fs/nfs/direct.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/direct.c
   4  *
   5  * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
   6  *
   7  * High-performance uncached I/O for the Linux NFS client
   8  *
   9  * There are important applications whose performance or correctness
  10  * depends on uncached access to file data.  Database clusters
  11  * (multiple copies of the same instance running on separate hosts)
  12  * implement their own cache coherency protocol that subsumes file
  13  * system cache protocols.  Applications that process datasets
  14  * considerably larger than the client's memory do not always benefit
  15  * from a local cache.  A streaming video server, for instance, has no
  16  * need to cache the contents of a file.
  17  *
  18  * When an application requests uncached I/O, all read and write requests
  19  * are made directly to the server; data stored or fetched via these
  20  * requests is not cached in the Linux page cache.  The client does not
  21  * correct unaligned requests from applications.  All requested bytes are
  22  * held on permanent storage before a direct write system call returns to
  23  * an application.
  24  *
  25  * Solaris implements an uncached I/O facility called directio() that
  26  * is used for backups and sequential I/O to very large files.  Solaris
  27  * also supports uncaching whole NFS partitions with "-o forcedirectio,"
  28  * an undocumented mount option.
  29  *
  30  * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
  31  * help from Andrew Morton.
  32  *
  33  * 18 Dec 2001  Initial implementation for 2.4  --cel
  34  * 08 Jul 2002  Version for 2.4.19, with bug fixes --trondmy
  35  * 08 Jun 2003  Port to 2.5 APIs  --cel
  36  * 31 Mar 2004  Handle direct I/O without VFS support  --cel
  37  * 15 Sep 2004  Parallel async reads  --cel
  38  * 04 May 2005  support O_DIRECT with aio  --cel
  39  *
  40  */
  41
  42 #include <linux/errno.h>
  43 #include <linux/sched.h>
  44 #include <linux/kernel.h>
  45 #include <linux/file.h>
  46 #include <linux/pagemap.h>
  47 #include <linux/kref.h>
  48 #include <linux/slab.h>
  49 #include <linux/task_io_accounting_ops.h>
  50 #include <linux/module.h>
  51
  52 #include <linux/nfs_fs.h>
  53 #include <linux/nfs_page.h>
  54 #include <linux/sunrpc/clnt.h>
  55
  56 #include <linux/uaccess.h>
  57 #include <linux/atomic.h>
  58
  59 #include "internal.h"
  60 #include "iostat.h"
  61 #include "pnfs.h"
  62 #include "fscache.h"
  63 #include "nfstrace.h"
  64
  65 #define NFSDBG_FACILITY         NFSDBG_VFS
  66
  67 static struct kmem_cache *nfs_direct_cachep;
  68
  69 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
  70 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
  71 static void nfs_direct_write_complete(struct nfs_direct_req *dreq);
  72 static void nfs_direct_write_schedule_work(struct work_struct *work);
  73
  74 static inline void get_dreq(struct nfs_direct_req *dreq)
  75 {
  76         atomic_inc(&dreq->io_count);
  77 }
  78
  79 static inline int put_dreq(struct nfs_direct_req *dreq)
  80 {
  81         return atomic_dec_and_test(&dreq->io_count);
  82 }
  83
  84 static void
  85 nfs_direct_handle_truncated(struct nfs_direct_req *dreq,
  86                             const struct nfs_pgio_header *hdr,
  87                             ssize_t dreq_len)
  88 {
  89         if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||
  90               test_bit(NFS_IOHDR_EOF, &hdr->flags)))
  91                 return;
  92         if (dreq->max_count >= dreq_len) {
  93                 dreq->max_count = dreq_len;
  94                 if (dreq->count > dreq_len)
  95                         dreq->count = dreq_len;
  96
  97                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
  98                         dreq->error = hdr->error;
  99                 else /* Clear outstanding error if this is EOF */
 100                         dreq->error = 0;
 101         }
 102 }
 103
 104 static void
 105 nfs_direct_count_bytes(struct nfs_direct_req *dreq,
 106                        const struct nfs_pgio_header *hdr)
 107 {
 108         loff_t hdr_end = hdr->io_start + hdr->good_bytes;
 109         ssize_t dreq_len = 0;
 110
 111         if (hdr_end > dreq->io_start)
 112                 dreq_len = hdr_end - dreq->io_start;
 113
 114         nfs_direct_handle_truncated(dreq, hdr, dreq_len);
 115
 116         if (dreq_len > dreq->max_count)
 117                 dreq_len = dreq->max_count;
 118
 119         if (dreq->count < dreq_len)
 120                 dreq->count = dreq_len;
 121 }
 122
 123 /**
 124  * nfs_swap_rw - NFS address space operation for swap I/O
 125  * @iocb: target I/O control block
 126  * @iter: I/O buffer
 127  *
 128  * Perform IO to the swap-file.  This is much like direct IO.
 129  */
 130 int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
 131 {
 132         ssize_t ret;
 133
 134         VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE);
 135
 136         if (iov_iter_rw(iter) == READ)
 137                 ret = nfs_file_direct_read(iocb, iter, true);
 138         else
 139                 ret = nfs_file_direct_write(iocb, iter, true);
 140         if (ret < 0)
 141                 return ret;
 142         return 0;
 143 }
 144
 145 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
 146 {
 147         unsigned int i;
 148         for (i = 0; i < npages; i++)
 149                 put_page(pages[i]);
 150 }
 151
 152 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
 153                               struct nfs_direct_req *dreq)
 154 {
 155         cinfo->inode = dreq->inode;
 156         cinfo->mds = &dreq->mds_cinfo;
 157         cinfo->ds = &dreq->ds_cinfo;
 158         cinfo->dreq = dreq;
 159         cinfo->completion_ops = &nfs_direct_commit_completion_ops;
 160 }
 161
 162 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
 163 {
 164         struct nfs_direct_req *dreq;
 165
 166         dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
 167         if (!dreq)
 168                 return NULL;
 169
 170         kref_init(&dreq->kref);
 171         kref_get(&dreq->kref);
 172         init_completion(&dreq->completion);
 173         INIT_LIST_HEAD(&dreq->mds_cinfo.list);
 174         pnfs_init_ds_commit_info(&dreq->ds_cinfo);
 175         INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
 176         spin_lock_init(&dreq->lock);
 177
 178         return dreq;
 179 }
 180
 181 static void nfs_direct_req_free(struct kref *kref)
 182 {
 183         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
 184
 185         pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode);
 186         if (dreq->l_ctx != NULL)
 187                 nfs_put_lock_context(dreq->l_ctx);
 188         if (dreq->ctx != NULL)
 189                 put_nfs_open_context(dreq->ctx);
 190         kmem_cache_free(nfs_direct_cachep, dreq);
 191 }
 192
 193 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
 194 {
 195         kref_put(&dreq->kref, nfs_direct_req_free);
 196 }
 197
 198 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset)
 199 {
 200         loff_t start = offset - dreq->io_start;
 201         return dreq->max_count - start;
 202 }
 203 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
 204
 205 /*
 206  * Collects and returns the final error value/byte-count.
 207  */
 208 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
 209 {
 210         ssize_t result = -EIOCBQUEUED;
 211
 212         /* Async requests don't wait here */
 213         if (dreq->iocb)
 214                 goto out;
 215
 216         result = wait_for_completion_killable(&dreq->completion);
 217
 218         if (!result) {
 219                 result = dreq->count;
 220                 WARN_ON_ONCE(dreq->count < 0);
 221         }
 222         if (!result)
 223                 result = dreq->error;
 224
 225 out:
 226         return (ssize_t) result;
 227 }
 228
 229 /*
 230  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
 231  * the iocb is still valid here if this is a synchronous request.
 232  */
 233 static void nfs_direct_complete(struct nfs_direct_req *dreq)
 234 {
 235         struct inode *inode = dreq->inode;
 236
 237         inode_dio_end(inode);
 238
 239         if (dreq->iocb) {
 240                 long res = (long) dreq->error;
 241                 if (dreq->count != 0) {
 242                         res = (long) dreq->count;
 243                         WARN_ON_ONCE(dreq->count < 0);
 244                 }
 245                 dreq->iocb->ki_complete(dreq->iocb, res);
 246         }
 247
 248         complete(&dreq->completion);
 249
 250         nfs_direct_req_release(dreq);
 251 }
 252
 253 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
 254 {
 255         unsigned long bytes = 0;
 256         struct nfs_direct_req *dreq = hdr->dreq;
 257
 258         spin_lock(&dreq->lock);
 259         if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
 260                 spin_unlock(&dreq->lock);
 261                 goto out_put;
 262         }
 263
 264         nfs_direct_count_bytes(dreq, hdr);
 265         spin_unlock(&dreq->lock);
 266
 267         while (!list_empty(&hdr->pages)) {
 268                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 269                 struct page *page = req->wb_page;
 270
 271                 if (!PageCompound(page) && bytes < hdr->good_bytes &&
 272                     (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
 273                         set_page_dirty(page);
 274                 bytes += req->wb_bytes;
 275                 nfs_list_remove_request(req);
 276                 nfs_release_request(req);
 277         }
 278 out_put:
 279         if (put_dreq(dreq))
 280                 nfs_direct_complete(dreq);
 281         hdr->release(hdr);
 282 }
 283
 284 static void nfs_read_sync_pgio_error(struct list_head *head, int error)
 285 {
 286         struct nfs_page *req;
 287
 288         while (!list_empty(head)) {
 289                 req = nfs_list_entry(head->next);
 290                 nfs_list_remove_request(req);
 291                 nfs_release_request(req);
 292         }
 293 }
 294
 295 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
 296 {
 297         get_dreq(hdr->dreq);
 298 }
 299
 300 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
 301         .error_cleanup = nfs_read_sync_pgio_error,
 302         .init_hdr = nfs_direct_pgio_init,
 303         .completion = nfs_direct_read_completion,
 304 };
 305
 306 /*
 307  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
 308  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
 309  * bail and stop sending more reads.  Read length accounting is
 310  * handled automatically by nfs_direct_read_result().  Otherwise, if
 311  * no requests have been sent, just return an error.
 312  */
 313
 314 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 315                                               struct iov_iter *iter,
 316                                               loff_t pos)
 317 {
 318         struct nfs_pageio_descriptor desc;
 319         struct inode *inode = dreq->inode;
 320         ssize_t result = -EINVAL;
 321         size_t requested_bytes = 0;
 322         size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
 323
 324         nfs_pageio_init_read(&desc, dreq->inode, false,
 325                              &nfs_direct_read_completion_ops);
 326         get_dreq(dreq);
 327         desc.pg_dreq = dreq;
 328         inode_dio_begin(inode);
 329
 330         while (iov_iter_count(iter)) {
 331                 struct page **pagevec;
 332                 size_t bytes;
 333                 size_t pgbase;
 334                 unsigned npages, i;
 335
 336                 result = iov_iter_get_pages_alloc2(iter, &pagevec,
 337                                                   rsize, &pgbase);
 338                 if (result < 0)
 339                         break;
 340
 341                 bytes = result;
 342                 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
 343                 for (i = 0; i < npages; i++) {
 344                         struct nfs_page *req;
 345                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 346                         /* XXX do we need to do the eof zeroing found in async_filler? */
 347                         req = nfs_create_request(dreq->ctx, pagevec[i],
 348                                                  pgbase, req_len);
 349                         if (IS_ERR(req)) {
 350                                 result = PTR_ERR(req);
 351                                 break;
 352                         }
 353                         req->wb_index = pos >> PAGE_SHIFT;
 354                         req->wb_offset = pos & ~PAGE_MASK;
 355                         if (!nfs_pageio_add_request(&desc, req)) {
 356                                 result = desc.pg_error;
 357                                 nfs_release_request(req);
 358                                 break;
 359                         }
 360                         pgbase = 0;
 361                         bytes -= req_len;
 362                         requested_bytes += req_len;
 363                         pos += req_len;
 364                         dreq->bytes_left -= req_len;
 365                 }
 366                 nfs_direct_release_pages(pagevec, npages);
 367                 kvfree(pagevec);
 368                 if (result < 0)
 369                         break;
 370         }
 371
 372         nfs_pageio_complete(&desc);
 373
 374         /*
 375          * If no bytes were started, return the error, and let the
 376          * generic layer handle the completion.
 377          */
 378         if (requested_bytes == 0) {
 379                 inode_dio_end(inode);
 380                 nfs_direct_req_release(dreq);
 381                 return result < 0 ? result : -EIO;
 382         }
 383
 384         if (put_dreq(dreq))
 385                 nfs_direct_complete(dreq);
 386         return requested_bytes;
 387 }
 388
 389 /**
 390  * nfs_file_direct_read - file direct read operation for NFS files
 391  * @iocb: target I/O control block
 392  * @iter: vector of user buffers into which to read data
 393  * @swap: flag indicating this is swap IO, not O_DIRECT IO
 394  *
 395  * We use this function for direct reads instead of calling
 396  * generic_file_aio_read() in order to avoid gfar's check to see if
 397  * the request starts before the end of the file.  For that check
 398  * to work, we must generate a GETATTR before each direct read, and
 399  * even then there is a window between the GETATTR and the subsequent
 400  * READ where the file size could change.  Our preference is simply
 401  * to do all reads the application wants, and the server will take
 402  * care of managing the end of file boundary.
 403  *
 404  * This function also eliminates unnecessarily updating the file's
 405  * atime locally, as the NFS server sets the file's atime, and this
 406  * client must read the updated atime from the server back into its
 407  * cache.
 408  */
 409 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter,
 410                              bool swap)
 411 {
 412         struct file *file = iocb->ki_filp;
 413         struct address_space *mapping = file->f_mapping;
 414         struct inode *inode = mapping->host;
 415         struct nfs_direct_req *dreq;
 416         struct nfs_lock_context *l_ctx;
 417         ssize_t result, requested;
 418         size_t count = iov_iter_count(iter);
 419         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 420
 421         dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
 422                 file, count, (long long) iocb->ki_pos);
 423
 424         result = 0;
 425         if (!count)
 426                 goto out;
 427
 428         task_io_account_read(count);
 429
 430         result = -ENOMEM;
 431         dreq = nfs_direct_req_alloc();
 432         if (dreq == NULL)
 433                 goto out;
 434
 435         dreq->inode = inode;
 436         dreq->bytes_left = dreq->max_count = count;
 437         dreq->io_start = iocb->ki_pos;
 438         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 439         l_ctx = nfs_get_lock_context(dreq->ctx);
 440         if (IS_ERR(l_ctx)) {
 441                 result = PTR_ERR(l_ctx);
 442                 nfs_direct_req_release(dreq);
 443                 goto out_release;
 444         }
 445         dreq->l_ctx = l_ctx;
 446         if (!is_sync_kiocb(iocb))
 447                 dreq->iocb = iocb;
 448
 449         if (user_backed_iter(iter))
 450                 dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
 451
 452         if (!swap)
 453                 nfs_start_io_direct(inode);
 454
 455         NFS_I(inode)->read_io += count;
 456         requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
 457
 458         if (!swap)
 459                 nfs_end_io_direct(inode);
 460
 461         if (requested > 0) {
 462                 result = nfs_direct_wait(dreq);
 463                 if (result > 0) {
 464                         requested -= result;
 465                         iocb->ki_pos += result;
 466                 }
 467                 iov_iter_revert(iter, requested);
 468         } else {
 469                 result = requested;
 470         }
 471
 472 out_release:
 473         nfs_direct_req_release(dreq);
 474 out:
 475         return result;
 476 }
 477
 478 static void nfs_direct_add_page_head(struct list_head *list,
 479                                      struct nfs_page *req)
 480 {
 481         struct nfs_page *head = req->wb_head;
 482
 483         if (!list_empty(&head->wb_list) || !nfs_lock_request(head))
 484                 return;
 485         if (!list_empty(&head->wb_list)) {
 486                 nfs_unlock_request(head);
 487                 return;
 488         }
 489         list_add(&head->wb_list, list);
 490         kref_get(&head->wb_kref);
 491         kref_get(&head->wb_kref);
 492 }
 493
 494 static void nfs_direct_join_group(struct list_head *list, struct inode *inode)
 495 {
 496         struct nfs_page *req, *subreq;
 497
 498         list_for_each_entry(req, list, wb_list) {
 499                 if (req->wb_head != req) {
 500                         nfs_direct_add_page_head(&req->wb_list, req);
 501                         continue;
 502                 }
 503                 subreq = req->wb_this_page;
 504                 if (subreq == req)
 505                         continue;
 506                 do {
 507                         /*
 508                          * Remove subrequests from this list before freeing
 509                          * them in the call to nfs_join_page_group().
 510                          */
 511                         if (!list_empty(&subreq->wb_list)) {
 512                                 nfs_list_remove_request(subreq);
 513                                 nfs_release_request(subreq);
 514                         }
 515                 } while ((subreq = subreq->wb_this_page) != req);
 516                 nfs_join_page_group(req, inode);
 517         }
 518 }
 519
 520 static void
 521 nfs_direct_write_scan_commit_list(struct inode *inode,
 522                                   struct list_head *list,
 523                                   struct nfs_commit_info *cinfo)
 524 {
 525         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 526         pnfs_recover_commit_reqs(list, cinfo);
 527         nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
 528         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 529 }
 530
 531 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 532 {
 533         struct nfs_pageio_descriptor desc;
 534         struct nfs_page *req, *tmp;
 535         LIST_HEAD(reqs);
 536         struct nfs_commit_info cinfo;
 537         LIST_HEAD(failed);
 538
 539         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 540         nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
 541
 542         nfs_direct_join_group(&reqs, dreq->inode);
 543
 544         dreq->count = 0;
 545         dreq->max_count = 0;
 546         list_for_each_entry(req, &reqs, wb_list)
 547                 dreq->max_count += req->wb_bytes;
 548         nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
 549         get_dreq(dreq);
 550
 551         nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
 552                               &nfs_direct_write_completion_ops);
 553         desc.pg_dreq = dreq;
 554
 555         list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
 556                 /* Bump the transmission count */
 557                 req->wb_nio++;
 558                 if (!nfs_pageio_add_request(&desc, req)) {
 559                         nfs_list_move_request(req, &failed);
 560                         spin_lock(&cinfo.inode->i_lock);
 561                         dreq->flags = 0;
 562                         if (desc.pg_error < 0)
 563                                 dreq->error = desc.pg_error;
 564                         else
 565                                 dreq->error = -EIO;
 566                         spin_unlock(&cinfo.inode->i_lock);
 567                 }
 568                 nfs_release_request(req);
 569         }
 570         nfs_pageio_complete(&desc);
 571
 572         while (!list_empty(&failed)) {
 573                 req = nfs_list_entry(failed.next);
 574                 nfs_list_remove_request(req);
 575                 nfs_unlock_and_release_request(req);
 576         }
 577
 578         if (put_dreq(dreq))
 579                 nfs_direct_write_complete(dreq);
 580 }
 581
 582 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
 583 {
 584         const struct nfs_writeverf *verf = data->res.verf;
 585         struct nfs_direct_req *dreq = data->dreq;
 586         struct nfs_commit_info cinfo;
 587         struct nfs_page *req;
 588         int status = data->task.tk_status;
 589
 590         trace_nfs_direct_commit_complete(dreq);
 591
 592         if (status < 0) {
 593                 /* Errors in commit are fatal */
 594                 dreq->error = status;
 595                 dreq->max_count = 0;
 596                 dreq->count = 0;
 597                 dreq->flags = NFS_ODIRECT_DONE;
 598         } else {
 599                 status = dreq->error;
 600         }
 601
 602         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 603
 604         while (!list_empty(&data->pages)) {
 605                 req = nfs_list_entry(data->pages.next);
 606                 nfs_list_remove_request(req);
 607                 if (status >= 0 && !nfs_write_match_verf(verf, req)) {
 608                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 609                         /*
 610                          * Despite the reboot, the write was successful,
 611                          * so reset wb_nio.
 612                          */
 613                         req->wb_nio = 0;
 614                         nfs_mark_request_commit(req, NULL, &cinfo, 0);
 615                 } else /* Error or match */
 616                         nfs_release_request(req);
 617                 nfs_unlock_and_release_request(req);
 618         }
 619
 620         if (nfs_commit_end(cinfo.mds))
 621                 nfs_direct_write_complete(dreq);
 622 }
 623
 624 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
 625                 struct nfs_page *req)
 626 {
 627         struct nfs_direct_req *dreq = cinfo->dreq;
 628
 629         trace_nfs_direct_resched_write(dreq);
 630
 631         spin_lock(&dreq->lock);
 632         if (dreq->flags != NFS_ODIRECT_DONE)
 633                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 634         spin_unlock(&dreq->lock);
 635         nfs_mark_request_commit(req, NULL, cinfo, 0);
 636 }
 637
 638 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
 639         .completion = nfs_direct_commit_complete,
 640         .resched_write = nfs_direct_resched_write,
 641 };
 642
 643 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 644 {
 645         int res;
 646         struct nfs_commit_info cinfo;
 647         LIST_HEAD(mds_list);
 648
 649         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 650         nfs_commit_begin(cinfo.mds);
 651         nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
 652         res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
 653         if (res < 0) { /* res == -ENOMEM */
 654                 spin_lock(&dreq->lock);
 655                 if (dreq->flags == 0)
 656                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 657                 spin_unlock(&dreq->lock);
 658         }
 659         if (nfs_commit_end(cinfo.mds))
 660                 nfs_direct_write_complete(dreq);
 661 }
 662
 663 static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)
 664 {
 665         struct nfs_commit_info cinfo;
 666         struct nfs_page *req;
 667         LIST_HEAD(reqs);
 668
 669         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 670         nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
 671
 672         while (!list_empty(&reqs)) {
 673                 req = nfs_list_entry(reqs.next);
 674                 nfs_list_remove_request(req);
 675                 nfs_release_request(req);
 676                 nfs_unlock_and_release_request(req);
 677         }
 678 }
 679
 680 static void nfs_direct_write_schedule_work(struct work_struct *work)
 681 {
 682         struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
 683         int flags = dreq->flags;
 684
 685         dreq->flags = 0;
 686         switch (flags) {
 687                 case NFS_ODIRECT_DO_COMMIT:
 688                         nfs_direct_commit_schedule(dreq);
 689                         break;
 690                 case NFS_ODIRECT_RESCHED_WRITES:
 691                         nfs_direct_write_reschedule(dreq);
 692                         break;
 693                 default:
 694                         nfs_direct_write_clear_reqs(dreq);
 695                         nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
 696                         nfs_direct_complete(dreq);
 697         }
 698 }
 699
 700 static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
 701 {
 702         trace_nfs_direct_write_complete(dreq);
 703         queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */
 704 }
 705
 706 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 707 {
 708         struct nfs_direct_req *dreq = hdr->dreq;
 709         struct nfs_commit_info cinfo;
 710         struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 711         int flags = NFS_ODIRECT_DONE;
 712
 713         trace_nfs_direct_write_completion(dreq);
 714
 715         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 716
 717         spin_lock(&dreq->lock);
 718         if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
 719                 spin_unlock(&dreq->lock);
 720                 goto out_put;
 721         }
 722
 723         nfs_direct_count_bytes(dreq, hdr);
 724         if (test_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags)) {
 725                 if (!dreq->flags)
 726                         dreq->flags = NFS_ODIRECT_DO_COMMIT;
 727                 flags = dreq->flags;
 728         }
 729         spin_unlock(&dreq->lock);
 730
 731         while (!list_empty(&hdr->pages)) {
 732
 733                 req = nfs_list_entry(hdr->pages.next);
 734                 nfs_list_remove_request(req);
 735                 if (flags == NFS_ODIRECT_DO_COMMIT) {
 736                         kref_get(&req->wb_kref);
 737                         memcpy(&req->wb_verf, &hdr->verf.verifier,
 738                                sizeof(req->wb_verf));
 739                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
 740                                 hdr->ds_commit_idx);
 741                 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
 742                         kref_get(&req->wb_kref);
 743                         nfs_mark_request_commit(req, NULL, &cinfo, 0);
 744                 }
 745                 nfs_unlock_and_release_request(req);
 746         }
 747
 748 out_put:
 749         if (put_dreq(dreq))
 750                 nfs_direct_write_complete(dreq);
 751         hdr->release(hdr);
 752 }
 753
 754 static void nfs_write_sync_pgio_error(struct list_head *head, int error)
 755 {
 756         struct nfs_page *req;
 757
 758         while (!list_empty(head)) {
 759                 req = nfs_list_entry(head->next);
 760                 nfs_list_remove_request(req);
 761                 nfs_unlock_and_release_request(req);
 762         }
 763 }
 764
 765 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
 766 {
 767         struct nfs_direct_req *dreq = hdr->dreq;
 768
 769         trace_nfs_direct_write_reschedule_io(dreq);
 770
 771         spin_lock(&dreq->lock);
 772         if (dreq->error == 0) {
 773                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 774                 /* fake unstable write to let common nfs resend pages */
 775                 hdr->verf.committed = NFS_UNSTABLE;
 776                 hdr->good_bytes = hdr->args.offset + hdr->args.count -
 777                         hdr->io_start;
 778         }
 779         spin_unlock(&dreq->lock);
 780 }
 781
 782 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
 783         .error_cleanup = nfs_write_sync_pgio_error,
 784         .init_hdr = nfs_direct_pgio_init,
 785         .completion = nfs_direct_write_completion,
 786         .reschedule_io = nfs_direct_write_reschedule_io,
 787 };
 788
 789
 790 /*
 791  * NB: Return the value of the first error return code.  Subsequent
 792  *     errors after the first one are ignored.
 793  */
 794 /*
 795  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
 796  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
 797  * bail and stop sending more writes.  Write length accounting is
 798  * handled automatically by nfs_direct_write_result().  Otherwise, if
 799  * no requests have been sent, just return an error.
 800  */
 801 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 802                                                struct iov_iter *iter,
 803                                                loff_t pos, int ioflags)
 804 {
 805         struct nfs_pageio_descriptor desc;
 806         struct inode *inode = dreq->inode;
 807         ssize_t result = 0;
 808         size_t requested_bytes = 0;
 809         size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
 810
 811         trace_nfs_direct_write_schedule_iovec(dreq);
 812
 813         nfs_pageio_init_write(&desc, inode, ioflags, false,
 814                               &nfs_direct_write_completion_ops);
 815         desc.pg_dreq = dreq;
 816         get_dreq(dreq);
 817         inode_dio_begin(inode);
 818
 819         NFS_I(inode)->write_io += iov_iter_count(iter);
 820         while (iov_iter_count(iter)) {
 821                 struct page **pagevec;
 822                 size_t bytes;
 823                 size_t pgbase;
 824                 unsigned npages, i;
 825
 826                 result = iov_iter_get_pages_alloc2(iter, &pagevec,
 827                                                   wsize, &pgbase);
 828                 if (result < 0)
 829                         break;
 830
 831                 bytes = result;
 832                 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
 833                 for (i = 0; i < npages; i++) {
 834                         struct nfs_page *req;
 835                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 836
 837                         req = nfs_create_request(dreq->ctx, pagevec[i],
 838                                                  pgbase, req_len);
 839                         if (IS_ERR(req)) {
 840                                 result = PTR_ERR(req);
 841                                 break;
 842                         }
 843
 844                         if (desc.pg_error < 0) {
 845                                 nfs_free_request(req);
 846                                 result = desc.pg_error;
 847                                 break;
 848                         }
 849
 850                         nfs_lock_request(req);
 851                         req->wb_index = pos >> PAGE_SHIFT;
 852                         req->wb_offset = pos & ~PAGE_MASK;
 853                         if (!nfs_pageio_add_request(&desc, req)) {
 854                                 result = desc.pg_error;
 855                                 nfs_unlock_and_release_request(req);
 856                                 break;
 857                         }
 858                         pgbase = 0;
 859                         bytes -= req_len;
 860                         requested_bytes += req_len;
 861                         pos += req_len;
 862                         dreq->bytes_left -= req_len;
 863                 }
 864                 nfs_direct_release_pages(pagevec, npages);
 865                 kvfree(pagevec);
 866                 if (result < 0)
 867                         break;
 868         }
 869         nfs_pageio_complete(&desc);
 870
 871         /*
 872          * If no bytes were started, return the error, and let the
 873          * generic layer handle the completion.
 874          */
 875         if (requested_bytes == 0) {
 876                 inode_dio_end(inode);
 877                 nfs_direct_req_release(dreq);
 878                 return result < 0 ? result : -EIO;
 879         }
 880
 881         if (put_dreq(dreq))
 882                 nfs_direct_write_complete(dreq);
 883         return requested_bytes;
 884 }
 885
 886 /**
 887  * nfs_file_direct_write - file direct write operation for NFS files
 888  * @iocb: target I/O control block
 889  * @iter: vector of user buffers from which to write data
 890  * @swap: flag indicating this is swap IO, not O_DIRECT IO
 891  *
 892  * We use this function for direct writes instead of calling
 893  * generic_file_aio_write() in order to avoid taking the inode
 894  * semaphore and updating the i_size.  The NFS server will set
 895  * the new i_size and this client must read the updated size
 896  * back into its cache.  We let the server do generic write
 897  * parameter checking and report problems.
 898  *
 899  * We eliminate local atime updates, see direct read above.
 900  *
 901  * We avoid unnecessary page cache invalidations for normal cached
 902  * readers of this file.
 903  *
 904  * Note that O_APPEND is not supported for NFS direct writes, as there
 905  * is no atomic O_APPEND write facility in the NFS protocol.
 906  */
 907 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter,
 908                               bool swap)
 909 {
 910         ssize_t result, requested;
 911         size_t count;
 912         struct file *file = iocb->ki_filp;
 913         struct address_space *mapping = file->f_mapping;
 914         struct inode *inode = mapping->host;
 915         struct nfs_direct_req *dreq;
 916         struct nfs_lock_context *l_ctx;
 917         loff_t pos, end;
 918
 919         dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
 920                 file, iov_iter_count(iter), (long long) iocb->ki_pos);
 921
 922         if (swap)
 923                 /* bypass generic checks */
 924                 result =  iov_iter_count(iter);
 925         else
 926                 result = generic_write_checks(iocb, iter);
 927         if (result <= 0)
 928                 return result;
 929         count = result;
 930         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 931
 932         pos = iocb->ki_pos;
 933         end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
 934
 935         task_io_account_write(count);
 936
 937         result = -ENOMEM;
 938         dreq = nfs_direct_req_alloc();
 939         if (!dreq)
 940                 goto out;
 941
 942         dreq->inode = inode;
 943         dreq->bytes_left = dreq->max_count = count;
 944         dreq->io_start = pos;
 945         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 946         l_ctx = nfs_get_lock_context(dreq->ctx);
 947         if (IS_ERR(l_ctx)) {
 948                 result = PTR_ERR(l_ctx);
 949                 nfs_direct_req_release(dreq);
 950                 goto out_release;
 951         }
 952         dreq->l_ctx = l_ctx;
 953         if (!is_sync_kiocb(iocb))
 954                 dreq->iocb = iocb;
 955         pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode);
 956
 957         if (swap) {
 958                 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
 959                                                             FLUSH_STABLE);
 960         } else {
 961                 nfs_start_io_direct(inode);
 962
 963                 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
 964                                                             FLUSH_COND_STABLE);
 965
 966                 if (mapping->nrpages) {
 967                         invalidate_inode_pages2_range(mapping,
 968                                                       pos >> PAGE_SHIFT, end);
 969                 }
 970
 971                 nfs_end_io_direct(inode);
 972         }
 973
 974         if (requested > 0) {
 975                 result = nfs_direct_wait(dreq);
 976                 if (result > 0) {
 977                         requested -= result;
 978                         iocb->ki_pos = pos + result;
 979                         /* XXX: should check the generic_write_sync retval */
 980                         generic_write_sync(iocb, result);
 981                 }
 982                 iov_iter_revert(iter, requested);
 983         } else {
 984                 result = requested;
 985         }
 986         nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE);
 987 out_release:
 988         nfs_direct_req_release(dreq);
 989 out:
 990         return result;
 991 }
 992
 993 /**
 994  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
 995  *
 996  */
 997 int __init nfs_init_directcache(void)
 998 {
 999         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1000                                                 sizeof(struct nfs_direct_req),
1001                                                 0, (SLAB_RECLAIM_ACCOUNT|
1002                                                         SLAB_MEM_SPREAD),
1003                                                 NULL);
1004         if (nfs_direct_cachep == NULL)
1005                 return -ENOMEM;
1006
1007         return 0;
1008 }
1009
1010 /**
1011  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1012  *
1013  */
1014 void nfs_destroy_directcache(void)
1015 {
1016         kmem_cache_destroy(nfs_direct_cachep);
1017 }