switch create_mnt_ns() to saner calling conventions, fix double mntput() in nfs

Life is much saner if create_mnt_ns(mnt) drops mnt in case of error...
Switch it to such calling conventions, switch callers, fix double mntput() in
fs/nfs/super.c one.

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

3 files changed, 11 insertions, 18 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 969a7747e889..cfbedd7755b0 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -843,10 +843,8 @@ static struct dentry *mount_subvol(const char *subvol_name, int flags,
                 return ERR_CAST(mnt);
 
         ns_private = create_mnt_ns(mnt);
-        if (IS_ERR(ns_private)) {
-                mntput(mnt);
+        if (IS_ERR(ns_private))
                 return ERR_CAST(ns_private);
-        }
 
         /*
          * This will trigger the automount of the subvol so we can just
diff --git a/fs/namespace.c b/fs/namespace.c
index e5e1c7d1839b..aea4b7689840 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2483,6 +2483,8 @@ struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt)
                 __mnt_make_longterm(mnt);
                 new_ns->root = mnt;
                 list_add(&new_ns->list, &new_ns->root->mnt_list);
+        } else {
+                mntput(mnt);
         }
         return new_ns;
 }
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 480b3b6bf71e..46d69f38fd55 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2794,22 +2794,21 @@ static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
         int ret;
 
         ns_private = create_mnt_ns(root_mnt);
-        ret = PTR_ERR(ns_private);
         if (IS_ERR(ns_private))
-                goto out_mntput;
+                return ERR_CAST(ns_private);
 
         ret = nfs_referral_loop_protect();
-        if (ret != 0)
-                goto out_put_mnt_ns;
-
-        ret = vfs_path_lookup(root_mnt->mnt_root, root_mnt,
-                        export_path, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
+        if (ret == 0) {
+                ret = vfs_path_lookup(root_mnt->mnt_root, root_mnt,
+                                export_path, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT,
+                                &path);
+                nfs_referral_loop_unprotect();
+        }
 
-        nfs_referral_loop_unprotect();
         put_mnt_ns(ns_private);
 
         if (ret != 0)
-                goto out_err;
+                return ERR_PTR(ret);
 
         s = path.mnt->mnt_sb;
         atomic_inc(&s->s_active);
@@ -2818,12 +2817,6 @@ static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
         path_put(&path);
         down_write(&s->s_umount);
         return dentry;
-out_put_mnt_ns:
-        put_mnt_ns(ns_private);
-out_mntput:
-        mntput(root_mnt);
-out_err:
-        return ERR_PTR(ret);
 }
 
 static struct dentry *nfs4_try_mount(int flags, const char *dev_name,