xref: /linux/fs/stat.c (revision 94e48d6aafef23143f92eadd010c505c49487576)
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 #include "internal.h"
25 #include "mount.h"
26 
27 /**
28  * generic_fillattr - Fill in the basic attributes from the inode struct
29  * @mnt_userns:	user namespace of the mount the inode was found from
30  * @inode:	Inode to use as the source
31  * @stat:	Where to fill in the attributes
32  *
33  * Fill in the basic attributes in the kstat structure from data that's to be
34  * found on the VFS inode structure.  This is the default if no getattr inode
35  * operation is supplied.
36  *
37  * If the inode has been found through an idmapped mount the user namespace of
38  * the vfsmount must be passed through @mnt_userns. This function will then
39  * take care to map the inode according to @mnt_userns before filling in the
40  * uid and gid filds. On non-idmapped mounts or if permission checking is to be
41  * performed on the raw inode simply passs init_user_ns.
42  */
43 void generic_fillattr(struct user_namespace *mnt_userns, struct inode *inode,
44 		      struct kstat *stat)
45 {
46 	stat->dev = inode->i_sb->s_dev;
47 	stat->ino = inode->i_ino;
48 	stat->mode = inode->i_mode;
49 	stat->nlink = inode->i_nlink;
50 	stat->uid = i_uid_into_mnt(mnt_userns, inode);
51 	stat->gid = i_gid_into_mnt(mnt_userns, inode);
52 	stat->rdev = inode->i_rdev;
53 	stat->size = i_size_read(inode);
54 	stat->atime = inode->i_atime;
55 	stat->mtime = inode->i_mtime;
56 	stat->ctime = inode->i_ctime;
57 	stat->blksize = i_blocksize(inode);
58 	stat->blocks = inode->i_blocks;
59 }
60 EXPORT_SYMBOL(generic_fillattr);
61 
62 /**
63  * vfs_getattr_nosec - getattr without security checks
64  * @path: file to get attributes from
65  * @stat: structure to return attributes in
66  * @request_mask: STATX_xxx flags indicating what the caller wants
67  * @query_flags: Query mode (AT_STATX_SYNC_TYPE)
68  *
69  * Get attributes without calling security_inode_getattr.
70  *
71  * Currently the only caller other than vfs_getattr is internal to the
72  * filehandle lookup code, which uses only the inode number and returns no
73  * attributes to any user.  Any other code probably wants vfs_getattr.
74  */
75 int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
76 		      u32 request_mask, unsigned int query_flags)
77 {
78 	struct user_namespace *mnt_userns;
79 	struct inode *inode = d_backing_inode(path->dentry);
80 
81 	memset(stat, 0, sizeof(*stat));
82 	stat->result_mask |= STATX_BASIC_STATS;
83 	query_flags &= AT_STATX_SYNC_TYPE;
84 
85 	/* allow the fs to override these if it really wants to */
86 	/* SB_NOATIME means filesystem supplies dummy atime value */
87 	if (inode->i_sb->s_flags & SB_NOATIME)
88 		stat->result_mask &= ~STATX_ATIME;
89 
90 	/*
91 	 * Note: If you add another clause to set an attribute flag, please
92 	 * update attributes_mask below.
93 	 */
94 	if (IS_AUTOMOUNT(inode))
95 		stat->attributes |= STATX_ATTR_AUTOMOUNT;
96 
97 	if (IS_DAX(inode))
98 		stat->attributes |= STATX_ATTR_DAX;
99 
100 	stat->attributes_mask |= (STATX_ATTR_AUTOMOUNT |
101 				  STATX_ATTR_DAX);
102 
103 	mnt_userns = mnt_user_ns(path->mnt);
104 	if (inode->i_op->getattr)
105 		return inode->i_op->getattr(mnt_userns, path, stat,
106 					    request_mask, query_flags);
107 
108 	generic_fillattr(mnt_userns, inode, stat);
109 	return 0;
110 }
111 EXPORT_SYMBOL(vfs_getattr_nosec);
112 
113 /*
114  * vfs_getattr - Get the enhanced basic attributes of a file
115  * @path: The file of interest
116  * @stat: Where to return the statistics
117  * @request_mask: STATX_xxx flags indicating what the caller wants
118  * @query_flags: Query mode (AT_STATX_SYNC_TYPE)
119  *
120  * Ask the filesystem for a file's attributes.  The caller must indicate in
121  * request_mask and query_flags to indicate what they want.
122  *
123  * If the file is remote, the filesystem can be forced to update the attributes
124  * from the backing store by passing AT_STATX_FORCE_SYNC in query_flags or can
125  * suppress the update by passing AT_STATX_DONT_SYNC.
126  *
127  * Bits must have been set in request_mask to indicate which attributes the
128  * caller wants retrieving.  Any such attribute not requested may be returned
129  * anyway, but the value may be approximate, and, if remote, may not have been
130  * synchronised with the server.
131  *
132  * 0 will be returned on success, and a -ve error code if unsuccessful.
133  */
134 int vfs_getattr(const struct path *path, struct kstat *stat,
135 		u32 request_mask, unsigned int query_flags)
136 {
137 	int retval;
138 
139 	retval = security_inode_getattr(path);
140 	if (retval)
141 		return retval;
142 	return vfs_getattr_nosec(path, stat, request_mask, query_flags);
143 }
144 EXPORT_SYMBOL(vfs_getattr);
145 
146 /**
147  * vfs_fstat - Get the basic attributes by file descriptor
148  * @fd: The file descriptor referring to the file of interest
149  * @stat: The result structure to fill in.
150  *
151  * This function is a wrapper around vfs_getattr().  The main difference is
152  * that it uses a file descriptor to determine the file location.
153  *
154  * 0 will be returned on success, and a -ve error code if unsuccessful.
155  */
156 int vfs_fstat(int fd, struct kstat *stat)
157 {
158 	struct fd f;
159 	int error;
160 
161 	f = fdget_raw(fd);
162 	if (!f.file)
163 		return -EBADF;
164 	error = vfs_getattr(&f.file->f_path, stat, STATX_BASIC_STATS, 0);
165 	fdput(f);
166 	return error;
167 }
168 
169 /**
170  * vfs_statx - Get basic and extra attributes by filename
171  * @dfd: A file descriptor representing the base dir for a relative filename
172  * @filename: The name of the file of interest
173  * @flags: Flags to control the query
174  * @stat: The result structure to fill in.
175  * @request_mask: STATX_xxx flags indicating what the caller wants
176  *
177  * This function is a wrapper around vfs_getattr().  The main difference is
178  * that it uses a filename and base directory to determine the file location.
179  * Additionally, the use of AT_SYMLINK_NOFOLLOW in flags will prevent a symlink
180  * at the given name from being referenced.
181  *
182  * 0 will be returned on success, and a -ve error code if unsuccessful.
183  */
184 static int vfs_statx(int dfd, const char __user *filename, int flags,
185 	      struct kstat *stat, u32 request_mask)
186 {
187 	struct path path;
188 	unsigned lookup_flags = 0;
189 	int error;
190 
191 	if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | AT_EMPTY_PATH |
192 		      AT_STATX_SYNC_TYPE))
193 		return -EINVAL;
194 
195 	if (!(flags & AT_SYMLINK_NOFOLLOW))
196 		lookup_flags |= LOOKUP_FOLLOW;
197 	if (!(flags & AT_NO_AUTOMOUNT))
198 		lookup_flags |= LOOKUP_AUTOMOUNT;
199 	if (flags & AT_EMPTY_PATH)
200 		lookup_flags |= LOOKUP_EMPTY;
201 
202 retry:
203 	error = user_path_at(dfd, filename, lookup_flags, &path);
204 	if (error)
205 		goto out;
206 
207 	error = vfs_getattr(&path, stat, request_mask, flags);
208 	stat->mnt_id = real_mount(path.mnt)->mnt_id;
209 	stat->result_mask |= STATX_MNT_ID;
210 	if (path.mnt->mnt_root == path.dentry)
211 		stat->attributes |= STATX_ATTR_MOUNT_ROOT;
212 	stat->attributes_mask |= STATX_ATTR_MOUNT_ROOT;
213 	path_put(&path);
214 	if (retry_estale(error, lookup_flags)) {
215 		lookup_flags |= LOOKUP_REVAL;
216 		goto retry;
217 	}
218 out:
219 	return error;
220 }
221 
222 int vfs_fstatat(int dfd, const char __user *filename,
223 			      struct kstat *stat, int flags)
224 {
225 	return vfs_statx(dfd, filename, flags | AT_NO_AUTOMOUNT,
226 			 stat, STATX_BASIC_STATS);
227 }
228 
229 #ifdef __ARCH_WANT_OLD_STAT
230 
231 /*
232  * For backward compatibility?  Maybe this should be moved
233  * into arch/i386 instead?
234  */
235 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
236 {
237 	static int warncount = 5;
238 	struct __old_kernel_stat tmp;
239 
240 	if (warncount > 0) {
241 		warncount--;
242 		printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
243 			current->comm);
244 	} else if (warncount < 0) {
245 		/* it's laughable, but... */
246 		warncount = 0;
247 	}
248 
249 	memset(&tmp, 0, sizeof(struct __old_kernel_stat));
250 	tmp.st_dev = old_encode_dev(stat->dev);
251 	tmp.st_ino = stat->ino;
252 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
253 		return -EOVERFLOW;
254 	tmp.st_mode = stat->mode;
255 	tmp.st_nlink = stat->nlink;
256 	if (tmp.st_nlink != stat->nlink)
257 		return -EOVERFLOW;
258 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
259 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
260 	tmp.st_rdev = old_encode_dev(stat->rdev);
261 #if BITS_PER_LONG == 32
262 	if (stat->size > MAX_NON_LFS)
263 		return -EOVERFLOW;
264 #endif
265 	tmp.st_size = stat->size;
266 	tmp.st_atime = stat->atime.tv_sec;
267 	tmp.st_mtime = stat->mtime.tv_sec;
268 	tmp.st_ctime = stat->ctime.tv_sec;
269 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
270 }
271 
272 SYSCALL_DEFINE2(stat, const char __user *, filename,
273 		struct __old_kernel_stat __user *, statbuf)
274 {
275 	struct kstat stat;
276 	int error;
277 
278 	error = vfs_stat(filename, &stat);
279 	if (error)
280 		return error;
281 
282 	return cp_old_stat(&stat, statbuf);
283 }
284 
285 SYSCALL_DEFINE2(lstat, const char __user *, filename,
286 		struct __old_kernel_stat __user *, statbuf)
287 {
288 	struct kstat stat;
289 	int error;
290 
291 	error = vfs_lstat(filename, &stat);
292 	if (error)
293 		return error;
294 
295 	return cp_old_stat(&stat, statbuf);
296 }
297 
298 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
299 {
300 	struct kstat stat;
301 	int error = vfs_fstat(fd, &stat);
302 
303 	if (!error)
304 		error = cp_old_stat(&stat, statbuf);
305 
306 	return error;
307 }
308 
309 #endif /* __ARCH_WANT_OLD_STAT */
310 
311 #ifdef __ARCH_WANT_NEW_STAT
312 
313 #if BITS_PER_LONG == 32
314 #  define choose_32_64(a,b) a
315 #else
316 #  define choose_32_64(a,b) b
317 #endif
318 
319 #define valid_dev(x)  choose_32_64(old_valid_dev(x),true)
320 #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
321 
322 #ifndef INIT_STRUCT_STAT_PADDING
323 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
324 #endif
325 
326 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
327 {
328 	struct stat tmp;
329 
330 	if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
331 		return -EOVERFLOW;
332 #if BITS_PER_LONG == 32
333 	if (stat->size > MAX_NON_LFS)
334 		return -EOVERFLOW;
335 #endif
336 
337 	INIT_STRUCT_STAT_PADDING(tmp);
338 	tmp.st_dev = encode_dev(stat->dev);
339 	tmp.st_ino = stat->ino;
340 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
341 		return -EOVERFLOW;
342 	tmp.st_mode = stat->mode;
343 	tmp.st_nlink = stat->nlink;
344 	if (tmp.st_nlink != stat->nlink)
345 		return -EOVERFLOW;
346 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
347 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
348 	tmp.st_rdev = encode_dev(stat->rdev);
349 	tmp.st_size = stat->size;
350 	tmp.st_atime = stat->atime.tv_sec;
351 	tmp.st_mtime = stat->mtime.tv_sec;
352 	tmp.st_ctime = stat->ctime.tv_sec;
353 #ifdef STAT_HAVE_NSEC
354 	tmp.st_atime_nsec = stat->atime.tv_nsec;
355 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
356 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
357 #endif
358 	tmp.st_blocks = stat->blocks;
359 	tmp.st_blksize = stat->blksize;
360 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
361 }
362 
363 SYSCALL_DEFINE2(newstat, const char __user *, filename,
364 		struct stat __user *, statbuf)
365 {
366 	struct kstat stat;
367 	int error = vfs_stat(filename, &stat);
368 
369 	if (error)
370 		return error;
371 	return cp_new_stat(&stat, statbuf);
372 }
373 
374 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
375 		struct stat __user *, statbuf)
376 {
377 	struct kstat stat;
378 	int error;
379 
380 	error = vfs_lstat(filename, &stat);
381 	if (error)
382 		return error;
383 
384 	return cp_new_stat(&stat, statbuf);
385 }
386 
387 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
388 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
389 		struct stat __user *, statbuf, int, flag)
390 {
391 	struct kstat stat;
392 	int error;
393 
394 	error = vfs_fstatat(dfd, filename, &stat, flag);
395 	if (error)
396 		return error;
397 	return cp_new_stat(&stat, statbuf);
398 }
399 #endif
400 
401 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
402 {
403 	struct kstat stat;
404 	int error = vfs_fstat(fd, &stat);
405 
406 	if (!error)
407 		error = cp_new_stat(&stat, statbuf);
408 
409 	return error;
410 }
411 #endif
412 
413 static int do_readlinkat(int dfd, const char __user *pathname,
414 			 char __user *buf, int bufsiz)
415 {
416 	struct path path;
417 	int error;
418 	int empty = 0;
419 	unsigned int lookup_flags = LOOKUP_EMPTY;
420 
421 	if (bufsiz <= 0)
422 		return -EINVAL;
423 
424 retry:
425 	error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
426 	if (!error) {
427 		struct inode *inode = d_backing_inode(path.dentry);
428 
429 		error = empty ? -ENOENT : -EINVAL;
430 		/*
431 		 * AFS mountpoints allow readlink(2) but are not symlinks
432 		 */
433 		if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
434 			error = security_inode_readlink(path.dentry);
435 			if (!error) {
436 				touch_atime(&path);
437 				error = vfs_readlink(path.dentry, buf, bufsiz);
438 			}
439 		}
440 		path_put(&path);
441 		if (retry_estale(error, lookup_flags)) {
442 			lookup_flags |= LOOKUP_REVAL;
443 			goto retry;
444 		}
445 	}
446 	return error;
447 }
448 
449 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
450 		char __user *, buf, int, bufsiz)
451 {
452 	return do_readlinkat(dfd, pathname, buf, bufsiz);
453 }
454 
455 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
456 		int, bufsiz)
457 {
458 	return do_readlinkat(AT_FDCWD, path, buf, bufsiz);
459 }
460 
461 
462 /* ---------- LFS-64 ----------- */
463 #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
464 
465 #ifndef INIT_STRUCT_STAT64_PADDING
466 #  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
467 #endif
468 
469 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
470 {
471 	struct stat64 tmp;
472 
473 	INIT_STRUCT_STAT64_PADDING(tmp);
474 #ifdef CONFIG_MIPS
475 	/* mips has weird padding, so we don't get 64 bits there */
476 	tmp.st_dev = new_encode_dev(stat->dev);
477 	tmp.st_rdev = new_encode_dev(stat->rdev);
478 #else
479 	tmp.st_dev = huge_encode_dev(stat->dev);
480 	tmp.st_rdev = huge_encode_dev(stat->rdev);
481 #endif
482 	tmp.st_ino = stat->ino;
483 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
484 		return -EOVERFLOW;
485 #ifdef STAT64_HAS_BROKEN_ST_INO
486 	tmp.__st_ino = stat->ino;
487 #endif
488 	tmp.st_mode = stat->mode;
489 	tmp.st_nlink = stat->nlink;
490 	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
491 	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
492 	tmp.st_atime = stat->atime.tv_sec;
493 	tmp.st_atime_nsec = stat->atime.tv_nsec;
494 	tmp.st_mtime = stat->mtime.tv_sec;
495 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
496 	tmp.st_ctime = stat->ctime.tv_sec;
497 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
498 	tmp.st_size = stat->size;
499 	tmp.st_blocks = stat->blocks;
500 	tmp.st_blksize = stat->blksize;
501 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
502 }
503 
504 SYSCALL_DEFINE2(stat64, const char __user *, filename,
505 		struct stat64 __user *, statbuf)
506 {
507 	struct kstat stat;
508 	int error = vfs_stat(filename, &stat);
509 
510 	if (!error)
511 		error = cp_new_stat64(&stat, statbuf);
512 
513 	return error;
514 }
515 
516 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
517 		struct stat64 __user *, statbuf)
518 {
519 	struct kstat stat;
520 	int error = vfs_lstat(filename, &stat);
521 
522 	if (!error)
523 		error = cp_new_stat64(&stat, statbuf);
524 
525 	return error;
526 }
527 
528 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
529 {
530 	struct kstat stat;
531 	int error = vfs_fstat(fd, &stat);
532 
533 	if (!error)
534 		error = cp_new_stat64(&stat, statbuf);
535 
536 	return error;
537 }
538 
539 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
540 		struct stat64 __user *, statbuf, int, flag)
541 {
542 	struct kstat stat;
543 	int error;
544 
545 	error = vfs_fstatat(dfd, filename, &stat, flag);
546 	if (error)
547 		return error;
548 	return cp_new_stat64(&stat, statbuf);
549 }
550 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
551 
552 static noinline_for_stack int
553 cp_statx(const struct kstat *stat, struct statx __user *buffer)
554 {
555 	struct statx tmp;
556 
557 	memset(&tmp, 0, sizeof(tmp));
558 
559 	tmp.stx_mask = stat->result_mask;
560 	tmp.stx_blksize = stat->blksize;
561 	tmp.stx_attributes = stat->attributes;
562 	tmp.stx_nlink = stat->nlink;
563 	tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid);
564 	tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid);
565 	tmp.stx_mode = stat->mode;
566 	tmp.stx_ino = stat->ino;
567 	tmp.stx_size = stat->size;
568 	tmp.stx_blocks = stat->blocks;
569 	tmp.stx_attributes_mask = stat->attributes_mask;
570 	tmp.stx_atime.tv_sec = stat->atime.tv_sec;
571 	tmp.stx_atime.tv_nsec = stat->atime.tv_nsec;
572 	tmp.stx_btime.tv_sec = stat->btime.tv_sec;
573 	tmp.stx_btime.tv_nsec = stat->btime.tv_nsec;
574 	tmp.stx_ctime.tv_sec = stat->ctime.tv_sec;
575 	tmp.stx_ctime.tv_nsec = stat->ctime.tv_nsec;
576 	tmp.stx_mtime.tv_sec = stat->mtime.tv_sec;
577 	tmp.stx_mtime.tv_nsec = stat->mtime.tv_nsec;
578 	tmp.stx_rdev_major = MAJOR(stat->rdev);
579 	tmp.stx_rdev_minor = MINOR(stat->rdev);
580 	tmp.stx_dev_major = MAJOR(stat->dev);
581 	tmp.stx_dev_minor = MINOR(stat->dev);
582 	tmp.stx_mnt_id = stat->mnt_id;
583 
584 	return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
585 }
586 
587 int do_statx(int dfd, const char __user *filename, unsigned flags,
588 	     unsigned int mask, struct statx __user *buffer)
589 {
590 	struct kstat stat;
591 	int error;
592 
593 	if (mask & STATX__RESERVED)
594 		return -EINVAL;
595 	if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
596 		return -EINVAL;
597 
598 	error = vfs_statx(dfd, filename, flags, &stat, mask);
599 	if (error)
600 		return error;
601 
602 	return cp_statx(&stat, buffer);
603 }
604 
605 /**
606  * sys_statx - System call to get enhanced stats
607  * @dfd: Base directory to pathwalk from *or* fd to stat.
608  * @filename: File to stat or "" with AT_EMPTY_PATH
609  * @flags: AT_* flags to control pathwalk.
610  * @mask: Parts of statx struct actually required.
611  * @buffer: Result buffer.
612  *
613  * Note that fstat() can be emulated by setting dfd to the fd of interest,
614  * supplying "" as the filename and setting AT_EMPTY_PATH in the flags.
615  */
616 SYSCALL_DEFINE5(statx,
617 		int, dfd, const char __user *, filename, unsigned, flags,
618 		unsigned int, mask,
619 		struct statx __user *, buffer)
620 {
621 	return do_statx(dfd, filename, flags, mask, buffer);
622 }
623 
624 #ifdef CONFIG_COMPAT
625 static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
626 {
627 	struct compat_stat tmp;
628 
629 	if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
630 		return -EOVERFLOW;
631 
632 	memset(&tmp, 0, sizeof(tmp));
633 	tmp.st_dev = old_encode_dev(stat->dev);
634 	tmp.st_ino = stat->ino;
635 	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
636 		return -EOVERFLOW;
637 	tmp.st_mode = stat->mode;
638 	tmp.st_nlink = stat->nlink;
639 	if (tmp.st_nlink != stat->nlink)
640 		return -EOVERFLOW;
641 	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
642 	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
643 	tmp.st_rdev = old_encode_dev(stat->rdev);
644 	if ((u64) stat->size > MAX_NON_LFS)
645 		return -EOVERFLOW;
646 	tmp.st_size = stat->size;
647 	tmp.st_atime = stat->atime.tv_sec;
648 	tmp.st_atime_nsec = stat->atime.tv_nsec;
649 	tmp.st_mtime = stat->mtime.tv_sec;
650 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
651 	tmp.st_ctime = stat->ctime.tv_sec;
652 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
653 	tmp.st_blocks = stat->blocks;
654 	tmp.st_blksize = stat->blksize;
655 	return copy_to_user(ubuf, &tmp, sizeof(tmp)) ? -EFAULT : 0;
656 }
657 
658 COMPAT_SYSCALL_DEFINE2(newstat, const char __user *, filename,
659 		       struct compat_stat __user *, statbuf)
660 {
661 	struct kstat stat;
662 	int error;
663 
664 	error = vfs_stat(filename, &stat);
665 	if (error)
666 		return error;
667 	return cp_compat_stat(&stat, statbuf);
668 }
669 
670 COMPAT_SYSCALL_DEFINE2(newlstat, const char __user *, filename,
671 		       struct compat_stat __user *, statbuf)
672 {
673 	struct kstat stat;
674 	int error;
675 
676 	error = vfs_lstat(filename, &stat);
677 	if (error)
678 		return error;
679 	return cp_compat_stat(&stat, statbuf);
680 }
681 
682 #ifndef __ARCH_WANT_STAT64
683 COMPAT_SYSCALL_DEFINE4(newfstatat, unsigned int, dfd,
684 		       const char __user *, filename,
685 		       struct compat_stat __user *, statbuf, int, flag)
686 {
687 	struct kstat stat;
688 	int error;
689 
690 	error = vfs_fstatat(dfd, filename, &stat, flag);
691 	if (error)
692 		return error;
693 	return cp_compat_stat(&stat, statbuf);
694 }
695 #endif
696 
697 COMPAT_SYSCALL_DEFINE2(newfstat, unsigned int, fd,
698 		       struct compat_stat __user *, statbuf)
699 {
700 	struct kstat stat;
701 	int error = vfs_fstat(fd, &stat);
702 
703 	if (!error)
704 		error = cp_compat_stat(&stat, statbuf);
705 	return error;
706 }
707 #endif
708 
709 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
710 void __inode_add_bytes(struct inode *inode, loff_t bytes)
711 {
712 	inode->i_blocks += bytes >> 9;
713 	bytes &= 511;
714 	inode->i_bytes += bytes;
715 	if (inode->i_bytes >= 512) {
716 		inode->i_blocks++;
717 		inode->i_bytes -= 512;
718 	}
719 }
720 EXPORT_SYMBOL(__inode_add_bytes);
721 
722 void inode_add_bytes(struct inode *inode, loff_t bytes)
723 {
724 	spin_lock(&inode->i_lock);
725 	__inode_add_bytes(inode, bytes);
726 	spin_unlock(&inode->i_lock);
727 }
728 
729 EXPORT_SYMBOL(inode_add_bytes);
730 
731 void __inode_sub_bytes(struct inode *inode, loff_t bytes)
732 {
733 	inode->i_blocks -= bytes >> 9;
734 	bytes &= 511;
735 	if (inode->i_bytes < bytes) {
736 		inode->i_blocks--;
737 		inode->i_bytes += 512;
738 	}
739 	inode->i_bytes -= bytes;
740 }
741 
742 EXPORT_SYMBOL(__inode_sub_bytes);
743 
744 void inode_sub_bytes(struct inode *inode, loff_t bytes)
745 {
746 	spin_lock(&inode->i_lock);
747 	__inode_sub_bytes(inode, bytes);
748 	spin_unlock(&inode->i_lock);
749 }
750 
751 EXPORT_SYMBOL(inode_sub_bytes);
752 
753 loff_t inode_get_bytes(struct inode *inode)
754 {
755 	loff_t ret;
756 
757 	spin_lock(&inode->i_lock);
758 	ret = __inode_get_bytes(inode);
759 	spin_unlock(&inode->i_lock);
760 	return ret;
761 }
762 
763 EXPORT_SYMBOL(inode_get_bytes);
764 
765 void inode_set_bytes(struct inode *inode, loff_t bytes)
766 {
767 	/* Caller is here responsible for sufficient locking
768 	 * (ie. inode->i_lock) */
769 	inode->i_blocks = bytes >> 9;
770 	inode->i_bytes = bytes & 511;
771 }
772 
773 EXPORT_SYMBOL(inode_set_bytes);
774