fs/overlayfs/file.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2017 Red Hat, Inc.
   4  */
   5
   6 #include <linux/cred.h>
   7 #include <linux/file.h>
   8 #include <linux/mount.h>
   9 #include <linux/xattr.h>
  10 #include <linux/uio.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/splice.h>
  13 #include <linux/security.h>
  14 #include <linux/mm.h>
  15 #include <linux/fs.h>
  16 #include "overlayfs.h"
  17
  18 struct ovl_aio_req {
  19         struct kiocb iocb;
  20         refcount_t ref;
  21         struct kiocb *orig_iocb;
  22         struct fd fd;
  23 };
  24
  25 static struct kmem_cache *ovl_aio_request_cachep;
  26
  27 static char ovl_whatisit(struct inode *inode, struct inode *realinode)
  28 {
  29         if (realinode != ovl_inode_upper(inode))
  30                 return 'l';
  31         if (ovl_has_upperdata(inode))
  32                 return 'u';
  33         else
  34                 return 'm';
  35 }
  36
  37 /* No atime modification on underlying */
  38 #define OVL_OPEN_FLAGS (O_NOATIME)
  39
  40 static struct file *ovl_open_realfile(const struct file *file,
  41                                       const struct path *realpath)
  42 {
  43         struct inode *realinode = d_inode(realpath->dentry);
  44         struct inode *inode = file_inode(file);
  45         struct mnt_idmap *real_idmap;
  46         struct file *realfile;
  47         const struct cred *old_cred;
  48         int flags = file->f_flags | OVL_OPEN_FLAGS;
  49         int acc_mode = ACC_MODE(flags);
  50         int err;
  51
  52         if (flags & O_APPEND)
  53                 acc_mode |= MAY_APPEND;
  54
  55         old_cred = ovl_override_creds(inode->i_sb);
  56         real_idmap = mnt_idmap(realpath->mnt);
  57         err = inode_permission(real_idmap, realinode, MAY_OPEN | acc_mode);
  58         if (err) {
  59                 realfile = ERR_PTR(err);
  60         } else {
  61                 if (!inode_owner_or_capable(real_idmap, realinode))
  62                         flags &= ~O_NOATIME;
  63
  64                 realfile = backing_file_open(&file->f_path, flags, realpath,
  65                                              current_cred());
  66         }
  67         revert_creds(old_cred);
  68
  69         pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
  70                  file, file, ovl_whatisit(inode, realinode), file->f_flags,
  71                  realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
  72
  73         return realfile;
  74 }
  75
  76 #define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
  77
  78 static int ovl_change_flags(struct file *file, unsigned int flags)
  79 {
  80         struct inode *inode = file_inode(file);
  81         int err;
  82
  83         flags &= OVL_SETFL_MASK;
  84
  85         if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
  86                 return -EPERM;
  87
  88         if ((flags & O_DIRECT) && !(file->f_mode & FMODE_CAN_ODIRECT))
  89                 return -EINVAL;
  90
  91         if (file->f_op->check_flags) {
  92                 err = file->f_op->check_flags(flags);
  93                 if (err)
  94                         return err;
  95         }
  96
  97         spin_lock(&file->f_lock);
  98         file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
  99         file->f_iocb_flags = iocb_flags(file);
 100         spin_unlock(&file->f_lock);
 101
 102         return 0;
 103 }
 104
 105 static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
 106                                bool allow_meta)
 107 {
 108         struct dentry *dentry = file_dentry(file);
 109         struct path realpath;
 110         int err;
 111
 112         real->flags = 0;
 113         real->file = file->private_data;
 114
 115         if (allow_meta) {
 116                 ovl_path_real(dentry, &realpath);
 117         } else {
 118                 /* lazy lookup and verify of lowerdata */
 119                 err = ovl_verify_lowerdata(dentry);
 120                 if (err)
 121                         return err;
 122
 123                 ovl_path_realdata(dentry, &realpath);
 124         }
 125         if (!realpath.dentry)
 126                 return -EIO;
 127
 128         /* Has it been copied up since we'd opened it? */
 129         if (unlikely(file_inode(real->file) != d_inode(realpath.dentry))) {
 130                 real->flags = FDPUT_FPUT;
 131                 real->file = ovl_open_realfile(file, &realpath);
 132
 133                 return PTR_ERR_OR_ZERO(real->file);
 134         }
 135
 136         /* Did the flags change since open? */
 137         if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
 138                 return ovl_change_flags(real->file, file->f_flags);
 139
 140         return 0;
 141 }
 142
 143 static int ovl_real_fdget(const struct file *file, struct fd *real)
 144 {
 145         if (d_is_dir(file_dentry(file))) {
 146                 real->flags = 0;
 147                 real->file = ovl_dir_real_file(file, false);
 148
 149                 return PTR_ERR_OR_ZERO(real->file);
 150         }
 151
 152         return ovl_real_fdget_meta(file, real, false);
 153 }
 154
 155 static int ovl_open(struct inode *inode, struct file *file)
 156 {
 157         struct dentry *dentry = file_dentry(file);
 158         struct file *realfile;
 159         struct path realpath;
 160         int err;
 161
 162         /* lazy lookup and verify lowerdata */
 163         err = ovl_verify_lowerdata(dentry);
 164         if (err)
 165                 return err;
 166
 167         err = ovl_maybe_copy_up(dentry, file->f_flags);
 168         if (err)
 169                 return err;
 170
 171         /* No longer need these flags, so don't pass them on to underlying fs */
 172         file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 173
 174         ovl_path_realdata(dentry, &realpath);
 175         if (!realpath.dentry)
 176                 return -EIO;
 177
 178         realfile = ovl_open_realfile(file, &realpath);
 179         if (IS_ERR(realfile))
 180                 return PTR_ERR(realfile);
 181
 182         file->private_data = realfile;
 183
 184         return 0;
 185 }
 186
 187 static int ovl_release(struct inode *inode, struct file *file)
 188 {
 189         fput(file->private_data);
 190
 191         return 0;
 192 }
 193
 194 static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
 195 {
 196         struct inode *inode = file_inode(file);
 197         struct fd real;
 198         const struct cred *old_cred;
 199         loff_t ret;
 200
 201         /*
 202          * The two special cases below do not need to involve real fs,
 203          * so we can optimizing concurrent callers.
 204          */
 205         if (offset == 0) {
 206                 if (whence == SEEK_CUR)
 207                         return file->f_pos;
 208
 209                 if (whence == SEEK_SET)
 210                         return vfs_setpos(file, 0, 0);
 211         }
 212
 213         ret = ovl_real_fdget(file, &real);
 214         if (ret)
 215                 return ret;
 216
 217         /*
 218          * Overlay file f_pos is the master copy that is preserved
 219          * through copy up and modified on read/write, but only real
 220          * fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
 221          * limitations that are more strict than ->s_maxbytes for specific
 222          * files, so we use the real file to perform seeks.
 223          */
 224         ovl_inode_lock(inode);
 225         real.file->f_pos = file->f_pos;
 226
 227         old_cred = ovl_override_creds(inode->i_sb);
 228         ret = vfs_llseek(real.file, offset, whence);
 229         revert_creds(old_cred);
 230
 231         file->f_pos = real.file->f_pos;
 232         ovl_inode_unlock(inode);
 233
 234         fdput(real);
 235
 236         return ret;
 237 }
 238
 239 static void ovl_file_accessed(struct file *file)
 240 {
 241         struct inode *inode, *upperinode;
 242         struct timespec64 ctime, uctime;
 243
 244         if (file->f_flags & O_NOATIME)
 245                 return;
 246
 247         inode = file_inode(file);
 248         upperinode = ovl_inode_upper(inode);
 249
 250         if (!upperinode)
 251                 return;
 252
 253         ctime = inode_get_ctime(inode);
 254         uctime = inode_get_ctime(upperinode);
 255         if ((!timespec64_equal(&inode->i_mtime, &upperinode->i_mtime) ||
 256              !timespec64_equal(&ctime, &uctime))) {
 257                 inode->i_mtime = upperinode->i_mtime;
 258                 inode_set_ctime_to_ts(inode, uctime);
 259         }
 260
 261         touch_atime(&file->f_path);
 262 }
 263
 264 static rwf_t ovl_iocb_to_rwf(int ifl)
 265 {
 266         rwf_t flags = 0;
 267
 268         if (ifl & IOCB_NOWAIT)
 269                 flags |= RWF_NOWAIT;
 270         if (ifl & IOCB_HIPRI)
 271                 flags |= RWF_HIPRI;
 272         if (ifl & IOCB_DSYNC)
 273                 flags |= RWF_DSYNC;
 274         if (ifl & IOCB_SYNC)
 275                 flags |= RWF_SYNC;
 276
 277         return flags;
 278 }
 279
 280 static inline void ovl_aio_put(struct ovl_aio_req *aio_req)
 281 {
 282         if (refcount_dec_and_test(&aio_req->ref)) {
 283                 fdput(aio_req->fd);
 284                 kmem_cache_free(ovl_aio_request_cachep, aio_req);
 285         }
 286 }
 287
 288 static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req)
 289 {
 290         struct kiocb *iocb = &aio_req->iocb;
 291         struct kiocb *orig_iocb = aio_req->orig_iocb;
 292
 293         if (iocb->ki_flags & IOCB_WRITE) {
 294                 struct inode *inode = file_inode(orig_iocb->ki_filp);
 295
 296                 kiocb_end_write(iocb);
 297                 ovl_copyattr(inode);
 298         }
 299
 300         orig_iocb->ki_pos = iocb->ki_pos;
 301         ovl_aio_put(aio_req);
 302 }
 303
 304 static void ovl_aio_rw_complete(struct kiocb *iocb, long res)
 305 {
 306         struct ovl_aio_req *aio_req = container_of(iocb,
 307                                                    struct ovl_aio_req, iocb);
 308         struct kiocb *orig_iocb = aio_req->orig_iocb;
 309
 310         ovl_aio_cleanup_handler(aio_req);
 311         orig_iocb->ki_complete(orig_iocb, res);
 312 }
 313
 314 static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 315 {
 316         struct file *file = iocb->ki_filp;
 317         struct fd real;
 318         const struct cred *old_cred;
 319         ssize_t ret;
 320
 321         if (!iov_iter_count(iter))
 322                 return 0;
 323
 324         ret = ovl_real_fdget(file, &real);
 325         if (ret)
 326                 return ret;
 327
 328         ret = -EINVAL;
 329         if (iocb->ki_flags & IOCB_DIRECT &&
 330             !(real.file->f_mode & FMODE_CAN_ODIRECT))
 331                 goto out_fdput;
 332
 333         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 334         if (is_sync_kiocb(iocb)) {
 335                 ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
 336                                     ovl_iocb_to_rwf(iocb->ki_flags));
 337         } else {
 338                 struct ovl_aio_req *aio_req;
 339
 340                 ret = -ENOMEM;
 341                 aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
 342                 if (!aio_req)
 343                         goto out;
 344
 345                 aio_req->fd = real;
 346                 real.flags = 0;
 347                 aio_req->orig_iocb = iocb;
 348                 kiocb_clone(&aio_req->iocb, iocb, real.file);
 349                 aio_req->iocb.ki_complete = ovl_aio_rw_complete;
 350                 refcount_set(&aio_req->ref, 2);
 351                 ret = vfs_iocb_iter_read(real.file, &aio_req->iocb, iter);
 352                 ovl_aio_put(aio_req);
 353                 if (ret != -EIOCBQUEUED)
 354                         ovl_aio_cleanup_handler(aio_req);
 355         }
 356 out:
 357         revert_creds(old_cred);
 358         ovl_file_accessed(file);
 359 out_fdput:
 360         fdput(real);
 361
 362         return ret;
 363 }
 364
 365 static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 366 {
 367         struct file *file = iocb->ki_filp;
 368         struct inode *inode = file_inode(file);
 369         struct fd real;
 370         const struct cred *old_cred;
 371         ssize_t ret;
 372         int ifl = iocb->ki_flags;
 373
 374         if (!iov_iter_count(iter))
 375                 return 0;
 376
 377         inode_lock(inode);
 378         /* Update mode */
 379         ovl_copyattr(inode);
 380         ret = file_remove_privs(file);
 381         if (ret)
 382                 goto out_unlock;
 383
 384         ret = ovl_real_fdget(file, &real);
 385         if (ret)
 386                 goto out_unlock;
 387
 388         ret = -EINVAL;
 389         if (iocb->ki_flags & IOCB_DIRECT &&
 390             !(real.file->f_mode & FMODE_CAN_ODIRECT))
 391                 goto out_fdput;
 392
 393         if (!ovl_should_sync(OVL_FS(inode->i_sb)))
 394                 ifl &= ~(IOCB_DSYNC | IOCB_SYNC);
 395
 396         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 397         if (is_sync_kiocb(iocb)) {
 398                 file_start_write(real.file);
 399                 ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
 400                                      ovl_iocb_to_rwf(ifl));
 401                 file_end_write(real.file);
 402                 /* Update size */
 403                 ovl_copyattr(inode);
 404         } else {
 405                 struct ovl_aio_req *aio_req;
 406
 407                 ret = -ENOMEM;
 408                 aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
 409                 if (!aio_req)
 410                         goto out;
 411
 412                 aio_req->fd = real;
 413                 real.flags = 0;
 414                 aio_req->orig_iocb = iocb;
 415                 kiocb_clone(&aio_req->iocb, iocb, real.file);
 416                 aio_req->iocb.ki_flags = ifl;
 417                 aio_req->iocb.ki_complete = ovl_aio_rw_complete;
 418                 refcount_set(&aio_req->ref, 2);
 419                 kiocb_start_write(&aio_req->iocb);
 420                 ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter);
 421                 ovl_aio_put(aio_req);
 422                 if (ret != -EIOCBQUEUED)
 423                         ovl_aio_cleanup_handler(aio_req);
 424         }
 425 out:
 426         revert_creds(old_cred);
 427 out_fdput:
 428         fdput(real);
 429
 430 out_unlock:
 431         inode_unlock(inode);
 432
 433         return ret;
 434 }
 435
 436 static ssize_t ovl_splice_read(struct file *in, loff_t *ppos,
 437                                struct pipe_inode_info *pipe, size_t len,
 438                                unsigned int flags)
 439 {
 440         const struct cred *old_cred;
 441         struct fd real;
 442         ssize_t ret;
 443
 444         ret = ovl_real_fdget(in, &real);
 445         if (ret)
 446                 return ret;
 447
 448         old_cred = ovl_override_creds(file_inode(in)->i_sb);
 449         ret = vfs_splice_read(real.file, ppos, pipe, len, flags);
 450         revert_creds(old_cred);
 451         ovl_file_accessed(in);
 452
 453         fdput(real);
 454         return ret;
 455 }
 456
 457 /*
 458  * Calling iter_file_splice_write() directly from overlay's f_op may deadlock
 459  * due to lock order inversion between pipe->mutex in iter_file_splice_write()
 460  * and file_start_write(real.file) in ovl_write_iter().
 461  *
 462  * So do everything ovl_write_iter() does and call iter_file_splice_write() on
 463  * the real file.
 464  */
 465 static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
 466                                 loff_t *ppos, size_t len, unsigned int flags)
 467 {
 468         struct fd real;
 469         const struct cred *old_cred;
 470         struct inode *inode = file_inode(out);
 471         ssize_t ret;
 472
 473         inode_lock(inode);
 474         /* Update mode */
 475         ovl_copyattr(inode);
 476         ret = file_remove_privs(out);
 477         if (ret)
 478                 goto out_unlock;
 479
 480         ret = ovl_real_fdget(out, &real);
 481         if (ret)
 482                 goto out_unlock;
 483
 484         old_cred = ovl_override_creds(inode->i_sb);
 485         file_start_write(real.file);
 486
 487         ret = iter_file_splice_write(pipe, real.file, ppos, len, flags);
 488
 489         file_end_write(real.file);
 490         /* Update size */
 491         ovl_copyattr(inode);
 492         revert_creds(old_cred);
 493         fdput(real);
 494
 495 out_unlock:
 496         inode_unlock(inode);
 497
 498         return ret;
 499 }
 500
 501 static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 502 {
 503         struct fd real;
 504         const struct cred *old_cred;
 505         int ret;
 506
 507         ret = ovl_sync_status(OVL_FS(file_inode(file)->i_sb));
 508         if (ret <= 0)
 509                 return ret;
 510
 511         ret = ovl_real_fdget_meta(file, &real, !datasync);
 512         if (ret)
 513                 return ret;
 514
 515         /* Don't sync lower file for fear of receiving EROFS error */
 516         if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
 517                 old_cred = ovl_override_creds(file_inode(file)->i_sb);
 518                 ret = vfs_fsync_range(real.file, start, end, datasync);
 519                 revert_creds(old_cred);
 520         }
 521
 522         fdput(real);
 523
 524         return ret;
 525 }
 526
 527 static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
 528 {
 529         struct file *realfile = file->private_data;
 530         const struct cred *old_cred;
 531         int ret;
 532
 533         if (!realfile->f_op->mmap)
 534                 return -ENODEV;
 535
 536         if (WARN_ON(file != vma->vm_file))
 537                 return -EIO;
 538
 539         vma_set_file(vma, realfile);
 540
 541         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 542         ret = call_mmap(vma->vm_file, vma);
 543         revert_creds(old_cred);
 544         ovl_file_accessed(file);
 545
 546         return ret;
 547 }
 548
 549 static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 550 {
 551         struct inode *inode = file_inode(file);
 552         struct fd real;
 553         const struct cred *old_cred;
 554         int ret;
 555
 556         inode_lock(inode);
 557         /* Update mode */
 558         ovl_copyattr(inode);
 559         ret = file_remove_privs(file);
 560         if (ret)
 561                 goto out_unlock;
 562
 563         ret = ovl_real_fdget(file, &real);
 564         if (ret)
 565                 goto out_unlock;
 566
 567         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 568         ret = vfs_fallocate(real.file, mode, offset, len);
 569         revert_creds(old_cred);
 570
 571         /* Update size */
 572         ovl_copyattr(inode);
 573
 574         fdput(real);
 575
 576 out_unlock:
 577         inode_unlock(inode);
 578
 579         return ret;
 580 }
 581
 582 static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
 583 {
 584         struct fd real;
 585         const struct cred *old_cred;
 586         int ret;
 587
 588         ret = ovl_real_fdget(file, &real);
 589         if (ret)
 590                 return ret;
 591
 592         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 593         ret = vfs_fadvise(real.file, offset, len, advice);
 594         revert_creds(old_cred);
 595
 596         fdput(real);
 597
 598         return ret;
 599 }
 600
 601 enum ovl_copyop {
 602         OVL_COPY,
 603         OVL_CLONE,
 604         OVL_DEDUPE,
 605 };
 606
 607 static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
 608                             struct file *file_out, loff_t pos_out,
 609                             loff_t len, unsigned int flags, enum ovl_copyop op)
 610 {
 611         struct inode *inode_out = file_inode(file_out);
 612         struct fd real_in, real_out;
 613         const struct cred *old_cred;
 614         loff_t ret;
 615
 616         inode_lock(inode_out);
 617         if (op != OVL_DEDUPE) {
 618                 /* Update mode */
 619                 ovl_copyattr(inode_out);
 620                 ret = file_remove_privs(file_out);
 621                 if (ret)
 622                         goto out_unlock;
 623         }
 624
 625         ret = ovl_real_fdget(file_out, &real_out);
 626         if (ret)
 627                 goto out_unlock;
 628
 629         ret = ovl_real_fdget(file_in, &real_in);
 630         if (ret) {
 631                 fdput(real_out);
 632                 goto out_unlock;
 633         }
 634
 635         old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
 636         switch (op) {
 637         case OVL_COPY:
 638                 ret = vfs_copy_file_range(real_in.file, pos_in,
 639                                           real_out.file, pos_out, len, flags);
 640                 break;
 641
 642         case OVL_CLONE:
 643                 ret = vfs_clone_file_range(real_in.file, pos_in,
 644                                            real_out.file, pos_out, len, flags);
 645                 break;
 646
 647         case OVL_DEDUPE:
 648                 ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
 649                                                 real_out.file, pos_out, len,
 650                                                 flags);
 651                 break;
 652         }
 653         revert_creds(old_cred);
 654
 655         /* Update size */
 656         ovl_copyattr(inode_out);
 657
 658         fdput(real_in);
 659         fdput(real_out);
 660
 661 out_unlock:
 662         inode_unlock(inode_out);
 663
 664         return ret;
 665 }
 666
 667 static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
 668                                    struct file *file_out, loff_t pos_out,
 669                                    size_t len, unsigned int flags)
 670 {
 671         return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
 672                             OVL_COPY);
 673 }
 674
 675 static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in,
 676                                    struct file *file_out, loff_t pos_out,
 677                                    loff_t len, unsigned int remap_flags)
 678 {
 679         enum ovl_copyop op;
 680
 681         if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 682                 return -EINVAL;
 683
 684         if (remap_flags & REMAP_FILE_DEDUP)
 685                 op = OVL_DEDUPE;
 686         else
 687                 op = OVL_CLONE;
 688
 689         /*
 690          * Don't copy up because of a dedupe request, this wouldn't make sense
 691          * most of the time (data would be duplicated instead of deduplicated).
 692          */
 693         if (op == OVL_DEDUPE &&
 694             (!ovl_inode_upper(file_inode(file_in)) ||
 695              !ovl_inode_upper(file_inode(file_out))))
 696                 return -EPERM;
 697
 698         return ovl_copyfile(file_in, pos_in, file_out, pos_out, len,
 699                             remap_flags, op);
 700 }
 701
 702 static int ovl_flush(struct file *file, fl_owner_t id)
 703 {
 704         struct fd real;
 705         const struct cred *old_cred;
 706         int err;
 707
 708         err = ovl_real_fdget(file, &real);
 709         if (err)
 710                 return err;
 711
 712         if (real.file->f_op->flush) {
 713                 old_cred = ovl_override_creds(file_inode(file)->i_sb);
 714                 err = real.file->f_op->flush(real.file, id);
 715                 revert_creds(old_cred);
 716         }
 717         fdput(real);
 718
 719         return err;
 720 }
 721
 722 const struct file_operations ovl_file_operations = {
 723         .open           = ovl_open,
 724         .release        = ovl_release,
 725         .llseek         = ovl_llseek,
 726         .read_iter      = ovl_read_iter,
 727         .write_iter     = ovl_write_iter,
 728         .fsync          = ovl_fsync,
 729         .mmap           = ovl_mmap,
 730         .fallocate      = ovl_fallocate,
 731         .fadvise        = ovl_fadvise,
 732         .flush          = ovl_flush,
 733         .splice_read    = ovl_splice_read,
 734         .splice_write   = ovl_splice_write,
 735
 736         .copy_file_range        = ovl_copy_file_range,
 737         .remap_file_range       = ovl_remap_file_range,
 738 };
 739
 740 int __init ovl_aio_request_cache_init(void)
 741 {
 742         ovl_aio_request_cachep = kmem_cache_create("ovl_aio_req",
 743                                                    sizeof(struct ovl_aio_req),
 744                                                    0, SLAB_HWCACHE_ALIGN, NULL);
 745         if (!ovl_aio_request_cachep)
 746                 return -ENOMEM;
 747
 748         return 0;
 749 }
 750
 751 void ovl_aio_request_cache_destroy(void)
 752 {
 753         kmem_cache_destroy(ovl_aio_request_cachep);
 754 }