tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
fs: introduce file_getattr and file_setattr syscalls
Introduce file_getattr() and file_setattr() syscalls to manipulate inode
extended attributes. The syscalls takes pair of file descriptor and
pathname. Then it operates on inode opened accroding to openat()
semantics. The struct file_attr is passed to obtain/change extended
attributes.
This is an alternative to FS_IOC_FSSETXATTR ioctl with a difference
that file don't need to be open as we can reference it with a path
instead of fd. By having this we can manipulated inode extended
attributes not only on regular files but also on special ones. This
is not possible with FS_IOC_FSSETXATTR ioctl as with special files
we can not call ioctl() directly on the filesystem inode using fd.
This patch adds two new syscalls which allows userspace to get/set
extended inode attributes on special files by using parent directory
and a path - *at() like syscall.
CC: linux-api@vger.kernel.org
CC: linux-fsdevel@vger.kernel.org
CC: linux-xfs@vger.kernel.org
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Link: https://lore.kernel.org/20250630-xattrat-syscall-v6-6-c4e3bc35227b@kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
authored by
Andrey Albershteyn
and committed by
Christian Brauner
be7efb2d
276e136b
+218
-1
+2
arch/alpha/kernel/syscalls/syscall.tbl
+2
arch/alpha/kernel/syscalls/syscall.tbl
+2
arch/arm/tools/syscall.tbl
+2
arch/arm/tools/syscall.tbl
+2
arch/arm64/tools/syscall_32.tbl
+2
arch/arm64/tools/syscall_32.tbl
+2
arch/m68k/kernel/syscalls/syscall.tbl
+2
arch/m68k/kernel/syscalls/syscall.tbl
+2
arch/microblaze/kernel/syscalls/syscall.tbl
+2
arch/microblaze/kernel/syscalls/syscall.tbl
+2
arch/mips/kernel/syscalls/syscall_n32.tbl
+2
arch/mips/kernel/syscalls/syscall_n32.tbl
+2
arch/mips/kernel/syscalls/syscall_n64.tbl
+2
arch/mips/kernel/syscalls/syscall_n64.tbl
+2
arch/mips/kernel/syscalls/syscall_o32.tbl
+2
arch/mips/kernel/syscalls/syscall_o32.tbl
+2
arch/parisc/kernel/syscalls/syscall.tbl
+2
arch/parisc/kernel/syscalls/syscall.tbl
+2
arch/powerpc/kernel/syscalls/syscall.tbl
+2
arch/powerpc/kernel/syscalls/syscall.tbl
+2
arch/s390/kernel/syscalls/syscall.tbl
+2
arch/s390/kernel/syscalls/syscall.tbl
···
470
470
465 common listxattrat sys_listxattrat sys_listxattrat
471
471
466 common removexattrat sys_removexattrat sys_removexattrat
472
472
467 common open_tree_attr sys_open_tree_attr sys_open_tree_attr
473
+
468 common file_getattr sys_file_getattr sys_file_getattr
474
+
469 common file_setattr sys_file_setattr sys_file_setattr
+2
arch/sh/kernel/syscalls/syscall.tbl
+2
arch/sh/kernel/syscalls/syscall.tbl
+2
arch/sparc/kernel/syscalls/syscall.tbl
+2
arch/sparc/kernel/syscalls/syscall.tbl
+2
arch/x86/entry/syscalls/syscall_32.tbl
+2
arch/x86/entry/syscalls/syscall_32.tbl
+2
arch/x86/entry/syscalls/syscall_64.tbl
+2
arch/x86/entry/syscalls/syscall_64.tbl
···
391
391
465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr
394
+
468 common file_getattr sys_file_getattr
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+
469 common file_setattr sys_file_setattr
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#
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# Due to a historical design error, certain syscalls are numbered differently
+2
arch/xtensa/kernel/syscalls/syscall.tbl
+2
arch/xtensa/kernel/syscalls/syscall.tbl
+152
fs/file_attr.c
+152
fs/file_attr.c
···
4
4
#include <linux/fscrypt.h>
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#include <linux/fileattr.h>
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#include <linux/export.h>
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+
#include <linux/syscalls.h>
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#include <linux/namei.h>
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+
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#include "internal.h"
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/**
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* fileattr_fill_xflags - initialize fileattr with xflags
···
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}
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EXPORT_SYMBOL(vfs_fileattr_get);
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static void fileattr_to_file_attr(const struct fileattr *fa,
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struct file_attr *fattr)
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{
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__u32 mask = FS_XFLAGS_MASK;
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+
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memset(fattr, 0, sizeof(struct file_attr));
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fattr->fa_xflags = fa->fsx_xflags & mask;
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+
fattr->fa_extsize = fa->fsx_extsize;
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fattr->fa_nextents = fa->fsx_nextents;
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fattr->fa_projid = fa->fsx_projid;
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fattr->fa_cowextsize = fa->fsx_cowextsize;
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}
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+
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/**
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* copy_fsxattr_to_user - copy fsxattr to userspace.
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* @fa: fileattr pointer
···
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return 0;
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}
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EXPORT_SYMBOL(copy_fsxattr_to_user);
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+
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static int file_attr_to_fileattr(const struct file_attr *fattr,
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struct fileattr *fa)
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{
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__u32 mask = FS_XFLAGS_MASK;
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+
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if (fattr->fa_xflags & ~mask)
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return -EINVAL;
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+
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fileattr_fill_xflags(fa, fattr->fa_xflags);
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fa->fsx_xflags &= ~FS_XFLAG_RDONLY_MASK;
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fa->fsx_extsize = fattr->fa_extsize;
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fa->fsx_projid = fattr->fa_projid;
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fa->fsx_cowextsize = fattr->fa_cowextsize;
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+
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return 0;
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+
}
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static int copy_fsxattr_from_user(struct fileattr *fa,
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struct fsxattr __user *ufa)
···
378
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return err;
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}
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EXPORT_SYMBOL(ioctl_fssetxattr);
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+
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+
SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
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struct file_attr __user *, ufattr, size_t, usize,
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unsigned int, at_flags)
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{
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struct path filepath __free(path_put) = {};
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struct filename *name __free(putname) = NULL;
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unsigned int lookup_flags = 0;
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struct file_attr fattr;
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struct fileattr fa;
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int error;
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+
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BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
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BUILD_BUG_ON(sizeof(struct file_attr) != FILE_ATTR_SIZE_LATEST);
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+
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if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
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return -EINVAL;
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+
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if (!(at_flags & AT_SYMLINK_NOFOLLOW))
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lookup_flags |= LOOKUP_FOLLOW;
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+
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if (usize > PAGE_SIZE)
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return -E2BIG;
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+
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if (usize < FILE_ATTR_SIZE_VER0)
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return -EINVAL;
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name = getname_maybe_null(filename, at_flags);
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if (IS_ERR(name))
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return PTR_ERR(name);
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+
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if (!name && dfd >= 0) {
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CLASS(fd, f)(dfd);
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if (fd_empty(f))
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return -EBADF;
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filepath = fd_file(f)->f_path;
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path_get(&filepath);
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} else {
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error = filename_lookup(dfd, name, lookup_flags, &filepath,
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NULL);
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if (error)
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return error;
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}
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+
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error = vfs_fileattr_get(filepath.dentry, &fa);
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if (error)
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return error;
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fileattr_to_file_attr(&fa, &fattr);
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error = copy_struct_to_user(ufattr, usize, &fattr,
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sizeof(struct file_attr), NULL);
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return error;
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+
}
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+
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SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename,
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struct file_attr __user *, ufattr, size_t, usize,
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unsigned int, at_flags)
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{
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struct path filepath __free(path_put) = {};
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struct filename *name __free(putname) = NULL;
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unsigned int lookup_flags = 0;
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struct file_attr fattr;
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struct fileattr fa;
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int error;
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+
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BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
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BUILD_BUG_ON(sizeof(struct file_attr) != FILE_ATTR_SIZE_LATEST);
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+
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if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
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return -EINVAL;
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+
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if (!(at_flags & AT_SYMLINK_NOFOLLOW))
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lookup_flags |= LOOKUP_FOLLOW;
422
+
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if (usize > PAGE_SIZE)
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return -E2BIG;
425
+
426
+
if (usize < FILE_ATTR_SIZE_VER0)
427
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return -EINVAL;
428
+
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error = copy_struct_from_user(&fattr, sizeof(struct file_attr), ufattr,
430
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usize);
431
+
if (error)
432
+
return error;
433
+
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+
error = file_attr_to_fileattr(&fattr, &fa);
435
+
if (error)
436
+
return error;
437
+
438
+
name = getname_maybe_null(filename, at_flags);
439
+
if (IS_ERR(name))
440
+
return PTR_ERR(name);
441
+
442
+
if (!name && dfd >= 0) {
443
+
CLASS(fd, f)(dfd);
444
+
if (fd_empty(f))
445
+
return -EBADF;
446
+
447
+
filepath = fd_file(f)->f_path;
448
+
path_get(&filepath);
449
+
} else {
450
+
error = filename_lookup(dfd, name, lookup_flags, &filepath,
451
+
NULL);
452
+
if (error)
453
+
return error;
454
+
}
455
+
456
+
error = mnt_want_write(filepath.mnt);
457
+
if (!error) {
458
+
error = vfs_fileattr_set(mnt_idmap(filepath.mnt),
459
+
filepath.dentry, &fa);
460
+
mnt_drop_write(filepath.mnt);
461
+
}
462
+
463
+
return error;
464
+
}
+7
include/linux/syscalls.h
+7
include/linux/syscalls.h
···
78
78
struct statmount;
79
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struct mnt_id_req;
80
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struct xattr_args;
81
+
struct file_attr;
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#include <linux/types.h>
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#include <linux/aio_abi.h>
···
372
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asmlinkage long sys_lremovexattr(const char __user *path,
373
372
const char __user *name);
374
373
asmlinkage long sys_fremovexattr(int fd, const char __user *name);
374
+
asmlinkage long sys_file_getattr(int dfd, const char __user *filename,
375
+
struct file_attr __user *attr, size_t usize,
376
+
unsigned int at_flags);
377
+
asmlinkage long sys_file_setattr(int dfd, const char __user *filename,
378
+
struct file_attr __user *attr, size_t usize,
379
+
unsigned int at_flags);
375
380
asmlinkage long sys_getcwd(char __user *buf, unsigned long size);
376
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asmlinkage long sys_eventfd2(unsigned int count, int flags);
377
382
asmlinkage long sys_epoll_create1(int flags);
+7
-1
include/uapi/asm-generic/unistd.h
+7
-1
include/uapi/asm-generic/unistd.h
···
852
852
#define __NR_open_tree_attr 467
853
853
__SYSCALL(__NR_open_tree_attr, sys_open_tree_attr)
854
854
855
+
/* fs/inode.c */
856
+
#define __NR_file_getattr 468
857
+
__SYSCALL(__NR_file_getattr, sys_file_getattr)
858
+
#define __NR_file_setattr 469
859
+
__SYSCALL(__NR_file_setattr, sys_file_setattr)
860
+
855
861
#undef __NR_syscalls
856
-
#define __NR_syscalls 468
862
+
#define __NR_syscalls 470
857
863
858
864
/*
859
865
* 32 bit systems traditionally used different
+18
include/uapi/linux/fs.h
+18
include/uapi/linux/fs.h
···
149
149
};
150
150
151
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/*
152
+
* Variable size structure for file_[sg]et_attr().
153
+
*
154
+
* Note. This is alternative to the structure 'struct fileattr'/'struct fsxattr'.
155
+
* As this structure is passed to/from userspace with its size, this can
156
+
* be versioned based on the size.
157
+
*/
158
+
struct file_attr {
159
+
__u64 fa_xflags; /* xflags field value (get/set) */
160
+
__u32 fa_extsize; /* extsize field value (get/set)*/
161
+
__u32 fa_nextents; /* nextents field value (get) */
162
+
__u32 fa_projid; /* project identifier (get/set) */
163
+
__u32 fa_cowextsize; /* CoW extsize field value (get/set) */
164
+
};
165
+
166
+
#define FILE_ATTR_SIZE_VER0 24
167
+
#define FILE_ATTR_SIZE_LATEST FILE_ATTR_SIZE_VER0
168
+
169
+
/*
152
170
* Flags for the fsx_xflags field
153
171
*/
154
172
#define FS_XFLAG_REALTIME 0x00000001 /* data in realtime volume */