From 7925dad839e70ab43140e26d6b93e807b5969f05 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Tue, 17 Mar 2020 15:04:22 +0100
Subject: [PATCH] ovl: separate detection of remote upper layer from stacked
 overlay

Following patch will allow remote as upper layer, but not overlay stacked
on upper layer.  Separate the two concepts.

This patch is doesn't change behavior.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/overlayfs/namei.c |  3 ++-
 fs/overlayfs/super.c | 14 +++++++-------
 fs/overlayfs/util.c  |  3 +--
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index ed9e129fae04..a5b998a93a24 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -845,7 +845,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		if (err)
 			goto out;
 
-		if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {
+		if (upperdentry && (upperdentry->d_flags & DCACHE_OP_REAL ||
+				    unlikely(ovl_dentry_remote(upperdentry)))) {
 			dput(upperdentry);
 			err = -EREMOTE;
 			goto out;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index a05bf1179ce0..bc35cd6233ee 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -752,13 +752,13 @@ static int ovl_mount_dir(const char *name, struct path *path)
 		ovl_unescape(tmp);
 		err = ovl_mount_dir_noesc(tmp, path);
 
-		if (!err)
-			if (ovl_dentry_remote(path->dentry)) {
-				pr_err("filesystem on '%s' not supported as upperdir\n",
-				       tmp);
-				path_put_init(path);
-				err = -EINVAL;
-			}
+		if (!err && (ovl_dentry_remote(path->dentry) ||
+			     path->dentry->d_flags & DCACHE_OP_REAL)) {
+			pr_err("filesystem on '%s' not supported as upperdir\n",
+			       tmp);
+			path_put_init(path);
+			err = -EINVAL;
+		}
 		kfree(tmp);
 	}
 	return err;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index f318e4811e32..997c31509c91 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -93,8 +93,7 @@ struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 bool ovl_dentry_remote(struct dentry *dentry)
 {
 	return dentry->d_flags &
-		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
-		 DCACHE_OP_REAL);
+		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
 }
 
 bool ovl_dentry_weird(struct dentry *dentry)