vfs: syscall: Add move_mount(2) to move mounts around

Add a move_mount() system call that will move a mount from one place to
another and, in the next commit, allow to attach an unattached mount tree.

The new system call looks like the following:

	int move_mount(int from_dfd, const char *from_path,
		       int to_dfd, const char *to_path,
		       unsigned int flags);

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/security.h b/include/linux/security.h
index 49f2685324b0..1f2e06afc28f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -250,6 +250,7 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb,
 				unsigned long *set_kern_flags);
 int security_add_mnt_opt(const char *option, const char *val,
 				int len, void **mnt_opts);
+int security_move_mount(const struct path *from_path, const struct path *to_path);
 int security_dentry_init_security(struct dentry *dentry, int mode,
 					const struct qstr *name, void **ctx,
 					u32 *ctxlen);
@@ -611,6 +612,12 @@ static inline int security_add_mnt_opt(const char *option, const char *val,
 	return 0;
 }
 
+static inline int security_move_mount(const struct path *from_path,
+				      const struct path *to_path)
+{
+	return 0;
+}
+
 static inline int security_inode_alloc(struct inode *inode)
 {
 	return 0;