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 */ 59 static int xen_blkif_reqs = 64; 60 module_param_named(reqs, xen_blkif_reqs, int, 0); 61 MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate"); 62 63 /* Run-time switchable: /sys/module/blkback/parameters/ */ 64 static unsigned int log_stats; 65 module_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 */ 73 struct 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 85 struct 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 98 static 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 */ 106 static 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)] 113 114 static 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)]) 122 123 124 static int do_block_io_op(struct xen_blkif *blkif); 125 static int dispatch_rw_block_io(struct xen_blkif *blkif, 126 struct blkif_request *req, 127 struct pending_req *pending_req); 128 static 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 */ 134 static 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 */ 153 static 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 */ 169 static 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 } 194 195 static 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; 207 again: 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; 236 abort: 237 xenbus_transaction_end(xbt, 1); 238 } 239 240 /* 241 * Notification from the guest OS. 242 */ 243 static void blkif_notify_work(struct xen_blkif *blkif) 244 { 245 blkif->waiting_reqs = 1; 246 wake_up(&blkif->wq); 247 } 248 249 irqreturn_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 */ 258 259 static void print_stats(struct xen_blkif *blkif) 260 { 261 pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d\n", 262 current->comm, blkif->st_oo_req, 263 blkif->st_rd_req, blkif->st_wr_req, blkif->st_f_req); 264 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); 265 blkif->st_rd_req = 0; 266 blkif->st_wr_req = 0; 267 blkif->st_oo_req = 0; 268 } 269 270 int xen_blkif_schedule(void *arg) 271 { 272 struct xen_blkif *blkif = arg; 273 struct xen_vbd *vbd = &blkif->vbd; 274 275 xen_blkif_get(blkif); 276 277 while (!kthread_should_stop()) { 278 if (try_to_freeze()) 279 continue; 280 if (unlikely(vbd->size != vbd_sz(vbd))) 281 xen_vbd_resize(blkif); 282 283 wait_event_interruptible( 284 blkif->wq, 285 blkif->waiting_reqs || kthread_should_stop()); 286 wait_event_interruptible( 287 blkbk->pending_free_wq, 288 !list_empty(&blkbk->pending_free) || 289 kthread_should_stop()); 290 291 blkif->waiting_reqs = 0; 292 smp_mb(); /* clear flag *before* checking for work */ 293 294 if (do_block_io_op(blkif)) 295 blkif->waiting_reqs = 1; 296 297 if (log_stats && time_after(jiffies, blkif->st_print)) 298 print_stats(blkif); 299 } 300 301 if (log_stats) 302 print_stats(blkif); 303 304 blkif->xenblkd = NULL; 305 xen_blkif_put(blkif); 306 307 return 0; 308 } 309 310 struct seg_buf { 311 unsigned long buf; 312 unsigned int nsec; 313 }; 314 /* 315 * Unmap the grant references, and also remove the M2P over-rides 316 * used in the 'pending_req'. 317 */ 318 static void xen_blkbk_unmap(struct pending_req *req) 319 { 320 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 321 unsigned int i, invcount = 0; 322 grant_handle_t handle; 323 int ret; 324 325 for (i = 0; i < req->nr_pages; i++) { 326 handle = pending_handle(req, i); 327 if (handle == BLKBACK_INVALID_HANDLE) 328 continue; 329 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i), 330 GNTMAP_host_map, handle); 331 pending_handle(req, i) = BLKBACK_INVALID_HANDLE; 332 invcount++; 333 } 334 335 ret = HYPERVISOR_grant_table_op( 336 GNTTABOP_unmap_grant_ref, unmap, invcount); 337 BUG_ON(ret); 338 /* 339 * Note, we use invcount, so nr->pages, so we can't index 340 * using vaddr(req, i). 341 */ 342 for (i = 0; i < invcount; i++) { 343 ret = m2p_remove_override( 344 virt_to_page(unmap[i].host_addr), false); 345 if (ret) { 346 pr_alert(DRV_PFX "Failed to remove M2P override for %lx\n", 347 (unsigned long)unmap[i].host_addr); 348 continue; 349 } 350 } 351 } 352 353 static int xen_blkbk_map(struct blkif_request *req, 354 struct pending_req *pending_req, 355 struct seg_buf seg[]) 356 { 357 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 358 int i; 359 int nseg = req->nr_segments; 360 int ret = 0; 361 362 /* 363 * Fill out preq.nr_sects with proper amount of sectors, and setup 364 * assign map[..] with the PFN of the page in our domain with the 365 * corresponding grant reference for each page. 366 */ 367 for (i = 0; i < nseg; i++) { 368 uint32_t flags; 369 370 flags = GNTMAP_host_map; 371 if (pending_req->operation != BLKIF_OP_READ) 372 flags |= GNTMAP_readonly; 373 gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags, 374 req->u.rw.seg[i].gref, 375 pending_req->blkif->domid); 376 } 377 378 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg); 379 BUG_ON(ret); 380 381 /* 382 * Now swizzle the MFN in our domain with the MFN from the other domain 383 * so that when we access vaddr(pending_req,i) it has the contents of 384 * the page from the other domain. 385 */ 386 for (i = 0; i < nseg; i++) { 387 if (unlikely(map[i].status != 0)) { 388 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n"); 389 map[i].handle = BLKBACK_INVALID_HANDLE; 390 ret |= 1; 391 } 392 393 pending_handle(pending_req, i) = map[i].handle; 394 395 if (ret) 396 continue; 397 398 ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr), 399 blkbk->pending_page(pending_req, i), false); 400 if (ret) { 401 pr_alert(DRV_PFX "Failed to install M2P override for %lx (ret: %d)\n", 402 (unsigned long)map[i].dev_bus_addr, ret); 403 /* We could switch over to GNTTABOP_copy */ 404 continue; 405 } 406 407 seg[i].buf = map[i].dev_bus_addr | 408 (req->u.rw.seg[i].first_sect << 9); 409 } 410 return ret; 411 } 412 413 /* 414 * Completion callback on the bio's. Called as bh->b_end_io() 415 */ 416 417 static void __end_block_io_op(struct pending_req *pending_req, int error) 418 { 419 /* An error fails the entire request. */ 420 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && 421 (error == -EOPNOTSUPP)) { 422 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n"); 423 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); 424 pending_req->status = BLKIF_RSP_EOPNOTSUPP; 425 } else if (error) { 426 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation," 427 " error=%d\n", error); 428 pending_req->status = BLKIF_RSP_ERROR; 429 } 430 431 /* 432 * If all of the bio's have completed it is time to unmap 433 * the grant references associated with 'request' and provide 434 * the proper response on the ring. 435 */ 436 if (atomic_dec_and_test(&pending_req->pendcnt)) { 437 xen_blkbk_unmap(pending_req); 438 make_response(pending_req->blkif, pending_req->id, 439 pending_req->operation, pending_req->status); 440 xen_blkif_put(pending_req->blkif); 441 free_req(pending_req); 442 } 443 } 444 445 /* 446 * bio callback. 447 */ 448 static void end_block_io_op(struct bio *bio, int error) 449 { 450 __end_block_io_op(bio->bi_private, error); 451 bio_put(bio); 452 } 453 454 455 456 /* 457 * Function to copy the from the ring buffer the 'struct blkif_request' 458 * (which has the sectors we want, number of them, grant references, etc), 459 * and transmute it to the block API to hand it over to the proper block disk. 460 */ 461 static int do_block_io_op(struct xen_blkif *blkif) 462 { 463 union blkif_back_rings *blk_rings = &blkif->blk_rings; 464 struct blkif_request req; 465 struct pending_req *pending_req; 466 RING_IDX rc, rp; 467 int more_to_do = 0; 468 469 rc = blk_rings->common.req_cons; 470 rp = blk_rings->common.sring->req_prod; 471 rmb(); /* Ensure we see queued requests up to 'rp'. */ 472 473 while (rc != rp) { 474 475 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) 476 break; 477 478 if (kthread_should_stop()) { 479 more_to_do = 1; 480 break; 481 } 482 483 pending_req = alloc_req(); 484 if (NULL == pending_req) { 485 blkif->st_oo_req++; 486 more_to_do = 1; 487 break; 488 } 489 490 switch (blkif->blk_protocol) { 491 case BLKIF_PROTOCOL_NATIVE: 492 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); 493 break; 494 case BLKIF_PROTOCOL_X86_32: 495 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); 496 break; 497 case BLKIF_PROTOCOL_X86_64: 498 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); 499 break; 500 default: 501 BUG(); 502 } 503 blk_rings->common.req_cons = ++rc; /* before make_response() */ 504 505 /* Apply all sanity checks to /private copy/ of request. */ 506 barrier(); 507 508 if (dispatch_rw_block_io(blkif, &req, pending_req)) 509 break; 510 511 /* Yield point for this unbounded loop. */ 512 cond_resched(); 513 } 514 515 return more_to_do; 516 } 517 518 /* 519 * Transmutation of the 'struct blkif_request' to a proper 'struct bio' 520 * and call the 'submit_bio' to pass it to the underlying storage. 521 */ 522 static int dispatch_rw_block_io(struct xen_blkif *blkif, 523 struct blkif_request *req, 524 struct pending_req *pending_req) 525 { 526 struct phys_req preq; 527 struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 528 unsigned int nseg; 529 struct bio *bio = NULL; 530 struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 531 int i, nbio = 0; 532 int operation; 533 struct blk_plug plug; 534 535 switch (req->operation) { 536 case BLKIF_OP_READ: 537 blkif->st_rd_req++; 538 operation = READ; 539 break; 540 case BLKIF_OP_WRITE: 541 blkif->st_wr_req++; 542 operation = WRITE_ODIRECT; 543 break; 544 case BLKIF_OP_FLUSH_DISKCACHE: 545 blkif->st_f_req++; 546 operation = WRITE_FLUSH; 547 break; 548 case BLKIF_OP_WRITE_BARRIER: 549 default: 550 operation = 0; /* make gcc happy */ 551 goto fail_response; 552 break; 553 } 554 555 /* Check that the number of segments is sane. */ 556 nseg = req->nr_segments; 557 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || 558 unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 559 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n", 560 nseg); 561 /* Haven't submitted any bio's yet. */ 562 goto fail_response; 563 } 564 565 preq.dev = req->handle; 566 preq.sector_number = req->u.rw.sector_number; 567 preq.nr_sects = 0; 568 569 pending_req->blkif = blkif; 570 pending_req->id = req->id; 571 pending_req->operation = req->operation; 572 pending_req->status = BLKIF_RSP_OKAY; 573 pending_req->nr_pages = nseg; 574 575 for (i = 0; i < nseg; i++) { 576 seg[i].nsec = req->u.rw.seg[i].last_sect - 577 req->u.rw.seg[i].first_sect + 1; 578 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || 579 (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect)) 580 goto fail_response; 581 preq.nr_sects += seg[i].nsec; 582 583 } 584 585 if (xen_vbd_translate(&preq, blkif, operation) != 0) { 586 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n", 587 operation == READ ? "read" : "write", 588 preq.sector_number, 589 preq.sector_number + preq.nr_sects, preq.dev); 590 goto fail_response; 591 } 592 593 /* 594 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev 595 * is set there. 596 */ 597 for (i = 0; i < nseg; i++) { 598 if (((int)preq.sector_number|(int)seg[i].nsec) & 599 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { 600 pr_debug(DRV_PFX "Misaligned I/O request from domain %d", 601 blkif->domid); 602 goto fail_response; 603 } 604 } 605 606 /* 607 * If we have failed at this point, we need to undo the M2P override, 608 * set gnttab_set_unmap_op on all of the grant references and perform 609 * the hypercall to unmap the grants - that is all done in 610 * xen_blkbk_unmap. 611 */ 612 if (xen_blkbk_map(req, pending_req, seg)) 613 goto fail_flush; 614 615 /* This corresponding xen_blkif_put is done in __end_block_io_op */ 616 xen_blkif_get(blkif); 617 618 for (i = 0; i < nseg; i++) { 619 while ((bio == NULL) || 620 (bio_add_page(bio, 621 blkbk->pending_page(pending_req, i), 622 seg[i].nsec << 9, 623 seg[i].buf & ~PAGE_MASK) == 0)) { 624 625 bio = bio_alloc(GFP_KERNEL, nseg-i); 626 if (unlikely(bio == NULL)) 627 goto fail_put_bio; 628 629 biolist[nbio++] = bio; 630 bio->bi_bdev = preq.bdev; 631 bio->bi_private = pending_req; 632 bio->bi_end_io = end_block_io_op; 633 bio->bi_sector = preq.sector_number; 634 } 635 636 preq.sector_number += seg[i].nsec; 637 } 638 639 /* This will be hit if the operation was a flush. */ 640 if (!bio) { 641 BUG_ON(operation != WRITE_FLUSH); 642 643 bio = bio_alloc(GFP_KERNEL, 0); 644 if (unlikely(bio == NULL)) 645 goto fail_put_bio; 646 647 biolist[nbio++] = bio; 648 bio->bi_bdev = preq.bdev; 649 bio->bi_private = pending_req; 650 bio->bi_end_io = end_block_io_op; 651 } 652 653 /* 654 * We set it one so that the last submit_bio does not have to call 655 * atomic_inc. 656 */ 657 atomic_set(&pending_req->pendcnt, nbio); 658 659 /* Get a reference count for the disk queue and start sending I/O */ 660 blk_start_plug(&plug); 661 662 for (i = 0; i < nbio; i++) 663 submit_bio(operation, biolist[i]); 664 665 /* Let the I/Os go.. */ 666 blk_finish_plug(&plug); 667 668 if (operation == READ) 669 blkif->st_rd_sect += preq.nr_sects; 670 else if (operation == WRITE || operation == WRITE_FLUSH) 671 blkif->st_wr_sect += preq.nr_sects; 672 673 return 0; 674 675 fail_flush: 676 xen_blkbk_unmap(pending_req); 677 fail_response: 678 /* Haven't submitted any bio's yet. */ 679 make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR); 680 free_req(pending_req); 681 msleep(1); /* back off a bit */ 682 return -EIO; 683 684 fail_put_bio: 685 for (i = 0; i < nbio; i++) 686 bio_put(biolist[i]); 687 __end_block_io_op(pending_req, -EINVAL); 688 msleep(1); /* back off a bit */ 689 return -EIO; 690 } 691 692 693 694 /* 695 * Put a response on the ring on how the operation fared. 696 */ 697 static void make_response(struct xen_blkif *blkif, u64 id, 698 unsigned short op, int st) 699 { 700 struct blkif_response resp; 701 unsigned long flags; 702 union blkif_back_rings *blk_rings = &blkif->blk_rings; 703 int more_to_do = 0; 704 int notify; 705 706 resp.id = id; 707 resp.operation = op; 708 resp.status = st; 709 710 spin_lock_irqsave(&blkif->blk_ring_lock, flags); 711 /* Place on the response ring for the relevant domain. */ 712 switch (blkif->blk_protocol) { 713 case BLKIF_PROTOCOL_NATIVE: 714 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), 715 &resp, sizeof(resp)); 716 break; 717 case BLKIF_PROTOCOL_X86_32: 718 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), 719 &resp, sizeof(resp)); 720 break; 721 case BLKIF_PROTOCOL_X86_64: 722 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), 723 &resp, sizeof(resp)); 724 break; 725 default: 726 BUG(); 727 } 728 blk_rings->common.rsp_prod_pvt++; 729 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); 730 if (blk_rings->common.rsp_prod_pvt == blk_rings->common.req_cons) { 731 /* 732 * Tail check for pending requests. Allows frontend to avoid 733 * notifications if requests are already in flight (lower 734 * overheads and promotes batching). 735 */ 736 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); 737 738 } else if (RING_HAS_UNCONSUMED_REQUESTS(&blk_rings->common)) { 739 more_to_do = 1; 740 } 741 742 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); 743 744 if (more_to_do) 745 blkif_notify_work(blkif); 746 if (notify) 747 notify_remote_via_irq(blkif->irq); 748 } 749 750 static int __init xen_blkif_init(void) 751 { 752 int i, mmap_pages; 753 int rc = 0; 754 755 if (!xen_pv_domain()) 756 return -ENODEV; 757 758 blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL); 759 if (!blkbk) { 760 pr_alert(DRV_PFX "%s: out of memory!\n", __func__); 761 return -ENOMEM; 762 } 763 764 mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST; 765 766 blkbk->pending_reqs = kmalloc(sizeof(blkbk->pending_reqs[0]) * 767 xen_blkif_reqs, GFP_KERNEL); 768 blkbk->pending_grant_handles = kzalloc(sizeof(blkbk->pending_grant_handles[0]) * 769 mmap_pages, GFP_KERNEL); 770 blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) * 771 mmap_pages, GFP_KERNEL); 772 773 if (!blkbk->pending_reqs || !blkbk->pending_grant_handles || 774 !blkbk->pending_pages) { 775 rc = -ENOMEM; 776 goto out_of_memory; 777 } 778 779 for (i = 0; i < mmap_pages; i++) { 780 blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE; 781 blkbk->pending_pages[i] = alloc_page(GFP_KERNEL); 782 if (blkbk->pending_pages[i] == NULL) { 783 rc = -ENOMEM; 784 goto out_of_memory; 785 } 786 } 787 rc = xen_blkif_interface_init(); 788 if (rc) 789 goto failed_init; 790 791 memset(blkbk->pending_reqs, 0, sizeof(blkbk->pending_reqs)); 792 793 INIT_LIST_HEAD(&blkbk->pending_free); 794 spin_lock_init(&blkbk->pending_free_lock); 795 init_waitqueue_head(&blkbk->pending_free_wq); 796 797 for (i = 0; i < xen_blkif_reqs; i++) 798 list_add_tail(&blkbk->pending_reqs[i].free_list, 799 &blkbk->pending_free); 800 801 rc = xen_blkif_xenbus_init(); 802 if (rc) 803 goto failed_init; 804 805 return 0; 806 807 out_of_memory: 808 pr_alert(DRV_PFX "%s: out of memory\n", __func__); 809 failed_init: 810 kfree(blkbk->pending_reqs); 811 kfree(blkbk->pending_grant_handles); 812 if (blkbk->pending_pages) { 813 for (i = 0; i < mmap_pages; i++) { 814 if (blkbk->pending_pages[i]) 815 __free_page(blkbk->pending_pages[i]); 816 } 817 kfree(blkbk->pending_pages); 818 } 819 kfree(blkbk); 820 blkbk = NULL; 821 return rc; 822 } 823 824 module_init(xen_blkif_init); 825 826 MODULE_LICENSE("Dual BSD/GPL"); 827