linux-kernel - [PATCH v2 02/11] mount_setattr.2: move mount_attr struct to mount

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Message-Id: <20250807-new-mount-api-v2-2-558a27b8068c@cyphar.com>
Date: Thu, 07 Aug 2025 03:44:36 +1000
From: Aleksa Sarai <cyphar@...har.com>
To: Alejandro Colomar <alx@...nel.org>
Cc: "Michael T. Kerrisk" <mtk.manpages@...il.com>, 
 Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, 
 Askar Safin <safinaskar@...omail.com>, 
 "G. Branden Robinson" <g.branden.robinson@...il.com>, 
 linux-man@...r.kernel.org, linux-api@...r.kernel.org, 
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
 David Howells <dhowells@...hat.com>, Christian Brauner <brauner@...nel.org>, 
 Aleksa Sarai <cyphar@...har.com>
Subject: [PATCH v2 02/11] mount_setattr.2: move mount_attr struct to
 mount_attr.2type

As with open_how(2type), it makes sense to move this to a separate man
page.  In addition, future man pages added in this patchset will want to
reference mount_attr(2type).

Signed-off-by: Aleksa Sarai <cyphar@...har.com>
---
 man/man2/mount_setattr.2      | 17 ++++---------
 man/man2type/mount_attr.2type | 58 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 12 deletions(-)

diff --git a/man/man2/mount_setattr.2 b/man/man2/mount_setattr.2
index c96f0657f046..d44fafc93a20 100644
--- a/man/man2/mount_setattr.2
+++ b/man/man2/mount_setattr.2
@@ -114,18 +114,11 @@ .SH DESCRIPTION
 .I attr
 argument of
 .BR mount_setattr ()
-is a structure of the following form:
-.P
-.in +4n
-.EX
-struct mount_attr {
-    __u64 attr_set;     /* Mount properties to set */
-    __u64 attr_clr;     /* Mount properties to clear */
-    __u64 propagation;  /* Mount propagation type */
-    __u64 userns_fd;    /* User namespace file descriptor */
-};
-.EE
-.in
+is a pointer to a
+.I mount_attr
+structure,
+described in
+.BR mount_attr (2type).
 .P
 The
 .I attr_set
diff --git a/man/man2type/mount_attr.2type b/man/man2type/mount_attr.2type
new file mode 100644
index 000000000000..b7a3ace6b3b9
--- /dev/null
+++ b/man/man2type/mount_attr.2type
@@ -0,0 +1,58 @@
+
+.\" Copyright, the authors of the Linux man-pages project
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mount_attr 2type (date) "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 fields 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 fields specifies a file descriptor that indicates which user namespace to
+use as a reference for ID-mapped mounts with
+.BR MOUNT_ATTR_IDMAP .
+.SH VERSIONS
+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 STANDARDS
+Linux.
+.SH SEE ALSO
+.BR mount_setattr (2)

-- 
2.50.1