[PATCH 1/1][SRU][D] UBUNTU: SAUCE: Revert "UBUNTU: SAUCE: shiftfs: enable overlayfs on shiftfs"

[Seth Forshee]

BugLink: https://bugs.launchpad.net/bugs/1842382

This commit is causing the paths in /proc/self/maps to all show
up as / when proc is mounted over overlayfs in a chroot. Revert
the commit to fix the regression until a proper fix is found.

Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
---
 fs/open.c            | 4 +---
 fs/overlayfs/file.c  | 1 -
 fs/overlayfs/super.c | 5 ++---
 fs/shiftfs.c         | 4 +---
 include/linux/fs.h   | 3 +--
 5 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index c263d9f1372c..2fefa22cec99 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -933,15 +933,13 @@ struct file *dentry_open(const struct path *path, int flags,
 EXPORT_SYMBOL(dentry_open);
 
 struct file *open_with_fake_path(const struct path *path, int flags,
-				 struct inode *inode, struct dentry *dentry,
-				 const struct cred *cred)
+				struct inode *inode, const struct cred *cred)
 {
 	struct file *f = alloc_empty_file_noaccount(flags, cred);
 	if (!IS_ERR(f)) {
 		int error;
 
 		f->f_path = *path;
-		f->f_path.dentry = dentry;
 		error = do_dentry_open(f, inode, NULL);
 		if (error) {
 			fput(f);
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index fcc345207dc6..75d8d00fa087 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -34,7 +34,6 @@ static struct file *ovl_open_realfile(const struct file *file,
 
 	old_cred = ovl_override_creds(inode->i_sb);
 	realfile = open_with_fake_path(&file->f_path, flags, realinode,
-				       ovl_dentry_real(file->f_path.dentry),
 				       current_cred());
 	revert_creds(old_cred);
 
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b4fb0c402216..3bd48da819c2 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -753,14 +753,13 @@ static int ovl_mount_dir(const char *name, struct path *path)
 		ovl_unescape(tmp);
 		err = ovl_mount_dir_noesc(tmp, path);
 
-		if (!err) {
-			if ((path->dentry->d_sb->s_magic != SHIFTFS_MAGIC) && ovl_dentry_remote(path->dentry)) {
+		if (!err)
+			if (ovl_dentry_remote(path->dentry)) {
 				pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
 				       tmp);
 				path_put_init(path);
 				err = -EINVAL;
 			}
-		}
 		kfree(tmp);
 	}
 	return err;
diff --git a/fs/shiftfs.c b/fs/shiftfs.c
index 450e93b8b5b8..9006201c243d 100644
--- a/fs/shiftfs.c
+++ b/fs/shiftfs.c
@@ -1048,9 +1048,7 @@ static struct file *shiftfs_open_realfile(const struct file *file,
 	oldcred = shiftfs_override_creds(inode->i_sb);
 	/* XXX: open_with_fake_path() not gauranteed to stay around, if
 	 * removed use dentry_open() */
-	lowerf = open_with_fake_path(realpath, file->f_flags, loweri,
-				     realpath->dentry,
-				     info->creator_cred);
+	lowerf = open_with_fake_path(realpath, file->f_flags, loweri, info->creator_cred);
 	revert_creds(oldcred);
 
 	return lowerf;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 29ab8aa9551a..c4f9a8cde113 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2527,8 +2527,7 @@ extern struct file *file_open_root(struct dentry *, struct vfsmount *,
 				   const char *, int, umode_t);
 extern struct file * dentry_open(const struct path *, int, const struct cred *);
 extern struct file * open_with_fake_path(const struct path *, int,
-					 struct inode*, struct dentry *dentry,
-					 const struct cred *);
+					 struct inode*, const struct cred *);
 static inline struct file *file_clone_open(struct file *file)
 {
 	return dentry_open(&file->f_path, file->f_flags, file->f_cred);
-- 
2.20.1