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 43 #include <xen/events.h> 44 #include <xen/page.h> 45 #include <xen/xen.h> 46 #include <asm/xen/hypervisor.h> 47 #include <asm/xen/hypercall.h> 48 #include "common.h" 49 50 /* 51 * These are rather arbitrary. They are fairly large because adjacent requests 52 * pulled from a communication ring are quite likely to end up being part of 53 * the same scatter/gather request at the disc. 54 * 55 * ** TRY INCREASING 'xen_blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW ** 56 * 57 * This will increase the chances of being able to write whole tracks. 58 * 64 should be enough to keep us competitive with Linux. 59 */ 60 static int xen_blkif_reqs = 64; 61 module_param_named(reqs, xen_blkif_reqs, int, 0); 62 MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate"); 63 64 /* Run-time switchable: /sys/module/blkback/parameters/ */ 65 static unsigned int log_stats; 66 module_param(log_stats, int, 0644); 67 68 /* 69 * Each outstanding request that we've passed to the lower device layers has a 70 * 'pending_req' allocated to it. Each buffer_head that completes decrements 71 * the pendcnt towards zero. When it hits zero, the specified domain has a 72 * response queued for it, with the saved 'id' passed back. 73 */ 74 struct pending_req { 75 struct xen_blkif *blkif; 76 u64 id; 77 int nr_pages; 78 atomic_t pendcnt; 79 unsigned short operation; 80 int status; 81 struct list_head free_list; 82 }; 83 84 #define BLKBACK_INVALID_HANDLE (~0) 85 86 struct xen_blkbk { 87 struct pending_req *pending_reqs; 88 /* List of all 'pending_req' available */ 89 struct list_head pending_free; 90 /* And its spinlock. */ 91 spinlock_t pending_free_lock; 92 wait_queue_head_t pending_free_wq; 93 /* The list of all pages that are available. */ 94 struct page **pending_pages; 95 /* And the grant handles that are available. */ 96 grant_handle_t *pending_grant_handles; 97 }; 98 99 static struct xen_blkbk *blkbk; 100 101 /* 102 * Little helpful macro to figure out the index and virtual address of the 103 * pending_pages[..]. For each 'pending_req' we have have up to 104 * BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through 105 * 10 and would index in the pending_pages[..]. 106 */ 107 static inline int vaddr_pagenr(struct pending_req *req, int seg) 108 { 109 return (req - blkbk->pending_reqs) * 110 BLKIF_MAX_SEGMENTS_PER_REQUEST + seg; 111 } 112 113 #define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)] 114 115 static inline unsigned long vaddr(struct pending_req *req, int seg) 116 { 117 unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg)); 118 return (unsigned long)pfn_to_kaddr(pfn); 119 } 120 121 #define pending_handle(_req, _seg) \ 122 (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)]) 123 124 125 static int do_block_io_op(struct xen_blkif *blkif); 126 static int dispatch_rw_block_io(struct xen_blkif *blkif, 127 struct blkif_request *req, 128 struct pending_req *pending_req); 129 static void make_response(struct xen_blkif *blkif, u64 id, 130 unsigned short op, int st); 131 132 /* 133 * Retrieve from the 'pending_reqs' a free pending_req structure to be used. 134 */ 135 static struct pending_req *alloc_req(void) 136 { 137 struct pending_req *req = NULL; 138 unsigned long flags; 139 140 spin_lock_irqsave(&blkbk->pending_free_lock, flags); 141 if (!list_empty(&blkbk->pending_free)) { 142 req = list_entry(blkbk->pending_free.next, struct pending_req, 143 free_list); 144 list_del(&req->free_list); 145 } 146 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); 147 return req; 148 } 149 150 /* 151 * Return the 'pending_req' structure back to the freepool. We also 152 * wake up the thread if it was waiting for a free page. 153 */ 154 static void free_req(struct pending_req *req) 155 { 156 unsigned long flags; 157 int was_empty; 158 159 spin_lock_irqsave(&blkbk->pending_free_lock, flags); 160 was_empty = list_empty(&blkbk->pending_free); 161 list_add(&req->free_list, &blkbk->pending_free); 162 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); 163 if (was_empty) 164 wake_up(&blkbk->pending_free_wq); 165 } 166 167 /* 168 * Routines for managing virtual block devices (vbds). 169 */ 170 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, 171 int operation) 172 { 173 struct xen_vbd *vbd = &blkif->vbd; 174 int rc = -EACCES; 175 176 if ((operation != READ) && vbd->readonly) 177 goto out; 178 179 if (likely(req->nr_sects)) { 180 blkif_sector_t end = req->sector_number + req->nr_sects; 181 182 if (unlikely(end < req->sector_number)) 183 goto out; 184 if (unlikely(end > vbd_sz(vbd))) 185 goto out; 186 } 187 188 req->dev = vbd->pdevice; 189 req->bdev = vbd->bdev; 190 rc = 0; 191 192 out: 193 return rc; 194 } 195 196 static void xen_vbd_resize(struct xen_blkif *blkif) 197 { 198 struct xen_vbd *vbd = &blkif->vbd; 199 struct xenbus_transaction xbt; 200 int err; 201 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); 202 unsigned long long new_size = vbd_sz(vbd); 203 204 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n", 205 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); 206 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size); 207 vbd->size = new_size; 208 again: 209 err = xenbus_transaction_start(&xbt); 210 if (err) { 211 pr_warn(DRV_PFX "Error starting transaction"); 212 return; 213 } 214 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 215 (unsigned long long)vbd_sz(vbd)); 216 if (err) { 217 pr_warn(DRV_PFX "Error writing new size"); 218 goto abort; 219 } 220 /* 221 * Write the current state; we will use this to synchronize 222 * the front-end. If the current state is "connected" the 223 * front-end will get the new size information online. 224 */ 225 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); 226 if (err) { 227 pr_warn(DRV_PFX "Error writing the state"); 228 goto abort; 229 } 230 231 err = xenbus_transaction_end(xbt, 0); 232 if (err == -EAGAIN) 233 goto again; 234 if (err) 235 pr_warn(DRV_PFX "Error ending transaction"); 236 return; 237 abort: 238 xenbus_transaction_end(xbt, 1); 239 } 240 241 /* 242 * Notification from the guest OS. 243 */ 244 static void blkif_notify_work(struct xen_blkif *blkif) 245 { 246 blkif->waiting_reqs = 1; 247 wake_up(&blkif->wq); 248 } 249 250 irqreturn_t xen_blkif_be_int(int irq, void *dev_id) 251 { 252 blkif_notify_work(dev_id); 253 return IRQ_HANDLED; 254 } 255 256 /* 257 * SCHEDULER FUNCTIONS 258 */ 259 260 static void print_stats(struct xen_blkif *blkif) 261 { 262 pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d" 263 " | ds %4d\n", 264 current->comm, blkif->st_oo_req, 265 blkif->st_rd_req, blkif->st_wr_req, 266 blkif->st_f_req, blkif->st_ds_req); 267 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); 268 blkif->st_rd_req = 0; 269 blkif->st_wr_req = 0; 270 blkif->st_oo_req = 0; 271 blkif->st_ds_req = 0; 272 } 273 274 int xen_blkif_schedule(void *arg) 275 { 276 struct xen_blkif *blkif = arg; 277 struct xen_vbd *vbd = &blkif->vbd; 278 279 xen_blkif_get(blkif); 280 281 while (!kthread_should_stop()) { 282 if (try_to_freeze()) 283 continue; 284 if (unlikely(vbd->size != vbd_sz(vbd))) 285 xen_vbd_resize(blkif); 286 287 wait_event_interruptible( 288 blkif->wq, 289 blkif->waiting_reqs || kthread_should_stop()); 290 wait_event_interruptible( 291 blkbk->pending_free_wq, 292 !list_empty(&blkbk->pending_free) || 293 kthread_should_stop()); 294 295 blkif->waiting_reqs = 0; 296 smp_mb(); /* clear flag *before* checking for work */ 297 298 if (do_block_io_op(blkif)) 299 blkif->waiting_reqs = 1; 300 301 if (log_stats && time_after(jiffies, blkif->st_print)) 302 print_stats(blkif); 303 } 304 305 if (log_stats) 306 print_stats(blkif); 307 308 blkif->xenblkd = NULL; 309 xen_blkif_put(blkif); 310 311 return 0; 312 } 313 314 struct seg_buf { 315 unsigned long buf; 316 unsigned int nsec; 317 }; 318 /* 319 * Unmap the grant references, and also remove the M2P over-rides 320 * used in the 'pending_req'. 321 */ 322 static void xen_blkbk_unmap(struct pending_req *req) 323 { 324 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 325 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 326 unsigned int i, invcount = 0; 327 grant_handle_t handle; 328 int ret; 329 330 for (i = 0; i < req->nr_pages; i++) { 331 handle = pending_handle(req, i); 332 if (handle == BLKBACK_INVALID_HANDLE) 333 continue; 334 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i), 335 GNTMAP_host_map, handle); 336 pending_handle(req, i) = BLKBACK_INVALID_HANDLE; 337 pages[invcount] = virt_to_page(vaddr(req, i)); 338 invcount++; 339 } 340 341 ret = gnttab_unmap_refs(unmap, NULL, pages, invcount); 342 BUG_ON(ret); 343 } 344 345 static int xen_blkbk_map(struct blkif_request *req, 346 struct pending_req *pending_req, 347 struct seg_buf seg[]) 348 { 349 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 350 int i; 351 int nseg = req->u.rw.nr_segments; 352 int ret = 0; 353 354 /* 355 * Fill out preq.nr_sects with proper amount of sectors, and setup 356 * assign map[..] with the PFN of the page in our domain with the 357 * corresponding grant reference for each page. 358 */ 359 for (i = 0; i < nseg; i++) { 360 uint32_t flags; 361 362 flags = GNTMAP_host_map; 363 if (pending_req->operation != BLKIF_OP_READ) 364 flags |= GNTMAP_readonly; 365 gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags, 366 req->u.rw.seg[i].gref, 367 pending_req->blkif->domid); 368 } 369 370 ret = gnttab_map_refs(map, NULL, &blkbk->pending_page(pending_req, 0), nseg); 371 BUG_ON(ret); 372 373 /* 374 * Now swizzle the MFN in our domain with the MFN from the other domain 375 * so that when we access vaddr(pending_req,i) it has the contents of 376 * the page from the other domain. 377 */ 378 for (i = 0; i < nseg; i++) { 379 if (unlikely(map[i].status != 0)) { 380 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n"); 381 map[i].handle = BLKBACK_INVALID_HANDLE; 382 ret |= 1; 383 } 384 385 pending_handle(pending_req, i) = map[i].handle; 386 387 if (ret) 388 continue; 389 390 seg[i].buf = map[i].dev_bus_addr | 391 (req->u.rw.seg[i].first_sect << 9); 392 } 393 return ret; 394 } 395 396 static int dispatch_discard_io(struct xen_blkif *blkif, 397 struct blkif_request *req) 398 { 399 int err = 0; 400 int status = BLKIF_RSP_OKAY; 401 struct block_device *bdev = blkif->vbd.bdev; 402 unsigned long secure; 403 404 blkif->st_ds_req++; 405 406 xen_blkif_get(blkif); 407 secure = (blkif->vbd.discard_secure && 408 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? 409 BLKDEV_DISCARD_SECURE : 0; 410 411 err = blkdev_issue_discard(bdev, req->u.discard.sector_number, 412 req->u.discard.nr_sectors, 413 GFP_KERNEL, secure); 414 415 if (err == -EOPNOTSUPP) { 416 pr_debug(DRV_PFX "discard op failed, not supported\n"); 417 status = BLKIF_RSP_EOPNOTSUPP; 418 } else if (err) 419 status = BLKIF_RSP_ERROR; 420 421 make_response(blkif, req->u.discard.id, req->operation, status); 422 xen_blkif_put(blkif); 423 return err; 424 } 425 426 static void xen_blk_drain_io(struct xen_blkif *blkif) 427 { 428 atomic_set(&blkif->drain, 1); 429 do { 430 /* The initial value is one, and one refcnt taken at the 431 * start of the xen_blkif_schedule thread. */ 432 if (atomic_read(&blkif->refcnt) <= 2) 433 break; 434 wait_for_completion_interruptible_timeout( 435 &blkif->drain_complete, HZ); 436 437 if (!atomic_read(&blkif->drain)) 438 break; 439 } while (!kthread_should_stop()); 440 atomic_set(&blkif->drain, 0); 441 } 442 443 /* 444 * Completion callback on the bio's. Called as bh->b_end_io() 445 */ 446 447 static void __end_block_io_op(struct pending_req *pending_req, int error) 448 { 449 /* An error fails the entire request. */ 450 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && 451 (error == -EOPNOTSUPP)) { 452 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n"); 453 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); 454 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 455 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && 456 (error == -EOPNOTSUPP)) { 457 pr_debug(DRV_PFX "write barrier op failed, not supported\n"); 458 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0); 459 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 460 } else if (error) { 461 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation," 462 " error=%d\n", error); 463 pending_req->status = BLKIF_RSP_ERROR; 464 } 465 466 /* 467 * If all of the bio's have completed it is time to unmap 468 * the grant references associated with 'request' and provide 469 * the proper response on the ring. 470 */ 471 if (atomic_dec_and_test(&pending_req->pendcnt)) { 472 xen_blkbk_unmap(pending_req); 473 make_response(pending_req->blkif, pending_req->id, 474 pending_req->operation, pending_req->status); 475 xen_blkif_put(pending_req->blkif); 476 if (atomic_read(&pending_req->blkif->refcnt) <= 2) { 477 if (atomic_read(&pending_req->blkif->drain)) 478 complete(&pending_req->blkif->drain_complete); 479 } 480 free_req(pending_req); 481 } 482 } 483 484 /* 485 * bio callback. 486 */ 487 static void end_block_io_op(struct bio *bio, int error) 488 { 489 __end_block_io_op(bio->bi_private, error); 490 bio_put(bio); 491 } 492 493 494 495 /* 496 * Function to copy the from the ring buffer the 'struct blkif_request' 497 * (which has the sectors we want, number of them, grant references, etc), 498 * and transmute it to the block API to hand it over to the proper block disk. 499 */ 500 static int 501 __do_block_io_op(struct xen_blkif *blkif) 502 { 503 union blkif_back_rings *blk_rings = &blkif->blk_rings; 504 struct blkif_request req; 505 struct pending_req *pending_req; 506 RING_IDX rc, rp; 507 int more_to_do = 0; 508 509 rc = blk_rings->common.req_cons; 510 rp = blk_rings->common.sring->req_prod; 511 rmb(); /* Ensure we see queued requests up to 'rp'. */ 512 513 while (rc != rp) { 514 515 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) 516 break; 517 518 if (kthread_should_stop()) { 519 more_to_do = 1; 520 break; 521 } 522 523 pending_req = alloc_req(); 524 if (NULL == pending_req) { 525 blkif->st_oo_req++; 526 more_to_do = 1; 527 break; 528 } 529 530 switch (blkif->blk_protocol) { 531 case BLKIF_PROTOCOL_NATIVE: 532 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); 533 break; 534 case BLKIF_PROTOCOL_X86_32: 535 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); 536 break; 537 case BLKIF_PROTOCOL_X86_64: 538 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); 539 break; 540 default: 541 BUG(); 542 } 543 blk_rings->common.req_cons = ++rc; /* before make_response() */ 544 545 /* Apply all sanity checks to /private copy/ of request. */ 546 barrier(); 547 if (unlikely(req.operation == BLKIF_OP_DISCARD)) { 548 free_req(pending_req); 549 if (dispatch_discard_io(blkif, &req)) 550 break; 551 } else if (dispatch_rw_block_io(blkif, &req, pending_req)) 552 break; 553 554 /* Yield point for this unbounded loop. */ 555 cond_resched(); 556 } 557 558 return more_to_do; 559 } 560 561 static int 562 do_block_io_op(struct xen_blkif *blkif) 563 { 564 union blkif_back_rings *blk_rings = &blkif->blk_rings; 565 int more_to_do; 566 567 do { 568 more_to_do = __do_block_io_op(blkif); 569 if (more_to_do) 570 break; 571 572 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); 573 } while (more_to_do); 574 575 return more_to_do; 576 } 577 /* 578 * Transmutation of the 'struct blkif_request' to a proper 'struct bio' 579 * and call the 'submit_bio' to pass it to the underlying storage. 580 */ 581 static int dispatch_rw_block_io(struct xen_blkif *blkif, 582 struct blkif_request *req, 583 struct pending_req *pending_req) 584 { 585 struct phys_req preq; 586 struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 587 unsigned int nseg; 588 struct bio *bio = NULL; 589 struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 590 int i, nbio = 0; 591 int operation; 592 struct blk_plug plug; 593 bool drain = false; 594 595 switch (req->operation) { 596 case BLKIF_OP_READ: 597 blkif->st_rd_req++; 598 operation = READ; 599 break; 600 case BLKIF_OP_WRITE: 601 blkif->st_wr_req++; 602 operation = WRITE_ODIRECT; 603 break; 604 case BLKIF_OP_WRITE_BARRIER: 605 drain = true; 606 case BLKIF_OP_FLUSH_DISKCACHE: 607 blkif->st_f_req++; 608 operation = WRITE_FLUSH; 609 break; 610 default: 611 operation = 0; /* make gcc happy */ 612 goto fail_response; 613 break; 614 } 615 616 /* Check that the number of segments is sane. */ 617 nseg = req->u.rw.nr_segments; 618 619 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || 620 unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 621 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n", 622 nseg); 623 /* Haven't submitted any bio's yet. */ 624 goto fail_response; 625 } 626 627 preq.dev = req->u.rw.handle; 628 preq.sector_number = req->u.rw.sector_number; 629 preq.nr_sects = 0; 630 631 pending_req->blkif = blkif; 632 pending_req->id = req->u.rw.id; 633 pending_req->operation = req->operation; 634 pending_req->status = BLKIF_RSP_OKAY; 635 pending_req->nr_pages = nseg; 636 637 for (i = 0; i < nseg; i++) { 638 seg[i].nsec = req->u.rw.seg[i].last_sect - 639 req->u.rw.seg[i].first_sect + 1; 640 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || 641 (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect)) 642 goto fail_response; 643 preq.nr_sects += seg[i].nsec; 644 645 } 646 647 if (xen_vbd_translate(&preq, blkif, operation) != 0) { 648 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n", 649 operation == READ ? "read" : "write", 650 preq.sector_number, 651 preq.sector_number + preq.nr_sects, preq.dev); 652 goto fail_response; 653 } 654 655 /* 656 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev 657 * is set there. 658 */ 659 for (i = 0; i < nseg; i++) { 660 if (((int)preq.sector_number|(int)seg[i].nsec) & 661 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { 662 pr_debug(DRV_PFX "Misaligned I/O request from domain %d", 663 blkif->domid); 664 goto fail_response; 665 } 666 } 667 668 /* Wait on all outstanding I/O's and once that has been completed 669 * issue the WRITE_FLUSH. 670 */ 671 if (drain) 672 xen_blk_drain_io(pending_req->blkif); 673 674 /* 675 * If we have failed at this point, we need to undo the M2P override, 676 * set gnttab_set_unmap_op on all of the grant references and perform 677 * the hypercall to unmap the grants - that is all done in 678 * xen_blkbk_unmap. 679 */ 680 if (xen_blkbk_map(req, pending_req, seg)) 681 goto fail_flush; 682 683 /* 684 * This corresponding xen_blkif_put is done in __end_block_io_op, or 685 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. 686 */ 687 xen_blkif_get(blkif); 688 689 for (i = 0; i < nseg; i++) { 690 while ((bio == NULL) || 691 (bio_add_page(bio, 692 blkbk->pending_page(pending_req, i), 693 seg[i].nsec << 9, 694 seg[i].buf & ~PAGE_MASK) == 0)) { 695 696 bio = bio_alloc(GFP_KERNEL, nseg-i); 697 if (unlikely(bio == NULL)) 698 goto fail_put_bio; 699 700 biolist[nbio++] = bio; 701 bio->bi_bdev = preq.bdev; 702 bio->bi_private = pending_req; 703 bio->bi_end_io = end_block_io_op; 704 bio->bi_sector = preq.sector_number; 705 } 706 707 preq.sector_number += seg[i].nsec; 708 } 709 710 /* This will be hit if the operation was a flush or discard. */ 711 if (!bio) { 712 BUG_ON(operation != WRITE_FLUSH); 713 714 bio = bio_alloc(GFP_KERNEL, 0); 715 if (unlikely(bio == NULL)) 716 goto fail_put_bio; 717 718 biolist[nbio++] = bio; 719 bio->bi_bdev = preq.bdev; 720 bio->bi_private = pending_req; 721 bio->bi_end_io = end_block_io_op; 722 } 723 724 /* 725 * We set it one so that the last submit_bio does not have to call 726 * atomic_inc. 727 */ 728 atomic_set(&pending_req->pendcnt, nbio); 729 730 /* Get a reference count for the disk queue and start sending I/O */ 731 blk_start_plug(&plug); 732 733 for (i = 0; i < nbio; i++) 734 submit_bio(operation, biolist[i]); 735 736 /* Let the I/Os go.. */ 737 blk_finish_plug(&plug); 738 739 if (operation == READ) 740 blkif->st_rd_sect += preq.nr_sects; 741 else if (operation & WRITE) 742 blkif->st_wr_sect += preq.nr_sects; 743 744 return 0; 745 746 fail_flush: 747 xen_blkbk_unmap(pending_req); 748 fail_response: 749 /* Haven't submitted any bio's yet. */ 750 make_response(blkif, req->u.rw.id, req->operation, BLKIF_RSP_ERROR); 751 free_req(pending_req); 752 msleep(1); /* back off a bit */ 753 return -EIO; 754 755 fail_put_bio: 756 for (i = 0; i < nbio; i++) 757 bio_put(biolist[i]); 758 __end_block_io_op(pending_req, -EINVAL); 759 msleep(1); /* back off a bit */ 760 return -EIO; 761 } 762 763 764 765 /* 766 * Put a response on the ring on how the operation fared. 767 */ 768 static void make_response(struct xen_blkif *blkif, u64 id, 769 unsigned short op, int st) 770 { 771 struct blkif_response resp; 772 unsigned long flags; 773 union blkif_back_rings *blk_rings = &blkif->blk_rings; 774 int notify; 775 776 resp.id = id; 777 resp.operation = op; 778 resp.status = st; 779 780 spin_lock_irqsave(&blkif->blk_ring_lock, flags); 781 /* Place on the response ring for the relevant domain. */ 782 switch (blkif->blk_protocol) { 783 case BLKIF_PROTOCOL_NATIVE: 784 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), 785 &resp, sizeof(resp)); 786 break; 787 case BLKIF_PROTOCOL_X86_32: 788 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), 789 &resp, sizeof(resp)); 790 break; 791 case BLKIF_PROTOCOL_X86_64: 792 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), 793 &resp, sizeof(resp)); 794 break; 795 default: 796 BUG(); 797 } 798 blk_rings->common.rsp_prod_pvt++; 799 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); 800 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); 801 if (notify) 802 notify_remote_via_irq(blkif->irq); 803 } 804 805 static int __init xen_blkif_init(void) 806 { 807 int i, mmap_pages; 808 int rc = 0; 809 810 if (!xen_domain()) 811 return -ENODEV; 812 813 blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL); 814 if (!blkbk) { 815 pr_alert(DRV_PFX "%s: out of memory!\n", __func__); 816 return -ENOMEM; 817 } 818 819 mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST; 820 821 blkbk->pending_reqs = kzalloc(sizeof(blkbk->pending_reqs[0]) * 822 xen_blkif_reqs, GFP_KERNEL); 823 blkbk->pending_grant_handles = kmalloc(sizeof(blkbk->pending_grant_handles[0]) * 824 mmap_pages, GFP_KERNEL); 825 blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) * 826 mmap_pages, GFP_KERNEL); 827 828 if (!blkbk->pending_reqs || !blkbk->pending_grant_handles || 829 !blkbk->pending_pages) { 830 rc = -ENOMEM; 831 goto out_of_memory; 832 } 833 834 for (i = 0; i < mmap_pages; i++) { 835 blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE; 836 blkbk->pending_pages[i] = alloc_page(GFP_KERNEL); 837 if (blkbk->pending_pages[i] == NULL) { 838 rc = -ENOMEM; 839 goto out_of_memory; 840 } 841 } 842 rc = xen_blkif_interface_init(); 843 if (rc) 844 goto failed_init; 845 846 INIT_LIST_HEAD(&blkbk->pending_free); 847 spin_lock_init(&blkbk->pending_free_lock); 848 init_waitqueue_head(&blkbk->pending_free_wq); 849 850 for (i = 0; i < xen_blkif_reqs; i++) 851 list_add_tail(&blkbk->pending_reqs[i].free_list, 852 &blkbk->pending_free); 853 854 rc = xen_blkif_xenbus_init(); 855 if (rc) 856 goto failed_init; 857 858 return 0; 859 860 out_of_memory: 861 pr_alert(DRV_PFX "%s: out of memory\n", __func__); 862 failed_init: 863 kfree(blkbk->pending_reqs); 864 kfree(blkbk->pending_grant_handles); 865 if (blkbk->pending_pages) { 866 for (i = 0; i < mmap_pages; i++) { 867 if (blkbk->pending_pages[i]) 868 __free_page(blkbk->pending_pages[i]); 869 } 870 kfree(blkbk->pending_pages); 871 } 872 kfree(blkbk); 873 blkbk = NULL; 874 return rc; 875 } 876 877 module_init(xen_blkif_init); 878 879 MODULE_LICENSE("Dual BSD/GPL"); 880 MODULE_ALIAS("xen-backend:vbd"); 881