2.5 and mount MS_MOVE

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chrisat_private

would it be useful to add a new hook for this new mount option?  the
superblock hasn't changed, but the mount point has.
see fs/namespace.c::do_move_mount().  a hook in attach_mnt() would get
this case as well as the pivot_root() case.  however this would effect
graft_tree(), which we don't hook in to avoid the MS_BIND case (iirc).

moving the check_sb() and post_add_mount() hooks into graft_tree() ought
to do it.  and check_sb() would have to notice if sb->s_security had
already been initialized.

comments/flames?

thanks,
-chris

===== namespace.c 1.11 vs edited =====

--- 1.11/fs/namespace.c	Mon Dec 17 00:07:10 2001
+++ edited/namespace.c	Tue Dec 18 21:45:57 2001
@@ -480,6 +480,10 @@
 	if (IS_DEADDIR(nd->dentry->d_inode))
 		goto out_unlock;
 
+	err = security_ops->sb_ops->check_sb(mnt, nd);
+	if (err)
+		goto out_unlock;
+
 	spin_lock(&dcache_lock);
 	if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) {
 		struct list_head head;
@@ -492,6 +496,8 @@
 	spin_unlock(&dcache_lock);
 out_unlock:
 	up(&nd->dentry->d_inode->i_zombie);
+	if (!err)
+		security_ops->sb_ops->post_addmount(mnt, nd);
 	return err;
 }
 
@@ -651,12 +657,7 @@
 		goto unlock;
 
 	mnt->mnt_flags = mnt_flags;
-	err = security_ops->sb_ops->check_sb(mnt, nd);
-	if (err)
-		goto unlock;
 	err = graft_tree(mnt, nd);
-	if (!err)
-		security_ops->sb_ops->post_addmount(mnt, nd);
 unlock:
 	up(&mount_sem);
 	mntput(mnt);
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