1 /****************************************************************************** 2 * 3 * Back-end of the driver for virtual block devices. This portion of the 4 * driver exports a 'unified' block-device interface that can be accessed 5 * by any operating system that implements a compatible front end. A 6 * reference front-end implementation can be found in: 7 * drivers/block/xen-blkfront.c 8 * 9 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand 10 * Copyright (c) 2005, Christopher Clark 11 * 12 * This program is free software; you can redistribute it and/or 13 * modify it under the terms of the GNU General Public License version 2 14 * as published by the Free Software Foundation; or, when distributed 15 * separately from the Linux kernel or incorporated into other 16 * software packages, subject to the following license: 17 * 18 * Permission is hereby granted, free of charge, to any person obtaining a copy 19 * of this source file (the "Software"), to deal in the Software without 20 * restriction, including without limitation the rights to use, copy, modify, 21 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 22 * and to permit persons to whom the Software is furnished to do so, subject to 23 * the following conditions: 24 * 25 * The above copyright notice and this permission notice shall be included in 26 * all copies or substantial portions of the Software. 27 * 28 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 29 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 30 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 31 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 32 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 33 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 34 * IN THE SOFTWARE. 35 */ 36 37 #include <linux/spinlock.h> 38 #include <linux/kthread.h> 39 #include <linux/list.h> 40 #include <linux/delay.h> 41 #include <linux/freezer.h> 42 #include <linux/bitmap.h> 43 44 #include <xen/events.h> 45 #include <xen/page.h> 46 #include <xen/xen.h> 47 #include <asm/xen/hypervisor.h> 48 #include <asm/xen/hypercall.h> 49 #include <xen/balloon.h> 50 #include "common.h" 51 52 /* 53 * Maximum number of unused free pages to keep in the internal buffer. 54 * Setting this to a value too low will reduce memory used in each backend, 55 * but can have a performance penalty. 56 * 57 * A sane value is xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST, but can 58 * be set to a lower value that might degrade performance on some intensive 59 * IO workloads. 60 */ 61 62 static int xen_blkif_max_buffer_pages = 1024; 63 module_param_named(max_buffer_pages, xen_blkif_max_buffer_pages, int, 0644); 64 MODULE_PARM_DESC(max_buffer_pages, 65 "Maximum number of free pages to keep in each block backend buffer"); 66 67 /* 68 * Maximum number of grants to map persistently in blkback. For maximum 69 * performance this should be the total numbers of grants that can be used 70 * to fill the ring, but since this might become too high, specially with 71 * the use of indirect descriptors, we set it to a value that provides good 72 * performance without using too much memory. 73 * 74 * When the list of persistent grants is full we clean it up using a LRU 75 * algorithm. 76 */ 77 78 static int xen_blkif_max_pgrants = 1056; 79 module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644); 80 MODULE_PARM_DESC(max_persistent_grants, 81 "Maximum number of grants to map persistently"); 82 83 /* 84 * The LRU mechanism to clean the lists of persistent grants needs to 85 * be executed periodically. The time interval between consecutive executions 86 * of the purge mechanism is set in ms. 87 */ 88 #define LRU_INTERVAL 100 89 90 /* 91 * When the persistent grants list is full we will remove unused grants 92 * from the list. The percent number of grants to be removed at each LRU 93 * execution. 94 */ 95 #define LRU_PERCENT_CLEAN 5 96 97 /* Run-time switchable: /sys/module/blkback/parameters/ */ 98 static unsigned int log_stats; 99 module_param(log_stats, int, 0644); 100 101 #define BLKBACK_INVALID_HANDLE (~0) 102 103 /* Number of free pages to remove on each call to free_xenballooned_pages */ 104 #define NUM_BATCH_FREE_PAGES 10 105 106 static inline int get_free_page(struct xen_blkif *blkif, struct page **page) 107 { 108 unsigned long flags; 109 110 spin_lock_irqsave(&blkif->free_pages_lock, flags); 111 if (list_empty(&blkif->free_pages)) { 112 BUG_ON(blkif->free_pages_num != 0); 113 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 114 return alloc_xenballooned_pages(1, page, false); 115 } 116 BUG_ON(blkif->free_pages_num == 0); 117 page[0] = list_first_entry(&blkif->free_pages, struct page, lru); 118 list_del(&page[0]->lru); 119 blkif->free_pages_num--; 120 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 121 122 return 0; 123 } 124 125 static inline void put_free_pages(struct xen_blkif *blkif, struct page **page, 126 int num) 127 { 128 unsigned long flags; 129 int i; 130 131 spin_lock_irqsave(&blkif->free_pages_lock, flags); 132 for (i = 0; i < num; i++) 133 list_add(&page[i]->lru, &blkif->free_pages); 134 blkif->free_pages_num += num; 135 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 136 } 137 138 static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num) 139 { 140 /* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */ 141 struct page *page[NUM_BATCH_FREE_PAGES]; 142 unsigned int num_pages = 0; 143 unsigned long flags; 144 145 spin_lock_irqsave(&blkif->free_pages_lock, flags); 146 while (blkif->free_pages_num > num) { 147 BUG_ON(list_empty(&blkif->free_pages)); 148 page[num_pages] = list_first_entry(&blkif->free_pages, 149 struct page, lru); 150 list_del(&page[num_pages]->lru); 151 blkif->free_pages_num--; 152 if (++num_pages == NUM_BATCH_FREE_PAGES) { 153 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 154 free_xenballooned_pages(num_pages, page); 155 spin_lock_irqsave(&blkif->free_pages_lock, flags); 156 num_pages = 0; 157 } 158 } 159 spin_unlock_irqrestore(&blkif->free_pages_lock, flags); 160 if (num_pages != 0) 161 free_xenballooned_pages(num_pages, page); 162 } 163 164 #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page))) 165 166 static int do_block_io_op(struct xen_blkif *blkif); 167 static int dispatch_rw_block_io(struct xen_blkif *blkif, 168 struct blkif_request *req, 169 struct pending_req *pending_req); 170 static void make_response(struct xen_blkif *blkif, u64 id, 171 unsigned short op, int st); 172 173 #define foreach_grant_safe(pos, n, rbtree, node) \ 174 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \ 175 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \ 176 &(pos)->node != NULL; \ 177 (pos) = container_of(n, typeof(*(pos)), node), \ 178 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL) 179 180 181 /* 182 * We don't need locking around the persistent grant helpers 183 * because blkback uses a single-thread for each backed, so we 184 * can be sure that this functions will never be called recursively. 185 * 186 * The only exception to that is put_persistent_grant, that can be called 187 * from interrupt context (by xen_blkbk_unmap), so we have to use atomic 188 * bit operations to modify the flags of a persistent grant and to count 189 * the number of used grants. 190 */ 191 static int add_persistent_gnt(struct xen_blkif *blkif, 192 struct persistent_gnt *persistent_gnt) 193 { 194 struct rb_node **new = NULL, *parent = NULL; 195 struct persistent_gnt *this; 196 197 if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) { 198 if (!blkif->vbd.overflow_max_grants) 199 blkif->vbd.overflow_max_grants = 1; 200 return -EBUSY; 201 } 202 /* Figure out where to put new node */ 203 new = &blkif->persistent_gnts.rb_node; 204 while (*new) { 205 this = container_of(*new, struct persistent_gnt, node); 206 207 parent = *new; 208 if (persistent_gnt->gnt < this->gnt) 209 new = &((*new)->rb_left); 210 else if (persistent_gnt->gnt > this->gnt) 211 new = &((*new)->rb_right); 212 else { 213 pr_alert_ratelimited(DRV_PFX " trying to add a gref that's already in the tree\n"); 214 return -EINVAL; 215 } 216 } 217 218 bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE); 219 set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); 220 /* Add new node and rebalance tree. */ 221 rb_link_node(&(persistent_gnt->node), parent, new); 222 rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts); 223 blkif->persistent_gnt_c++; 224 atomic_inc(&blkif->persistent_gnt_in_use); 225 return 0; 226 } 227 228 static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif, 229 grant_ref_t gref) 230 { 231 struct persistent_gnt *data; 232 struct rb_node *node = NULL; 233 234 node = blkif->persistent_gnts.rb_node; 235 while (node) { 236 data = container_of(node, struct persistent_gnt, node); 237 238 if (gref < data->gnt) 239 node = node->rb_left; 240 else if (gref > data->gnt) 241 node = node->rb_right; 242 else { 243 if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) { 244 pr_alert_ratelimited(DRV_PFX " requesting a grant already in use\n"); 245 return NULL; 246 } 247 set_bit(PERSISTENT_GNT_ACTIVE, data->flags); 248 atomic_inc(&blkif->persistent_gnt_in_use); 249 return data; 250 } 251 } 252 return NULL; 253 } 254 255 static void put_persistent_gnt(struct xen_blkif *blkif, 256 struct persistent_gnt *persistent_gnt) 257 { 258 if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) 259 pr_alert_ratelimited(DRV_PFX " freeing a grant already unused"); 260 set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); 261 clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags); 262 atomic_dec(&blkif->persistent_gnt_in_use); 263 } 264 265 static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root, 266 unsigned int num) 267 { 268 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 269 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 270 struct persistent_gnt *persistent_gnt; 271 struct rb_node *n; 272 int ret = 0; 273 int segs_to_unmap = 0; 274 275 foreach_grant_safe(persistent_gnt, n, root, node) { 276 BUG_ON(persistent_gnt->handle == 277 BLKBACK_INVALID_HANDLE); 278 gnttab_set_unmap_op(&unmap[segs_to_unmap], 279 (unsigned long) pfn_to_kaddr(page_to_pfn( 280 persistent_gnt->page)), 281 GNTMAP_host_map, 282 persistent_gnt->handle); 283 284 pages[segs_to_unmap] = persistent_gnt->page; 285 286 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST || 287 !rb_next(&persistent_gnt->node)) { 288 ret = gnttab_unmap_refs(unmap, NULL, pages, 289 segs_to_unmap); 290 BUG_ON(ret); 291 put_free_pages(blkif, pages, segs_to_unmap); 292 segs_to_unmap = 0; 293 } 294 295 rb_erase(&persistent_gnt->node, root); 296 kfree(persistent_gnt); 297 num--; 298 } 299 BUG_ON(num != 0); 300 } 301 302 static void unmap_purged_grants(struct work_struct *work) 303 { 304 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 305 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 306 struct persistent_gnt *persistent_gnt; 307 int ret, segs_to_unmap = 0; 308 struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work); 309 310 while(!list_empty(&blkif->persistent_purge_list)) { 311 persistent_gnt = list_first_entry(&blkif->persistent_purge_list, 312 struct persistent_gnt, 313 remove_node); 314 list_del(&persistent_gnt->remove_node); 315 316 gnttab_set_unmap_op(&unmap[segs_to_unmap], 317 vaddr(persistent_gnt->page), 318 GNTMAP_host_map, 319 persistent_gnt->handle); 320 321 pages[segs_to_unmap] = persistent_gnt->page; 322 323 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) { 324 ret = gnttab_unmap_refs(unmap, NULL, pages, 325 segs_to_unmap); 326 BUG_ON(ret); 327 put_free_pages(blkif, pages, segs_to_unmap); 328 segs_to_unmap = 0; 329 } 330 kfree(persistent_gnt); 331 } 332 if (segs_to_unmap > 0) { 333 ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap); 334 BUG_ON(ret); 335 put_free_pages(blkif, pages, segs_to_unmap); 336 } 337 } 338 339 static void purge_persistent_gnt(struct xen_blkif *blkif) 340 { 341 struct persistent_gnt *persistent_gnt; 342 struct rb_node *n; 343 unsigned int num_clean, total; 344 bool scan_used = false, clean_used = false; 345 struct rb_root *root; 346 347 if (blkif->persistent_gnt_c < xen_blkif_max_pgrants || 348 (blkif->persistent_gnt_c == xen_blkif_max_pgrants && 349 !blkif->vbd.overflow_max_grants)) { 350 return; 351 } 352 353 if (work_pending(&blkif->persistent_purge_work)) { 354 pr_alert_ratelimited(DRV_PFX "Scheduled work from previous purge is still pending, cannot purge list\n"); 355 return; 356 } 357 358 num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN; 359 num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean; 360 num_clean = min(blkif->persistent_gnt_c, num_clean); 361 if ((num_clean == 0) || 362 (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use)))) 363 return; 364 365 /* 366 * At this point, we can assure that there will be no calls 367 * to get_persistent_grant (because we are executing this code from 368 * xen_blkif_schedule), there can only be calls to put_persistent_gnt, 369 * which means that the number of currently used grants will go down, 370 * but never up, so we will always be able to remove the requested 371 * number of grants. 372 */ 373 374 total = num_clean; 375 376 pr_debug(DRV_PFX "Going to purge %u persistent grants\n", num_clean); 377 378 INIT_LIST_HEAD(&blkif->persistent_purge_list); 379 root = &blkif->persistent_gnts; 380 purge_list: 381 foreach_grant_safe(persistent_gnt, n, root, node) { 382 BUG_ON(persistent_gnt->handle == 383 BLKBACK_INVALID_HANDLE); 384 385 if (clean_used) { 386 clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); 387 continue; 388 } 389 390 if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) 391 continue; 392 if (!scan_used && 393 (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags))) 394 continue; 395 396 rb_erase(&persistent_gnt->node, root); 397 list_add(&persistent_gnt->remove_node, 398 &blkif->persistent_purge_list); 399 if (--num_clean == 0) 400 goto finished; 401 } 402 /* 403 * If we get here it means we also need to start cleaning 404 * grants that were used since last purge in order to cope 405 * with the requested num 406 */ 407 if (!scan_used && !clean_used) { 408 pr_debug(DRV_PFX "Still missing %u purged frames\n", num_clean); 409 scan_used = true; 410 goto purge_list; 411 } 412 finished: 413 if (!clean_used) { 414 pr_debug(DRV_PFX "Finished scanning for grants to clean, removing used flag\n"); 415 clean_used = true; 416 goto purge_list; 417 } 418 419 blkif->persistent_gnt_c -= (total - num_clean); 420 blkif->vbd.overflow_max_grants = 0; 421 422 /* We can defer this work */ 423 INIT_WORK(&blkif->persistent_purge_work, unmap_purged_grants); 424 schedule_work(&blkif->persistent_purge_work); 425 pr_debug(DRV_PFX "Purged %u/%u\n", (total - num_clean), total); 426 return; 427 } 428 429 /* 430 * Retrieve from the 'pending_reqs' a free pending_req structure to be used. 431 */ 432 static struct pending_req *alloc_req(struct xen_blkif *blkif) 433 { 434 struct pending_req *req = NULL; 435 unsigned long flags; 436 437 spin_lock_irqsave(&blkif->pending_free_lock, flags); 438 if (!list_empty(&blkif->pending_free)) { 439 req = list_entry(blkif->pending_free.next, struct pending_req, 440 free_list); 441 list_del(&req->free_list); 442 } 443 spin_unlock_irqrestore(&blkif->pending_free_lock, flags); 444 return req; 445 } 446 447 /* 448 * Return the 'pending_req' structure back to the freepool. We also 449 * wake up the thread if it was waiting for a free page. 450 */ 451 static void free_req(struct xen_blkif *blkif, struct pending_req *req) 452 { 453 unsigned long flags; 454 int was_empty; 455 456 spin_lock_irqsave(&blkif->pending_free_lock, flags); 457 was_empty = list_empty(&blkif->pending_free); 458 list_add(&req->free_list, &blkif->pending_free); 459 spin_unlock_irqrestore(&blkif->pending_free_lock, flags); 460 if (was_empty) 461 wake_up(&blkif->pending_free_wq); 462 } 463 464 /* 465 * Routines for managing virtual block devices (vbds). 466 */ 467 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, 468 int operation) 469 { 470 struct xen_vbd *vbd = &blkif->vbd; 471 int rc = -EACCES; 472 473 if ((operation != READ) && vbd->readonly) 474 goto out; 475 476 if (likely(req->nr_sects)) { 477 blkif_sector_t end = req->sector_number + req->nr_sects; 478 479 if (unlikely(end < req->sector_number)) 480 goto out; 481 if (unlikely(end > vbd_sz(vbd))) 482 goto out; 483 } 484 485 req->dev = vbd->pdevice; 486 req->bdev = vbd->bdev; 487 rc = 0; 488 489 out: 490 return rc; 491 } 492 493 static void xen_vbd_resize(struct xen_blkif *blkif) 494 { 495 struct xen_vbd *vbd = &blkif->vbd; 496 struct xenbus_transaction xbt; 497 int err; 498 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); 499 unsigned long long new_size = vbd_sz(vbd); 500 501 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n", 502 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); 503 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size); 504 vbd->size = new_size; 505 again: 506 err = xenbus_transaction_start(&xbt); 507 if (err) { 508 pr_warn(DRV_PFX "Error starting transaction"); 509 return; 510 } 511 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 512 (unsigned long long)vbd_sz(vbd)); 513 if (err) { 514 pr_warn(DRV_PFX "Error writing new size"); 515 goto abort; 516 } 517 /* 518 * Write the current state; we will use this to synchronize 519 * the front-end. If the current state is "connected" the 520 * front-end will get the new size information online. 521 */ 522 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); 523 if (err) { 524 pr_warn(DRV_PFX "Error writing the state"); 525 goto abort; 526 } 527 528 err = xenbus_transaction_end(xbt, 0); 529 if (err == -EAGAIN) 530 goto again; 531 if (err) 532 pr_warn(DRV_PFX "Error ending transaction"); 533 return; 534 abort: 535 xenbus_transaction_end(xbt, 1); 536 } 537 538 /* 539 * Notification from the guest OS. 540 */ 541 static void blkif_notify_work(struct xen_blkif *blkif) 542 { 543 blkif->waiting_reqs = 1; 544 wake_up(&blkif->wq); 545 } 546 547 irqreturn_t xen_blkif_be_int(int irq, void *dev_id) 548 { 549 blkif_notify_work(dev_id); 550 return IRQ_HANDLED; 551 } 552 553 /* 554 * SCHEDULER FUNCTIONS 555 */ 556 557 static void print_stats(struct xen_blkif *blkif) 558 { 559 pr_info("xen-blkback (%s): oo %3llu | rd %4llu | wr %4llu | f %4llu" 560 " | ds %4llu | pg: %4u/%4d\n", 561 current->comm, blkif->st_oo_req, 562 blkif->st_rd_req, blkif->st_wr_req, 563 blkif->st_f_req, blkif->st_ds_req, 564 blkif->persistent_gnt_c, 565 xen_blkif_max_pgrants); 566 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); 567 blkif->st_rd_req = 0; 568 blkif->st_wr_req = 0; 569 blkif->st_oo_req = 0; 570 blkif->st_ds_req = 0; 571 } 572 573 int xen_blkif_schedule(void *arg) 574 { 575 struct xen_blkif *blkif = arg; 576 struct xen_vbd *vbd = &blkif->vbd; 577 unsigned long timeout; 578 int ret; 579 580 xen_blkif_get(blkif); 581 582 while (!kthread_should_stop()) { 583 if (try_to_freeze()) 584 continue; 585 if (unlikely(vbd->size != vbd_sz(vbd))) 586 xen_vbd_resize(blkif); 587 588 timeout = msecs_to_jiffies(LRU_INTERVAL); 589 590 timeout = wait_event_interruptible_timeout( 591 blkif->wq, 592 blkif->waiting_reqs || kthread_should_stop(), 593 timeout); 594 if (timeout == 0) 595 goto purge_gnt_list; 596 timeout = wait_event_interruptible_timeout( 597 blkif->pending_free_wq, 598 !list_empty(&blkif->pending_free) || 599 kthread_should_stop(), 600 timeout); 601 if (timeout == 0) 602 goto purge_gnt_list; 603 604 blkif->waiting_reqs = 0; 605 smp_mb(); /* clear flag *before* checking for work */ 606 607 ret = do_block_io_op(blkif); 608 if (ret > 0) 609 blkif->waiting_reqs = 1; 610 if (ret == -EACCES) 611 wait_event_interruptible(blkif->shutdown_wq, 612 kthread_should_stop()); 613 614 purge_gnt_list: 615 if (blkif->vbd.feature_gnt_persistent && 616 time_after(jiffies, blkif->next_lru)) { 617 purge_persistent_gnt(blkif); 618 blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL); 619 } 620 621 /* Shrink if we have more than xen_blkif_max_buffer_pages */ 622 shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages); 623 624 if (log_stats && time_after(jiffies, blkif->st_print)) 625 print_stats(blkif); 626 } 627 628 /* Since we are shutting down remove all pages from the buffer */ 629 shrink_free_pagepool(blkif, 0 /* All */); 630 631 /* Free all persistent grant pages */ 632 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts)) 633 free_persistent_gnts(blkif, &blkif->persistent_gnts, 634 blkif->persistent_gnt_c); 635 636 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); 637 blkif->persistent_gnt_c = 0; 638 639 if (log_stats) 640 print_stats(blkif); 641 642 blkif->xenblkd = NULL; 643 xen_blkif_put(blkif); 644 645 return 0; 646 } 647 648 /* 649 * Unmap the grant references, and also remove the M2P over-rides 650 * used in the 'pending_req'. 651 */ 652 static void xen_blkbk_unmap(struct xen_blkif *blkif, 653 struct grant_page *pages[], 654 int num) 655 { 656 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 657 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 658 unsigned int i, invcount = 0; 659 int ret; 660 661 for (i = 0; i < num; i++) { 662 if (pages[i]->persistent_gnt != NULL) { 663 put_persistent_gnt(blkif, pages[i]->persistent_gnt); 664 continue; 665 } 666 if (pages[i]->handle == BLKBACK_INVALID_HANDLE) 667 continue; 668 unmap_pages[invcount] = pages[i]->page; 669 gnttab_set_unmap_op(&unmap[invcount], vaddr(pages[i]->page), 670 GNTMAP_host_map, pages[i]->handle); 671 pages[i]->handle = BLKBACK_INVALID_HANDLE; 672 if (++invcount == BLKIF_MAX_SEGMENTS_PER_REQUEST) { 673 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, 674 invcount); 675 BUG_ON(ret); 676 put_free_pages(blkif, unmap_pages, invcount); 677 invcount = 0; 678 } 679 } 680 if (invcount) { 681 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount); 682 BUG_ON(ret); 683 put_free_pages(blkif, unmap_pages, invcount); 684 } 685 } 686 687 static int xen_blkbk_map(struct xen_blkif *blkif, 688 struct grant_page *pages[], 689 int num, bool ro) 690 { 691 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 692 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 693 struct persistent_gnt *persistent_gnt = NULL; 694 phys_addr_t addr = 0; 695 int i, seg_idx, new_map_idx; 696 int segs_to_map = 0; 697 int ret = 0; 698 int last_map = 0, map_until = 0; 699 int use_persistent_gnts; 700 701 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent); 702 703 /* 704 * Fill out preq.nr_sects with proper amount of sectors, and setup 705 * assign map[..] with the PFN of the page in our domain with the 706 * corresponding grant reference for each page. 707 */ 708 again: 709 for (i = map_until; i < num; i++) { 710 uint32_t flags; 711 712 if (use_persistent_gnts) 713 persistent_gnt = get_persistent_gnt( 714 blkif, 715 pages[i]->gref); 716 717 if (persistent_gnt) { 718 /* 719 * We are using persistent grants and 720 * the grant is already mapped 721 */ 722 pages[i]->page = persistent_gnt->page; 723 pages[i]->persistent_gnt = persistent_gnt; 724 } else { 725 if (get_free_page(blkif, &pages[i]->page)) 726 goto out_of_memory; 727 addr = vaddr(pages[i]->page); 728 pages_to_gnt[segs_to_map] = pages[i]->page; 729 pages[i]->persistent_gnt = NULL; 730 flags = GNTMAP_host_map; 731 if (!use_persistent_gnts && ro) 732 flags |= GNTMAP_readonly; 733 gnttab_set_map_op(&map[segs_to_map++], addr, 734 flags, pages[i]->gref, 735 blkif->domid); 736 } 737 map_until = i + 1; 738 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST) 739 break; 740 } 741 742 if (segs_to_map) { 743 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map); 744 BUG_ON(ret); 745 } 746 747 /* 748 * Now swizzle the MFN in our domain with the MFN from the other domain 749 * so that when we access vaddr(pending_req,i) it has the contents of 750 * the page from the other domain. 751 */ 752 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) { 753 if (!pages[seg_idx]->persistent_gnt) { 754 /* This is a newly mapped grant */ 755 BUG_ON(new_map_idx >= segs_to_map); 756 if (unlikely(map[new_map_idx].status != 0)) { 757 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n"); 758 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE; 759 ret |= 1; 760 goto next; 761 } 762 pages[seg_idx]->handle = map[new_map_idx].handle; 763 } else { 764 continue; 765 } 766 if (use_persistent_gnts && 767 blkif->persistent_gnt_c < xen_blkif_max_pgrants) { 768 /* 769 * We are using persistent grants, the grant is 770 * not mapped but we might have room for it. 771 */ 772 persistent_gnt = kmalloc(sizeof(struct persistent_gnt), 773 GFP_KERNEL); 774 if (!persistent_gnt) { 775 /* 776 * If we don't have enough memory to 777 * allocate the persistent_gnt struct 778 * map this grant non-persistenly 779 */ 780 goto next; 781 } 782 persistent_gnt->gnt = map[new_map_idx].ref; 783 persistent_gnt->handle = map[new_map_idx].handle; 784 persistent_gnt->page = pages[seg_idx]->page; 785 if (add_persistent_gnt(blkif, 786 persistent_gnt)) { 787 kfree(persistent_gnt); 788 persistent_gnt = NULL; 789 goto next; 790 } 791 pages[seg_idx]->persistent_gnt = persistent_gnt; 792 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n", 793 persistent_gnt->gnt, blkif->persistent_gnt_c, 794 xen_blkif_max_pgrants); 795 goto next; 796 } 797 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) { 798 blkif->vbd.overflow_max_grants = 1; 799 pr_debug(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n", 800 blkif->domid, blkif->vbd.handle); 801 } 802 /* 803 * We could not map this grant persistently, so use it as 804 * a non-persistent grant. 805 */ 806 next: 807 new_map_idx++; 808 } 809 segs_to_map = 0; 810 last_map = map_until; 811 if (map_until != num) 812 goto again; 813 814 return ret; 815 816 out_of_memory: 817 pr_alert(DRV_PFX "%s: out of memory\n", __func__); 818 put_free_pages(blkif, pages_to_gnt, segs_to_map); 819 return -ENOMEM; 820 } 821 822 static int xen_blkbk_map_seg(struct pending_req *pending_req) 823 { 824 int rc; 825 826 rc = xen_blkbk_map(pending_req->blkif, pending_req->segments, 827 pending_req->nr_pages, 828 (pending_req->operation != BLKIF_OP_READ)); 829 830 return rc; 831 } 832 833 static int xen_blkbk_parse_indirect(struct blkif_request *req, 834 struct pending_req *pending_req, 835 struct seg_buf seg[], 836 struct phys_req *preq) 837 { 838 struct grant_page **pages = pending_req->indirect_pages; 839 struct xen_blkif *blkif = pending_req->blkif; 840 int indirect_grefs, rc, n, nseg, i; 841 struct blkif_request_segment_aligned *segments = NULL; 842 843 nseg = pending_req->nr_pages; 844 indirect_grefs = INDIRECT_PAGES(nseg); 845 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); 846 847 for (i = 0; i < indirect_grefs; i++) 848 pages[i]->gref = req->u.indirect.indirect_grefs[i]; 849 850 rc = xen_blkbk_map(blkif, pages, indirect_grefs, true); 851 if (rc) 852 goto unmap; 853 854 for (n = 0, i = 0; n < nseg; n++) { 855 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) { 856 /* Map indirect segments */ 857 if (segments) 858 kunmap_atomic(segments); 859 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page); 860 } 861 i = n % SEGS_PER_INDIRECT_FRAME; 862 pending_req->segments[n]->gref = segments[i].gref; 863 seg[n].nsec = segments[i].last_sect - 864 segments[i].first_sect + 1; 865 seg[n].offset = (segments[i].first_sect << 9); 866 if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) || 867 (segments[i].last_sect < segments[i].first_sect)) { 868 rc = -EINVAL; 869 goto unmap; 870 } 871 preq->nr_sects += seg[n].nsec; 872 } 873 874 unmap: 875 if (segments) 876 kunmap_atomic(segments); 877 xen_blkbk_unmap(blkif, pages, indirect_grefs); 878 return rc; 879 } 880 881 static int dispatch_discard_io(struct xen_blkif *blkif, 882 struct blkif_request *req) 883 { 884 int err = 0; 885 int status = BLKIF_RSP_OKAY; 886 struct block_device *bdev = blkif->vbd.bdev; 887 unsigned long secure; 888 struct phys_req preq; 889 890 xen_blkif_get(blkif); 891 892 preq.sector_number = req->u.discard.sector_number; 893 preq.nr_sects = req->u.discard.nr_sectors; 894 895 err = xen_vbd_translate(&preq, blkif, WRITE); 896 if (err) { 897 pr_warn(DRV_PFX "access denied: DISCARD [%llu->%llu] on dev=%04x\n", 898 preq.sector_number, 899 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice); 900 goto fail_response; 901 } 902 blkif->st_ds_req++; 903 904 secure = (blkif->vbd.discard_secure && 905 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? 906 BLKDEV_DISCARD_SECURE : 0; 907 908 err = blkdev_issue_discard(bdev, req->u.discard.sector_number, 909 req->u.discard.nr_sectors, 910 GFP_KERNEL, secure); 911 fail_response: 912 if (err == -EOPNOTSUPP) { 913 pr_debug(DRV_PFX "discard op failed, not supported\n"); 914 status = BLKIF_RSP_EOPNOTSUPP; 915 } else if (err) 916 status = BLKIF_RSP_ERROR; 917 918 make_response(blkif, req->u.discard.id, req->operation, status); 919 xen_blkif_put(blkif); 920 return err; 921 } 922 923 static int dispatch_other_io(struct xen_blkif *blkif, 924 struct blkif_request *req, 925 struct pending_req *pending_req) 926 { 927 free_req(blkif, pending_req); 928 make_response(blkif, req->u.other.id, req->operation, 929 BLKIF_RSP_EOPNOTSUPP); 930 return -EIO; 931 } 932 933 static void xen_blk_drain_io(struct xen_blkif *blkif) 934 { 935 atomic_set(&blkif->drain, 1); 936 do { 937 /* The initial value is one, and one refcnt taken at the 938 * start of the xen_blkif_schedule thread. */ 939 if (atomic_read(&blkif->refcnt) <= 2) 940 break; 941 wait_for_completion_interruptible_timeout( 942 &blkif->drain_complete, HZ); 943 944 if (!atomic_read(&blkif->drain)) 945 break; 946 } while (!kthread_should_stop()); 947 atomic_set(&blkif->drain, 0); 948 } 949 950 /* 951 * Completion callback on the bio's. Called as bh->b_end_io() 952 */ 953 954 static void __end_block_io_op(struct pending_req *pending_req, int error) 955 { 956 /* An error fails the entire request. */ 957 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && 958 (error == -EOPNOTSUPP)) { 959 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n"); 960 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); 961 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 962 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && 963 (error == -EOPNOTSUPP)) { 964 pr_debug(DRV_PFX "write barrier op failed, not supported\n"); 965 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0); 966 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 967 } else if (error) { 968 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation," 969 " error=%d\n", error); 970 pending_req->status = BLKIF_RSP_ERROR; 971 } 972 973 /* 974 * If all of the bio's have completed it is time to unmap 975 * the grant references associated with 'request' and provide 976 * the proper response on the ring. 977 */ 978 if (atomic_dec_and_test(&pending_req->pendcnt)) { 979 xen_blkbk_unmap(pending_req->blkif, 980 pending_req->segments, 981 pending_req->nr_pages); 982 make_response(pending_req->blkif, pending_req->id, 983 pending_req->operation, pending_req->status); 984 xen_blkif_put(pending_req->blkif); 985 if (atomic_read(&pending_req->blkif->refcnt) <= 2) { 986 if (atomic_read(&pending_req->blkif->drain)) 987 complete(&pending_req->blkif->drain_complete); 988 } 989 free_req(pending_req->blkif, pending_req); 990 } 991 } 992 993 /* 994 * bio callback. 995 */ 996 static void end_block_io_op(struct bio *bio, int error) 997 { 998 __end_block_io_op(bio->bi_private, error); 999 bio_put(bio); 1000 } 1001 1002 1003 1004 /* 1005 * Function to copy the from the ring buffer the 'struct blkif_request' 1006 * (which has the sectors we want, number of them, grant references, etc), 1007 * and transmute it to the block API to hand it over to the proper block disk. 1008 */ 1009 static int 1010 __do_block_io_op(struct xen_blkif *blkif) 1011 { 1012 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1013 struct blkif_request req; 1014 struct pending_req *pending_req; 1015 RING_IDX rc, rp; 1016 int more_to_do = 0; 1017 1018 rc = blk_rings->common.req_cons; 1019 rp = blk_rings->common.sring->req_prod; 1020 rmb(); /* Ensure we see queued requests up to 'rp'. */ 1021 1022 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) { 1023 rc = blk_rings->common.rsp_prod_pvt; 1024 pr_warn(DRV_PFX "Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n", 1025 rp, rc, rp - rc, blkif->vbd.pdevice); 1026 return -EACCES; 1027 } 1028 while (rc != rp) { 1029 1030 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) 1031 break; 1032 1033 if (kthread_should_stop()) { 1034 more_to_do = 1; 1035 break; 1036 } 1037 1038 pending_req = alloc_req(blkif); 1039 if (NULL == pending_req) { 1040 blkif->st_oo_req++; 1041 more_to_do = 1; 1042 break; 1043 } 1044 1045 switch (blkif->blk_protocol) { 1046 case BLKIF_PROTOCOL_NATIVE: 1047 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); 1048 break; 1049 case BLKIF_PROTOCOL_X86_32: 1050 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); 1051 break; 1052 case BLKIF_PROTOCOL_X86_64: 1053 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); 1054 break; 1055 default: 1056 BUG(); 1057 } 1058 blk_rings->common.req_cons = ++rc; /* before make_response() */ 1059 1060 /* Apply all sanity checks to /private copy/ of request. */ 1061 barrier(); 1062 1063 switch (req.operation) { 1064 case BLKIF_OP_READ: 1065 case BLKIF_OP_WRITE: 1066 case BLKIF_OP_WRITE_BARRIER: 1067 case BLKIF_OP_FLUSH_DISKCACHE: 1068 case BLKIF_OP_INDIRECT: 1069 if (dispatch_rw_block_io(blkif, &req, pending_req)) 1070 goto done; 1071 break; 1072 case BLKIF_OP_DISCARD: 1073 free_req(blkif, pending_req); 1074 if (dispatch_discard_io(blkif, &req)) 1075 goto done; 1076 break; 1077 default: 1078 if (dispatch_other_io(blkif, &req, pending_req)) 1079 goto done; 1080 break; 1081 } 1082 1083 /* Yield point for this unbounded loop. */ 1084 cond_resched(); 1085 } 1086 done: 1087 return more_to_do; 1088 } 1089 1090 static int 1091 do_block_io_op(struct xen_blkif *blkif) 1092 { 1093 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1094 int more_to_do; 1095 1096 do { 1097 more_to_do = __do_block_io_op(blkif); 1098 if (more_to_do) 1099 break; 1100 1101 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); 1102 } while (more_to_do); 1103 1104 return more_to_do; 1105 } 1106 /* 1107 * Transmutation of the 'struct blkif_request' to a proper 'struct bio' 1108 * and call the 'submit_bio' to pass it to the underlying storage. 1109 */ 1110 static int dispatch_rw_block_io(struct xen_blkif *blkif, 1111 struct blkif_request *req, 1112 struct pending_req *pending_req) 1113 { 1114 struct phys_req preq; 1115 struct seg_buf *seg = pending_req->seg; 1116 unsigned int nseg; 1117 struct bio *bio = NULL; 1118 struct bio **biolist = pending_req->biolist; 1119 int i, nbio = 0; 1120 int operation; 1121 struct blk_plug plug; 1122 bool drain = false; 1123 struct grant_page **pages = pending_req->segments; 1124 unsigned short req_operation; 1125 1126 req_operation = req->operation == BLKIF_OP_INDIRECT ? 1127 req->u.indirect.indirect_op : req->operation; 1128 if ((req->operation == BLKIF_OP_INDIRECT) && 1129 (req_operation != BLKIF_OP_READ) && 1130 (req_operation != BLKIF_OP_WRITE)) { 1131 pr_debug(DRV_PFX "Invalid indirect operation (%u)\n", 1132 req_operation); 1133 goto fail_response; 1134 } 1135 1136 switch (req_operation) { 1137 case BLKIF_OP_READ: 1138 blkif->st_rd_req++; 1139 operation = READ; 1140 break; 1141 case BLKIF_OP_WRITE: 1142 blkif->st_wr_req++; 1143 operation = WRITE_ODIRECT; 1144 break; 1145 case BLKIF_OP_WRITE_BARRIER: 1146 drain = true; 1147 case BLKIF_OP_FLUSH_DISKCACHE: 1148 blkif->st_f_req++; 1149 operation = WRITE_FLUSH; 1150 break; 1151 default: 1152 operation = 0; /* make gcc happy */ 1153 goto fail_response; 1154 break; 1155 } 1156 1157 /* Check that the number of segments is sane. */ 1158 nseg = req->operation == BLKIF_OP_INDIRECT ? 1159 req->u.indirect.nr_segments : req->u.rw.nr_segments; 1160 1161 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || 1162 unlikely((req->operation != BLKIF_OP_INDIRECT) && 1163 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) || 1164 unlikely((req->operation == BLKIF_OP_INDIRECT) && 1165 (nseg > MAX_INDIRECT_SEGMENTS))) { 1166 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n", 1167 nseg); 1168 /* Haven't submitted any bio's yet. */ 1169 goto fail_response; 1170 } 1171 1172 preq.nr_sects = 0; 1173 1174 pending_req->blkif = blkif; 1175 pending_req->id = req->u.rw.id; 1176 pending_req->operation = req_operation; 1177 pending_req->status = BLKIF_RSP_OKAY; 1178 pending_req->nr_pages = nseg; 1179 1180 if (req->operation != BLKIF_OP_INDIRECT) { 1181 preq.dev = req->u.rw.handle; 1182 preq.sector_number = req->u.rw.sector_number; 1183 for (i = 0; i < nseg; i++) { 1184 pages[i]->gref = req->u.rw.seg[i].gref; 1185 seg[i].nsec = req->u.rw.seg[i].last_sect - 1186 req->u.rw.seg[i].first_sect + 1; 1187 seg[i].offset = (req->u.rw.seg[i].first_sect << 9); 1188 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || 1189 (req->u.rw.seg[i].last_sect < 1190 req->u.rw.seg[i].first_sect)) 1191 goto fail_response; 1192 preq.nr_sects += seg[i].nsec; 1193 } 1194 } else { 1195 preq.dev = req->u.indirect.handle; 1196 preq.sector_number = req->u.indirect.sector_number; 1197 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq)) 1198 goto fail_response; 1199 } 1200 1201 if (xen_vbd_translate(&preq, blkif, operation) != 0) { 1202 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n", 1203 operation == READ ? "read" : "write", 1204 preq.sector_number, 1205 preq.sector_number + preq.nr_sects, 1206 blkif->vbd.pdevice); 1207 goto fail_response; 1208 } 1209 1210 /* 1211 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev 1212 * is set there. 1213 */ 1214 for (i = 0; i < nseg; i++) { 1215 if (((int)preq.sector_number|(int)seg[i].nsec) & 1216 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { 1217 pr_debug(DRV_PFX "Misaligned I/O request from domain %d", 1218 blkif->domid); 1219 goto fail_response; 1220 } 1221 } 1222 1223 /* Wait on all outstanding I/O's and once that has been completed 1224 * issue the WRITE_FLUSH. 1225 */ 1226 if (drain) 1227 xen_blk_drain_io(pending_req->blkif); 1228 1229 /* 1230 * If we have failed at this point, we need to undo the M2P override, 1231 * set gnttab_set_unmap_op on all of the grant references and perform 1232 * the hypercall to unmap the grants - that is all done in 1233 * xen_blkbk_unmap. 1234 */ 1235 if (xen_blkbk_map_seg(pending_req)) 1236 goto fail_flush; 1237 1238 /* 1239 * This corresponding xen_blkif_put is done in __end_block_io_op, or 1240 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. 1241 */ 1242 xen_blkif_get(blkif); 1243 1244 for (i = 0; i < nseg; i++) { 1245 while ((bio == NULL) || 1246 (bio_add_page(bio, 1247 pages[i]->page, 1248 seg[i].nsec << 9, 1249 seg[i].offset) == 0)) { 1250 1251 int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES); 1252 bio = bio_alloc(GFP_KERNEL, nr_iovecs); 1253 if (unlikely(bio == NULL)) 1254 goto fail_put_bio; 1255 1256 biolist[nbio++] = bio; 1257 bio->bi_bdev = preq.bdev; 1258 bio->bi_private = pending_req; 1259 bio->bi_end_io = end_block_io_op; 1260 bio->bi_sector = preq.sector_number; 1261 } 1262 1263 preq.sector_number += seg[i].nsec; 1264 } 1265 1266 /* This will be hit if the operation was a flush or discard. */ 1267 if (!bio) { 1268 BUG_ON(operation != WRITE_FLUSH); 1269 1270 bio = bio_alloc(GFP_KERNEL, 0); 1271 if (unlikely(bio == NULL)) 1272 goto fail_put_bio; 1273 1274 biolist[nbio++] = bio; 1275 bio->bi_bdev = preq.bdev; 1276 bio->bi_private = pending_req; 1277 bio->bi_end_io = end_block_io_op; 1278 } 1279 1280 atomic_set(&pending_req->pendcnt, nbio); 1281 blk_start_plug(&plug); 1282 1283 for (i = 0; i < nbio; i++) 1284 submit_bio(operation, biolist[i]); 1285 1286 /* Let the I/Os go.. */ 1287 blk_finish_plug(&plug); 1288 1289 if (operation == READ) 1290 blkif->st_rd_sect += preq.nr_sects; 1291 else if (operation & WRITE) 1292 blkif->st_wr_sect += preq.nr_sects; 1293 1294 return 0; 1295 1296 fail_flush: 1297 xen_blkbk_unmap(blkif, pending_req->segments, 1298 pending_req->nr_pages); 1299 fail_response: 1300 /* Haven't submitted any bio's yet. */ 1301 make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR); 1302 free_req(blkif, pending_req); 1303 msleep(1); /* back off a bit */ 1304 return -EIO; 1305 1306 fail_put_bio: 1307 for (i = 0; i < nbio; i++) 1308 bio_put(biolist[i]); 1309 atomic_set(&pending_req->pendcnt, 1); 1310 __end_block_io_op(pending_req, -EINVAL); 1311 msleep(1); /* back off a bit */ 1312 return -EIO; 1313 } 1314 1315 1316 1317 /* 1318 * Put a response on the ring on how the operation fared. 1319 */ 1320 static void make_response(struct xen_blkif *blkif, u64 id, 1321 unsigned short op, int st) 1322 { 1323 struct blkif_response resp; 1324 unsigned long flags; 1325 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1326 int notify; 1327 1328 resp.id = id; 1329 resp.operation = op; 1330 resp.status = st; 1331 1332 spin_lock_irqsave(&blkif->blk_ring_lock, flags); 1333 /* Place on the response ring for the relevant domain. */ 1334 switch (blkif->blk_protocol) { 1335 case BLKIF_PROTOCOL_NATIVE: 1336 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), 1337 &resp, sizeof(resp)); 1338 break; 1339 case BLKIF_PROTOCOL_X86_32: 1340 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), 1341 &resp, sizeof(resp)); 1342 break; 1343 case BLKIF_PROTOCOL_X86_64: 1344 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), 1345 &resp, sizeof(resp)); 1346 break; 1347 default: 1348 BUG(); 1349 } 1350 blk_rings->common.rsp_prod_pvt++; 1351 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); 1352 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); 1353 if (notify) 1354 notify_remote_via_irq(blkif->irq); 1355 } 1356 1357 static int __init xen_blkif_init(void) 1358 { 1359 int rc = 0; 1360 1361 if (!xen_domain()) 1362 return -ENODEV; 1363 1364 rc = xen_blkif_interface_init(); 1365 if (rc) 1366 goto failed_init; 1367 1368 rc = xen_blkif_xenbus_init(); 1369 if (rc) 1370 goto failed_init; 1371 1372 failed_init: 1373 return rc; 1374 } 1375 1376 module_init(xen_blkif_init); 1377 1378 MODULE_LICENSE("Dual BSD/GPL"); 1379 MODULE_ALIAS("xen-backend:vbd"); 1380