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, pages, segs_to_unmap); 289 BUG_ON(ret); 290 put_free_pages(blkif, pages, segs_to_unmap); 291 segs_to_unmap = 0; 292 } 293 294 rb_erase(&persistent_gnt->node, root); 295 kfree(persistent_gnt); 296 num--; 297 } 298 BUG_ON(num != 0); 299 } 300 301 static void unmap_purged_grants(struct work_struct *work) 302 { 303 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 304 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 305 struct persistent_gnt *persistent_gnt; 306 int ret, segs_to_unmap = 0; 307 struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work); 308 309 while(!list_empty(&blkif->persistent_purge_list)) { 310 persistent_gnt = list_first_entry(&blkif->persistent_purge_list, 311 struct persistent_gnt, 312 remove_node); 313 list_del(&persistent_gnt->remove_node); 314 315 gnttab_set_unmap_op(&unmap[segs_to_unmap], 316 vaddr(persistent_gnt->page), 317 GNTMAP_host_map, 318 persistent_gnt->handle); 319 320 pages[segs_to_unmap] = persistent_gnt->page; 321 322 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) { 323 ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap); 324 BUG_ON(ret); 325 put_free_pages(blkif, pages, segs_to_unmap); 326 segs_to_unmap = 0; 327 } 328 kfree(persistent_gnt); 329 } 330 if (segs_to_unmap > 0) { 331 ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap); 332 BUG_ON(ret); 333 put_free_pages(blkif, pages, segs_to_unmap); 334 } 335 } 336 337 static void purge_persistent_gnt(struct xen_blkif *blkif) 338 { 339 struct persistent_gnt *persistent_gnt; 340 struct rb_node *n; 341 unsigned int num_clean, total; 342 bool scan_used = false, clean_used = false; 343 struct rb_root *root; 344 345 if (blkif->persistent_gnt_c < xen_blkif_max_pgrants || 346 (blkif->persistent_gnt_c == xen_blkif_max_pgrants && 347 !blkif->vbd.overflow_max_grants)) { 348 return; 349 } 350 351 if (work_pending(&blkif->persistent_purge_work)) { 352 pr_alert_ratelimited(DRV_PFX "Scheduled work from previous purge is still pending, cannot purge list\n"); 353 return; 354 } 355 356 num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN; 357 num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean; 358 num_clean = min(blkif->persistent_gnt_c, num_clean); 359 if ((num_clean == 0) || 360 (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use)))) 361 return; 362 363 /* 364 * At this point, we can assure that there will be no calls 365 * to get_persistent_grant (because we are executing this code from 366 * xen_blkif_schedule), there can only be calls to put_persistent_gnt, 367 * which means that the number of currently used grants will go down, 368 * but never up, so we will always be able to remove the requested 369 * number of grants. 370 */ 371 372 total = num_clean; 373 374 pr_debug(DRV_PFX "Going to purge %u persistent grants\n", num_clean); 375 376 INIT_LIST_HEAD(&blkif->persistent_purge_list); 377 root = &blkif->persistent_gnts; 378 purge_list: 379 foreach_grant_safe(persistent_gnt, n, root, node) { 380 BUG_ON(persistent_gnt->handle == 381 BLKBACK_INVALID_HANDLE); 382 383 if (clean_used) { 384 clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags); 385 continue; 386 } 387 388 if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags)) 389 continue; 390 if (!scan_used && 391 (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags))) 392 continue; 393 394 rb_erase(&persistent_gnt->node, root); 395 list_add(&persistent_gnt->remove_node, 396 &blkif->persistent_purge_list); 397 if (--num_clean == 0) 398 goto finished; 399 } 400 /* 401 * If we get here it means we also need to start cleaning 402 * grants that were used since last purge in order to cope 403 * with the requested num 404 */ 405 if (!scan_used && !clean_used) { 406 pr_debug(DRV_PFX "Still missing %u purged frames\n", num_clean); 407 scan_used = true; 408 goto purge_list; 409 } 410 finished: 411 if (!clean_used) { 412 pr_debug(DRV_PFX "Finished scanning for grants to clean, removing used flag\n"); 413 clean_used = true; 414 goto purge_list; 415 } 416 417 blkif->persistent_gnt_c -= (total - num_clean); 418 blkif->vbd.overflow_max_grants = 0; 419 420 /* We can defer this work */ 421 INIT_WORK(&blkif->persistent_purge_work, unmap_purged_grants); 422 schedule_work(&blkif->persistent_purge_work); 423 pr_debug(DRV_PFX "Purged %u/%u\n", (total - num_clean), total); 424 return; 425 } 426 427 /* 428 * Retrieve from the 'pending_reqs' a free pending_req structure to be used. 429 */ 430 static struct pending_req *alloc_req(struct xen_blkif *blkif) 431 { 432 struct pending_req *req = NULL; 433 unsigned long flags; 434 435 spin_lock_irqsave(&blkif->pending_free_lock, flags); 436 if (!list_empty(&blkif->pending_free)) { 437 req = list_entry(blkif->pending_free.next, struct pending_req, 438 free_list); 439 list_del(&req->free_list); 440 } 441 spin_unlock_irqrestore(&blkif->pending_free_lock, flags); 442 return req; 443 } 444 445 /* 446 * Return the 'pending_req' structure back to the freepool. We also 447 * wake up the thread if it was waiting for a free page. 448 */ 449 static void free_req(struct xen_blkif *blkif, struct pending_req *req) 450 { 451 unsigned long flags; 452 int was_empty; 453 454 spin_lock_irqsave(&blkif->pending_free_lock, flags); 455 was_empty = list_empty(&blkif->pending_free); 456 list_add(&req->free_list, &blkif->pending_free); 457 spin_unlock_irqrestore(&blkif->pending_free_lock, flags); 458 if (was_empty) 459 wake_up(&blkif->pending_free_wq); 460 } 461 462 /* 463 * Routines for managing virtual block devices (vbds). 464 */ 465 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, 466 int operation) 467 { 468 struct xen_vbd *vbd = &blkif->vbd; 469 int rc = -EACCES; 470 471 if ((operation != READ) && vbd->readonly) 472 goto out; 473 474 if (likely(req->nr_sects)) { 475 blkif_sector_t end = req->sector_number + req->nr_sects; 476 477 if (unlikely(end < req->sector_number)) 478 goto out; 479 if (unlikely(end > vbd_sz(vbd))) 480 goto out; 481 } 482 483 req->dev = vbd->pdevice; 484 req->bdev = vbd->bdev; 485 rc = 0; 486 487 out: 488 return rc; 489 } 490 491 static void xen_vbd_resize(struct xen_blkif *blkif) 492 { 493 struct xen_vbd *vbd = &blkif->vbd; 494 struct xenbus_transaction xbt; 495 int err; 496 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); 497 unsigned long long new_size = vbd_sz(vbd); 498 499 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n", 500 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); 501 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size); 502 vbd->size = new_size; 503 again: 504 err = xenbus_transaction_start(&xbt); 505 if (err) { 506 pr_warn(DRV_PFX "Error starting transaction"); 507 return; 508 } 509 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 510 (unsigned long long)vbd_sz(vbd)); 511 if (err) { 512 pr_warn(DRV_PFX "Error writing new size"); 513 goto abort; 514 } 515 /* 516 * Write the current state; we will use this to synchronize 517 * the front-end. If the current state is "connected" the 518 * front-end will get the new size information online. 519 */ 520 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); 521 if (err) { 522 pr_warn(DRV_PFX "Error writing the state"); 523 goto abort; 524 } 525 526 err = xenbus_transaction_end(xbt, 0); 527 if (err == -EAGAIN) 528 goto again; 529 if (err) 530 pr_warn(DRV_PFX "Error ending transaction"); 531 return; 532 abort: 533 xenbus_transaction_end(xbt, 1); 534 } 535 536 /* 537 * Notification from the guest OS. 538 */ 539 static void blkif_notify_work(struct xen_blkif *blkif) 540 { 541 blkif->waiting_reqs = 1; 542 wake_up(&blkif->wq); 543 } 544 545 irqreturn_t xen_blkif_be_int(int irq, void *dev_id) 546 { 547 blkif_notify_work(dev_id); 548 return IRQ_HANDLED; 549 } 550 551 /* 552 * SCHEDULER FUNCTIONS 553 */ 554 555 static void print_stats(struct xen_blkif *blkif) 556 { 557 pr_info("xen-blkback (%s): oo %3llu | rd %4llu | wr %4llu | f %4llu" 558 " | ds %4llu | pg: %4u/%4d\n", 559 current->comm, blkif->st_oo_req, 560 blkif->st_rd_req, blkif->st_wr_req, 561 blkif->st_f_req, blkif->st_ds_req, 562 blkif->persistent_gnt_c, 563 xen_blkif_max_pgrants); 564 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); 565 blkif->st_rd_req = 0; 566 blkif->st_wr_req = 0; 567 blkif->st_oo_req = 0; 568 blkif->st_ds_req = 0; 569 } 570 571 int xen_blkif_schedule(void *arg) 572 { 573 struct xen_blkif *blkif = arg; 574 struct xen_vbd *vbd = &blkif->vbd; 575 unsigned long timeout; 576 int ret; 577 578 xen_blkif_get(blkif); 579 580 while (!kthread_should_stop()) { 581 if (try_to_freeze()) 582 continue; 583 if (unlikely(vbd->size != vbd_sz(vbd))) 584 xen_vbd_resize(blkif); 585 586 timeout = msecs_to_jiffies(LRU_INTERVAL); 587 588 timeout = wait_event_interruptible_timeout( 589 blkif->wq, 590 blkif->waiting_reqs || kthread_should_stop(), 591 timeout); 592 if (timeout == 0) 593 goto purge_gnt_list; 594 timeout = wait_event_interruptible_timeout( 595 blkif->pending_free_wq, 596 !list_empty(&blkif->pending_free) || 597 kthread_should_stop(), 598 timeout); 599 if (timeout == 0) 600 goto purge_gnt_list; 601 602 blkif->waiting_reqs = 0; 603 smp_mb(); /* clear flag *before* checking for work */ 604 605 ret = do_block_io_op(blkif); 606 if (ret > 0) 607 blkif->waiting_reqs = 1; 608 if (ret == -EACCES) 609 wait_event_interruptible(blkif->shutdown_wq, 610 kthread_should_stop()); 611 612 purge_gnt_list: 613 if (blkif->vbd.feature_gnt_persistent && 614 time_after(jiffies, blkif->next_lru)) { 615 purge_persistent_gnt(blkif); 616 blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL); 617 } 618 619 /* Shrink if we have more than xen_blkif_max_buffer_pages */ 620 shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages); 621 622 if (log_stats && time_after(jiffies, blkif->st_print)) 623 print_stats(blkif); 624 } 625 626 /* Since we are shutting down remove all pages from the buffer */ 627 shrink_free_pagepool(blkif, 0 /* All */); 628 629 /* Free all persistent grant pages */ 630 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts)) 631 free_persistent_gnts(blkif, &blkif->persistent_gnts, 632 blkif->persistent_gnt_c); 633 634 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); 635 blkif->persistent_gnt_c = 0; 636 637 if (log_stats) 638 print_stats(blkif); 639 640 blkif->xenblkd = NULL; 641 xen_blkif_put(blkif); 642 643 return 0; 644 } 645 646 /* 647 * Unmap the grant references, and also remove the M2P over-rides 648 * used in the 'pending_req'. 649 */ 650 static void xen_blkbk_unmap(struct xen_blkif *blkif, 651 struct grant_page *pages[], 652 int num) 653 { 654 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 655 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 656 unsigned int i, invcount = 0; 657 int ret; 658 659 for (i = 0; i < num; i++) { 660 if (pages[i]->persistent_gnt != NULL) { 661 put_persistent_gnt(blkif, pages[i]->persistent_gnt); 662 continue; 663 } 664 if (pages[i]->handle == BLKBACK_INVALID_HANDLE) 665 continue; 666 unmap_pages[invcount] = pages[i]->page; 667 gnttab_set_unmap_op(&unmap[invcount], vaddr(pages[i]->page), 668 GNTMAP_host_map, pages[i]->handle); 669 pages[i]->handle = BLKBACK_INVALID_HANDLE; 670 if (++invcount == BLKIF_MAX_SEGMENTS_PER_REQUEST) { 671 ret = gnttab_unmap_refs(unmap, unmap_pages, invcount); 672 BUG_ON(ret); 673 put_free_pages(blkif, unmap_pages, invcount); 674 invcount = 0; 675 } 676 } 677 if (invcount) { 678 ret = gnttab_unmap_refs(unmap, unmap_pages, invcount); 679 BUG_ON(ret); 680 put_free_pages(blkif, unmap_pages, invcount); 681 } 682 } 683 684 static int xen_blkbk_map(struct xen_blkif *blkif, 685 struct grant_page *pages[], 686 int num, bool ro) 687 { 688 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 689 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 690 struct persistent_gnt *persistent_gnt = NULL; 691 phys_addr_t addr = 0; 692 int i, seg_idx, new_map_idx; 693 int segs_to_map = 0; 694 int ret = 0; 695 int last_map = 0, map_until = 0; 696 int use_persistent_gnts; 697 698 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent); 699 700 /* 701 * Fill out preq.nr_sects with proper amount of sectors, and setup 702 * assign map[..] with the PFN of the page in our domain with the 703 * corresponding grant reference for each page. 704 */ 705 again: 706 for (i = map_until; i < num; i++) { 707 uint32_t flags; 708 709 if (use_persistent_gnts) 710 persistent_gnt = get_persistent_gnt( 711 blkif, 712 pages[i]->gref); 713 714 if (persistent_gnt) { 715 /* 716 * We are using persistent grants and 717 * the grant is already mapped 718 */ 719 pages[i]->page = persistent_gnt->page; 720 pages[i]->persistent_gnt = persistent_gnt; 721 } else { 722 if (get_free_page(blkif, &pages[i]->page)) 723 goto out_of_memory; 724 addr = vaddr(pages[i]->page); 725 pages_to_gnt[segs_to_map] = pages[i]->page; 726 pages[i]->persistent_gnt = NULL; 727 flags = GNTMAP_host_map; 728 if (!use_persistent_gnts && ro) 729 flags |= GNTMAP_readonly; 730 gnttab_set_map_op(&map[segs_to_map++], addr, 731 flags, pages[i]->gref, 732 blkif->domid); 733 } 734 map_until = i + 1; 735 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST) 736 break; 737 } 738 739 if (segs_to_map) { 740 ret = gnttab_map_refs(map, pages_to_gnt, segs_to_map); 741 BUG_ON(ret); 742 } 743 744 /* 745 * Now swizzle the MFN in our domain with the MFN from the other domain 746 * so that when we access vaddr(pending_req,i) it has the contents of 747 * the page from the other domain. 748 */ 749 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) { 750 if (!pages[seg_idx]->persistent_gnt) { 751 /* This is a newly mapped grant */ 752 BUG_ON(new_map_idx >= segs_to_map); 753 if (unlikely(map[new_map_idx].status != 0)) { 754 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n"); 755 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE; 756 ret |= 1; 757 goto next; 758 } 759 pages[seg_idx]->handle = map[new_map_idx].handle; 760 } else { 761 continue; 762 } 763 if (use_persistent_gnts && 764 blkif->persistent_gnt_c < xen_blkif_max_pgrants) { 765 /* 766 * We are using persistent grants, the grant is 767 * not mapped but we might have room for it. 768 */ 769 persistent_gnt = kmalloc(sizeof(struct persistent_gnt), 770 GFP_KERNEL); 771 if (!persistent_gnt) { 772 /* 773 * If we don't have enough memory to 774 * allocate the persistent_gnt struct 775 * map this grant non-persistenly 776 */ 777 goto next; 778 } 779 persistent_gnt->gnt = map[new_map_idx].ref; 780 persistent_gnt->handle = map[new_map_idx].handle; 781 persistent_gnt->page = pages[seg_idx]->page; 782 if (add_persistent_gnt(blkif, 783 persistent_gnt)) { 784 kfree(persistent_gnt); 785 persistent_gnt = NULL; 786 goto next; 787 } 788 pages[seg_idx]->persistent_gnt = persistent_gnt; 789 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n", 790 persistent_gnt->gnt, blkif->persistent_gnt_c, 791 xen_blkif_max_pgrants); 792 goto next; 793 } 794 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) { 795 blkif->vbd.overflow_max_grants = 1; 796 pr_debug(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n", 797 blkif->domid, blkif->vbd.handle); 798 } 799 /* 800 * We could not map this grant persistently, so use it as 801 * a non-persistent grant. 802 */ 803 next: 804 new_map_idx++; 805 } 806 segs_to_map = 0; 807 last_map = map_until; 808 if (map_until != num) 809 goto again; 810 811 return ret; 812 813 out_of_memory: 814 pr_alert(DRV_PFX "%s: out of memory\n", __func__); 815 put_free_pages(blkif, pages_to_gnt, segs_to_map); 816 return -ENOMEM; 817 } 818 819 static int xen_blkbk_map_seg(struct pending_req *pending_req) 820 { 821 int rc; 822 823 rc = xen_blkbk_map(pending_req->blkif, pending_req->segments, 824 pending_req->nr_pages, 825 (pending_req->operation != BLKIF_OP_READ)); 826 827 return rc; 828 } 829 830 static int xen_blkbk_parse_indirect(struct blkif_request *req, 831 struct pending_req *pending_req, 832 struct seg_buf seg[], 833 struct phys_req *preq) 834 { 835 struct grant_page **pages = pending_req->indirect_pages; 836 struct xen_blkif *blkif = pending_req->blkif; 837 int indirect_grefs, rc, n, nseg, i; 838 struct blkif_request_segment_aligned *segments = NULL; 839 840 nseg = pending_req->nr_pages; 841 indirect_grefs = INDIRECT_PAGES(nseg); 842 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); 843 844 for (i = 0; i < indirect_grefs; i++) 845 pages[i]->gref = req->u.indirect.indirect_grefs[i]; 846 847 rc = xen_blkbk_map(blkif, pages, indirect_grefs, true); 848 if (rc) 849 goto unmap; 850 851 for (n = 0, i = 0; n < nseg; n++) { 852 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) { 853 /* Map indirect segments */ 854 if (segments) 855 kunmap_atomic(segments); 856 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page); 857 } 858 i = n % SEGS_PER_INDIRECT_FRAME; 859 pending_req->segments[n]->gref = segments[i].gref; 860 seg[n].nsec = segments[i].last_sect - 861 segments[i].first_sect + 1; 862 seg[n].offset = (segments[i].first_sect << 9); 863 if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) || 864 (segments[i].last_sect < segments[i].first_sect)) { 865 rc = -EINVAL; 866 goto unmap; 867 } 868 preq->nr_sects += seg[n].nsec; 869 } 870 871 unmap: 872 if (segments) 873 kunmap_atomic(segments); 874 xen_blkbk_unmap(blkif, pages, indirect_grefs); 875 return rc; 876 } 877 878 static int dispatch_discard_io(struct xen_blkif *blkif, 879 struct blkif_request *req) 880 { 881 int err = 0; 882 int status = BLKIF_RSP_OKAY; 883 struct block_device *bdev = blkif->vbd.bdev; 884 unsigned long secure; 885 struct phys_req preq; 886 887 xen_blkif_get(blkif); 888 889 preq.sector_number = req->u.discard.sector_number; 890 preq.nr_sects = req->u.discard.nr_sectors; 891 892 err = xen_vbd_translate(&preq, blkif, WRITE); 893 if (err) { 894 pr_warn(DRV_PFX "access denied: DISCARD [%llu->%llu] on dev=%04x\n", 895 preq.sector_number, 896 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice); 897 goto fail_response; 898 } 899 blkif->st_ds_req++; 900 901 secure = (blkif->vbd.discard_secure && 902 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? 903 BLKDEV_DISCARD_SECURE : 0; 904 905 err = blkdev_issue_discard(bdev, req->u.discard.sector_number, 906 req->u.discard.nr_sectors, 907 GFP_KERNEL, secure); 908 fail_response: 909 if (err == -EOPNOTSUPP) { 910 pr_debug(DRV_PFX "discard op failed, not supported\n"); 911 status = BLKIF_RSP_EOPNOTSUPP; 912 } else if (err) 913 status = BLKIF_RSP_ERROR; 914 915 make_response(blkif, req->u.discard.id, req->operation, status); 916 xen_blkif_put(blkif); 917 return err; 918 } 919 920 static int dispatch_other_io(struct xen_blkif *blkif, 921 struct blkif_request *req, 922 struct pending_req *pending_req) 923 { 924 free_req(blkif, pending_req); 925 make_response(blkif, req->u.other.id, req->operation, 926 BLKIF_RSP_EOPNOTSUPP); 927 return -EIO; 928 } 929 930 static void xen_blk_drain_io(struct xen_blkif *blkif) 931 { 932 atomic_set(&blkif->drain, 1); 933 do { 934 /* The initial value is one, and one refcnt taken at the 935 * start of the xen_blkif_schedule thread. */ 936 if (atomic_read(&blkif->refcnt) <= 2) 937 break; 938 wait_for_completion_interruptible_timeout( 939 &blkif->drain_complete, HZ); 940 941 if (!atomic_read(&blkif->drain)) 942 break; 943 } while (!kthread_should_stop()); 944 atomic_set(&blkif->drain, 0); 945 } 946 947 /* 948 * Completion callback on the bio's. Called as bh->b_end_io() 949 */ 950 951 static void __end_block_io_op(struct pending_req *pending_req, int error) 952 { 953 /* An error fails the entire request. */ 954 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && 955 (error == -EOPNOTSUPP)) { 956 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n"); 957 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); 958 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 959 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && 960 (error == -EOPNOTSUPP)) { 961 pr_debug(DRV_PFX "write barrier op failed, not supported\n"); 962 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0); 963 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 964 } else if (error) { 965 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation," 966 " error=%d\n", error); 967 pending_req->status = BLKIF_RSP_ERROR; 968 } 969 970 /* 971 * If all of the bio's have completed it is time to unmap 972 * the grant references associated with 'request' and provide 973 * the proper response on the ring. 974 */ 975 if (atomic_dec_and_test(&pending_req->pendcnt)) { 976 xen_blkbk_unmap(pending_req->blkif, 977 pending_req->segments, 978 pending_req->nr_pages); 979 make_response(pending_req->blkif, pending_req->id, 980 pending_req->operation, pending_req->status); 981 xen_blkif_put(pending_req->blkif); 982 if (atomic_read(&pending_req->blkif->refcnt) <= 2) { 983 if (atomic_read(&pending_req->blkif->drain)) 984 complete(&pending_req->blkif->drain_complete); 985 } 986 free_req(pending_req->blkif, pending_req); 987 } 988 } 989 990 /* 991 * bio callback. 992 */ 993 static void end_block_io_op(struct bio *bio, int error) 994 { 995 __end_block_io_op(bio->bi_private, error); 996 bio_put(bio); 997 } 998 999 1000 1001 /* 1002 * Function to copy the from the ring buffer the 'struct blkif_request' 1003 * (which has the sectors we want, number of them, grant references, etc), 1004 * and transmute it to the block API to hand it over to the proper block disk. 1005 */ 1006 static int 1007 __do_block_io_op(struct xen_blkif *blkif) 1008 { 1009 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1010 struct blkif_request req; 1011 struct pending_req *pending_req; 1012 RING_IDX rc, rp; 1013 int more_to_do = 0; 1014 1015 rc = blk_rings->common.req_cons; 1016 rp = blk_rings->common.sring->req_prod; 1017 rmb(); /* Ensure we see queued requests up to 'rp'. */ 1018 1019 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) { 1020 rc = blk_rings->common.rsp_prod_pvt; 1021 pr_warn(DRV_PFX "Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n", 1022 rp, rc, rp - rc, blkif->vbd.pdevice); 1023 return -EACCES; 1024 } 1025 while (rc != rp) { 1026 1027 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) 1028 break; 1029 1030 if (kthread_should_stop()) { 1031 more_to_do = 1; 1032 break; 1033 } 1034 1035 pending_req = alloc_req(blkif); 1036 if (NULL == pending_req) { 1037 blkif->st_oo_req++; 1038 more_to_do = 1; 1039 break; 1040 } 1041 1042 switch (blkif->blk_protocol) { 1043 case BLKIF_PROTOCOL_NATIVE: 1044 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); 1045 break; 1046 case BLKIF_PROTOCOL_X86_32: 1047 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); 1048 break; 1049 case BLKIF_PROTOCOL_X86_64: 1050 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); 1051 break; 1052 default: 1053 BUG(); 1054 } 1055 blk_rings->common.req_cons = ++rc; /* before make_response() */ 1056 1057 /* Apply all sanity checks to /private copy/ of request. */ 1058 barrier(); 1059 1060 switch (req.operation) { 1061 case BLKIF_OP_READ: 1062 case BLKIF_OP_WRITE: 1063 case BLKIF_OP_WRITE_BARRIER: 1064 case BLKIF_OP_FLUSH_DISKCACHE: 1065 case BLKIF_OP_INDIRECT: 1066 if (dispatch_rw_block_io(blkif, &req, pending_req)) 1067 goto done; 1068 break; 1069 case BLKIF_OP_DISCARD: 1070 free_req(blkif, pending_req); 1071 if (dispatch_discard_io(blkif, &req)) 1072 goto done; 1073 break; 1074 default: 1075 if (dispatch_other_io(blkif, &req, pending_req)) 1076 goto done; 1077 break; 1078 } 1079 1080 /* Yield point for this unbounded loop. */ 1081 cond_resched(); 1082 } 1083 done: 1084 return more_to_do; 1085 } 1086 1087 static int 1088 do_block_io_op(struct xen_blkif *blkif) 1089 { 1090 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1091 int more_to_do; 1092 1093 do { 1094 more_to_do = __do_block_io_op(blkif); 1095 if (more_to_do) 1096 break; 1097 1098 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); 1099 } while (more_to_do); 1100 1101 return more_to_do; 1102 } 1103 /* 1104 * Transmutation of the 'struct blkif_request' to a proper 'struct bio' 1105 * and call the 'submit_bio' to pass it to the underlying storage. 1106 */ 1107 static int dispatch_rw_block_io(struct xen_blkif *blkif, 1108 struct blkif_request *req, 1109 struct pending_req *pending_req) 1110 { 1111 struct phys_req preq; 1112 struct seg_buf *seg = pending_req->seg; 1113 unsigned int nseg; 1114 struct bio *bio = NULL; 1115 struct bio **biolist = pending_req->biolist; 1116 int i, nbio = 0; 1117 int operation; 1118 struct blk_plug plug; 1119 bool drain = false; 1120 struct grant_page **pages = pending_req->segments; 1121 unsigned short req_operation; 1122 1123 req_operation = req->operation == BLKIF_OP_INDIRECT ? 1124 req->u.indirect.indirect_op : req->operation; 1125 if ((req->operation == BLKIF_OP_INDIRECT) && 1126 (req_operation != BLKIF_OP_READ) && 1127 (req_operation != BLKIF_OP_WRITE)) { 1128 pr_debug(DRV_PFX "Invalid indirect operation (%u)\n", 1129 req_operation); 1130 goto fail_response; 1131 } 1132 1133 switch (req_operation) { 1134 case BLKIF_OP_READ: 1135 blkif->st_rd_req++; 1136 operation = READ; 1137 break; 1138 case BLKIF_OP_WRITE: 1139 blkif->st_wr_req++; 1140 operation = WRITE_ODIRECT; 1141 break; 1142 case BLKIF_OP_WRITE_BARRIER: 1143 drain = true; 1144 case BLKIF_OP_FLUSH_DISKCACHE: 1145 blkif->st_f_req++; 1146 operation = WRITE_FLUSH; 1147 break; 1148 default: 1149 operation = 0; /* make gcc happy */ 1150 goto fail_response; 1151 break; 1152 } 1153 1154 /* Check that the number of segments is sane. */ 1155 nseg = req->operation == BLKIF_OP_INDIRECT ? 1156 req->u.indirect.nr_segments : req->u.rw.nr_segments; 1157 1158 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || 1159 unlikely((req->operation != BLKIF_OP_INDIRECT) && 1160 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) || 1161 unlikely((req->operation == BLKIF_OP_INDIRECT) && 1162 (nseg > MAX_INDIRECT_SEGMENTS))) { 1163 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n", 1164 nseg); 1165 /* Haven't submitted any bio's yet. */ 1166 goto fail_response; 1167 } 1168 1169 preq.nr_sects = 0; 1170 1171 pending_req->blkif = blkif; 1172 pending_req->id = req->u.rw.id; 1173 pending_req->operation = req_operation; 1174 pending_req->status = BLKIF_RSP_OKAY; 1175 pending_req->nr_pages = nseg; 1176 1177 if (req->operation != BLKIF_OP_INDIRECT) { 1178 preq.dev = req->u.rw.handle; 1179 preq.sector_number = req->u.rw.sector_number; 1180 for (i = 0; i < nseg; i++) { 1181 pages[i]->gref = req->u.rw.seg[i].gref; 1182 seg[i].nsec = req->u.rw.seg[i].last_sect - 1183 req->u.rw.seg[i].first_sect + 1; 1184 seg[i].offset = (req->u.rw.seg[i].first_sect << 9); 1185 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || 1186 (req->u.rw.seg[i].last_sect < 1187 req->u.rw.seg[i].first_sect)) 1188 goto fail_response; 1189 preq.nr_sects += seg[i].nsec; 1190 } 1191 } else { 1192 preq.dev = req->u.indirect.handle; 1193 preq.sector_number = req->u.indirect.sector_number; 1194 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq)) 1195 goto fail_response; 1196 } 1197 1198 if (xen_vbd_translate(&preq, blkif, operation) != 0) { 1199 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n", 1200 operation == READ ? "read" : "write", 1201 preq.sector_number, 1202 preq.sector_number + preq.nr_sects, 1203 blkif->vbd.pdevice); 1204 goto fail_response; 1205 } 1206 1207 /* 1208 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev 1209 * is set there. 1210 */ 1211 for (i = 0; i < nseg; i++) { 1212 if (((int)preq.sector_number|(int)seg[i].nsec) & 1213 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { 1214 pr_debug(DRV_PFX "Misaligned I/O request from domain %d", 1215 blkif->domid); 1216 goto fail_response; 1217 } 1218 } 1219 1220 /* Wait on all outstanding I/O's and once that has been completed 1221 * issue the WRITE_FLUSH. 1222 */ 1223 if (drain) 1224 xen_blk_drain_io(pending_req->blkif); 1225 1226 /* 1227 * If we have failed at this point, we need to undo the M2P override, 1228 * set gnttab_set_unmap_op on all of the grant references and perform 1229 * the hypercall to unmap the grants - that is all done in 1230 * xen_blkbk_unmap. 1231 */ 1232 if (xen_blkbk_map_seg(pending_req)) 1233 goto fail_flush; 1234 1235 /* 1236 * This corresponding xen_blkif_put is done in __end_block_io_op, or 1237 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. 1238 */ 1239 xen_blkif_get(blkif); 1240 1241 for (i = 0; i < nseg; i++) { 1242 while ((bio == NULL) || 1243 (bio_add_page(bio, 1244 pages[i]->page, 1245 seg[i].nsec << 9, 1246 seg[i].offset) == 0)) { 1247 1248 int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES); 1249 bio = bio_alloc(GFP_KERNEL, nr_iovecs); 1250 if (unlikely(bio == NULL)) 1251 goto fail_put_bio; 1252 1253 biolist[nbio++] = bio; 1254 bio->bi_bdev = preq.bdev; 1255 bio->bi_private = pending_req; 1256 bio->bi_end_io = end_block_io_op; 1257 bio->bi_iter.bi_sector = preq.sector_number; 1258 } 1259 1260 preq.sector_number += seg[i].nsec; 1261 } 1262 1263 /* This will be hit if the operation was a flush or discard. */ 1264 if (!bio) { 1265 BUG_ON(operation != WRITE_FLUSH); 1266 1267 bio = bio_alloc(GFP_KERNEL, 0); 1268 if (unlikely(bio == NULL)) 1269 goto fail_put_bio; 1270 1271 biolist[nbio++] = bio; 1272 bio->bi_bdev = preq.bdev; 1273 bio->bi_private = pending_req; 1274 bio->bi_end_io = end_block_io_op; 1275 } 1276 1277 atomic_set(&pending_req->pendcnt, nbio); 1278 blk_start_plug(&plug); 1279 1280 for (i = 0; i < nbio; i++) 1281 submit_bio(operation, biolist[i]); 1282 1283 /* Let the I/Os go.. */ 1284 blk_finish_plug(&plug); 1285 1286 if (operation == READ) 1287 blkif->st_rd_sect += preq.nr_sects; 1288 else if (operation & WRITE) 1289 blkif->st_wr_sect += preq.nr_sects; 1290 1291 return 0; 1292 1293 fail_flush: 1294 xen_blkbk_unmap(blkif, pending_req->segments, 1295 pending_req->nr_pages); 1296 fail_response: 1297 /* Haven't submitted any bio's yet. */ 1298 make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR); 1299 free_req(blkif, pending_req); 1300 msleep(1); /* back off a bit */ 1301 return -EIO; 1302 1303 fail_put_bio: 1304 for (i = 0; i < nbio; i++) 1305 bio_put(biolist[i]); 1306 atomic_set(&pending_req->pendcnt, 1); 1307 __end_block_io_op(pending_req, -EINVAL); 1308 msleep(1); /* back off a bit */ 1309 return -EIO; 1310 } 1311 1312 1313 1314 /* 1315 * Put a response on the ring on how the operation fared. 1316 */ 1317 static void make_response(struct xen_blkif *blkif, u64 id, 1318 unsigned short op, int st) 1319 { 1320 struct blkif_response resp; 1321 unsigned long flags; 1322 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1323 int notify; 1324 1325 resp.id = id; 1326 resp.operation = op; 1327 resp.status = st; 1328 1329 spin_lock_irqsave(&blkif->blk_ring_lock, flags); 1330 /* Place on the response ring for the relevant domain. */ 1331 switch (blkif->blk_protocol) { 1332 case BLKIF_PROTOCOL_NATIVE: 1333 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), 1334 &resp, sizeof(resp)); 1335 break; 1336 case BLKIF_PROTOCOL_X86_32: 1337 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), 1338 &resp, sizeof(resp)); 1339 break; 1340 case BLKIF_PROTOCOL_X86_64: 1341 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), 1342 &resp, sizeof(resp)); 1343 break; 1344 default: 1345 BUG(); 1346 } 1347 blk_rings->common.rsp_prod_pvt++; 1348 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); 1349 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); 1350 if (notify) 1351 notify_remote_via_irq(blkif->irq); 1352 } 1353 1354 static int __init xen_blkif_init(void) 1355 { 1356 int rc = 0; 1357 1358 if (!xen_domain()) 1359 return -ENODEV; 1360 1361 rc = xen_blkif_interface_init(); 1362 if (rc) 1363 goto failed_init; 1364 1365 rc = xen_blkif_xenbus_init(); 1366 if (rc) 1367 goto failed_init; 1368 1369 failed_init: 1370 return rc; 1371 } 1372 1373 module_init(xen_blkif_init); 1374 1375 MODULE_LICENSE("Dual BSD/GPL"); 1376 MODULE_ALIAS("xen-backend:vbd"); 1377