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 0; 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; 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 result = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos); 604 605 nfs_end_io_direct(inode); 606 607 if (!result) { 608 result = nfs_direct_wait(dreq); 609 if (result > 0) 610 iocb->ki_pos += result; 611 } 612 613 out_release: 614 nfs_direct_req_release(dreq); 615 out: 616 return result; 617 } 618 619 static void 620 nfs_direct_write_scan_commit_list(struct inode *inode, 621 struct list_head *list, 622 struct nfs_commit_info *cinfo) 623 { 624 spin_lock(&cinfo->inode->i_lock); 625 #ifdef CONFIG_NFS_V4_1 626 if (cinfo->ds != NULL && cinfo->ds->nwritten != 0) 627 NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo); 628 #endif 629 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0); 630 spin_unlock(&cinfo->inode->i_lock); 631 } 632 633 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) 634 { 635 struct nfs_pageio_descriptor desc; 636 struct nfs_page *req, *tmp; 637 LIST_HEAD(reqs); 638 struct nfs_commit_info cinfo; 639 LIST_HEAD(failed); 640 int i; 641 642 nfs_init_cinfo_from_dreq(&cinfo, dreq); 643 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 644 645 dreq->count = 0; 646 dreq->verf.committed = NFS_INVALID_STABLE_HOW; 647 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo); 648 for (i = 0; i < dreq->mirror_count; i++) 649 dreq->mirrors[i].count = 0; 650 get_dreq(dreq); 651 652 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false, 653 &nfs_direct_write_completion_ops); 654 desc.pg_dreq = dreq; 655 656 req = nfs_list_entry(reqs.next); 657 nfs_direct_setup_mirroring(dreq, &desc, req); 658 if (desc.pg_error < 0) { 659 list_splice_init(&reqs, &failed); 660 goto out_failed; 661 } 662 663 list_for_each_entry_safe(req, tmp, &reqs, wb_list) { 664 if (!nfs_pageio_add_request(&desc, req)) { 665 nfs_list_remove_request(req); 666 nfs_list_add_request(req, &failed); 667 spin_lock(&cinfo.inode->i_lock); 668 dreq->flags = 0; 669 if (desc.pg_error < 0) 670 dreq->error = desc.pg_error; 671 else 672 dreq->error = -EIO; 673 spin_unlock(&cinfo.inode->i_lock); 674 } 675 nfs_release_request(req); 676 } 677 nfs_pageio_complete(&desc); 678 679 out_failed: 680 while (!list_empty(&failed)) { 681 req = nfs_list_entry(failed.next); 682 nfs_list_remove_request(req); 683 nfs_unlock_and_release_request(req); 684 } 685 686 if (put_dreq(dreq)) 687 nfs_direct_write_complete(dreq); 688 } 689 690 static void nfs_direct_commit_complete(struct nfs_commit_data *data) 691 { 692 struct nfs_direct_req *dreq = data->dreq; 693 struct nfs_commit_info cinfo; 694 struct nfs_page *req; 695 int status = data->task.tk_status; 696 697 nfs_init_cinfo_from_dreq(&cinfo, dreq); 698 if (status < 0) { 699 dprintk("NFS: %5u commit failed with error %d.\n", 700 data->task.tk_pid, status); 701 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 702 } else if (nfs_direct_cmp_commit_data_verf(dreq, data)) { 703 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid); 704 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 705 } 706 707 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status); 708 while (!list_empty(&data->pages)) { 709 req = nfs_list_entry(data->pages.next); 710 nfs_list_remove_request(req); 711 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) { 712 /* Note the rewrite will go through mds */ 713 nfs_mark_request_commit(req, NULL, &cinfo, 0); 714 } else 715 nfs_release_request(req); 716 nfs_unlock_and_release_request(req); 717 } 718 719 if (atomic_dec_and_test(&cinfo.mds->rpcs_out)) 720 nfs_direct_write_complete(dreq); 721 } 722 723 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo, 724 struct nfs_page *req) 725 { 726 struct nfs_direct_req *dreq = cinfo->dreq; 727 728 spin_lock(&dreq->lock); 729 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 730 spin_unlock(&dreq->lock); 731 nfs_mark_request_commit(req, NULL, cinfo, 0); 732 } 733 734 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = { 735 .completion = nfs_direct_commit_complete, 736 .resched_write = nfs_direct_resched_write, 737 }; 738 739 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) 740 { 741 int res; 742 struct nfs_commit_info cinfo; 743 LIST_HEAD(mds_list); 744 745 nfs_init_cinfo_from_dreq(&cinfo, dreq); 746 nfs_scan_commit(dreq->inode, &mds_list, &cinfo); 747 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo); 748 if (res < 0) /* res == -ENOMEM */ 749 nfs_direct_write_reschedule(dreq); 750 } 751 752 static void nfs_direct_write_schedule_work(struct work_struct *work) 753 { 754 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work); 755 int flags = dreq->flags; 756 757 dreq->flags = 0; 758 switch (flags) { 759 case NFS_ODIRECT_DO_COMMIT: 760 nfs_direct_commit_schedule(dreq); 761 break; 762 case NFS_ODIRECT_RESCHED_WRITES: 763 nfs_direct_write_reschedule(dreq); 764 break; 765 default: 766 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping); 767 nfs_direct_complete(dreq); 768 } 769 } 770 771 static void nfs_direct_write_complete(struct nfs_direct_req *dreq) 772 { 773 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */ 774 } 775 776 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) 777 { 778 struct nfs_direct_req *dreq = hdr->dreq; 779 struct nfs_commit_info cinfo; 780 bool request_commit = false; 781 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 782 783 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 784 goto out_put; 785 786 nfs_init_cinfo_from_dreq(&cinfo, dreq); 787 788 spin_lock(&dreq->lock); 789 790 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 791 dreq->flags = 0; 792 dreq->error = hdr->error; 793 } 794 if (dreq->error == 0) { 795 nfs_direct_good_bytes(dreq, hdr); 796 if (nfs_write_need_commit(hdr)) { 797 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) 798 request_commit = true; 799 else if (dreq->flags == 0) { 800 nfs_direct_set_hdr_verf(dreq, hdr); 801 request_commit = true; 802 dreq->flags = NFS_ODIRECT_DO_COMMIT; 803 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) { 804 request_commit = true; 805 if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr)) 806 dreq->flags = 807 NFS_ODIRECT_RESCHED_WRITES; 808 } 809 } 810 } 811 spin_unlock(&dreq->lock); 812 813 while (!list_empty(&hdr->pages)) { 814 815 req = nfs_list_entry(hdr->pages.next); 816 nfs_list_remove_request(req); 817 if (request_commit) { 818 kref_get(&req->wb_kref); 819 nfs_mark_request_commit(req, hdr->lseg, &cinfo, 820 hdr->ds_commit_idx); 821 } 822 nfs_unlock_and_release_request(req); 823 } 824 825 out_put: 826 if (put_dreq(dreq)) 827 nfs_direct_write_complete(dreq); 828 hdr->release(hdr); 829 } 830 831 static void nfs_write_sync_pgio_error(struct list_head *head) 832 { 833 struct nfs_page *req; 834 835 while (!list_empty(head)) { 836 req = nfs_list_entry(head->next); 837 nfs_list_remove_request(req); 838 nfs_unlock_and_release_request(req); 839 } 840 } 841 842 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr) 843 { 844 struct nfs_direct_req *dreq = hdr->dreq; 845 846 spin_lock(&dreq->lock); 847 if (dreq->error == 0) { 848 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 849 /* fake unstable write to let common nfs resend pages */ 850 hdr->verf.committed = NFS_UNSTABLE; 851 hdr->good_bytes = hdr->args.count; 852 } 853 spin_unlock(&dreq->lock); 854 } 855 856 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = { 857 .error_cleanup = nfs_write_sync_pgio_error, 858 .init_hdr = nfs_direct_pgio_init, 859 .completion = nfs_direct_write_completion, 860 .reschedule_io = nfs_direct_write_reschedule_io, 861 }; 862 863 864 /* 865 * NB: Return the value of the first error return code. Subsequent 866 * errors after the first one are ignored. 867 */ 868 /* 869 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE 870 * operation. If nfs_writedata_alloc() or get_user_pages() fails, 871 * bail and stop sending more writes. Write length accounting is 872 * handled automatically by nfs_direct_write_result(). Otherwise, if 873 * no requests have been sent, just return an error. 874 */ 875 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq, 876 struct iov_iter *iter, 877 loff_t pos) 878 { 879 struct nfs_pageio_descriptor desc; 880 struct inode *inode = dreq->inode; 881 ssize_t result = 0; 882 size_t requested_bytes = 0; 883 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE); 884 885 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false, 886 &nfs_direct_write_completion_ops); 887 desc.pg_dreq = dreq; 888 get_dreq(dreq); 889 inode_dio_begin(inode); 890 891 NFS_I(inode)->write_io += iov_iter_count(iter); 892 while (iov_iter_count(iter)) { 893 struct page **pagevec; 894 size_t bytes; 895 size_t pgbase; 896 unsigned npages, i; 897 898 result = iov_iter_get_pages_alloc(iter, &pagevec, 899 wsize, &pgbase); 900 if (result < 0) 901 break; 902 903 bytes = result; 904 iov_iter_advance(iter, bytes); 905 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 906 for (i = 0; i < npages; i++) { 907 struct nfs_page *req; 908 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 909 910 req = nfs_create_request(dreq->ctx, pagevec[i], NULL, 911 pgbase, req_len); 912 if (IS_ERR(req)) { 913 result = PTR_ERR(req); 914 break; 915 } 916 917 nfs_direct_setup_mirroring(dreq, &desc, req); 918 if (desc.pg_error < 0) { 919 nfs_free_request(req); 920 result = desc.pg_error; 921 break; 922 } 923 924 nfs_lock_request(req); 925 req->wb_index = pos >> PAGE_SHIFT; 926 req->wb_offset = pos & ~PAGE_MASK; 927 if (!nfs_pageio_add_request(&desc, req)) { 928 result = desc.pg_error; 929 nfs_unlock_and_release_request(req); 930 break; 931 } 932 pgbase = 0; 933 bytes -= req_len; 934 requested_bytes += req_len; 935 pos += req_len; 936 dreq->bytes_left -= req_len; 937 } 938 nfs_direct_release_pages(pagevec, npages); 939 kvfree(pagevec); 940 if (result < 0) 941 break; 942 } 943 nfs_pageio_complete(&desc); 944 945 /* 946 * If no bytes were started, return the error, and let the 947 * generic layer handle the completion. 948 */ 949 if (requested_bytes == 0) { 950 inode_dio_end(inode); 951 nfs_direct_req_release(dreq); 952 return result < 0 ? result : -EIO; 953 } 954 955 if (put_dreq(dreq)) 956 nfs_direct_write_complete(dreq); 957 return 0; 958 } 959 960 /** 961 * nfs_file_direct_write - file direct write operation for NFS files 962 * @iocb: target I/O control block 963 * @iter: vector of user buffers from which to write data 964 * 965 * We use this function for direct writes instead of calling 966 * generic_file_aio_write() in order to avoid taking the inode 967 * semaphore and updating the i_size. The NFS server will set 968 * the new i_size and this client must read the updated size 969 * back into its cache. We let the server do generic write 970 * parameter checking and report problems. 971 * 972 * We eliminate local atime updates, see direct read above. 973 * 974 * We avoid unnecessary page cache invalidations for normal cached 975 * readers of this file. 976 * 977 * Note that O_APPEND is not supported for NFS direct writes, as there 978 * is no atomic O_APPEND write facility in the NFS protocol. 979 */ 980 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter) 981 { 982 ssize_t result = -EINVAL; 983 size_t count; 984 struct file *file = iocb->ki_filp; 985 struct address_space *mapping = file->f_mapping; 986 struct inode *inode = mapping->host; 987 struct nfs_direct_req *dreq; 988 struct nfs_lock_context *l_ctx; 989 loff_t pos, end; 990 991 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", 992 file, iov_iter_count(iter), (long long) iocb->ki_pos); 993 994 result = generic_write_checks(iocb, iter); 995 if (result <= 0) 996 return result; 997 count = result; 998 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count); 999 1000 pos = iocb->ki_pos; 1001 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT; 1002 1003 task_io_account_write(count); 1004 1005 result = -ENOMEM; 1006 dreq = nfs_direct_req_alloc(); 1007 if (!dreq) 1008 goto out; 1009 1010 dreq->inode = inode; 1011 dreq->bytes_left = dreq->max_count = count; 1012 dreq->io_start = pos; 1013 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 1014 l_ctx = nfs_get_lock_context(dreq->ctx); 1015 if (IS_ERR(l_ctx)) { 1016 result = PTR_ERR(l_ctx); 1017 goto out_release; 1018 } 1019 dreq->l_ctx = l_ctx; 1020 if (!is_sync_kiocb(iocb)) 1021 dreq->iocb = iocb; 1022 1023 nfs_start_io_direct(inode); 1024 1025 result = nfs_direct_write_schedule_iovec(dreq, iter, pos); 1026 1027 if (mapping->nrpages) { 1028 invalidate_inode_pages2_range(mapping, 1029 pos >> PAGE_SHIFT, end); 1030 } 1031 1032 nfs_end_io_direct(inode); 1033 1034 if (!result) { 1035 result = nfs_direct_wait(dreq); 1036 if (result > 0) { 1037 iocb->ki_pos = pos + result; 1038 /* XXX: should check the generic_write_sync retval */ 1039 generic_write_sync(iocb, result); 1040 } 1041 } 1042 out_release: 1043 nfs_direct_req_release(dreq); 1044 out: 1045 return result; 1046 } 1047 1048 /** 1049 * nfs_init_directcache - create a slab cache for nfs_direct_req structures 1050 * 1051 */ 1052 int __init nfs_init_directcache(void) 1053 { 1054 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache", 1055 sizeof(struct nfs_direct_req), 1056 0, (SLAB_RECLAIM_ACCOUNT| 1057 SLAB_MEM_SPREAD), 1058 NULL); 1059 if (nfs_direct_cachep == NULL) 1060 return -ENOMEM; 1061 1062 return 0; 1063 } 1064 1065 /** 1066 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures 1067 * 1068 */ 1069 void nfs_destroy_directcache(void) 1070 { 1071 kmem_cache_destroy(nfs_direct_cachep); 1072 } 1073