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         struct kiocb *orig_iocb;
  21         struct fd fd;
  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(realinode, MAY_OPEN | acc_mode);
  54         if (err) {
  55                 realfile = ERR_PTR(err);
  56         } else {
  57                 if (!inode_owner_or_capable(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 void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req)
 256 {
 257         struct kiocb *iocb = &aio_req->iocb;
 258         struct kiocb *orig_iocb = aio_req->orig_iocb;
 259
 260         if (iocb->ki_flags & IOCB_WRITE) {
 261                 struct inode *inode = file_inode(orig_iocb->ki_filp);
 262
 263                 /* Actually acquired in ovl_write_iter() */
 264                 __sb_writers_acquired(file_inode(iocb->ki_filp)->i_sb,
 265                                       SB_FREEZE_WRITE);
 266                 file_end_write(iocb->ki_filp);
 267                 ovl_copyattr(ovl_inode_real(inode), inode);
 268         }
 269
 270         orig_iocb->ki_pos = iocb->ki_pos;
 271         fdput(aio_req->fd);
 272         kmem_cache_free(ovl_aio_request_cachep, aio_req);
 273 }
 274
 275 static void ovl_aio_rw_complete(struct kiocb *iocb, long res, long res2)
 276 {
 277         struct ovl_aio_req *aio_req = container_of(iocb,
 278                                                    struct ovl_aio_req, iocb);
 279         struct kiocb *orig_iocb = aio_req->orig_iocb;
 280
 281         ovl_aio_cleanup_handler(aio_req);
 282         orig_iocb->ki_complete(orig_iocb, res, res2);
 283 }
 284
 285 static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 286 {
 287         struct file *file = iocb->ki_filp;
 288         struct fd real;
 289         const struct cred *old_cred;
 290         ssize_t ret;
 291
 292         if (!iov_iter_count(iter))
 293                 return 0;
 294
 295         ret = ovl_real_fdget(file, &real);
 296         if (ret)
 297                 return ret;
 298
 299         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 300         if (is_sync_kiocb(iocb)) {
 301                 ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
 302                                     ovl_iocb_to_rwf(iocb->ki_flags));
 303         } else {
 304                 struct ovl_aio_req *aio_req;
 305
 306                 ret = -ENOMEM;
 307                 aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
 308                 if (!aio_req)
 309                         goto out;
 310
 311                 aio_req->fd = real;
 312                 real.flags = 0;
 313                 aio_req->orig_iocb = iocb;
 314                 kiocb_clone(&aio_req->iocb, iocb, real.file);
 315                 aio_req->iocb.ki_complete = ovl_aio_rw_complete;
 316                 ret = vfs_iocb_iter_read(real.file, &aio_req->iocb, iter);
 317                 if (ret != -EIOCBQUEUED)
 318                         ovl_aio_cleanup_handler(aio_req);
 319         }
 320 out:
 321         revert_creds(old_cred);
 322         ovl_file_accessed(file);
 323
 324         fdput(real);
 325
 326         return ret;
 327 }
 328
 329 static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 330 {
 331         struct file *file = iocb->ki_filp;
 332         struct inode *inode = file_inode(file);
 333         struct fd real;
 334         const struct cred *old_cred;
 335         ssize_t ret;
 336         int ifl = iocb->ki_flags;
 337
 338         if (!iov_iter_count(iter))
 339                 return 0;
 340
 341         inode_lock(inode);
 342         /* Update mode */
 343         ovl_copyattr(ovl_inode_real(inode), inode);
 344         ret = file_remove_privs(file);
 345         if (ret)
 346                 goto out_unlock;
 347
 348         ret = ovl_real_fdget(file, &real);
 349         if (ret)
 350                 goto out_unlock;
 351
 352         if (!ovl_should_sync(OVL_FS(inode->i_sb)))
 353                 ifl &= ~(IOCB_DSYNC | IOCB_SYNC);
 354
 355         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 356         if (is_sync_kiocb(iocb)) {
 357                 file_start_write(real.file);
 358                 ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
 359                                      ovl_iocb_to_rwf(ifl));
 360                 file_end_write(real.file);
 361                 /* Update size */
 362                 ovl_copyattr(ovl_inode_real(inode), inode);
 363         } else {
 364                 struct ovl_aio_req *aio_req;
 365
 366                 ret = -ENOMEM;
 367                 aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
 368                 if (!aio_req)
 369                         goto out;
 370
 371                 file_start_write(real.file);
 372                 /* Pacify lockdep, same trick as done in aio_write() */
 373                 __sb_writers_release(file_inode(real.file)->i_sb,
 374                                      SB_FREEZE_WRITE);
 375                 aio_req->fd = real;
 376                 real.flags = 0;
 377                 aio_req->orig_iocb = iocb;
 378                 kiocb_clone(&aio_req->iocb, iocb, real.file);
 379                 aio_req->iocb.ki_flags = ifl;
 380                 aio_req->iocb.ki_complete = ovl_aio_rw_complete;
 381                 ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter);
 382                 if (ret != -EIOCBQUEUED)
 383                         ovl_aio_cleanup_handler(aio_req);
 384         }
 385 out:
 386         revert_creds(old_cred);
 387         fdput(real);
 388
 389 out_unlock:
 390         inode_unlock(inode);
 391
 392         return ret;
 393 }
 394
 395 static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 396 {
 397         struct fd real;
 398         const struct cred *old_cred;
 399         int ret;
 400
 401         if (!ovl_should_sync(OVL_FS(file_inode(file)->i_sb)))
 402                 return 0;
 403
 404         ret = ovl_real_fdget_meta(file, &real, !datasync);
 405         if (ret)
 406                 return ret;
 407
 408         /* Don't sync lower file for fear of receiving EROFS error */
 409         if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
 410                 old_cred = ovl_override_creds(file_inode(file)->i_sb);
 411                 ret = vfs_fsync_range(real.file, start, end, datasync);
 412                 revert_creds(old_cred);
 413         }
 414
 415         fdput(real);
 416
 417         return ret;
 418 }
 419
 420 static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
 421 {
 422         struct file *realfile = file->private_data;
 423         const struct cred *old_cred;
 424         int ret;
 425
 426         if (!realfile->f_op->mmap)
 427                 return -ENODEV;
 428
 429         if (WARN_ON(file != vma->vm_file))
 430                 return -EIO;
 431
 432         vma->vm_file = get_file(realfile);
 433
 434         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 435         ret = call_mmap(vma->vm_file, vma);
 436         revert_creds(old_cred);
 437
 438         if (ret) {
 439                 /* Drop reference count from new vm_file value */
 440                 fput(realfile);
 441         } else {
 442                 /* Drop reference count from previous vm_file value */
 443                 fput(file);
 444         }
 445
 446         ovl_file_accessed(file);
 447
 448         return ret;
 449 }
 450
 451 static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 452 {
 453         struct inode *inode = file_inode(file);
 454         struct fd real;
 455         const struct cred *old_cred;
 456         int ret;
 457
 458         ret = ovl_real_fdget(file, &real);
 459         if (ret)
 460                 return ret;
 461
 462         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 463         ret = vfs_fallocate(real.file, mode, offset, len);
 464         revert_creds(old_cred);
 465
 466         /* Update size */
 467         ovl_copyattr(ovl_inode_real(inode), inode);
 468
 469         fdput(real);
 470
 471         return ret;
 472 }
 473
 474 static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
 475 {
 476         struct fd real;
 477         const struct cred *old_cred;
 478         int ret;
 479
 480         ret = ovl_real_fdget(file, &real);
 481         if (ret)
 482                 return ret;
 483
 484         old_cred = ovl_override_creds(file_inode(file)->i_sb);
 485         ret = vfs_fadvise(real.file, offset, len, advice);
 486         revert_creds(old_cred);
 487
 488         fdput(real);
 489
 490         return ret;
 491 }
 492
 493 static long ovl_real_ioctl(struct file *file, unsigned int cmd,
 494                            unsigned long arg)
 495 {
 496         struct fd real;
 497         long ret;
 498
 499         ret = ovl_real_fdget(file, &real);
 500         if (ret)
 501                 return ret;
 502
 503         ret = security_file_ioctl(real.file, cmd, arg);
 504         if (!ret) {
 505                 /*
 506                  * Don't override creds, since we currently can't safely check
 507                  * permissions before doing so.
 508                  */
 509                 ret = vfs_ioctl(real.file, cmd, arg);
 510         }
 511
 512         fdput(real);
 513
 514         return ret;
 515 }
 516
 517 static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
 518                                 unsigned long arg)
 519 {
 520         long ret;
 521         struct inode *inode = file_inode(file);
 522
 523         if (!inode_owner_or_capable(inode))
 524                 return -EACCES;
 525
 526         ret = mnt_want_write_file(file);
 527         if (ret)
 528                 return ret;
 529
 530         inode_lock(inode);
 531
 532         /*
 533          * Prevent copy up if immutable and has no CAP_LINUX_IMMUTABLE
 534          * capability.
 535          */
 536         ret = -EPERM;
 537         if (!ovl_has_upperdata(inode) && IS_IMMUTABLE(inode) &&
 538             !capable(CAP_LINUX_IMMUTABLE))
 539                 goto unlock;
 540
 541         ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY);
 542         if (ret)
 543                 goto unlock;
 544
 545         ret = ovl_real_ioctl(file, cmd, arg);
 546
 547         ovl_copyflags(ovl_inode_real(inode), inode);
 548 unlock:
 549         inode_unlock(inode);
 550
 551         mnt_drop_write_file(file);
 552
 553         return ret;
 554
 555 }
 556
 557 long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 558 {
 559         long ret;
 560
 561         switch (cmd) {
 562         case FS_IOC_GETFLAGS:
 563         case FS_IOC_FSGETXATTR:
 564                 ret = ovl_real_ioctl(file, cmd, arg);
 565                 break;
 566
 567         case FS_IOC_FSSETXATTR:
 568         case FS_IOC_SETFLAGS:
 569                 ret = ovl_ioctl_set_flags(file, cmd, arg);
 570                 break;
 571
 572         default:
 573                 ret = -ENOTTY;
 574         }
 575
 576         return ret;
 577 }
 578
 579 #ifdef CONFIG_COMPAT
 580 long ovl_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 581 {
 582         switch (cmd) {
 583         case FS_IOC32_GETFLAGS:
 584                 cmd = FS_IOC_GETFLAGS;
 585                 break;
 586
 587         case FS_IOC32_SETFLAGS:
 588                 cmd = FS_IOC_SETFLAGS;
 589                 break;
 590
 591         default:
 592                 return -ENOIOCTLCMD;
 593         }
 594
 595         return ovl_ioctl(file, cmd, arg);
 596 }
 597 #endif
 598
 599 enum ovl_copyop {
 600         OVL_COPY,
 601         OVL_CLONE,
 602         OVL_DEDUPE,
 603 };
 604
 605 static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
 606                             struct file *file_out, loff_t pos_out,
 607                             loff_t len, unsigned int flags, enum ovl_copyop op)
 608 {
 609         struct inode *inode_out = file_inode(file_out);
 610         struct fd real_in, real_out;
 611         const struct cred *old_cred;
 612         loff_t ret;
 613
 614         ret = ovl_real_fdget(file_out, &real_out);
 615         if (ret)
 616                 return ret;
 617
 618         ret = ovl_real_fdget(file_in, &real_in);
 619         if (ret) {
 620                 fdput(real_out);
 621                 return ret;
 622         }
 623
 624         old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
 625         switch (op) {
 626         case OVL_COPY:
 627                 ret = vfs_copy_file_range(real_in.file, pos_in,
 628                                           real_out.file, pos_out, len, flags);
 629                 break;
 630
 631         case OVL_CLONE:
 632                 ret = vfs_clone_file_range(real_in.file, pos_in,
 633                                            real_out.file, pos_out, len, flags);
 634                 break;
 635
 636         case OVL_DEDUPE:
 637                 ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
 638                                                 real_out.file, pos_out, len,
 639                                                 flags);
 640                 break;
 641         }
 642         revert_creds(old_cred);
 643
 644         /* Update size */
 645         ovl_copyattr(ovl_inode_real(inode_out), inode_out);
 646
 647         fdput(real_in);
 648         fdput(real_out);
 649
 650         return ret;
 651 }
 652
 653 static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
 654                                    struct file *file_out, loff_t pos_out,
 655                                    size_t len, unsigned int flags)
 656 {
 657         return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
 658                             OVL_COPY);
 659 }
 660
 661 static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in,
 662                                    struct file *file_out, loff_t pos_out,
 663                                    loff_t len, unsigned int remap_flags)
 664 {
 665         enum ovl_copyop op;
 666
 667         if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 668                 return -EINVAL;
 669
 670         if (remap_flags & REMAP_FILE_DEDUP)
 671                 op = OVL_DEDUPE;
 672         else
 673                 op = OVL_CLONE;
 674
 675         /*
 676          * Don't copy up because of a dedupe request, this wouldn't make sense
 677          * most of the time (data would be duplicated instead of deduplicated).
 678          */
 679         if (op == OVL_DEDUPE &&
 680             (!ovl_inode_upper(file_inode(file_in)) ||
 681              !ovl_inode_upper(file_inode(file_out))))
 682                 return -EPERM;
 683
 684         return ovl_copyfile(file_in, pos_in, file_out, pos_out, len,
 685                             remap_flags, op);
 686 }
 687
 688 const struct file_operations ovl_file_operations = {
 689         .open           = ovl_open,
 690         .release        = ovl_release,
 691         .llseek         = ovl_llseek,
 692         .read_iter      = ovl_read_iter,
 693         .write_iter     = ovl_write_iter,
 694         .fsync          = ovl_fsync,
 695         .mmap           = ovl_mmap,
 696         .fallocate      = ovl_fallocate,
 697         .fadvise        = ovl_fadvise,
 698         .unlocked_ioctl = ovl_ioctl,
 699 #ifdef CONFIG_COMPAT
 700         .compat_ioctl   = ovl_compat_ioctl,
 701 #endif
 702         .splice_read    = generic_file_splice_read,
 703         .splice_write   = iter_file_splice_write,
 704
 705         .copy_file_range        = ovl_copy_file_range,
 706         .remap_file_range       = ovl_remap_file_range,
 707 };
 708
 709 int __init ovl_aio_request_cache_init(void)
 710 {
 711         ovl_aio_request_cachep = kmem_cache_create("ovl_aio_req",
 712                                                    sizeof(struct ovl_aio_req),
 713                                                    0, SLAB_HWCACHE_ALIGN, NULL);
 714         if (!ovl_aio_request_cachep)
 715                 return -ENOMEM;
 716
 717         return 0;
 718 }
 719
 720 void ovl_aio_request_cache_destroy(void)
 721 {
 722         kmem_cache_destroy(ovl_aio_request_cachep);
 723 }