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