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 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, struct inode *inode); 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 /* 200 * nfs_direct_cmp_hdr_verf - compare verifier for pgio header 201 * @dreq - direct request possibly spanning multiple servers 202 * @hdr - pageio header to validate against previously seen verf 203 * 204 * set the server's "seen" verf if not initialized. 205 * returns result of comparison between @hdr->verf and the "seen" 206 * verf of the server used by @hdr (DS or MDS) 207 */ 208 static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq, 209 struct nfs_pgio_header *hdr) 210 { 211 struct nfs_writeverf *verfp; 212 213 verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx); 214 if (verfp->committed < 0) { 215 nfs_direct_set_hdr_verf(dreq, hdr); 216 return 0; 217 } 218 return memcmp(verfp, &hdr->verf, sizeof(struct nfs_writeverf)); 219 } 220 221 /* 222 * nfs_direct_cmp_commit_data_verf - compare verifier for commit data 223 * @dreq - direct request possibly spanning multiple servers 224 * @data - commit data to validate against previously seen verf 225 * 226 * returns result of comparison between @data->verf and the verf of 227 * the server used by @data (DS or MDS) 228 */ 229 static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq, 230 struct nfs_commit_data *data) 231 { 232 struct nfs_writeverf *verfp; 233 234 verfp = nfs_direct_select_verf(dreq, data->ds_clp, 235 data->ds_commit_index); 236 237 /* verifier not set so always fail */ 238 if (verfp->committed < 0) 239 return 1; 240 241 return memcmp(verfp, &data->verf, sizeof(struct nfs_writeverf)); 242 } 243 244 /** 245 * nfs_direct_IO - NFS address space operation for direct I/O 246 * @iocb: target I/O control block 247 * @iov: array of vectors that define I/O buffer 248 * @pos: offset in file to begin the operation 249 * @nr_segs: size of iovec array 250 * 251 * The presence of this routine in the address space ops vector means 252 * the NFS client supports direct I/O. However, for most direct IO, we 253 * shunt off direct read and write requests before the VFS gets them, 254 * so this method is only ever called for swap. 255 */ 256 ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 257 { 258 struct inode *inode = iocb->ki_filp->f_mapping->host; 259 260 /* we only support swap file calling nfs_direct_IO */ 261 if (!IS_SWAPFILE(inode)) 262 return 0; 263 264 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE); 265 266 if (iov_iter_rw(iter) == READ) 267 return nfs_file_direct_read(iocb, iter); 268 return nfs_file_direct_write(iocb, iter); 269 } 270 271 static void nfs_direct_release_pages(struct page **pages, unsigned int npages) 272 { 273 unsigned int i; 274 for (i = 0; i < npages; i++) 275 put_page(pages[i]); 276 } 277 278 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo, 279 struct nfs_direct_req *dreq) 280 { 281 cinfo->inode = dreq->inode; 282 cinfo->mds = &dreq->mds_cinfo; 283 cinfo->ds = &dreq->ds_cinfo; 284 cinfo->dreq = dreq; 285 cinfo->completion_ops = &nfs_direct_commit_completion_ops; 286 } 287 288 static inline void nfs_direct_setup_mirroring(struct nfs_direct_req *dreq, 289 struct nfs_pageio_descriptor *pgio, 290 struct nfs_page *req) 291 { 292 int mirror_count = 1; 293 294 if (pgio->pg_ops->pg_get_mirror_count) 295 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req); 296 297 dreq->mirror_count = mirror_count; 298 } 299 300 static inline struct nfs_direct_req *nfs_direct_req_alloc(void) 301 { 302 struct nfs_direct_req *dreq; 303 304 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL); 305 if (!dreq) 306 return NULL; 307 308 kref_init(&dreq->kref); 309 kref_get(&dreq->kref); 310 init_completion(&dreq->completion); 311 INIT_LIST_HEAD(&dreq->mds_cinfo.list); 312 dreq->verf.committed = NFS_INVALID_STABLE_HOW; /* not set yet */ 313 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work); 314 dreq->mirror_count = 1; 315 spin_lock_init(&dreq->lock); 316 317 return dreq; 318 } 319 320 static void nfs_direct_req_free(struct kref *kref) 321 { 322 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref); 323 324 nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo); 325 if (dreq->l_ctx != NULL) 326 nfs_put_lock_context(dreq->l_ctx); 327 if (dreq->ctx != NULL) 328 put_nfs_open_context(dreq->ctx); 329 kmem_cache_free(nfs_direct_cachep, dreq); 330 } 331 332 static void nfs_direct_req_release(struct nfs_direct_req *dreq) 333 { 334 kref_put(&dreq->kref, nfs_direct_req_free); 335 } 336 337 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq) 338 { 339 return dreq->bytes_left; 340 } 341 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left); 342 343 /* 344 * Collects and returns the final error value/byte-count. 345 */ 346 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq) 347 { 348 ssize_t result = -EIOCBQUEUED; 349 350 /* Async requests don't wait here */ 351 if (dreq->iocb) 352 goto out; 353 354 result = wait_for_completion_killable(&dreq->completion); 355 356 if (!result) { 357 result = dreq->count; 358 WARN_ON_ONCE(dreq->count < 0); 359 } 360 if (!result) 361 result = dreq->error; 362 363 out: 364 return (ssize_t) result; 365 } 366 367 /* 368 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust 369 * the iocb is still valid here if this is a synchronous request. 370 */ 371 static void nfs_direct_complete(struct nfs_direct_req *dreq, bool write) 372 { 373 struct inode *inode = dreq->inode; 374 375 if (dreq->iocb && write) { 376 loff_t pos = dreq->iocb->ki_pos + dreq->count; 377 378 spin_lock(&inode->i_lock); 379 if (i_size_read(inode) < pos) 380 i_size_write(inode, pos); 381 spin_unlock(&inode->i_lock); 382 } 383 384 if (write) 385 nfs_zap_mapping(inode, inode->i_mapping); 386 387 inode_dio_end(inode); 388 389 if (dreq->iocb) { 390 long res = (long) dreq->error; 391 if (dreq->count != 0) { 392 res = (long) dreq->count; 393 WARN_ON_ONCE(dreq->count < 0); 394 } 395 dreq->iocb->ki_complete(dreq->iocb, res, 0); 396 } 397 398 complete_all(&dreq->completion); 399 400 nfs_direct_req_release(dreq); 401 } 402 403 static void nfs_direct_readpage_release(struct nfs_page *req) 404 { 405 dprintk("NFS: direct read done (%s/%llu %d@%lld)\n", 406 req->wb_context->dentry->d_sb->s_id, 407 (unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)), 408 req->wb_bytes, 409 (long long)req_offset(req)); 410 nfs_release_request(req); 411 } 412 413 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) 414 { 415 unsigned long bytes = 0; 416 struct nfs_direct_req *dreq = hdr->dreq; 417 418 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 419 goto out_put; 420 421 spin_lock(&dreq->lock); 422 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0)) 423 dreq->error = hdr->error; 424 else 425 nfs_direct_good_bytes(dreq, hdr); 426 427 spin_unlock(&dreq->lock); 428 429 while (!list_empty(&hdr->pages)) { 430 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 431 struct page *page = req->wb_page; 432 433 if (!PageCompound(page) && bytes < hdr->good_bytes) 434 set_page_dirty(page); 435 bytes += req->wb_bytes; 436 nfs_list_remove_request(req); 437 nfs_direct_readpage_release(req); 438 } 439 out_put: 440 if (put_dreq(dreq)) 441 nfs_direct_complete(dreq, false); 442 hdr->release(hdr); 443 } 444 445 static void nfs_read_sync_pgio_error(struct list_head *head) 446 { 447 struct nfs_page *req; 448 449 while (!list_empty(head)) { 450 req = nfs_list_entry(head->next); 451 nfs_list_remove_request(req); 452 nfs_release_request(req); 453 } 454 } 455 456 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr) 457 { 458 get_dreq(hdr->dreq); 459 } 460 461 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = { 462 .error_cleanup = nfs_read_sync_pgio_error, 463 .init_hdr = nfs_direct_pgio_init, 464 .completion = nfs_direct_read_completion, 465 }; 466 467 /* 468 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ 469 * operation. If nfs_readdata_alloc() or get_user_pages() fails, 470 * bail and stop sending more reads. Read length accounting is 471 * handled automatically by nfs_direct_read_result(). Otherwise, if 472 * no requests have been sent, just return an error. 473 */ 474 475 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq, 476 struct iov_iter *iter, 477 loff_t pos) 478 { 479 struct nfs_pageio_descriptor desc; 480 struct inode *inode = dreq->inode; 481 ssize_t result = -EINVAL; 482 size_t requested_bytes = 0; 483 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE); 484 485 nfs_pageio_init_read(&desc, dreq->inode, false, 486 &nfs_direct_read_completion_ops); 487 get_dreq(dreq); 488 desc.pg_dreq = dreq; 489 inode_dio_begin(inode); 490 491 while (iov_iter_count(iter)) { 492 struct page **pagevec; 493 size_t bytes; 494 size_t pgbase; 495 unsigned npages, i; 496 497 result = iov_iter_get_pages_alloc(iter, &pagevec, 498 rsize, &pgbase); 499 if (result < 0) 500 break; 501 502 bytes = result; 503 iov_iter_advance(iter, bytes); 504 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 505 for (i = 0; i < npages; i++) { 506 struct nfs_page *req; 507 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 508 /* XXX do we need to do the eof zeroing found in async_filler? */ 509 req = nfs_create_request(dreq->ctx, pagevec[i], NULL, 510 pgbase, req_len); 511 if (IS_ERR(req)) { 512 result = PTR_ERR(req); 513 break; 514 } 515 req->wb_index = pos >> PAGE_SHIFT; 516 req->wb_offset = pos & ~PAGE_MASK; 517 if (!nfs_pageio_add_request(&desc, req)) { 518 result = desc.pg_error; 519 nfs_release_request(req); 520 break; 521 } 522 pgbase = 0; 523 bytes -= req_len; 524 requested_bytes += req_len; 525 pos += req_len; 526 dreq->bytes_left -= req_len; 527 } 528 nfs_direct_release_pages(pagevec, npages); 529 kvfree(pagevec); 530 if (result < 0) 531 break; 532 } 533 534 nfs_pageio_complete(&desc); 535 536 /* 537 * If no bytes were started, return the error, and let the 538 * generic layer handle the completion. 539 */ 540 if (requested_bytes == 0) { 541 inode_dio_end(inode); 542 nfs_direct_req_release(dreq); 543 return result < 0 ? result : -EIO; 544 } 545 546 if (put_dreq(dreq)) 547 nfs_direct_complete(dreq, false); 548 return 0; 549 } 550 551 /** 552 * nfs_file_direct_read - file direct read operation for NFS files 553 * @iocb: target I/O control block 554 * @iter: vector of user buffers into which to read data 555 * 556 * We use this function for direct reads instead of calling 557 * generic_file_aio_read() in order to avoid gfar's check to see if 558 * the request starts before the end of the file. For that check 559 * to work, we must generate a GETATTR before each direct read, and 560 * even then there is a window between the GETATTR and the subsequent 561 * READ where the file size could change. Our preference is simply 562 * to do all reads the application wants, and the server will take 563 * care of managing the end of file boundary. 564 * 565 * This function also eliminates unnecessarily updating the file's 566 * atime locally, as the NFS server sets the file's atime, and this 567 * client must read the updated atime from the server back into its 568 * cache. 569 */ 570 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter) 571 { 572 struct file *file = iocb->ki_filp; 573 struct address_space *mapping = file->f_mapping; 574 struct inode *inode = mapping->host; 575 struct nfs_direct_req *dreq; 576 struct nfs_lock_context *l_ctx; 577 ssize_t result = -EINVAL; 578 size_t count = iov_iter_count(iter); 579 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count); 580 581 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n", 582 file, count, (long long) iocb->ki_pos); 583 584 result = 0; 585 if (!count) 586 goto out; 587 588 inode_lock(inode); 589 result = nfs_sync_mapping(mapping); 590 if (result) 591 goto out_unlock; 592 593 task_io_account_read(count); 594 595 result = -ENOMEM; 596 dreq = nfs_direct_req_alloc(); 597 if (dreq == NULL) 598 goto out_unlock; 599 600 dreq->inode = inode; 601 dreq->bytes_left = dreq->max_count = count; 602 dreq->io_start = iocb->ki_pos; 603 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 604 l_ctx = nfs_get_lock_context(dreq->ctx); 605 if (IS_ERR(l_ctx)) { 606 result = PTR_ERR(l_ctx); 607 goto out_release; 608 } 609 dreq->l_ctx = l_ctx; 610 if (!is_sync_kiocb(iocb)) 611 dreq->iocb = iocb; 612 613 NFS_I(inode)->read_io += count; 614 result = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos); 615 616 inode_unlock(inode); 617 618 if (!result) { 619 result = nfs_direct_wait(dreq); 620 if (result > 0) 621 iocb->ki_pos += result; 622 } 623 624 nfs_direct_req_release(dreq); 625 return result; 626 627 out_release: 628 nfs_direct_req_release(dreq); 629 out_unlock: 630 inode_unlock(inode); 631 out: 632 return result; 633 } 634 635 static void 636 nfs_direct_write_scan_commit_list(struct inode *inode, 637 struct list_head *list, 638 struct nfs_commit_info *cinfo) 639 { 640 spin_lock(&cinfo->inode->i_lock); 641 #ifdef CONFIG_NFS_V4_1 642 if (cinfo->ds != NULL && cinfo->ds->nwritten != 0) 643 NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo); 644 #endif 645 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0); 646 spin_unlock(&cinfo->inode->i_lock); 647 } 648 649 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) 650 { 651 struct nfs_pageio_descriptor desc; 652 struct nfs_page *req, *tmp; 653 LIST_HEAD(reqs); 654 struct nfs_commit_info cinfo; 655 LIST_HEAD(failed); 656 int i; 657 658 nfs_init_cinfo_from_dreq(&cinfo, dreq); 659 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); 660 661 dreq->count = 0; 662 for (i = 0; i < dreq->mirror_count; i++) 663 dreq->mirrors[i].count = 0; 664 get_dreq(dreq); 665 666 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false, 667 &nfs_direct_write_completion_ops); 668 desc.pg_dreq = dreq; 669 670 req = nfs_list_entry(reqs.next); 671 nfs_direct_setup_mirroring(dreq, &desc, req); 672 if (desc.pg_error < 0) { 673 list_splice_init(&reqs, &failed); 674 goto out_failed; 675 } 676 677 list_for_each_entry_safe(req, tmp, &reqs, wb_list) { 678 if (!nfs_pageio_add_request(&desc, req)) { 679 nfs_list_remove_request(req); 680 nfs_list_add_request(req, &failed); 681 spin_lock(&cinfo.inode->i_lock); 682 dreq->flags = 0; 683 if (desc.pg_error < 0) 684 dreq->error = desc.pg_error; 685 else 686 dreq->error = -EIO; 687 spin_unlock(&cinfo.inode->i_lock); 688 } 689 nfs_release_request(req); 690 } 691 nfs_pageio_complete(&desc); 692 693 out_failed: 694 while (!list_empty(&failed)) { 695 req = nfs_list_entry(failed.next); 696 nfs_list_remove_request(req); 697 nfs_unlock_and_release_request(req); 698 } 699 700 if (put_dreq(dreq)) 701 nfs_direct_write_complete(dreq, dreq->inode); 702 } 703 704 static void nfs_direct_commit_complete(struct nfs_commit_data *data) 705 { 706 struct nfs_direct_req *dreq = data->dreq; 707 struct nfs_commit_info cinfo; 708 struct nfs_page *req; 709 int status = data->task.tk_status; 710 711 nfs_init_cinfo_from_dreq(&cinfo, dreq); 712 if (status < 0) { 713 dprintk("NFS: %5u commit failed with error %d.\n", 714 data->task.tk_pid, status); 715 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 716 } else if (nfs_direct_cmp_commit_data_verf(dreq, data)) { 717 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid); 718 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 719 } 720 721 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status); 722 while (!list_empty(&data->pages)) { 723 req = nfs_list_entry(data->pages.next); 724 nfs_list_remove_request(req); 725 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) { 726 /* Note the rewrite will go through mds */ 727 nfs_mark_request_commit(req, NULL, &cinfo, 0); 728 } else 729 nfs_release_request(req); 730 nfs_unlock_and_release_request(req); 731 } 732 733 if (atomic_dec_and_test(&cinfo.mds->rpcs_out)) 734 nfs_direct_write_complete(dreq, data->inode); 735 } 736 737 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo, 738 struct nfs_page *req) 739 { 740 struct nfs_direct_req *dreq = cinfo->dreq; 741 742 spin_lock(&dreq->lock); 743 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 744 spin_unlock(&dreq->lock); 745 nfs_mark_request_commit(req, NULL, cinfo, 0); 746 } 747 748 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = { 749 .completion = nfs_direct_commit_complete, 750 .resched_write = nfs_direct_resched_write, 751 }; 752 753 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) 754 { 755 int res; 756 struct nfs_commit_info cinfo; 757 LIST_HEAD(mds_list); 758 759 nfs_init_cinfo_from_dreq(&cinfo, dreq); 760 nfs_scan_commit(dreq->inode, &mds_list, &cinfo); 761 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo); 762 if (res < 0) /* res == -ENOMEM */ 763 nfs_direct_write_reschedule(dreq); 764 } 765 766 static void nfs_direct_write_schedule_work(struct work_struct *work) 767 { 768 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work); 769 int flags = dreq->flags; 770 771 dreq->flags = 0; 772 switch (flags) { 773 case NFS_ODIRECT_DO_COMMIT: 774 nfs_direct_commit_schedule(dreq); 775 break; 776 case NFS_ODIRECT_RESCHED_WRITES: 777 nfs_direct_write_reschedule(dreq); 778 break; 779 default: 780 nfs_direct_complete(dreq, true); 781 } 782 } 783 784 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode) 785 { 786 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */ 787 } 788 789 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) 790 { 791 struct nfs_direct_req *dreq = hdr->dreq; 792 struct nfs_commit_info cinfo; 793 bool request_commit = false; 794 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 795 796 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 797 goto out_put; 798 799 nfs_init_cinfo_from_dreq(&cinfo, dreq); 800 801 spin_lock(&dreq->lock); 802 803 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 804 dreq->flags = 0; 805 dreq->error = hdr->error; 806 } 807 if (dreq->error == 0) { 808 nfs_direct_good_bytes(dreq, hdr); 809 if (nfs_write_need_commit(hdr)) { 810 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) 811 request_commit = true; 812 else if (dreq->flags == 0) { 813 nfs_direct_set_hdr_verf(dreq, hdr); 814 request_commit = true; 815 dreq->flags = NFS_ODIRECT_DO_COMMIT; 816 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) { 817 request_commit = true; 818 if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr)) 819 dreq->flags = 820 NFS_ODIRECT_RESCHED_WRITES; 821 } 822 } 823 } 824 spin_unlock(&dreq->lock); 825 826 while (!list_empty(&hdr->pages)) { 827 828 req = nfs_list_entry(hdr->pages.next); 829 nfs_list_remove_request(req); 830 if (request_commit) { 831 kref_get(&req->wb_kref); 832 nfs_mark_request_commit(req, hdr->lseg, &cinfo, 833 hdr->ds_commit_idx); 834 } 835 nfs_unlock_and_release_request(req); 836 } 837 838 out_put: 839 if (put_dreq(dreq)) 840 nfs_direct_write_complete(dreq, hdr->inode); 841 hdr->release(hdr); 842 } 843 844 static void nfs_write_sync_pgio_error(struct list_head *head) 845 { 846 struct nfs_page *req; 847 848 while (!list_empty(head)) { 849 req = nfs_list_entry(head->next); 850 nfs_list_remove_request(req); 851 nfs_unlock_and_release_request(req); 852 } 853 } 854 855 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr) 856 { 857 struct nfs_direct_req *dreq = hdr->dreq; 858 859 spin_lock(&dreq->lock); 860 if (dreq->error == 0) { 861 dreq->flags = NFS_ODIRECT_RESCHED_WRITES; 862 /* fake unstable write to let common nfs resend pages */ 863 hdr->verf.committed = NFS_UNSTABLE; 864 hdr->good_bytes = hdr->args.count; 865 } 866 spin_unlock(&dreq->lock); 867 } 868 869 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = { 870 .error_cleanup = nfs_write_sync_pgio_error, 871 .init_hdr = nfs_direct_pgio_init, 872 .completion = nfs_direct_write_completion, 873 .reschedule_io = nfs_direct_write_reschedule_io, 874 }; 875 876 877 /* 878 * NB: Return the value of the first error return code. Subsequent 879 * errors after the first one are ignored. 880 */ 881 /* 882 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE 883 * operation. If nfs_writedata_alloc() or get_user_pages() fails, 884 * bail and stop sending more writes. Write length accounting is 885 * handled automatically by nfs_direct_write_result(). Otherwise, if 886 * no requests have been sent, just return an error. 887 */ 888 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq, 889 struct iov_iter *iter, 890 loff_t pos) 891 { 892 struct nfs_pageio_descriptor desc; 893 struct inode *inode = dreq->inode; 894 ssize_t result = 0; 895 size_t requested_bytes = 0; 896 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE); 897 898 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false, 899 &nfs_direct_write_completion_ops); 900 desc.pg_dreq = dreq; 901 get_dreq(dreq); 902 inode_dio_begin(inode); 903 904 NFS_I(inode)->write_io += iov_iter_count(iter); 905 while (iov_iter_count(iter)) { 906 struct page **pagevec; 907 size_t bytes; 908 size_t pgbase; 909 unsigned npages, i; 910 911 result = iov_iter_get_pages_alloc(iter, &pagevec, 912 wsize, &pgbase); 913 if (result < 0) 914 break; 915 916 bytes = result; 917 iov_iter_advance(iter, bytes); 918 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; 919 for (i = 0; i < npages; i++) { 920 struct nfs_page *req; 921 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); 922 923 req = nfs_create_request(dreq->ctx, pagevec[i], NULL, 924 pgbase, req_len); 925 if (IS_ERR(req)) { 926 result = PTR_ERR(req); 927 break; 928 } 929 930 nfs_direct_setup_mirroring(dreq, &desc, req); 931 if (desc.pg_error < 0) { 932 nfs_free_request(req); 933 result = desc.pg_error; 934 break; 935 } 936 937 nfs_lock_request(req); 938 req->wb_index = pos >> PAGE_SHIFT; 939 req->wb_offset = pos & ~PAGE_MASK; 940 if (!nfs_pageio_add_request(&desc, req)) { 941 result = desc.pg_error; 942 nfs_unlock_and_release_request(req); 943 break; 944 } 945 pgbase = 0; 946 bytes -= req_len; 947 requested_bytes += req_len; 948 pos += req_len; 949 dreq->bytes_left -= req_len; 950 } 951 nfs_direct_release_pages(pagevec, npages); 952 kvfree(pagevec); 953 if (result < 0) 954 break; 955 } 956 nfs_pageio_complete(&desc); 957 958 /* 959 * If no bytes were started, return the error, and let the 960 * generic layer handle the completion. 961 */ 962 if (requested_bytes == 0) { 963 inode_dio_end(inode); 964 nfs_direct_req_release(dreq); 965 return result < 0 ? result : -EIO; 966 } 967 968 if (put_dreq(dreq)) 969 nfs_direct_write_complete(dreq, dreq->inode); 970 return 0; 971 } 972 973 /** 974 * nfs_file_direct_write - file direct write operation for NFS files 975 * @iocb: target I/O control block 976 * @iter: vector of user buffers from which to write data 977 * 978 * We use this function for direct writes instead of calling 979 * generic_file_aio_write() in order to avoid taking the inode 980 * semaphore and updating the i_size. The NFS server will set 981 * the new i_size and this client must read the updated size 982 * back into its cache. We let the server do generic write 983 * parameter checking and report problems. 984 * 985 * We eliminate local atime updates, see direct read above. 986 * 987 * We avoid unnecessary page cache invalidations for normal cached 988 * readers of this file. 989 * 990 * Note that O_APPEND is not supported for NFS direct writes, as there 991 * is no atomic O_APPEND write facility in the NFS protocol. 992 */ 993 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter) 994 { 995 ssize_t result = -EINVAL; 996 struct file *file = iocb->ki_filp; 997 struct address_space *mapping = file->f_mapping; 998 struct inode *inode = mapping->host; 999 struct nfs_direct_req *dreq; 1000 struct nfs_lock_context *l_ctx; 1001 loff_t pos, end; 1002 1003 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", 1004 file, iov_iter_count(iter), (long long) iocb->ki_pos); 1005 1006 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, 1007 iov_iter_count(iter)); 1008 1009 pos = iocb->ki_pos; 1010 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT; 1011 1012 inode_lock(inode); 1013 1014 result = nfs_sync_mapping(mapping); 1015 if (result) 1016 goto out_unlock; 1017 1018 if (mapping->nrpages) { 1019 result = invalidate_inode_pages2_range(mapping, 1020 pos >> PAGE_SHIFT, end); 1021 if (result) 1022 goto out_unlock; 1023 } 1024 1025 task_io_account_write(iov_iter_count(iter)); 1026 1027 result = -ENOMEM; 1028 dreq = nfs_direct_req_alloc(); 1029 if (!dreq) 1030 goto out_unlock; 1031 1032 dreq->inode = inode; 1033 dreq->bytes_left = dreq->max_count = iov_iter_count(iter); 1034 dreq->io_start = pos; 1035 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); 1036 l_ctx = nfs_get_lock_context(dreq->ctx); 1037 if (IS_ERR(l_ctx)) { 1038 result = PTR_ERR(l_ctx); 1039 goto out_release; 1040 } 1041 dreq->l_ctx = l_ctx; 1042 if (!is_sync_kiocb(iocb)) 1043 dreq->iocb = iocb; 1044 1045 result = nfs_direct_write_schedule_iovec(dreq, iter, pos); 1046 1047 if (mapping->nrpages) { 1048 invalidate_inode_pages2_range(mapping, 1049 pos >> PAGE_SHIFT, end); 1050 } 1051 1052 inode_unlock(inode); 1053 1054 if (!result) { 1055 result = nfs_direct_wait(dreq); 1056 if (result > 0) { 1057 struct inode *inode = mapping->host; 1058 1059 iocb->ki_pos = pos + result; 1060 spin_lock(&inode->i_lock); 1061 if (i_size_read(inode) < iocb->ki_pos) 1062 i_size_write(inode, iocb->ki_pos); 1063 spin_unlock(&inode->i_lock); 1064 1065 /* XXX: should check the generic_write_sync retval */ 1066 generic_write_sync(iocb, result); 1067 } 1068 } 1069 nfs_direct_req_release(dreq); 1070 return result; 1071 1072 out_release: 1073 nfs_direct_req_release(dreq); 1074 out_unlock: 1075 inode_unlock(inode); 1076 return result; 1077 } 1078 1079 /** 1080 * nfs_init_directcache - create a slab cache for nfs_direct_req structures 1081 * 1082 */ 1083 int __init nfs_init_directcache(void) 1084 { 1085 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache", 1086 sizeof(struct nfs_direct_req), 1087 0, (SLAB_RECLAIM_ACCOUNT| 1088 SLAB_MEM_SPREAD), 1089 NULL); 1090 if (nfs_direct_cachep == NULL) 1091 return -ENOMEM; 1092 1093 return 0; 1094 } 1095 1096 /** 1097 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures 1098 * 1099 */ 1100 void nfs_destroy_directcache(void) 1101 { 1102 kmem_cache_destroy(nfs_direct_cachep); 1103 } 1104