securityfs: pin filesystem only for objects directly in root

Nothing on securityfs ever changes parents, so we don't need
to pin the internal mount if it's already pinned for parent.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/security/inode.c b/security/inode.c
index 93460eab8216bb75d38270a5d8f7fdeb42afcfc3..1ecb8859c27205fe5e84fb09c4b6f643fa3d8d7d 100644 (file)
--- a/security/inode.c
+++ b/security/inode.c
@@ -112,18 +112,20 @@ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
        struct dentry *dentry;
        struct inode *dir, *inode;
        int error;
+       bool pinned = false;
 
        if (!(mode & S_IFMT))
                mode = (mode & S_IALLUGO) | S_IFREG;
 
        pr_debug("securityfs: creating file '%s'\n",name);
 
-       error = simple_pin_fs(&fs_type, &mount, &mount_count);
-       if (error)
-               return ERR_PTR(error);
-
-       if (!parent)
+       if (!parent) {
+               error = simple_pin_fs(&fs_type, &mount, &mount_count);
+               if (error)
+                       return ERR_PTR(error);
+               pinned = true;
                parent = mount->mnt_root;
+       }
 
        dir = d_inode(parent);
 
@@ -167,7 +169,8 @@ out1:
        dentry = ERR_PTR(error);
 out:
        inode_unlock(dir);
-       simple_release_fs(&mount, &mount_count);
+       if (pinned)
+               simple_release_fs(&mount, &mount_count);
        return dentry;
 }
 
@@ -307,13 +310,15 @@ void securityfs_remove(struct dentry *dentry)
                        simple_unlink(dir, dentry);
        }
        inode_unlock(dir);
-       simple_release_fs(&mount, &mount_count);
+       if (dir == dir->i_sb->s_root->d_inode)
+               simple_release_fs(&mount, &mount_count);
 }
 EXPORT_SYMBOL_GPL(securityfs_remove);
 
 static void remove_one(struct dentry *victim)
 {
-       simple_release_fs(&mount, &mount_count);
+       if (victim->d_parent == victim->d_sb->s_root)
+               simple_release_fs(&mount, &mount_count);
 }
 
 /**