hypfs: Fix error number left in struct pointer member

BugLink: https://bugs.launchpad.net/bugs/1848598

[ Upstream commit b54c64f7 ]

In hypfs_fill_super(), if hypfs_create_update_file() fails,
sbi->update_file is left holding an error number.  This is passed to
hypfs_kill_super() which doesn't check for this.

Fix this by not setting sbi->update_value until after we've checked for
error.

Fixes: 24bbb1fa ("[PATCH] s390_hypfs filesystem")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
cc: Heiko Carstens <heiko.carstens@de.ibm.com>
cc: linux-s390@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/s390/hypfs/inode.c

@@ -267,7 +267,7 @@ static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct inode *root_inode;
-	struct dentry *root_dentry;
+	struct dentry *root_dentry, *update_file;
 	int rc = 0;
 	struct hypfs_sb_info *sbi;
 
@@ -298,9 +298,10 @@ static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 		rc = hypfs_diag_create_files(root_dentry);
 	if (rc)
 		return rc;
-	sbi->update_file = hypfs_create_update_file(root_dentry);
-	if (IS_ERR(sbi->update_file))
-		return PTR_ERR(sbi->update_file);
+	update_file = hypfs_create_update_file(root_dentry);
+	if (IS_ERR(update_file))
+		return PTR_ERR(update_file);
+	sbi->update_file = update_file;
 	hypfs_update_update(sb);
 	pr_info("Hypervisor filesystem mounted\n");
 	return 0;