root/fs/stat.c

DEFINITIONS

1. generic_fillattr
2. vfs_getattr_nosec
3. vfs_getattr
4. vfs_statx_fd
5. vfs_statx
6. cp_old_stat
7. SYSCALL_DEFINE2
8. SYSCALL_DEFINE2
9. SYSCALL_DEFINE2
10. cp_new_stat
11. SYSCALL_DEFINE2
12. SYSCALL_DEFINE2
13. SYSCALL_DEFINE4
14. SYSCALL_DEFINE2
15. do_readlinkat
16. SYSCALL_DEFINE4
17. SYSCALL_DEFINE3
18. cp_new_stat64
19. SYSCALL_DEFINE2
20. SYSCALL_DEFINE2
21. SYSCALL_DEFINE2
22. SYSCALL_DEFINE4
23. cp_statx
24. SYSCALL_DEFINE5
25. cp_compat_stat
26. COMPAT_SYSCALL_DEFINE2
27. COMPAT_SYSCALL_DEFINE2
28. COMPAT_SYSCALL_DEFINE4
29. COMPAT_SYSCALL_DEFINE2
30. __inode_add_bytes
31. inode_add_bytes
32. __inode_sub_bytes
33. inode_sub_bytes
34. inode_get_bytes
35. inode_set_bytes

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/stat.c
   4  *
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  */
   7 
   8 #include <linux/export.h>
   9 #include <linux/mm.h>
  10 #include <linux/errno.h>
  11 #include <linux/file.h>
  12 #include <linux/highuid.h>
  13 #include <linux/fs.h>
  14 #include <linux/namei.h>
  15 #include <linux/security.h>
  16 #include <linux/cred.h>
  17 #include <linux/syscalls.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/compat.h>
  20 
  21 #include <linux/uaccess.h>
  22 #include <asm/unistd.h>
  23 
  24 /**
  25  * generic_fillattr - Fill in the basic attributes from the inode struct
  26  * @inode: Inode to use as the source
  27  * @stat: Where to fill in the attributes
  28  *
  29  * Fill in the basic attributes in the kstat structure from data that's to be
  30  * found on the VFS inode structure.  This is the default if no getattr inode
  31  * operation is supplied.
  32  */
  33 void generic_fillattr(struct inode *inode, struct kstat *stat)
  34 {
  35         stat->dev = inode->i_sb->s_dev;
  36         stat->ino = inode->i_ino;
  37         stat->mode = inode->i_mode;
  38         stat->nlink = inode->i_nlink;
  39         stat->uid = inode->i_uid;
  40         stat->gid = inode->i_gid;
  41         stat->rdev = inode->i_rdev;
  42         stat->size = i_size_read(inode);
  43         stat->atime = inode->i_atime;
  44         stat->mtime = inode->i_mtime;
  45         stat->ctime = inode->i_ctime;
  46         stat->blksize = i_blocksize(inode);
  47         stat->blocks = inode->i_blocks;
  48 }
  49 EXPORT_SYMBOL(generic_fillattr);
  50 
  51 /**
  52  * vfs_getattr_nosec - getattr without security checks
  53  * @path: file to get attributes from
  54  * @stat: structure to return attributes in
  55  * @request_mask: STATX_xxx flags indicating what the caller wants
  56  * @query_flags: Query mode (KSTAT_QUERY_FLAGS)
  57  *
  58  * Get attributes without calling security_inode_getattr.
  59  *
  60  * Currently the only caller other than vfs_getattr is internal to the
  61  * filehandle lookup code, which uses only the inode number and returns no
  62  * attributes to any user.  Any other code probably wants vfs_getattr.
  63  */
  64 int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
  65                       u32 request_mask, unsigned int query_flags)
  66 {
  67         struct inode *inode = d_backing_inode(path->dentry);
  68 
  69         memset(stat, 0, sizeof(*stat));
  70         stat->result_mask |= STATX_BASIC_STATS;
  71         request_mask &= STATX_ALL;
  72         query_flags &= KSTAT_QUERY_FLAGS;
  73 
  74         /* allow the fs to override these if it really wants to */
  75         if (IS_NOATIME(inode))
  76                 stat->result_mask &= ~STATX_ATIME;
  77         if (IS_AUTOMOUNT(inode))
  78                 stat->attributes |= STATX_ATTR_AUTOMOUNT;
  79 
  80         if (inode->i_op->getattr)
  81                 return inode->i_op->getattr(path, stat, request_mask,
  82                                             query_flags);
  83 
  84         generic_fillattr(inode, stat);
  85         return 0;
  86 }
  87 EXPORT_SYMBOL(vfs_getattr_nosec);
  88 
  89 /*
  90  * vfs_getattr - Get the enhanced basic attributes of a file
  91  * @path: The file of interest
  92  * @stat: Where to return the statistics
  93  * @request_mask: STATX_xxx flags indicating what the caller wants
  94  * @query_flags: Query mode (KSTAT_QUERY_FLAGS)
  95  *
  96  * Ask the filesystem for a file's attributes.  The caller must indicate in
  97  * request_mask and query_flags to indicate what they want.
  98  *
  99  * If the file is remote, the filesystem can be forced to update the attributes
 100  * from the backing store by passing AT_STATX_FORCE_SYNC in query_flags or can
 101  * suppress the update by passing AT_STATX_DONT_SYNC.
 102  *
 103  * Bits must have been set in request_mask to indicate which attributes the
 104  * caller wants retrieving.  Any such attribute not requested may be returned
 105  * anyway, but the value may be approximate, and, if remote, may not have been
 106  * synchronised with the server.
 107  *
 108  * 0 will be returned on success, and a -ve error code if unsuccessful.
 109  */
 110 int vfs_getattr(const struct path *path, struct kstat *stat,
 111                 u32 request_mask, unsigned int query_flags)
 112 {
 113         int retval;
 114 
 115         retval = security_inode_getattr(path);
 116         if (retval)
 117                 return retval;
 118         return vfs_getattr_nosec(path, stat, request_mask, query_flags);
 119 }
 120 EXPORT_SYMBOL(vfs_getattr);
 121 
 122 /**
 123  * vfs_statx_fd - Get the enhanced basic attributes by file descriptor
 124  * @fd: The file descriptor referring to the file of interest
 125  * @stat: The result structure to fill in.
 126  * @request_mask: STATX_xxx flags indicating what the caller wants
 127  * @query_flags: Query mode (KSTAT_QUERY_FLAGS)
 128  *
 129  * This function is a wrapper around vfs_getattr().  The main difference is
 130  * that it uses a file descriptor to determine the file location.
 131  *
 132  * 0 will be returned on success, and a -ve error code if unsuccessful.
 133  */
 134 int vfs_statx_fd(unsigned int fd, struct kstat *stat,
 135                  u32 request_mask, unsigned int query_flags)
 136 {
 137         struct fd f;
 138         int error = -EBADF;
 139 
 140         if (query_flags & ~KSTAT_QUERY_FLAGS)
 141                 return -EINVAL;
 142 
 143         f = fdget_raw(fd);
 144         if (f.file) {
 145                 error = vfs_getattr(&f.file->f_path, stat,
 146                                     request_mask, query_flags);
 147                 fdput(f);
 148         }
 149         return error;
 150 }
 151 EXPORT_SYMBOL(vfs_statx_fd);
 152 
 153 /**
 154  * vfs_statx - Get basic and extra attributes by filename
 155  * @dfd: A file descriptor representing the base dir for a relative filename
 156  * @filename: The name of the file of interest
 157  * @flags: Flags to control the query
 158  * @stat: The result structure to fill in.
 159  * @request_mask: STATX_xxx flags indicating what the caller wants
 160  *
 161  * This function is a wrapper around vfs_getattr().  The main difference is
 162  * that it uses a filename and base directory to determine the file location.
 163  * Additionally, the use of AT_SYMLINK_NOFOLLOW in flags will prevent a symlink
 164  * at the given name from being referenced.
 165  *
 166  * 0 will be returned on success, and a -ve error code if unsuccessful.
 167  */
 168 int vfs_statx(int dfd, const char __user *filename, int flags,
 169               struct kstat *stat, u32 request_mask)
 170 {
 171         struct path path;
 172         int error = -EINVAL;
 173         unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
 174 
 175         if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 176                        AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
 177                 return -EINVAL;
 178 
 179         if (flags & AT_SYMLINK_NOFOLLOW)
 180                 lookup_flags &= ~LOOKUP_FOLLOW;
 181         if (flags & AT_NO_AUTOMOUNT)
 182                 lookup_flags &= ~LOOKUP_AUTOMOUNT;
 183         if (flags & AT_EMPTY_PATH)
 184                 lookup_flags |= LOOKUP_EMPTY;
 185 
 186 retry:
 187         error = user_path_at(dfd, filename, lookup_flags, &path);
 188         if (error)
 189                 goto out;
 190 
 191         error = vfs_getattr(&path, stat, request_mask, flags);
 192         path_put(&path);
 193         if (retry_estale(error, lookup_flags)) {
 194                 lookup_flags |= LOOKUP_REVAL;
 195                 goto retry;
 196         }
 197 out:
 198         return error;
 199 }
 200 EXPORT_SYMBOL(vfs_statx);
 201 
 202 
 203 #ifdef __ARCH_WANT_OLD_STAT
 204 
 205 /*
 206  * For backward compatibility?  Maybe this should be moved
 207  * into arch/i386 instead?
 208  */
 209 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
 210 {
 211         static int warncount = 5;
 212         struct __old_kernel_stat tmp;
 213 
 214         if (warncount > 0) {
 215                 warncount--;
 216                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
 217                         current->comm);
 218         } else if (warncount < 0) {
 219                 /* it's laughable, but... */
 220                 warncount = 0;
 221         }
 222 
 223         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
 224         tmp.st_dev = old_encode_dev(stat->dev);
 225         tmp.st_ino = stat->ino;
 226         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 227                 return -EOVERFLOW;
 228         tmp.st_mode = stat->mode;
 229         tmp.st_nlink = stat->nlink;
 230         if (tmp.st_nlink != stat->nlink)
 231                 return -EOVERFLOW;
 232         SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
 233         SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
 234         tmp.st_rdev = old_encode_dev(stat->rdev);
 235 #if BITS_PER_LONG == 32
 236         if (stat->size > MAX_NON_LFS)
 237                 return -EOVERFLOW;
 238 #endif
 239         tmp.st_size = stat->size;
 240         tmp.st_atime = stat->atime.tv_sec;
 241         tmp.st_mtime = stat->mtime.tv_sec;
 242         tmp.st_ctime = stat->ctime.tv_sec;
 243         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 244 }
 245 
 246 SYSCALL_DEFINE2(stat, const char __user *, filename,
 247                 struct __old_kernel_stat __user *, statbuf)
 248 {
 249         struct kstat stat;
 250         int error;
 251 
 252         error = vfs_stat(filename, &stat);
 253         if (error)
 254                 return error;
 255 
 256         return cp_old_stat(&stat, statbuf);
 257 }
 258 
 259 SYSCALL_DEFINE2(lstat, const char __user *, filename,
 260                 struct __old_kernel_stat __user *, statbuf)
 261 {
 262         struct kstat stat;
 263         int error;
 264 
 265         error = vfs_lstat(filename, &stat);
 266         if (error)
 267                 return error;
 268 
 269         return cp_old_stat(&stat, statbuf);
 270 }
 271 
 272 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
 273 {
 274         struct kstat stat;
 275         int error = vfs_fstat(fd, &stat);
 276 
 277         if (!error)
 278                 error = cp_old_stat(&stat, statbuf);
 279 
 280         return error;
 281 }
 282 
 283 #endif /* __ARCH_WANT_OLD_STAT */
 284 
 285 #ifdef __ARCH_WANT_NEW_STAT
 286 
 287 #if BITS_PER_LONG == 32
 288 #  define choose_32_64(a,b) a
 289 #else
 290 #  define choose_32_64(a,b) b
 291 #endif
 292 
 293 #define valid_dev(x)  choose_32_64(old_valid_dev(x),true)
 294 #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
 295 
 296 #ifndef INIT_STRUCT_STAT_PADDING
 297 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
 298 #endif
 299 
 300 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 301 {
 302         struct stat tmp;
 303 
 304         if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
 305                 return -EOVERFLOW;
 306 #if BITS_PER_LONG == 32
 307         if (stat->size > MAX_NON_LFS)
 308                 return -EOVERFLOW;
 309 #endif
 310 
 311         INIT_STRUCT_STAT_PADDING(tmp);
 312         tmp.st_dev = encode_dev(stat->dev);
 313         tmp.st_ino = stat->ino;
 314         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 315                 return -EOVERFLOW;
 316         tmp.st_mode = stat->mode;
 317         tmp.st_nlink = stat->nlink;
 318         if (tmp.st_nlink != stat->nlink)
 319                 return -EOVERFLOW;
 320         SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
 321         SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
 322         tmp.st_rdev = encode_dev(stat->rdev);
 323         tmp.st_size = stat->size;
 324         tmp.st_atime = stat->atime.tv_sec;
 325         tmp.st_mtime = stat->mtime.tv_sec;
 326         tmp.st_ctime = stat->ctime.tv_sec;
 327 #ifdef STAT_HAVE_NSEC
 328         tmp.st_atime_nsec = stat->atime.tv_nsec;
 329         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 330         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 331 #endif
 332         tmp.st_blocks = stat->blocks;
 333         tmp.st_blksize = stat->blksize;
 334         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 335 }
 336 
 337 SYSCALL_DEFINE2(newstat, const char __user *, filename,
 338                 struct stat __user *, statbuf)
 339 {
 340         struct kstat stat;
 341         int error = vfs_stat(filename, &stat);
 342 
 343         if (error)
 344                 return error;
 345         return cp_new_stat(&stat, statbuf);
 346 }
 347 
 348 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
 349                 struct stat __user *, statbuf)
 350 {
 351         struct kstat stat;
 352         int error;
 353 
 354         error = vfs_lstat(filename, &stat);
 355         if (error)
 356                 return error;
 357 
 358         return cp_new_stat(&stat, statbuf);
 359 }
 360 
 361 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
 362 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
 363                 struct stat __user *, statbuf, int, flag)
 364 {
 365         struct kstat stat;
 366         int error;
 367 
 368         error = vfs_fstatat(dfd, filename, &stat, flag);
 369         if (error)
 370                 return error;
 371         return cp_new_stat(&stat, statbuf);
 372 }
 373 #endif
 374 
 375 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
 376 {
 377         struct kstat stat;
 378         int error = vfs_fstat(fd, &stat);
 379 
 380         if (!error)
 381                 error = cp_new_stat(&stat, statbuf);
 382 
 383         return error;
 384 }
 385 #endif
 386 
 387 static int do_readlinkat(int dfd, const char __user *pathname,
 388                          char __user *buf, int bufsiz)
 389 {
 390         struct path path;
 391         int error;
 392         int empty = 0;
 393         unsigned int lookup_flags = LOOKUP_EMPTY;
 394 
 395         if (bufsiz <= 0)
 396                 return -EINVAL;
 397 
 398 retry:
 399         error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
 400         if (!error) {
 401                 struct inode *inode = d_backing_inode(path.dentry);
 402 
 403                 error = empty ? -ENOENT : -EINVAL;
 404                 /*
 405                  * AFS mountpoints allow readlink(2) but are not symlinks
 406                  */
 407                 if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
 408                         error = security_inode_readlink(path.dentry);
 409                         if (!error) {
 410                                 touch_atime(&path);
 411                                 error = vfs_readlink(path.dentry, buf, bufsiz);
 412                         }
 413                 }
 414                 path_put(&path);
 415                 if (retry_estale(error, lookup_flags)) {
 416                         lookup_flags |= LOOKUP_REVAL;
 417                         goto retry;
 418                 }
 419         }
 420         return error;
 421 }
 422 
 423 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 424                 char __user *, buf, int, bufsiz)
 425 {
 426         return do_readlinkat(dfd, pathname, buf, bufsiz);
 427 }
 428 
 429 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
 430                 int, bufsiz)
 431 {
 432         return do_readlinkat(AT_FDCWD, path, buf, bufsiz);
 433 }
 434 
 435 
 436 /* ---------- LFS-64 ----------- */
 437 #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
 438 
 439 #ifndef INIT_STRUCT_STAT64_PADDING
 440 #  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
 441 #endif
 442 
 443 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
 444 {
 445         struct stat64 tmp;
 446 
 447         INIT_STRUCT_STAT64_PADDING(tmp);
 448 #ifdef CONFIG_MIPS
 449         /* mips has weird padding, so we don't get 64 bits there */
 450         tmp.st_dev = new_encode_dev(stat->dev);
 451         tmp.st_rdev = new_encode_dev(stat->rdev);
 452 #else
 453         tmp.st_dev = huge_encode_dev(stat->dev);
 454         tmp.st_rdev = huge_encode_dev(stat->rdev);
 455 #endif
 456         tmp.st_ino = stat->ino;
 457         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 458                 return -EOVERFLOW;
 459 #ifdef STAT64_HAS_BROKEN_ST_INO
 460         tmp.__st_ino = stat->ino;
 461 #endif
 462         tmp.st_mode = stat->mode;
 463         tmp.st_nlink = stat->nlink;
 464         tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
 465         tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
 466         tmp.st_atime = stat->atime.tv_sec;
 467         tmp.st_atime_nsec = stat->atime.tv_nsec;
 468         tmp.st_mtime = stat->mtime.tv_sec;
 469         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 470         tmp.st_ctime = stat->ctime.tv_sec;
 471         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 472         tmp.st_size = stat->size;
 473         tmp.st_blocks = stat->blocks;
 474         tmp.st_blksize = stat->blksize;
 475         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 476 }
 477 
 478 SYSCALL_DEFINE2(stat64, const char __user *, filename,
 479                 struct stat64 __user *, statbuf)
 480 {
 481         struct kstat stat;
 482         int error = vfs_stat(filename, &stat);
 483 
 484         if (!error)
 485                 error = cp_new_stat64(&stat, statbuf);
 486 
 487         return error;
 488 }
 489 
 490 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
 491                 struct stat64 __user *, statbuf)
 492 {
 493         struct kstat stat;
 494         int error = vfs_lstat(filename, &stat);
 495 
 496         if (!error)
 497                 error = cp_new_stat64(&stat, statbuf);
 498 
 499         return error;
 500 }
 501 
 502 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
 503 {
 504         struct kstat stat;
 505         int error = vfs_fstat(fd, &stat);
 506 
 507         if (!error)
 508                 error = cp_new_stat64(&stat, statbuf);
 509 
 510         return error;
 511 }
 512 
 513 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
 514                 struct stat64 __user *, statbuf, int, flag)
 515 {
 516         struct kstat stat;
 517         int error;
 518 
 519         error = vfs_fstatat(dfd, filename, &stat, flag);
 520         if (error)
 521                 return error;
 522         return cp_new_stat64(&stat, statbuf);
 523 }
 524 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
 525 
 526 static noinline_for_stack int
 527 cp_statx(const struct kstat *stat, struct statx __user *buffer)
 528 {
 529         struct statx tmp;
 530 
 531         memset(&tmp, 0, sizeof(tmp));
 532 
 533         tmp.stx_mask = stat->result_mask;
 534         tmp.stx_blksize = stat->blksize;
 535         tmp.stx_attributes = stat->attributes;
 536         tmp.stx_nlink = stat->nlink;
 537         tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid);
 538         tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid);
 539         tmp.stx_mode = stat->mode;
 540         tmp.stx_ino = stat->ino;
 541         tmp.stx_size = stat->size;
 542         tmp.stx_blocks = stat->blocks;
 543         tmp.stx_attributes_mask = stat->attributes_mask;
 544         tmp.stx_atime.tv_sec = stat->atime.tv_sec;
 545         tmp.stx_atime.tv_nsec = stat->atime.tv_nsec;
 546         tmp.stx_btime.tv_sec = stat->btime.tv_sec;
 547         tmp.stx_btime.tv_nsec = stat->btime.tv_nsec;
 548         tmp.stx_ctime.tv_sec = stat->ctime.tv_sec;
 549         tmp.stx_ctime.tv_nsec = stat->ctime.tv_nsec;
 550         tmp.stx_mtime.tv_sec = stat->mtime.tv_sec;
 551         tmp.stx_mtime.tv_nsec = stat->mtime.tv_nsec;
 552         tmp.stx_rdev_major = MAJOR(stat->rdev);
 553         tmp.stx_rdev_minor = MINOR(stat->rdev);
 554         tmp.stx_dev_major = MAJOR(stat->dev);
 555         tmp.stx_dev_minor = MINOR(stat->dev);
 556 
 557         return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 558 }
 559 
 560 /**
 561  * sys_statx - System call to get enhanced stats
 562  * @dfd: Base directory to pathwalk from *or* fd to stat.
 563  * @filename: File to stat or "" with AT_EMPTY_PATH
 564  * @flags: AT_* flags to control pathwalk.
 565  * @mask: Parts of statx struct actually required.
 566  * @buffer: Result buffer.
 567  *
 568  * Note that fstat() can be emulated by setting dfd to the fd of interest,
 569  * supplying "" as the filename and setting AT_EMPTY_PATH in the flags.
 570  */
 571 SYSCALL_DEFINE5(statx,
 572                 int, dfd, const char __user *, filename, unsigned, flags,
 573                 unsigned int, mask,
 574                 struct statx __user *, buffer)
 575 {
 576         struct kstat stat;
 577         int error;
 578 
 579         if (mask & STATX__RESERVED)
 580                 return -EINVAL;
 581         if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
 582                 return -EINVAL;
 583 
 584         error = vfs_statx(dfd, filename, flags, &stat, mask);
 585         if (error)
 586                 return error;
 587 
 588         return cp_statx(&stat, buffer);
 589 }
 590 
 591 #ifdef CONFIG_COMPAT
 592 static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
 593 {
 594         struct compat_stat tmp;
 595 
 596         if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
 597                 return -EOVERFLOW;
 598 
 599         memset(&tmp, 0, sizeof(tmp));
 600         tmp.st_dev = old_encode_dev(stat->dev);
 601         tmp.st_ino = stat->ino;
 602         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 603                 return -EOVERFLOW;
 604         tmp.st_mode = stat->mode;
 605         tmp.st_nlink = stat->nlink;
 606         if (tmp.st_nlink != stat->nlink)
 607                 return -EOVERFLOW;
 608         SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
 609         SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
 610         tmp.st_rdev = old_encode_dev(stat->rdev);
 611         if ((u64) stat->size > MAX_NON_LFS)
 612                 return -EOVERFLOW;
 613         tmp.st_size = stat->size;
 614         tmp.st_atime = stat->atime.tv_sec;
 615         tmp.st_atime_nsec = stat->atime.tv_nsec;
 616         tmp.st_mtime = stat->mtime.tv_sec;
 617         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 618         tmp.st_ctime = stat->ctime.tv_sec;
 619         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 620         tmp.st_blocks = stat->blocks;
 621         tmp.st_blksize = stat->blksize;
 622         return copy_to_user(ubuf, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 623 }
 624 
 625 COMPAT_SYSCALL_DEFINE2(newstat, const char __user *, filename,
 626                        struct compat_stat __user *, statbuf)
 627 {
 628         struct kstat stat;
 629         int error;
 630 
 631         error = vfs_stat(filename, &stat);
 632         if (error)
 633                 return error;
 634         return cp_compat_stat(&stat, statbuf);
 635 }
 636 
 637 COMPAT_SYSCALL_DEFINE2(newlstat, const char __user *, filename,
 638                        struct compat_stat __user *, statbuf)
 639 {
 640         struct kstat stat;
 641         int error;
 642 
 643         error = vfs_lstat(filename, &stat);
 644         if (error)
 645                 return error;
 646         return cp_compat_stat(&stat, statbuf);
 647 }
 648 
 649 #ifndef __ARCH_WANT_STAT64
 650 COMPAT_SYSCALL_DEFINE4(newfstatat, unsigned int, dfd,
 651                        const char __user *, filename,
 652                        struct compat_stat __user *, statbuf, int, flag)
 653 {
 654         struct kstat stat;
 655         int error;
 656 
 657         error = vfs_fstatat(dfd, filename, &stat, flag);
 658         if (error)
 659                 return error;
 660         return cp_compat_stat(&stat, statbuf);
 661 }
 662 #endif
 663 
 664 COMPAT_SYSCALL_DEFINE2(newfstat, unsigned int, fd,
 665                        struct compat_stat __user *, statbuf)
 666 {
 667         struct kstat stat;
 668         int error = vfs_fstat(fd, &stat);
 669 
 670         if (!error)
 671                 error = cp_compat_stat(&stat, statbuf);
 672         return error;
 673 }
 674 #endif
 675 
 676 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
 677 void __inode_add_bytes(struct inode *inode, loff_t bytes)
 678 {
 679         inode->i_blocks += bytes >> 9;
 680         bytes &= 511;
 681         inode->i_bytes += bytes;
 682         if (inode->i_bytes >= 512) {
 683                 inode->i_blocks++;
 684                 inode->i_bytes -= 512;
 685         }
 686 }
 687 EXPORT_SYMBOL(__inode_add_bytes);
 688 
 689 void inode_add_bytes(struct inode *inode, loff_t bytes)
 690 {
 691         spin_lock(&inode->i_lock);
 692         __inode_add_bytes(inode, bytes);
 693         spin_unlock(&inode->i_lock);
 694 }
 695 
 696 EXPORT_SYMBOL(inode_add_bytes);
 697 
 698 void __inode_sub_bytes(struct inode *inode, loff_t bytes)
 699 {
 700         inode->i_blocks -= bytes >> 9;
 701         bytes &= 511;
 702         if (inode->i_bytes < bytes) {
 703                 inode->i_blocks--;
 704                 inode->i_bytes += 512;
 705         }
 706         inode->i_bytes -= bytes;
 707 }
 708 
 709 EXPORT_SYMBOL(__inode_sub_bytes);
 710 
 711 void inode_sub_bytes(struct inode *inode, loff_t bytes)
 712 {
 713         spin_lock(&inode->i_lock);
 714         __inode_sub_bytes(inode, bytes);
 715         spin_unlock(&inode->i_lock);
 716 }
 717 
 718 EXPORT_SYMBOL(inode_sub_bytes);
 719 
 720 loff_t inode_get_bytes(struct inode *inode)
 721 {
 722         loff_t ret;
 723 
 724         spin_lock(&inode->i_lock);
 725         ret = __inode_get_bytes(inode);
 726         spin_unlock(&inode->i_lock);
 727         return ret;
 728 }
 729 
 730 EXPORT_SYMBOL(inode_get_bytes);
 731 
 732 void inode_set_bytes(struct inode *inode, loff_t bytes)
 733 {
 734         /* Caller is here responsible for sufficient locking
 735          * (ie. inode->i_lock) */
 736         inode->i_blocks = bytes >> 9;
 737         inode->i_bytes = bytes & 511;
 738 }
 739 
 740 EXPORT_SYMBOL(inode_set_bytes);