root/fs/nfs/file.c

DEFINITIONS

1. nfs_check_flags
2. nfs_file_open
3. nfs_file_release
4. nfs_revalidate_file_size
5. nfs_file_llseek
6. nfs_file_flush
7. nfs_file_read
8. nfs_file_mmap
9. nfs_file_fsync_commit
10. nfs_file_fsync
11. nfs_full_page_write
12. nfs_want_read_modify_write
13. nfs_write_begin
14. nfs_write_end
15. nfs_invalidate_page
16. nfs_release_page
17. nfs_check_dirty_writeback
18. nfs_launder_page
19. nfs_swap_activate
20. nfs_swap_deactivate
21. nfs_vm_page_mkwrite
22. nfs_need_check_write
23. nfs_file_write
24. do_getlk
25. do_unlk
26. do_setlk
27. nfs_lock
28. nfs_flock

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/nfs/file.c
   4  *
   5  *  Copyright (C) 1992  Rick Sladkey
   6  *
   7  *  Changes Copyright (C) 1994 by Florian La Roche
   8  *   - Do not copy data too often around in the kernel.
   9  *   - In nfs_file_read the return value of kmalloc wasn't checked.
  10  *   - Put in a better version of read look-ahead buffering. Original idea
  11  *     and implementation by Wai S Kok elekokws@ee.nus.sg.
  12  *
  13  *  Expire cache on write to a file by Wai S Kok (Oct 1994).
  14  *
  15  *  Total rewrite of read side for new NFS buffer cache.. Linus.
  16  *
  17  *  nfs regular file handling functions
  18  */
  19 
  20 #include <linux/module.h>
  21 #include <linux/time.h>
  22 #include <linux/kernel.h>
  23 #include <linux/errno.h>
  24 #include <linux/fcntl.h>
  25 #include <linux/stat.h>
  26 #include <linux/nfs_fs.h>
  27 #include <linux/nfs_mount.h>
  28 #include <linux/mm.h>
  29 #include <linux/pagemap.h>
  30 #include <linux/gfp.h>
  31 #include <linux/swap.h>
  32 
  33 #include <linux/uaccess.h>
  34 
  35 #include "delegation.h"
  36 #include "internal.h"
  37 #include "iostat.h"
  38 #include "fscache.h"
  39 #include "pnfs.h"
  40 
  41 #include "nfstrace.h"
  42 
  43 #define NFSDBG_FACILITY         NFSDBG_FILE
  44 
  45 static const struct vm_operations_struct nfs_file_vm_ops;
  46 
  47 /* Hack for future NFS swap support */
  48 #ifndef IS_SWAPFILE
  49 # define IS_SWAPFILE(inode)     (0)
  50 #endif
  51 
  52 int nfs_check_flags(int flags)
  53 {
  54         if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
  55                 return -EINVAL;
  56 
  57         return 0;
  58 }
  59 EXPORT_SYMBOL_GPL(nfs_check_flags);
  60 
  61 /*
  62  * Open file
  63  */
  64 static int
  65 nfs_file_open(struct inode *inode, struct file *filp)
  66 {
  67         int res;
  68 
  69         dprintk("NFS: open file(%pD2)\n", filp);
  70 
  71         nfs_inc_stats(inode, NFSIOS_VFSOPEN);
  72         res = nfs_check_flags(filp->f_flags);
  73         if (res)
  74                 return res;
  75 
  76         res = nfs_open(inode, filp);
  77         return res;
  78 }
  79 
  80 int
  81 nfs_file_release(struct inode *inode, struct file *filp)
  82 {
  83         dprintk("NFS: release(%pD2)\n", filp);
  84 
  85         nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
  86         nfs_file_clear_open_context(filp);
  87         return 0;
  88 }
  89 EXPORT_SYMBOL_GPL(nfs_file_release);
  90 
  91 /**
  92  * nfs_revalidate_size - Revalidate the file size
  93  * @inode: pointer to inode struct
  94  * @filp: pointer to struct file
  95  *
  96  * Revalidates the file length. This is basically a wrapper around
  97  * nfs_revalidate_inode() that takes into account the fact that we may
  98  * have cached writes (in which case we don't care about the server's
  99  * idea of what the file length is), or O_DIRECT (in which case we
 100  * shouldn't trust the cache).
 101  */
 102 static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
 103 {
 104         struct nfs_server *server = NFS_SERVER(inode);
 105 
 106         if (filp->f_flags & O_DIRECT)
 107                 goto force_reval;
 108         if (nfs_check_cache_invalid(inode, NFS_INO_REVAL_PAGECACHE))
 109                 goto force_reval;
 110         return 0;
 111 force_reval:
 112         return __nfs_revalidate_inode(server, inode);
 113 }
 114 
 115 loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
 116 {
 117         dprintk("NFS: llseek file(%pD2, %lld, %d)\n",
 118                         filp, offset, whence);
 119 
 120         /*
 121          * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
 122          * the cached file length
 123          */
 124         if (whence != SEEK_SET && whence != SEEK_CUR) {
 125                 struct inode *inode = filp->f_mapping->host;
 126 
 127                 int retval = nfs_revalidate_file_size(inode, filp);
 128                 if (retval < 0)
 129                         return (loff_t)retval;
 130         }
 131 
 132         return generic_file_llseek(filp, offset, whence);
 133 }
 134 EXPORT_SYMBOL_GPL(nfs_file_llseek);
 135 
 136 /*
 137  * Flush all dirty pages, and check for write errors.
 138  */
 139 static int
 140 nfs_file_flush(struct file *file, fl_owner_t id)
 141 {
 142         struct inode    *inode = file_inode(file);
 143 
 144         dprintk("NFS: flush(%pD2)\n", file);
 145 
 146         nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
 147         if ((file->f_mode & FMODE_WRITE) == 0)
 148                 return 0;
 149 
 150         /* Flush writes to the server and return any errors */
 151         return nfs_wb_all(inode);
 152 }
 153 
 154 ssize_t
 155 nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
 156 {
 157         struct inode *inode = file_inode(iocb->ki_filp);
 158         ssize_t result;
 159 
 160         if (iocb->ki_flags & IOCB_DIRECT)
 161                 return nfs_file_direct_read(iocb, to);
 162 
 163         dprintk("NFS: read(%pD2, %zu@%lu)\n",
 164                 iocb->ki_filp,
 165                 iov_iter_count(to), (unsigned long) iocb->ki_pos);
 166 
 167         nfs_start_io_read(inode);
 168         result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
 169         if (!result) {
 170                 result = generic_file_read_iter(iocb, to);
 171                 if (result > 0)
 172                         nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
 173         }
 174         nfs_end_io_read(inode);
 175         return result;
 176 }
 177 EXPORT_SYMBOL_GPL(nfs_file_read);
 178 
 179 int
 180 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
 181 {
 182         struct inode *inode = file_inode(file);
 183         int     status;
 184 
 185         dprintk("NFS: mmap(%pD2)\n", file);
 186 
 187         /* Note: generic_file_mmap() returns ENOSYS on nommu systems
 188          *       so we call that before revalidating the mapping
 189          */
 190         status = generic_file_mmap(file, vma);
 191         if (!status) {
 192                 vma->vm_ops = &nfs_file_vm_ops;
 193                 status = nfs_revalidate_mapping(inode, file->f_mapping);
 194         }
 195         return status;
 196 }
 197 EXPORT_SYMBOL_GPL(nfs_file_mmap);
 198 
 199 /*
 200  * Flush any dirty pages for this process, and check for write errors.
 201  * The return status from this call provides a reliable indication of
 202  * whether any write errors occurred for this process.
 203  */
 204 static int
 205 nfs_file_fsync_commit(struct file *file, int datasync)
 206 {
 207         struct nfs_open_context *ctx = nfs_file_open_context(file);
 208         struct inode *inode = file_inode(file);
 209         int do_resend, status;
 210         int ret = 0;
 211 
 212         dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync);
 213 
 214         nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
 215         do_resend = test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
 216         status = nfs_commit_inode(inode, FLUSH_SYNC);
 217         if (status == 0)
 218                 status = file_check_and_advance_wb_err(file);
 219         if (status < 0) {
 220                 ret = status;
 221                 goto out;
 222         }
 223         do_resend |= test_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
 224         if (do_resend)
 225                 ret = -EAGAIN;
 226 out:
 227         return ret;
 228 }
 229 
 230 int
 231 nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 232 {
 233         int ret;
 234         struct inode *inode = file_inode(file);
 235 
 236         trace_nfs_fsync_enter(inode);
 237 
 238         do {
 239                 ret = file_write_and_wait_range(file, start, end);
 240                 if (ret != 0)
 241                         break;
 242                 ret = nfs_file_fsync_commit(file, datasync);
 243                 if (!ret)
 244                         ret = pnfs_sync_inode(inode, !!datasync);
 245                 /*
 246                  * If nfs_file_fsync_commit detected a server reboot, then
 247                  * resend all dirty pages that might have been covered by
 248                  * the NFS_CONTEXT_RESEND_WRITES flag
 249                  */
 250                 start = 0;
 251                 end = LLONG_MAX;
 252         } while (ret == -EAGAIN);
 253 
 254         trace_nfs_fsync_exit(inode, ret);
 255         return ret;
 256 }
 257 EXPORT_SYMBOL_GPL(nfs_file_fsync);
 258 
 259 /*
 260  * Decide whether a read/modify/write cycle may be more efficient
 261  * then a modify/write/read cycle when writing to a page in the
 262  * page cache.
 263  *
 264  * Some pNFS layout drivers can only read/write at a certain block
 265  * granularity like all block devices and therefore we must perform
 266  * read/modify/write whenever a page hasn't read yet and the data
 267  * to be written there is not aligned to a block boundary and/or
 268  * smaller than the block size.
 269  *
 270  * The modify/write/read cycle may occur if a page is read before
 271  * being completely filled by the writer.  In this situation, the
 272  * page must be completely written to stable storage on the server
 273  * before it can be refilled by reading in the page from the server.
 274  * This can lead to expensive, small, FILE_SYNC mode writes being
 275  * done.
 276  *
 277  * It may be more efficient to read the page first if the file is
 278  * open for reading in addition to writing, the page is not marked
 279  * as Uptodate, it is not dirty or waiting to be committed,
 280  * indicating that it was previously allocated and then modified,
 281  * that there were valid bytes of data in that range of the file,
 282  * and that the new data won't completely replace the old data in
 283  * that range of the file.
 284  */
 285 static bool nfs_full_page_write(struct page *page, loff_t pos, unsigned int len)
 286 {
 287         unsigned int pglen = nfs_page_length(page);
 288         unsigned int offset = pos & (PAGE_SIZE - 1);
 289         unsigned int end = offset + len;
 290 
 291         return !pglen || (end >= pglen && !offset);
 292 }
 293 
 294 static bool nfs_want_read_modify_write(struct file *file, struct page *page,
 295                         loff_t pos, unsigned int len)
 296 {
 297         /*
 298          * Up-to-date pages, those with ongoing or full-page write
 299          * don't need read/modify/write
 300          */
 301         if (PageUptodate(page) || PagePrivate(page) ||
 302             nfs_full_page_write(page, pos, len))
 303                 return false;
 304 
 305         if (pnfs_ld_read_whole_page(file->f_mapping->host))
 306                 return true;
 307         /* Open for reading too? */
 308         if (file->f_mode & FMODE_READ)
 309                 return true;
 310         return false;
 311 }
 312 
 313 /*
 314  * This does the "real" work of the write. We must allocate and lock the
 315  * page to be sent back to the generic routine, which then copies the
 316  * data from user space.
 317  *
 318  * If the writer ends up delaying the write, the writer needs to
 319  * increment the page use counts until he is done with the page.
 320  */
 321 static int nfs_write_begin(struct file *file, struct address_space *mapping,
 322                         loff_t pos, unsigned len, unsigned flags,
 323                         struct page **pagep, void **fsdata)
 324 {
 325         int ret;
 326         pgoff_t index = pos >> PAGE_SHIFT;
 327         struct page *page;
 328         int once_thru = 0;
 329 
 330         dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)\n",
 331                 file, mapping->host->i_ino, len, (long long) pos);
 332 
 333 start:
 334         page = grab_cache_page_write_begin(mapping, index, flags);
 335         if (!page)
 336                 return -ENOMEM;
 337         *pagep = page;
 338 
 339         ret = nfs_flush_incompatible(file, page);
 340         if (ret) {
 341                 unlock_page(page);
 342                 put_page(page);
 343         } else if (!once_thru &&
 344                    nfs_want_read_modify_write(file, page, pos, len)) {
 345                 once_thru = 1;
 346                 ret = nfs_readpage(file, page);
 347                 put_page(page);
 348                 if (!ret)
 349                         goto start;
 350         }
 351         return ret;
 352 }
 353 
 354 static int nfs_write_end(struct file *file, struct address_space *mapping,
 355                         loff_t pos, unsigned len, unsigned copied,
 356                         struct page *page, void *fsdata)
 357 {
 358         unsigned offset = pos & (PAGE_SIZE - 1);
 359         struct nfs_open_context *ctx = nfs_file_open_context(file);
 360         int status;
 361 
 362         dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)\n",
 363                 file, mapping->host->i_ino, len, (long long) pos);
 364 
 365         /*
 366          * Zero any uninitialised parts of the page, and then mark the page
 367          * as up to date if it turns out that we're extending the file.
 368          */
 369         if (!PageUptodate(page)) {
 370                 unsigned pglen = nfs_page_length(page);
 371                 unsigned end = offset + copied;
 372 
 373                 if (pglen == 0) {
 374                         zero_user_segments(page, 0, offset,
 375                                         end, PAGE_SIZE);
 376                         SetPageUptodate(page);
 377                 } else if (end >= pglen) {
 378                         zero_user_segment(page, end, PAGE_SIZE);
 379                         if (offset == 0)
 380                                 SetPageUptodate(page);
 381                 } else
 382                         zero_user_segment(page, pglen, PAGE_SIZE);
 383         }
 384 
 385         status = nfs_updatepage(file, page, offset, copied);
 386 
 387         unlock_page(page);
 388         put_page(page);
 389 
 390         if (status < 0)
 391                 return status;
 392         NFS_I(mapping->host)->write_io += copied;
 393 
 394         if (nfs_ctx_key_to_expire(ctx, mapping->host)) {
 395                 status = nfs_wb_all(mapping->host);
 396                 if (status < 0)
 397                         return status;
 398         }
 399 
 400         return copied;
 401 }
 402 
 403 /*
 404  * Partially or wholly invalidate a page
 405  * - Release the private state associated with a page if undergoing complete
 406  *   page invalidation
 407  * - Called if either PG_private or PG_fscache is set on the page
 408  * - Caller holds page lock
 409  */
 410 static void nfs_invalidate_page(struct page *page, unsigned int offset,
 411                                 unsigned int length)
 412 {
 413         dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)\n",
 414                  page, offset, length);
 415 
 416         if (offset != 0 || length < PAGE_SIZE)
 417                 return;
 418         /* Cancel any unstarted writes on this page */
 419         nfs_wb_page_cancel(page_file_mapping(page)->host, page);
 420 
 421         nfs_fscache_invalidate_page(page, page->mapping->host);
 422 }
 423 
 424 /*
 425  * Attempt to release the private state associated with a page
 426  * - Called if either PG_private or PG_fscache is set on the page
 427  * - Caller holds page lock
 428  * - Return true (may release page) or false (may not)
 429  */
 430 static int nfs_release_page(struct page *page, gfp_t gfp)
 431 {
 432         dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
 433 
 434         /* If PagePrivate() is set, then the page is not freeable */
 435         if (PagePrivate(page))
 436                 return 0;
 437         return nfs_fscache_release_page(page, gfp);
 438 }
 439 
 440 static void nfs_check_dirty_writeback(struct page *page,
 441                                 bool *dirty, bool *writeback)
 442 {
 443         struct nfs_inode *nfsi;
 444         struct address_space *mapping = page_file_mapping(page);
 445 
 446         if (!mapping || PageSwapCache(page))
 447                 return;
 448 
 449         /*
 450          * Check if an unstable page is currently being committed and
 451          * if so, have the VM treat it as if the page is under writeback
 452          * so it will not block due to pages that will shortly be freeable.
 453          */
 454         nfsi = NFS_I(mapping->host);
 455         if (atomic_read(&nfsi->commit_info.rpcs_out)) {
 456                 *writeback = true;
 457                 return;
 458         }
 459 
 460         /*
 461          * If PagePrivate() is set, then the page is not freeable and as the
 462          * inode is not being committed, it's not going to be cleaned in the
 463          * near future so treat it as dirty
 464          */
 465         if (PagePrivate(page))
 466                 *dirty = true;
 467 }
 468 
 469 /*
 470  * Attempt to clear the private state associated with a page when an error
 471  * occurs that requires the cached contents of an inode to be written back or
 472  * destroyed
 473  * - Called if either PG_private or fscache is set on the page
 474  * - Caller holds page lock
 475  * - Return 0 if successful, -error otherwise
 476  */
 477 static int nfs_launder_page(struct page *page)
 478 {
 479         struct inode *inode = page_file_mapping(page)->host;
 480         struct nfs_inode *nfsi = NFS_I(inode);
 481 
 482         dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
 483                 inode->i_ino, (long long)page_offset(page));
 484 
 485         nfs_fscache_wait_on_page_write(nfsi, page);
 486         return nfs_wb_page(inode, page);
 487 }
 488 
 489 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
 490                                                 sector_t *span)
 491 {
 492         struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
 493 
 494         *span = sis->pages;
 495 
 496         return rpc_clnt_swap_activate(clnt);
 497 }
 498 
 499 static void nfs_swap_deactivate(struct file *file)
 500 {
 501         struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
 502 
 503         rpc_clnt_swap_deactivate(clnt);
 504 }
 505 
 506 const struct address_space_operations nfs_file_aops = {
 507         .readpage = nfs_readpage,
 508         .readpages = nfs_readpages,
 509         .set_page_dirty = __set_page_dirty_nobuffers,
 510         .writepage = nfs_writepage,
 511         .writepages = nfs_writepages,
 512         .write_begin = nfs_write_begin,
 513         .write_end = nfs_write_end,
 514         .invalidatepage = nfs_invalidate_page,
 515         .releasepage = nfs_release_page,
 516         .direct_IO = nfs_direct_IO,
 517 #ifdef CONFIG_MIGRATION
 518         .migratepage = nfs_migrate_page,
 519 #endif
 520         .launder_page = nfs_launder_page,
 521         .is_dirty_writeback = nfs_check_dirty_writeback,
 522         .error_remove_page = generic_error_remove_page,
 523         .swap_activate = nfs_swap_activate,
 524         .swap_deactivate = nfs_swap_deactivate,
 525 };
 526 
 527 /*
 528  * Notification that a PTE pointing to an NFS page is about to be made
 529  * writable, implying that someone is about to modify the page through a
 530  * shared-writable mapping
 531  */
 532 static vm_fault_t nfs_vm_page_mkwrite(struct vm_fault *vmf)
 533 {
 534         struct page *page = vmf->page;
 535         struct file *filp = vmf->vma->vm_file;
 536         struct inode *inode = file_inode(filp);
 537         unsigned pagelen;
 538         vm_fault_t ret = VM_FAULT_NOPAGE;
 539         struct address_space *mapping;
 540 
 541         dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n",
 542                 filp, filp->f_mapping->host->i_ino,
 543                 (long long)page_offset(page));
 544 
 545         sb_start_pagefault(inode->i_sb);
 546 
 547         /* make sure the cache has finished storing the page */
 548         nfs_fscache_wait_on_page_write(NFS_I(inode), page);
 549 
 550         wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
 551                         nfs_wait_bit_killable, TASK_KILLABLE);
 552 
 553         lock_page(page);
 554         mapping = page_file_mapping(page);
 555         if (mapping != inode->i_mapping)
 556                 goto out_unlock;
 557 
 558         wait_on_page_writeback(page);
 559 
 560         pagelen = nfs_page_length(page);
 561         if (pagelen == 0)
 562                 goto out_unlock;
 563 
 564         ret = VM_FAULT_LOCKED;
 565         if (nfs_flush_incompatible(filp, page) == 0 &&
 566             nfs_updatepage(filp, page, 0, pagelen) == 0)
 567                 goto out;
 568 
 569         ret = VM_FAULT_SIGBUS;
 570 out_unlock:
 571         unlock_page(page);
 572 out:
 573         sb_end_pagefault(inode->i_sb);
 574         return ret;
 575 }
 576 
 577 static const struct vm_operations_struct nfs_file_vm_ops = {
 578         .fault = filemap_fault,
 579         .map_pages = filemap_map_pages,
 580         .page_mkwrite = nfs_vm_page_mkwrite,
 581 };
 582 
 583 static int nfs_need_check_write(struct file *filp, struct inode *inode)
 584 {
 585         struct nfs_open_context *ctx;
 586 
 587         ctx = nfs_file_open_context(filp);
 588         if (nfs_ctx_key_to_expire(ctx, inode))
 589                 return 1;
 590         return 0;
 591 }
 592 
 593 ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
 594 {
 595         struct file *file = iocb->ki_filp;
 596         struct inode *inode = file_inode(file);
 597         unsigned long written = 0;
 598         ssize_t result;
 599 
 600         result = nfs_key_timeout_notify(file, inode);
 601         if (result)
 602                 return result;
 603 
 604         if (iocb->ki_flags & IOCB_DIRECT)
 605                 return nfs_file_direct_write(iocb, from);
 606 
 607         dprintk("NFS: write(%pD2, %zu@%Ld)\n",
 608                 file, iov_iter_count(from), (long long) iocb->ki_pos);
 609 
 610         if (IS_SWAPFILE(inode))
 611                 goto out_swapfile;
 612         /*
 613          * O_APPEND implies that we must revalidate the file length.
 614          */
 615         if (iocb->ki_flags & IOCB_APPEND) {
 616                 result = nfs_revalidate_file_size(inode, file);
 617                 if (result)
 618                         goto out;
 619         }
 620         if (iocb->ki_pos > i_size_read(inode))
 621                 nfs_revalidate_mapping(inode, file->f_mapping);
 622 
 623         nfs_start_io_write(inode);
 624         result = generic_write_checks(iocb, from);
 625         if (result > 0) {
 626                 current->backing_dev_info = inode_to_bdi(inode);
 627                 result = generic_perform_write(file, from, iocb->ki_pos);
 628                 current->backing_dev_info = NULL;
 629         }
 630         nfs_end_io_write(inode);
 631         if (result <= 0)
 632                 goto out;
 633 
 634         written = result;
 635         iocb->ki_pos += written;
 636         result = generic_write_sync(iocb, written);
 637         if (result < 0)
 638                 goto out;
 639 
 640         /* Return error values */
 641         if (nfs_need_check_write(file, inode)) {
 642                 int err = nfs_wb_all(inode);
 643                 if (err < 0)
 644                         result = err;
 645         }
 646         nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
 647 out:
 648         return result;
 649 
 650 out_swapfile:
 651         printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
 652         return -EBUSY;
 653 }
 654 EXPORT_SYMBOL_GPL(nfs_file_write);
 655 
 656 static int
 657 do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
 658 {
 659         struct inode *inode = filp->f_mapping->host;
 660         int status = 0;
 661         unsigned int saved_type = fl->fl_type;
 662 
 663         /* Try local locking first */
 664         posix_test_lock(filp, fl);
 665         if (fl->fl_type != F_UNLCK) {
 666                 /* found a conflict */
 667                 goto out;
 668         }
 669         fl->fl_type = saved_type;
 670 
 671         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
 672                 goto out_noconflict;
 673 
 674         if (is_local)
 675                 goto out_noconflict;
 676 
 677         status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 678 out:
 679         return status;
 680 out_noconflict:
 681         fl->fl_type = F_UNLCK;
 682         goto out;
 683 }
 684 
 685 static int
 686 do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
 687 {
 688         struct inode *inode = filp->f_mapping->host;
 689         struct nfs_lock_context *l_ctx;
 690         int status;
 691 
 692         /*
 693          * Flush all pending writes before doing anything
 694          * with locks..
 695          */
 696         nfs_wb_all(inode);
 697 
 698         l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
 699         if (!IS_ERR(l_ctx)) {
 700                 status = nfs_iocounter_wait(l_ctx);
 701                 nfs_put_lock_context(l_ctx);
 702                 /*  NOTE: special case
 703                  *      If we're signalled while cleaning up locks on process exit, we
 704                  *      still need to complete the unlock.
 705                  */
 706                 if (status < 0 && !(fl->fl_flags & FL_CLOSE))
 707                         return status;
 708         }
 709 
 710         /*
 711          * Use local locking if mounted with "-onolock" or with appropriate
 712          * "-olocal_lock="
 713          */
 714         if (!is_local)
 715                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 716         else
 717                 status = locks_lock_file_wait(filp, fl);
 718         return status;
 719 }
 720 
 721 static int
 722 do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
 723 {
 724         struct inode *inode = filp->f_mapping->host;
 725         int status;
 726 
 727         /*
 728          * Flush all pending writes before doing anything
 729          * with locks..
 730          */
 731         status = nfs_sync_mapping(filp->f_mapping);
 732         if (status != 0)
 733                 goto out;
 734 
 735         /*
 736          * Use local locking if mounted with "-onolock" or with appropriate
 737          * "-olocal_lock="
 738          */
 739         if (!is_local)
 740                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 741         else
 742                 status = locks_lock_file_wait(filp, fl);
 743         if (status < 0)
 744                 goto out;
 745 
 746         /*
 747          * Invalidate cache to prevent missing any changes.  If
 748          * the file is mapped, clear the page cache as well so
 749          * those mappings will be loaded.
 750          *
 751          * This makes locking act as a cache coherency point.
 752          */
 753         nfs_sync_mapping(filp->f_mapping);
 754         if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {
 755                 nfs_zap_caches(inode);
 756                 if (mapping_mapped(filp->f_mapping))
 757                         nfs_revalidate_mapping(inode, filp->f_mapping);
 758         }
 759 out:
 760         return status;
 761 }
 762 
 763 /*
 764  * Lock a (portion of) a file
 765  */
 766 int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
 767 {
 768         struct inode *inode = filp->f_mapping->host;
 769         int ret = -ENOLCK;
 770         int is_local = 0;
 771 
 772         dprintk("NFS: lock(%pD2, t=%x, fl=%x, r=%lld:%lld)\n",
 773                         filp, fl->fl_type, fl->fl_flags,
 774                         (long long)fl->fl_start, (long long)fl->fl_end);
 775 
 776         nfs_inc_stats(inode, NFSIOS_VFSLOCK);
 777 
 778         /* No mandatory locks over NFS */
 779         if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
 780                 goto out_err;
 781 
 782         if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
 783                 is_local = 1;
 784 
 785         if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
 786                 ret = NFS_PROTO(inode)->lock_check_bounds(fl);
 787                 if (ret < 0)
 788                         goto out_err;
 789         }
 790 
 791         if (IS_GETLK(cmd))
 792                 ret = do_getlk(filp, cmd, fl, is_local);
 793         else if (fl->fl_type == F_UNLCK)
 794                 ret = do_unlk(filp, cmd, fl, is_local);
 795         else
 796                 ret = do_setlk(filp, cmd, fl, is_local);
 797 out_err:
 798         return ret;
 799 }
 800 EXPORT_SYMBOL_GPL(nfs_lock);
 801 
 802 /*
 803  * Lock a (portion of) a file
 804  */
 805 int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
 806 {
 807         struct inode *inode = filp->f_mapping->host;
 808         int is_local = 0;
 809 
 810         dprintk("NFS: flock(%pD2, t=%x, fl=%x)\n",
 811                         filp, fl->fl_type, fl->fl_flags);
 812 
 813         if (!(fl->fl_flags & FL_FLOCK))
 814                 return -ENOLCK;
 815 
 816         /*
 817          * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
 818          * any standard. In principle we might be able to support LOCK_MAND
 819          * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
 820          * NFS code is not set up for it.
 821          */
 822         if (fl->fl_type & LOCK_MAND)
 823                 return -EINVAL;
 824 
 825         if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
 826                 is_local = 1;
 827 
 828         /* We're simulating flock() locks using posix locks on the server */
 829         if (fl->fl_type == F_UNLCK)
 830                 return do_unlk(filp, cmd, fl, is_local);
 831         return do_setlk(filp, cmd, fl, is_local);
 832 }
 833 EXPORT_SYMBOL_GPL(nfs_flock);
 834 
 835 const struct file_operations nfs_file_operations = {
 836         .llseek         = nfs_file_llseek,
 837         .read_iter      = nfs_file_read,
 838         .write_iter     = nfs_file_write,
 839         .mmap           = nfs_file_mmap,
 840         .open           = nfs_file_open,
 841         .flush          = nfs_file_flush,
 842         .release        = nfs_file_release,
 843         .fsync          = nfs_file_fsync,
 844         .lock           = nfs_lock,
 845         .flock          = nfs_flock,
 846         .splice_read    = generic_file_splice_read,
 847         .splice_write   = iter_file_splice_write,
 848         .check_flags    = nfs_check_flags,
 849         .setlease       = simple_nosetlease,
 850 };
 851 EXPORT_SYMBOL_GPL(nfs_file_operations);