fs/nfs/file.c

   1 /*
   2  *  linux/fs/nfs/file.c
   3  *
   4  *  Copyright (C) 1992  Rick Sladkey
   5  *
   6  *  Changes Copyright (C) 1994 by Florian La Roche
   7  *   - Do not copy data too often around in the kernel.
   8  *   - In nfs_file_read the return value of kmalloc wasn't checked.
   9  *   - Put in a better version of read look-ahead buffering. Original idea
  10  *     and implementation by Wai S Kok elekokws@ee.nus.sg.
  11  *
  12  *  Expire cache on write to a file by Wai S Kok (Oct 1994).
  13  *
  14  *  Total rewrite of read side for new NFS buffer cache.. Linus.
  15  *
  16  *  nfs regular file handling functions
  17  */
  18
  19 #include <linux/time.h>
  20 #include <linux/kernel.h>
  21 #include <linux/errno.h>
  22 #include <linux/fcntl.h>
  23 #include <linux/stat.h>
  24 #include <linux/nfs_fs.h>
  25 #include <linux/nfs_mount.h>
  26 #include <linux/mm.h>
  27 #include <linux/slab.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/smp_lock.h>
  30 #include <linux/aio.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/system.h>
  34
  35 #include "delegation.h"
  36 #include "internal.h"
  37 #include "iostat.h"
  38
  39 #define NFSDBG_FACILITY         NFSDBG_FILE
  40
  41 static int nfs_file_open(struct inode *, struct file *);
  42 static int nfs_file_release(struct inode *, struct file *);
  43 static loff_t nfs_file_llseek(struct file *file, loff_t offset, int origin);
  44 static int  nfs_file_mmap(struct file *, struct vm_area_struct *);
  45 static ssize_t nfs_file_splice_read(struct file *filp, loff_t *ppos,
  46                                         struct pipe_inode_info *pipe,
  47                                         size_t count, unsigned int flags);
  48 static ssize_t nfs_file_read(struct kiocb *, const struct iovec *iov,
  49                                 unsigned long nr_segs, loff_t pos);
  50 static ssize_t nfs_file_write(struct kiocb *, const struct iovec *iov,
  51                                 unsigned long nr_segs, loff_t pos);
  52 static int  nfs_file_flush(struct file *, fl_owner_t id);
  53 static int  nfs_fsync(struct file *, struct dentry *dentry, int datasync);
  54 static int nfs_check_flags(int flags);
  55 static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl);
  56 static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl);
  57 static int nfs_setlease(struct file *file, long arg, struct file_lock **fl);
  58
  59 static struct vm_operations_struct nfs_file_vm_ops;
  60
  61 const struct file_operations nfs_file_operations = {
  62         .llseek         = nfs_file_llseek,
  63         .read           = do_sync_read,
  64         .write          = do_sync_write,
  65         .aio_read       = nfs_file_read,
  66         .aio_write      = nfs_file_write,
  67 #ifdef CONFIG_MMU
  68         .mmap           = nfs_file_mmap,
  69 #else
  70         .mmap           = generic_file_mmap,
  71 #endif
  72         .open           = nfs_file_open,
  73         .flush          = nfs_file_flush,
  74         .release        = nfs_file_release,
  75         .fsync          = nfs_fsync,
  76         .lock           = nfs_lock,
  77         .flock          = nfs_flock,
  78         .splice_read    = nfs_file_splice_read,
  79         .check_flags    = nfs_check_flags,
  80         .setlease       = nfs_setlease,
  81 };
  82
  83 const struct inode_operations nfs_file_inode_operations = {
  84         .permission     = nfs_permission,
  85         .getattr        = nfs_getattr,
  86         .setattr        = nfs_setattr,
  87 };
  88
  89 #ifdef CONFIG_NFS_V3
  90 const struct inode_operations nfs3_file_inode_operations = {
  91         .permission     = nfs_permission,
  92         .getattr        = nfs_getattr,
  93         .setattr        = nfs_setattr,
  94         .listxattr      = nfs3_listxattr,
  95         .getxattr       = nfs3_getxattr,
  96         .setxattr       = nfs3_setxattr,
  97         .removexattr    = nfs3_removexattr,
  98 };
  99 #endif  /* CONFIG_NFS_v3 */
 100
 101 /* Hack for future NFS swap support */
 102 #ifndef IS_SWAPFILE
 103 # define IS_SWAPFILE(inode)     (0)
 104 #endif
 105
 106 static int nfs_check_flags(int flags)
 107 {
 108         if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
 109                 return -EINVAL;
 110
 111         return 0;
 112 }
 113
 114 /*
 115  * Open file
 116  */
 117 static int
 118 nfs_file_open(struct inode *inode, struct file *filp)
 119 {
 120         int res;
 121
 122         res = nfs_check_flags(filp->f_flags);
 123         if (res)
 124                 return res;
 125
 126         nfs_inc_stats(inode, NFSIOS_VFSOPEN);
 127         lock_kernel();
 128         res = NFS_PROTO(inode)->file_open(inode, filp);
 129         unlock_kernel();
 130         return res;
 131 }
 132
 133 static int
 134 nfs_file_release(struct inode *inode, struct file *filp)
 135 {
 136         /* Ensure that dirty pages are flushed out with the right creds */
 137         if (filp->f_mode & FMODE_WRITE)
 138                 nfs_wb_all(filp->f_path.dentry->d_inode);
 139         nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
 140         return NFS_PROTO(inode)->file_release(inode, filp);
 141 }
 142
 143 /**
 144  * nfs_revalidate_size - Revalidate the file size
 145  * @inode - pointer to inode struct
 146  * @file - pointer to struct file
 147  *
 148  * Revalidates the file length. This is basically a wrapper around
 149  * nfs_revalidate_inode() that takes into account the fact that we may
 150  * have cached writes (in which case we don't care about the server's
 151  * idea of what the file length is), or O_DIRECT (in which case we
 152  * shouldn't trust the cache).
 153  */
 154 static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
 155 {
 156         struct nfs_server *server = NFS_SERVER(inode);
 157         struct nfs_inode *nfsi = NFS_I(inode);
 158
 159         if (server->flags & NFS_MOUNT_NOAC)
 160                 goto force_reval;
 161         if (filp->f_flags & O_DIRECT)
 162                 goto force_reval;
 163         if (nfsi->npages != 0)
 164                 return 0;
 165         if (!(nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE) && !nfs_attribute_timeout(inode))
 166                 return 0;
 167 force_reval:
 168         return __nfs_revalidate_inode(server, inode);
 169 }
 170
 171 static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
 172 {
 173         /* origin == SEEK_END => we must revalidate the cached file length */
 174         if (origin == SEEK_END) {
 175                 struct inode *inode = filp->f_mapping->host;
 176                 int retval = nfs_revalidate_file_size(inode, filp);
 177                 if (retval < 0)
 178                         return (loff_t)retval;
 179         }
 180         return remote_llseek(filp, offset, origin);
 181 }
 182
 183 /*
 184  * Helper for nfs_file_flush() and nfs_fsync()
 185  *
 186  * Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
 187  * disk, but it retrieves and clears ctx->error after synching, despite
 188  * the two being set at the same time in nfs_context_set_write_error().
 189  * This is because the former is used to notify the _next_ call to
 190  * nfs_file_write() that a write error occured, and hence cause it to
 191  * fall back to doing a synchronous write.
 192  */
 193 static int nfs_do_fsync(struct nfs_open_context *ctx, struct inode *inode)
 194 {
 195         int have_error, status;
 196         int ret = 0;
 197
 198         have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 199         status = nfs_wb_all(inode);
 200         have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 201         if (have_error)
 202                 ret = xchg(&ctx->error, 0);
 203         if (!ret)
 204                 ret = status;
 205         return ret;
 206 }
 207
 208 /*
 209  * Flush all dirty pages, and check for write errors.
 210  *
 211  */
 212 static int
 213 nfs_file_flush(struct file *file, fl_owner_t id)
 214 {
 215         struct nfs_open_context *ctx = nfs_file_open_context(file);
 216         struct inode    *inode = file->f_path.dentry->d_inode;
 217         int             status;
 218
 219         dfprintk(VFS, "nfs: flush(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
 220
 221         if ((file->f_mode & FMODE_WRITE) == 0)
 222                 return 0;
 223         nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
 224
 225         /* Ensure that data+attribute caches are up to date after close() */
 226         status = nfs_do_fsync(ctx, inode);
 227         if (!status)
 228                 nfs_revalidate_inode(NFS_SERVER(inode), inode);
 229         return status;
 230 }
 231
 232 static ssize_t
 233 nfs_file_read(struct kiocb *iocb, const struct iovec *iov,
 234                 unsigned long nr_segs, loff_t pos)
 235 {
 236         struct dentry * dentry = iocb->ki_filp->f_path.dentry;
 237         struct inode * inode = dentry->d_inode;
 238         ssize_t result;
 239         size_t count = iov_length(iov, nr_segs);
 240
 241         if (iocb->ki_filp->f_flags & O_DIRECT)
 242                 return nfs_file_direct_read(iocb, iov, nr_segs, pos);
 243
 244         dfprintk(VFS, "nfs: read(%s/%s, %lu@%lu)\n",
 245                 dentry->d_parent->d_name.name, dentry->d_name.name,
 246                 (unsigned long) count, (unsigned long) pos);
 247
 248         result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
 249         nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, count);
 250         if (!result)
 251                 result = generic_file_aio_read(iocb, iov, nr_segs, pos);
 252         return result;
 253 }
 254
 255 static ssize_t
 256 nfs_file_splice_read(struct file *filp, loff_t *ppos,
 257                      struct pipe_inode_info *pipe, size_t count,
 258                      unsigned int flags)
 259 {
 260         struct dentry *dentry = filp->f_path.dentry;
 261         struct inode *inode = dentry->d_inode;
 262         ssize_t res;
 263
 264         dfprintk(VFS, "nfs: splice_read(%s/%s, %lu@%Lu)\n",
 265                 dentry->d_parent->d_name.name, dentry->d_name.name,
 266                 (unsigned long) count, (unsigned long long) *ppos);
 267
 268         res = nfs_revalidate_mapping(inode, filp->f_mapping);
 269         if (!res)
 270                 res = generic_file_splice_read(filp, ppos, pipe, count, flags);
 271         return res;
 272 }
 273
 274 static int
 275 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
 276 {
 277         struct dentry *dentry = file->f_path.dentry;
 278         struct inode *inode = dentry->d_inode;
 279         int     status;
 280
 281         dfprintk(VFS, "nfs: mmap(%s/%s)\n",
 282                 dentry->d_parent->d_name.name, dentry->d_name.name);
 283
 284         status = nfs_revalidate_mapping(inode, file->f_mapping);
 285         if (!status) {
 286                 vma->vm_ops = &nfs_file_vm_ops;
 287                 vma->vm_flags |= VM_CAN_NONLINEAR;
 288                 file_accessed(file);
 289         }
 290         return status;
 291 }
 292
 293 /*
 294  * Flush any dirty pages for this process, and check for write errors.
 295  * The return status from this call provides a reliable indication of
 296  * whether any write errors occurred for this process.
 297  */
 298 static int
 299 nfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 300 {
 301         struct nfs_open_context *ctx = nfs_file_open_context(file);
 302         struct inode *inode = dentry->d_inode;
 303
 304         dfprintk(VFS, "nfs: fsync(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
 305
 306         nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
 307         return nfs_do_fsync(ctx, inode);
 308 }
 309
 310 /*
 311  * This does the "real" work of the write. We must allocate and lock the
 312  * page to be sent back to the generic routine, which then copies the
 313  * data from user space.
 314  *
 315  * If the writer ends up delaying the write, the writer needs to
 316  * increment the page use counts until he is done with the page.
 317  */
 318 static int nfs_write_begin(struct file *file, struct address_space *mapping,
 319                         loff_t pos, unsigned len, unsigned flags,
 320                         struct page **pagep, void **fsdata)
 321 {
 322         int ret;
 323         pgoff_t index;
 324         struct page *page;
 325         index = pos >> PAGE_CACHE_SHIFT;
 326
 327         page = __grab_cache_page(mapping, index);
 328         if (!page)
 329                 return -ENOMEM;
 330         *pagep = page;
 331
 332         ret = nfs_flush_incompatible(file, page);
 333         if (ret) {
 334                 unlock_page(page);
 335                 page_cache_release(page);
 336         }
 337         return ret;
 338 }
 339
 340 static int nfs_write_end(struct file *file, struct address_space *mapping,
 341                         loff_t pos, unsigned len, unsigned copied,
 342                         struct page *page, void *fsdata)
 343 {
 344         unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
 345         int status;
 346
 347         lock_kernel();
 348         status = nfs_updatepage(file, page, offset, copied);
 349         unlock_kernel();
 350
 351         unlock_page(page);
 352         page_cache_release(page);
 353
 354         if (status < 0)
 355                 return status;
 356         return copied;
 357 }
 358
 359 static void nfs_invalidate_page(struct page *page, unsigned long offset)
 360 {
 361         if (offset != 0)
 362                 return;
 363         /* Cancel any unstarted writes on this page */
 364         nfs_wb_page_cancel(page->mapping->host, page);
 365 }
 366
 367 static int nfs_release_page(struct page *page, gfp_t gfp)
 368 {
 369         /* If PagePrivate() is set, then the page is not freeable */
 370         return 0;
 371 }
 372
 373 static int nfs_launder_page(struct page *page)
 374 {
 375         return nfs_wb_page(page->mapping->host, page);
 376 }
 377
 378 const struct address_space_operations nfs_file_aops = {
 379         .readpage = nfs_readpage,
 380         .readpages = nfs_readpages,
 381         .set_page_dirty = __set_page_dirty_nobuffers,
 382         .writepage = nfs_writepage,
 383         .writepages = nfs_writepages,
 384         .write_begin = nfs_write_begin,
 385         .write_end = nfs_write_end,
 386         .invalidatepage = nfs_invalidate_page,
 387         .releasepage = nfs_release_page,
 388         .direct_IO = nfs_direct_IO,
 389         .launder_page = nfs_launder_page,
 390 };
 391
 392 static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
 393 {
 394         struct file *filp = vma->vm_file;
 395         unsigned pagelen;
 396         int ret = -EINVAL;
 397         struct address_space *mapping;
 398
 399         lock_page(page);
 400         mapping = page->mapping;
 401         if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping)
 402                 goto out_unlock;
 403
 404         ret = 0;
 405         pagelen = nfs_page_length(page);
 406         if (pagelen == 0)
 407                 goto out_unlock;
 408
 409         ret = nfs_flush_incompatible(filp, page);
 410         if (ret != 0)
 411                 goto out_unlock;
 412
 413         ret = nfs_updatepage(filp, page, 0, pagelen);
 414         if (ret == 0)
 415                 ret = pagelen;
 416 out_unlock:
 417         unlock_page(page);
 418         return ret;
 419 }
 420
 421 static struct vm_operations_struct nfs_file_vm_ops = {
 422         .fault = filemap_fault,
 423         .page_mkwrite = nfs_vm_page_mkwrite,
 424 };
 425
 426 static int nfs_need_sync_write(struct file *filp, struct inode *inode)
 427 {
 428         struct nfs_open_context *ctx;
 429
 430         if (IS_SYNC(inode) || (filp->f_flags & O_SYNC))
 431                 return 1;
 432         ctx = nfs_file_open_context(filp);
 433         if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags))
 434                 return 1;
 435         return 0;
 436 }
 437
 438 static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
 439                                 unsigned long nr_segs, loff_t pos)
 440 {
 441         struct dentry * dentry = iocb->ki_filp->f_path.dentry;
 442         struct inode * inode = dentry->d_inode;
 443         ssize_t result;
 444         size_t count = iov_length(iov, nr_segs);
 445
 446         if (iocb->ki_filp->f_flags & O_DIRECT)
 447                 return nfs_file_direct_write(iocb, iov, nr_segs, pos);
 448
 449         dfprintk(VFS, "nfs: write(%s/%s(%ld), %lu@%Ld)\n",
 450                 dentry->d_parent->d_name.name, dentry->d_name.name,
 451                 inode->i_ino, (unsigned long) count, (long long) pos);
 452
 453         result = -EBUSY;
 454         if (IS_SWAPFILE(inode))
 455                 goto out_swapfile;
 456         /*
 457          * O_APPEND implies that we must revalidate the file length.
 458          */
 459         if (iocb->ki_filp->f_flags & O_APPEND) {
 460                 result = nfs_revalidate_file_size(inode, iocb->ki_filp);
 461                 if (result)
 462                         goto out;
 463         }
 464
 465         result = count;
 466         if (!count)
 467                 goto out;
 468
 469         nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, count);
 470         result = generic_file_aio_write(iocb, iov, nr_segs, pos);
 471         /* Return error values for O_SYNC and IS_SYNC() */
 472         if (result >= 0 && nfs_need_sync_write(iocb->ki_filp, inode)) {
 473                 int err = nfs_do_fsync(nfs_file_open_context(iocb->ki_filp), inode);
 474                 if (err < 0)
 475                         result = err;
 476         }
 477 out:
 478         return result;
 479
 480 out_swapfile:
 481         printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
 482         goto out;
 483 }
 484
 485 static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
 486 {
 487         struct inode *inode = filp->f_mapping->host;
 488         int status = 0;
 489
 490         lock_kernel();
 491         /* Try local locking first */
 492         posix_test_lock(filp, fl);
 493         if (fl->fl_type != F_UNLCK) {
 494                 /* found a conflict */
 495                 goto out;
 496         }
 497
 498         if (nfs_have_delegation(inode, FMODE_READ))
 499                 goto out_noconflict;
 500
 501         if (NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)
 502                 goto out_noconflict;
 503
 504         status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 505 out:
 506         unlock_kernel();
 507         return status;
 508 out_noconflict:
 509         fl->fl_type = F_UNLCK;
 510         goto out;
 511 }
 512
 513 static int do_vfs_lock(struct file *file, struct file_lock *fl)
 514 {
 515         int res = 0;
 516         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 517                 case FL_POSIX:
 518                         res = posix_lock_file_wait(file, fl);
 519                         break;
 520                 case FL_FLOCK:
 521                         res = flock_lock_file_wait(file, fl);
 522                         break;
 523                 default:
 524                         BUG();
 525         }
 526         if (res < 0)
 527                 dprintk(KERN_WARNING "%s: VFS is out of sync with lock manager"
 528                         " - error %d!\n",
 529                                 __func__, res);
 530         return res;
 531 }
 532
 533 static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
 534 {
 535         struct inode *inode = filp->f_mapping->host;
 536         int status;
 537
 538         /*
 539          * Flush all pending writes before doing anything
 540          * with locks..
 541          */
 542         nfs_sync_mapping(filp->f_mapping);
 543
 544         /* NOTE: special case
 545          *      If we're signalled while cleaning up locks on process exit, we
 546          *      still need to complete the unlock.
 547          */
 548         lock_kernel();
 549         /* Use local locking if mounted with "-onolock" */
 550         if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM))
 551                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 552         else
 553                 status = do_vfs_lock(filp, fl);
 554         unlock_kernel();
 555         return status;
 556 }
 557
 558 static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
 559 {
 560         struct inode *inode = filp->f_mapping->host;
 561         int status;
 562
 563         /*
 564          * Flush all pending writes before doing anything
 565          * with locks..
 566          */
 567         status = nfs_sync_mapping(filp->f_mapping);
 568         if (status != 0)
 569                 goto out;
 570
 571         lock_kernel();
 572         /* Use local locking if mounted with "-onolock" */
 573         if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM))
 574                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 575         else
 576                 status = do_vfs_lock(filp, fl);
 577         unlock_kernel();
 578         if (status < 0)
 579                 goto out;
 580         /*
 581          * Make sure we clear the cache whenever we try to get the lock.
 582          * This makes locking act as a cache coherency point.
 583          */
 584         nfs_sync_mapping(filp->f_mapping);
 585         nfs_zap_caches(inode);
 586 out:
 587         return status;
 588 }
 589
 590 /*
 591  * Lock a (portion of) a file
 592  */
 593 static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
 594 {
 595         struct inode * inode = filp->f_mapping->host;
 596
 597         dprintk("NFS: nfs_lock(f=%s/%ld, t=%x, fl=%x, r=%Ld:%Ld)\n",
 598                         inode->i_sb->s_id, inode->i_ino,
 599                         fl->fl_type, fl->fl_flags,
 600                         (long long)fl->fl_start, (long long)fl->fl_end);
 601         nfs_inc_stats(inode, NFSIOS_VFSLOCK);
 602
 603         /* No mandatory locks over NFS */
 604         if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
 605                 return -ENOLCK;
 606
 607         if (IS_GETLK(cmd))
 608                 return do_getlk(filp, cmd, fl);
 609         if (fl->fl_type == F_UNLCK)
 610                 return do_unlk(filp, cmd, fl);
 611         return do_setlk(filp, cmd, fl);
 612 }
 613
 614 /*
 615  * Lock a (portion of) a file
 616  */
 617 static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
 618 {
 619         dprintk("NFS: nfs_flock(f=%s/%ld, t=%x, fl=%x)\n",
 620                         filp->f_path.dentry->d_inode->i_sb->s_id,
 621                         filp->f_path.dentry->d_inode->i_ino,
 622                         fl->fl_type, fl->fl_flags);
 623
 624         /*
 625          * No BSD flocks over NFS allowed.
 626          * Note: we could try to fake a POSIX lock request here by
 627          * using ((u32) filp | 0x80000000) or some such as the pid.
 628          * Not sure whether that would be unique, though, or whether
 629          * that would break in other places.
 630          */
 631         if (!(fl->fl_flags & FL_FLOCK))
 632                 return -ENOLCK;
 633
 634         /* We're simulating flock() locks using posix locks on the server */
 635         fl->fl_owner = (fl_owner_t)filp;
 636         fl->fl_start = 0;
 637         fl->fl_end = OFFSET_MAX;
 638
 639         if (fl->fl_type == F_UNLCK)
 640                 return do_unlk(filp, cmd, fl);
 641         return do_setlk(filp, cmd, fl);
 642 }
 643
 644 static int nfs_setlease(struct file *file, long arg, struct file_lock **fl)
 645 {
 646         /*
 647          * There is no protocol support for leases, so we have no way
 648          * to implement them correctly in the face of opens by other
 649          * clients.
 650          */
 651         return -EINVAL;
 652 }