From fe2d3c2473d3db146ae2a2823549abdfa380ca51 Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk@google.com>
Date: Wed, 4 Jan 2023 13:00:04 -0800
Subject: [PATCH] Revert "fs: add is_idmapped_mnt() helper"

This reverts commit bac0953c9fe0665c8813cb620b24f035ed4f0da2.
---
 fs/cachefiles/bind.c |  2 +-
 fs/ecryptfs/main.c   |  2 +-
 fs/namespace.c       |  2 +-
 fs/nfsd/export.c     |  2 +-
 fs/overlayfs/super.c |  2 +-
 fs/proc_namespace.c  |  2 +-
 include/linux/fs.h   | 14 --------------
 7 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c
index 146291be6263..d463d89f5db8 100644
--- a/fs/cachefiles/bind.c
+++ b/fs/cachefiles/bind.c
@@ -117,7 +117,7 @@ static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
 	root = path.dentry;
 
 	ret = -EINVAL;
-	if (is_idmapped_mnt(path.mnt)) {
+	if (mnt_user_ns(path.mnt) != &init_user_ns) {
 		pr_warn("File cache on idmapped mounts not supported");
 		goto error_unsupported;
 	}
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 2dd23a82e0de..d66bbd2df191 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -537,7 +537,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
 		goto out_free;
 	}
 
-	if (is_idmapped_mnt(path.mnt)) {
+	if (mnt_user_ns(path.mnt) != &init_user_ns) {
 		rc = -EINVAL;
 		printk(KERN_ERR "Mounting on idmapped mounts currently disallowed\n");
 		goto out_free;
diff --git a/fs/namespace.c b/fs/namespace.c
index 4994b816a74c..659a8f39c61a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3936,7 +3936,7 @@ static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt)
 	 * mapping. It makes things simpler and callers can just create
 	 * another bind-mount they can idmap if they want to.
 	 */
-	if (is_idmapped_mnt(m))
+	if (mnt_user_ns(m) != &init_user_ns)
 		return -EPERM;
 
 	/* The underlying filesystem doesn't support idmapped mounts yet. */
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 668c7527b17e..9421dae22737 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -427,7 +427,7 @@ static int check_export(struct path *path, int *flags, unsigned char *uuid)
 		return -EINVAL;
 	}
 
-	if (is_idmapped_mnt(path->mnt)) {
+	if (mnt_user_ns(path->mnt) != &init_user_ns) {
 		dprintk("exp_export: export of idmapped mounts not yet supported.\n");
 		return -EINVAL;
 	}
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 31ebe4061460..178daa5e82c9 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -869,7 +869,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path)
 		pr_err("filesystem on '%s' not supported\n", name);
 		goto out_put;
 	}
-	if (is_idmapped_mnt(path->mnt)) {
+	if (mnt_user_ns(path->mnt) != &init_user_ns) {
 		pr_err("idmapped layers are currently not supported\n");
 		goto out_put;
 	}
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 49650e54d2f8..392ef5162655 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -80,7 +80,7 @@ static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
 			seq_puts(m, fs_infop->str);
 	}
 
-	if (is_idmapped_mnt(mnt))
+	if (mnt_user_ns(mnt) != &init_user_ns)
 		seq_puts(m, ",idmapped");
 }
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 090c478ba12f..af7a9a1fbc25 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2724,20 +2724,6 @@ static inline struct user_namespace *file_mnt_user_ns(struct file *file)
 {
 	return mnt_user_ns(file->f_path.mnt);
 }
-
-/**
- * is_idmapped_mnt - check whether a mount is mapped
- * @mnt: the mount to check
- *
- * If @mnt has an idmapping attached to it @mnt is mapped.
- *
- * Return: true if mount is mapped, false if not.
- */
-static inline bool is_idmapped_mnt(const struct vfsmount *mnt)
-{
-	return mnt_user_ns(mnt) != &init_user_ns;
-}
-
 extern long vfs_truncate(const struct path *, loff_t);
 int do_truncate(struct user_namespace *, struct dentry *, loff_t start,
 		unsigned int time_attrs, struct file *filp);