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 * The LRU mechanism to clean the lists of persistent grants needs to 88 * be executed periodically. The time interval between consecutive executions 89 * of the purge mechanism is set in ms. 90 */ 91 #define LRU_INTERVAL 100 92 93 /* 94 * When the persistent grants list is full we will remove unused grants 95 * from the list. The percent number of grants to be removed at each LRU 96 * execution. 97 */ 98 #define LRU_PERCENT_CLEAN 5 99 100 /* Run-time switchable: /sys/module/blkback/parameters/ */ 101 static unsigned int log_stats; 102 module_param(log_stats, int, 0644); 103 104 #define BLKBACK_INVALID_HANDLE (~0) 105 106 /* Number of free pages to remove on each call to gnttab_free_pages */ 107 #define NUM_BATCH_FREE_PAGES 10 108 109 static inline int get_free_page(struct xen_blkif *blkif, struct page **page) 110 { 111 unsigned long flags; 112 113 spin_lock_irqsave(&blkif->free_pages_lock, flags); 114 if (list_empty(&blkif->free_pages)) { 115 BUG_ON(blkif->free_pages_num != 0); 116 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 117 return gnttab_alloc_pages(1, page); 118 } 119 BUG_ON(blkif->free_pages_num == 0); 120 page[0] = list_first_entry(&blkif->free_pages, struct page, lru); 121 list_del(&page[0]->lru); 122 blkif->free_pages_num--; 123 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 124 125 return 0; 126 } 127 128 static inline void put_free_pages(struct xen_blkif *blkif, struct page **page, 129 int num) 130 { 131 unsigned long flags; 132 int i; 133 134 spin_lock_irqsave(&blkif->free_pages_lock, flags); 135 for (i = 0; i < num; i++) 136 list_add(&page[i]->lru, &blkif->free_pages); 137 blkif->free_pages_num += num; 138 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 139 } 140 141 static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num) 142 { 143 /* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */ 144 struct page *page[NUM_BATCH_FREE_PAGES]; 145 unsigned int num_pages = 0; 146 unsigned long flags; 147 148 spin_lock_irqsave(&blkif->free_pages_lock, flags); 149 while (blkif->free_pages_num > num) { 150 BUG_ON(list_empty(&blkif->free_pages)); 151 page[num_pages] = list_first_entry(&blkif->free_pages, 152 struct page, lru); 153 list_del(&page[num_pages]->lru); 154 blkif->free_pages_num--; 155 if (++num_pages == NUM_BATCH_FREE_PAGES) { 156 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 157 gnttab_free_pages(num_pages, page); 158 spin_lock_irqsave(&blkif->free_pages_lock, flags); 159 num_pages = 0; 160 } 161 } 162 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 163 if (num_pages != 0) 164 gnttab_free_pages(num_pages, page); 165 } 166 167 #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page))) 168 169 static int do_block_io_op(struct xen_blkif *blkif); 170 static int dispatch_rw_block_io(struct xen_blkif *blkif, 171 struct blkif_request *req, 172 struct pending_req *pending_req); 173 static void make_response(struct xen_blkif *blkif, u64 id, 174 unsigned short op, int st); 175 176 #define foreach_grant_safe(pos, n, rbtree, node) \ 177 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \ 178 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \ 179 &(pos)->node != NULL; \ 180 (pos) = container_of(n, typeof(*(pos)), node), \ 181 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL) 182 183 184 /* 185 * We don't need locking around the persistent grant helpers 186 * because blkback uses a single-thread for each backed, so we 187 * can be sure that this functions will never be called recursively. 188 * 189 * The only exception to that is put_persistent_grant, that can be called 190 * from interrupt context (by xen_blkbk_unmap), so we have to use atomic 191 * bit operations to modify the flags of a persistent grant and to count 192 * the number of used grants. 193 */ 194 static int add_persistent_gnt(struct xen_blkif *blkif, 195 struct persistent_gnt *persistent_gnt) 196 { 197 struct rb_node **new = NULL, *parent = NULL; 198 struct persistent_gnt *this; 199 200 if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) { 201 if (!blkif->vbd.overflow_max_grants) 202 blkif->vbd.overflow_max_grants = 1; 203 return -EBUSY; 204 } 205 /* Figure out where to put new node */ 206 new = &blkif->persistent_gnts.rb_node; 207 while (*new) { 208 this = container_of(*new, struct persistent_gnt, node); 209 210 parent = *new; 211 if (persistent_gnt->gnt < this->gnt) 212 new = &((*new)->rb_left); 213 else if (persistent_gnt->gnt > this->gnt) 214 new = &((*new)->rb_right); 215 else { 216 pr_alert_ratelimited("trying to add a gref that's already in the tree\n"); 217 return -EINVAL; 218 } 219 } 220 221 bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE); 222 set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); 223 /* Add new node and rebalance tree. */ 224 rb_link_node(&(persistent_gnt->node), parent, new); 225 rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts); 226 blkif->persistent_gnt_c++; 227 atomic_inc(&blkif->persistent_gnt_in_use); 228 return 0; 229 } 230 231 static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif, 232 grant_ref_t gref) 233 { 234 struct persistent_gnt *data; 235 struct rb_node *node = NULL; 236 237 node = blkif->persistent_gnts.rb_node; 238 while (node) { 239 data = container_of(node, struct persistent_gnt, node); 240 241 if (gref < data->gnt) 242 node = node->rb_left; 243 else if (gref > data->gnt) 244 node = node->rb_right; 245 else { 246 if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) { 247 pr_alert_ratelimited("requesting a grant already in use\n"); 248 return NULL; 249 } 250 set_bit(PERSISTENT_GNT_ACTIVE, data->flags); 251 atomic_inc(&blkif->persistent_gnt_in_use); 252 return data; 253 } 254 } 255 return NULL; 256 } 257 258 static void put_persistent_gnt(struct xen_blkif *blkif, 259 struct persistent_gnt *persistent_gnt) 260 { 261 if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) 262 pr_alert_ratelimited("freeing a grant already unused\n"); 263 set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); 264 clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); 265 atomic_dec(&blkif->persistent_gnt_in_use); 266 } 267 268 static void free_persistent_gnts_unmap_callback(int result, 269 struct gntab_unmap_queue_data *data) 270 { 271 struct completion *c = data->data; 272 273 /* BUG_ON used to reproduce existing behaviour, 274 but is this the best way to deal with this? */ 275 BUG_ON(result); 276 complete(c); 277 } 278 279 static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root, 280 unsigned int num) 281 { 282 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 283 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 284 struct persistent_gnt *persistent_gnt; 285 struct rb_node *n; 286 int segs_to_unmap = 0; 287 struct gntab_unmap_queue_data unmap_data; 288 struct completion unmap_completion; 289 290 init_completion(&unmap_completion); 291 292 unmap_data.data = &unmap_completion; 293 unmap_data.done = &free_persistent_gnts_unmap_callback; 294 unmap_data.pages = pages; 295 unmap_data.unmap_ops = unmap; 296 unmap_data.kunmap_ops = NULL; 297 298 foreach_grant_safe(persistent_gnt, n, root, node) { 299 BUG_ON(persistent_gnt->handle == 300 BLKBACK_INVALID_HANDLE); 301 gnttab_set_unmap_op(&unmap[segs_to_unmap], 302 (unsigned long) pfn_to_kaddr(page_to_pfn( 303 persistent_gnt->page)), 304 GNTMAP_host_map, 305 persistent_gnt->handle); 306 307 pages[segs_to_unmap] = persistent_gnt->page; 308 309 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST || 310 !rb_next(&persistent_gnt->node)) { 311 312 unmap_data.count = segs_to_unmap; 313 gnttab_unmap_refs_async(&unmap_data); 314 wait_for_completion(&unmap_completion); 315 316 put_free_pages(blkif, pages, segs_to_unmap); 317 segs_to_unmap = 0; 318 } 319 320 rb_erase(&persistent_gnt->node, root); 321 kfree(persistent_gnt); 322 num--; 323 } 324 BUG_ON(num != 0); 325 } 326 327 void xen_blkbk_unmap_purged_grants(struct work_struct *work) 328 { 329 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 330 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 331 struct persistent_gnt *persistent_gnt; 332 int ret, segs_to_unmap = 0; 333 struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work); 334 335 while(!list_empty(&blkif->persistent_purge_list)) { 336 persistent_gnt = list_first_entry(&blkif->persistent_purge_list, 337 struct persistent_gnt, 338 remove_node); 339 list_del(&persistent_gnt->remove_node); 340 341 gnttab_set_unmap_op(&unmap[segs_to_unmap], 342 vaddr(persistent_gnt->page), 343 GNTMAP_host_map, 344 persistent_gnt->handle); 345 346 pages[segs_to_unmap] = persistent_gnt->page; 347 348 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) { 349 ret = gnttab_unmap_refs(unmap, NULL, pages, 350 segs_to_unmap); 351 BUG_ON(ret); 352 put_free_pages(blkif, pages, segs_to_unmap); 353 segs_to_unmap = 0; 354 } 355 kfree(persistent_gnt); 356 } 357 if (segs_to_unmap > 0) { 358 ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap); 359 BUG_ON(ret); 360 put_free_pages(blkif, pages, segs_to_unmap); 361 } 362 } 363 364 static void purge_persistent_gnt(struct xen_blkif *blkif) 365 { 366 struct persistent_gnt *persistent_gnt; 367 struct rb_node *n; 368 unsigned int num_clean, total; 369 bool scan_used = false, clean_used = false; 370 struct rb_root *root; 371 372 if (blkif->persistent_gnt_c < xen_blkif_max_pgrants || 373 (blkif->persistent_gnt_c == xen_blkif_max_pgrants && 374 !blkif->vbd.overflow_max_grants)) { 375 return; 376 } 377 378 if (work_pending(&blkif->persistent_purge_work)) { 379 pr_alert_ratelimited("Scheduled work from previous purge is still pending, cannot purge list\n"); 380 return; 381 } 382 383 num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN; 384 num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean; 385 num_clean = min(blkif->persistent_gnt_c, num_clean); 386 if ((num_clean == 0) || 387 (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use)))) 388 return; 389 390 /* 391 * At this point, we can assure that there will be no calls 392 * to get_persistent_grant (because we are executing this code from 393 * xen_blkif_schedule), there can only be calls to put_persistent_gnt, 394 * which means that the number of currently used grants will go down, 395 * but never up, so we will always be able to remove the requested 396 * number of grants. 397 */ 398 399 total = num_clean; 400 401 pr_debug("Going to purge %u persistent grants\n", num_clean); 402 403 BUG_ON(!list_empty(&blkif->persistent_purge_list)); 404 root = &blkif->persistent_gnts; 405 purge_list: 406 foreach_grant_safe(persistent_gnt, n, root, node) { 407 BUG_ON(persistent_gnt->handle == 408 BLKBACK_INVALID_HANDLE); 409 410 if (clean_used) { 411 clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); 412 continue; 413 } 414 415 if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) 416 continue; 417 if (!scan_used && 418 (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags))) 419 continue; 420 421 rb_erase(&persistent_gnt->node, root); 422 list_add(&persistent_gnt->remove_node, 423 &blkif->persistent_purge_list); 424 if (--num_clean == 0) 425 goto finished; 426 } 427 /* 428 * If we get here it means we also need to start cleaning 429 * grants that were used since last purge in order to cope 430 * with the requested num 431 */ 432 if (!scan_used && !clean_used) { 433 pr_debug("Still missing %u purged frames\n", num_clean); 434 scan_used = true; 435 goto purge_list; 436 } 437 finished: 438 if (!clean_used) { 439 pr_debug("Finished scanning for grants to clean, removing used flag\n"); 440 clean_used = true; 441 goto purge_list; 442 } 443 444 blkif->persistent_gnt_c -= (total - num_clean); 445 blkif->vbd.overflow_max_grants = 0; 446 447 /* We can defer this work */ 448 schedule_work(&blkif->persistent_purge_work); 449 pr_debug("Purged %u/%u\n", (total - num_clean), total); 450 return; 451 } 452 453 /* 454 * Retrieve from the 'pending_reqs' a free pending_req structure to be used. 455 */ 456 static struct pending_req *alloc_req(struct xen_blkif *blkif) 457 { 458 struct pending_req *req = NULL; 459 unsigned long flags; 460 461 spin_lock_irqsave(&blkif->pending_free_lock, flags); 462 if (!list_empty(&blkif->pending_free)) { 463 req = list_entry(blkif->pending_free.next, struct pending_req, 464 free_list); 465 list_del(&req->free_list); 466 } 467 spin_unlock_irqrestore(&blkif->pending_free_lock, flags); 468 return req; 469 } 470 471 /* 472 * Return the 'pending_req' structure back to the freepool. We also 473 * wake up the thread if it was waiting for a free page. 474 */ 475 static void free_req(struct xen_blkif *blkif, struct pending_req *req) 476 { 477 unsigned long flags; 478 int was_empty; 479 480 spin_lock_irqsave(&blkif->pending_free_lock, flags); 481 was_empty = list_empty(&blkif->pending_free); 482 list_add(&req->free_list, &blkif->pending_free); 483 spin_unlock_irqrestore(&blkif->pending_free_lock, flags); 484 if (was_empty) 485 wake_up(&blkif->pending_free_wq); 486 } 487 488 /* 489 * Routines for managing virtual block devices (vbds). 490 */ 491 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, 492 int operation) 493 { 494 struct xen_vbd *vbd = &blkif->vbd; 495 int rc = -EACCES; 496 497 if ((operation != READ) && vbd->readonly) 498 goto out; 499 500 if (likely(req->nr_sects)) { 501 blkif_sector_t end = req->sector_number + req->nr_sects; 502 503 if (unlikely(end < req->sector_number)) 504 goto out; 505 if (unlikely(end > vbd_sz(vbd))) 506 goto out; 507 } 508 509 req->dev = vbd->pdevice; 510 req->bdev = vbd->bdev; 511 rc = 0; 512 513 out: 514 return rc; 515 } 516 517 static void xen_vbd_resize(struct xen_blkif *blkif) 518 { 519 struct xen_vbd *vbd = &blkif->vbd; 520 struct xenbus_transaction xbt; 521 int err; 522 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); 523 unsigned long long new_size = vbd_sz(vbd); 524 525 pr_info("VBD Resize: Domid: %d, Device: (%d, %d)\n", 526 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); 527 pr_info("VBD Resize: new size %llu\n", new_size); 528 vbd->size = new_size; 529 again: 530 err = xenbus_transaction_start(&xbt); 531 if (err) { 532 pr_warn("Error starting transaction\n"); 533 return; 534 } 535 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 536 (unsigned long long)vbd_sz(vbd)); 537 if (err) { 538 pr_warn("Error writing new size\n"); 539 goto abort; 540 } 541 /* 542 * Write the current state; we will use this to synchronize 543 * the front-end. If the current state is "connected" the 544 * front-end will get the new size information online. 545 */ 546 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); 547 if (err) { 548 pr_warn("Error writing the state\n"); 549 goto abort; 550 } 551 552 err = xenbus_transaction_end(xbt, 0); 553 if (err == -EAGAIN) 554 goto again; 555 if (err) 556 pr_warn("Error ending transaction\n"); 557 return; 558 abort: 559 xenbus_transaction_end(xbt, 1); 560 } 561 562 /* 563 * Notification from the guest OS. 564 */ 565 static void blkif_notify_work(struct xen_blkif *blkif) 566 { 567 blkif->waiting_reqs = 1; 568 wake_up(&blkif->wq); 569 } 570 571 irqreturn_t xen_blkif_be_int(int irq, void *dev_id) 572 { 573 blkif_notify_work(dev_id); 574 return IRQ_HANDLED; 575 } 576 577 /* 578 * SCHEDULER FUNCTIONS 579 */ 580 581 static void print_stats(struct xen_blkif *blkif) 582 { 583 pr_info("(%s): oo %3llu | rd %4llu | wr %4llu | f %4llu" 584 " | ds %4llu | pg: %4u/%4d\n", 585 current->comm, blkif->st_oo_req, 586 blkif->st_rd_req, blkif->st_wr_req, 587 blkif->st_f_req, blkif->st_ds_req, 588 blkif->persistent_gnt_c, 589 xen_blkif_max_pgrants); 590 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); 591 blkif->st_rd_req = 0; 592 blkif->st_wr_req = 0; 593 blkif->st_oo_req = 0; 594 blkif->st_ds_req = 0; 595 } 596 597 int xen_blkif_schedule(void *arg) 598 { 599 struct xen_blkif *blkif = arg; 600 struct xen_vbd *vbd = &blkif->vbd; 601 unsigned long timeout; 602 int ret; 603 604 xen_blkif_get(blkif); 605 606 while (!kthread_should_stop()) { 607 if (try_to_freeze()) 608 continue; 609 if (unlikely(vbd->size != vbd_sz(vbd))) 610 xen_vbd_resize(blkif); 611 612 timeout = msecs_to_jiffies(LRU_INTERVAL); 613 614 timeout = wait_event_interruptible_timeout( 615 blkif->wq, 616 blkif->waiting_reqs || kthread_should_stop(), 617 timeout); 618 if (timeout == 0) 619 goto purge_gnt_list; 620 timeout = wait_event_interruptible_timeout( 621 blkif->pending_free_wq, 622 !list_empty(&blkif->pending_free) || 623 kthread_should_stop(), 624 timeout); 625 if (timeout == 0) 626 goto purge_gnt_list; 627 628 blkif->waiting_reqs = 0; 629 smp_mb(); /* clear flag *before* checking for work */ 630 631 ret = do_block_io_op(blkif); 632 if (ret > 0) 633 blkif->waiting_reqs = 1; 634 if (ret == -EACCES) 635 wait_event_interruptible(blkif->shutdown_wq, 636 kthread_should_stop()); 637 638 purge_gnt_list: 639 if (blkif->vbd.feature_gnt_persistent && 640 time_after(jiffies, blkif->next_lru)) { 641 purge_persistent_gnt(blkif); 642 blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL); 643 } 644 645 /* Shrink if we have more than xen_blkif_max_buffer_pages */ 646 shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages); 647 648 if (log_stats && time_after(jiffies, blkif->st_print)) 649 print_stats(blkif); 650 } 651 652 /* Drain pending purge work */ 653 flush_work(&blkif->persistent_purge_work); 654 655 if (log_stats) 656 print_stats(blkif); 657 658 blkif->xenblkd = NULL; 659 xen_blkif_put(blkif); 660 661 return 0; 662 } 663 664 /* 665 * Remove persistent grants and empty the pool of free pages 666 */ 667 void xen_blkbk_free_caches(struct xen_blkif *blkif) 668 { 669 /* Free all persistent grant pages */ 670 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts)) 671 free_persistent_gnts(blkif, &blkif->persistent_gnts, 672 blkif->persistent_gnt_c); 673 674 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); 675 blkif->persistent_gnt_c = 0; 676 677 /* Since we are shutting down remove all pages from the buffer */ 678 shrink_free_pagepool(blkif, 0 /* All */); 679 } 680 681 static unsigned int xen_blkbk_unmap_prepare( 682 struct xen_blkif *blkif, 683 struct grant_page **pages, 684 unsigned int num, 685 struct gnttab_unmap_grant_ref *unmap_ops, 686 struct page **unmap_pages) 687 { 688 unsigned int i, invcount = 0; 689 690 for (i = 0; i < num; i++) { 691 if (pages[i]->persistent_gnt != NULL) { 692 put_persistent_gnt(blkif, pages[i]->persistent_gnt); 693 continue; 694 } 695 if (pages[i]->handle == BLKBACK_INVALID_HANDLE) 696 continue; 697 unmap_pages[invcount] = pages[i]->page; 698 gnttab_set_unmap_op(&unmap_ops[invcount], vaddr(pages[i]->page), 699 GNTMAP_host_map, pages[i]->handle); 700 pages[i]->handle = BLKBACK_INVALID_HANDLE; 701 invcount++; 702 } 703 704 return invcount; 705 } 706 707 static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_queue_data *data) 708 { 709 struct pending_req* pending_req = (struct pending_req*) (data->data); 710 struct xen_blkif *blkif = pending_req->blkif; 711 712 /* BUG_ON used to reproduce existing behaviour, 713 but is this the best way to deal with this? */ 714 BUG_ON(result); 715 716 put_free_pages(blkif, data->pages, data->count); 717 make_response(blkif, pending_req->id, 718 pending_req->operation, pending_req->status); 719 free_req(blkif, pending_req); 720 /* 721 * Make sure the request is freed before releasing blkif, 722 * or there could be a race between free_req and the 723 * cleanup done in xen_blkif_free during shutdown. 724 * 725 * NB: The fact that we might try to wake up pending_free_wq 726 * before drain_complete (in case there's a drain going on) 727 * it's not a problem with our current implementation 728 * because we can assure there's no thread waiting on 729 * pending_free_wq if there's a drain going on, but it has 730 * to be taken into account if the current model is changed. 731 */ 732 if (atomic_dec_and_test(&blkif->inflight) && atomic_read(&blkif->drain)) { 733 complete(&blkif->drain_complete); 734 } 735 xen_blkif_put(blkif); 736 } 737 738 static void xen_blkbk_unmap_and_respond(struct pending_req *req) 739 { 740 struct gntab_unmap_queue_data* work = &req->gnttab_unmap_data; 741 struct xen_blkif *blkif = req->blkif; 742 struct grant_page **pages = req->segments; 743 unsigned int invcount; 744 745 invcount = xen_blkbk_unmap_prepare(blkif, pages, req->nr_pages, 746 req->unmap, req->unmap_pages); 747 748 work->data = req; 749 work->done = xen_blkbk_unmap_and_respond_callback; 750 work->unmap_ops = req->unmap; 751 work->kunmap_ops = NULL; 752 work->pages = req->unmap_pages; 753 work->count = invcount; 754 755 gnttab_unmap_refs_async(&req->gnttab_unmap_data); 756 } 757 758 759 /* 760 * Unmap the grant references. 761 * 762 * This could accumulate ops up to the batch size to reduce the number 763 * of hypercalls, but since this is only used in error paths there's 764 * no real need. 765 */ 766 static void xen_blkbk_unmap(struct xen_blkif *blkif, 767 struct grant_page *pages[], 768 int num) 769 { 770 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 771 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 772 unsigned int invcount = 0; 773 int ret; 774 775 while (num) { 776 unsigned int batch = min(num, BLKIF_MAX_SEGMENTS_PER_REQUEST); 777 778 invcount = xen_blkbk_unmap_prepare(blkif, pages, batch, 779 unmap, unmap_pages); 780 if (invcount) { 781 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount); 782 BUG_ON(ret); 783 put_free_pages(blkif, unmap_pages, invcount); 784 } 785 pages += batch; 786 num -= batch; 787 } 788 } 789 790 static int xen_blkbk_map(struct xen_blkif *blkif, 791 struct grant_page *pages[], 792 int num, bool ro) 793 { 794 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 795 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 796 struct persistent_gnt *persistent_gnt = NULL; 797 phys_addr_t addr = 0; 798 int i, seg_idx, new_map_idx; 799 int segs_to_map = 0; 800 int ret = 0; 801 int last_map = 0, map_until = 0; 802 int use_persistent_gnts; 803 804 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent); 805 806 /* 807 * Fill out preq.nr_sects with proper amount of sectors, and setup 808 * assign map[..] with the PFN of the page in our domain with the 809 * corresponding grant reference for each page. 810 */ 811 again: 812 for (i = map_until; i < num; i++) { 813 uint32_t flags; 814 815 if (use_persistent_gnts) 816 persistent_gnt = get_persistent_gnt( 817 blkif, 818 pages[i]->gref); 819 820 if (persistent_gnt) { 821 /* 822 * We are using persistent grants and 823 * the grant is already mapped 824 */ 825 pages[i]->page = persistent_gnt->page; 826 pages[i]->persistent_gnt = persistent_gnt; 827 } else { 828 if (get_free_page(blkif, &pages[i]->page)) 829 goto out_of_memory; 830 addr = vaddr(pages[i]->page); 831 pages_to_gnt[segs_to_map] = pages[i]->page; 832 pages[i]->persistent_gnt = NULL; 833 flags = GNTMAP_host_map; 834 if (!use_persistent_gnts && ro) 835 flags |= GNTMAP_readonly; 836 gnttab_set_map_op(&map[segs_to_map++], addr, 837 flags, pages[i]->gref, 838 blkif->domid); 839 } 840 map_until = i + 1; 841 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST) 842 break; 843 } 844 845 if (segs_to_map) { 846 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map); 847 BUG_ON(ret); 848 } 849 850 /* 851 * Now swizzle the MFN in our domain with the MFN from the other domain 852 * so that when we access vaddr(pending_req,i) it has the contents of 853 * the page from the other domain. 854 */ 855 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) { 856 if (!pages[seg_idx]->persistent_gnt) { 857 /* This is a newly mapped grant */ 858 BUG_ON(new_map_idx >= segs_to_map); 859 if (unlikely(map[new_map_idx].status != 0)) { 860 pr_debug("invalid buffer -- could not remap it\n"); 861 put_free_pages(blkif, &pages[seg_idx]->page, 1); 862 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE; 863 ret |= 1; 864 goto next; 865 } 866 pages[seg_idx]->handle = map[new_map_idx].handle; 867 } else { 868 continue; 869 } 870 if (use_persistent_gnts && 871 blkif->persistent_gnt_c < xen_blkif_max_pgrants) { 872 /* 873 * We are using persistent grants, the grant is 874 * not mapped but we might have room for it. 875 */ 876 persistent_gnt = kmalloc(sizeof(struct persistent_gnt), 877 GFP_KERNEL); 878 if (!persistent_gnt) { 879 /* 880 * If we don't have enough memory to 881 * allocate the persistent_gnt struct 882 * map this grant non-persistenly 883 */ 884 goto next; 885 } 886 persistent_gnt->gnt = map[new_map_idx].ref; 887 persistent_gnt->handle = map[new_map_idx].handle; 888 persistent_gnt->page = pages[seg_idx]->page; 889 if (add_persistent_gnt(blkif, 890 persistent_gnt)) { 891 kfree(persistent_gnt); 892 persistent_gnt = NULL; 893 goto next; 894 } 895 pages[seg_idx]->persistent_gnt = persistent_gnt; 896 pr_debug("grant %u added to the tree of persistent grants, using %u/%u\n", 897 persistent_gnt->gnt, blkif->persistent_gnt_c, 898 xen_blkif_max_pgrants); 899 goto next; 900 } 901 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) { 902 blkif->vbd.overflow_max_grants = 1; 903 pr_debug("domain %u, device %#x is using maximum number of persistent grants\n", 904 blkif->domid, blkif->vbd.handle); 905 } 906 /* 907 * We could not map this grant persistently, so use it as 908 * a non-persistent grant. 909 */ 910 next: 911 new_map_idx++; 912 } 913 segs_to_map = 0; 914 last_map = map_until; 915 if (map_until != num) 916 goto again; 917 918 return ret; 919 920 out_of_memory: 921 pr_alert("%s: out of memory\n", __func__); 922 put_free_pages(blkif, pages_to_gnt, segs_to_map); 923 return -ENOMEM; 924 } 925 926 static int xen_blkbk_map_seg(struct pending_req *pending_req) 927 { 928 int rc; 929 930 rc = xen_blkbk_map(pending_req->blkif, pending_req->segments, 931 pending_req->nr_pages, 932 (pending_req->operation != BLKIF_OP_READ)); 933 934 return rc; 935 } 936 937 static int xen_blkbk_parse_indirect(struct blkif_request *req, 938 struct pending_req *pending_req, 939 struct seg_buf seg[], 940 struct phys_req *preq) 941 { 942 struct grant_page **pages = pending_req->indirect_pages; 943 struct xen_blkif *blkif = pending_req->blkif; 944 int indirect_grefs, rc, n, nseg, i; 945 struct blkif_request_segment *segments = NULL; 946 947 nseg = pending_req->nr_pages; 948 indirect_grefs = INDIRECT_PAGES(nseg); 949 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); 950 951 for (i = 0; i < indirect_grefs; i++) 952 pages[i]->gref = req->u.indirect.indirect_grefs[i]; 953 954 rc = xen_blkbk_map(blkif, pages, indirect_grefs, true); 955 if (rc) 956 goto unmap; 957 958 for (n = 0, i = 0; n < nseg; n++) { 959 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) { 960 /* Map indirect segments */ 961 if (segments) 962 kunmap_atomic(segments); 963 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page); 964 } 965 i = n % SEGS_PER_INDIRECT_FRAME; 966 pending_req->segments[n]->gref = segments[i].gref; 967 seg[n].nsec = segments[i].last_sect - 968 segments[i].first_sect + 1; 969 seg[n].offset = (segments[i].first_sect << 9); 970 if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) || 971 (segments[i].last_sect < segments[i].first_sect)) { 972 rc = -EINVAL; 973 goto unmap; 974 } 975 preq->nr_sects += seg[n].nsec; 976 } 977 978 unmap: 979 if (segments) 980 kunmap_atomic(segments); 981 xen_blkbk_unmap(blkif, pages, indirect_grefs); 982 return rc; 983 } 984 985 static int dispatch_discard_io(struct xen_blkif *blkif, 986 struct blkif_request *req) 987 { 988 int err = 0; 989 int status = BLKIF_RSP_OKAY; 990 struct block_device *bdev = blkif->vbd.bdev; 991 unsigned long secure; 992 struct phys_req preq; 993 994 xen_blkif_get(blkif); 995 996 preq.sector_number = req->u.discard.sector_number; 997 preq.nr_sects = req->u.discard.nr_sectors; 998 999 err = xen_vbd_translate(&preq, blkif, WRITE); 1000 if (err) { 1001 pr_warn("access denied: DISCARD [%llu->%llu] on dev=%04x\n", 1002 preq.sector_number, 1003 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice); 1004 goto fail_response; 1005 } 1006 blkif->st_ds_req++; 1007 1008 secure = (blkif->vbd.discard_secure && 1009 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? 1010 BLKDEV_DISCARD_SECURE : 0; 1011 1012 err = blkdev_issue_discard(bdev, req->u.discard.sector_number, 1013 req->u.discard.nr_sectors, 1014 GFP_KERNEL, secure); 1015 fail_response: 1016 if (err == -EOPNOTSUPP) { 1017 pr_debug("discard op failed, not supported\n"); 1018 status = BLKIF_RSP_EOPNOTSUPP; 1019 } else if (err) 1020 status = BLKIF_RSP_ERROR; 1021 1022 make_response(blkif, req->u.discard.id, req->operation, status); 1023 xen_blkif_put(blkif); 1024 return err; 1025 } 1026 1027 static int dispatch_other_io(struct xen_blkif *blkif, 1028 struct blkif_request *req, 1029 struct pending_req *pending_req) 1030 { 1031 free_req(blkif, pending_req); 1032 make_response(blkif, req->u.other.id, req->operation, 1033 BLKIF_RSP_EOPNOTSUPP); 1034 return -EIO; 1035 } 1036 1037 static void xen_blk_drain_io(struct xen_blkif *blkif) 1038 { 1039 atomic_set(&blkif->drain, 1); 1040 do { 1041 if (atomic_read(&blkif->inflight) == 0) 1042 break; 1043 wait_for_completion_interruptible_timeout( 1044 &blkif->drain_complete, HZ); 1045 1046 if (!atomic_read(&blkif->drain)) 1047 break; 1048 } while (!kthread_should_stop()); 1049 atomic_set(&blkif->drain, 0); 1050 } 1051 1052 /* 1053 * Completion callback on the bio's. Called as bh->b_end_io() 1054 */ 1055 1056 static void __end_block_io_op(struct pending_req *pending_req, int error) 1057 { 1058 /* An error fails the entire request. */ 1059 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && 1060 (error == -EOPNOTSUPP)) { 1061 pr_debug("flush diskcache op failed, not supported\n"); 1062 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); 1063 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 1064 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && 1065 (error == -EOPNOTSUPP)) { 1066 pr_debug("write barrier op failed, not supported\n"); 1067 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0); 1068 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 1069 } else if (error) { 1070 pr_debug("Buffer not up-to-date at end of operation," 1071 " error=%d\n", error); 1072 pending_req->status = BLKIF_RSP_ERROR; 1073 } 1074 1075 /* 1076 * If all of the bio's have completed it is time to unmap 1077 * the grant references associated with 'request' and provide 1078 * the proper response on the ring. 1079 */ 1080 if (atomic_dec_and_test(&pending_req->pendcnt)) 1081 xen_blkbk_unmap_and_respond(pending_req); 1082 } 1083 1084 /* 1085 * bio callback. 1086 */ 1087 static void end_block_io_op(struct bio *bio, int error) 1088 { 1089 __end_block_io_op(bio->bi_private, error); 1090 bio_put(bio); 1091 } 1092 1093 1094 1095 /* 1096 * Function to copy the from the ring buffer the 'struct blkif_request' 1097 * (which has the sectors we want, number of them, grant references, etc), 1098 * and transmute it to the block API to hand it over to the proper block disk. 1099 */ 1100 static int 1101 __do_block_io_op(struct xen_blkif *blkif) 1102 { 1103 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1104 struct blkif_request req; 1105 struct pending_req *pending_req; 1106 RING_IDX rc, rp; 1107 int more_to_do = 0; 1108 1109 rc = blk_rings->common.req_cons; 1110 rp = blk_rings->common.sring->req_prod; 1111 rmb(); /* Ensure we see queued requests up to 'rp'. */ 1112 1113 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) { 1114 rc = blk_rings->common.rsp_prod_pvt; 1115 pr_warn("Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n", 1116 rp, rc, rp - rc, blkif->vbd.pdevice); 1117 return -EACCES; 1118 } 1119 while (rc != rp) { 1120 1121 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) 1122 break; 1123 1124 if (kthread_should_stop()) { 1125 more_to_do = 1; 1126 break; 1127 } 1128 1129 pending_req = alloc_req(blkif); 1130 if (NULL == pending_req) { 1131 blkif->st_oo_req++; 1132 more_to_do = 1; 1133 break; 1134 } 1135 1136 switch (blkif->blk_protocol) { 1137 case BLKIF_PROTOCOL_NATIVE: 1138 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); 1139 break; 1140 case BLKIF_PROTOCOL_X86_32: 1141 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); 1142 break; 1143 case BLKIF_PROTOCOL_X86_64: 1144 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); 1145 break; 1146 default: 1147 BUG(); 1148 } 1149 blk_rings->common.req_cons = ++rc; /* before make_response() */ 1150 1151 /* Apply all sanity checks to /private copy/ of request. */ 1152 barrier(); 1153 1154 switch (req.operation) { 1155 case BLKIF_OP_READ: 1156 case BLKIF_OP_WRITE: 1157 case BLKIF_OP_WRITE_BARRIER: 1158 case BLKIF_OP_FLUSH_DISKCACHE: 1159 case BLKIF_OP_INDIRECT: 1160 if (dispatch_rw_block_io(blkif, &req, pending_req)) 1161 goto done; 1162 break; 1163 case BLKIF_OP_DISCARD: 1164 free_req(blkif, pending_req); 1165 if (dispatch_discard_io(blkif, &req)) 1166 goto done; 1167 break; 1168 default: 1169 if (dispatch_other_io(blkif, &req, pending_req)) 1170 goto done; 1171 break; 1172 } 1173 1174 /* Yield point for this unbounded loop. */ 1175 cond_resched(); 1176 } 1177 done: 1178 return more_to_do; 1179 } 1180 1181 static int 1182 do_block_io_op(struct xen_blkif *blkif) 1183 { 1184 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1185 int more_to_do; 1186 1187 do { 1188 more_to_do = __do_block_io_op(blkif); 1189 if (more_to_do) 1190 break; 1191 1192 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); 1193 } while (more_to_do); 1194 1195 return more_to_do; 1196 } 1197 /* 1198 * Transmutation of the 'struct blkif_request' to a proper 'struct bio' 1199 * and call the 'submit_bio' to pass it to the underlying storage. 1200 */ 1201 static int dispatch_rw_block_io(struct xen_blkif *blkif, 1202 struct blkif_request *req, 1203 struct pending_req *pending_req) 1204 { 1205 struct phys_req preq; 1206 struct seg_buf *seg = pending_req->seg; 1207 unsigned int nseg; 1208 struct bio *bio = NULL; 1209 struct bio **biolist = pending_req->biolist; 1210 int i, nbio = 0; 1211 int operation; 1212 struct blk_plug plug; 1213 bool drain = false; 1214 struct grant_page **pages = pending_req->segments; 1215 unsigned short req_operation; 1216 1217 req_operation = req->operation == BLKIF_OP_INDIRECT ? 1218 req->u.indirect.indirect_op : req->operation; 1219 if ((req->operation == BLKIF_OP_INDIRECT) && 1220 (req_operation != BLKIF_OP_READ) && 1221 (req_operation != BLKIF_OP_WRITE)) { 1222 pr_debug("Invalid indirect operation (%u)\n", req_operation); 1223 goto fail_response; 1224 } 1225 1226 switch (req_operation) { 1227 case BLKIF_OP_READ: 1228 blkif->st_rd_req++; 1229 operation = READ; 1230 break; 1231 case BLKIF_OP_WRITE: 1232 blkif->st_wr_req++; 1233 operation = WRITE_ODIRECT; 1234 break; 1235 case BLKIF_OP_WRITE_BARRIER: 1236 drain = true; 1237 case BLKIF_OP_FLUSH_DISKCACHE: 1238 blkif->st_f_req++; 1239 operation = WRITE_FLUSH; 1240 break; 1241 default: 1242 operation = 0; /* make gcc happy */ 1243 goto fail_response; 1244 break; 1245 } 1246 1247 /* Check that the number of segments is sane. */ 1248 nseg = req->operation == BLKIF_OP_INDIRECT ? 1249 req->u.indirect.nr_segments : req->u.rw.nr_segments; 1250 1251 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || 1252 unlikely((req->operation != BLKIF_OP_INDIRECT) && 1253 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) || 1254 unlikely((req->operation == BLKIF_OP_INDIRECT) && 1255 (nseg > MAX_INDIRECT_SEGMENTS))) { 1256 pr_debug("Bad number of segments in request (%d)\n", nseg); 1257 /* Haven't submitted any bio's yet. */ 1258 goto fail_response; 1259 } 1260 1261 preq.nr_sects = 0; 1262 1263 pending_req->blkif = blkif; 1264 pending_req->id = req->u.rw.id; 1265 pending_req->operation = req_operation; 1266 pending_req->status = BLKIF_RSP_OKAY; 1267 pending_req->nr_pages = nseg; 1268 1269 if (req->operation != BLKIF_OP_INDIRECT) { 1270 preq.dev = req->u.rw.handle; 1271 preq.sector_number = req->u.rw.sector_number; 1272 for (i = 0; i < nseg; i++) { 1273 pages[i]->gref = req->u.rw.seg[i].gref; 1274 seg[i].nsec = req->u.rw.seg[i].last_sect - 1275 req->u.rw.seg[i].first_sect + 1; 1276 seg[i].offset = (req->u.rw.seg[i].first_sect << 9); 1277 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || 1278 (req->u.rw.seg[i].last_sect < 1279 req->u.rw.seg[i].first_sect)) 1280 goto fail_response; 1281 preq.nr_sects += seg[i].nsec; 1282 } 1283 } else { 1284 preq.dev = req->u.indirect.handle; 1285 preq.sector_number = req->u.indirect.sector_number; 1286 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq)) 1287 goto fail_response; 1288 } 1289 1290 if (xen_vbd_translate(&preq, blkif, operation) != 0) { 1291 pr_debug("access denied: %s of [%llu,%llu] on dev=%04x\n", 1292 operation == READ ? "read" : "write", 1293 preq.sector_number, 1294 preq.sector_number + preq.nr_sects, 1295 blkif->vbd.pdevice); 1296 goto fail_response; 1297 } 1298 1299 /* 1300 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev 1301 * is set there. 1302 */ 1303 for (i = 0; i < nseg; i++) { 1304 if (((int)preq.sector_number|(int)seg[i].nsec) & 1305 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { 1306 pr_debug("Misaligned I/O request from domain %d\n", 1307 blkif->domid); 1308 goto fail_response; 1309 } 1310 } 1311 1312 /* Wait on all outstanding I/O's and once that has been completed 1313 * issue the WRITE_FLUSH. 1314 */ 1315 if (drain) 1316 xen_blk_drain_io(pending_req->blkif); 1317 1318 /* 1319 * If we have failed at this point, we need to undo the M2P override, 1320 * set gnttab_set_unmap_op on all of the grant references and perform 1321 * the hypercall to unmap the grants - that is all done in 1322 * xen_blkbk_unmap. 1323 */ 1324 if (xen_blkbk_map_seg(pending_req)) 1325 goto fail_flush; 1326 1327 /* 1328 * This corresponding xen_blkif_put is done in __end_block_io_op, or 1329 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. 1330 */ 1331 xen_blkif_get(blkif); 1332 atomic_inc(&blkif->inflight); 1333 1334 for (i = 0; i < nseg; i++) { 1335 while ((bio == NULL) || 1336 (bio_add_page(bio, 1337 pages[i]->page, 1338 seg[i].nsec << 9, 1339 seg[i].offset) == 0)) { 1340 1341 int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES); 1342 bio = bio_alloc(GFP_KERNEL, nr_iovecs); 1343 if (unlikely(bio == NULL)) 1344 goto fail_put_bio; 1345 1346 biolist[nbio++] = bio; 1347 bio->bi_bdev = preq.bdev; 1348 bio->bi_private = pending_req; 1349 bio->bi_end_io = end_block_io_op; 1350 bio->bi_iter.bi_sector = preq.sector_number; 1351 } 1352 1353 preq.sector_number += seg[i].nsec; 1354 } 1355 1356 /* This will be hit if the operation was a flush or discard. */ 1357 if (!bio) { 1358 BUG_ON(operation != WRITE_FLUSH); 1359 1360 bio = bio_alloc(GFP_KERNEL, 0); 1361 if (unlikely(bio == NULL)) 1362 goto fail_put_bio; 1363 1364 biolist[nbio++] = bio; 1365 bio->bi_bdev = preq.bdev; 1366 bio->bi_private = pending_req; 1367 bio->bi_end_io = end_block_io_op; 1368 } 1369 1370 atomic_set(&pending_req->pendcnt, nbio); 1371 blk_start_plug(&plug); 1372 1373 for (i = 0; i < nbio; i++) 1374 submit_bio(operation, biolist[i]); 1375 1376 /* Let the I/Os go.. */ 1377 blk_finish_plug(&plug); 1378 1379 if (operation == READ) 1380 blkif->st_rd_sect += preq.nr_sects; 1381 else if (operation & WRITE) 1382 blkif->st_wr_sect += preq.nr_sects; 1383 1384 return 0; 1385 1386 fail_flush: 1387 xen_blkbk_unmap(blkif, pending_req->segments, 1388 pending_req->nr_pages); 1389 fail_response: 1390 /* Haven't submitted any bio's yet. */ 1391 make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR); 1392 free_req(blkif, pending_req); 1393 msleep(1); /* back off a bit */ 1394 return -EIO; 1395 1396 fail_put_bio: 1397 for (i = 0; i < nbio; i++) 1398 bio_put(biolist[i]); 1399 atomic_set(&pending_req->pendcnt, 1); 1400 __end_block_io_op(pending_req, -EINVAL); 1401 msleep(1); /* back off a bit */ 1402 return -EIO; 1403 } 1404 1405 1406 1407 /* 1408 * Put a response on the ring on how the operation fared. 1409 */ 1410 static void make_response(struct xen_blkif *blkif, u64 id, 1411 unsigned short op, int st) 1412 { 1413 struct blkif_response resp; 1414 unsigned long flags; 1415 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1416 int notify; 1417 1418 resp.id = id; 1419 resp.operation = op; 1420 resp.status = st; 1421 1422 spin_lock_irqsave(&blkif->blk_ring_lock, flags); 1423 /* Place on the response ring for the relevant domain. */ 1424 switch (blkif->blk_protocol) { 1425 case BLKIF_PROTOCOL_NATIVE: 1426 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), 1427 &resp, sizeof(resp)); 1428 break; 1429 case BLKIF_PROTOCOL_X86_32: 1430 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), 1431 &resp, sizeof(resp)); 1432 break; 1433 case BLKIF_PROTOCOL_X86_64: 1434 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), 1435 &resp, sizeof(resp)); 1436 break; 1437 default: 1438 BUG(); 1439 } 1440 blk_rings->common.rsp_prod_pvt++; 1441 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); 1442 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); 1443 if (notify) 1444 notify_remote_via_irq(blkif->irq); 1445 } 1446 1447 static int __init xen_blkif_init(void) 1448 { 1449 int rc = 0; 1450 1451 if (!xen_domain()) 1452 return -ENODEV; 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"); 1470