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 max_buffer_pages = 1024; 66 module_param_named(max_buffer_pages, 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 max_pgrants = 1056; 82 module_param_named(max_persistent_grants, max_pgrants, int, 0644); 83 MODULE_PARM_DESC(max_persistent_grants, 84 "Maximum number of grants to map persistently"); 85 86 /* 87 * How long a persistent grant is allowed to remain allocated without being in 88 * use. The time is in seconds, 0 means indefinitely long. 89 */ 90 91 static unsigned int pgrant_timeout = 60; 92 module_param_named(persistent_grant_unused_seconds, pgrant_timeout, 93 uint, 0644); 94 MODULE_PARM_DESC(persistent_grant_unused_seconds, 95 "Time in seconds an unused persistent grant is allowed to " 96 "remain allocated. Default is 60, 0 means unlimited."); 97 98 /* 99 * Maximum number of rings/queues blkback supports, allow as many queues as there 100 * are CPUs if user has not specified a value. 101 */ 102 unsigned int xenblk_max_queues; 103 module_param_named(max_queues, xenblk_max_queues, uint, 0644); 104 MODULE_PARM_DESC(max_queues, 105 "Maximum number of hardware queues per virtual disk." \ 106 "By default it is the number of online CPUs."); 107 108 /* 109 * Maximum order of pages to be used for the shared ring between front and 110 * backend, 4KB page granularity is used. 111 */ 112 unsigned int xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 113 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444); 114 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 115 /* 116 * The LRU mechanism to clean the lists of persistent grants needs to 117 * be executed periodically. The time interval between consecutive executions 118 * of the purge mechanism is set in ms. 119 */ 120 #define LRU_INTERVAL 100 121 122 /* 123 * When the persistent grants list is full we will remove unused grants 124 * from the list. The percent number of grants to be removed at each LRU 125 * execution. 126 */ 127 #define LRU_PERCENT_CLEAN 5 128 129 /* Run-time switchable: /sys/module/blkback/parameters/ */ 130 static unsigned int log_stats; 131 module_param(log_stats, int, 0644); 132 133 #define BLKBACK_INVALID_HANDLE (~0) 134 135 static inline bool persistent_gnt_timeout(struct persistent_gnt *persistent_gnt) 136 { 137 return pgrant_timeout && (jiffies - persistent_gnt->last_used >= 138 HZ * pgrant_timeout); 139 } 140 141 #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page))) 142 143 static int do_block_io_op(struct xen_blkif_ring *ring, unsigned int *eoi_flags); 144 static int dispatch_rw_block_io(struct xen_blkif_ring *ring, 145 struct blkif_request *req, 146 struct pending_req *pending_req); 147 static void make_response(struct xen_blkif_ring *ring, u64 id, 148 unsigned short op, int st); 149 150 #define foreach_grant_safe(pos, n, rbtree, node) \ 151 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \ 152 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \ 153 &(pos)->node != NULL; \ 154 (pos) = container_of(n, typeof(*(pos)), node), \ 155 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL) 156 157 158 /* 159 * We don't need locking around the persistent grant helpers 160 * because blkback uses a single-thread for each backend, so we 161 * can be sure that this functions will never be called recursively. 162 * 163 * The only exception to that is put_persistent_grant, that can be called 164 * from interrupt context (by xen_blkbk_unmap), so we have to use atomic 165 * bit operations to modify the flags of a persistent grant and to count 166 * the number of used grants. 167 */ 168 static int add_persistent_gnt(struct xen_blkif_ring *ring, 169 struct persistent_gnt *persistent_gnt) 170 { 171 struct rb_node **new = NULL, *parent = NULL; 172 struct persistent_gnt *this; 173 struct xen_blkif *blkif = ring->blkif; 174 175 if (ring->persistent_gnt_c >= max_pgrants) { 176 if (!blkif->vbd.overflow_max_grants) 177 blkif->vbd.overflow_max_grants = 1; 178 return -EBUSY; 179 } 180 /* Figure out where to put new node */ 181 new = &ring->persistent_gnts.rb_node; 182 while (*new) { 183 this = container_of(*new, struct persistent_gnt, node); 184 185 parent = *new; 186 if (persistent_gnt->gnt < this->gnt) 187 new = &((*new)->rb_left); 188 else if (persistent_gnt->gnt > this->gnt) 189 new = &((*new)->rb_right); 190 else { 191 pr_alert_ratelimited("trying to add a gref that's already in the tree\n"); 192 return -EINVAL; 193 } 194 } 195 196 persistent_gnt->active = true; 197 /* Add new node and rebalance tree. */ 198 rb_link_node(&(persistent_gnt->node), parent, new); 199 rb_insert_color(&(persistent_gnt->node), &ring->persistent_gnts); 200 ring->persistent_gnt_c++; 201 atomic_inc(&ring->persistent_gnt_in_use); 202 return 0; 203 } 204 205 static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring, 206 grant_ref_t gref) 207 { 208 struct persistent_gnt *data; 209 struct rb_node *node = NULL; 210 211 node = ring->persistent_gnts.rb_node; 212 while (node) { 213 data = container_of(node, struct persistent_gnt, node); 214 215 if (gref < data->gnt) 216 node = node->rb_left; 217 else if (gref > data->gnt) 218 node = node->rb_right; 219 else { 220 if (data->active) { 221 pr_alert_ratelimited("requesting a grant already in use\n"); 222 return NULL; 223 } 224 data->active = true; 225 atomic_inc(&ring->persistent_gnt_in_use); 226 return data; 227 } 228 } 229 return NULL; 230 } 231 232 static void put_persistent_gnt(struct xen_blkif_ring *ring, 233 struct persistent_gnt *persistent_gnt) 234 { 235 if (!persistent_gnt->active) 236 pr_alert_ratelimited("freeing a grant already unused\n"); 237 persistent_gnt->last_used = jiffies; 238 persistent_gnt->active = false; 239 atomic_dec(&ring->persistent_gnt_in_use); 240 } 241 242 static void free_persistent_gnts(struct xen_blkif_ring *ring, struct rb_root *root, 243 unsigned int num) 244 { 245 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 246 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 247 struct persistent_gnt *persistent_gnt; 248 struct rb_node *n; 249 int segs_to_unmap = 0; 250 struct gntab_unmap_queue_data unmap_data; 251 252 unmap_data.pages = pages; 253 unmap_data.unmap_ops = unmap; 254 unmap_data.kunmap_ops = NULL; 255 256 foreach_grant_safe(persistent_gnt, n, root, node) { 257 BUG_ON(persistent_gnt->handle == 258 BLKBACK_INVALID_HANDLE); 259 gnttab_set_unmap_op(&unmap[segs_to_unmap], 260 (unsigned long) pfn_to_kaddr(page_to_pfn( 261 persistent_gnt->page)), 262 GNTMAP_host_map, 263 persistent_gnt->handle); 264 265 pages[segs_to_unmap] = persistent_gnt->page; 266 267 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST || 268 !rb_next(&persistent_gnt->node)) { 269 270 unmap_data.count = segs_to_unmap; 271 BUG_ON(gnttab_unmap_refs_sync(&unmap_data)); 272 273 gnttab_page_cache_put(&ring->free_pages, pages, 274 segs_to_unmap); 275 segs_to_unmap = 0; 276 } 277 278 rb_erase(&persistent_gnt->node, root); 279 kfree(persistent_gnt); 280 num--; 281 } 282 BUG_ON(num != 0); 283 } 284 285 void xen_blkbk_unmap_purged_grants(struct work_struct *work) 286 { 287 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 288 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 289 struct persistent_gnt *persistent_gnt; 290 int segs_to_unmap = 0; 291 struct xen_blkif_ring *ring = container_of(work, typeof(*ring), persistent_purge_work); 292 struct gntab_unmap_queue_data unmap_data; 293 294 unmap_data.pages = pages; 295 unmap_data.unmap_ops = unmap; 296 unmap_data.kunmap_ops = NULL; 297 298 while(!list_empty(&ring->persistent_purge_list)) { 299 persistent_gnt = list_first_entry(&ring->persistent_purge_list, 300 struct persistent_gnt, 301 remove_node); 302 list_del(&persistent_gnt->remove_node); 303 304 gnttab_set_unmap_op(&unmap[segs_to_unmap], 305 vaddr(persistent_gnt->page), 306 GNTMAP_host_map, 307 persistent_gnt->handle); 308 309 pages[segs_to_unmap] = persistent_gnt->page; 310 311 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) { 312 unmap_data.count = segs_to_unmap; 313 BUG_ON(gnttab_unmap_refs_sync(&unmap_data)); 314 gnttab_page_cache_put(&ring->free_pages, pages, 315 segs_to_unmap); 316 segs_to_unmap = 0; 317 } 318 kfree(persistent_gnt); 319 } 320 if (segs_to_unmap > 0) { 321 unmap_data.count = segs_to_unmap; 322 BUG_ON(gnttab_unmap_refs_sync(&unmap_data)); 323 gnttab_page_cache_put(&ring->free_pages, pages, segs_to_unmap); 324 } 325 } 326 327 static void purge_persistent_gnt(struct xen_blkif_ring *ring) 328 { 329 struct persistent_gnt *persistent_gnt; 330 struct rb_node *n; 331 unsigned int num_clean, total; 332 bool scan_used = false; 333 struct rb_root *root; 334 335 if (work_busy(&ring->persistent_purge_work)) { 336 pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n"); 337 goto out; 338 } 339 340 if (ring->persistent_gnt_c < max_pgrants || 341 (ring->persistent_gnt_c == max_pgrants && 342 !ring->blkif->vbd.overflow_max_grants)) { 343 num_clean = 0; 344 } else { 345 num_clean = (max_pgrants / 100) * LRU_PERCENT_CLEAN; 346 num_clean = ring->persistent_gnt_c - max_pgrants + num_clean; 347 num_clean = min(ring->persistent_gnt_c, num_clean); 348 pr_debug("Going to purge at least %u persistent grants\n", 349 num_clean); 350 } 351 352 /* 353 * At this point, we can assure that there will be no calls 354 * to get_persistent_grant (because we are executing this code from 355 * xen_blkif_schedule), there can only be calls to put_persistent_gnt, 356 * which means that the number of currently used grants will go down, 357 * but never up, so we will always be able to remove the requested 358 * number of grants. 359 */ 360 361 total = 0; 362 363 BUG_ON(!list_empty(&ring->persistent_purge_list)); 364 root = &ring->persistent_gnts; 365 purge_list: 366 foreach_grant_safe(persistent_gnt, n, root, node) { 367 BUG_ON(persistent_gnt->handle == 368 BLKBACK_INVALID_HANDLE); 369 370 if (persistent_gnt->active) 371 continue; 372 if (!scan_used && !persistent_gnt_timeout(persistent_gnt)) 373 continue; 374 if (scan_used && total >= num_clean) 375 continue; 376 377 rb_erase(&persistent_gnt->node, root); 378 list_add(&persistent_gnt->remove_node, 379 &ring->persistent_purge_list); 380 total++; 381 } 382 /* 383 * Check whether we also need to start cleaning 384 * grants that were used since last purge in order to cope 385 * with the requested num 386 */ 387 if (!scan_used && total < num_clean) { 388 pr_debug("Still missing %u purged frames\n", num_clean - total); 389 scan_used = true; 390 goto purge_list; 391 } 392 393 if (total) { 394 ring->persistent_gnt_c -= total; 395 ring->blkif->vbd.overflow_max_grants = 0; 396 397 /* We can defer this work */ 398 schedule_work(&ring->persistent_purge_work); 399 pr_debug("Purged %u/%u\n", num_clean, total); 400 } 401 402 out: 403 return; 404 } 405 406 /* 407 * Retrieve from the 'pending_reqs' a free pending_req structure to be used. 408 */ 409 static struct pending_req *alloc_req(struct xen_blkif_ring *ring) 410 { 411 struct pending_req *req = NULL; 412 unsigned long flags; 413 414 spin_lock_irqsave(&ring->pending_free_lock, flags); 415 if (!list_empty(&ring->pending_free)) { 416 req = list_entry(ring->pending_free.next, struct pending_req, 417 free_list); 418 list_del(&req->free_list); 419 } 420 spin_unlock_irqrestore(&ring->pending_free_lock, flags); 421 return req; 422 } 423 424 /* 425 * Return the 'pending_req' structure back to the freepool. We also 426 * wake up the thread if it was waiting for a free page. 427 */ 428 static void free_req(struct xen_blkif_ring *ring, struct pending_req *req) 429 { 430 unsigned long flags; 431 int was_empty; 432 433 spin_lock_irqsave(&ring->pending_free_lock, flags); 434 was_empty = list_empty(&ring->pending_free); 435 list_add(&req->free_list, &ring->pending_free); 436 spin_unlock_irqrestore(&ring->pending_free_lock, flags); 437 if (was_empty) 438 wake_up(&ring->pending_free_wq); 439 } 440 441 /* 442 * Routines for managing virtual block devices (vbds). 443 */ 444 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, 445 int operation) 446 { 447 struct xen_vbd *vbd = &blkif->vbd; 448 int rc = -EACCES; 449 450 if ((operation != REQ_OP_READ) && vbd->readonly) 451 goto out; 452 453 if (likely(req->nr_sects)) { 454 blkif_sector_t end = req->sector_number + req->nr_sects; 455 456 if (unlikely(end < req->sector_number)) 457 goto out; 458 if (unlikely(end > vbd_sz(vbd))) 459 goto out; 460 } 461 462 req->dev = vbd->pdevice; 463 req->bdev = vbd->bdev; 464 rc = 0; 465 466 out: 467 return rc; 468 } 469 470 static void xen_vbd_resize(struct xen_blkif *blkif) 471 { 472 struct xen_vbd *vbd = &blkif->vbd; 473 struct xenbus_transaction xbt; 474 int err; 475 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); 476 unsigned long long new_size = vbd_sz(vbd); 477 478 pr_info("VBD Resize: Domid: %d, Device: (%d, %d)\n", 479 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); 480 pr_info("VBD Resize: new size %llu\n", new_size); 481 vbd->size = new_size; 482 again: 483 err = xenbus_transaction_start(&xbt); 484 if (err) { 485 pr_warn("Error starting transaction\n"); 486 return; 487 } 488 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 489 (unsigned long long)vbd_sz(vbd)); 490 if (err) { 491 pr_warn("Error writing new size\n"); 492 goto abort; 493 } 494 /* 495 * Write the current state; we will use this to synchronize 496 * the front-end. If the current state is "connected" the 497 * front-end will get the new size information online. 498 */ 499 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); 500 if (err) { 501 pr_warn("Error writing the state\n"); 502 goto abort; 503 } 504 505 err = xenbus_transaction_end(xbt, 0); 506 if (err == -EAGAIN) 507 goto again; 508 if (err) 509 pr_warn("Error ending transaction\n"); 510 return; 511 abort: 512 xenbus_transaction_end(xbt, 1); 513 } 514 515 /* 516 * Notification from the guest OS. 517 */ 518 static void blkif_notify_work(struct xen_blkif_ring *ring) 519 { 520 ring->waiting_reqs = 1; 521 wake_up(&ring->wq); 522 } 523 524 irqreturn_t xen_blkif_be_int(int irq, void *dev_id) 525 { 526 blkif_notify_work(dev_id); 527 return IRQ_HANDLED; 528 } 529 530 /* 531 * SCHEDULER FUNCTIONS 532 */ 533 534 static void print_stats(struct xen_blkif_ring *ring) 535 { 536 pr_info("(%s): oo %3llu | rd %4llu | wr %4llu | f %4llu" 537 " | ds %4llu | pg: %4u/%4d\n", 538 current->comm, ring->st_oo_req, 539 ring->st_rd_req, ring->st_wr_req, 540 ring->st_f_req, ring->st_ds_req, 541 ring->persistent_gnt_c, max_pgrants); 542 ring->st_print = jiffies + msecs_to_jiffies(10 * 1000); 543 ring->st_rd_req = 0; 544 ring->st_wr_req = 0; 545 ring->st_oo_req = 0; 546 ring->st_ds_req = 0; 547 } 548 549 int xen_blkif_schedule(void *arg) 550 { 551 struct xen_blkif_ring *ring = arg; 552 struct xen_blkif *blkif = ring->blkif; 553 struct xen_vbd *vbd = &blkif->vbd; 554 unsigned long timeout; 555 int ret; 556 bool do_eoi; 557 unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS; 558 559 set_freezable(); 560 while (!kthread_should_stop()) { 561 if (try_to_freeze()) 562 continue; 563 if (unlikely(vbd->size != vbd_sz(vbd))) 564 xen_vbd_resize(blkif); 565 566 timeout = msecs_to_jiffies(LRU_INTERVAL); 567 568 timeout = wait_event_interruptible_timeout( 569 ring->wq, 570 ring->waiting_reqs || kthread_should_stop(), 571 timeout); 572 if (timeout == 0) 573 goto purge_gnt_list; 574 timeout = wait_event_interruptible_timeout( 575 ring->pending_free_wq, 576 !list_empty(&ring->pending_free) || 577 kthread_should_stop(), 578 timeout); 579 if (timeout == 0) 580 goto purge_gnt_list; 581 582 do_eoi = ring->waiting_reqs; 583 584 ring->waiting_reqs = 0; 585 smp_mb(); /* clear flag *before* checking for work */ 586 587 ret = do_block_io_op(ring, &eoi_flags); 588 if (ret > 0) 589 ring->waiting_reqs = 1; 590 if (ret == -EACCES) 591 wait_event_interruptible(ring->shutdown_wq, 592 kthread_should_stop()); 593 594 if (do_eoi && !ring->waiting_reqs) { 595 xen_irq_lateeoi(ring->irq, eoi_flags); 596 eoi_flags |= XEN_EOI_FLAG_SPURIOUS; 597 } 598 599 purge_gnt_list: 600 if (blkif->vbd.feature_gnt_persistent && 601 time_after(jiffies, ring->next_lru)) { 602 purge_persistent_gnt(ring); 603 ring->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL); 604 } 605 606 /* Shrink the free pages pool if it is too large. */ 607 if (time_before(jiffies, blkif->buffer_squeeze_end)) 608 gnttab_page_cache_shrink(&ring->free_pages, 0); 609 else 610 gnttab_page_cache_shrink(&ring->free_pages, 611 max_buffer_pages); 612 613 if (log_stats && time_after(jiffies, ring->st_print)) 614 print_stats(ring); 615 } 616 617 /* Drain pending purge work */ 618 flush_work(&ring->persistent_purge_work); 619 620 if (log_stats) 621 print_stats(ring); 622 623 ring->xenblkd = NULL; 624 625 return 0; 626 } 627 628 /* 629 * Remove persistent grants and empty the pool of free pages 630 */ 631 void xen_blkbk_free_caches(struct xen_blkif_ring *ring) 632 { 633 /* Free all persistent grant pages */ 634 if (!RB_EMPTY_ROOT(&ring->persistent_gnts)) 635 free_persistent_gnts(ring, &ring->persistent_gnts, 636 ring->persistent_gnt_c); 637 638 BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts)); 639 ring->persistent_gnt_c = 0; 640 641 /* Since we are shutting down remove all pages from the buffer */ 642 gnttab_page_cache_shrink(&ring->free_pages, 0 /* All */); 643 } 644 645 static unsigned int xen_blkbk_unmap_prepare( 646 struct xen_blkif_ring *ring, 647 struct grant_page **pages, 648 unsigned int num, 649 struct gnttab_unmap_grant_ref *unmap_ops, 650 struct page **unmap_pages) 651 { 652 unsigned int i, invcount = 0; 653 654 for (i = 0; i < num; i++) { 655 if (pages[i]->persistent_gnt != NULL) { 656 put_persistent_gnt(ring, pages[i]->persistent_gnt); 657 continue; 658 } 659 if (pages[i]->handle == BLKBACK_INVALID_HANDLE) 660 continue; 661 unmap_pages[invcount] = pages[i]->page; 662 gnttab_set_unmap_op(&unmap_ops[invcount], vaddr(pages[i]->page), 663 GNTMAP_host_map, pages[i]->handle); 664 pages[i]->handle = BLKBACK_INVALID_HANDLE; 665 invcount++; 666 } 667 668 return invcount; 669 } 670 671 static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_queue_data *data) 672 { 673 struct pending_req *pending_req = (struct pending_req *)(data->data); 674 struct xen_blkif_ring *ring = pending_req->ring; 675 struct xen_blkif *blkif = ring->blkif; 676 677 /* BUG_ON used to reproduce existing behaviour, 678 but is this the best way to deal with this? */ 679 BUG_ON(result); 680 681 gnttab_page_cache_put(&ring->free_pages, data->pages, data->count); 682 make_response(ring, pending_req->id, 683 pending_req->operation, pending_req->status); 684 free_req(ring, pending_req); 685 /* 686 * Make sure the request is freed before releasing blkif, 687 * or there could be a race between free_req and the 688 * cleanup done in xen_blkif_free during shutdown. 689 * 690 * NB: The fact that we might try to wake up pending_free_wq 691 * before drain_complete (in case there's a drain going on) 692 * it's not a problem with our current implementation 693 * because we can assure there's no thread waiting on 694 * pending_free_wq if there's a drain going on, but it has 695 * to be taken into account if the current model is changed. 696 */ 697 if (atomic_dec_and_test(&ring->inflight) && atomic_read(&blkif->drain)) { 698 complete(&blkif->drain_complete); 699 } 700 xen_blkif_put(blkif); 701 } 702 703 static void xen_blkbk_unmap_and_respond(struct pending_req *req) 704 { 705 struct gntab_unmap_queue_data* work = &req->gnttab_unmap_data; 706 struct xen_blkif_ring *ring = req->ring; 707 struct grant_page **pages = req->segments; 708 unsigned int invcount; 709 710 invcount = xen_blkbk_unmap_prepare(ring, pages, req->nr_segs, 711 req->unmap, req->unmap_pages); 712 713 work->data = req; 714 work->done = xen_blkbk_unmap_and_respond_callback; 715 work->unmap_ops = req->unmap; 716 work->kunmap_ops = NULL; 717 work->pages = req->unmap_pages; 718 work->count = invcount; 719 720 gnttab_unmap_refs_async(&req->gnttab_unmap_data); 721 } 722 723 724 /* 725 * Unmap the grant references. 726 * 727 * This could accumulate ops up to the batch size to reduce the number 728 * of hypercalls, but since this is only used in error paths there's 729 * no real need. 730 */ 731 static void xen_blkbk_unmap(struct xen_blkif_ring *ring, 732 struct grant_page *pages[], 733 int num) 734 { 735 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 736 struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 737 unsigned int invcount = 0; 738 int ret; 739 740 while (num) { 741 unsigned int batch = min(num, BLKIF_MAX_SEGMENTS_PER_REQUEST); 742 743 invcount = xen_blkbk_unmap_prepare(ring, pages, batch, 744 unmap, unmap_pages); 745 if (invcount) { 746 ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount); 747 BUG_ON(ret); 748 gnttab_page_cache_put(&ring->free_pages, unmap_pages, 749 invcount); 750 } 751 pages += batch; 752 num -= batch; 753 } 754 } 755 756 static int xen_blkbk_map(struct xen_blkif_ring *ring, 757 struct grant_page *pages[], 758 int num, bool ro) 759 { 760 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 761 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 762 struct persistent_gnt *persistent_gnt = NULL; 763 phys_addr_t addr = 0; 764 int i, seg_idx, new_map_idx; 765 int segs_to_map = 0; 766 int ret = 0; 767 int last_map = 0, map_until = 0; 768 int use_persistent_gnts; 769 struct xen_blkif *blkif = ring->blkif; 770 771 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent); 772 773 /* 774 * Fill out preq.nr_sects with proper amount of sectors, and setup 775 * assign map[..] with the PFN of the page in our domain with the 776 * corresponding grant reference for each page. 777 */ 778 again: 779 for (i = map_until; i < num; i++) { 780 uint32_t flags; 781 782 if (use_persistent_gnts) { 783 persistent_gnt = get_persistent_gnt( 784 ring, 785 pages[i]->gref); 786 } 787 788 if (persistent_gnt) { 789 /* 790 * We are using persistent grants and 791 * the grant is already mapped 792 */ 793 pages[i]->page = persistent_gnt->page; 794 pages[i]->persistent_gnt = persistent_gnt; 795 } else { 796 if (gnttab_page_cache_get(&ring->free_pages, 797 &pages[i]->page)) { 798 gnttab_page_cache_put(&ring->free_pages, 799 pages_to_gnt, 800 segs_to_map); 801 ret = -ENOMEM; 802 goto out; 803 } 804 addr = vaddr(pages[i]->page); 805 pages_to_gnt[segs_to_map] = pages[i]->page; 806 pages[i]->persistent_gnt = NULL; 807 flags = GNTMAP_host_map; 808 if (!use_persistent_gnts && ro) 809 flags |= GNTMAP_readonly; 810 gnttab_set_map_op(&map[segs_to_map++], addr, 811 flags, pages[i]->gref, 812 blkif->domid); 813 } 814 map_until = i + 1; 815 if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST) 816 break; 817 } 818 819 if (segs_to_map) 820 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map); 821 822 /* 823 * Now swizzle the MFN in our domain with the MFN from the other domain 824 * so that when we access vaddr(pending_req,i) it has the contents of 825 * the page from the other domain. 826 */ 827 for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) { 828 if (!pages[seg_idx]->persistent_gnt) { 829 /* This is a newly mapped grant */ 830 BUG_ON(new_map_idx >= segs_to_map); 831 if (unlikely(map[new_map_idx].status != 0)) { 832 pr_debug("invalid buffer -- could not remap it\n"); 833 gnttab_page_cache_put(&ring->free_pages, 834 &pages[seg_idx]->page, 1); 835 pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE; 836 ret |= !ret; 837 goto next; 838 } 839 pages[seg_idx]->handle = map[new_map_idx].handle; 840 } else { 841 continue; 842 } 843 if (use_persistent_gnts && 844 ring->persistent_gnt_c < max_pgrants) { 845 /* 846 * We are using persistent grants, the grant is 847 * not mapped but we might have room for it. 848 */ 849 persistent_gnt = kmalloc(sizeof(struct persistent_gnt), 850 GFP_KERNEL); 851 if (!persistent_gnt) { 852 /* 853 * If we don't have enough memory to 854 * allocate the persistent_gnt struct 855 * map this grant non-persistenly 856 */ 857 goto next; 858 } 859 persistent_gnt->gnt = map[new_map_idx].ref; 860 persistent_gnt->handle = map[new_map_idx].handle; 861 persistent_gnt->page = pages[seg_idx]->page; 862 if (add_persistent_gnt(ring, 863 persistent_gnt)) { 864 kfree(persistent_gnt); 865 persistent_gnt = NULL; 866 goto next; 867 } 868 pages[seg_idx]->persistent_gnt = persistent_gnt; 869 pr_debug("grant %u added to the tree of persistent grants, using %u/%u\n", 870 persistent_gnt->gnt, ring->persistent_gnt_c, 871 max_pgrants); 872 goto next; 873 } 874 if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) { 875 blkif->vbd.overflow_max_grants = 1; 876 pr_debug("domain %u, device %#x is using maximum number of persistent grants\n", 877 blkif->domid, blkif->vbd.handle); 878 } 879 /* 880 * We could not map this grant persistently, so use it as 881 * a non-persistent grant. 882 */ 883 next: 884 new_map_idx++; 885 } 886 segs_to_map = 0; 887 last_map = map_until; 888 if (!ret && map_until != num) 889 goto again; 890 891 out: 892 for (i = last_map; i < num; i++) { 893 /* Don't zap current batch's valid persistent grants. */ 894 if(i >= last_map + segs_to_map) 895 pages[i]->persistent_gnt = NULL; 896 pages[i]->handle = BLKBACK_INVALID_HANDLE; 897 } 898 899 return ret; 900 } 901 902 static int xen_blkbk_map_seg(struct pending_req *pending_req) 903 { 904 int rc; 905 906 rc = xen_blkbk_map(pending_req->ring, pending_req->segments, 907 pending_req->nr_segs, 908 (pending_req->operation != BLKIF_OP_READ)); 909 910 return rc; 911 } 912 913 static int xen_blkbk_parse_indirect(struct blkif_request *req, 914 struct pending_req *pending_req, 915 struct seg_buf seg[], 916 struct phys_req *preq) 917 { 918 struct grant_page **pages = pending_req->indirect_pages; 919 struct xen_blkif_ring *ring = pending_req->ring; 920 int indirect_grefs, rc, n, nseg, i; 921 struct blkif_request_segment *segments = NULL; 922 923 nseg = pending_req->nr_segs; 924 indirect_grefs = INDIRECT_PAGES(nseg); 925 BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); 926 927 for (i = 0; i < indirect_grefs; i++) 928 pages[i]->gref = req->u.indirect.indirect_grefs[i]; 929 930 rc = xen_blkbk_map(ring, pages, indirect_grefs, true); 931 if (rc) 932 goto unmap; 933 934 for (n = 0, i = 0; n < nseg; n++) { 935 uint8_t first_sect, last_sect; 936 937 if ((n % SEGS_PER_INDIRECT_FRAME) == 0) { 938 /* Map indirect segments */ 939 if (segments) 940 kunmap_atomic(segments); 941 segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page); 942 } 943 i = n % SEGS_PER_INDIRECT_FRAME; 944 945 pending_req->segments[n]->gref = segments[i].gref; 946 947 first_sect = READ_ONCE(segments[i].first_sect); 948 last_sect = READ_ONCE(segments[i].last_sect); 949 if (last_sect >= (XEN_PAGE_SIZE >> 9) || last_sect < first_sect) { 950 rc = -EINVAL; 951 goto unmap; 952 } 953 954 seg[n].nsec = last_sect - first_sect + 1; 955 seg[n].offset = first_sect << 9; 956 preq->nr_sects += seg[n].nsec; 957 } 958 959 unmap: 960 if (segments) 961 kunmap_atomic(segments); 962 xen_blkbk_unmap(ring, pages, indirect_grefs); 963 return rc; 964 } 965 966 static int dispatch_discard_io(struct xen_blkif_ring *ring, 967 struct blkif_request *req) 968 { 969 int err = 0; 970 int status = BLKIF_RSP_OKAY; 971 struct xen_blkif *blkif = ring->blkif; 972 struct block_device *bdev = blkif->vbd.bdev; 973 unsigned long secure; 974 struct phys_req preq; 975 976 xen_blkif_get(blkif); 977 978 preq.sector_number = req->u.discard.sector_number; 979 preq.nr_sects = req->u.discard.nr_sectors; 980 981 err = xen_vbd_translate(&preq, blkif, REQ_OP_WRITE); 982 if (err) { 983 pr_warn("access denied: DISCARD [%llu->%llu] on dev=%04x\n", 984 preq.sector_number, 985 preq.sector_number + preq.nr_sects, blkif->vbd.pdevice); 986 goto fail_response; 987 } 988 ring->st_ds_req++; 989 990 secure = (blkif->vbd.discard_secure && 991 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? 992 BLKDEV_DISCARD_SECURE : 0; 993 994 err = blkdev_issue_discard(bdev, req->u.discard.sector_number, 995 req->u.discard.nr_sectors, 996 GFP_KERNEL, secure); 997 fail_response: 998 if (err == -EOPNOTSUPP) { 999 pr_debug("discard op failed, not supported\n"); 1000 status = BLKIF_RSP_EOPNOTSUPP; 1001 } else if (err) 1002 status = BLKIF_RSP_ERROR; 1003 1004 make_response(ring, req->u.discard.id, req->operation, status); 1005 xen_blkif_put(blkif); 1006 return err; 1007 } 1008 1009 static int dispatch_other_io(struct xen_blkif_ring *ring, 1010 struct blkif_request *req, 1011 struct pending_req *pending_req) 1012 { 1013 free_req(ring, pending_req); 1014 make_response(ring, req->u.other.id, req->operation, 1015 BLKIF_RSP_EOPNOTSUPP); 1016 return -EIO; 1017 } 1018 1019 static void xen_blk_drain_io(struct xen_blkif_ring *ring) 1020 { 1021 struct xen_blkif *blkif = ring->blkif; 1022 1023 atomic_set(&blkif->drain, 1); 1024 do { 1025 if (atomic_read(&ring->inflight) == 0) 1026 break; 1027 wait_for_completion_interruptible_timeout( 1028 &blkif->drain_complete, HZ); 1029 1030 if (!atomic_read(&blkif->drain)) 1031 break; 1032 } while (!kthread_should_stop()); 1033 atomic_set(&blkif->drain, 0); 1034 } 1035 1036 static void __end_block_io_op(struct pending_req *pending_req, 1037 blk_status_t error) 1038 { 1039 /* An error fails the entire request. */ 1040 if (pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE && 1041 error == BLK_STS_NOTSUPP) { 1042 pr_debug("flush diskcache op failed, not supported\n"); 1043 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->ring->blkif->be, 0); 1044 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 1045 } else if (pending_req->operation == BLKIF_OP_WRITE_BARRIER && 1046 error == BLK_STS_NOTSUPP) { 1047 pr_debug("write barrier op failed, not supported\n"); 1048 xen_blkbk_barrier(XBT_NIL, pending_req->ring->blkif->be, 0); 1049 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 1050 } else if (error) { 1051 pr_debug("Buffer not up-to-date at end of operation," 1052 " error=%d\n", error); 1053 pending_req->status = BLKIF_RSP_ERROR; 1054 } 1055 1056 /* 1057 * If all of the bio's have completed it is time to unmap 1058 * the grant references associated with 'request' and provide 1059 * the proper response on the ring. 1060 */ 1061 if (atomic_dec_and_test(&pending_req->pendcnt)) 1062 xen_blkbk_unmap_and_respond(pending_req); 1063 } 1064 1065 /* 1066 * bio callback. 1067 */ 1068 static void end_block_io_op(struct bio *bio) 1069 { 1070 __end_block_io_op(bio->bi_private, bio->bi_status); 1071 bio_put(bio); 1072 } 1073 1074 1075 1076 /* 1077 * Function to copy the from the ring buffer the 'struct blkif_request' 1078 * (which has the sectors we want, number of them, grant references, etc), 1079 * and transmute it to the block API to hand it over to the proper block disk. 1080 */ 1081 static int 1082 __do_block_io_op(struct xen_blkif_ring *ring, unsigned int *eoi_flags) 1083 { 1084 union blkif_back_rings *blk_rings = &ring->blk_rings; 1085 struct blkif_request req; 1086 struct pending_req *pending_req; 1087 RING_IDX rc, rp; 1088 int more_to_do = 0; 1089 1090 rc = blk_rings->common.req_cons; 1091 rp = blk_rings->common.sring->req_prod; 1092 rmb(); /* Ensure we see queued requests up to 'rp'. */ 1093 1094 if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) { 1095 rc = blk_rings->common.rsp_prod_pvt; 1096 pr_warn("Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n", 1097 rp, rc, rp - rc, ring->blkif->vbd.pdevice); 1098 return -EACCES; 1099 } 1100 while (rc != rp) { 1101 1102 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) 1103 break; 1104 1105 /* We've seen a request, so clear spurious eoi flag. */ 1106 *eoi_flags &= ~XEN_EOI_FLAG_SPURIOUS; 1107 1108 if (kthread_should_stop()) { 1109 more_to_do = 1; 1110 break; 1111 } 1112 1113 pending_req = alloc_req(ring); 1114 if (NULL == pending_req) { 1115 ring->st_oo_req++; 1116 more_to_do = 1; 1117 break; 1118 } 1119 1120 switch (ring->blkif->blk_protocol) { 1121 case BLKIF_PROTOCOL_NATIVE: 1122 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); 1123 break; 1124 case BLKIF_PROTOCOL_X86_32: 1125 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); 1126 break; 1127 case BLKIF_PROTOCOL_X86_64: 1128 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); 1129 break; 1130 default: 1131 BUG(); 1132 } 1133 blk_rings->common.req_cons = ++rc; /* before make_response() */ 1134 1135 /* Apply all sanity checks to /private copy/ of request. */ 1136 barrier(); 1137 1138 switch (req.operation) { 1139 case BLKIF_OP_READ: 1140 case BLKIF_OP_WRITE: 1141 case BLKIF_OP_WRITE_BARRIER: 1142 case BLKIF_OP_FLUSH_DISKCACHE: 1143 case BLKIF_OP_INDIRECT: 1144 if (dispatch_rw_block_io(ring, &req, pending_req)) 1145 goto done; 1146 break; 1147 case BLKIF_OP_DISCARD: 1148 free_req(ring, pending_req); 1149 if (dispatch_discard_io(ring, &req)) 1150 goto done; 1151 break; 1152 default: 1153 if (dispatch_other_io(ring, &req, pending_req)) 1154 goto done; 1155 break; 1156 } 1157 1158 /* Yield point for this unbounded loop. */ 1159 cond_resched(); 1160 } 1161 done: 1162 return more_to_do; 1163 } 1164 1165 static int 1166 do_block_io_op(struct xen_blkif_ring *ring, unsigned int *eoi_flags) 1167 { 1168 union blkif_back_rings *blk_rings = &ring->blk_rings; 1169 int more_to_do; 1170 1171 do { 1172 more_to_do = __do_block_io_op(ring, eoi_flags); 1173 if (more_to_do) 1174 break; 1175 1176 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); 1177 } while (more_to_do); 1178 1179 return more_to_do; 1180 } 1181 /* 1182 * Transmutation of the 'struct blkif_request' to a proper 'struct bio' 1183 * and call the 'submit_bio' to pass it to the underlying storage. 1184 */ 1185 static int dispatch_rw_block_io(struct xen_blkif_ring *ring, 1186 struct blkif_request *req, 1187 struct pending_req *pending_req) 1188 { 1189 struct phys_req preq; 1190 struct seg_buf *seg = pending_req->seg; 1191 unsigned int nseg; 1192 struct bio *bio = NULL; 1193 struct bio **biolist = pending_req->biolist; 1194 int i, nbio = 0; 1195 int operation; 1196 int operation_flags = 0; 1197 struct blk_plug plug; 1198 bool drain = false; 1199 struct grant_page **pages = pending_req->segments; 1200 unsigned short req_operation; 1201 1202 req_operation = req->operation == BLKIF_OP_INDIRECT ? 1203 req->u.indirect.indirect_op : req->operation; 1204 1205 if ((req->operation == BLKIF_OP_INDIRECT) && 1206 (req_operation != BLKIF_OP_READ) && 1207 (req_operation != BLKIF_OP_WRITE)) { 1208 pr_debug("Invalid indirect operation (%u)\n", req_operation); 1209 goto fail_response; 1210 } 1211 1212 switch (req_operation) { 1213 case BLKIF_OP_READ: 1214 ring->st_rd_req++; 1215 operation = REQ_OP_READ; 1216 break; 1217 case BLKIF_OP_WRITE: 1218 ring->st_wr_req++; 1219 operation = REQ_OP_WRITE; 1220 operation_flags = REQ_SYNC | REQ_IDLE; 1221 break; 1222 case BLKIF_OP_WRITE_BARRIER: 1223 drain = true; 1224 fallthrough; 1225 case BLKIF_OP_FLUSH_DISKCACHE: 1226 ring->st_f_req++; 1227 operation = REQ_OP_WRITE; 1228 operation_flags = REQ_PREFLUSH; 1229 break; 1230 default: 1231 operation = 0; /* make gcc happy */ 1232 goto fail_response; 1233 break; 1234 } 1235 1236 /* Check that the number of segments is sane. */ 1237 nseg = req->operation == BLKIF_OP_INDIRECT ? 1238 req->u.indirect.nr_segments : req->u.rw.nr_segments; 1239 1240 if (unlikely(nseg == 0 && operation_flags != REQ_PREFLUSH) || 1241 unlikely((req->operation != BLKIF_OP_INDIRECT) && 1242 (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) || 1243 unlikely((req->operation == BLKIF_OP_INDIRECT) && 1244 (nseg > MAX_INDIRECT_SEGMENTS))) { 1245 pr_debug("Bad number of segments in request (%d)\n", nseg); 1246 /* Haven't submitted any bio's yet. */ 1247 goto fail_response; 1248 } 1249 1250 preq.nr_sects = 0; 1251 1252 pending_req->ring = ring; 1253 pending_req->id = req->u.rw.id; 1254 pending_req->operation = req_operation; 1255 pending_req->status = BLKIF_RSP_OKAY; 1256 pending_req->nr_segs = nseg; 1257 1258 if (req->operation != BLKIF_OP_INDIRECT) { 1259 preq.dev = req->u.rw.handle; 1260 preq.sector_number = req->u.rw.sector_number; 1261 for (i = 0; i < nseg; i++) { 1262 pages[i]->gref = req->u.rw.seg[i].gref; 1263 seg[i].nsec = req->u.rw.seg[i].last_sect - 1264 req->u.rw.seg[i].first_sect + 1; 1265 seg[i].offset = (req->u.rw.seg[i].first_sect << 9); 1266 if ((req->u.rw.seg[i].last_sect >= (XEN_PAGE_SIZE >> 9)) || 1267 (req->u.rw.seg[i].last_sect < 1268 req->u.rw.seg[i].first_sect)) 1269 goto fail_response; 1270 preq.nr_sects += seg[i].nsec; 1271 } 1272 } else { 1273 preq.dev = req->u.indirect.handle; 1274 preq.sector_number = req->u.indirect.sector_number; 1275 if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq)) 1276 goto fail_response; 1277 } 1278 1279 if (xen_vbd_translate(&preq, ring->blkif, operation) != 0) { 1280 pr_debug("access denied: %s of [%llu,%llu] on dev=%04x\n", 1281 operation == REQ_OP_READ ? "read" : "write", 1282 preq.sector_number, 1283 preq.sector_number + preq.nr_sects, 1284 ring->blkif->vbd.pdevice); 1285 goto fail_response; 1286 } 1287 1288 /* 1289 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev 1290 * is set there. 1291 */ 1292 for (i = 0; i < nseg; i++) { 1293 if (((int)preq.sector_number|(int)seg[i].nsec) & 1294 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { 1295 pr_debug("Misaligned I/O request from domain %d\n", 1296 ring->blkif->domid); 1297 goto fail_response; 1298 } 1299 } 1300 1301 /* Wait on all outstanding I/O's and once that has been completed 1302 * issue the flush. 1303 */ 1304 if (drain) 1305 xen_blk_drain_io(pending_req->ring); 1306 1307 /* 1308 * If we have failed at this point, we need to undo the M2P override, 1309 * set gnttab_set_unmap_op on all of the grant references and perform 1310 * the hypercall to unmap the grants - that is all done in 1311 * xen_blkbk_unmap. 1312 */ 1313 if (xen_blkbk_map_seg(pending_req)) 1314 goto fail_flush; 1315 1316 /* 1317 * This corresponding xen_blkif_put is done in __end_block_io_op, or 1318 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. 1319 */ 1320 xen_blkif_get(ring->blkif); 1321 atomic_inc(&ring->inflight); 1322 1323 for (i = 0; i < nseg; i++) { 1324 while ((bio == NULL) || 1325 (bio_add_page(bio, 1326 pages[i]->page, 1327 seg[i].nsec << 9, 1328 seg[i].offset) == 0)) { 1329 bio = bio_alloc(GFP_KERNEL, bio_max_segs(nseg - i)); 1330 if (unlikely(bio == NULL)) 1331 goto fail_put_bio; 1332 1333 biolist[nbio++] = bio; 1334 bio_set_dev(bio, preq.bdev); 1335 bio->bi_private = pending_req; 1336 bio->bi_end_io = end_block_io_op; 1337 bio->bi_iter.bi_sector = preq.sector_number; 1338 bio_set_op_attrs(bio, operation, operation_flags); 1339 } 1340 1341 preq.sector_number += seg[i].nsec; 1342 } 1343 1344 /* This will be hit if the operation was a flush or discard. */ 1345 if (!bio) { 1346 BUG_ON(operation_flags != REQ_PREFLUSH); 1347 1348 bio = bio_alloc(GFP_KERNEL, 0); 1349 if (unlikely(bio == NULL)) 1350 goto fail_put_bio; 1351 1352 biolist[nbio++] = bio; 1353 bio_set_dev(bio, preq.bdev); 1354 bio->bi_private = pending_req; 1355 bio->bi_end_io = end_block_io_op; 1356 bio_set_op_attrs(bio, operation, operation_flags); 1357 } 1358 1359 atomic_set(&pending_req->pendcnt, nbio); 1360 blk_start_plug(&plug); 1361 1362 for (i = 0; i < nbio; i++) 1363 submit_bio(biolist[i]); 1364 1365 /* Let the I/Os go.. */ 1366 blk_finish_plug(&plug); 1367 1368 if (operation == REQ_OP_READ) 1369 ring->st_rd_sect += preq.nr_sects; 1370 else if (operation == REQ_OP_WRITE) 1371 ring->st_wr_sect += preq.nr_sects; 1372 1373 return 0; 1374 1375 fail_flush: 1376 xen_blkbk_unmap(ring, pending_req->segments, 1377 pending_req->nr_segs); 1378 fail_response: 1379 /* Haven't submitted any bio's yet. */ 1380 make_response(ring, req->u.rw.id, req_operation, BLKIF_RSP_ERROR); 1381 free_req(ring, pending_req); 1382 msleep(1); /* back off a bit */ 1383 return -EIO; 1384 1385 fail_put_bio: 1386 for (i = 0; i < nbio; i++) 1387 bio_put(biolist[i]); 1388 atomic_set(&pending_req->pendcnt, 1); 1389 __end_block_io_op(pending_req, BLK_STS_RESOURCE); 1390 msleep(1); /* back off a bit */ 1391 return -EIO; 1392 } 1393 1394 1395 1396 /* 1397 * Put a response on the ring on how the operation fared. 1398 */ 1399 static void make_response(struct xen_blkif_ring *ring, u64 id, 1400 unsigned short op, int st) 1401 { 1402 struct blkif_response *resp; 1403 unsigned long flags; 1404 union blkif_back_rings *blk_rings; 1405 int notify; 1406 1407 spin_lock_irqsave(&ring->blk_ring_lock, flags); 1408 blk_rings = &ring->blk_rings; 1409 /* Place on the response ring for the relevant domain. */ 1410 switch (ring->blkif->blk_protocol) { 1411 case BLKIF_PROTOCOL_NATIVE: 1412 resp = RING_GET_RESPONSE(&blk_rings->native, 1413 blk_rings->native.rsp_prod_pvt); 1414 break; 1415 case BLKIF_PROTOCOL_X86_32: 1416 resp = RING_GET_RESPONSE(&blk_rings->x86_32, 1417 blk_rings->x86_32.rsp_prod_pvt); 1418 break; 1419 case BLKIF_PROTOCOL_X86_64: 1420 resp = RING_GET_RESPONSE(&blk_rings->x86_64, 1421 blk_rings->x86_64.rsp_prod_pvt); 1422 break; 1423 default: 1424 BUG(); 1425 } 1426 1427 resp->id = id; 1428 resp->operation = op; 1429 resp->status = st; 1430 1431 blk_rings->common.rsp_prod_pvt++; 1432 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); 1433 spin_unlock_irqrestore(&ring->blk_ring_lock, flags); 1434 if (notify) 1435 notify_remote_via_irq(ring->irq); 1436 } 1437 1438 static int __init xen_blkif_init(void) 1439 { 1440 int rc = 0; 1441 1442 if (!xen_domain()) 1443 return -ENODEV; 1444 1445 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 1446 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 1447 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 1448 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 1449 } 1450 1451 if (xenblk_max_queues == 0) 1452 xenblk_max_queues = num_online_cpus(); 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 static void __exit xen_blkif_fini(void) 1469 { 1470 xen_blkif_xenbus_fini(); 1471 xen_blkif_interface_fini(); 1472 } 1473 1474 module_exit(xen_blkif_fini); 1475 1476 MODULE_LICENSE("Dual BSD/GPL"); 1477 MODULE_ALIAS("xen-backend:vbd"); 1478