blkif *blkif = req->blkif; | |
736 | struct grant_page **pages = req->segments; | |
737 | unsigned int invcount; | |
738 | ||
739 | invcount = xen_blkbk_unmap_prepare(blkif, pages, req->nr_segs, | |
740 | req->unmap, req->unmap_pages); | |
741 | ||
742 | work->data = req; | |
743 | work->done = xen_blkbk_unmap_and_respond_callback; | |
744 | work->unmap_ops = req->unmap; | |
745 | work->kunmap_ops = NULL; | |
746 | work->pages = req->unmap_pages; | |
747 | work->count = invcount; | |
748 | ||
749 | gnttab_unmap_refs_async(&req->gnttab_unmap_data); | |
750 | } | |
751 | ||
752 | ||
753 | /* | |
754 | * Unmap the grant references. | |
755 | * | |
756 | * This could accumulate ops up to the batch size to reduce the number | |
757 | * of hypercalls, but since this is only used in error paths there's | |
758 | * no real need. | |
759 | */ | |
760 | static void xen_blkbk_unmap(struct xen_blkif *blkif, | |
761 | struct grant_page *pages[], | |
762 | int num) | |
763 | { | |
764 | struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
765 | struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
766 | unsigned int invcount = 0; | |
767 | int ret; | |
768 | ||
769 | while (num) { | |
770 | unsigned int batch = min(num, BLKIF_MAX_SEGMENTS_PER_REQUEST); | |
771 | ||
772 | invcount = xen_blkbk_unmap_prepare(blkif, pages, batch, | |
773 | unmap, unmap_pages); | |
774 | if (invcount) { | |
775 | ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount); | |
776 | BUG_ON(ret); | |
777 | put_free_pages(blkif, unmap_pages, invcount); | |
778 | } | |
779 | pages += batch; | |
780 | num -= batch; | |
781 | } | |
782 | } | |
783 | ||
784 | static int xen_blkbk_map(struct xen_blkif *blkif, | |
785 | struct grant_page *pages[], | |
786 | int num, bool ro) | |
787 | { | |
788 | struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
789 | struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST]; | |
790 | struct persistent_gnt *persistent_gnt = NULL; | |
791 | phys_addr_t addr = 0; | |
792 | int i, seg_idx, new_map_idx; | |
793 | int segs_to_map = 0; | |
794 | int ret = 0; | |
795 | int last_map = 0, map_until = 0; | |
796 | int use_persistent_gnts; | |
797 | ||
798 | use_persistent_gnts = (blkif->vbd.feature_gnt_persistent); | |
799 | ||
800 | /* | |
801 | * Fill out preq.nr_sects with proper amount of sectors, and setup | |
802 | * assign map[..] with the PFN of the page in our domain with the | |
803 | * corresponding grant reference for each page. | |
804 | */ | |
805 | again: | |
806 | for (i = map_until; i < num; i++) { | |
807 | uint32_t flags; | |
808 | ||
809 | if (use_persistent_gnts) | |
810 | persistent_gnt = get_persistent_gnt( | |
811 | blkif, | |
812 | pages[i]->gref); | |
813 | ||
814 | if (persistent_gnt) { | |
815 | /* | |
816 | * We are using persistent grants and | |
817 | * the grant is already mapped | |
818 | */ | |
819 | pages[i]->page = persistent_gnt->page; | |
820 | pages[i]->persistent_gnt = persistent_gnt; | |
821 | } else { | |
822 | if (get_free_page(blkif, &pages[i]->page)) | |
823 | goto out_of_memory; | |
824 | addr = vaddr(pages[i]->page); | |
825 | pages_to_gnt[segs_to_map] = pages[i]->page; | |
826 | pages[i]->persistent_gnt = NULL; | |
827 | flags = GNTMAP_host_map; | |
828 | if (!use_persistent_gnts && ro) | |
829 | flags |= GNTMAP_readonly; | |
830 | gnttab_set_map_op(&map[segs_to_map++], addr, | |
831 | flags, pages[i]->gref, | |
832 | blkif->domid); | |
833 | } | |
834 | map_until = i + 1; | |
835 | if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST) | |
836 | break; | |
837 | } | |
838 | ||
839 | if (segs_to_map) { | |
840 | ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map); | |
841 | BUG_ON(ret); | |
842 | } | |
843 | ||
844 | /* | |
845 | * Now swizzle the MFN in our domain with the MFN from the other domain | |
846 | * so that when we access vaddr(pending_req,i) it has the contents of | |
847 | * the page from the other domain. | |
848 | */ | |
849 | for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) { | |
850 | if (!pages[seg_idx]->persistent_gnt) { | |
851 | /* This is a newly mapped grant */ | |
852 | BUG_ON(new_map_idx >= segs_to_map); | |
853 | if (unlikely(map[new_map_idx].status != 0)) { | |
854 | pr_debug("invalid buffer -- could not remap it\n"); | |
855 | put_free_pages(blkif, &pages[seg_idx]->page, 1); | |
856 | pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE; | |
857 | ret |= 1; | |
858 | goto next; | |
859 | } | |
860 | pages[seg_idx]->handle = map[new_map_idx].handle; | |
861 | } else { | |
862 | continue; | |
863 | } | |
864 | if (use_persistent_gnts && | |
865 | blkif->persistent_gnt_c < xen_blkif_max_pgrants) { | |
866 | /* | |
867 | * We are using persistent grants, the grant is | |
868 | * not mapped but we might have room for it. | |
869 | */ | |
870 | persistent_gnt = kmalloc(sizeof(struct persistent_gnt), | |
871 | GFP_KERNEL); | |
872 | if (!persistent_gnt) { | |
873 | /* | |
874 | * If we don't have enough memory to | |
875 | * allocate the persistent_gnt struct | |
876 | * map this grant non-persistenly | |
877 | */ | |
878 | goto next; | |
879 | } | |
880 | persistent_gnt->gnt = map[new_map_idx].ref; | |
881 | persistent_gnt->handle = map[new_map_idx].handle; | |
882 | persistent_gnt->page = pages[seg_idx]->page; | |
883 | if (add_persistent_gnt(blkif, | |
884 | persistent_gnt)) { | |
885 | kfree(persistent_gnt); | |
886 | persistent_gnt = NULL; | |
887 | goto next; | |
888 | } | |
889 | pages[seg_idx]->persistent_gnt = persistent_gnt; | |
890 | pr_debug("grant %u added to the tree of persistent grants, using %u/%u\n", | |
891 | persistent_gnt->gnt, blkif->persistent_gnt_c, | |
892 | xen_blkif_max_pgrants); | |
893 | goto next; | |
894 | } | |
895 | if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) { | |
896 | blkif->vbd.overflow_max_grants = 1; | |
897 | pr_debug("domain %u, device %#x is using maximum number of persistent grants\n", | |
898 | blkif->domid, blkif->vbd.handle); | |
899 | } | |
900 | /* | |
901 | * We could not map this grant persistently, so use it as | |
902 | * a non-persistent grant. | |
903 | */ | |
904 | next: | |
905 | new_map_idx++; | |
906 | } | |
907 | segs_to_map = 0; | |
908 | last_map = map_until; | |
909 | if (map_until != num) | |
910 | goto again; | |
911 | ||
912 | return ret; | |
913 | ||
914 | out_of_memory: | |
915 | pr_alert("%s: out of memory\n", __func__); | |
916 | put_free_pages(blkif, pages_to_gnt, segs_to_map); | |
917 | return -ENOMEM; | |
918 | } | |
919 | ||
920 | static int xen_blkbk_map_seg(struct pending_req *pending_req) | |
921 | { | |
922 | int rc; | |
923 | ||
924 | rc = xen_blkbk_map(pending_req->blkif, pending_req->segments, | |
925 | pending_req->nr_segs, | |
926 | (pending_req->operation != BLKIF_OP_READ)); | |
927 | ||
928 | return rc; | |
929 | } | |
930 | ||
931 | static int xen_blkbk_parse_indirect(struct blkif_request *req, | |
932 | struct pending_req *pending_req, | |
933 | struct seg_buf seg[], | |
934 | struct phys_req *preq) | |
935 | { | |
936 | struct grant_page **pages = pending_req->indirect_pages; | |
937 | struct xen_blkif *blkif = pending_req->blkif; | |
938 | int indirect_grefs, rc, n, nseg, i; | |
939 | struct blkif_request_segment *segments = NULL; | |
940 | ||
941 | nseg = pending_req->nr_segs; | |
942 | indirect_grefs = INDIRECT_PAGES(nseg); | |
943 | BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); | |
944 | ||
945 | for (i = 0; i < indirect_grefs; i++) | |
946 | pages[i]->gref = req->u.indirect.indirect_grefs[i]; | |
947 | ||
948 | rc = xen_blkbk_map(blkif, pages, indirect_grefs, true); | |
949 | if (rc) | |
950 | goto unmap; | |
951 | ||
952 | for (n = 0, i = 0; n < nseg; n++) { | |
953 | if ((n % SEGS_PER_INDIRECT_FRAME) == 0) { | |
954 | /* Map indirect segments */ | |
955 | if (segments) | |
956 | kunmap_atomic(segments); | |
957 | segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page); | |
958 | } | |
959 | i = n % SEGS_PER_INDIRECT_FRAME; | |
960 | pending_req->segments[n]->gref = segments[i].gref; | |
961 | seg[n].nsec = segments[i].last_sect - | |
962 | segments[i].first_sect + 1; | |
963 | seg[n].offset = (segments[i].first_sect << 9); | |
964 | if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) || | |
965 | (segments[i].last_sect < segments[i].first_sect)) { | |
966 | rc = -EINVAL; | |
967 | goto unmap; | |
968 | } | |
969 | preq->nr_sects += seg[n].nsec; | |
970 | } | |
971 | ||
972 | unmap: | |
973 | if (segments) | |
974 | kunmap_atomic(segments); | |
975 | xen_blkbk_unmap(blkif, pages, indirect_grefs); | |
976 | return rc; | |
977 | } | |
978 | ||
979 | static int dispatch_discard_io(struct xen_blkif *blkif, | |
980 | struct blkif_request *req) | |
981 | { | |
982 | int err = 0; | |
983 | int status = BLKIF_RSP_OKAY; | |
984 | struct block_device *bdev = blkif->vbd.bdev; | |
985 | unsigned long secure; | |
986 | struct phys_req preq; | |
987 | ||
988 | xen_blkif_get(blkif); | |
989 | ||
990 | preq.sector_number = req->u.discard.sector_number; | |
991 | preq.nr_sects = req->u.discard.nr_sectors; | |
992 | ||
993 | err = xen_vbd_translate(&preq, blkif, WRITE); | |
994 | if (err) { | |
995 | pr_warn("access denied: DISCARD [%llu->%llu] on dev=%04x\n", | |
996 | preq.sector_number, | |
997 | preq.sector_number + preq.nr_sects, blkif->vbd.pdevice); | |
998 | goto fail_response; | |
999 | } | |
1000 | blkif->st_ds_req++; | |
1001 | ||
1002 | secure = (blkif->vbd.discard_secure && | |
1003 | (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? | |
1004 | BLKDEV_DISCARD_SECURE : 0; | |
1005 | ||
1006 | err = blkdev_issue_discard(bdev, req->u.discard.sector_number, | |
1007 | req->u.discard.nr_sectors, | |
1008 | GFP_KERNEL, secure); | |
1009 | fail_response: | |
1010 | if (err == -EOPNOTSUPP) { | |
1011 | pr_debug("discard op failed, not supported\n"); | |
1012 | status = BLKIF_RSP_EOPNOTSUPP; | |
1013 | } else if (err) | |
1014 | status = BLKIF_RSP_ERROR; | |
1015 | ||
1016 | make_response(blkif, req->u.discard.id, req->operation, status); | |
1017 | xen_blkif_put(blkif); | |
1018 | return err; | |
1019 | } | |
1020 | ||
1021 | static int dispatch_other_io(struct xen_blkif *blkif, | |
1022 | struct blkif_request *req, | |
1023 | struct pending_req *pending_req) | |
1024 | { | |
1025 | free_req(blkif, pending_req); | |
1026 | make_response(blkif, req->u.other.id, req->operation, | |
1027 | BLKIF_RSP_EOPNOTSUPP); | |
1028 | return -EIO; | |
1029 | } | |
1030 | ||
1031 | static void xen_blk_drain_io(struct xen_blkif *blkif) | |
1032 | { | |
1033 | atomic_set(&blkif->drain, 1); | |
1034 | do { | |
1035 | if (atomic_read(&blkif->inflight) == 0) | |
1036 | break; | |
1037 | wait_for_completion_interruptible_timeout( | |
1038 | &blkif->drain_complete, HZ); | |
1039 | ||
1040 | if (!atomic_read(&blkif->drain)) | |
1041 | break; | |
1042 | } while (!kthread_should_stop()); | |
1043 | atomic_set(&blkif->drain, 0); | |
1044 | } | |
1045 | ||
1046 | /* | |
1047 | * Completion callback on the bio's. Called as bh->b_end_io() | |
1048 | */ | |
1049 | ||
1050 | static void __end_block_io_op(struct pending_req *pending_req, int error) | |
1051 | { | |
1052 | /* An error fails the entire request. */ | |
1053 | if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && | |
1054 | (error == -EOPNOTSUPP)) { | |
1055 | pr_debug("flush diskcache op failed, not supported\n"); | |
1056 | xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); | |
1057 | pending_req->status = BLKIF_RSP_EOPNOTSUPP; | |
1058 | } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && | |
1059 | (error == -EOPNOTSUPP)) { | |
1060 | pr_debug("write barrier op failed, not supported\n"); | |
1061 | xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0); | |
1062 | pending_req->status = BLKIF_RSP_EOPNOTSUPP; | |
1063 | } else if (error) { | |
1064 | pr_debug("Buffer not up-to-date at end of operation," | |
1065 | " error=%d\n", error); | |
1066 | pending_req->status = BLKIF_RSP_ERROR; | |
1067 | } | |
1068 | ||
1069 | /* | |
1070 | * If all of the bio's have completed it is time to unmap | |
1071 | * the grant references associated with 'request' and provide | |
1072 | * the proper response on the ring. | |
1073 | */ | |
1074 | if (atomic_dec_and_test(&pending_req->pendcnt)) | |
1075 | xen_blkbk_unmap_and_respond(pending_req); | |
1076 | } | |
1077 | ||
1078 | /* | |
1079 | * bio callback. | |
1080 | */ | |
1081 | static void end_block_io_op(struct bio *bio) | |
1082 | { | |
1083 | __end_block_io_op(bio->bi_private, bio->bi_error); | |
1084 | bio_put(bio); | |
1085 | } | |
1086 | ||
1087 | ||
1088 | ||
1089 | /* | |
1090 | * Function to copy the from the ring buffer the 'struct blkif_request' | |
1091 | * (which has the sectors we want, number of them, grant references, etc), | |
1092 | * and transmute it to the block API to hand it over to the proper block disk. | |
1093 | */ | |
1094 | static int | |
1095 | __do_block_io_op(struct xen_blkif *blkif) | |
1096 | { | |
1097 | union blkif_back_rings *blk_rings = &blkif->blk_rings; | |
1098 | struct blkif_request req; | |
1099 | struct pending_req *pending_req; | |
1100 | RING_IDX rc, rp; | |
1101 | int more_to_do = 0; | |
1102 | ||
1103 | rc = blk_rings->common.req_cons; | |
1104 | rp = blk_rings->common.sring->req_prod; | |
1105 | rmb(); /* Ensure we see queued requests up to 'rp'. */ | |
1106 | ||
1107 | if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) { | |
1108 | rc = blk_rings->common.rsp_prod_pvt; | |
1109 | pr_warn("Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n", | |
1110 | rp, rc, rp - rc, blkif->vbd.pdevice); | |
1111 | return -EACCES; | |
1112 | } | |
1113 | while (rc != rp) { | |
1114 | ||
1115 | if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) | |
1116 | break; | |
1117 | ||
1118 | if (kthread_should_stop()) { | |
1119 | more_to_do = 1; | |
1120 | break; | |
1121 | } | |
1122 | ||
1123 | pending_req = alloc_req(blkif); | |
1124 | if (NULL == pending_req) { | |
1125 | blkif->st_oo_req++; | |
1126 | more_to_do = 1; | |
1127 | break; | |
1128 | } | |
1129 | ||
1130 | switch (blkif->blk_protocol) { | |
1131 | case BLKIF_PROTOCOL_NATIVE: | |
1132 | memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); | |
1133 | break; | |
1134 | case BLKIF_PROTOCOL_X86_32: | |
1135 | blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); | |
1136 | break; | |
1137 | case BLKIF_PROTOCOL_X86_64: | |
1138 | blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); | |
1139 | break; | |
1140 | default: | |
1141 | BUG(); | |
1142 | } | |
1143 | blk_rings->common.req_cons = ++rc; /* before make_response() */ | |
1144 | ||
1145 | /* Apply all sanity checks to /private copy/ of request. */ | |
1146 | barrier(); | |
1147 | ||
1148 | switch (req.operation) { | |
1149 | case BLKIF_OP_READ: | |
1150 | case BLKIF_OP_WRITE: | |
1151 | case BLKIF_OP_WRITE_BARRIER: | |
1152 | case BLKIF_OP_FLUSH_DISKCACHE: | |
1153 | case BLKIF_OP_INDIRECT: | |
1154 | if (dispatch_rw_block_io(blkif, &req, pending_req)) | |
1155 | goto done; | |
1156 | break; | |
1157 | case BLKIF_OP_DISCARD: | |
1158 | free_req(blkif, pending_req); | |
1159 | if (dispatch_discard_io(blkif, &req)) | |
1160 | goto done; | |
1161 | break; | |
1162 | default: | |
1163 | if (dispatch_other_io(blkif, &req, pending_req)) | |
1164 | goto done; | |
1165 | break; | |
1166 | } | |
1167 | ||
1168 | /* Yield point for this unbounded loop. */ | |
1169 | cond_resched(); | |
1170 | } | |
1171 | done: | |
1172 | return more_to_do; | |
1173 | } | |
1174 | ||
1175 | static int | |
1176 | do_block_io_op(struct xen_blkif *blkif) | |
1177 | { | |
1178 | union blkif_back_rings *blk_rings = &blkif->blk_rings; | |
1179 | int more_to_do; | |
1180 | ||
1181 | do { | |
1182 | more_to_do = __do_block_io_op(blkif); | |
1183 | if (more_to_do) | |
1184 | break; | |
1185 | ||
1186 | RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); | |
1187 | } while (more_to_do); | |
1188 | ||
1189 | return more_to_do; | |
1190 | } | |
1191 | /* | |
1192 | * Transmutation of the 'struct blkif_request' to a proper 'struct bio' | |
1193 | * and call the 'submit_bio' to pass it to the underlying storage. | |
1194 | */ | |
1195 | static int dispatch_rw_block_io(struct xen_blkif *blkif, | |
1196 | struct blkif_request *req, | |
1197 | struct pending_req *pending_req) | |
1198 | { | |
1199 | struct phys_req preq; | |
1200 | struct seg_buf *seg = pending_req->seg; | |
1201 | unsigned int nseg; | |
1202 | struct bio *bio = NULL; | |
1203 | struct bio **biolist = pending_req->biolist; | |
1204 | int i, nbio = 0; | |
1205 | int operation; | |
1206 | struct blk_plug plug; | |
1207 | bool drain = false; | |
1208 | struct grant_page **pages = pending_req->segments; | |
1209 | unsigned short req_operation; | |
1210 | ||
1211 | req_operation = req->operation == BLKIF_OP_INDIRECT ? | |
1212 | req->u.indirect.indirect_op : req->operation; | |
1213 | if ((req->operation == BLKIF_OP_INDIRECT) && | |
1214 | (req_operation != BLKIF_OP_READ) && | |
1215 | (req_operation != BLKIF_OP_WRITE)) { | |
1216 | pr_debug("Invalid indirect operation (%u)\n", req_operation); | |
1217 | goto fail_response; | |
1218 | } | |
1219 | ||
1220 | switch (req_operation) { | |
1221 | case BLKIF_OP_READ: | |
1222 | blkif->st_rd_req++; | |
1223 | operation = READ; | |
1224 | break; | |
1225 | case BLKIF_OP_WRITE: | |
1226 | blkif->st_wr_req++; | |
1227 | operation = WRITE_ODIRECT; | |
1228 | break; | |
1229 | case BLKIF_OP_WRITE_BARRIER: | |
1230 | drain = true; | |
1231 | case BLKIF_OP_FLUSH_DISKCACHE: | |
1232 | blkif->st_f_req++; | |
1233 | operation = WRITE_FLUSH; | |
1234 | break; | |
1235 | default: | |
1236 | operation = 0; /* make gcc happy */ | |
1237 | goto fail_response; | |
1238 | break; | |
1239 | } | |
1240 | ||
1241 | /* Check that the number of segments is sane. */ | |
1242 | nseg = req->operation == BLKIF_OP_INDIRECT ? | |
1243 | req->u.indirect.nr_segments : req->u.rw.nr_segments; | |
1244 | ||
1245 | if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || | |
1246 | unlikely((req->operation != BLKIF_OP_INDIRECT) && | |
1247 | (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) || | |
1248 | unlikely((req->operation == BLKIF_OP_INDIRECT) && | |
1249 | (nseg > MAX_INDIRECT_SEGMENTS))) { | |
1250 | pr_debug("Bad number of segments in request (%d)\n", nseg); | |
1251 | /* Haven't submitted any bio's yet. */ | |
1252 | goto fail_response; | |
1253 | } | |
1254 | ||
1255 | preq.nr_sects = 0; | |
1256 | ||
1257 | pending_req->blkif = blkif; | |
1258 | pending_req->id = req->u.rw.id; | |
1259 | pending_req->operation = req_operation; | |
1260 | pending_req->status = BLKIF_RSP_OKAY; | |
1261 | pending_req->nr_segs = nseg; | |
1262 | ||
1263 | if (req->operation != BLKIF_OP_INDIRECT) { | |
1264 | preq.dev = req->u.rw.handle; | |
1265 | preq.sector_number = req->u.rw.sector_number; | |
1266 | for (i = 0; i < nseg; i++) { | |
1267 | pages[i]->gref = req->u.rw.seg[i].gref; | |
1268 | seg[i].nsec = req->u.rw.seg[i].last_sect - | |
1269 | req->u.rw.seg[i].first_sect + 1; | |
1270 | seg[i].offset = (req->u.rw.seg[i].first_sect << 9); | |
1271 | if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || | |
1272 | (req->u.rw.seg[i].last_sect < | |
1273 | req->u.rw.seg[i].first_sect)) | |
1274 | goto fail_response; | |
1275 | preq.nr_sects += seg[i].nsec; | |
1276 | } | |
1277 | } else { | |
1278 | preq.dev = req->u.indirect.handle; | |
1279 | preq.sector_number = req->u.indirect.sector_number; | |
1280 | if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq)) | |
1281 | goto fail_response; | |
1282 | } | |
1283 | ||
1284 | if (xen_vbd_translate(&preq, blkif, operation) != 0) { | |
1285 | pr_debug("access denied: %s of [%llu,%llu] on dev=%04x\n", | |
1286 | operation == READ ? "read" : "write", | |
1287 | preq.sector_number, | |
1288 | preq.sector_number + preq.nr_sects, | |
1289 | blkif->vbd.pdevice); | |
1290 | goto fail_response; | |
1291 | } | |
1292 | ||
1293 | /* | |
1294 | * This check _MUST_ be done after xen_vbd_translate as the preq.bdev | |
1295 | * is set there. | |
1296 | */ | |
1297 | for (i = 0; i < nseg; i++) { | |
1298 | if (((int)preq.sector_number|(int)seg[i].nsec) & | |
1299 | ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { | |
1300 | pr_debug("Misaligned I/O request from domain %d\n", | |
1301 | blkif->domid); | |
1302 | goto fail_response; | |
1303 | } | |
1304 | } | |
1305 | ||
1306 | /* Wait on all outstanding I/O's and once that has been completed | |
1307 | * issue the WRITE_FLUSH. | |
1308 | */ | |
1309 | if (drain) | |
1310 | xen_blk_drain_io(pending_req->blkif); | |
1311 | ||
1312 | /* | |
1313 | * If we have failed at this point, we need to undo the M2P override, | |
1314 | * set gnttab_set_unmap_op on all of the grant references and perform | |
1315 | * the hypercall to unmap the grants - that is all done in | |
1316 | * xen_blkbk_unmap. | |
1317 | */ | |
1318 | if (xen_blkbk_map_seg(pending_req)) | |
1319 | goto fail_flush; | |
1320 | ||
1321 | /* | |
1322 | * This corresponding xen_blkif_put is done in __end_block_io_op, or | |
1323 | * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. | |
1324 | */ | |
1325 | xen_blkif_get(blkif); | |
1326 | atomic_inc(&blkif->inflight); | |
1327 | ||
1328 | for (i = 0; i < nseg; i++) { | |
1329 | while ((bio == NULL) || | |
1330 | (bio_add_page(bio, | |
1331 | pages[i]->page, | |
1332 | seg[i].nsec << 9, | |
1333 | seg[i].offset) == 0)) { | |
1334 | ||
1335 | int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES); | |
1336 | bio = bio_alloc(GFP_KERNEL, nr_iovecs); | |
1337 | if (unlikely(bio == NULL)) | |
1338 | goto fail_put_bio; | |
1339 | ||
1340 | biolist[nbio++] = bio; | |
1341 | bio->bi_bdev = preq.bdev; | |
1342 | bio->bi_private = pending_req; | |
1343 | bio->bi_end_io = end_block_io_op; | |
1344 | bio->bi_iter.bi_sector = preq.sector_number; | |
1345 | } | |
1346 | ||
1347 | preq.sector_number += seg[i].nsec; | |
1348 | } | |
1349 | ||
1350 | /* This will be hit if the operation was a flush or discard. */ | |
1351 | if (!bio) { | |
1352 | BUG_ON(operation != WRITE_FLUSH); | |
1353 | ||
1354 | bio = bio_alloc(GFP_KERNEL, 0); | |
1355 | if (unlikely(bio == NULL)) | |
1356 | goto fail_put_bio; | |
1357 | ||
1358 | biolist[nbio++] = bio; | |
1359 | bio->bi_bdev = preq.bdev; | |
1360 | bio->bi_private = pending_req; | |
1361 | bio->bi_end_io = end_block_io_op; | |
1362 | } | |
1363 | ||
1364 | atomic_set(&pending_req->pendcnt, nbio); | |
1365 | blk_start_plug(&plug); | |
1366 | ||
1367 | for (i = 0; i < nbio; i++) | |
1368 | submit_bio(operation, biolist[i]); | |
1369 | ||
1370 | /* Let the I/Os go.. */ | |
1371 | blk_finish_plug(&plug); | |
1372 | ||
1373 | if (operation == READ) | |
1374 | blkif->st_rd_sect += preq.nr_sects; | |
1375 | else if (operation & WRITE) | |
1376 | blkif->st_wr_sect += preq.nr_sects; | |
1377 | ||
1378 | return 0; | |
1379 | ||
1380 | fail_flush: | |
1381 | xen_blkbk_unmap(blkif, pending_req->segments, | |
1382 | pending_req->nr_segs); | |
1383 | fail_response: | |
1384 | /* Haven't submitted any bio's yet. */ | |
1385 | make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR); | |
1386 | free_req(blkif, pending_req); | |
1387 | msleep(1); /* back off a bit */ | |
1388 | return -EIO; | |
1389 | ||
1390 | fail_put_bio: | |
1391 | for (i = 0; i < nbio; i++) | |
1392 | bio_put(biolist[i]); | |
1393 | atomic_set(&pending_req->pendcnt, 1); | |
1394 | __end_block_io_op(pending_req, -EINVAL); | |
1395 | msleep(1); /* back off a bit */ | |
1396 | return -EIO; | |
1397 | } | |
1398 | ||
1399 | ||
1400 | ||
1401 | /* | |
1402 | * Put a response on the ring on how the operation fared. | |
1403 | */ | |
1404 | static void make_response(struct xen_blkif *blkif, u64 id, | |
1405 | unsigned short op, int st) | |
1406 | { | |
1407 | struct blkif_response resp; | |
1408 | unsigned long flags; | |
1409 | union blkif_back_rings *blk_rings = &blkif->blk_rings; | |
1410 | int notify; | |
1411 | ||
1412 | resp.id = id; | |
1413 | resp.operation = op; | |
1414 | resp.status = st; | |
1415 | ||
1416 | spin_lock_irqsave(&blkif->blk_ring_lock, flags); | |
1417 | /* Place on the response ring for the relevant domain. */ | |
1418 | switch (blkif->blk_protocol) { | |
1419 | case BLKIF_PROTOCOL_NATIVE: | |
1420 | memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), | |
1421 | &resp, sizeof(resp)); | |
1422 | break; | |
1423 | case BLKIF_PROTOCOL_X86_32: | |
1424 | memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), | |
1425 | &resp, sizeof(resp)); | |
1426 | break; | |
1427 | case BLKIF_PROTOCOL_X86_64: | |
1428 | memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), | |
1429 | &resp, sizeof(resp)); | |
1430 | break; | |
1431 | default: | |
1432 | BUG(); | |
1433 | } | |
1434 | blk_rings->common.rsp_prod_pvt++; | |
1435 | RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); | |
1436 | spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); | |
1437 | if (notify) | |
1438 | notify_remote_via_irq(blkif->irq); | |
1439 | } | |
1440 | ||
1441 | static int __init xen_blkif_init(void) | |
1442 | { | |
1443 | int rc = 0; | |
1444 | ||
1445 | if (!xen_domain()) | |
1446 | return -ENODEV; | |
1447 | ||
1448 | if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER) { | |
1449 | pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", | |
1450 | xen_blkif_max_ring_order, XENBUS_MAX_RING_PAGE_ORDER); | |
1451 | xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER; | |
1452 | } | |
1453 | ||
1454 | rc = xen_blkif_interface_init(); | |
1455 | if (rc) | |
1456 | goto failed_init; | |
1457 | ||
1458 | rc = xen_blkif_xenbus_init(); | |
1459 | if (rc) | |
1460 | goto failed_init; | |
1461 | ||
1462 | failed_init: | |
1463 | return rc; | |
1464 | } | |
1465 | ||
1466 | module_init(xen_blkif_init); | |
1467 | ||
1468 | MODULE_LICENSE("Dual BSD/GPL"); | |
1469 | MODULE_ALIAS("xen-backend:vbd"); |