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 <linux/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 max_count, /* max expected count */ 91 bytes_left, /* bytes left to be sent */ 92 io_start, /* start of IO */ 93 error; /* any reported error */ 94 struct completion completion; /* wait for i/o completion */ 95 96 /* commit state */ 97 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */ 98 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */ 99 struct work_struct work; 100 int flags; 101 #define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */ 102 #define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */ 103 struct nfs_writeverf verf; /* unstable write verifier */ 104 }; 105 106 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops; 107 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops; 108 static void nfs_direct_write_complete(struct nfs_direct_req *dreq); 109 static void nfs_direct_write_schedule_work(struct work_struct *work); 110 111 static inline void get_dreq(struct nfs_direct_req *dreq) 112 { 113 atomic_inc(&dreq->io_count); 114 } 115 116 static inline int put_dreq(struct nfs_direct_req *dreq) 117 { 118 return atomic_dec_and_test(&dreq->io_count); 119 } 120 121 static void 122 nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr) 123 { 124 int i; 125 ssize_t count; 126 127 WARN_ON_ONCE(dreq->count >= dreq->max_count); 128 129 if (dreq->mirror_count == 1) { 130 dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes; 131 dreq->count += hdr->good_bytes; 132 } else { 133 /* mirrored writes */ 134 count = dreq->mirrors[hdr->pgio_mirror_idx].count; 135 if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) { 136 count = hdr->io_start + hdr->good_bytes - dreq->io_start; 137 dreq->mirrors[hdr->pgio_mirror_idx].count = count; 138 } 139 /* update the dreq->count by finding the minimum agreed count from all 140 * mirrors */ 141 count = dreq->mirrors[0].count; 142 143 for (i = 1; i < dreq->mirror_count; i++) 144 count = min(count, dreq->mirrors[i].count); 145 146 dreq->count = count; 147 } 148 } 149 150 /* 151 * nfs_direct_select_verf - select the right verifier 152 * @dreq - direct request possibly spanning multiple servers 153 * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs 154 * @commit_idx - commit bucket index for the DS 155 * 156 * returns the correct verifier to use given the role of the server 157 */ 158 static struct nfs_writeverf * 159 nfs_direct_select_verf(struct nfs_direct_req *dreq, 160 struct nfs_client *ds_clp, 161 int commit_idx) 162 { 163 struct nfs_writeverf *verfp = &dreq->verf; 164 165 #ifdef CONFIG_NFS_V4_1 166 /* 167 * pNFS is in use, use the DS verf except commit_through_mds is set 168 * for layout segment where nbuckets is zero. 169 */ 170 if (ds_clp && dreq->ds_cinfo.nbuckets > 0) { 171 if (commit_idx >= 0 && commit_idx < dreq->ds_cinfo.nbuckets) 172 verfp = &dreq->ds_cinfo.buckets[commit_idx].direct_verf; 173 else 174 WARN_ON_ONCE(1); 175 } 176 #endif 177 return verfp; 178 } 179 180 181 /* 182 * nfs_direct_set_hdr_verf - set the write/commit verifier 183 * @dreq - direct request possibly spanning multiple servers 184 * @hdr - pageio header to validate against previously seen verfs 185 * 186 * Set the server's (MDS or DS) "seen" verifier 187 */ 188 static void nfs_direct_set_hdr_verf(struct nfs_direct_req *dreq, 189 struct nfs_pgio_header *hdr) 190 { 191 struct nfs_writeverf *verfp; 192 193 verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx); 194 WARN_ON_ONCE(verfp->committed >= 0); 195 memcpy(verfp, &hdr->verf, sizeof(struct nfs_writeverf)); 196 WARN_ON_ONCE(verfp->committed < 0); 197 } 198 199 static int nfs_direct_cmp_verf(const struct nfs_writeverf *v1, 200 const struct nfs_writeverf *v2) 201 { 202 return nfs_write_verifier_cmp(&v1->verifier, &v2->verifier); 203 } 204 205 /* 206 * nfs_direct_cmp_hdr_verf - compare verifier for pgio header 207 * @dreq - direct request possibly spanning multiple servers 208 * @hdr - pageio header to validate against previously seen verf 209 * 210 * set the server's "seen" verf if not initialized. 211 * returns result of comparison between @hdr->verf and the "seen" 212 * verf of the server used by @hdr (DS or MDS) 213 */ 214 static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq, 215 struct nfs_pgio_header *hdr) 216 { 217 struct nfs_writeverf *verfp; 218 219 verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx); 220 if (verfp->committed < 0) { 221 nfs_direct_set_hdr_verf(dreq, hdr); 222 return 0; 223 } 224 return nfs_direct_cmp_verf(verfp, &hdr->verf); 225 } 226 227 /* 228 * nfs_direct_cmp_commit_data_verf - compare verifier for commit data 229 * @dreq - direct request possibly spanning multiple servers 230 * @data - commit data to validate against previously seen verf 231 * 232 * returns result of comparison between @data->verf and the verf of 233 * the server used by @data (DS or MDS) 234 */ 235 static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq, 236 struct nfs_commit_data *data) 237 { 238 struct nfs_writeverf *verfp; 239 240 verfp = nfs_direct_select_verf(dreq, data->ds_clp, 241 data->ds_commit_index); 242 243 /* verifier not set so always fail */ 244 if (verfp->committed < 0) 245 return 1; 246 247 return nfs_direct_cmp_verf(verfp, &data->verf); 248 } 249 250 /** 251 * nfs_direct_IO - NFS address space operation for direct I/O 252 * @iocb: target I/O control block 253 * @iter: I/O buffer 254 * 255 * The presence of this routine in the address space ops vector means 256 * the NFS client supports direct I/O. However, for most direct IO, we 257 * shunt off direct read and write requests before the VFS gets them, 258 * so this method is only ever called for swap. 259 */ 260 ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 261 { 262 struct inode *inode = iocb->ki_filp->f_mapping->host; 263 264 /* we only support swap file calling nfs_direct_IO */ 265 if (!IS_SWAPFILE(inode)) 266 return 0; 267 268 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE); 269 270 if (iov_iter_rw(iter) == READ) 271 return nfs_file_direct_read(iocb, iter); 272 return nfs_file_direct_write(iocb, iter); 273 } 274 275 static void nfs_direct_release_pages(struct page **pages, unsigned int npages) 276 { 277 unsigned int i; 278 for (i = 0; i < npages; i++) 279 put_page(pages[i]); 280 } 281 282 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo, 283 struct nfs_direct_req *dreq) 284 { 285 cinfo->inode = dreq->inode; 286 cinfo->mds = &dreq->mds_cinfo; 287 cinfo->ds = &dreq->ds_cinfo; 288 cinfo->dreq = dreq; 289 cinfo->completion_ops = &nfs_direct_commit_completion_ops; 290 } 291 292 static inline void nfs_direct_setup_mirroring(struct nfs_direct_req *dreq, 293 struct nfs_pageio_descriptor *pgio, 294 struct nfs_page *req) 295 { 296 int mirror_count = 1; 297 298 if (pgio->pg_ops->pg_get_mirror_count) 299 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req); 300 301 dreq->mirror_count = mirror_count; 302 } 303 304 static inline struct nfs_direct_req *nfs_direct_req_alloc(void) 305 { 306 struct nfs_direct_req *dreq; 307 308 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL); 309 if (!dreq) 310 return NULL; 311 312 kref_init(&dreq->kref); 313 kref_get(&dreq->kref); 314 init_completion(&dreq->completion); 315 INIT_LIST_HEAD(&dreq->mds_cinfo.list); 316 dreq->verf.committed = NFS_INVALID_STABLE_HOW; /* not set yet */ 317 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work); 318 dreq->mirror_count = 1; 319 spin_lock_init(&dreq->lock); 320 321 return dreq; 322 } 323 324 static void nfs_direct_req_free(struct kref *kref) 325 { 326 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref); 327 328 nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo); 329 if (dreq->l_ctx != NULL) 330 nfs_put_lock_context(dreq->l_ctx); 331 if (dreq->ctx != NULL) 332 put_nfs_open_context(dreq->ctx); 333 kmem_cache_free(nfs_direct_cachep, dreq); 334 } 335 336 static void nfs_direct_req_release(struct nfs_direct_req *dreq) 337 { 338 kref_put(&dreq->kref, nfs_direct_req_free); 339 } 340 341 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq) 342 { 343 return dreq->bytes_left; 344 } 345 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left); 346 347 /* 348 * Collects and returns the final error value/byte-count. 349 */ 350 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq) 351 { 352 ssize_t result = -EIOCBQUEUED; 353 354 /* Async requests don't wait here */ 355 if (dreq->iocb) 356 goto out; 357 358 result = wait_for_completion_killable(&dreq->completion); 359 360 if (!result) { 361 result = dreq->count; 362 WARN_ON_ONCE(dreq->count < 0); 363 } 364 if (!result) 365 result = dreq->error; 366 367 out: 368 return (ssize_t) result; 369 } 370 371 /* 372 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust 373 * the iocb is still valid here if this is a synchronous request. 374 */ 375 static void nfs_direct_complete(struct nfs_direct_req *dreq) 376 { 377 struct inode *inode = dreq->inode; 378 379 inode_dio_end(inode); 380 381 if (dreq->iocb) { 382 long res = (long) dreq->error; 383 if (dreq->count != 0) { 384 res = (long) dreq->count; 385 WARN_ON_ONCE(dreq->count < 0); 386 } 387 dreq->iocb->ki_complete(dreq->iocb, res, 0); 388 } 389 390 complete(&dreq->completion); 391 392 nfs_direct_req_release(dreq); 393 } 394 395 static void nfs_direct_readpage_release(struct nfs_page *req) 396 { 397 dprintk("NFS: direct read done (%s/%llu %d@%lld)\n", 398 req->wb_context->dentry->d_sb->s_id, 399 (unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)), 400 req->wb_bytes, 401 (long long)req_offset(req)); 402 nfs_release_request(req); 403 } 404 405 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) 406 { 407 unsigned long bytes = 0; 408 struct nfs_direct_req *dreq = hdr->dreq; 409 410 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 411 goto out_put; 412 413 spin_lock(&dreq->lock); 414 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0)) 415 dreq->error = hdr->error; 416 else 417 nfs_direct_good_bytes(dreq, hdr); 418 419 spin_unlock(&dreq->lock); 420 421 while (!list_empty(&hdr->pages)) { 422 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 423 struct page *page = req->wb_page; 424 425 if (!PageCompound(page) && bytes < hdr->good_bytes) 426 set_page_dirty(page); 427 bytes += req->wb_bytes; 428 nfs_list_remove_request(req); 429 nfs_direct_readpage_release(req); 430 } 431 out_put: 432 if (put_dreq(dreq)) 433 nfs_direct_complete(dreq); 434 hdr->release(hdr); 435 } 436 437 static void nfs_read_sync_pgio_error(struct list_head *head) 438 { 439 struct nfs_page *req; 440 441 while (!list_empty(head)) { 442 req = nfs_list_entry(head->next); 443 nfs_list_remove_request(req); 444 nfs_release_request(req); 445 } 446 } 447 448 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr) 449 { 450 get_dreq(hdr->dreq); 451 } 452 453 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = { 454 .error_cleanup = nfs_read_sync_pgio_error, 455 .init_hdr = nfs_direct_pgio_init, 456 .completion = nfs_direct_read_completion, 457 }; 458 459 /* 460 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ 461 * operation. If nfs_readdata_alloc() or get_user_pages() fails, 462 * bail and stop sending more reads. Read length accounting is 463 * handled automatically by nfs_direct_read_result(). Otherwise, if 464 * no requests have been sent, just return an error. 465 */ 466 467 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq, 468 struct iov_iter *iter, 469 loff_t pos) 470 { 471 struct nfs_pageio_descriptor desc; 472 struct inode *inode = dreq->inode; 473 ssize_t result = -EINVAL; 474 size_t requested_bytes = 0; 475 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE); 476 477 nfs_pageio_init_read(&desc, dreq->inode, false, 478 &nfs_direct_read_completion_ops); 479 get_dreq(dreq); 480 desc.pg_dreq = dreq; 481 inode_dio_begin(inode); 482 483 while (iov_iter_count(iter)) { 484 struct page **pagevec; 485 size_t bytes; 486 size_t pgbase; 487 unsigned npages, i; 488 489 result = iov_iter_get_pages_alloc(iter, &pagevec, 490 rsize, &pgbase); 491 if (result < 0) 492 break; 493 494 bytes = result; 495 iov_iter_advance(iter, bytes); 496 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 497 for (i = 0; i < npages; i++) { 498 struct nfs_page *req; 499 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 500 /* XXX do we need to do the eof zeroing found in async_filler? */ 501 req = nfs_create_request(dreq->ctx, pagevec[i], NULL, 502 pgbase, req_len); 503 if (IS_ERR(req)) { 504 result = PTR_ERR(req); 505 break; 506 } 507 req->wb_index = pos >> PAGE_SHIFT; 508 req->wb_offset = pos & ~PAGE_MASK; 509 if (!nfs_pageio_add_request(&desc, req)) { 510 result = desc.pg_error; 511 nfs_release_request(req); 512 break; 513 } 514 pgbase = 0; 515 bytes -= req_len; 516 requested_bytes += req_len; 517 pos += req_len; 518 dreq->bytes_left -= req_len; 519 } 520 nfs_direct_release_pages(pagevec, npages); 521 kvfree(pagevec); 522 if (result < 0) 523 break; 524 } 525 526 nfs_pageio_complete(&desc); 527 528 /* 529 * If no bytes were started, return the error, and let the 530 * generic layer handle the completion. 531 */ 532 if (requested_bytes == 0) { 533 inode_dio_end(inode); 534 nfs_direct_req_release(dreq); 535 return result < 0 ? result : -EIO; 536 } 537 538 if (put_dreq(dreq)) 539 nfs_direct_complete(dreq); 540 return requested_bytes; 541 } 542 543 /** 544 * nfs_file_direct_read - file direct read operation for NFS files 545 * @iocb: target I/O control block 546 * @iter: vector of user buffers into which to read data 547 * 548 * We use this function for direct reads instead of calling 549 * generic_file_aio_read() in order to avoid gfar's check to see if 550 * the request starts before the end of the file. For that check 551 * to work, we must generate a GETATTR before each direct read, and 552 * even then there is a window between the GETATTR and the subsequent 553 * READ where the file size could change. Our preference is simply 554 * to do all reads the application wants, and the server will take 555 * care of managing the end of file boundary. 556 * 557 * This function also eliminates unnecessarily updating the file's 558 * atime locally, as the NFS server sets the file's atime, and this 559 * client must read the updated atime from the server back into its 560 * cache. 561 */ 562 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter) 563 { 564 struct file *file = iocb->ki_filp; 565 struct address_space *mapping = file->f_mapping; 566 struct inode *inode = mapping->host; 567 struct nfs_direct_req *dreq; 568 struct nfs_lock_context *l_ctx; 569 ssize_t result = -EINVAL, requested; 570 size_t count = iov_iter_count(iter); 571 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count); 572 573 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n", 574 file, count, (long long) iocb->ki_pos); 575 576 result = 0; 577 if (!count) 578 goto out; 579 580 task_io_account_read(count); 581 582 result = -ENOMEM; 583 dreq = nfs_direct_req_alloc(); 584 if (dreq == NULL) 585 goto out; 586 587 dreq->inode = inode; 588 dreq->bytes_left = dreq->max_count = count; 589 dreq->io_start = iocb->ki_pos; 590 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 591 l_ctx = nfs_get_lock_context(dreq->ctx); 592 if (IS_ERR(l_ctx)) { 593 result = PTR_ERR(l_ctx); 594 goto out_release; 595 } 596 dreq->l_ctx = l_ctx; 597 if (!is_sync_kiocb(iocb)) 598 dreq->iocb = iocb; 599 600 nfs_start_io_direct(inode); 601 602 NFS_I(inode)->read_io += count; 603 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos); 604 605 nfs_end_io_direct(inode); 606 607 if (requested > 0) { 608 result = nfs_direct_wait(dreq); 609 if (result > 0) { 610 requested -= result; 611 iocb->ki_pos += result; 612 } 613 iov_iter_revert(iter, requested); 614 } else { 615 result = requested; 616 } 617 618 out_release: 619 nfs_direct_req_release(dreq); 620 out: 621 return result; 622 } 623 624 static void 625 nfs_direct_write_scan_commit_list(struct inode *inode, 626 struct list_head *list, 627 struct nfs_commit_info *cinfo) 628 { 629 spin_lock(&cinfo->inode->i_lock); 630 #ifdef CONFIG_NFS_V4_1 631 if (cinfo->ds != NULL && cinfo->ds->nwritten != 0) 632 NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo); 633 #endif 634 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0); 635 spin_unlock(&cinfo->inode->i_lock); 636 } 637 638 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) 639 { 640 struct nfs_pageio_descriptor desc; 641 struct nfs_page *req, *tmp; 642 LIST_HEAD(reqs); 643 struct nfs_commit_info cinfo; 644 LIST_HEAD(failed); 645 int i; 646 647 nfs_init_cinfo_from_dreq(&cinfo, dreq); 648 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 649 650 dreq->count = 0; 651 dreq->verf.committed = NFS_INVALID_STABLE_HOW; 652 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo); 653 for (i = 0; i < dreq->mirror_count; i++) 654 dreq->mirrors[i].count = 0; 655 get_dreq(dreq); 656 657 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false, 658 &nfs_direct_write_completion_ops); 659 desc.pg_dreq = dreq; 660 661 req = nfs_list_entry(reqs.next); 662 nfs_direct_setup_mirroring(dreq, &desc, req); 663 if (desc.pg_error < 0) { 664 list_splice_init(&reqs, &failed); 665 goto out_failed; 666 } 667 668 list_for_each_entry_safe(req, tmp, &reqs, wb_list) { 669 if (!nfs_pageio_add_request(&desc, req)) { 670 nfs_list_remove_request(req); 671 nfs_list_add_request(req, &failed); 672 spin_lock(&cinfo.inode->i_lock); 673 dreq->flags = 0; 674 if (desc.pg_error < 0) 675 dreq->error = desc.pg_error; 676 else 677 dreq->error = -EIO; 678 spin_unlock(&cinfo.inode->i_lock); 679 } 680 nfs_release_request(req); 681 } 682 nfs_pageio_complete(&desc); 683 684 out_failed: 685 while (!list_empty(&failed)) { 686 req = nfs_list_entry(failed.next); 687 nfs_list_remove_request(req); 688 nfs_unlock_and_release_request(req); 689 } 690 691 if (put_dreq(dreq)) 692 nfs_direct_write_complete(dreq); 693 } 694 695 static void nfs_direct_commit_complete(struct nfs_commit_data *data) 696 { 697 struct nfs_direct_req *dreq = data->dreq; 698 struct nfs_commit_info cinfo; 699 struct nfs_page *req; 700 int status = data->task.tk_status; 701 702 nfs_init_cinfo_from_dreq(&cinfo, dreq); 703 if (status < 0) { 704 dprintk("NFS: %5u commit failed with error %d.\n", 705 data->task.tk_pid, status); 706 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 707 } else if (nfs_direct_cmp_commit_data_verf(dreq, data)) { 708 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid); 709 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 710 } 711 712 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status); 713 while (!list_empty(&data->pages)) { 714 req = nfs_list_entry(data->pages.next); 715 nfs_list_remove_request(req); 716 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) { 717 /* Note the rewrite will go through mds */ 718 nfs_mark_request_commit(req, NULL, &cinfo, 0); 719 } else 720 nfs_release_request(req); 721 nfs_unlock_and_release_request(req); 722 } 723 724 if (atomic_dec_and_test(&cinfo.mds->rpcs_out)) 725 nfs_direct_write_complete(dreq); 726 } 727 728 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo, 729 struct nfs_page *req) 730 { 731 struct nfs_direct_req *dreq = cinfo->dreq; 732 733 spin_lock(&dreq->lock); 734 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 735 spin_unlock(&dreq->lock); 736 nfs_mark_request_commit(req, NULL, cinfo, 0); 737 } 738 739 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = { 740 .completion = nfs_direct_commit_complete, 741 .resched_write = nfs_direct_resched_write, 742 }; 743 744 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) 745 { 746 int res; 747 struct nfs_commit_info cinfo; 748 LIST_HEAD(mds_list); 749 750 nfs_init_cinfo_from_dreq(&cinfo, dreq); 751 nfs_scan_commit(dreq->inode, &mds_list, &cinfo); 752 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo); 753 if (res < 0) /* res == -ENOMEM */ 754 nfs_direct_write_reschedule(dreq); 755 } 756 757 static void nfs_direct_write_schedule_work(struct work_struct *work) 758 { 759 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work); 760 int flags = dreq->flags; 761 762 dreq->flags = 0; 763 switch (flags) { 764 case NFS_ODIRECT_DO_COMMIT: 765 nfs_direct_commit_schedule(dreq); 766 break; 767 case NFS_ODIRECT_RESCHED_WRITES: 768 nfs_direct_write_reschedule(dreq); 769 break; 770 default: 771 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping); 772 nfs_direct_complete(dreq); 773 } 774 } 775 776 static void nfs_direct_write_complete(struct nfs_direct_req *dreq) 777 { 778 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */ 779 } 780 781 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) 782 { 783 struct nfs_direct_req *dreq = hdr->dreq; 784 struct nfs_commit_info cinfo; 785 bool request_commit = false; 786 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 787 788 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 789 goto out_put; 790 791 nfs_init_cinfo_from_dreq(&cinfo, dreq); 792 793 spin_lock(&dreq->lock); 794 795 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 796 dreq->flags = 0; 797 dreq->error = hdr->error; 798 } 799 if (dreq->error == 0) { 800 nfs_direct_good_bytes(dreq, hdr); 801 if (nfs_write_need_commit(hdr)) { 802 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) 803 request_commit = true; 804 else if (dreq->flags == 0) { 805 nfs_direct_set_hdr_verf(dreq, hdr); 806 request_commit = true; 807 dreq->flags = NFS_ODIRECT_DO_COMMIT; 808 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) { 809 request_commit = true; 810 if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr)) 811 dreq->flags = 812 NFS_ODIRECT_RESCHED_WRITES; 813 } 814 } 815 } 816 spin_unlock(&dreq->lock); 817 818 while (!list_empty(&hdr->pages)) { 819 820 req = nfs_list_entry(hdr->pages.next); 821 nfs_list_remove_request(req); 822 if (request_commit) { 823 kref_get(&req->wb_kref); 824 nfs_mark_request_commit(req, hdr->lseg, &cinfo, 825 hdr->ds_commit_idx); 826 } 827 nfs_unlock_and_release_request(req); 828 } 829 830 out_put: 831 if (put_dreq(dreq)) 832 nfs_direct_write_complete(dreq); 833 hdr->release(hdr); 834 } 835 836 static void nfs_write_sync_pgio_error(struct list_head *head) 837 { 838 struct nfs_page *req; 839 840 while (!list_empty(head)) { 841 req = nfs_list_entry(head->next); 842 nfs_list_remove_request(req); 843 nfs_unlock_and_release_request(req); 844 } 845 } 846 847 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr) 848 { 849 struct nfs_direct_req *dreq = hdr->dreq; 850 851 spin_lock(&dreq->lock); 852 if (dreq->error == 0) { 853 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 854 /* fake unstable write to let common nfs resend pages */ 855 hdr->verf.committed = NFS_UNSTABLE; 856 hdr->good_bytes = hdr->args.count; 857 } 858 spin_unlock(&dreq->lock); 859 } 860 861 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = { 862 .error_cleanup = nfs_write_sync_pgio_error, 863 .init_hdr = nfs_direct_pgio_init, 864 .completion = nfs_direct_write_completion, 865 .reschedule_io = nfs_direct_write_reschedule_io, 866 }; 867 868 869 /* 870 * NB: Return the value of the first error return code. Subsequent 871 * errors after the first one are ignored. 872 */ 873 /* 874 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE 875 * operation. If nfs_writedata_alloc() or get_user_pages() fails, 876 * bail and stop sending more writes. Write length accounting is 877 * handled automatically by nfs_direct_write_result(). Otherwise, if 878 * no requests have been sent, just return an error. 879 */ 880 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq, 881 struct iov_iter *iter, 882 loff_t pos) 883 { 884 struct nfs_pageio_descriptor desc; 885 struct inode *inode = dreq->inode; 886 ssize_t result = 0; 887 size_t requested_bytes = 0; 888 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE); 889 890 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false, 891 &nfs_direct_write_completion_ops); 892 desc.pg_dreq = dreq; 893 get_dreq(dreq); 894 inode_dio_begin(inode); 895 896 NFS_I(inode)->write_io += iov_iter_count(iter); 897 while (iov_iter_count(iter)) { 898 struct page **pagevec; 899 size_t bytes; 900 size_t pgbase; 901 unsigned npages, i; 902 903 result = iov_iter_get_pages_alloc(iter, &pagevec, 904 wsize, &pgbase); 905 if (result < 0) 906 break; 907 908 bytes = result; 909 iov_iter_advance(iter, bytes); 910 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 911 for (i = 0; i < npages; i++) { 912 struct nfs_page *req; 913 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 914 915 req = nfs_create_request(dreq->ctx, pagevec[i], NULL, 916 pgbase, req_len); 917 if (IS_ERR(req)) { 918 result = PTR_ERR(req); 919 break; 920 } 921 922 nfs_direct_setup_mirroring(dreq, &desc, req); 923 if (desc.pg_error < 0) { 924 nfs_free_request(req); 925 result = desc.pg_error; 926 break; 927 } 928 929 nfs_lock_request(req); 930 req->wb_index = pos >> PAGE_SHIFT; 931 req->wb_offset = pos & ~PAGE_MASK; 932 if (!nfs_pageio_add_request(&desc, req)) { 933 result = desc.pg_error; 934 nfs_unlock_and_release_request(req); 935 break; 936 } 937 pgbase = 0; 938 bytes -= req_len; 939 requested_bytes += req_len; 940 pos += req_len; 941 dreq->bytes_left -= req_len; 942 } 943 nfs_direct_release_pages(pagevec, npages); 944 kvfree(pagevec); 945 if (result < 0) 946 break; 947 } 948 nfs_pageio_complete(&desc); 949 950 /* 951 * If no bytes were started, return the error, and let the 952 * generic layer handle the completion. 953 */ 954 if (requested_bytes == 0) { 955 inode_dio_end(inode); 956 nfs_direct_req_release(dreq); 957 return result < 0 ? result : -EIO; 958 } 959 960 if (put_dreq(dreq)) 961 nfs_direct_write_complete(dreq); 962 return requested_bytes; 963 } 964 965 /** 966 * nfs_file_direct_write - file direct write operation for NFS files 967 * @iocb: target I/O control block 968 * @iter: vector of user buffers from which to write data 969 * 970 * We use this function for direct writes instead of calling 971 * generic_file_aio_write() in order to avoid taking the inode 972 * semaphore and updating the i_size. The NFS server will set 973 * the new i_size and this client must read the updated size 974 * back into its cache. We let the server do generic write 975 * parameter checking and report problems. 976 * 977 * We eliminate local atime updates, see direct read above. 978 * 979 * We avoid unnecessary page cache invalidations for normal cached 980 * readers of this file. 981 * 982 * Note that O_APPEND is not supported for NFS direct writes, as there 983 * is no atomic O_APPEND write facility in the NFS protocol. 984 */ 985 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter) 986 { 987 ssize_t result = -EINVAL, requested; 988 size_t count; 989 struct file *file = iocb->ki_filp; 990 struct address_space *mapping = file->f_mapping; 991 struct inode *inode = mapping->host; 992 struct nfs_direct_req *dreq; 993 struct nfs_lock_context *l_ctx; 994 loff_t pos, end; 995 996 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", 997 file, iov_iter_count(iter), (long long) iocb->ki_pos); 998 999 result = generic_write_checks(iocb, iter); 1000 if (result <= 0) 1001 return result; 1002 count = result; 1003 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count); 1004 1005 pos = iocb->ki_pos; 1006 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT; 1007 1008 task_io_account_write(count); 1009 1010 result = -ENOMEM; 1011 dreq = nfs_direct_req_alloc(); 1012 if (!dreq) 1013 goto out; 1014 1015 dreq->inode = inode; 1016 dreq->bytes_left = dreq->max_count = count; 1017 dreq->io_start = pos; 1018 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 1019 l_ctx = nfs_get_lock_context(dreq->ctx); 1020 if (IS_ERR(l_ctx)) { 1021 result = PTR_ERR(l_ctx); 1022 goto out_release; 1023 } 1024 dreq->l_ctx = l_ctx; 1025 if (!is_sync_kiocb(iocb)) 1026 dreq->iocb = iocb; 1027 1028 nfs_start_io_direct(inode); 1029 1030 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos); 1031 1032 if (mapping->nrpages) { 1033 invalidate_inode_pages2_range(mapping, 1034 pos >> PAGE_SHIFT, end); 1035 } 1036 1037 nfs_end_io_direct(inode); 1038 1039 if (requested > 0) { 1040 result = nfs_direct_wait(dreq); 1041 if (result > 0) { 1042 requested -= result; 1043 iocb->ki_pos = pos + result; 1044 /* XXX: should check the generic_write_sync retval */ 1045 generic_write_sync(iocb, result); 1046 } 1047 iov_iter_revert(iter, requested); 1048 } else { 1049 result = requested; 1050 } 1051 out_release: 1052 nfs_direct_req_release(dreq); 1053 out: 1054 return result; 1055 } 1056 1057 /** 1058 * nfs_init_directcache - create a slab cache for nfs_direct_req structures 1059 * 1060 */ 1061 int __init nfs_init_directcache(void) 1062 { 1063 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache", 1064 sizeof(struct nfs_direct_req), 1065 0, (SLAB_RECLAIM_ACCOUNT| 1066 SLAB_MEM_SPREAD), 1067 NULL); 1068 if (nfs_direct_cachep == NULL) 1069 return -ENOMEM; 1070 1071 return 0; 1072 } 1073 1074 /** 1075 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures 1076 * 1077 */ 1078 void nfs_destroy_directcache(void) 1079 { 1080 kmem_cache_destroy(nfs_direct_cachep); 1081 } 1082