selinux: Use simple_start_creating() / simple_done_creating()

Instead of explicitly locking the parent and performing a lookup in
selinux, use simple_start_creating(), and then use
simple_done_creating() to unlock.

This extends the region that the directory is locked for, and also
performs a lookup.
The lock extension is of no real consequence.
The lookup uses simple_lookup() and so always succeeds.  Thus when
d_make_persistent() is called the dentry will already be hashed.
d_make_persistent() handles this case.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20260224222542.3458677-7-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 3245cc531555b64e59404c839c12f971b4f221fa..83aa765a09f98db90936ca898e9ed92982572891 100644 (file)
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -1931,27 +1931,26 @@ static const struct inode_operations swapover_dir_inode_operations = {
 static struct dentry *sel_make_swapover_dir(struct super_block *sb,
                                                unsigned long *ino)
 {
-       struct dentry *dentry = d_alloc_name(sb->s_root, ".swapover");
+       struct dentry *dentry;
        struct inode *inode;
 
-       if (!dentry)
-               return ERR_PTR(-ENOMEM);
-
        inode = sel_make_inode(sb, S_IFDIR);
-       if (!inode) {
-               dput(dentry);
+       if (!inode)
                return ERR_PTR(-ENOMEM);
+
+       dentry = simple_start_creating(sb->s_root, ".swapover");
+       if (IS_ERR(dentry)) {
+               iput(inode);
+               return dentry;
        }
 
        inode->i_op = &swapover_dir_inode_operations;
        inode->i_ino = ++(*ino);
        /* directory inodes start off with i_nlink == 2 (for "." entry) */
        inc_nlink(inode);
-       inode_lock(sb->s_root->d_inode);
        d_make_persistent(dentry, inode);
        inc_nlink(sb->s_root->d_inode);
-       inode_unlock(sb->s_root->d_inode);
-       dput(dentry);
+       simple_done_creating(dentry);
        return dentry;  // borrowed
 }