Introduce man pages for file_getattr() and file_setattr()

Date: 2026-10-21 16:10:04+0200
From: Andrey Albershteyn <[email protected]>

Add manual page for file_getattr().

Link https://lore.kernel.org/all/[email protected]/ open here

Reviewed-by Alejandro Colomar <[email protected]>

Signed-off-by Andrey Albershteyn <[email protected]>

---
 man/man2/file_getattr.2 | 252 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 252 insertions(+)
 create mode 100644 man/man2/file_getattr.2

man/man2/file_getattr.2 new file +252 -0

new file mode 100644
index 000000000000..9963eeaa7caf
@@ -0,0 +1,252 @@
+.\" Copyright, the authors of the Linux man-pages project
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH file_getattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+file_getattr \- get filesystem file attributes
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fcntl.h>" "      /* " AT_* " constants */"
+.BR "#include <linux/fs.h>" "         /* " FS_XFLAG_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.B long syscall(SYS_file_getattr,
+.BI "               int " dirfd ", const char *" path ,
+.BI "               struct file_attr *" fattr ", size_t " size ,
+.BI "               unsigned int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR file_getattr ()
+system call retrieves filesystem file attributes
+of the file
+specified by path.
+.P
+The
+.I dirfd
+and
+.I path
+arguments behave in the same way as in
+.BR openat (2),
+with the difference that
+.I path
+can be NULL meaning an empty string.
+.P
+The
+.I fattr
+argument is a pointer to a
+.I file_attr
+structure.
+This structure will be filled with file attributes.
+This structure is described in
+.BR file_attr (2type).
+.P
+The
+.I size
+argument specifies the size of the structure pointed to by
+.IR fattr .
+The size indicates the version of the structure in use,
+and should always be specified as
+.IR sizeof(struct file_attr) .
+.P
+The
+.I flags
+argument contains a bitwise OR of zero or more of the following constants:
+.TP
+.B AT_EMPTY_PATH
+If
+.I path
+is an empty string,
+operate on the file referred to by
+.IR dirfd .
+In this case,
+.I dirfd
+can refer to any type of file,
+not just a directory.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I path
+is a symbolic link,
+do not dereference it;
+instead,
+get attributes of the symbolic link inode itself.
+.SH RETURN VALUE
+On success,
+zero is returned.
+On error,
+\-1 is returned,
+and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B E2BIG
+.I size
+is too big (larger than
+.BR PAGE_SIZE ).
+.TP
+.B EACCES
+Search permission is denied for one of the directories
+in the path prefix of
+.IR path .
+.TP
+.B EBADF
+.I path
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EBADF
+.I path
+is an empty string,
+.B AT_EMPTY_PATH
+was specified,
+but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I path
+or
+.I fattr
+is an invalid pointer.
+.TP
+.B EINVAL
+Unknown flags specified in
+.IR flags .
+.TP
+.B EINVAL
+.I size
+is smaller than
+.BR FILE_ATTR_SIZE_VER0 .
+.TP
+.B ELOOP
+Too many symbolic links encountered while resolving
+.IR path .
+.TP
+.B ENAMETOOLONG
+.I path
+is too long.
+.TP
+.B ENOENT
+A component of
+.I path
+does not exist.
+.TP
+.B ENOENT
+.I path
+is an empty string and
+.B AT_EMPTY_PATH
+was not specified in
+.IR flags .
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of the path prefix of
+.I path
+is not a directory.
+.TP
+.B ENOTDIR
+.I path
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EOPNOTSUPP
+The filesystem does not support getting attributes on this type of inode.
+.SH HISTORY
+Linux 6.17
+.SH NOTES
+This system call is designed to be extensible.
+The
+.I size
+argument allows user-space applications to indicate
+which version of the
+.I file_attr
+structure they are using,
+enabling the kernel to support both old and new versions
+of the structure simultaneously.
+.P
+If
+.I size
+is smaller than the structure size the kernel expects,
+only the fields that fit within
+.I size
+will be filled in.
+If
+.I size
+is larger than the kernel's structure size,
+the extra bytes are zeroed.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR file_getattr ()
+to retrieve and display file attributes.
+.P
+.in +4n
+.\" SRC BEGIN (file_getattr.c)
+.EX
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <linux/fs.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+#ifndef SYS_file_getattr
+#define SYS_file_getattr 467
+#endif
+\&
+int
+main(int argc, char *argv[])
+{
+    struct file_attr fa;
+    long ret;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <filename>\[rs]n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    ret = syscall(SYS_file_getattr, AT_FDCWD, argv[1], &fa,
+                  sizeof(fa), 0);
+    if (ret == \-1) {
+        perror("file_getattr");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("File attributes:\[rs]n");
+    printf("  xflags:     0x%w64x\[rs]n", fa.fa_xflags);
+    printf("  extsize:    %w32u\[rs]n", fa.fa_extsize);
+    printf("  nextents:   %w32u\[rs]n", fa.fa_nextents);
+    printf("  projid:     %w32u\[rs]n", fa.fa_projid);
+    printf("  cowextsize: %w32u\[rs]n", fa.fa_cowextsize);
+\&
+    /*
+     * Try setting NODUMP flag with chattr +d ./foo to see
+     * the difference.
+     */
+    if (fa.fa_xflags & FS_XFLAG_NODUMP)
+        printf("  NODUMP flag is set\[rs]n");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR file_setattr (2),
+.BR file_attr (2type),
+.BR ioctl (2),
+.BR ioctl_fs (2),
+.BR openat (2),
+.BR ioctl_xfs_fssetxattr (2)

Signature · 1 line

2.56.0

Date: 2026-10-21 16:10:05+0200
From: Andrey Albershteyn <[email protected]>

Add manual pages for file_setattr() syscall.

Link https://lore.kernel.org/all/[email protected]/ open here

Signed-off-by Andrey Albershteyn <[email protected]>

---
 man/man2/file_setattr.2 | 183 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 183 insertions(+)
 create mode 100644 man/man2/file_setattr.2

man/man2/file_setattr.2 new file +183 -0

new file mode 100644
index 000000000000..b11c9ff9277f
@@ -0,0 +1,183 @@
+.\" Copyright, the authors of the Linux man-pages project
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH file_setattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+file_setattr \- set filesystem file attributes
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fcntl.h>" "      /* Definition of " AT_* " constants */"
+.BR "#include <linux/fs.h>" "         /* Definition of " FS_XFLAG_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.B long syscall(SYS_file_setattr,
+.BI "               int " dirfd ", const char *" path ,
+.BI "               const struct file_attr *" fattr ", size_t " size ,
+.BI "               unsigned int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR file_setattr ()
+system call sets filesystem file attributes
+on the file specified by path.
+.P
+The
+.IR dirfd ,
+.IR path ,
+.IR size ,
+and
+.I flags
+arguments behave in the same way as in
+.BR file_getattr (2).
+The
+.IR fattr ,
+is read-only argument with
+file attributes to set.
+User-space applications should use
+.BR file_getattr (2)
+to initialize
+.I fattr
+argument beforehand.
+.SH RETURN VALUE
+On success,
+zero is returned.
+On error,
+\-1 is returned,
+and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The errors are the same as returned by
+.BR file_getattr (2)
+with the addition of following ones:
+.TP
+.B E2BIG
+.I size
+indicates a version which the kernel doesn't support
+(the size is larger than the kernel expects)
+and new fields are non-zero.
+.TP
+.B EINVAL
+Invalid combination of parameters provided in
+.I fattr
+for this type of file or filesystem.
+.TP
+.B EPERM
+The caller does not have the necessary permissions
+to change the file attributes.
+.TP
+.B EROFS
+The file is on a read-only filesystem.
+.SH HISTORY
+Linux 6.17
+.SH NOTES
+This system call is designed to be extensible.
+The
+.I size
+argument allows user-space applications to indicate
+which version of the
+.I file_attr
+structure they are using,
+enabling the kernel to support both old and new versions
+of the structure simultaneously.
+.P
+If
+.I size
+is smaller than the structure size the kernel expects,
+the kernel treats the missing fields as having zero values
+(which is a no-op).
+If
+.I size
+is larger than expected,
+the kernel checks that all unknown (to the kernel) fields are zero;
+if not,
+the call fails with
+.BR E2BIG .
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR file_setattr ()
+to set the
+.B FS_XFLAG_NODUMP
+flag on a file.
+.P
+.in +4n
+.\" SRC BEGIN (file_setattr.c)
+.EX
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <linux/fs.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+#ifndef SYS_file_getattr
+#define SYS_file_getattr 467
+#endif
+\&
+#ifndef SYS_file_setattr
+#define SYS_file_setattr 468
+#endif
+\&
+int
+main(int argc, char *argv[])
+{
+    struct file_attr fa;
+    int dfd;
+    long ret;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <filename>\[rs]n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    dfd = open(argv[1], O_RDONLY);
+    if (dfd == \-1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    ret = syscall(SYS_file_getattr, dfd, "", &fa, sizeof(fa),
+                  AT_EMPTY_PATH);
+    if (ret == \-1) {
+        perror("file_getattr");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Current flags: 0x%w64x\[rs]n", fa.fa_xflags);
+\&
+    fa.fa_xflags |= FS_XFLAG_NODUMP;
+\&
+    ret = syscall(SYS_file_setattr, dfd, "", &fa, sizeof(fa),
+                  AT_EMPTY_PATH);
+    if (ret == \-1) {
+        perror("file_setattr");
+        exit(EXIT_FAILURE);
+    }
+\&
+    ret = syscall(SYS_file_getattr, dfd, "", &fa, sizeof(fa),
+                  AT_EMPTY_PATH);
+    if (ret == \-1) {
+        perror("file_getattr");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (fa.fa_xflags & FS_XFLAG_NODUMP)
+        printf("flags 0x%w64x (NODUMP flag is set)\[rs]n", fa.fa_xflags);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR file_getattr (2),
+.BR ioctl (2),
+.BR ioctl_fs (2),
+.BR openat (2),
+.BR file_attr (2type),
+.BR path_resolution (7),
+.BR ioctl_xfs_fssetxattr (2)

Signature · 1 line

2.56.0