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 #ifdef CONFIG_NFS_DIRECTIO
 242         if (iocb->ki_filp->f_flags & O_DIRECT)
 243                 return nfs_file_direct_read(iocb, iov, nr_segs, pos);
 244 #endif
 245
 246         dfprintk(VFS, "nfs: read(%s/%s, %lu@%lu)\n",
 247                 dentry->d_parent->d_name.name, dentry->d_name.name,
 248                 (unsigned long) count, (unsigned long) pos);
 249
 250         result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
 251         nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, count);
 252         if (!result)
 253                 result = generic_file_aio_read(iocb, iov, nr_segs, pos);
 254         return result;
 255 }
 256
 257 static ssize_t
 258 nfs_file_splice_read(struct file *filp, loff_t *ppos,
 259                      struct pipe_inode_info *pipe, size_t count,
 260                      unsigned int flags)
 261 {
 262         struct dentry *dentry = filp->f_path.dentry;
 263         struct inode *inode = dentry->d_inode;
 264         ssize_t res;
 265
 266         dfprintk(VFS, "nfs: splice_read(%s/%s, %lu@%Lu)\n",
 267                 dentry->d_parent->d_name.name, dentry->d_name.name,
 268                 (unsigned long) count, (unsigned long long) *ppos);
 269
 270         res = nfs_revalidate_mapping(inode, filp->f_mapping);
 271         if (!res)
 272                 res = generic_file_splice_read(filp, ppos, pipe, count, flags);
 273         return res;
 274 }
 275
 276 static int
 277 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
 278 {
 279         struct dentry *dentry = file->f_path.dentry;
 280         struct inode *inode = dentry->d_inode;
 281         int     status;
 282
 283         dfprintk(VFS, "nfs: mmap(%s/%s)\n",
 284                 dentry->d_parent->d_name.name, dentry->d_name.name);
 285
 286         status = nfs_revalidate_mapping(inode, file->f_mapping);
 287         if (!status) {
 288                 vma->vm_ops = &nfs_file_vm_ops;
 289                 vma->vm_flags |= VM_CAN_NONLINEAR;
 290                 file_accessed(file);
 291         }
 292         return status;
 293 }
 294
 295 /*
 296  * Flush any dirty pages for this process, and check for write errors.
 297  * The return status from this call provides a reliable indication of
 298  * whether any write errors occurred for this process.
 299  */
 300 static int
 301 nfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 302 {
 303         struct nfs_open_context *ctx = nfs_file_open_context(file);
 304         struct inode *inode = dentry->d_inode;
 305
 306         dfprintk(VFS, "nfs: fsync(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
 307
 308         nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
 309         return nfs_do_fsync(ctx, inode);
 310 }
 311
 312 /*
 313  * This does the "real" work of the write. We must allocate and lock the
 314  * page to be sent back to the generic routine, which then copies the
 315  * data from user space.
 316  *
 317  * If the writer ends up delaying the write, the writer needs to
 318  * increment the page use counts until he is done with the page.
 319  */
 320 static int nfs_write_begin(struct file *file, struct address_space *mapping,
 321                         loff_t pos, unsigned len, unsigned flags,
 322                         struct page **pagep, void **fsdata)
 323 {
 324         int ret;
 325         pgoff_t index;
 326         struct page *page;
 327         index = pos >> PAGE_CACHE_SHIFT;
 328
 329         page = __grab_cache_page(mapping, index);
 330         if (!page)
 331                 return -ENOMEM;
 332         *pagep = page;
 333
 334         ret = nfs_flush_incompatible(file, page);
 335         if (ret) {
 336                 unlock_page(page);
 337                 page_cache_release(page);
 338         }
 339         return ret;
 340 }
 341
 342 static int nfs_write_end(struct file *file, struct address_space *mapping,
 343                         loff_t pos, unsigned len, unsigned copied,
 344                         struct page *page, void *fsdata)
 345 {
 346         unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
 347         int status;
 348
 349         lock_kernel();
 350         status = nfs_updatepage(file, page, offset, copied);
 351         unlock_kernel();
 352
 353         unlock_page(page);
 354         page_cache_release(page);
 355
 356         if (status < 0)
 357                 return status;
 358         return copied;
 359 }
 360
 361 static void nfs_invalidate_page(struct page *page, unsigned long offset)
 362 {
 363         if (offset != 0)
 364                 return;
 365         /* Cancel any unstarted writes on this page */
 366         nfs_wb_page_cancel(page->mapping->host, page);
 367 }
 368
 369 static int nfs_release_page(struct page *page, gfp_t gfp)
 370 {
 371         /* If PagePrivate() is set, then the page is not freeable */
 372         return 0;
 373 }
 374
 375 static int nfs_launder_page(struct page *page)
 376 {
 377         return nfs_wb_page(page->mapping->host, page);
 378 }
 379
 380 const struct address_space_operations nfs_file_aops = {
 381         .readpage = nfs_readpage,
 382         .readpages = nfs_readpages,
 383         .set_page_dirty = __set_page_dirty_nobuffers,
 384         .writepage = nfs_writepage,
 385         .writepages = nfs_writepages,
 386         .write_begin = nfs_write_begin,
 387         .write_end = nfs_write_end,
 388         .invalidatepage = nfs_invalidate_page,
 389         .releasepage = nfs_release_page,
 390 #ifdef CONFIG_NFS_DIRECTIO
 391         .direct_IO = nfs_direct_IO,
 392 #endif
 393         .launder_page = nfs_launder_page,
 394 };
 395
 396 static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
 397 {
 398         struct file *filp = vma->vm_file;
 399         unsigned pagelen;
 400         int ret = -EINVAL;
 401         struct address_space *mapping;
 402
 403         lock_page(page);
 404         mapping = page->mapping;
 405         if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping)
 406                 goto out_unlock;
 407
 408         ret = 0;
 409         pagelen = nfs_page_length(page);
 410         if (pagelen == 0)
 411                 goto out_unlock;
 412
 413         ret = nfs_flush_incompatible(filp, page);
 414         if (ret != 0)
 415                 goto out_unlock;
 416
 417         ret = nfs_updatepage(filp, page, 0, pagelen);
 418         if (ret == 0)
 419                 ret = pagelen;
 420 out_unlock:
 421         unlock_page(page);
 422         return ret;
 423 }
 424
 425 static struct vm_operations_struct nfs_file_vm_ops = {
 426         .fault = filemap_fault,
 427         .page_mkwrite = nfs_vm_page_mkwrite,
 428 };
 429
 430 static int nfs_need_sync_write(struct file *filp, struct inode *inode)
 431 {
 432         struct nfs_open_context *ctx;
 433
 434         if (IS_SYNC(inode) || (filp->f_flags & O_SYNC))
 435                 return 1;
 436         ctx = nfs_file_open_context(filp);
 437         if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags))
 438                 return 1;
 439         return 0;
 440 }
 441
 442 static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
 443                                 unsigned long nr_segs, loff_t pos)
 444 {
 445         struct dentry * dentry = iocb->ki_filp->f_path.dentry;
 446         struct inode * inode = dentry->d_inode;
 447         ssize_t result;
 448         size_t count = iov_length(iov, nr_segs);
 449
 450 #ifdef CONFIG_NFS_DIRECTIO
 451         if (iocb->ki_filp->f_flags & O_DIRECT)
 452                 return nfs_file_direct_write(iocb, iov, nr_segs, pos);
 453 #endif
 454
 455         dfprintk(VFS, "nfs: write(%s/%s(%ld), %lu@%Ld)\n",
 456                 dentry->d_parent->d_name.name, dentry->d_name.name,
 457                 inode->i_ino, (unsigned long) count, (long long) pos);
 458
 459         result = -EBUSY;
 460         if (IS_SWAPFILE(inode))
 461                 goto out_swapfile;
 462         /*
 463          * O_APPEND implies that we must revalidate the file length.
 464          */
 465         if (iocb->ki_filp->f_flags & O_APPEND) {
 466                 result = nfs_revalidate_file_size(inode, iocb->ki_filp);
 467                 if (result)
 468                         goto out;
 469         }
 470
 471         result = count;
 472         if (!count)
 473                 goto out;
 474
 475         nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, count);
 476         result = generic_file_aio_write(iocb, iov, nr_segs, pos);
 477         /* Return error values for O_SYNC and IS_SYNC() */
 478         if (result >= 0 && nfs_need_sync_write(iocb->ki_filp, inode)) {
 479                 int err = nfs_do_fsync(nfs_file_open_context(iocb->ki_filp), inode);
 480                 if (err < 0)
 481                         result = err;
 482         }
 483 out:
 484         return result;
 485
 486 out_swapfile:
 487         printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
 488         goto out;
 489 }
 490
 491 static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
 492 {
 493         struct inode *inode = filp->f_mapping->host;
 494         int status = 0;
 495
 496         lock_kernel();
 497         /* Try local locking first */
 498         posix_test_lock(filp, fl);
 499         if (fl->fl_type != F_UNLCK) {
 500                 /* found a conflict */
 501                 goto out;
 502         }
 503
 504         if (nfs_have_delegation(inode, FMODE_READ))
 505                 goto out_noconflict;
 506
 507         if (NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)
 508                 goto out_noconflict;
 509
 510         status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 511 out:
 512         unlock_kernel();
 513         return status;
 514 out_noconflict:
 515         fl->fl_type = F_UNLCK;
 516         goto out;
 517 }
 518
 519 static int do_vfs_lock(struct file *file, struct file_lock *fl)
 520 {
 521         int res = 0;
 522         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 523                 case FL_POSIX:
 524                         res = posix_lock_file_wait(file, fl);
 525                         break;
 526                 case FL_FLOCK:
 527                         res = flock_lock_file_wait(file, fl);
 528                         break;
 529                 default:
 530                         BUG();
 531         }
 532         if (res < 0)
 533                 dprintk(KERN_WARNING "%s: VFS is out of sync with lock manager"
 534                         " - error %d!\n",
 535                                 __FUNCTION__, res);
 536         return res;
 537 }
 538
 539 static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
 540 {
 541         struct inode *inode = filp->f_mapping->host;
 542         int status;
 543
 544         /*
 545          * Flush all pending writes before doing anything
 546          * with locks..
 547          */
 548         nfs_sync_mapping(filp->f_mapping);
 549
 550         /* NOTE: special case
 551          *      If we're signalled while cleaning up locks on process exit, we
 552          *      still need to complete the unlock.
 553          */
 554         lock_kernel();
 555         /* Use local locking if mounted with "-onolock" */
 556         if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM))
 557                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 558         else
 559                 status = do_vfs_lock(filp, fl);
 560         unlock_kernel();
 561         return status;
 562 }
 563
 564 static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
 565 {
 566         struct inode *inode = filp->f_mapping->host;
 567         int status;
 568
 569         /*
 570          * Flush all pending writes before doing anything
 571          * with locks..
 572          */
 573         status = nfs_sync_mapping(filp->f_mapping);
 574         if (status != 0)
 575                 goto out;
 576
 577         lock_kernel();
 578         /* Use local locking if mounted with "-onolock" */
 579         if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)) {
 580                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
 581                 /* If we were signalled we still need to ensure that
 582                  * we clean up any state on the server. We therefore
 583                  * record the lock call as having succeeded in order to
 584                  * ensure that locks_remove_posix() cleans it out when
 585                  * the process exits.
 586                  */
 587                 if (status == -EINTR || status == -ERESTARTSYS)
 588                         do_vfs_lock(filp, fl);
 589         } else
 590                 status = do_vfs_lock(filp, fl);
 591         unlock_kernel();
 592         if (status < 0)
 593                 goto out;
 594         /*
 595          * Make sure we clear the cache whenever we try to get the lock.
 596          * This makes locking act as a cache coherency point.
 597          */
 598         nfs_sync_mapping(filp->f_mapping);
 599         nfs_zap_caches(inode);
 600 out:
 601         return status;
 602 }
 603
 604 /*
 605  * Lock a (portion of) a file
 606  */
 607 static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
 608 {
 609         struct inode * inode = filp->f_mapping->host;
 610
 611         dprintk("NFS: nfs_lock(f=%s/%ld, t=%x, fl=%x, r=%Ld:%Ld)\n",
 612                         inode->i_sb->s_id, inode->i_ino,
 613                         fl->fl_type, fl->fl_flags,
 614                         (long long)fl->fl_start, (long long)fl->fl_end);
 615         nfs_inc_stats(inode, NFSIOS_VFSLOCK);
 616
 617         /* No mandatory locks over NFS */
 618         if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
 619                 return -ENOLCK;
 620
 621         if (IS_GETLK(cmd))
 622                 return do_getlk(filp, cmd, fl);
 623         if (fl->fl_type == F_UNLCK)
 624                 return do_unlk(filp, cmd, fl);
 625         return do_setlk(filp, cmd, fl);
 626 }
 627
 628 /*
 629  * Lock a (portion of) a file
 630  */
 631 static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
 632 {
 633         dprintk("NFS: nfs_flock(f=%s/%ld, t=%x, fl=%x)\n",
 634                         filp->f_path.dentry->d_inode->i_sb->s_id,
 635                         filp->f_path.dentry->d_inode->i_ino,
 636                         fl->fl_type, fl->fl_flags);
 637
 638         /*
 639          * No BSD flocks over NFS allowed.
 640          * Note: we could try to fake a POSIX lock request here by
 641          * using ((u32) filp | 0x80000000) or some such as the pid.
 642          * Not sure whether that would be unique, though, or whether
 643          * that would break in other places.
 644          */
 645         if (!(fl->fl_flags & FL_FLOCK))
 646                 return -ENOLCK;
 647
 648         /* We're simulating flock() locks using posix locks on the server */
 649         fl->fl_owner = (fl_owner_t)filp;
 650         fl->fl_start = 0;
 651         fl->fl_end = OFFSET_MAX;
 652
 653         if (fl->fl_type == F_UNLCK)
 654                 return do_unlk(filp, cmd, fl);
 655         return do_setlk(filp, cmd, fl);
 656 }
 657
 658 static int nfs_setlease(struct file *file, long arg, struct file_lock **fl)
 659 {
 660         /*
 661          * There is no protocol support for leases, so we have no way
 662          * to implement them correctly in the face of opens by other
 663          * clients.
 664          */
 665         return -EINVAL;
 666 }