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 67static struct kmem_cache *nfs_direct_cachep; 68 69static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops; 70static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops; 71static void nfs_direct_write_complete(struct nfs_direct_req *dreq); 72static void nfs_direct_write_schedule_work(struct work_struct *work); 73 74static inline void get_dreq(struct nfs_direct_req *dreq) 75{ 76 atomic_inc(&dreq->io_count); 77} 78 79static inline int put_dreq(struct nfs_direct_req *dreq) 80{ 81 return atomic_dec_and_test(&dreq->io_count); 82} 83 84static void 85nfs_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 98 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && !dreq->error) 99 dreq->error = hdr->error; 100} 101 102static void 103nfs_direct_count_bytes(struct nfs_direct_req *dreq, 104 const struct nfs_pgio_header *hdr) 105{ 106 loff_t hdr_end = hdr->io_start + hdr->good_bytes; 107 ssize_t dreq_len = 0; 108 109 if (hdr_end > dreq->io_start) 110 dreq_len = hdr_end - dreq->io_start; 111 112 nfs_direct_handle_truncated(dreq, hdr, dreq_len); 113 114 if (dreq_len > dreq->max_count) 115 dreq_len = dreq->max_count; 116 117 if (dreq->count < dreq_len) 118 dreq->count = dreq_len; 119} 120 121static void nfs_direct_truncate_request(struct nfs_direct_req *dreq, 122 struct nfs_page *req) 123{ 124 loff_t offs = req_offset(req); 125 size_t req_start = (size_t)(offs - dreq->io_start); 126 127 if (req_start < dreq->max_count) 128 dreq->max_count = req_start; 129 if (req_start < dreq->count) 130 dreq->count = req_start; 131} 132 133/** 134 * nfs_swap_rw - NFS address space operation for swap I/O 135 * @iocb: target I/O control block 136 * @iter: I/O buffer 137 * 138 * Perform IO to the swap-file. This is much like direct IO. 139 */ 140int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter) 141{ 142 ssize_t ret; 143 144 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE); 145 146 if (iov_iter_rw(iter) == READ) 147 ret = nfs_file_direct_read(iocb, iter, true); 148 else 149 ret = nfs_file_direct_write(iocb, iter, true); 150 if (ret < 0) 151 return ret; 152 return 0; 153} 154 155static void nfs_direct_release_pages(struct page **pages, unsigned int npages) 156{ 157 unsigned int i; 158 for (i = 0; i < npages; i++) 159 put_page(pages[i]); 160} 161 162void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo, 163 struct nfs_direct_req *dreq) 164{ 165 cinfo->inode = dreq->inode; 166 cinfo->mds = &dreq->mds_cinfo; 167 cinfo->ds = &dreq->ds_cinfo; 168 cinfo->dreq = dreq; 169 cinfo->completion_ops = &nfs_direct_commit_completion_ops; 170} 171 172static inline struct nfs_direct_req *nfs_direct_req_alloc(void) 173{ 174 struct nfs_direct_req *dreq; 175 176 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL); 177 if (!dreq) 178 return NULL; 179 180 kref_init(&dreq->kref); 181 kref_get(&dreq->kref); 182 init_completion(&dreq->completion); 183 INIT_LIST_HEAD(&dreq->mds_cinfo.list); 184 pnfs_init_ds_commit_info(&dreq->ds_cinfo); 185 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work); 186 spin_lock_init(&dreq->lock); 187 188 return dreq; 189} 190 191static void nfs_direct_req_free(struct kref *kref) 192{ 193 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref); 194 195 pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode); 196 if (dreq->l_ctx != NULL) 197 nfs_put_lock_context(dreq->l_ctx); 198 if (dreq->ctx != NULL) 199 put_nfs_open_context(dreq->ctx); 200 kmem_cache_free(nfs_direct_cachep, dreq); 201} 202 203static void nfs_direct_req_release(struct nfs_direct_req *dreq) 204{ 205 kref_put(&dreq->kref, nfs_direct_req_free); 206} 207 208ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset) 209{ 210 loff_t start = offset - dreq->io_start; 211 return dreq->max_count - start; 212} 213EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left); 214 215/* 216 * Collects and returns the final error value/byte-count. 217 */ 218static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq) 219{ 220 ssize_t result = -EIOCBQUEUED; 221 222 /* Async requests don't wait here */ 223 if (dreq->iocb) 224 goto out; 225 226 result = wait_for_completion_killable(&dreq->completion); 227 228 if (!result) { 229 result = dreq->count; 230 WARN_ON_ONCE(dreq->count < 0); 231 } 232 if (!result) 233 result = dreq->error; 234 235out: 236 return (ssize_t) result; 237} 238 239/* 240 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust 241 * the iocb is still valid here if this is a synchronous request. 242 */ 243static void nfs_direct_complete(struct nfs_direct_req *dreq) 244{ 245 struct inode *inode = dreq->inode; 246 247 inode_dio_end(inode); 248 249 if (dreq->iocb) { 250 long res = (long) dreq->error; 251 if (dreq->count != 0) { 252 res = (long) dreq->count; 253 WARN_ON_ONCE(dreq->count < 0); 254 } 255 dreq->iocb->ki_complete(dreq->iocb, res); 256 } 257 258 complete(&dreq->completion); 259 260 nfs_direct_req_release(dreq); 261} 262 263static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) 264{ 265 unsigned long bytes = 0; 266 struct nfs_direct_req *dreq = hdr->dreq; 267 268 spin_lock(&dreq->lock); 269 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { 270 spin_unlock(&dreq->lock); 271 goto out_put; 272 } 273 274 nfs_direct_count_bytes(dreq, hdr); 275 spin_unlock(&dreq->lock); 276 277 while (!list_empty(&hdr->pages)) { 278 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 279 struct page *page = req->wb_page; 280 281 if (!PageCompound(page) && bytes < hdr->good_bytes && 282 (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY)) 283 set_page_dirty(page); 284 bytes += req->wb_bytes; 285 nfs_list_remove_request(req); 286 nfs_release_request(req); 287 } 288out_put: 289 if (put_dreq(dreq)) 290 nfs_direct_complete(dreq); 291 hdr->release(hdr); 292} 293 294static void nfs_read_sync_pgio_error(struct list_head *head, int error) 295{ 296 struct nfs_page *req; 297 298 while (!list_empty(head)) { 299 req = nfs_list_entry(head->next); 300 nfs_list_remove_request(req); 301 nfs_release_request(req); 302 } 303} 304 305static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr) 306{ 307 get_dreq(hdr->dreq); 308} 309 310static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = { 311 .error_cleanup = nfs_read_sync_pgio_error, 312 .init_hdr = nfs_direct_pgio_init, 313 .completion = nfs_direct_read_completion, 314}; 315 316/* 317 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ 318 * operation. If nfs_readdata_alloc() or get_user_pages() fails, 319 * bail and stop sending more reads. Read length accounting is 320 * handled automatically by nfs_direct_read_result(). Otherwise, if 321 * no requests have been sent, just return an error. 322 */ 323 324static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq, 325 struct iov_iter *iter, 326 loff_t pos) 327{ 328 struct nfs_pageio_descriptor desc; 329 struct inode *inode = dreq->inode; 330 ssize_t result = -EINVAL; 331 size_t requested_bytes = 0; 332 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE); 333 334 nfs_pageio_init_read(&desc, dreq->inode, false, 335 &nfs_direct_read_completion_ops); 336 get_dreq(dreq); 337 desc.pg_dreq = dreq; 338 inode_dio_begin(inode); 339 340 while (iov_iter_count(iter)) { 341 struct page **pagevec; 342 size_t bytes; 343 size_t pgbase; 344 unsigned npages, i; 345 346 result = iov_iter_get_pages_alloc2(iter, &pagevec, 347 rsize, &pgbase); 348 if (result < 0) 349 break; 350 351 bytes = result; 352 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 353 for (i = 0; i < npages; i++) { 354 struct nfs_page *req; 355 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 356 /* XXX do we need to do the eof zeroing found in async_filler? */ 357 req = nfs_page_create_from_page(dreq->ctx, pagevec[i], 358 pgbase, pos, req_len); 359 if (IS_ERR(req)) { 360 result = PTR_ERR(req); 361 break; 362 } 363 if (!nfs_pageio_add_request(&desc, req)) { 364 result = desc.pg_error; 365 nfs_release_request(req); 366 break; 367 } 368 pgbase = 0; 369 bytes -= req_len; 370 requested_bytes += req_len; 371 pos += req_len; 372 } 373 nfs_direct_release_pages(pagevec, npages); 374 kvfree(pagevec); 375 if (result < 0) 376 break; 377 } 378 379 nfs_pageio_complete(&desc); 380 381 /* 382 * If no bytes were started, return the error, and let the 383 * generic layer handle the completion. 384 */ 385 if (requested_bytes == 0) { 386 inode_dio_end(inode); 387 nfs_direct_req_release(dreq); 388 return result < 0 ? result : -EIO; 389 } 390 391 if (put_dreq(dreq)) 392 nfs_direct_complete(dreq); 393 return requested_bytes; 394} 395 396/** 397 * nfs_file_direct_read - file direct read operation for NFS files 398 * @iocb: target I/O control block 399 * @iter: vector of user buffers into which to read data 400 * @swap: flag indicating this is swap IO, not O_DIRECT IO 401 * 402 * We use this function for direct reads instead of calling 403 * generic_file_aio_read() in order to avoid gfar's check to see if 404 * the request starts before the end of the file. For that check 405 * to work, we must generate a GETATTR before each direct read, and 406 * even then there is a window between the GETATTR and the subsequent 407 * READ where the file size could change. Our preference is simply 408 * to do all reads the application wants, and the server will take 409 * care of managing the end of file boundary. 410 * 411 * This function also eliminates unnecessarily updating the file's 412 * atime locally, as the NFS server sets the file's atime, and this 413 * client must read the updated atime from the server back into its 414 * cache. 415 */ 416ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter, 417 bool swap) 418{ 419 struct file *file = iocb->ki_filp; 420 struct address_space *mapping = file->f_mapping; 421 struct inode *inode = mapping->host; 422 struct nfs_direct_req *dreq; 423 struct nfs_lock_context *l_ctx; 424 ssize_t result, requested; 425 size_t count = iov_iter_count(iter); 426 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count); 427 428 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n", 429 file, count, (long long) iocb->ki_pos); 430 431 result = 0; 432 if (!count) 433 goto out; 434 435 task_io_account_read(count); 436 437 result = -ENOMEM; 438 dreq = nfs_direct_req_alloc(); 439 if (dreq == NULL) 440 goto out; 441 442 dreq->inode = inode; 443 dreq->max_count = count; 444 dreq->io_start = iocb->ki_pos; 445 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 446 l_ctx = nfs_get_lock_context(dreq->ctx); 447 if (IS_ERR(l_ctx)) { 448 result = PTR_ERR(l_ctx); 449 nfs_direct_req_release(dreq); 450 goto out_release; 451 } 452 dreq->l_ctx = l_ctx; 453 if (!is_sync_kiocb(iocb)) 454 dreq->iocb = iocb; 455 456 if (user_backed_iter(iter)) 457 dreq->flags = NFS_ODIRECT_SHOULD_DIRTY; 458 459 if (!swap) 460 nfs_start_io_direct(inode); 461 462 NFS_I(inode)->read_io += count; 463 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos); 464 465 if (!swap) 466 nfs_end_io_direct(inode); 467 468 if (requested > 0) { 469 result = nfs_direct_wait(dreq); 470 if (result > 0) { 471 requested -= result; 472 iocb->ki_pos += result; 473 } 474 iov_iter_revert(iter, requested); 475 } else { 476 result = requested; 477 } 478 479out_release: 480 nfs_direct_req_release(dreq); 481out: 482 return result; 483} 484 485static void nfs_direct_add_page_head(struct list_head *list, 486 struct nfs_page *req) 487{ 488 struct nfs_page *head = req->wb_head; 489 490 if (!list_empty(&head->wb_list) || !nfs_lock_request(head)) 491 return; 492 if (!list_empty(&head->wb_list)) { 493 nfs_unlock_request(head); 494 return; 495 } 496 list_add(&head->wb_list, list); 497 kref_get(&head->wb_kref); 498 kref_get(&head->wb_kref); 499} 500 501static void nfs_direct_join_group(struct list_head *list, 502 struct nfs_commit_info *cinfo, 503 struct inode *inode) 504{ 505 struct nfs_page *req, *subreq; 506 507 list_for_each_entry(req, list, wb_list) { 508 if (req->wb_head != req) { 509 nfs_direct_add_page_head(&req->wb_list, req); 510 continue; 511 } 512 subreq = req->wb_this_page; 513 if (subreq == req) 514 continue; 515 do { 516 /* 517 * Remove subrequests from this list before freeing 518 * them in the call to nfs_join_page_group(). 519 */ 520 if (!list_empty(&subreq->wb_list)) { 521 nfs_list_remove_request(subreq); 522 nfs_release_request(subreq); 523 } 524 } while ((subreq = subreq->wb_this_page) != req); 525 nfs_join_page_group(req, cinfo, inode); 526 } 527} 528 529static void 530nfs_direct_write_scan_commit_list(struct inode *inode, 531 struct list_head *list, 532 struct nfs_commit_info *cinfo) 533{ 534 mutex_lock(&NFS_I(cinfo->inode)->commit_mutex); 535 pnfs_recover_commit_reqs(list, cinfo); 536 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0); 537 mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex); 538} 539 540static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) 541{ 542 struct nfs_pageio_descriptor desc; 543 struct nfs_page *req; 544 LIST_HEAD(reqs); 545 struct nfs_commit_info cinfo; 546 547 nfs_init_cinfo_from_dreq(&cinfo, dreq); 548 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 549 550 nfs_direct_join_group(&reqs, &cinfo, dreq->inode); 551 552 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo); 553 get_dreq(dreq); 554 555 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false, 556 &nfs_direct_write_completion_ops); 557 desc.pg_dreq = dreq; 558 559 while (!list_empty(&reqs)) { 560 req = nfs_list_entry(reqs.next); 561 /* Bump the transmission count */ 562 req->wb_nio++; 563 if (!nfs_pageio_add_request(&desc, req)) { 564 spin_lock(&dreq->lock); 565 if (dreq->error < 0) { 566 desc.pg_error = dreq->error; 567 } else if (desc.pg_error != -EAGAIN) { 568 dreq->flags = 0; 569 if (!desc.pg_error) 570 desc.pg_error = -EIO; 571 dreq->error = desc.pg_error; 572 } else 573 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 574 spin_unlock(&dreq->lock); 575 break; 576 } 577 nfs_release_request(req); 578 } 579 nfs_pageio_complete(&desc); 580 581 while (!list_empty(&reqs)) { 582 req = nfs_list_entry(reqs.next); 583 nfs_list_remove_request(req); 584 nfs_unlock_and_release_request(req); 585 if (desc.pg_error == -EAGAIN) { 586 nfs_mark_request_commit(req, NULL, &cinfo, 0); 587 } else { 588 spin_lock(&dreq->lock); 589 nfs_direct_truncate_request(dreq, req); 590 spin_unlock(&dreq->lock); 591 nfs_release_request(req); 592 } 593 } 594 595 if (put_dreq(dreq)) 596 nfs_direct_write_complete(dreq); 597} 598 599static void nfs_direct_commit_complete(struct nfs_commit_data *data) 600{ 601 const struct nfs_writeverf *verf = data->res.verf; 602 struct nfs_direct_req *dreq = data->dreq; 603 struct nfs_commit_info cinfo; 604 struct nfs_page *req; 605 int status = data->task.tk_status; 606 607 trace_nfs_direct_commit_complete(dreq); 608 609 spin_lock(&dreq->lock); 610 if (status < 0) { 611 /* Errors in commit are fatal */ 612 dreq->error = status; 613 dreq->flags = NFS_ODIRECT_DONE; 614 } else { 615 status = dreq->error; 616 } 617 spin_unlock(&dreq->lock); 618 619 nfs_init_cinfo_from_dreq(&cinfo, dreq); 620 621 while (!list_empty(&data->pages)) { 622 req = nfs_list_entry(data->pages.next); 623 nfs_list_remove_request(req); 624 if (status < 0) { 625 spin_lock(&dreq->lock); 626 nfs_direct_truncate_request(dreq, req); 627 spin_unlock(&dreq->lock); 628 nfs_release_request(req); 629 } else if (!nfs_write_match_verf(verf, req)) { 630 spin_lock(&dreq->lock); 631 if (dreq->flags == 0) 632 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 633 spin_unlock(&dreq->lock); 634 /* 635 * Despite the reboot, the write was successful, 636 * so reset wb_nio. 637 */ 638 req->wb_nio = 0; 639 nfs_mark_request_commit(req, NULL, &cinfo, 0); 640 } else 641 nfs_release_request(req); 642 nfs_unlock_and_release_request(req); 643 } 644 645 if (nfs_commit_end(cinfo.mds)) 646 nfs_direct_write_complete(dreq); 647} 648 649static void nfs_direct_resched_write(struct nfs_commit_info *cinfo, 650 struct nfs_page *req) 651{ 652 struct nfs_direct_req *dreq = cinfo->dreq; 653 654 trace_nfs_direct_resched_write(dreq); 655 656 spin_lock(&dreq->lock); 657 if (dreq->flags != NFS_ODIRECT_DONE) 658 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 659 spin_unlock(&dreq->lock); 660 nfs_mark_request_commit(req, NULL, cinfo, 0); 661} 662 663static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = { 664 .completion = nfs_direct_commit_complete, 665 .resched_write = nfs_direct_resched_write, 666}; 667 668static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) 669{ 670 int res; 671 struct nfs_commit_info cinfo; 672 LIST_HEAD(mds_list); 673 674 nfs_init_cinfo_from_dreq(&cinfo, dreq); 675 nfs_commit_begin(cinfo.mds); 676 nfs_scan_commit(dreq->inode, &mds_list, &cinfo); 677 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo); 678 if (res < 0) { /* res == -ENOMEM */ 679 spin_lock(&dreq->lock); 680 if (dreq->flags == 0) 681 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 682 spin_unlock(&dreq->lock); 683 } 684 if (nfs_commit_end(cinfo.mds)) 685 nfs_direct_write_complete(dreq); 686} 687 688static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq) 689{ 690 struct nfs_commit_info cinfo; 691 struct nfs_page *req; 692 LIST_HEAD(reqs); 693 694 nfs_init_cinfo_from_dreq(&cinfo, dreq); 695 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 696 697 while (!list_empty(&reqs)) { 698 req = nfs_list_entry(reqs.next); 699 nfs_list_remove_request(req); 700 nfs_direct_truncate_request(dreq, req); 701 nfs_release_request(req); 702 nfs_unlock_and_release_request(req); 703 } 704} 705 706static void nfs_direct_write_schedule_work(struct work_struct *work) 707{ 708 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work); 709 int flags = dreq->flags; 710 711 dreq->flags = 0; 712 switch (flags) { 713 case NFS_ODIRECT_DO_COMMIT: 714 nfs_direct_commit_schedule(dreq); 715 break; 716 case NFS_ODIRECT_RESCHED_WRITES: 717 nfs_direct_write_reschedule(dreq); 718 break; 719 default: 720 nfs_direct_write_clear_reqs(dreq); 721 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping); 722 nfs_direct_complete(dreq); 723 } 724} 725 726static void nfs_direct_write_complete(struct nfs_direct_req *dreq) 727{ 728 trace_nfs_direct_write_complete(dreq); 729 queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */ 730} 731 732static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) 733{ 734 struct nfs_direct_req *dreq = hdr->dreq; 735 struct nfs_commit_info cinfo; 736 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 737 int flags = NFS_ODIRECT_DONE; 738 739 trace_nfs_direct_write_completion(dreq); 740 741 nfs_init_cinfo_from_dreq(&cinfo, dreq); 742 743 spin_lock(&dreq->lock); 744 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { 745 spin_unlock(&dreq->lock); 746 goto out_put; 747 } 748 749 nfs_direct_count_bytes(dreq, hdr); 750 if (test_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags) && 751 !test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 752 if (!dreq->flags) 753 dreq->flags = NFS_ODIRECT_DO_COMMIT; 754 flags = dreq->flags; 755 } 756 spin_unlock(&dreq->lock); 757 758 while (!list_empty(&hdr->pages)) { 759 760 req = nfs_list_entry(hdr->pages.next); 761 nfs_list_remove_request(req); 762 if (flags == NFS_ODIRECT_DO_COMMIT) { 763 kref_get(&req->wb_kref); 764 memcpy(&req->wb_verf, &hdr->verf.verifier, 765 sizeof(req->wb_verf)); 766 nfs_mark_request_commit(req, hdr->lseg, &cinfo, 767 hdr->ds_commit_idx); 768 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) { 769 kref_get(&req->wb_kref); 770 nfs_mark_request_commit(req, NULL, &cinfo, 0); 771 } 772 nfs_unlock_and_release_request(req); 773 } 774 775out_put: 776 if (put_dreq(dreq)) 777 nfs_direct_write_complete(dreq); 778 hdr->release(hdr); 779} 780 781static void nfs_write_sync_pgio_error(struct list_head *head, int error) 782{ 783 struct nfs_page *req; 784 785 while (!list_empty(head)) { 786 req = nfs_list_entry(head->next); 787 nfs_list_remove_request(req); 788 nfs_unlock_and_release_request(req); 789 } 790} 791 792static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr) 793{ 794 struct nfs_direct_req *dreq = hdr->dreq; 795 struct nfs_page *req; 796 struct nfs_commit_info cinfo; 797 798 trace_nfs_direct_write_reschedule_io(dreq); 799 800 nfs_init_cinfo_from_dreq(&cinfo, dreq); 801 spin_lock(&dreq->lock); 802 if (dreq->error == 0) 803 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 804 set_bit(NFS_IOHDR_REDO, &hdr->flags); 805 spin_unlock(&dreq->lock); 806 while (!list_empty(&hdr->pages)) { 807 req = nfs_list_entry(hdr->pages.next); 808 nfs_list_remove_request(req); 809 nfs_unlock_request(req); 810 nfs_mark_request_commit(req, NULL, &cinfo, 0); 811 } 812} 813 814static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = { 815 .error_cleanup = nfs_write_sync_pgio_error, 816 .init_hdr = nfs_direct_pgio_init, 817 .completion = nfs_direct_write_completion, 818 .reschedule_io = nfs_direct_write_reschedule_io, 819}; 820 821 822/* 823 * NB: Return the value of the first error return code. Subsequent 824 * errors after the first one are ignored. 825 */ 826/* 827 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE 828 * operation. If nfs_writedata_alloc() or get_user_pages() fails, 829 * bail and stop sending more writes. Write length accounting is 830 * handled automatically by nfs_direct_write_result(). Otherwise, if 831 * no requests have been sent, just return an error. 832 */ 833static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq, 834 struct iov_iter *iter, 835 loff_t pos, int ioflags) 836{ 837 struct nfs_pageio_descriptor desc; 838 struct inode *inode = dreq->inode; 839 struct nfs_commit_info cinfo; 840 ssize_t result = 0; 841 size_t requested_bytes = 0; 842 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE); 843 bool defer = false; 844 845 trace_nfs_direct_write_schedule_iovec(dreq); 846 847 nfs_pageio_init_write(&desc, inode, ioflags, false, 848 &nfs_direct_write_completion_ops); 849 desc.pg_dreq = dreq; 850 get_dreq(dreq); 851 inode_dio_begin(inode); 852 853 NFS_I(inode)->write_io += iov_iter_count(iter); 854 while (iov_iter_count(iter)) { 855 struct page **pagevec; 856 size_t bytes; 857 size_t pgbase; 858 unsigned npages, i; 859 860 result = iov_iter_get_pages_alloc2(iter, &pagevec, 861 wsize, &pgbase); 862 if (result < 0) 863 break; 864 865 bytes = result; 866 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 867 for (i = 0; i < npages; i++) { 868 struct nfs_page *req; 869 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 870 871 req = nfs_page_create_from_page(dreq->ctx, pagevec[i], 872 pgbase, pos, req_len); 873 if (IS_ERR(req)) { 874 result = PTR_ERR(req); 875 break; 876 } 877 878 if (desc.pg_error < 0) { 879 nfs_free_request(req); 880 result = desc.pg_error; 881 break; 882 } 883 884 pgbase = 0; 885 bytes -= req_len; 886 requested_bytes += req_len; 887 pos += req_len; 888 889 if (defer) { 890 nfs_mark_request_commit(req, NULL, &cinfo, 0); 891 continue; 892 } 893 894 nfs_lock_request(req); 895 if (nfs_pageio_add_request(&desc, req)) 896 continue; 897 898 /* Exit on hard errors */ 899 if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) { 900 result = desc.pg_error; 901 nfs_unlock_and_release_request(req); 902 break; 903 } 904 905 /* If the error is soft, defer remaining requests */ 906 nfs_init_cinfo_from_dreq(&cinfo, dreq); 907 spin_lock(&dreq->lock); 908 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 909 spin_unlock(&dreq->lock); 910 nfs_unlock_request(req); 911 nfs_mark_request_commit(req, NULL, &cinfo, 0); 912 desc.pg_error = 0; 913 defer = true; 914 } 915 nfs_direct_release_pages(pagevec, npages); 916 kvfree(pagevec); 917 if (result < 0) 918 break; 919 } 920 nfs_pageio_complete(&desc); 921 922 /* 923 * If no bytes were started, return the error, and let the 924 * generic layer handle the completion. 925 */ 926 if (requested_bytes == 0) { 927 inode_dio_end(inode); 928 nfs_direct_req_release(dreq); 929 return result < 0 ? result : -EIO; 930 } 931 932 if (put_dreq(dreq)) 933 nfs_direct_write_complete(dreq); 934 return requested_bytes; 935} 936 937/** 938 * nfs_file_direct_write - file direct write operation for NFS files 939 * @iocb: target I/O control block 940 * @iter: vector of user buffers from which to write data 941 * @swap: flag indicating this is swap IO, not O_DIRECT IO 942 * 943 * We use this function for direct writes instead of calling 944 * generic_file_aio_write() in order to avoid taking the inode 945 * semaphore and updating the i_size. The NFS server will set 946 * the new i_size and this client must read the updated size 947 * back into its cache. We let the server do generic write 948 * parameter checking and report problems. 949 * 950 * We eliminate local atime updates, see direct read above. 951 * 952 * We avoid unnecessary page cache invalidations for normal cached 953 * readers of this file. 954 * 955 * Note that O_APPEND is not supported for NFS direct writes, as there 956 * is no atomic O_APPEND write facility in the NFS protocol. 957 */ 958ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter, 959 bool swap) 960{ 961 ssize_t result, requested; 962 size_t count; 963 struct file *file = iocb->ki_filp; 964 struct address_space *mapping = file->f_mapping; 965 struct inode *inode = mapping->host; 966 struct nfs_direct_req *dreq; 967 struct nfs_lock_context *l_ctx; 968 loff_t pos, end; 969 970 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", 971 file, iov_iter_count(iter), (long long) iocb->ki_pos); 972 973 if (swap) 974 /* bypass generic checks */ 975 result = iov_iter_count(iter); 976 else 977 result = generic_write_checks(iocb, iter); 978 if (result <= 0) 979 return result; 980 count = result; 981 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count); 982 983 pos = iocb->ki_pos; 984 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT; 985 986 task_io_account_write(count); 987 988 result = -ENOMEM; 989 dreq = nfs_direct_req_alloc(); 990 if (!dreq) 991 goto out; 992 993 dreq->inode = inode; 994 dreq->max_count = count; 995 dreq->io_start = pos; 996 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 997 l_ctx = nfs_get_lock_context(dreq->ctx); 998 if (IS_ERR(l_ctx)) { 999 result = PTR_ERR(l_ctx); 1000 nfs_direct_req_release(dreq); 1001 goto out_release; 1002 } 1003 dreq->l_ctx = l_ctx; 1004 if (!is_sync_kiocb(iocb)) 1005 dreq->iocb = iocb; 1006 pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode); 1007 1008 if (swap) { 1009 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos, 1010 FLUSH_STABLE); 1011 } else { 1012 nfs_start_io_direct(inode); 1013 1014 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos, 1015 FLUSH_COND_STABLE); 1016 1017 if (mapping->nrpages) { 1018 invalidate_inode_pages2_range(mapping, 1019 pos >> PAGE_SHIFT, end); 1020 } 1021 1022 nfs_end_io_direct(inode); 1023 } 1024 1025 if (requested > 0) { 1026 result = nfs_direct_wait(dreq); 1027 if (result > 0) { 1028 requested -= result; 1029 iocb->ki_pos = pos + result; 1030 /* XXX: should check the generic_write_sync retval */ 1031 generic_write_sync(iocb, result); 1032 } 1033 iov_iter_revert(iter, requested); 1034 } else { 1035 result = requested; 1036 } 1037 nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE); 1038out_release: 1039 nfs_direct_req_release(dreq); 1040out: 1041 return result; 1042} 1043 1044/** 1045 * nfs_init_directcache - create a slab cache for nfs_direct_req structures 1046 * 1047 */ 1048int __init nfs_init_directcache(void) 1049{ 1050 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache", 1051 sizeof(struct nfs_direct_req), 1052 0, SLAB_RECLAIM_ACCOUNT, 1053 NULL); 1054 if (nfs_direct_cachep == NULL) 1055 return -ENOMEM; 1056 1057 return 0; 1058} 1059 1060/** 1061 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures 1062 * 1063 */ 1064void nfs_destroy_directcache(void) 1065{ 1066 kmem_cache_destroy(nfs_direct_cachep); 1067} 1068