1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/fs/nfs/direct.c 4 * 5 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com> 6 * 7 * High-performance uncached I/O for the Linux NFS client 8 * 9 * There are important applications whose performance or correctness 10 * depends on uncached access to file data. Database clusters 11 * (multiple copies of the same instance running on separate hosts) 12 * implement their own cache coherency protocol that subsumes file 13 * system cache protocols. Applications that process datasets 14 * considerably larger than the client's memory do not always benefit 15 * from a local cache. A streaming video server, for instance, has no 16 * need to cache the contents of a file. 17 * 18 * When an application requests uncached I/O, all read and write requests 19 * are made directly to the server; data stored or fetched via these 20 * requests is not cached in the Linux page cache. The client does not 21 * correct unaligned requests from applications. All requested bytes are 22 * held on permanent storage before a direct write system call returns to 23 * an application. 24 * 25 * Solaris implements an uncached I/O facility called directio() that 26 * is used for backups and sequential I/O to very large files. Solaris 27 * also supports uncaching whole NFS partitions with "-o forcedirectio," 28 * an undocumented mount option. 29 * 30 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with 31 * help from Andrew Morton. 32 * 33 * 18 Dec 2001 Initial implementation for 2.4 --cel 34 * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy 35 * 08 Jun 2003 Port to 2.5 APIs --cel 36 * 31 Mar 2004 Handle direct I/O without VFS support --cel 37 * 15 Sep 2004 Parallel async reads --cel 38 * 04 May 2005 support O_DIRECT with aio --cel 39 * 40 */ 41 42 #include <linux/errno.h> 43 #include <linux/sched.h> 44 #include <linux/kernel.h> 45 #include <linux/file.h> 46 #include <linux/pagemap.h> 47 #include <linux/kref.h> 48 #include <linux/slab.h> 49 #include <linux/task_io_accounting_ops.h> 50 #include <linux/module.h> 51 52 #include <linux/nfs_fs.h> 53 #include <linux/nfs_page.h> 54 #include <linux/sunrpc/clnt.h> 55 56 #include <linux/uaccess.h> 57 #include <linux/atomic.h> 58 59 #include "internal.h" 60 #include "iostat.h" 61 #include "pnfs.h" 62 #include "fscache.h" 63 #include "nfstrace.h" 64 65 #define NFSDBG_FACILITY NFSDBG_VFS 66 67 static struct kmem_cache *nfs_direct_cachep; 68 69 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops; 70 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops; 71 static void nfs_direct_write_complete(struct nfs_direct_req *dreq); 72 static void nfs_direct_write_schedule_work(struct work_struct *work); 73 74 static inline void get_dreq(struct nfs_direct_req *dreq) 75 { 76 atomic_inc(&dreq->io_count); 77 } 78 79 static inline int put_dreq(struct nfs_direct_req *dreq) 80 { 81 return atomic_dec_and_test(&dreq->io_count); 82 } 83 84 static void 85 nfs_direct_handle_truncated(struct nfs_direct_req *dreq, 86 const struct nfs_pgio_header *hdr, 87 ssize_t dreq_len) 88 { 89 if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) || 90 test_bit(NFS_IOHDR_EOF, &hdr->flags))) 91 return; 92 if (dreq->max_count >= dreq_len) { 93 dreq->max_count = dreq_len; 94 if (dreq->count > dreq_len) 95 dreq->count = dreq_len; 96 97 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) 98 dreq->error = hdr->error; 99 else /* Clear outstanding error if this is EOF */ 100 dreq->error = 0; 101 } 102 } 103 104 static void 105 nfs_direct_count_bytes(struct nfs_direct_req *dreq, 106 const struct nfs_pgio_header *hdr) 107 { 108 loff_t hdr_end = hdr->io_start + hdr->good_bytes; 109 ssize_t dreq_len = 0; 110 111 if (hdr_end > dreq->io_start) 112 dreq_len = hdr_end - dreq->io_start; 113 114 nfs_direct_handle_truncated(dreq, hdr, dreq_len); 115 116 if (dreq_len > dreq->max_count) 117 dreq_len = dreq->max_count; 118 119 if (dreq->count < dreq_len) 120 dreq->count = dreq_len; 121 } 122 123 /** 124 * nfs_swap_rw - NFS address space operation for swap I/O 125 * @iocb: target I/O control block 126 * @iter: I/O buffer 127 * 128 * Perform IO to the swap-file. This is much like direct IO. 129 */ 130 int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter) 131 { 132 ssize_t ret; 133 134 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE); 135 136 if (iov_iter_rw(iter) == READ) 137 ret = nfs_file_direct_read(iocb, iter, true); 138 else 139 ret = nfs_file_direct_write(iocb, iter, true); 140 if (ret < 0) 141 return ret; 142 return 0; 143 } 144 145 static void nfs_direct_release_pages(struct page **pages, unsigned int npages) 146 { 147 unsigned int i; 148 for (i = 0; i < npages; i++) 149 put_page(pages[i]); 150 } 151 152 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo, 153 struct nfs_direct_req *dreq) 154 { 155 cinfo->inode = dreq->inode; 156 cinfo->mds = &dreq->mds_cinfo; 157 cinfo->ds = &dreq->ds_cinfo; 158 cinfo->dreq = dreq; 159 cinfo->completion_ops = &nfs_direct_commit_completion_ops; 160 } 161 162 static inline struct nfs_direct_req *nfs_direct_req_alloc(void) 163 { 164 struct nfs_direct_req *dreq; 165 166 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL); 167 if (!dreq) 168 return NULL; 169 170 kref_init(&dreq->kref); 171 kref_get(&dreq->kref); 172 init_completion(&dreq->completion); 173 INIT_LIST_HEAD(&dreq->mds_cinfo.list); 174 pnfs_init_ds_commit_info(&dreq->ds_cinfo); 175 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work); 176 spin_lock_init(&dreq->lock); 177 178 return dreq; 179 } 180 181 static void nfs_direct_req_free(struct kref *kref) 182 { 183 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref); 184 185 pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode); 186 if (dreq->l_ctx != NULL) 187 nfs_put_lock_context(dreq->l_ctx); 188 if (dreq->ctx != NULL) 189 put_nfs_open_context(dreq->ctx); 190 kmem_cache_free(nfs_direct_cachep, dreq); 191 } 192 193 static void nfs_direct_req_release(struct nfs_direct_req *dreq) 194 { 195 kref_put(&dreq->kref, nfs_direct_req_free); 196 } 197 198 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq) 199 { 200 return dreq->bytes_left; 201 } 202 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left); 203 204 /* 205 * Collects and returns the final error value/byte-count. 206 */ 207 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq) 208 { 209 ssize_t result = -EIOCBQUEUED; 210 211 /* Async requests don't wait here */ 212 if (dreq->iocb) 213 goto out; 214 215 result = wait_for_completion_killable(&dreq->completion); 216 217 if (!result) { 218 result = dreq->count; 219 WARN_ON_ONCE(dreq->count < 0); 220 } 221 if (!result) 222 result = dreq->error; 223 224 out: 225 return (ssize_t) result; 226 } 227 228 /* 229 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust 230 * the iocb is still valid here if this is a synchronous request. 231 */ 232 static void nfs_direct_complete(struct nfs_direct_req *dreq) 233 { 234 struct inode *inode = dreq->inode; 235 236 inode_dio_end(inode); 237 238 if (dreq->iocb) { 239 long res = (long) dreq->error; 240 if (dreq->count != 0) { 241 res = (long) dreq->count; 242 WARN_ON_ONCE(dreq->count < 0); 243 } 244 dreq->iocb->ki_complete(dreq->iocb, res); 245 } 246 247 complete(&dreq->completion); 248 249 nfs_direct_req_release(dreq); 250 } 251 252 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) 253 { 254 unsigned long bytes = 0; 255 struct nfs_direct_req *dreq = hdr->dreq; 256 257 spin_lock(&dreq->lock); 258 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { 259 spin_unlock(&dreq->lock); 260 goto out_put; 261 } 262 263 nfs_direct_count_bytes(dreq, hdr); 264 spin_unlock(&dreq->lock); 265 266 while (!list_empty(&hdr->pages)) { 267 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 268 struct page *page = req->wb_page; 269 270 if (!PageCompound(page) && bytes < hdr->good_bytes && 271 (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY)) 272 set_page_dirty(page); 273 bytes += req->wb_bytes; 274 nfs_list_remove_request(req); 275 nfs_release_request(req); 276 } 277 out_put: 278 if (put_dreq(dreq)) 279 nfs_direct_complete(dreq); 280 hdr->release(hdr); 281 } 282 283 static void nfs_read_sync_pgio_error(struct list_head *head, int error) 284 { 285 struct nfs_page *req; 286 287 while (!list_empty(head)) { 288 req = nfs_list_entry(head->next); 289 nfs_list_remove_request(req); 290 nfs_release_request(req); 291 } 292 } 293 294 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr) 295 { 296 get_dreq(hdr->dreq); 297 } 298 299 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = { 300 .error_cleanup = nfs_read_sync_pgio_error, 301 .init_hdr = nfs_direct_pgio_init, 302 .completion = nfs_direct_read_completion, 303 }; 304 305 /* 306 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ 307 * operation. If nfs_readdata_alloc() or get_user_pages() fails, 308 * bail and stop sending more reads. Read length accounting is 309 * handled automatically by nfs_direct_read_result(). Otherwise, if 310 * no requests have been sent, just return an error. 311 */ 312 313 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq, 314 struct iov_iter *iter, 315 loff_t pos) 316 { 317 struct nfs_pageio_descriptor desc; 318 struct inode *inode = dreq->inode; 319 ssize_t result = -EINVAL; 320 size_t requested_bytes = 0; 321 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE); 322 323 nfs_pageio_init_read(&desc, dreq->inode, false, 324 &nfs_direct_read_completion_ops); 325 get_dreq(dreq); 326 desc.pg_dreq = dreq; 327 inode_dio_begin(inode); 328 329 while (iov_iter_count(iter)) { 330 struct page **pagevec; 331 size_t bytes; 332 size_t pgbase; 333 unsigned npages, i; 334 335 result = iov_iter_get_pages_alloc2(iter, &pagevec, 336 rsize, &pgbase); 337 if (result < 0) 338 break; 339 340 bytes = result; 341 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 342 for (i = 0; i < npages; i++) { 343 struct nfs_page *req; 344 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 345 /* XXX do we need to do the eof zeroing found in async_filler? */ 346 req = nfs_page_create_from_page(dreq->ctx, pagevec[i], 347 pgbase, pos, req_len); 348 if (IS_ERR(req)) { 349 result = PTR_ERR(req); 350 break; 351 } 352 if (!nfs_pageio_add_request(&desc, req)) { 353 result = desc.pg_error; 354 nfs_release_request(req); 355 break; 356 } 357 pgbase = 0; 358 bytes -= req_len; 359 requested_bytes += req_len; 360 pos += req_len; 361 dreq->bytes_left -= req_len; 362 } 363 nfs_direct_release_pages(pagevec, npages); 364 kvfree(pagevec); 365 if (result < 0) 366 break; 367 } 368 369 nfs_pageio_complete(&desc); 370 371 /* 372 * If no bytes were started, return the error, and let the 373 * generic layer handle the completion. 374 */ 375 if (requested_bytes == 0) { 376 inode_dio_end(inode); 377 nfs_direct_req_release(dreq); 378 return result < 0 ? result : -EIO; 379 } 380 381 if (put_dreq(dreq)) 382 nfs_direct_complete(dreq); 383 return requested_bytes; 384 } 385 386 /** 387 * nfs_file_direct_read - file direct read operation for NFS files 388 * @iocb: target I/O control block 389 * @iter: vector of user buffers into which to read data 390 * @swap: flag indicating this is swap IO, not O_DIRECT IO 391 * 392 * We use this function for direct reads instead of calling 393 * generic_file_aio_read() in order to avoid gfar's check to see if 394 * the request starts before the end of the file. For that check 395 * to work, we must generate a GETATTR before each direct read, and 396 * even then there is a window between the GETATTR and the subsequent 397 * READ where the file size could change. Our preference is simply 398 * to do all reads the application wants, and the server will take 399 * care of managing the end of file boundary. 400 * 401 * This function also eliminates unnecessarily updating the file's 402 * atime locally, as the NFS server sets the file's atime, and this 403 * client must read the updated atime from the server back into its 404 * cache. 405 */ 406 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter, 407 bool swap) 408 { 409 struct file *file = iocb->ki_filp; 410 struct address_space *mapping = file->f_mapping; 411 struct inode *inode = mapping->host; 412 struct nfs_direct_req *dreq; 413 struct nfs_lock_context *l_ctx; 414 ssize_t result, requested; 415 size_t count = iov_iter_count(iter); 416 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count); 417 418 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n", 419 file, count, (long long) iocb->ki_pos); 420 421 result = 0; 422 if (!count) 423 goto out; 424 425 task_io_account_read(count); 426 427 result = -ENOMEM; 428 dreq = nfs_direct_req_alloc(); 429 if (dreq == NULL) 430 goto out; 431 432 dreq->inode = inode; 433 dreq->bytes_left = dreq->max_count = count; 434 dreq->io_start = iocb->ki_pos; 435 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 436 l_ctx = nfs_get_lock_context(dreq->ctx); 437 if (IS_ERR(l_ctx)) { 438 result = PTR_ERR(l_ctx); 439 nfs_direct_req_release(dreq); 440 goto out_release; 441 } 442 dreq->l_ctx = l_ctx; 443 if (!is_sync_kiocb(iocb)) 444 dreq->iocb = iocb; 445 446 if (user_backed_iter(iter)) 447 dreq->flags = NFS_ODIRECT_SHOULD_DIRTY; 448 449 if (!swap) 450 nfs_start_io_direct(inode); 451 452 NFS_I(inode)->read_io += count; 453 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos); 454 455 if (!swap) 456 nfs_end_io_direct(inode); 457 458 if (requested > 0) { 459 result = nfs_direct_wait(dreq); 460 if (result > 0) { 461 requested -= result; 462 iocb->ki_pos += result; 463 } 464 iov_iter_revert(iter, requested); 465 } else { 466 result = requested; 467 } 468 469 out_release: 470 nfs_direct_req_release(dreq); 471 out: 472 return result; 473 } 474 475 static void 476 nfs_direct_join_group(struct list_head *list, struct inode *inode) 477 { 478 struct nfs_page *req, *next; 479 480 list_for_each_entry(req, list, wb_list) { 481 if (req->wb_head != req || req->wb_this_page == req) 482 continue; 483 for (next = req->wb_this_page; 484 next != req->wb_head; 485 next = next->wb_this_page) { 486 nfs_list_remove_request(next); 487 nfs_release_request(next); 488 } 489 nfs_join_page_group(req, inode); 490 } 491 } 492 493 static void 494 nfs_direct_write_scan_commit_list(struct inode *inode, 495 struct list_head *list, 496 struct nfs_commit_info *cinfo) 497 { 498 mutex_lock(&NFS_I(cinfo->inode)->commit_mutex); 499 pnfs_recover_commit_reqs(list, cinfo); 500 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0); 501 mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex); 502 } 503 504 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) 505 { 506 struct nfs_pageio_descriptor desc; 507 struct nfs_page *req, *tmp; 508 LIST_HEAD(reqs); 509 struct nfs_commit_info cinfo; 510 LIST_HEAD(failed); 511 512 nfs_init_cinfo_from_dreq(&cinfo, dreq); 513 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 514 515 nfs_direct_join_group(&reqs, dreq->inode); 516 517 dreq->count = 0; 518 dreq->max_count = 0; 519 list_for_each_entry(req, &reqs, wb_list) 520 dreq->max_count += req->wb_bytes; 521 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo); 522 get_dreq(dreq); 523 524 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false, 525 &nfs_direct_write_completion_ops); 526 desc.pg_dreq = dreq; 527 528 list_for_each_entry_safe(req, tmp, &reqs, wb_list) { 529 /* Bump the transmission count */ 530 req->wb_nio++; 531 if (!nfs_pageio_add_request(&desc, req)) { 532 nfs_list_move_request(req, &failed); 533 spin_lock(&cinfo.inode->i_lock); 534 dreq->flags = 0; 535 if (desc.pg_error < 0) 536 dreq->error = desc.pg_error; 537 else 538 dreq->error = -EIO; 539 spin_unlock(&cinfo.inode->i_lock); 540 } 541 nfs_release_request(req); 542 } 543 nfs_pageio_complete(&desc); 544 545 while (!list_empty(&failed)) { 546 req = nfs_list_entry(failed.next); 547 nfs_list_remove_request(req); 548 nfs_unlock_and_release_request(req); 549 } 550 551 if (put_dreq(dreq)) 552 nfs_direct_write_complete(dreq); 553 } 554 555 static void nfs_direct_commit_complete(struct nfs_commit_data *data) 556 { 557 const struct nfs_writeverf *verf = data->res.verf; 558 struct nfs_direct_req *dreq = data->dreq; 559 struct nfs_commit_info cinfo; 560 struct nfs_page *req; 561 int status = data->task.tk_status; 562 563 trace_nfs_direct_commit_complete(dreq); 564 565 if (status < 0) { 566 /* Errors in commit are fatal */ 567 dreq->error = status; 568 dreq->max_count = 0; 569 dreq->count = 0; 570 dreq->flags = NFS_ODIRECT_DONE; 571 } else { 572 status = dreq->error; 573 } 574 575 nfs_init_cinfo_from_dreq(&cinfo, dreq); 576 577 while (!list_empty(&data->pages)) { 578 req = nfs_list_entry(data->pages.next); 579 nfs_list_remove_request(req); 580 if (status >= 0 && !nfs_write_match_verf(verf, req)) { 581 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 582 /* 583 * Despite the reboot, the write was successful, 584 * so reset wb_nio. 585 */ 586 req->wb_nio = 0; 587 nfs_mark_request_commit(req, NULL, &cinfo, 0); 588 } else /* Error or match */ 589 nfs_release_request(req); 590 nfs_unlock_and_release_request(req); 591 } 592 593 if (nfs_commit_end(cinfo.mds)) 594 nfs_direct_write_complete(dreq); 595 } 596 597 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo, 598 struct nfs_page *req) 599 { 600 struct nfs_direct_req *dreq = cinfo->dreq; 601 602 trace_nfs_direct_resched_write(dreq); 603 604 spin_lock(&dreq->lock); 605 if (dreq->flags != NFS_ODIRECT_DONE) 606 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 607 spin_unlock(&dreq->lock); 608 nfs_mark_request_commit(req, NULL, cinfo, 0); 609 } 610 611 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = { 612 .completion = nfs_direct_commit_complete, 613 .resched_write = nfs_direct_resched_write, 614 }; 615 616 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) 617 { 618 int res; 619 struct nfs_commit_info cinfo; 620 LIST_HEAD(mds_list); 621 622 nfs_init_cinfo_from_dreq(&cinfo, dreq); 623 nfs_scan_commit(dreq->inode, &mds_list, &cinfo); 624 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo); 625 if (res < 0) /* res == -ENOMEM */ 626 nfs_direct_write_reschedule(dreq); 627 } 628 629 static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq) 630 { 631 struct nfs_commit_info cinfo; 632 struct nfs_page *req; 633 LIST_HEAD(reqs); 634 635 nfs_init_cinfo_from_dreq(&cinfo, dreq); 636 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 637 638 while (!list_empty(&reqs)) { 639 req = nfs_list_entry(reqs.next); 640 nfs_list_remove_request(req); 641 nfs_release_request(req); 642 nfs_unlock_and_release_request(req); 643 } 644 } 645 646 static void nfs_direct_write_schedule_work(struct work_struct *work) 647 { 648 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work); 649 int flags = dreq->flags; 650 651 dreq->flags = 0; 652 switch (flags) { 653 case NFS_ODIRECT_DO_COMMIT: 654 nfs_direct_commit_schedule(dreq); 655 break; 656 case NFS_ODIRECT_RESCHED_WRITES: 657 nfs_direct_write_reschedule(dreq); 658 break; 659 default: 660 nfs_direct_write_clear_reqs(dreq); 661 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping); 662 nfs_direct_complete(dreq); 663 } 664 } 665 666 static void nfs_direct_write_complete(struct nfs_direct_req *dreq) 667 { 668 trace_nfs_direct_write_complete(dreq); 669 queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */ 670 } 671 672 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) 673 { 674 struct nfs_direct_req *dreq = hdr->dreq; 675 struct nfs_commit_info cinfo; 676 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 677 int flags = NFS_ODIRECT_DONE; 678 679 trace_nfs_direct_write_completion(dreq); 680 681 nfs_init_cinfo_from_dreq(&cinfo, dreq); 682 683 spin_lock(&dreq->lock); 684 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { 685 spin_unlock(&dreq->lock); 686 goto out_put; 687 } 688 689 nfs_direct_count_bytes(dreq, hdr); 690 if (test_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags)) { 691 if (!dreq->flags) 692 dreq->flags = NFS_ODIRECT_DO_COMMIT; 693 flags = dreq->flags; 694 } 695 spin_unlock(&dreq->lock); 696 697 while (!list_empty(&hdr->pages)) { 698 699 req = nfs_list_entry(hdr->pages.next); 700 nfs_list_remove_request(req); 701 if (flags == NFS_ODIRECT_DO_COMMIT) { 702 kref_get(&req->wb_kref); 703 memcpy(&req->wb_verf, &hdr->verf.verifier, 704 sizeof(req->wb_verf)); 705 nfs_mark_request_commit(req, hdr->lseg, &cinfo, 706 hdr->ds_commit_idx); 707 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) { 708 kref_get(&req->wb_kref); 709 nfs_mark_request_commit(req, NULL, &cinfo, 0); 710 } 711 nfs_unlock_and_release_request(req); 712 } 713 714 out_put: 715 if (put_dreq(dreq)) 716 nfs_direct_write_complete(dreq); 717 hdr->release(hdr); 718 } 719 720 static void nfs_write_sync_pgio_error(struct list_head *head, int error) 721 { 722 struct nfs_page *req; 723 724 while (!list_empty(head)) { 725 req = nfs_list_entry(head->next); 726 nfs_list_remove_request(req); 727 nfs_unlock_and_release_request(req); 728 } 729 } 730 731 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr) 732 { 733 struct nfs_direct_req *dreq = hdr->dreq; 734 735 trace_nfs_direct_write_reschedule_io(dreq); 736 737 spin_lock(&dreq->lock); 738 if (dreq->error == 0) { 739 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 740 /* fake unstable write to let common nfs resend pages */ 741 hdr->verf.committed = NFS_UNSTABLE; 742 hdr->good_bytes = hdr->args.offset + hdr->args.count - 743 hdr->io_start; 744 } 745 spin_unlock(&dreq->lock); 746 } 747 748 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = { 749 .error_cleanup = nfs_write_sync_pgio_error, 750 .init_hdr = nfs_direct_pgio_init, 751 .completion = nfs_direct_write_completion, 752 .reschedule_io = nfs_direct_write_reschedule_io, 753 }; 754 755 756 /* 757 * NB: Return the value of the first error return code. Subsequent 758 * errors after the first one are ignored. 759 */ 760 /* 761 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE 762 * operation. If nfs_writedata_alloc() or get_user_pages() fails, 763 * bail and stop sending more writes. Write length accounting is 764 * handled automatically by nfs_direct_write_result(). Otherwise, if 765 * no requests have been sent, just return an error. 766 */ 767 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq, 768 struct iov_iter *iter, 769 loff_t pos, int ioflags) 770 { 771 struct nfs_pageio_descriptor desc; 772 struct inode *inode = dreq->inode; 773 ssize_t result = 0; 774 size_t requested_bytes = 0; 775 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE); 776 777 trace_nfs_direct_write_schedule_iovec(dreq); 778 779 nfs_pageio_init_write(&desc, inode, ioflags, false, 780 &nfs_direct_write_completion_ops); 781 desc.pg_dreq = dreq; 782 get_dreq(dreq); 783 inode_dio_begin(inode); 784 785 NFS_I(inode)->write_io += iov_iter_count(iter); 786 while (iov_iter_count(iter)) { 787 struct page **pagevec; 788 size_t bytes; 789 size_t pgbase; 790 unsigned npages, i; 791 792 result = iov_iter_get_pages_alloc2(iter, &pagevec, 793 wsize, &pgbase); 794 if (result < 0) 795 break; 796 797 bytes = result; 798 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 799 for (i = 0; i < npages; i++) { 800 struct nfs_page *req; 801 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 802 803 req = nfs_page_create_from_page(dreq->ctx, pagevec[i], 804 pgbase, pos, req_len); 805 if (IS_ERR(req)) { 806 result = PTR_ERR(req); 807 break; 808 } 809 810 if (desc.pg_error < 0) { 811 nfs_free_request(req); 812 result = desc.pg_error; 813 break; 814 } 815 816 nfs_lock_request(req); 817 if (!nfs_pageio_add_request(&desc, req)) { 818 result = desc.pg_error; 819 nfs_unlock_and_release_request(req); 820 break; 821 } 822 pgbase = 0; 823 bytes -= req_len; 824 requested_bytes += req_len; 825 pos += req_len; 826 dreq->bytes_left -= req_len; 827 } 828 nfs_direct_release_pages(pagevec, npages); 829 kvfree(pagevec); 830 if (result < 0) 831 break; 832 } 833 nfs_pageio_complete(&desc); 834 835 /* 836 * If no bytes were started, return the error, and let the 837 * generic layer handle the completion. 838 */ 839 if (requested_bytes == 0) { 840 inode_dio_end(inode); 841 nfs_direct_req_release(dreq); 842 return result < 0 ? result : -EIO; 843 } 844 845 if (put_dreq(dreq)) 846 nfs_direct_write_complete(dreq); 847 return requested_bytes; 848 } 849 850 /** 851 * nfs_file_direct_write - file direct write operation for NFS files 852 * @iocb: target I/O control block 853 * @iter: vector of user buffers from which to write data 854 * @swap: flag indicating this is swap IO, not O_DIRECT IO 855 * 856 * We use this function for direct writes instead of calling 857 * generic_file_aio_write() in order to avoid taking the inode 858 * semaphore and updating the i_size. The NFS server will set 859 * the new i_size and this client must read the updated size 860 * back into its cache. We let the server do generic write 861 * parameter checking and report problems. 862 * 863 * We eliminate local atime updates, see direct read above. 864 * 865 * We avoid unnecessary page cache invalidations for normal cached 866 * readers of this file. 867 * 868 * Note that O_APPEND is not supported for NFS direct writes, as there 869 * is no atomic O_APPEND write facility in the NFS protocol. 870 */ 871 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter, 872 bool swap) 873 { 874 ssize_t result, requested; 875 size_t count; 876 struct file *file = iocb->ki_filp; 877 struct address_space *mapping = file->f_mapping; 878 struct inode *inode = mapping->host; 879 struct nfs_direct_req *dreq; 880 struct nfs_lock_context *l_ctx; 881 loff_t pos, end; 882 883 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", 884 file, iov_iter_count(iter), (long long) iocb->ki_pos); 885 886 if (swap) 887 /* bypass generic checks */ 888 result = iov_iter_count(iter); 889 else 890 result = generic_write_checks(iocb, iter); 891 if (result <= 0) 892 return result; 893 count = result; 894 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count); 895 896 pos = iocb->ki_pos; 897 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT; 898 899 task_io_account_write(count); 900 901 result = -ENOMEM; 902 dreq = nfs_direct_req_alloc(); 903 if (!dreq) 904 goto out; 905 906 dreq->inode = inode; 907 dreq->bytes_left = dreq->max_count = count; 908 dreq->io_start = pos; 909 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 910 l_ctx = nfs_get_lock_context(dreq->ctx); 911 if (IS_ERR(l_ctx)) { 912 result = PTR_ERR(l_ctx); 913 nfs_direct_req_release(dreq); 914 goto out_release; 915 } 916 dreq->l_ctx = l_ctx; 917 if (!is_sync_kiocb(iocb)) 918 dreq->iocb = iocb; 919 pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode); 920 921 if (swap) { 922 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos, 923 FLUSH_STABLE); 924 } else { 925 nfs_start_io_direct(inode); 926 927 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos, 928 FLUSH_COND_STABLE); 929 930 if (mapping->nrpages) { 931 invalidate_inode_pages2_range(mapping, 932 pos >> PAGE_SHIFT, end); 933 } 934 935 nfs_end_io_direct(inode); 936 } 937 938 if (requested > 0) { 939 result = nfs_direct_wait(dreq); 940 if (result > 0) { 941 requested -= result; 942 iocb->ki_pos = pos + result; 943 /* XXX: should check the generic_write_sync retval */ 944 generic_write_sync(iocb, result); 945 } 946 iov_iter_revert(iter, requested); 947 } else { 948 result = requested; 949 } 950 nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE); 951 out_release: 952 nfs_direct_req_release(dreq); 953 out: 954 return result; 955 } 956 957 /** 958 * nfs_init_directcache - create a slab cache for nfs_direct_req structures 959 * 960 */ 961 int __init nfs_init_directcache(void) 962 { 963 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache", 964 sizeof(struct nfs_direct_req), 965 0, (SLAB_RECLAIM_ACCOUNT| 966 SLAB_MEM_SPREAD), 967 NULL); 968 if (nfs_direct_cachep == NULL) 969 return -ENOMEM; 970 971 return 0; 972 } 973 974 /** 975 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures 976 * 977 */ 978 void nfs_destroy_directcache(void) 979 { 980 kmem_cache_destroy(nfs_direct_cachep); 981 } 982