@@ -58,6 +58,8 @@ static int calculate_f_flags(struct vfsmount *mnt)
if (IS_MNT_SLAVE(real_mount(mnt)))
flags |= ST_SLAVE;
+ else if (!(flags & ST_SHARED))
+ flags |= ST_PRIVATE;
return flags;
}
@@ -41,6 +41,7 @@ struct kstatfs {
#define ST_NODIRATIME (1<<11) /* do not update directory access times */
#define ST_RELATIME (1<<12) /* update atime relative to mtime/ctime */
#define ST_UNBINDABLE (1<<17) /* change to unbindable */
+#define ST_PRIVATE (1<<18) /* change to private */
#define ST_SLAVE (1<<19) /* change to slave */
#define ST_SHARED (1<<20) /* change to shared */
Currently userspace can only determine whether a mountpoint is private by parsing /proc/<pid>/mountinfo. It would be convenient to simply retrieve this property with a statvfs() call. This let's userspace avoid costly parsing, supports cases where /proc is not mounted, and supports usecases where file descriptors to mountpoints are passed between processes that are inspected via fstatvfs(). A mountpoint is considered ST_PRIVATE iff and it is neither ST_SLAVE nor ST_SHARED. Signed-off-by: Christian Brauner <christian@brauner.io> --- v0->v1: * non-functional changes: extend commit message --- fs/statfs.c | 2 ++ include/linux/statfs.h | 1 + 2 files changed, 3 insertions(+)