ovl: handle idmappings in creation operations

When creating objects in the upper layer we need to pass down the upper
idmapping into the respective vfs helpers in order to support idmapped
base layers. The vfs helpers will take care of the rest.

Cc: <linux-unionfs@vger.kernel.org>
Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/overlayfs.h

@@ -125,7 +125,7 @@ static inline const char *ovl_xattr(struct ovl_fs *ofs, enum ovl_xattr ox)
 static inline int ovl_do_rmdir(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry)
 {
-	int err = vfs_rmdir(&init_user_ns, dir, dentry);
+	int err = vfs_rmdir(ovl_upper_mnt_userns(ofs), dir, dentry);
 
 	pr_debug("rmdir(%pd2) = %i\n", dentry, err);
 	return err;
@@ -134,7 +134,7 @@ static inline int ovl_do_rmdir(struct ovl_fs *ofs,
 static inline int ovl_do_unlink(struct ovl_fs *ofs, struct inode *dir,
 				struct dentry *dentry)
 {
-	int err = vfs_unlink(&init_user_ns, dir, dentry, NULL);
+	int err = vfs_unlink(ovl_upper_mnt_userns(ofs), dir, dentry, NULL);
 
 	pr_debug("unlink(%pd2) = %i\n", dentry, err);
 	return err;
@@ -143,7 +143,7 @@ static inline int ovl_do_unlink(struct ovl_fs *ofs, struct inode *dir,
 static inline int ovl_do_link(struct ovl_fs *ofs, struct dentry *old_dentry,
 			      struct inode *dir, struct dentry *new_dentry)
 {
-	int err = vfs_link(old_dentry, &init_user_ns, dir, new_dentry, NULL);
+	int err = vfs_link(old_dentry, ovl_upper_mnt_userns(ofs), dir, new_dentry, NULL);
 
 	pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
 	return err;
@@ -153,7 +153,7 @@ static inline int ovl_do_create(struct ovl_fs *ofs,
 				struct inode *dir, struct dentry *dentry,
 				umode_t mode)
 {
-	int err = vfs_create(&init_user_ns, dir, dentry, mode, true);
+	int err = vfs_create(ovl_upper_mnt_userns(ofs), dir, dentry, mode, true);
 
 	pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
 	return err;
@@ -163,7 +163,7 @@ static inline int ovl_do_mkdir(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry,
 			       umode_t mode)
 {
-	int err = vfs_mkdir(&init_user_ns, dir, dentry, mode);
+	int err = vfs_mkdir(ovl_upper_mnt_userns(ofs), dir, dentry, mode);
 	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
 	return err;
 }
@@ -172,7 +172,7 @@ static inline int ovl_do_mknod(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry,
 			       umode_t mode, dev_t dev)
 {
-	int err = vfs_mknod(&init_user_ns, dir, dentry, mode, dev);
+	int err = vfs_mknod(ovl_upper_mnt_userns(ofs), dir, dentry, mode, dev);
 
 	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
 	return err;
@@ -182,7 +182,7 @@ static inline int ovl_do_symlink(struct ovl_fs *ofs,
 				 struct inode *dir, struct dentry *dentry,
 				 const char *oldname)
 {
-	int err = vfs_symlink(&init_user_ns, dir, dentry, oldname);
+	int err = vfs_symlink(ovl_upper_mnt_userns(ofs), dir, dentry, oldname);
 
 	pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
 	return err;
@@ -245,10 +245,10 @@ static inline int ovl_do_rename(struct ovl_fs *ofs, struct inode *olddir,
 {
 	int err;
 	struct renamedata rd = {
-		.old_mnt_userns	= &init_user_ns,
+		.old_mnt_userns	= ovl_upper_mnt_userns(ofs),
 		.old_dir 	= olddir,
 		.old_dentry 	= olddentry,
-		.new_mnt_userns	= &init_user_ns,
+		.new_mnt_userns	= ovl_upper_mnt_userns(ofs),
 		.new_dir 	= newdir,
 		.new_dentry 	= newdentry,
 		.flags 		= flags,
@@ -266,7 +266,7 @@ static inline int ovl_do_rename(struct ovl_fs *ofs, struct inode *olddir,
 static inline int ovl_do_whiteout(struct ovl_fs *ofs,
 				  struct inode *dir, struct dentry *dentry)
 {
-	int err = vfs_whiteout(&init_user_ns, dir, dentry);
+	int err = vfs_whiteout(ovl_upper_mnt_userns(ofs), dir, dentry);
 	pr_debug("whiteout(%pd2) = %i\n", dentry, err);
 	return err;
 }
@@ -274,7 +274,7 @@ static inline int ovl_do_whiteout(struct ovl_fs *ofs,
 static inline struct dentry *ovl_do_tmpfile(struct ovl_fs *ofs,
 					    struct dentry *dentry, umode_t mode)
 {
-	struct dentry *ret = vfs_tmpfile(&init_user_ns, dentry, mode, 0);
+	struct dentry *ret = vfs_tmpfile(ovl_upper_mnt_userns(ofs), dentry, mode, 0);
 	int err = PTR_ERR_OR_ZERO(ret);
 
 	pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);