1 /* 2 * linux/fs/nfs/direct.c 3 * 4 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com> 5 * 6 * High-performance uncached I/O for the Linux NFS client 7 * 8 * There are important applications whose performance or correctness 9 * depends on uncached access to file data. Database clusters 10 * (multiple copies of the same instance running on separate hosts) 11 * implement their own cache coherency protocol that subsumes file 12 * system cache protocols. Applications that process datasets 13 * considerably larger than the client's memory do not always benefit 14 * from a local cache. A streaming video server, for instance, has no 15 * need to cache the contents of a file. 16 * 17 * When an application requests uncached I/O, all read and write requests 18 * are made directly to the server; data stored or fetched via these 19 * requests is not cached in the Linux page cache. The client does not 20 * correct unaligned requests from applications. All requested bytes are 21 * held on permanent storage before a direct write system call returns to 22 * an application. 23 * 24 * Solaris implements an uncached I/O facility called directio() that 25 * is used for backups and sequential I/O to very large files. Solaris 26 * also supports uncaching whole NFS partitions with "-o forcedirectio," 27 * an undocumented mount option. 28 * 29 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with 30 * help from Andrew Morton. 31 * 32 * 18 Dec 2001 Initial implementation for 2.4 --cel 33 * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy 34 * 08 Jun 2003 Port to 2.5 APIs --cel 35 * 31 Mar 2004 Handle direct I/O without VFS support --cel 36 * 15 Sep 2004 Parallel async reads --cel 37 * 04 May 2005 support O_DIRECT with aio --cel 38 * 39 */ 40 41 #include <linux/errno.h> 42 #include <linux/sched.h> 43 #include <linux/kernel.h> 44 #include <linux/file.h> 45 #include <linux/pagemap.h> 46 #include <linux/kref.h> 47 #include <linux/slab.h> 48 #include <linux/task_io_accounting_ops.h> 49 #include <linux/module.h> 50 51 #include <linux/nfs_fs.h> 52 #include <linux/nfs_page.h> 53 #include <linux/sunrpc/clnt.h> 54 55 #include <asm/uaccess.h> 56 #include <linux/atomic.h> 57 58 #include "internal.h" 59 #include "iostat.h" 60 #include "pnfs.h" 61 62 #define NFSDBG_FACILITY NFSDBG_VFS 63 64 static struct kmem_cache *nfs_direct_cachep; 65 66 /* 67 * This represents a set of asynchronous requests that we're waiting on 68 */ 69 struct nfs_direct_mirror { 70 ssize_t count; 71 }; 72 73 struct nfs_direct_req { 74 struct kref kref; /* release manager */ 75 76 /* I/O parameters */ 77 struct nfs_open_context *ctx; /* file open context info */ 78 struct nfs_lock_context *l_ctx; /* Lock context info */ 79 struct kiocb * iocb; /* controlling i/o request */ 80 struct inode * inode; /* target file of i/o */ 81 82 /* completion state */ 83 atomic_t io_count; /* i/os we're waiting for */ 84 spinlock_t lock; /* protect completion state */ 85 86 struct nfs_direct_mirror mirrors[NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX]; 87 int mirror_count; 88 89 ssize_t count, /* bytes actually processed */ 90 bytes_left, /* bytes left to be sent */ 91 io_start, /* start of IO */ 92 error; /* any reported error */ 93 struct completion completion; /* wait for i/o completion */ 94 95 /* commit state */ 96 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */ 97 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */ 98 struct work_struct work; 99 int flags; 100 #define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */ 101 #define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */ 102 struct nfs_writeverf verf; /* unstable write verifier */ 103 }; 104 105 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops; 106 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops; 107 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode); 108 static void nfs_direct_write_schedule_work(struct work_struct *work); 109 110 static inline void get_dreq(struct nfs_direct_req *dreq) 111 { 112 atomic_inc(&dreq->io_count); 113 } 114 115 static inline int put_dreq(struct nfs_direct_req *dreq) 116 { 117 return atomic_dec_and_test(&dreq->io_count); 118 } 119 120 static void 121 nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr) 122 { 123 int i; 124 ssize_t count; 125 126 if (dreq->mirror_count == 1) { 127 dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes; 128 dreq->count += hdr->good_bytes; 129 } else { 130 /* mirrored writes */ 131 count = dreq->mirrors[hdr->pgio_mirror_idx].count; 132 if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) { 133 count = hdr->io_start + hdr->good_bytes - dreq->io_start; 134 dreq->mirrors[hdr->pgio_mirror_idx].count = count; 135 } 136 /* update the dreq->count by finding the minimum agreed count from all 137 * mirrors */ 138 count = dreq->mirrors[0].count; 139 140 for (i = 1; i < dreq->mirror_count; i++) 141 count = min(count, dreq->mirrors[i].count); 142 143 dreq->count = count; 144 } 145 } 146 147 /* 148 * nfs_direct_select_verf - select the right verifier 149 * @dreq - direct request possibly spanning multiple servers 150 * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs 151 * @commit_idx - commit bucket index for the DS 152 * 153 * returns the correct verifier to use given the role of the server 154 */ 155 static struct nfs_writeverf * 156 nfs_direct_select_verf(struct nfs_direct_req *dreq, 157 struct nfs_client *ds_clp, 158 int commit_idx) 159 { 160 struct nfs_writeverf *verfp = &dreq->verf; 161 162 #ifdef CONFIG_NFS_V4_1 163 /* 164 * pNFS is in use, use the DS verf except commit_through_mds is set 165 * for layout segment where nbuckets is zero. 166 */ 167 if (ds_clp && dreq->ds_cinfo.nbuckets > 0) { 168 if (commit_idx >= 0 && commit_idx < dreq->ds_cinfo.nbuckets) 169 verfp = &dreq->ds_cinfo.buckets[commit_idx].direct_verf; 170 else 171 WARN_ON_ONCE(1); 172 } 173 #endif 174 return verfp; 175 } 176 177 178 /* 179 * nfs_direct_set_hdr_verf - set the write/commit verifier 180 * @dreq - direct request possibly spanning multiple servers 181 * @hdr - pageio header to validate against previously seen verfs 182 * 183 * Set the server's (MDS or DS) "seen" verifier 184 */ 185 static void nfs_direct_set_hdr_verf(struct nfs_direct_req *dreq, 186 struct nfs_pgio_header *hdr) 187 { 188 struct nfs_writeverf *verfp; 189 190 verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx); 191 WARN_ON_ONCE(verfp->committed >= 0); 192 memcpy(verfp, &hdr->verf, sizeof(struct nfs_writeverf)); 193 WARN_ON_ONCE(verfp->committed < 0); 194 } 195 196 /* 197 * nfs_direct_cmp_hdr_verf - compare verifier for pgio header 198 * @dreq - direct request possibly spanning multiple servers 199 * @hdr - pageio header to validate against previously seen verf 200 * 201 * set the server's "seen" verf if not initialized. 202 * returns result of comparison between @hdr->verf and the "seen" 203 * verf of the server used by @hdr (DS or MDS) 204 */ 205 static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq, 206 struct nfs_pgio_header *hdr) 207 { 208 struct nfs_writeverf *verfp; 209 210 verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx); 211 if (verfp->committed < 0) { 212 nfs_direct_set_hdr_verf(dreq, hdr); 213 return 0; 214 } 215 return memcmp(verfp, &hdr->verf, sizeof(struct nfs_writeverf)); 216 } 217 218 /* 219 * nfs_direct_cmp_commit_data_verf - compare verifier for commit data 220 * @dreq - direct request possibly spanning multiple servers 221 * @data - commit data to validate against previously seen verf 222 * 223 * returns result of comparison between @data->verf and the verf of 224 * the server used by @data (DS or MDS) 225 */ 226 static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq, 227 struct nfs_commit_data *data) 228 { 229 struct nfs_writeverf *verfp; 230 231 verfp = nfs_direct_select_verf(dreq, data->ds_clp, 232 data->ds_commit_index); 233 234 /* verifier not set so always fail */ 235 if (verfp->committed < 0) 236 return 1; 237 238 return memcmp(verfp, &data->verf, sizeof(struct nfs_writeverf)); 239 } 240 241 /** 242 * nfs_direct_IO - NFS address space operation for direct I/O 243 * @iocb: target I/O control block 244 * @iov: array of vectors that define I/O buffer 245 * @pos: offset in file to begin the operation 246 * @nr_segs: size of iovec array 247 * 248 * The presence of this routine in the address space ops vector means 249 * the NFS client supports direct I/O. However, for most direct IO, we 250 * shunt off direct read and write requests before the VFS gets them, 251 * so this method is only ever called for swap. 252 */ 253 ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t pos) 254 { 255 struct inode *inode = iocb->ki_filp->f_mapping->host; 256 257 /* we only support swap file calling nfs_direct_IO */ 258 if (!IS_SWAPFILE(inode)) 259 return 0; 260 261 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE); 262 263 if (iov_iter_rw(iter) == READ) 264 return nfs_file_direct_read(iocb, iter, pos); 265 return nfs_file_direct_write(iocb, iter); 266 } 267 268 static void nfs_direct_release_pages(struct page **pages, unsigned int npages) 269 { 270 unsigned int i; 271 for (i = 0; i < npages; i++) 272 page_cache_release(pages[i]); 273 } 274 275 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo, 276 struct nfs_direct_req *dreq) 277 { 278 cinfo->lock = &dreq->inode->i_lock; 279 cinfo->mds = &dreq->mds_cinfo; 280 cinfo->ds = &dreq->ds_cinfo; 281 cinfo->dreq = dreq; 282 cinfo->completion_ops = &nfs_direct_commit_completion_ops; 283 } 284 285 static inline void nfs_direct_setup_mirroring(struct nfs_direct_req *dreq, 286 struct nfs_pageio_descriptor *pgio, 287 struct nfs_page *req) 288 { 289 int mirror_count = 1; 290 291 if (pgio->pg_ops->pg_get_mirror_count) 292 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req); 293 294 dreq->mirror_count = mirror_count; 295 } 296 297 static inline struct nfs_direct_req *nfs_direct_req_alloc(void) 298 { 299 struct nfs_direct_req *dreq; 300 301 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL); 302 if (!dreq) 303 return NULL; 304 305 kref_init(&dreq->kref); 306 kref_get(&dreq->kref); 307 init_completion(&dreq->completion); 308 INIT_LIST_HEAD(&dreq->mds_cinfo.list); 309 dreq->verf.committed = NFS_INVALID_STABLE_HOW; /* not set yet */ 310 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work); 311 dreq->mirror_count = 1; 312 spin_lock_init(&dreq->lock); 313 314 return dreq; 315 } 316 317 static void nfs_direct_req_free(struct kref *kref) 318 { 319 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref); 320 321 nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo); 322 if (dreq->l_ctx != NULL) 323 nfs_put_lock_context(dreq->l_ctx); 324 if (dreq->ctx != NULL) 325 put_nfs_open_context(dreq->ctx); 326 kmem_cache_free(nfs_direct_cachep, dreq); 327 } 328 329 static void nfs_direct_req_release(struct nfs_direct_req *dreq) 330 { 331 kref_put(&dreq->kref, nfs_direct_req_free); 332 } 333 334 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq) 335 { 336 return dreq->bytes_left; 337 } 338 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left); 339 340 /* 341 * Collects and returns the final error value/byte-count. 342 */ 343 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq) 344 { 345 ssize_t result = -EIOCBQUEUED; 346 347 /* Async requests don't wait here */ 348 if (dreq->iocb) 349 goto out; 350 351 result = wait_for_completion_killable(&dreq->completion); 352 353 if (!result) 354 result = dreq->error; 355 if (!result) 356 result = dreq->count; 357 358 out: 359 return (ssize_t) result; 360 } 361 362 /* 363 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust 364 * the iocb is still valid here if this is a synchronous request. 365 */ 366 static void nfs_direct_complete(struct nfs_direct_req *dreq, bool write) 367 { 368 struct inode *inode = dreq->inode; 369 370 if (dreq->iocb && write) { 371 loff_t pos = dreq->iocb->ki_pos + dreq->count; 372 373 spin_lock(&inode->i_lock); 374 if (i_size_read(inode) < pos) 375 i_size_write(inode, pos); 376 spin_unlock(&inode->i_lock); 377 } 378 379 if (write) 380 nfs_zap_mapping(inode, inode->i_mapping); 381 382 inode_dio_end(inode); 383 384 if (dreq->iocb) { 385 long res = (long) dreq->error; 386 if (!res) 387 res = (long) dreq->count; 388 dreq->iocb->ki_complete(dreq->iocb, res, 0); 389 } 390 391 complete_all(&dreq->completion); 392 393 nfs_direct_req_release(dreq); 394 } 395 396 static void nfs_direct_readpage_release(struct nfs_page *req) 397 { 398 dprintk("NFS: direct read done (%s/%llu %d@%lld)\n", 399 d_inode(req->wb_context->dentry)->i_sb->s_id, 400 (unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)), 401 req->wb_bytes, 402 (long long)req_offset(req)); 403 nfs_release_request(req); 404 } 405 406 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) 407 { 408 unsigned long bytes = 0; 409 struct nfs_direct_req *dreq = hdr->dreq; 410 411 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 412 goto out_put; 413 414 spin_lock(&dreq->lock); 415 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0)) 416 dreq->error = hdr->error; 417 else 418 nfs_direct_good_bytes(dreq, hdr); 419 420 spin_unlock(&dreq->lock); 421 422 while (!list_empty(&hdr->pages)) { 423 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 424 struct page *page = req->wb_page; 425 426 if (!PageCompound(page) && bytes < hdr->good_bytes) 427 set_page_dirty(page); 428 bytes += req->wb_bytes; 429 nfs_list_remove_request(req); 430 nfs_direct_readpage_release(req); 431 } 432 out_put: 433 if (put_dreq(dreq)) 434 nfs_direct_complete(dreq, false); 435 hdr->release(hdr); 436 } 437 438 static void nfs_read_sync_pgio_error(struct list_head *head) 439 { 440 struct nfs_page *req; 441 442 while (!list_empty(head)) { 443 req = nfs_list_entry(head->next); 444 nfs_list_remove_request(req); 445 nfs_release_request(req); 446 } 447 } 448 449 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr) 450 { 451 get_dreq(hdr->dreq); 452 } 453 454 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = { 455 .error_cleanup = nfs_read_sync_pgio_error, 456 .init_hdr = nfs_direct_pgio_init, 457 .completion = nfs_direct_read_completion, 458 }; 459 460 /* 461 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ 462 * operation. If nfs_readdata_alloc() or get_user_pages() fails, 463 * bail and stop sending more reads. Read length accounting is 464 * handled automatically by nfs_direct_read_result(). Otherwise, if 465 * no requests have been sent, just return an error. 466 */ 467 468 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq, 469 struct iov_iter *iter, 470 loff_t pos) 471 { 472 struct nfs_pageio_descriptor desc; 473 struct inode *inode = dreq->inode; 474 ssize_t result = -EINVAL; 475 size_t requested_bytes = 0; 476 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE); 477 478 nfs_pageio_init_read(&desc, dreq->inode, false, 479 &nfs_direct_read_completion_ops); 480 get_dreq(dreq); 481 desc.pg_dreq = dreq; 482 inode_dio_begin(inode); 483 484 while (iov_iter_count(iter)) { 485 struct page **pagevec; 486 size_t bytes; 487 size_t pgbase; 488 unsigned npages, i; 489 490 result = iov_iter_get_pages_alloc(iter, &pagevec, 491 rsize, &pgbase); 492 if (result < 0) 493 break; 494 495 bytes = result; 496 iov_iter_advance(iter, bytes); 497 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 498 for (i = 0; i < npages; i++) { 499 struct nfs_page *req; 500 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 501 /* XXX do we need to do the eof zeroing found in async_filler? */ 502 req = nfs_create_request(dreq->ctx, pagevec[i], NULL, 503 pgbase, req_len); 504 if (IS_ERR(req)) { 505 result = PTR_ERR(req); 506 break; 507 } 508 req->wb_index = pos >> PAGE_SHIFT; 509 req->wb_offset = pos & ~PAGE_MASK; 510 if (!nfs_pageio_add_request(&desc, req)) { 511 result = desc.pg_error; 512 nfs_release_request(req); 513 break; 514 } 515 pgbase = 0; 516 bytes -= req_len; 517 requested_bytes += req_len; 518 pos += req_len; 519 dreq->bytes_left -= req_len; 520 } 521 nfs_direct_release_pages(pagevec, npages); 522 kvfree(pagevec); 523 if (result < 0) 524 break; 525 } 526 527 nfs_pageio_complete(&desc); 528 529 /* 530 * If no bytes were started, return the error, and let the 531 * generic layer handle the completion. 532 */ 533 if (requested_bytes == 0) { 534 inode_dio_end(inode); 535 nfs_direct_req_release(dreq); 536 return result < 0 ? result : -EIO; 537 } 538 539 if (put_dreq(dreq)) 540 nfs_direct_complete(dreq, false); 541 return 0; 542 } 543 544 /** 545 * nfs_file_direct_read - file direct read operation for NFS files 546 * @iocb: target I/O control block 547 * @iter: vector of user buffers into which to read data 548 * @pos: byte offset in file where reading starts 549 * 550 * We use this function for direct reads instead of calling 551 * generic_file_aio_read() in order to avoid gfar's check to see if 552 * the request starts before the end of the file. For that check 553 * to work, we must generate a GETATTR before each direct read, and 554 * even then there is a window between the GETATTR and the subsequent 555 * READ where the file size could change. Our preference is simply 556 * to do all reads the application wants, and the server will take 557 * care of managing the end of file boundary. 558 * 559 * This function also eliminates unnecessarily updating the file's 560 * atime locally, as the NFS server sets the file's atime, and this 561 * client must read the updated atime from the server back into its 562 * cache. 563 */ 564 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter, 565 loff_t pos) 566 { 567 struct file *file = iocb->ki_filp; 568 struct address_space *mapping = file->f_mapping; 569 struct inode *inode = mapping->host; 570 struct nfs_direct_req *dreq; 571 struct nfs_lock_context *l_ctx; 572 ssize_t result = -EINVAL; 573 size_t count = iov_iter_count(iter); 574 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count); 575 576 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n", 577 file, count, (long long) pos); 578 579 result = 0; 580 if (!count) 581 goto out; 582 583 inode_lock(inode); 584 result = nfs_sync_mapping(mapping); 585 if (result) 586 goto out_unlock; 587 588 task_io_account_read(count); 589 590 result = -ENOMEM; 591 dreq = nfs_direct_req_alloc(); 592 if (dreq == NULL) 593 goto out_unlock; 594 595 dreq->inode = inode; 596 dreq->bytes_left = count; 597 dreq->io_start = pos; 598 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 599 l_ctx = nfs_get_lock_context(dreq->ctx); 600 if (IS_ERR(l_ctx)) { 601 result = PTR_ERR(l_ctx); 602 goto out_release; 603 } 604 dreq->l_ctx = l_ctx; 605 if (!is_sync_kiocb(iocb)) 606 dreq->iocb = iocb; 607 608 NFS_I(inode)->read_io += count; 609 result = nfs_direct_read_schedule_iovec(dreq, iter, pos); 610 611 inode_unlock(inode); 612 613 if (!result) { 614 result = nfs_direct_wait(dreq); 615 if (result > 0) 616 iocb->ki_pos = pos + result; 617 } 618 619 nfs_direct_req_release(dreq); 620 return result; 621 622 out_release: 623 nfs_direct_req_release(dreq); 624 out_unlock: 625 inode_unlock(inode); 626 out: 627 return result; 628 } 629 630 static void 631 nfs_direct_write_scan_commit_list(struct inode *inode, 632 struct list_head *list, 633 struct nfs_commit_info *cinfo) 634 { 635 spin_lock(cinfo->lock); 636 #ifdef CONFIG_NFS_V4_1 637 if (cinfo->ds != NULL && cinfo->ds->nwritten != 0) 638 NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo); 639 #endif 640 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0); 641 spin_unlock(cinfo->lock); 642 } 643 644 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) 645 { 646 struct nfs_pageio_descriptor desc; 647 struct nfs_page *req, *tmp; 648 LIST_HEAD(reqs); 649 struct nfs_commit_info cinfo; 650 LIST_HEAD(failed); 651 int i; 652 653 nfs_init_cinfo_from_dreq(&cinfo, dreq); 654 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 655 656 dreq->count = 0; 657 for (i = 0; i < dreq->mirror_count; i++) 658 dreq->mirrors[i].count = 0; 659 get_dreq(dreq); 660 661 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false, 662 &nfs_direct_write_completion_ops); 663 desc.pg_dreq = dreq; 664 665 req = nfs_list_entry(reqs.next); 666 nfs_direct_setup_mirroring(dreq, &desc, req); 667 if (desc.pg_error < 0) { 668 list_splice_init(&reqs, &failed); 669 goto out_failed; 670 } 671 672 list_for_each_entry_safe(req, tmp, &reqs, wb_list) { 673 if (!nfs_pageio_add_request(&desc, req)) { 674 nfs_list_remove_request(req); 675 nfs_list_add_request(req, &failed); 676 spin_lock(cinfo.lock); 677 dreq->flags = 0; 678 if (desc.pg_error < 0) 679 dreq->error = desc.pg_error; 680 else 681 dreq->error = -EIO; 682 spin_unlock(cinfo.lock); 683 } 684 nfs_release_request(req); 685 } 686 nfs_pageio_complete(&desc); 687 688 out_failed: 689 while (!list_empty(&failed)) { 690 req = nfs_list_entry(failed.next); 691 nfs_list_remove_request(req); 692 nfs_unlock_and_release_request(req); 693 } 694 695 if (put_dreq(dreq)) 696 nfs_direct_write_complete(dreq, dreq->inode); 697 } 698 699 static void nfs_direct_commit_complete(struct nfs_commit_data *data) 700 { 701 struct nfs_direct_req *dreq = data->dreq; 702 struct nfs_commit_info cinfo; 703 struct nfs_page *req; 704 int status = data->task.tk_status; 705 706 nfs_init_cinfo_from_dreq(&cinfo, dreq); 707 if (status < 0) { 708 dprintk("NFS: %5u commit failed with error %d.\n", 709 data->task.tk_pid, status); 710 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 711 } else if (nfs_direct_cmp_commit_data_verf(dreq, data)) { 712 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid); 713 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 714 } 715 716 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status); 717 while (!list_empty(&data->pages)) { 718 req = nfs_list_entry(data->pages.next); 719 nfs_list_remove_request(req); 720 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) { 721 /* Note the rewrite will go through mds */ 722 nfs_mark_request_commit(req, NULL, &cinfo, 0); 723 } else 724 nfs_release_request(req); 725 nfs_unlock_and_release_request(req); 726 } 727 728 if (atomic_dec_and_test(&cinfo.mds->rpcs_out)) 729 nfs_direct_write_complete(dreq, data->inode); 730 } 731 732 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo, 733 struct nfs_page *req) 734 { 735 struct nfs_direct_req *dreq = cinfo->dreq; 736 737 spin_lock(&dreq->lock); 738 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 739 spin_unlock(&dreq->lock); 740 nfs_mark_request_commit(req, NULL, cinfo, 0); 741 } 742 743 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = { 744 .completion = nfs_direct_commit_complete, 745 .resched_write = nfs_direct_resched_write, 746 }; 747 748 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) 749 { 750 int res; 751 struct nfs_commit_info cinfo; 752 LIST_HEAD(mds_list); 753 754 nfs_init_cinfo_from_dreq(&cinfo, dreq); 755 nfs_scan_commit(dreq->inode, &mds_list, &cinfo); 756 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo); 757 if (res < 0) /* res == -ENOMEM */ 758 nfs_direct_write_reschedule(dreq); 759 } 760 761 static void nfs_direct_write_schedule_work(struct work_struct *work) 762 { 763 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work); 764 int flags = dreq->flags; 765 766 dreq->flags = 0; 767 switch (flags) { 768 case NFS_ODIRECT_DO_COMMIT: 769 nfs_direct_commit_schedule(dreq); 770 break; 771 case NFS_ODIRECT_RESCHED_WRITES: 772 nfs_direct_write_reschedule(dreq); 773 break; 774 default: 775 nfs_direct_complete(dreq, true); 776 } 777 } 778 779 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode) 780 { 781 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */ 782 } 783 784 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) 785 { 786 struct nfs_direct_req *dreq = hdr->dreq; 787 struct nfs_commit_info cinfo; 788 bool request_commit = false; 789 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 790 791 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 792 goto out_put; 793 794 nfs_init_cinfo_from_dreq(&cinfo, dreq); 795 796 spin_lock(&dreq->lock); 797 798 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 799 dreq->flags = 0; 800 dreq->error = hdr->error; 801 } 802 if (dreq->error == 0) { 803 nfs_direct_good_bytes(dreq, hdr); 804 if (nfs_write_need_commit(hdr)) { 805 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) 806 request_commit = true; 807 else if (dreq->flags == 0) { 808 nfs_direct_set_hdr_verf(dreq, hdr); 809 request_commit = true; 810 dreq->flags = NFS_ODIRECT_DO_COMMIT; 811 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) { 812 request_commit = true; 813 if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr)) 814 dreq->flags = 815 NFS_ODIRECT_RESCHED_WRITES; 816 } 817 } 818 } 819 spin_unlock(&dreq->lock); 820 821 while (!list_empty(&hdr->pages)) { 822 823 req = nfs_list_entry(hdr->pages.next); 824 nfs_list_remove_request(req); 825 if (request_commit) { 826 kref_get(&req->wb_kref); 827 nfs_mark_request_commit(req, hdr->lseg, &cinfo, 828 hdr->ds_commit_idx); 829 } 830 nfs_unlock_and_release_request(req); 831 } 832 833 out_put: 834 if (put_dreq(dreq)) 835 nfs_direct_write_complete(dreq, hdr->inode); 836 hdr->release(hdr); 837 } 838 839 static void nfs_write_sync_pgio_error(struct list_head *head) 840 { 841 struct nfs_page *req; 842 843 while (!list_empty(head)) { 844 req = nfs_list_entry(head->next); 845 nfs_list_remove_request(req); 846 nfs_unlock_and_release_request(req); 847 } 848 } 849 850 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr) 851 { 852 struct nfs_direct_req *dreq = hdr->dreq; 853 854 spin_lock(&dreq->lock); 855 if (dreq->error == 0) { 856 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 857 /* fake unstable write to let common nfs resend pages */ 858 hdr->verf.committed = NFS_UNSTABLE; 859 hdr->good_bytes = hdr->args.count; 860 } 861 spin_unlock(&dreq->lock); 862 } 863 864 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = { 865 .error_cleanup = nfs_write_sync_pgio_error, 866 .init_hdr = nfs_direct_pgio_init, 867 .completion = nfs_direct_write_completion, 868 .reschedule_io = nfs_direct_write_reschedule_io, 869 }; 870 871 872 /* 873 * NB: Return the value of the first error return code. Subsequent 874 * errors after the first one are ignored. 875 */ 876 /* 877 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE 878 * operation. If nfs_writedata_alloc() or get_user_pages() fails, 879 * bail and stop sending more writes. Write length accounting is 880 * handled automatically by nfs_direct_write_result(). Otherwise, if 881 * no requests have been sent, just return an error. 882 */ 883 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq, 884 struct iov_iter *iter, 885 loff_t pos) 886 { 887 struct nfs_pageio_descriptor desc; 888 struct inode *inode = dreq->inode; 889 ssize_t result = 0; 890 size_t requested_bytes = 0; 891 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE); 892 893 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false, 894 &nfs_direct_write_completion_ops); 895 desc.pg_dreq = dreq; 896 get_dreq(dreq); 897 inode_dio_begin(inode); 898 899 NFS_I(inode)->write_io += iov_iter_count(iter); 900 while (iov_iter_count(iter)) { 901 struct page **pagevec; 902 size_t bytes; 903 size_t pgbase; 904 unsigned npages, i; 905 906 result = iov_iter_get_pages_alloc(iter, &pagevec, 907 wsize, &pgbase); 908 if (result < 0) 909 break; 910 911 bytes = result; 912 iov_iter_advance(iter, bytes); 913 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 914 for (i = 0; i < npages; i++) { 915 struct nfs_page *req; 916 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 917 918 req = nfs_create_request(dreq->ctx, pagevec[i], NULL, 919 pgbase, req_len); 920 if (IS_ERR(req)) { 921 result = PTR_ERR(req); 922 break; 923 } 924 925 nfs_direct_setup_mirroring(dreq, &desc, req); 926 if (desc.pg_error < 0) { 927 nfs_free_request(req); 928 result = desc.pg_error; 929 break; 930 } 931 932 nfs_lock_request(req); 933 req->wb_index = pos >> PAGE_SHIFT; 934 req->wb_offset = pos & ~PAGE_MASK; 935 if (!nfs_pageio_add_request(&desc, req)) { 936 result = desc.pg_error; 937 nfs_unlock_and_release_request(req); 938 break; 939 } 940 pgbase = 0; 941 bytes -= req_len; 942 requested_bytes += req_len; 943 pos += req_len; 944 dreq->bytes_left -= req_len; 945 } 946 nfs_direct_release_pages(pagevec, npages); 947 kvfree(pagevec); 948 if (result < 0) 949 break; 950 } 951 nfs_pageio_complete(&desc); 952 953 /* 954 * If no bytes were started, return the error, and let the 955 * generic layer handle the completion. 956 */ 957 if (requested_bytes == 0) { 958 inode_dio_end(inode); 959 nfs_direct_req_release(dreq); 960 return result < 0 ? result : -EIO; 961 } 962 963 if (put_dreq(dreq)) 964 nfs_direct_write_complete(dreq, dreq->inode); 965 return 0; 966 } 967 968 /** 969 * nfs_file_direct_write - file direct write operation for NFS files 970 * @iocb: target I/O control block 971 * @iter: vector of user buffers from which to write data 972 * @pos: byte offset in file where writing starts 973 * 974 * We use this function for direct writes instead of calling 975 * generic_file_aio_write() in order to avoid taking the inode 976 * semaphore and updating the i_size. The NFS server will set 977 * the new i_size and this client must read the updated size 978 * back into its cache. We let the server do generic write 979 * parameter checking and report problems. 980 * 981 * We eliminate local atime updates, see direct read above. 982 * 983 * We avoid unnecessary page cache invalidations for normal cached 984 * readers of this file. 985 * 986 * Note that O_APPEND is not supported for NFS direct writes, as there 987 * is no atomic O_APPEND write facility in the NFS protocol. 988 */ 989 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter) 990 { 991 ssize_t result = -EINVAL; 992 struct file *file = iocb->ki_filp; 993 struct address_space *mapping = file->f_mapping; 994 struct inode *inode = mapping->host; 995 struct nfs_direct_req *dreq; 996 struct nfs_lock_context *l_ctx; 997 loff_t pos, end; 998 999 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", 1000 file, iov_iter_count(iter), (long long) iocb->ki_pos); 1001 1002 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, 1003 iov_iter_count(iter)); 1004 1005 pos = iocb->ki_pos; 1006 end = (pos + iov_iter_count(iter) - 1) >> PAGE_CACHE_SHIFT; 1007 1008 inode_lock(inode); 1009 1010 result = nfs_sync_mapping(mapping); 1011 if (result) 1012 goto out_unlock; 1013 1014 if (mapping->nrpages) { 1015 result = invalidate_inode_pages2_range(mapping, 1016 pos >> PAGE_CACHE_SHIFT, end); 1017 if (result) 1018 goto out_unlock; 1019 } 1020 1021 task_io_account_write(iov_iter_count(iter)); 1022 1023 result = -ENOMEM; 1024 dreq = nfs_direct_req_alloc(); 1025 if (!dreq) 1026 goto out_unlock; 1027 1028 dreq->inode = inode; 1029 dreq->bytes_left = iov_iter_count(iter); 1030 dreq->io_start = pos; 1031 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 1032 l_ctx = nfs_get_lock_context(dreq->ctx); 1033 if (IS_ERR(l_ctx)) { 1034 result = PTR_ERR(l_ctx); 1035 goto out_release; 1036 } 1037 dreq->l_ctx = l_ctx; 1038 if (!is_sync_kiocb(iocb)) 1039 dreq->iocb = iocb; 1040 1041 result = nfs_direct_write_schedule_iovec(dreq, iter, pos); 1042 1043 if (mapping->nrpages) { 1044 invalidate_inode_pages2_range(mapping, 1045 pos >> PAGE_CACHE_SHIFT, end); 1046 } 1047 1048 inode_unlock(inode); 1049 1050 if (!result) { 1051 result = nfs_direct_wait(dreq); 1052 if (result > 0) { 1053 struct inode *inode = mapping->host; 1054 1055 iocb->ki_pos = pos + result; 1056 spin_lock(&inode->i_lock); 1057 if (i_size_read(inode) < iocb->ki_pos) 1058 i_size_write(inode, iocb->ki_pos); 1059 spin_unlock(&inode->i_lock); 1060 generic_write_sync(file, pos, result); 1061 } 1062 } 1063 nfs_direct_req_release(dreq); 1064 return result; 1065 1066 out_release: 1067 nfs_direct_req_release(dreq); 1068 out_unlock: 1069 inode_unlock(inode); 1070 return result; 1071 } 1072 1073 /** 1074 * nfs_init_directcache - create a slab cache for nfs_direct_req structures 1075 * 1076 */ 1077 int __init nfs_init_directcache(void) 1078 { 1079 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache", 1080 sizeof(struct nfs_direct_req), 1081 0, (SLAB_RECLAIM_ACCOUNT| 1082 SLAB_MEM_SPREAD), 1083 NULL); 1084 if (nfs_direct_cachep == NULL) 1085 return -ENOMEM; 1086 1087 return 0; 1088 } 1089 1090 /** 1091 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures 1092 * 1093 */ 1094 void nfs_destroy_directcache(void) 1095 { 1096 kmem_cache_destroy(nfs_direct_cachep); 1097 } 1098