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 };
  23
  24 static struct kmem_cache *ovl_aio_request_cachep;
  25
  26 static char ovl_whatisit(struct inode *inode, struct inode *realinode)
  27 {
  28         if (realinode != ovl_inode_upper(inode))
  29                 return 'l';
  30         if (ovl_has_upperdata(inode))
  31                 return 'u';
  32         else
  33                 return 'm';
  34 }
  35
  36 /* No atime modificaton nor notify on underlying */
  37 #define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
  38
  39 static struct file *ovl_open_realfile(const struct file *file,
  40                                       struct inode *realinode)
  41 {
  42         struct inode *inode = file_inode(file);
  43         struct file *realfile;
  44         const struct cred *old_cred;
  45         int flags = file->f_flags | OVL_OPEN_FLAGS;
  46         int acc_mode = ACC_MODE(flags);
  47         int err;
  48
  49         if (flags & O_APPEND)
  50                 acc_mode |= MAY_APPEND;
  51
  52         old_cred = ovl_override_creds(inode->i_sb);
  53         err = inode_permission(&init_user_ns, realinode, MAY_OPEN | acc_mode);
  54         if (err) {
  55                 realfile = ERR_PTR(err);
  56         } else {
  57                 if (!inode_owner_or_capable(&init_user_ns, realinode))
  58                         flags &= ~O_NOATIME;
  59
  60                 realfile = open_with_fake_path(&file->f_path, flags, realinode,
  61                                                current_cred());
  62         }
  63         revert_creds(old_cred);
  64
  65         pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
  66                  file, file, ovl_whatisit(inode, realinode), file->f_flags,
  67                  realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
  68
  69         return realfile;
  70 }
  71
  72 #define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
  73
  74 static int ovl_change_flags(struct file *file, unsigned int flags)
  75 {
  76         struct inode *inode = file_inode(file);
  77         int err;
  78
  79         flags &= OVL_SETFL_MASK;
  80
  81         if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
  82                 return -EPERM;
  83
  84         if (flags & O_DIRECT) {
  85                 if (!file->f_mapping->a_ops ||
  86                     !file->f_mapping->a_ops->direct_IO)
  87                         return -EINVAL;
  88         }
  89
  90         if (file->f_op->check_flags) {
  91                 err = file->f_op->check_flags(flags);
  92                 if (err)
  93                         return err;
  94         }
  95
  96         spin_lock(&file->f_lock);
  97         file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
  98         spin_unlock(&file->f_lock);
  99
 100         return 0;
 101 }
 102
 103 static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
 104                                bool allow_meta)
 105 {
 106         struct inode *inode = file_inode(file);
 107         struct inode *realinode;
 108
 109         real->flags = 0;
 110         real->file = file->private_data;
 111
 112         if (allow_meta)
 113                 realinode = ovl_inode_real(inode);
 114         else
 115                 realinode = ovl_inode_realdata(inode);
 116
 117         /* Has it been copied up since we'd opened it? */
 118         if (unlikely(file_inode(real->file) != realinode)) {
 119                 real->flags = FDPUT_FPUT;
 120                 real->file = ovl_open_realfile(file, realinode);
 121
 122                 return PTR_ERR_OR_ZERO(real->file);
 123         }
 124
 125         /* Did the flags change since open? */
 126         if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
 127                 return ovl_change_flags(real->file, file->f_flags);
 128
 129         return 0;
 130 }
 131
 132 static int ovl_real_fdget(const struct file *file, struct fd *real)
 133 {
 134         if (d_is_dir(file_dentry(file))) {
 135                 real->flags = 0;
 136                 real->file = ovl_dir_real_file(file, false);
 137
 138                 return PTR_ERR_OR_ZERO(real->file);
 139         }
 140
 141         return ovl_real_fdget_meta(file, real, false);
 142 }
 143
 144 static int ovl_open(struct inode *inode, struct file *file)
 145 {
 146         struct file *realfile;
 147         int err;
 148
 149         err = ovl_maybe_copy_up(file_dentry(file), file->f_flags);
 150         if (err)
 151                 return err;
 152
 153         /* No longer need these flags, so don't pass them on to underlying fs */
 154         file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 155
 156         realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
 157         if (IS_ERR(realfile))
 158                 return PTR_ERR(realfile);
 159
 160         file->private_data = realfile;
 161
 162         return 0;
 163 }
 164
 165 static int ovl_release(struct inode *inode, struct file *file)
 166 {
 167         fput(file->private_data);
 168
 169         return 0;
 170 }
 171
 172 static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
 173 {
 174         struct inode *inode = file_inode(file);
 175         struct fd real;
 176         const struct cred *old_cred;
 177         loff_t ret;
 178
 179         /*
 180          * The two special cases below do not need to involve real fs,
 181          * so we can optimizing concurrent callers.
 182          */
 183         if (offset == 0) {
 184                 if (whence == SEEK_CUR)
 185                         return file->f_pos;
 186
 187                 if (whence == SEEK_SET)
 188                         return vfs_setpos(file, 0, 0);
 189         }
 190
 191         ret = ovl_real_fdget(file, &real);
 192         if (ret)
 193                 return ret;
 194
 195         /*
 196          * Overlay file f_pos is the master copy that is preserved
 197          * through copy up and modified on read/write, but only real
 198          * fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
 199          * limitations that are more strict than ->s_maxbytes for specific
 200          * files, so we use the real file to perform seeks.
 201          */
 202         ovl_inode_lock(inode);
 203         real.file->f_pos = file->f_pos;
 204
 205         old_cred = ovl_override_creds(inode->i_sb);
 206         ret = vfs_llseek(real.file, offset, whence);
 207         revert_creds(old_cred);
 208
 209         file->f_pos = real.file->f_pos;
 210         ovl_inode_unlock(inode);
 211
 212         fdput(real);
 213
 214         return ret;
 215 }
 216
 217 static void ovl_file_accessed(struct file *file)
 218 {
 219         struct inode *inode, *upperinode;
 220
 221         if (file->f_flags & O_NOATIME)
 222                 return;
 223
 224         inode = file_inode(file);
 225         upperinode = ovl_inode_upper(inode);
 226
 227         if (!upperinode)
 228                 return;
 229
 230         if ((!timespec64_equal(&inode->i_mtime, &upperinode->i_mtime) ||
 231              !timespec64_equal(&inode->i_ctime, &upperinode->i_ctime))) {
 232                 inode->i_mtime = upperinode->i_mtime;
 233                 inode->i_ctime = upperinode->i_ctime;
 234         }
 235
 236         touch_atime(&file->f_path);
 237 }
 238
 239 static rwf_t ovl_iocb_to_rwf(int ifl)
 240 {
 241         rwf_t flags = 0;
 242
 243         if (ifl & IOCB_NOWAIT)
 244                 flags |= RWF_NOWAIT;
 245         if (ifl & IOCB_HIPRI)
 246                 flags |= RWF_HIPRI;
 247         if (ifl & IOCB_DSYNC)
 248                 flags |= RWF_DSYNC;
 249         if (ifl & IOCB_SYNC)
 250                 flags |= RWF_SYNC;
 251
 252         return flags;
 253 }
 254
 255 static inline void ovl_aio_put(struct ovl_aio_req *aio_req)
 256 {
 257         if (refcount_dec_and_test(&aio_req->ref)) {
 258                 fput(aio_req->iocb.ki_filp);
 259                 kmem_cache_free(ovl_aio_request_cachep, aio_req);
 260         }
 261 }
 262
 263 static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req)
 264 {
 265         struct kiocb *iocb = &aio_req->iocb;
 266         struct kiocb *orig_iocb = aio_req->orig_iocb;
 267
 268         if (iocb->ki_flags & IOCB_WRITE) {
 269                 struct inode *inode = file_inode(orig_iocb->ki_filp);
 270
 271                 /* Actually acquired in ovl_write_iter() */
 272                 __sb_writers_acquired(file_inode(iocb->ki_filp)->i_sb,
 273                                       SB_FREEZE_WRITE);
 274                 file_end_write(iocb->ki_filp);
 275                 ovl_copyattr(inode);
 276         }
 277
 278         orig_iocb->ki_pos = iocb->ki_pos;
 279         ovl_aio_put(aio_req);
 280 }
 281
 282 static void ovl_aio_rw_complete(struct kiocb *iocb, long res, long res2)
 283 {
 284         struct ovl_aio_req *aio_req = container_of(iocb,
 285                                                    struct ovl_aio_req, iocb);
 286         struct kiocb *orig_iocb = aio_req->orig_iocb;
 287
 288         ovl_aio_cleanup_handler(aio_req);
 289         orig_iocb->ki_complete(orig_iocb, res, res2);
 290 }
 291
 292 static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 293 {
 294         struct file *file = iocb->ki_filp;
 295         struct fd real;
 296         const struct cred *old_cred;
 297         ssize_t ret;
 298
 299         if (!iov_iter_count(iter))
 300                 return 0;
 301
 302         ret = ovl_real_fdget(file, &real);
 303         if (ret)
 304                 return ret;
 305
 306         ret = -EINVAL;
 307         if (iocb->ki_flags & IOCB_DIRECT &&
 308             (!real.file->f_mapping->a_ops ||
 309              !real.file->f_mapping->a_ops->direct_IO))
 310                 goto out_fdput;
 311
 312         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 313         if (is_sync_kiocb(iocb)) {
 314                 ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
 315                                     ovl_iocb_to_rwf(iocb->ki_flags));
 316         } else {
 317                 struct ovl_aio_req *aio_req;
 318
 319                 ret = -ENOMEM;
 320                 aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
 321                 if (!aio_req)
 322                         goto out;
 323
 324                 real.flags = 0;
 325                 aio_req->orig_iocb = iocb;
 326                 kiocb_clone(&aio_req->iocb, iocb, get_file(real.file));
 327                 aio_req->iocb.ki_complete = ovl_aio_rw_complete;
 328                 refcount_set(&aio_req->ref, 2);
 329                 ret = vfs_iocb_iter_read(real.file, &aio_req->iocb, iter);
 330                 ovl_aio_put(aio_req);
 331                 if (ret != -EIOCBQUEUED)
 332                         ovl_aio_cleanup_handler(aio_req);
 333         }
 334 out:
 335         revert_creds(old_cred);
 336         ovl_file_accessed(file);
 337 out_fdput:
 338         fdput(real);
 339
 340         return ret;
 341 }
 342
 343 static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 344 {
 345         struct file *file = iocb->ki_filp;
 346         struct inode *inode = file_inode(file);
 347         struct fd real;
 348         const struct cred *old_cred;
 349         ssize_t ret;
 350         int ifl = iocb->ki_flags;
 351
 352         if (!iov_iter_count(iter))
 353                 return 0;
 354
 355         inode_lock(inode);
 356         /* Update mode */
 357         ovl_copyattr(inode);
 358         ret = file_remove_privs(file);
 359         if (ret)
 360                 goto out_unlock;
 361
 362         ret = ovl_real_fdget(file, &real);
 363         if (ret)
 364                 goto out_unlock;
 365
 366         ret = -EINVAL;
 367         if (iocb->ki_flags & IOCB_DIRECT &&
 368             (!real.file->f_mapping->a_ops ||
 369              !real.file->f_mapping->a_ops->direct_IO))
 370                 goto out_fdput;
 371
 372         if (!ovl_should_sync(OVL_FS(inode->i_sb)))
 373                 ifl &= ~(IOCB_DSYNC | IOCB_SYNC);
 374
 375         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 376         if (is_sync_kiocb(iocb)) {
 377                 file_start_write(real.file);
 378                 ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
 379                                      ovl_iocb_to_rwf(ifl));
 380                 file_end_write(real.file);
 381                 /* Update size */
 382                 ovl_copyattr(inode);
 383         } else {
 384                 struct ovl_aio_req *aio_req;
 385
 386                 ret = -ENOMEM;
 387                 aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
 388                 if (!aio_req)
 389                         goto out;
 390
 391                 file_start_write(real.file);
 392                 /* Pacify lockdep, same trick as done in aio_write() */
 393                 __sb_writers_release(file_inode(real.file)->i_sb,
 394                                      SB_FREEZE_WRITE);
 395                 real.flags = 0;
 396                 aio_req->orig_iocb = iocb;
 397                 kiocb_clone(&aio_req->iocb, iocb, get_file(real.file));
 398                 aio_req->iocb.ki_flags = ifl;
 399                 aio_req->iocb.ki_complete = ovl_aio_rw_complete;
 400                 refcount_set(&aio_req->ref, 2);
 401                 ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter);
 402                 ovl_aio_put(aio_req);
 403                 if (ret != -EIOCBQUEUED)
 404                         ovl_aio_cleanup_handler(aio_req);
 405         }
 406 out:
 407         revert_creds(old_cred);
 408 out_fdput:
 409         fdput(real);
 410
 411 out_unlock:
 412         inode_unlock(inode);
 413
 414         return ret;
 415 }
 416
 417 /*
 418  * Calling iter_file_splice_write() directly from overlay's f_op may deadlock
 419  * due to lock order inversion between pipe->mutex in iter_file_splice_write()
 420  * and file_start_write(real.file) in ovl_write_iter().
 421  *
 422  * So do everything ovl_write_iter() does and call iter_file_splice_write() on
 423  * the real file.
 424  */
 425 static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
 426                                 loff_t *ppos, size_t len, unsigned int flags)
 427 {
 428         struct fd real;
 429         const struct cred *old_cred;
 430         struct inode *inode = file_inode(out);
 431         ssize_t ret;
 432
 433         inode_lock(inode);
 434         /* Update mode */
 435         ovl_copyattr(inode);
 436         ret = file_remove_privs(out);
 437         if (ret)
 438                 goto out_unlock;
 439
 440         ret = ovl_real_fdget(out, &real);
 441         if (ret)
 442                 goto out_unlock;
 443
 444         old_cred = ovl_override_creds(inode->i_sb);
 445         file_start_write(real.file);
 446
 447         ret = iter_file_splice_write(pipe, real.file, ppos, len, flags);
 448
 449         file_end_write(real.file);
 450         /* Update size */
 451         ovl_copyattr(inode);
 452         revert_creds(old_cred);
 453         fdput(real);
 454
 455 out_unlock:
 456         inode_unlock(inode);
 457
 458         return ret;
 459 }
 460
 461 static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 462 {
 463         struct fd real;
 464         const struct cred *old_cred;
 465         int ret;
 466
 467         ret = ovl_sync_status(OVL_FS(file_inode(file)->i_sb));
 468         if (ret <= 0)
 469                 return ret;
 470
 471         ret = ovl_real_fdget_meta(file, &real, !datasync);
 472         if (ret)
 473                 return ret;
 474
 475         /* Don't sync lower file for fear of receiving EROFS error */
 476         if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
 477                 old_cred = ovl_override_creds(file_inode(file)->i_sb);
 478                 ret = vfs_fsync_range(real.file, start, end, datasync);
 479                 revert_creds(old_cred);
 480         }
 481
 482         fdput(real);
 483
 484         return ret;
 485 }
 486
 487 static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
 488 {
 489         struct file *realfile = file->private_data;
 490         const struct cred *old_cred;
 491         int ret;
 492
 493         if (!realfile->f_op->mmap)
 494                 return -ENODEV;
 495
 496         if (WARN_ON(file != vma->vm_file))
 497                 return -EIO;
 498
 499         vma_set_file(vma, realfile);
 500
 501         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 502         ret = call_mmap(vma->vm_file, vma);
 503         revert_creds(old_cred);
 504         ovl_file_accessed(file);
 505
 506         return ret;
 507 }
 508
 509 static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 510 {
 511         struct inode *inode = file_inode(file);
 512         struct fd real;
 513         const struct cred *old_cred;
 514         int ret;
 515
 516         inode_lock(inode);
 517         /* Update mode */
 518         ovl_copyattr(inode);
 519         ret = file_remove_privs(file);
 520         if (ret)
 521                 goto out_unlock;
 522
 523         ret = ovl_real_fdget(file, &real);
 524         if (ret)
 525                 goto out_unlock;
 526
 527         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 528         ret = vfs_fallocate(real.file, mode, offset, len);
 529         revert_creds(old_cred);
 530
 531         /* Update size */
 532         ovl_copyattr(inode);
 533
 534         fdput(real);
 535
 536 out_unlock:
 537         inode_unlock(inode);
 538
 539         return ret;
 540 }
 541
 542 static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
 543 {
 544         struct fd real;
 545         const struct cred *old_cred;
 546         int ret;
 547
 548         ret = ovl_real_fdget(file, &real);
 549         if (ret)
 550                 return ret;
 551
 552         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 553         ret = vfs_fadvise(real.file, offset, len, advice);
 554         revert_creds(old_cred);
 555
 556         fdput(real);
 557
 558         return ret;
 559 }
 560
 561 enum ovl_copyop {
 562         OVL_COPY,
 563         OVL_CLONE,
 564         OVL_DEDUPE,
 565 };
 566
 567 static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
 568                             struct file *file_out, loff_t pos_out,
 569                             loff_t len, unsigned int flags, enum ovl_copyop op)
 570 {
 571         struct inode *inode_out = file_inode(file_out);
 572         struct fd real_in, real_out;
 573         const struct cred *old_cred;
 574         loff_t ret;
 575
 576         inode_lock(inode_out);
 577         if (op != OVL_DEDUPE) {
 578                 /* Update mode */
 579                 ovl_copyattr(inode_out);
 580                 ret = file_remove_privs(file_out);
 581                 if (ret)
 582                         goto out_unlock;
 583         }
 584
 585         ret = ovl_real_fdget(file_out, &real_out);
 586         if (ret)
 587                 goto out_unlock;
 588
 589         ret = ovl_real_fdget(file_in, &real_in);
 590         if (ret) {
 591                 fdput(real_out);
 592                 goto out_unlock;
 593         }
 594
 595         old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
 596         switch (op) {
 597         case OVL_COPY:
 598                 ret = vfs_copy_file_range(real_in.file, pos_in,
 599                                           real_out.file, pos_out, len, flags);
 600                 break;
 601
 602         case OVL_CLONE:
 603                 ret = vfs_clone_file_range(real_in.file, pos_in,
 604                                            real_out.file, pos_out, len, flags);
 605                 break;
 606
 607         case OVL_DEDUPE:
 608                 ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
 609                                                 real_out.file, pos_out, len,
 610                                                 flags);
 611                 break;
 612         }
 613         revert_creds(old_cred);
 614
 615         /* Update size */
 616         ovl_copyattr(inode_out);
 617
 618         fdput(real_in);
 619         fdput(real_out);
 620
 621 out_unlock:
 622         inode_unlock(inode_out);
 623
 624         return ret;
 625 }
 626
 627 static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
 628                                    struct file *file_out, loff_t pos_out,
 629                                    size_t len, unsigned int flags)
 630 {
 631         return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
 632                             OVL_COPY);
 633 }
 634
 635 static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in,
 636                                    struct file *file_out, loff_t pos_out,
 637                                    loff_t len, unsigned int remap_flags)
 638 {
 639         enum ovl_copyop op;
 640
 641         if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 642                 return -EINVAL;
 643
 644         if (remap_flags & REMAP_FILE_DEDUP)
 645                 op = OVL_DEDUPE;
 646         else
 647                 op = OVL_CLONE;
 648
 649         /*
 650          * Don't copy up because of a dedupe request, this wouldn't make sense
 651          * most of the time (data would be duplicated instead of deduplicated).
 652          */
 653         if (op == OVL_DEDUPE &&
 654             (!ovl_inode_upper(file_inode(file_in)) ||
 655              !ovl_inode_upper(file_inode(file_out))))
 656                 return -EPERM;
 657
 658         return ovl_copyfile(file_in, pos_in, file_out, pos_out, len,
 659                             remap_flags, op);
 660 }
 661
 662 static int ovl_flush(struct file *file, fl_owner_t id)
 663 {
 664         struct fd real;
 665         const struct cred *old_cred;
 666         int err;
 667
 668         err = ovl_real_fdget(file, &real);
 669         if (err)
 670                 return err;
 671
 672         if (real.file->f_op->flush) {
 673                 old_cred = ovl_override_creds(file_inode(file)->i_sb);
 674                 err = real.file->f_op->flush(real.file, id);
 675                 revert_creds(old_cred);
 676         }
 677         fdput(real);
 678
 679         return err;
 680 }
 681
 682 const struct file_operations ovl_file_operations = {
 683         .open           = ovl_open,
 684         .release        = ovl_release,
 685         .llseek         = ovl_llseek,
 686         .read_iter      = ovl_read_iter,
 687         .write_iter     = ovl_write_iter,
 688         .fsync          = ovl_fsync,
 689         .mmap           = ovl_mmap,
 690         .fallocate      = ovl_fallocate,
 691         .fadvise        = ovl_fadvise,
 692         .flush          = ovl_flush,
 693         .splice_read    = generic_file_splice_read,
 694         .splice_write   = ovl_splice_write,
 695
 696         .copy_file_range        = ovl_copy_file_range,
 697         .remap_file_range       = ovl_remap_file_range,
 698 };
 699
 700 int __init ovl_aio_request_cache_init(void)
 701 {
 702         ovl_aio_request_cachep = kmem_cache_create("ovl_aio_req",
 703                                                    sizeof(struct ovl_aio_req),
 704                                                    0, SLAB_HWCACHE_ALIGN, NULL);
 705         if (!ovl_aio_request_cachep)
 706                 return -ENOMEM;
 707
 708         return 0;
 709 }
 710
 711 void ovl_aio_request_cache_destroy(void)
 712 {
 713         kmem_cache_destroy(ovl_aio_request_cachep);
 714 }