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 "common.h" 50 51 /* 52 * These are rather arbitrary. They are fairly large because adjacent requests 53 * pulled from a communication ring are quite likely to end up being part of 54 * the same scatter/gather request at the disc. 55 * 56 * ** TRY INCREASING 'xen_blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW ** 57 * 58 * This will increase the chances of being able to write whole tracks. 59 * 64 should be enough to keep us competitive with Linux. 60 */ 61 static int xen_blkif_reqs = 64; 62 module_param_named(reqs, xen_blkif_reqs, int, 0); 63 MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate"); 64 65 /* Run-time switchable: /sys/module/blkback/parameters/ */ 66 static unsigned int log_stats; 67 module_param(log_stats, int, 0644); 68 69 /* 70 * Each outstanding request that we've passed to the lower device layers has a 71 * 'pending_req' allocated to it. Each buffer_head that completes decrements 72 * the pendcnt towards zero. When it hits zero, the specified domain has a 73 * response queued for it, with the saved 'id' passed back. 74 */ 75 struct pending_req { 76 struct xen_blkif *blkif; 77 u64 id; 78 int nr_pages; 79 atomic_t pendcnt; 80 unsigned short operation; 81 int status; 82 struct list_head free_list; 83 DECLARE_BITMAP(unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST); 84 }; 85 86 #define BLKBACK_INVALID_HANDLE (~0) 87 88 struct xen_blkbk { 89 struct pending_req *pending_reqs; 90 /* List of all 'pending_req' available */ 91 struct list_head pending_free; 92 /* And its spinlock. */ 93 spinlock_t pending_free_lock; 94 wait_queue_head_t pending_free_wq; 95 /* The list of all pages that are available. */ 96 struct page **pending_pages; 97 /* And the grant handles that are available. */ 98 grant_handle_t *pending_grant_handles; 99 }; 100 101 static struct xen_blkbk *blkbk; 102 103 /* 104 * Maximum number of grant pages that can be mapped in blkback. 105 * BLKIF_MAX_SEGMENTS_PER_REQUEST * RING_SIZE is the maximum number of 106 * pages that blkback will persistently map. 107 * Currently, this is: 108 * RING_SIZE = 32 (for all known ring types) 109 * BLKIF_MAX_SEGMENTS_PER_REQUEST = 11 110 * sizeof(struct persistent_gnt) = 48 111 * So the maximum memory used to store the grants is: 112 * 32 * 11 * 48 = 16896 bytes 113 */ 114 static inline unsigned int max_mapped_grant_pages(enum blkif_protocol protocol) 115 { 116 switch (protocol) { 117 case BLKIF_PROTOCOL_NATIVE: 118 return __CONST_RING_SIZE(blkif, PAGE_SIZE) * 119 BLKIF_MAX_SEGMENTS_PER_REQUEST; 120 case BLKIF_PROTOCOL_X86_32: 121 return __CONST_RING_SIZE(blkif_x86_32, PAGE_SIZE) * 122 BLKIF_MAX_SEGMENTS_PER_REQUEST; 123 case BLKIF_PROTOCOL_X86_64: 124 return __CONST_RING_SIZE(blkif_x86_64, PAGE_SIZE) * 125 BLKIF_MAX_SEGMENTS_PER_REQUEST; 126 default: 127 BUG(); 128 } 129 return 0; 130 } 131 132 133 /* 134 * Little helpful macro to figure out the index and virtual address of the 135 * pending_pages[..]. For each 'pending_req' we have have up to 136 * BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through 137 * 10 and would index in the pending_pages[..]. 138 */ 139 static inline int vaddr_pagenr(struct pending_req *req, int seg) 140 { 141 return (req - blkbk->pending_reqs) * 142 BLKIF_MAX_SEGMENTS_PER_REQUEST + seg; 143 } 144 145 #define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)] 146 147 static inline unsigned long vaddr(struct pending_req *req, int seg) 148 { 149 unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg)); 150 return (unsigned long)pfn_to_kaddr(pfn); 151 } 152 153 #define pending_handle(_req, _seg) \ 154 (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)]) 155 156 157 static int do_block_io_op(struct xen_blkif *blkif); 158 static int dispatch_rw_block_io(struct xen_blkif *blkif, 159 struct blkif_request *req, 160 struct pending_req *pending_req); 161 static void make_response(struct xen_blkif *blkif, u64 id, 162 unsigned short op, int st); 163 164 #define foreach_grant_safe(pos, n, rbtree, node) \ 165 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \ 166 (n) = rb_next(&(pos)->node); \ 167 &(pos)->node != NULL; \ 168 (pos) = container_of(n, typeof(*(pos)), node), \ 169 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL) 170 171 172 static void add_persistent_gnt(struct rb_root *root, 173 struct persistent_gnt *persistent_gnt) 174 { 175 struct rb_node **new = &(root->rb_node), *parent = NULL; 176 struct persistent_gnt *this; 177 178 /* Figure out where to put new node */ 179 while (*new) { 180 this = container_of(*new, struct persistent_gnt, node); 181 182 parent = *new; 183 if (persistent_gnt->gnt < this->gnt) 184 new = &((*new)->rb_left); 185 else if (persistent_gnt->gnt > this->gnt) 186 new = &((*new)->rb_right); 187 else { 188 pr_alert(DRV_PFX " trying to add a gref that's already in the tree\n"); 189 BUG(); 190 } 191 } 192 193 /* Add new node and rebalance tree. */ 194 rb_link_node(&(persistent_gnt->node), parent, new); 195 rb_insert_color(&(persistent_gnt->node), root); 196 } 197 198 static struct persistent_gnt *get_persistent_gnt(struct rb_root *root, 199 grant_ref_t gref) 200 { 201 struct persistent_gnt *data; 202 struct rb_node *node = root->rb_node; 203 204 while (node) { 205 data = container_of(node, struct persistent_gnt, node); 206 207 if (gref < data->gnt) 208 node = node->rb_left; 209 else if (gref > data->gnt) 210 node = node->rb_right; 211 else 212 return data; 213 } 214 return NULL; 215 } 216 217 static void free_persistent_gnts(struct rb_root *root, unsigned int num) 218 { 219 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 220 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 221 struct persistent_gnt *persistent_gnt; 222 struct rb_node *n; 223 int ret = 0; 224 int segs_to_unmap = 0; 225 226 foreach_grant_safe(persistent_gnt, n, root, node) { 227 BUG_ON(persistent_gnt->handle == 228 BLKBACK_INVALID_HANDLE); 229 gnttab_set_unmap_op(&unmap[segs_to_unmap], 230 (unsigned long) pfn_to_kaddr(page_to_pfn( 231 persistent_gnt->page)), 232 GNTMAP_host_map, 233 persistent_gnt->handle); 234 235 pages[segs_to_unmap] = persistent_gnt->page; 236 237 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST || 238 !rb_next(&persistent_gnt->node)) { 239 ret = gnttab_unmap_refs(unmap, NULL, pages, 240 segs_to_unmap); 241 BUG_ON(ret); 242 segs_to_unmap = 0; 243 } 244 245 rb_erase(&persistent_gnt->node, root); 246 kfree(persistent_gnt); 247 num--; 248 } 249 BUG_ON(num != 0); 250 } 251 252 /* 253 * Retrieve from the 'pending_reqs' a free pending_req structure to be used. 254 */ 255 static struct pending_req *alloc_req(void) 256 { 257 struct pending_req *req = NULL; 258 unsigned long flags; 259 260 spin_lock_irqsave(&blkbk->pending_free_lock, flags); 261 if (!list_empty(&blkbk->pending_free)) { 262 req = list_entry(blkbk->pending_free.next, struct pending_req, 263 free_list); 264 list_del(&req->free_list); 265 } 266 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); 267 return req; 268 } 269 270 /* 271 * Return the 'pending_req' structure back to the freepool. We also 272 * wake up the thread if it was waiting for a free page. 273 */ 274 static void free_req(struct pending_req *req) 275 { 276 unsigned long flags; 277 int was_empty; 278 279 spin_lock_irqsave(&blkbk->pending_free_lock, flags); 280 was_empty = list_empty(&blkbk->pending_free); 281 list_add(&req->free_list, &blkbk->pending_free); 282 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); 283 if (was_empty) 284 wake_up(&blkbk->pending_free_wq); 285 } 286 287 /* 288 * Routines for managing virtual block devices (vbds). 289 */ 290 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, 291 int operation) 292 { 293 struct xen_vbd *vbd = &blkif->vbd; 294 int rc = -EACCES; 295 296 if ((operation != READ) && vbd->readonly) 297 goto out; 298 299 if (likely(req->nr_sects)) { 300 blkif_sector_t end = req->sector_number + req->nr_sects; 301 302 if (unlikely(end < req->sector_number)) 303 goto out; 304 if (unlikely(end > vbd_sz(vbd))) 305 goto out; 306 } 307 308 req->dev = vbd->pdevice; 309 req->bdev = vbd->bdev; 310 rc = 0; 311 312 out: 313 return rc; 314 } 315 316 static void xen_vbd_resize(struct xen_blkif *blkif) 317 { 318 struct xen_vbd *vbd = &blkif->vbd; 319 struct xenbus_transaction xbt; 320 int err; 321 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); 322 unsigned long long new_size = vbd_sz(vbd); 323 324 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n", 325 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); 326 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size); 327 vbd->size = new_size; 328 again: 329 err = xenbus_transaction_start(&xbt); 330 if (err) { 331 pr_warn(DRV_PFX "Error starting transaction"); 332 return; 333 } 334 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 335 (unsigned long long)vbd_sz(vbd)); 336 if (err) { 337 pr_warn(DRV_PFX "Error writing new size"); 338 goto abort; 339 } 340 /* 341 * Write the current state; we will use this to synchronize 342 * the front-end. If the current state is "connected" the 343 * front-end will get the new size information online. 344 */ 345 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); 346 if (err) { 347 pr_warn(DRV_PFX "Error writing the state"); 348 goto abort; 349 } 350 351 err = xenbus_transaction_end(xbt, 0); 352 if (err == -EAGAIN) 353 goto again; 354 if (err) 355 pr_warn(DRV_PFX "Error ending transaction"); 356 return; 357 abort: 358 xenbus_transaction_end(xbt, 1); 359 } 360 361 /* 362 * Notification from the guest OS. 363 */ 364 static void blkif_notify_work(struct xen_blkif *blkif) 365 { 366 blkif->waiting_reqs = 1; 367 wake_up(&blkif->wq); 368 } 369 370 irqreturn_t xen_blkif_be_int(int irq, void *dev_id) 371 { 372 blkif_notify_work(dev_id); 373 return IRQ_HANDLED; 374 } 375 376 /* 377 * SCHEDULER FUNCTIONS 378 */ 379 380 static void print_stats(struct xen_blkif *blkif) 381 { 382 pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d" 383 " | ds %4d\n", 384 current->comm, blkif->st_oo_req, 385 blkif->st_rd_req, blkif->st_wr_req, 386 blkif->st_f_req, blkif->st_ds_req); 387 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); 388 blkif->st_rd_req = 0; 389 blkif->st_wr_req = 0; 390 blkif->st_oo_req = 0; 391 blkif->st_ds_req = 0; 392 } 393 394 int xen_blkif_schedule(void *arg) 395 { 396 struct xen_blkif *blkif = arg; 397 struct xen_vbd *vbd = &blkif->vbd; 398 399 xen_blkif_get(blkif); 400 401 while (!kthread_should_stop()) { 402 if (try_to_freeze()) 403 continue; 404 if (unlikely(vbd->size != vbd_sz(vbd))) 405 xen_vbd_resize(blkif); 406 407 wait_event_interruptible( 408 blkif->wq, 409 blkif->waiting_reqs || kthread_should_stop()); 410 wait_event_interruptible( 411 blkbk->pending_free_wq, 412 !list_empty(&blkbk->pending_free) || 413 kthread_should_stop()); 414 415 blkif->waiting_reqs = 0; 416 smp_mb(); /* clear flag *before* checking for work */ 417 418 if (do_block_io_op(blkif)) 419 blkif->waiting_reqs = 1; 420 421 if (log_stats && time_after(jiffies, blkif->st_print)) 422 print_stats(blkif); 423 } 424 425 /* Free all persistent grant pages */ 426 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts)) 427 free_persistent_gnts(&blkif->persistent_gnts, 428 blkif->persistent_gnt_c); 429 430 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); 431 blkif->persistent_gnt_c = 0; 432 433 if (log_stats) 434 print_stats(blkif); 435 436 blkif->xenblkd = NULL; 437 xen_blkif_put(blkif); 438 439 return 0; 440 } 441 442 struct seg_buf { 443 unsigned long buf; 444 unsigned int nsec; 445 }; 446 /* 447 * Unmap the grant references, and also remove the M2P over-rides 448 * used in the 'pending_req'. 449 */ 450 static void xen_blkbk_unmap(struct pending_req *req) 451 { 452 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 453 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 454 unsigned int i, invcount = 0; 455 grant_handle_t handle; 456 int ret; 457 458 for (i = 0; i < req->nr_pages; i++) { 459 if (!test_bit(i, req->unmap_seg)) 460 continue; 461 handle = pending_handle(req, i); 462 if (handle == BLKBACK_INVALID_HANDLE) 463 continue; 464 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i), 465 GNTMAP_host_map, handle); 466 pending_handle(req, i) = BLKBACK_INVALID_HANDLE; 467 pages[invcount] = virt_to_page(vaddr(req, i)); 468 invcount++; 469 } 470 471 ret = gnttab_unmap_refs(unmap, NULL, pages, invcount); 472 BUG_ON(ret); 473 } 474 475 static int xen_blkbk_map(struct blkif_request *req, 476 struct pending_req *pending_req, 477 struct seg_buf seg[], 478 struct page *pages[]) 479 { 480 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 481 struct persistent_gnt *persistent_gnts[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 482 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 483 struct persistent_gnt *persistent_gnt = NULL; 484 struct xen_blkif *blkif = pending_req->blkif; 485 phys_addr_t addr = 0; 486 int i, j; 487 bool new_map; 488 int nseg = req->u.rw.nr_segments; 489 int segs_to_map = 0; 490 int ret = 0; 491 int use_persistent_gnts; 492 493 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent); 494 495 BUG_ON(blkif->persistent_gnt_c > 496 max_mapped_grant_pages(pending_req->blkif->blk_protocol)); 497 498 /* 499 * Fill out preq.nr_sects with proper amount of sectors, and setup 500 * assign map[..] with the PFN of the page in our domain with the 501 * corresponding grant reference for each page. 502 */ 503 for (i = 0; i < nseg; i++) { 504 uint32_t flags; 505 506 if (use_persistent_gnts) 507 persistent_gnt = get_persistent_gnt( 508 &blkif->persistent_gnts, 509 req->u.rw.seg[i].gref); 510 511 if (persistent_gnt) { 512 /* 513 * We are using persistent grants and 514 * the grant is already mapped 515 */ 516 new_map = false; 517 } else if (use_persistent_gnts && 518 blkif->persistent_gnt_c < 519 max_mapped_grant_pages(blkif->blk_protocol)) { 520 /* 521 * We are using persistent grants, the grant is 522 * not mapped but we have room for it 523 */ 524 new_map = true; 525 persistent_gnt = kmalloc( 526 sizeof(struct persistent_gnt), 527 GFP_KERNEL); 528 if (!persistent_gnt) 529 return -ENOMEM; 530 persistent_gnt->page = alloc_page(GFP_KERNEL); 531 if (!persistent_gnt->page) { 532 kfree(persistent_gnt); 533 return -ENOMEM; 534 } 535 persistent_gnt->gnt = req->u.rw.seg[i].gref; 536 persistent_gnt->handle = BLKBACK_INVALID_HANDLE; 537 538 pages_to_gnt[segs_to_map] = 539 persistent_gnt->page; 540 addr = (unsigned long) pfn_to_kaddr( 541 page_to_pfn(persistent_gnt->page)); 542 543 add_persistent_gnt(&blkif->persistent_gnts, 544 persistent_gnt); 545 blkif->persistent_gnt_c++; 546 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n", 547 persistent_gnt->gnt, blkif->persistent_gnt_c, 548 max_mapped_grant_pages(blkif->blk_protocol)); 549 } else { 550 /* 551 * We are either using persistent grants and 552 * hit the maximum limit of grants mapped, 553 * or we are not using persistent grants. 554 */ 555 if (use_persistent_gnts && 556 !blkif->vbd.overflow_max_grants) { 557 blkif->vbd.overflow_max_grants = 1; 558 pr_alert(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n", 559 blkif->domid, blkif->vbd.handle); 560 } 561 new_map = true; 562 pages[i] = blkbk->pending_page(pending_req, i); 563 addr = vaddr(pending_req, i); 564 pages_to_gnt[segs_to_map] = 565 blkbk->pending_page(pending_req, i); 566 } 567 568 if (persistent_gnt) { 569 pages[i] = persistent_gnt->page; 570 persistent_gnts[i] = persistent_gnt; 571 } else { 572 persistent_gnts[i] = NULL; 573 } 574 575 if (new_map) { 576 flags = GNTMAP_host_map; 577 if (!persistent_gnt && 578 (pending_req->operation != BLKIF_OP_READ)) 579 flags |= GNTMAP_readonly; 580 gnttab_set_map_op(&map[segs_to_map++], addr, 581 flags, req->u.rw.seg[i].gref, 582 blkif->domid); 583 } 584 } 585 586 if (segs_to_map) { 587 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map); 588 BUG_ON(ret); 589 } 590 591 /* 592 * Now swizzle the MFN in our domain with the MFN from the other domain 593 * so that when we access vaddr(pending_req,i) it has the contents of 594 * the page from the other domain. 595 */ 596 bitmap_zero(pending_req->unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST); 597 for (i = 0, j = 0; i < nseg; i++) { 598 if (!persistent_gnts[i] || 599 persistent_gnts[i]->handle == BLKBACK_INVALID_HANDLE) { 600 /* This is a newly mapped grant */ 601 BUG_ON(j >= segs_to_map); 602 if (unlikely(map[j].status != 0)) { 603 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n"); 604 map[j].handle = BLKBACK_INVALID_HANDLE; 605 ret |= 1; 606 if (persistent_gnts[i]) { 607 rb_erase(&persistent_gnts[i]->node, 608 &blkif->persistent_gnts); 609 blkif->persistent_gnt_c--; 610 kfree(persistent_gnts[i]); 611 persistent_gnts[i] = NULL; 612 } 613 } 614 } 615 if (persistent_gnts[i]) { 616 if (persistent_gnts[i]->handle == 617 BLKBACK_INVALID_HANDLE) { 618 /* 619 * If this is a new persistent grant 620 * save the handler 621 */ 622 persistent_gnts[i]->handle = map[j].handle; 623 persistent_gnts[i]->dev_bus_addr = 624 map[j++].dev_bus_addr; 625 } 626 pending_handle(pending_req, i) = 627 persistent_gnts[i]->handle; 628 629 if (ret) 630 continue; 631 632 seg[i].buf = persistent_gnts[i]->dev_bus_addr | 633 (req->u.rw.seg[i].first_sect << 9); 634 } else { 635 pending_handle(pending_req, i) = map[j].handle; 636 bitmap_set(pending_req->unmap_seg, i, 1); 637 638 if (ret) { 639 j++; 640 continue; 641 } 642 643 seg[i].buf = map[j++].dev_bus_addr | 644 (req->u.rw.seg[i].first_sect << 9); 645 } 646 } 647 return ret; 648 } 649 650 static int dispatch_discard_io(struct xen_blkif *blkif, 651 struct blkif_request *req) 652 { 653 int err = 0; 654 int status = BLKIF_RSP_OKAY; 655 struct block_device *bdev = blkif->vbd.bdev; 656 unsigned long secure; 657 658 blkif->st_ds_req++; 659 660 xen_blkif_get(blkif); 661 secure = (blkif->vbd.discard_secure && 662 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? 663 BLKDEV_DISCARD_SECURE : 0; 664 665 err = blkdev_issue_discard(bdev, req->u.discard.sector_number, 666 req->u.discard.nr_sectors, 667 GFP_KERNEL, secure); 668 669 if (err == -EOPNOTSUPP) { 670 pr_debug(DRV_PFX "discard op failed, not supported\n"); 671 status = BLKIF_RSP_EOPNOTSUPP; 672 } else if (err) 673 status = BLKIF_RSP_ERROR; 674 675 make_response(blkif, req->u.discard.id, req->operation, status); 676 xen_blkif_put(blkif); 677 return err; 678 } 679 680 static void xen_blk_drain_io(struct xen_blkif *blkif) 681 { 682 atomic_set(&blkif->drain, 1); 683 do { 684 /* The initial value is one, and one refcnt taken at the 685 * start of the xen_blkif_schedule thread. */ 686 if (atomic_read(&blkif->refcnt) <= 2) 687 break; 688 wait_for_completion_interruptible_timeout( 689 &blkif->drain_complete, HZ); 690 691 if (!atomic_read(&blkif->drain)) 692 break; 693 } while (!kthread_should_stop()); 694 atomic_set(&blkif->drain, 0); 695 } 696 697 /* 698 * Completion callback on the bio's. Called as bh->b_end_io() 699 */ 700 701 static void __end_block_io_op(struct pending_req *pending_req, int error) 702 { 703 /* An error fails the entire request. */ 704 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && 705 (error == -EOPNOTSUPP)) { 706 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n"); 707 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); 708 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 709 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && 710 (error == -EOPNOTSUPP)) { 711 pr_debug(DRV_PFX "write barrier op failed, not supported\n"); 712 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0); 713 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 714 } else if (error) { 715 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation," 716 " error=%d\n", error); 717 pending_req->status = BLKIF_RSP_ERROR; 718 } 719 720 /* 721 * If all of the bio's have completed it is time to unmap 722 * the grant references associated with 'request' and provide 723 * the proper response on the ring. 724 */ 725 if (atomic_dec_and_test(&pending_req->pendcnt)) { 726 xen_blkbk_unmap(pending_req); 727 make_response(pending_req->blkif, pending_req->id, 728 pending_req->operation, pending_req->status); 729 xen_blkif_put(pending_req->blkif); 730 if (atomic_read(&pending_req->blkif->refcnt) <= 2) { 731 if (atomic_read(&pending_req->blkif->drain)) 732 complete(&pending_req->blkif->drain_complete); 733 } 734 free_req(pending_req); 735 } 736 } 737 738 /* 739 * bio callback. 740 */ 741 static void end_block_io_op(struct bio *bio, int error) 742 { 743 __end_block_io_op(bio->bi_private, error); 744 bio_put(bio); 745 } 746 747 748 749 /* 750 * Function to copy the from the ring buffer the 'struct blkif_request' 751 * (which has the sectors we want, number of them, grant references, etc), 752 * and transmute it to the block API to hand it over to the proper block disk. 753 */ 754 static int 755 __do_block_io_op(struct xen_blkif *blkif) 756 { 757 union blkif_back_rings *blk_rings = &blkif->blk_rings; 758 struct blkif_request req; 759 struct pending_req *pending_req; 760 RING_IDX rc, rp; 761 int more_to_do = 0; 762 763 rc = blk_rings->common.req_cons; 764 rp = blk_rings->common.sring->req_prod; 765 rmb(); /* Ensure we see queued requests up to 'rp'. */ 766 767 while (rc != rp) { 768 769 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) 770 break; 771 772 if (kthread_should_stop()) { 773 more_to_do = 1; 774 break; 775 } 776 777 pending_req = alloc_req(); 778 if (NULL == pending_req) { 779 blkif->st_oo_req++; 780 more_to_do = 1; 781 break; 782 } 783 784 switch (blkif->blk_protocol) { 785 case BLKIF_PROTOCOL_NATIVE: 786 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); 787 break; 788 case BLKIF_PROTOCOL_X86_32: 789 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); 790 break; 791 case BLKIF_PROTOCOL_X86_64: 792 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); 793 break; 794 default: 795 BUG(); 796 } 797 blk_rings->common.req_cons = ++rc; /* before make_response() */ 798 799 /* Apply all sanity checks to /private copy/ of request. */ 800 barrier(); 801 if (unlikely(req.operation == BLKIF_OP_DISCARD)) { 802 free_req(pending_req); 803 if (dispatch_discard_io(blkif, &req)) 804 break; 805 } else if (dispatch_rw_block_io(blkif, &req, pending_req)) 806 break; 807 808 /* Yield point for this unbounded loop. */ 809 cond_resched(); 810 } 811 812 return more_to_do; 813 } 814 815 static int 816 do_block_io_op(struct xen_blkif *blkif) 817 { 818 union blkif_back_rings *blk_rings = &blkif->blk_rings; 819 int more_to_do; 820 821 do { 822 more_to_do = __do_block_io_op(blkif); 823 if (more_to_do) 824 break; 825 826 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); 827 } while (more_to_do); 828 829 return more_to_do; 830 } 831 /* 832 * Transmutation of the 'struct blkif_request' to a proper 'struct bio' 833 * and call the 'submit_bio' to pass it to the underlying storage. 834 */ 835 static int dispatch_rw_block_io(struct xen_blkif *blkif, 836 struct blkif_request *req, 837 struct pending_req *pending_req) 838 { 839 struct phys_req preq; 840 struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 841 unsigned int nseg; 842 struct bio *bio = NULL; 843 struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 844 int i, nbio = 0; 845 int operation; 846 struct blk_plug plug; 847 bool drain = false; 848 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 849 850 switch (req->operation) { 851 case BLKIF_OP_READ: 852 blkif->st_rd_req++; 853 operation = READ; 854 break; 855 case BLKIF_OP_WRITE: 856 blkif->st_wr_req++; 857 operation = WRITE_ODIRECT; 858 break; 859 case BLKIF_OP_WRITE_BARRIER: 860 drain = true; 861 case BLKIF_OP_FLUSH_DISKCACHE: 862 blkif->st_f_req++; 863 operation = WRITE_FLUSH; 864 break; 865 default: 866 operation = 0; /* make gcc happy */ 867 goto fail_response; 868 break; 869 } 870 871 /* Check that the number of segments is sane. */ 872 nseg = req->u.rw.nr_segments; 873 874 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || 875 unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 876 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n", 877 nseg); 878 /* Haven't submitted any bio's yet. */ 879 goto fail_response; 880 } 881 882 preq.dev = req->u.rw.handle; 883 preq.sector_number = req->u.rw.sector_number; 884 preq.nr_sects = 0; 885 886 pending_req->blkif = blkif; 887 pending_req->id = req->u.rw.id; 888 pending_req->operation = req->operation; 889 pending_req->status = BLKIF_RSP_OKAY; 890 pending_req->nr_pages = nseg; 891 892 for (i = 0; i < nseg; i++) { 893 seg[i].nsec = req->u.rw.seg[i].last_sect - 894 req->u.rw.seg[i].first_sect + 1; 895 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || 896 (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect)) 897 goto fail_response; 898 preq.nr_sects += seg[i].nsec; 899 900 } 901 902 if (xen_vbd_translate(&preq, blkif, operation) != 0) { 903 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n", 904 operation == READ ? "read" : "write", 905 preq.sector_number, 906 preq.sector_number + preq.nr_sects, preq.dev); 907 goto fail_response; 908 } 909 910 /* 911 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev 912 * is set there. 913 */ 914 for (i = 0; i < nseg; i++) { 915 if (((int)preq.sector_number|(int)seg[i].nsec) & 916 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { 917 pr_debug(DRV_PFX "Misaligned I/O request from domain %d", 918 blkif->domid); 919 goto fail_response; 920 } 921 } 922 923 /* Wait on all outstanding I/O's and once that has been completed 924 * issue the WRITE_FLUSH. 925 */ 926 if (drain) 927 xen_blk_drain_io(pending_req->blkif); 928 929 /* 930 * If we have failed at this point, we need to undo the M2P override, 931 * set gnttab_set_unmap_op on all of the grant references and perform 932 * the hypercall to unmap the grants - that is all done in 933 * xen_blkbk_unmap. 934 */ 935 if (xen_blkbk_map(req, pending_req, seg, pages)) 936 goto fail_flush; 937 938 /* 939 * This corresponding xen_blkif_put is done in __end_block_io_op, or 940 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. 941 */ 942 xen_blkif_get(blkif); 943 944 for (i = 0; i < nseg; i++) { 945 while ((bio == NULL) || 946 (bio_add_page(bio, 947 pages[i], 948 seg[i].nsec << 9, 949 seg[i].buf & ~PAGE_MASK) == 0)) { 950 951 bio = bio_alloc(GFP_KERNEL, nseg-i); 952 if (unlikely(bio == NULL)) 953 goto fail_put_bio; 954 955 biolist[nbio++] = bio; 956 bio->bi_bdev = preq.bdev; 957 bio->bi_private = pending_req; 958 bio->bi_end_io = end_block_io_op; 959 bio->bi_sector = preq.sector_number; 960 } 961 962 preq.sector_number += seg[i].nsec; 963 } 964 965 /* This will be hit if the operation was a flush or discard. */ 966 if (!bio) { 967 BUG_ON(operation != WRITE_FLUSH); 968 969 bio = bio_alloc(GFP_KERNEL, 0); 970 if (unlikely(bio == NULL)) 971 goto fail_put_bio; 972 973 biolist[nbio++] = bio; 974 bio->bi_bdev = preq.bdev; 975 bio->bi_private = pending_req; 976 bio->bi_end_io = end_block_io_op; 977 } 978 979 /* 980 * We set it one so that the last submit_bio does not have to call 981 * atomic_inc. 982 */ 983 atomic_set(&pending_req->pendcnt, nbio); 984 985 /* Get a reference count for the disk queue and start sending I/O */ 986 blk_start_plug(&plug); 987 988 for (i = 0; i < nbio; i++) 989 submit_bio(operation, biolist[i]); 990 991 /* Let the I/Os go.. */ 992 blk_finish_plug(&plug); 993 994 if (operation == READ) 995 blkif->st_rd_sect += preq.nr_sects; 996 else if (operation & WRITE) 997 blkif->st_wr_sect += preq.nr_sects; 998 999 return 0; 1000 1001 fail_flush: 1002 xen_blkbk_unmap(pending_req); 1003 fail_response: 1004 /* Haven't submitted any bio's yet. */ 1005 make_response(blkif, req->u.rw.id, req->operation, BLKIF_RSP_ERROR); 1006 free_req(pending_req); 1007 msleep(1); /* back off a bit */ 1008 return -EIO; 1009 1010 fail_put_bio: 1011 for (i = 0; i < nbio; i++) 1012 bio_put(biolist[i]); 1013 __end_block_io_op(pending_req, -EINVAL); 1014 msleep(1); /* back off a bit */ 1015 return -EIO; 1016 } 1017 1018 1019 1020 /* 1021 * Put a response on the ring on how the operation fared. 1022 */ 1023 static void make_response(struct xen_blkif *blkif, u64 id, 1024 unsigned short op, int st) 1025 { 1026 struct blkif_response resp; 1027 unsigned long flags; 1028 union blkif_back_rings *blk_rings = &blkif->blk_rings; 1029 int notify; 1030 1031 resp.id = id; 1032 resp.operation = op; 1033 resp.status = st; 1034 1035 spin_lock_irqsave(&blkif->blk_ring_lock, flags); 1036 /* Place on the response ring for the relevant domain. */ 1037 switch (blkif->blk_protocol) { 1038 case BLKIF_PROTOCOL_NATIVE: 1039 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), 1040 &resp, sizeof(resp)); 1041 break; 1042 case BLKIF_PROTOCOL_X86_32: 1043 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), 1044 &resp, sizeof(resp)); 1045 break; 1046 case BLKIF_PROTOCOL_X86_64: 1047 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), 1048 &resp, sizeof(resp)); 1049 break; 1050 default: 1051 BUG(); 1052 } 1053 blk_rings->common.rsp_prod_pvt++; 1054 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); 1055 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); 1056 if (notify) 1057 notify_remote_via_irq(blkif->irq); 1058 } 1059 1060 static int __init xen_blkif_init(void) 1061 { 1062 int i, mmap_pages; 1063 int rc = 0; 1064 1065 if (!xen_domain()) 1066 return -ENODEV; 1067 1068 blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL); 1069 if (!blkbk) { 1070 pr_alert(DRV_PFX "%s: out of memory!\n", __func__); 1071 return -ENOMEM; 1072 } 1073 1074 mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST; 1075 1076 blkbk->pending_reqs = kzalloc(sizeof(blkbk->pending_reqs[0]) * 1077 xen_blkif_reqs, GFP_KERNEL); 1078 blkbk->pending_grant_handles = kmalloc(sizeof(blkbk->pending_grant_handles[0]) * 1079 mmap_pages, GFP_KERNEL); 1080 blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) * 1081 mmap_pages, GFP_KERNEL); 1082 1083 if (!blkbk->pending_reqs || !blkbk->pending_grant_handles || 1084 !blkbk->pending_pages) { 1085 rc = -ENOMEM; 1086 goto out_of_memory; 1087 } 1088 1089 for (i = 0; i < mmap_pages; i++) { 1090 blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE; 1091 blkbk->pending_pages[i] = alloc_page(GFP_KERNEL); 1092 if (blkbk->pending_pages[i] == NULL) { 1093 rc = -ENOMEM; 1094 goto out_of_memory; 1095 } 1096 } 1097 rc = xen_blkif_interface_init(); 1098 if (rc) 1099 goto failed_init; 1100 1101 INIT_LIST_HEAD(&blkbk->pending_free); 1102 spin_lock_init(&blkbk->pending_free_lock); 1103 init_waitqueue_head(&blkbk->pending_free_wq); 1104 1105 for (i = 0; i < xen_blkif_reqs; i++) 1106 list_add_tail(&blkbk->pending_reqs[i].free_list, 1107 &blkbk->pending_free); 1108 1109 rc = xen_blkif_xenbus_init(); 1110 if (rc) 1111 goto failed_init; 1112 1113 return 0; 1114 1115 out_of_memory: 1116 pr_alert(DRV_PFX "%s: out of memory\n", __func__); 1117 failed_init: 1118 kfree(blkbk->pending_reqs); 1119 kfree(blkbk->pending_grant_handles); 1120 if (blkbk->pending_pages) { 1121 for (i = 0; i < mmap_pages; i++) { 1122 if (blkbk->pending_pages[i]) 1123 __free_page(blkbk->pending_pages[i]); 1124 } 1125 kfree(blkbk->pending_pages); 1126 } 1127 kfree(blkbk); 1128 blkbk = NULL; 1129 return rc; 1130 } 1131 1132 module_init(xen_blkif_init); 1133 1134 MODULE_LICENSE("Dual BSD/GPL"); 1135 MODULE_ALIAS("xen-backend:vbd"); 1136