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.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH mount_attr 2type 2025-09-21 "Linux man-pages (unreleased)"
.SH NAME
mount_attr \- what mount properties to set and clear
.SH LIBRARY
Linux kernel headers
.SH SYNOPSIS
.EX
.B #include <sys/mount.h>
.P
.B struct mount_attr {
.BR " u64 attr_set;" " /* Mount properties to set */"
.BR " u64 attr_clr;" " /* Mount properties to clear */"
.BR " u64 propagation;" " /* Mount propagation type */"
.BR " u64 userns_fd;" " /* User namespace file descriptor */"
/* ...\& */
.B };
.EE
.SH DESCRIPTION
Specifies which mount properties should be changed with
.BR mount_setattr (2).
.P
The fields are as follows:
.TP
.I .attr_set
This field specifies which
.BI MOUNT_ATTR_ *
attribute flags to set.
.TP
.I .attr_clr
This field specifies which
.BI MOUNT_ATTR_ *
attribute flags to clear.
.TP
.I .propagation
This field specifies what mount propagation will be applied.
The valid values of this field are the same propagation types described in
.BR mount_namespaces (7).
.TP
.I .userns_fd
This field specifies a file descriptor that indicates which user namespace to
use as a reference for ID-mapped mounts with
.BR MOUNT_ATTR_IDMAP .
.SH STANDARDS
Linux.
.SH HISTORY
Linux 5.12.
.\" commit 2a1867219c7b27f928e2545782b86daaf9ad50bd
glibc 2.36.
.P
Extra fields may be appended to the structure,
with a zero value in a new field resulting in
the kernel behaving as though that extension field was not present.
Therefore, a user
.I must
zero-fill this structure on initialization.
.SH SEE ALSO
.BR mount_setattr (2)
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