mount_namespaces.7: SEE ALSO: add mount_setattr(2)

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/fanotify_mark.2

@@ -83,7 +83,7 @@ contains
 .BR FAN_MARK_FILESYSTEM ,
 all marks for filesystems are removed from the group.
 Otherwise, all marks for directories and files are removed.
-No flag other than and at most one of the flags
+No flag other than, and at most one of, the flags
 .B FAN_MARK_MOUNT
 or
 .B FAN_MARK_FILESYSTEM

man2/mount.2

@@ -960,6 +960,7 @@ for details of this file.
 .BR mountpoint (1),
 .BR chroot (2),
 .BR ioctl_iflags (2),
+.BR mount_settatr (2),
 .BR pivot_root (2),
 .BR umount (2),
 .BR mount_namespaces (7),

man2/mount_setattr.2

@@ -897,7 +897,8 @@ static inline int
 mount_setattr(int dirfd, const char *pathname, unsigned int flags,
               struct mount_attr *attr, size_t size)
 {
-    return syscall(SYS_mount_setattr, dirfd, pathname, flags, attr, size);
+    return syscall(SYS_mount_setattr, dirfd, pathname, flags,
+                   attr, size);
 }
 
 static inline int
@@ -980,6 +981,18 @@ main(int argc, char *argv[])
 
     /* In the following, \-1 as the \(aqdirfd\(aq argument ensures that
        open_tree() fails if \(aqsource\(aq is not an absolute pathname. */
+.\" Christian Brauner
+.\"     When writing programs I like to never use relative paths with AT_FDCWD
+.\"     because. Because making assumptions about the current working directory
+.\"     of the calling process is just too easy to get wrong; especially when
+.\"     pivot_root() or chroot() are in play.
+.\"     My absolut preference (joke intended) is to open a well-known starting
+.\"     point with an absolute path to get a dirfd and then scope all future
+.\"     operations beneath that dirfd. This already works with old-style
+.\"     openat() and _very_ cautious programming but openat2() and its
+.\"     resolve-flag space have made this **chef's kiss**.
+.\"     If I can't operate based on a well-known dirfd I use absolute paths
+.\"     with a -EBADF dirfd passed to *at() functions.
 
     int fd_tree = open_tree(\-1, source,
                        OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC |

man2/open.2

@@ -1642,6 +1642,7 @@ a directory file descriptor argument
 .BR linkat (2),
 .BR mkdirat (2),
 .BR mknodat (2),
+.BR mount_setattr (2),
 .BR move_mount (2),
 .BR name_to_handle_at (2),
 .BR open_tree (2),

man2/statx.2

@@ -77,6 +77,7 @@ struct statx {
        containing the filesystem where the file resides */
     __u32 stx_dev_major;   /* Major ID */
     __u32 stx_dev_minor;   /* Minor ID */
+    __u64 stx_mnt_id;      /* Mount ID */
 };
 .EE
 .in
@@ -258,6 +259,7 @@ STATX_SIZE	Want stx_size
 STATX_BLOCKS	Want stx_blocks
 STATX_BASIC_STATS	[All of the above]
 STATX_BTIME	Want stx_btime
+STATX_MNT_ID	Want stx_mnt_id (since Linux 5.8)
 STATX_ALL	[All currently available fields]
 .TE
 .in
@@ -411,6 +413,14 @@ The device on which this file (inode) resides.
 .IR stx_rdev_major " and "  stx_rdev_minor
 The device that this file (inode) represents if the file is of block or
 character device type.
+.TP
+.I stx_mnt_id
+.\" commit fa2fcf4f1df1559a0a4ee0f46915b496cc2ebf60
+The mount ID of the mount containing the file.
+This is the same number reported by
+.BR name_to_handle_at (2)
+and corresponds to the number in the first field in one of the records in
+.IR /proc/self/mountinfo .
 .PP
 For further information on the above fields, see
 .BR inode (7).
@@ -573,9 +583,11 @@ is Linux-specific.
 .BR access (2),
 .BR chmod (2),
 .BR chown (2),
+.BR name_to_handle_at (2),
 .BR readlink (2),
 .BR stat (2),
 .BR utime (2),
+.BR proc (5),
 .BR capabilities (7),
 .BR inode (7),
 .BR symlink (7)

man7/mount_namespaces.7

@@ -1124,6 +1124,7 @@ See
 .BR unshare (1),
 .BR clone (2),
 .BR mount (2),
+.BR mount_setattr (2),
 .BR pivot_root (2),
 .BR setns (2),
 .BR umount (2),