linux-kernel - [PATCH 04/13] devpts: Stop rolling devpts_remount by hand in devpts

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Date:	Mon,  4 Apr 2016 20:29:20 -0500
From:	"Eric W. Biederman" <ebiederm@...ssion.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Peter Hurley <peter@...leysoftware.com>,
	Greg KH <greg@...ah.com>, Jiri Slaby <jslaby@...e.com>,
	Aurelien Jarno <aurelien@...el32.net>,
	Andy Lutomirski <luto@...capital.net>,
	Florian Weimer <fw@...eb.enyo.de>,
	Al Viro <viro@...iv.linux.org.uk>,
	Serge Hallyn <serge.hallyn@...ntu.com>,
	Jann Horn <jann@...jh.net>,
	"security@...nel.org" <security@...nel.org>, security@...ntu.com,
	security@...ian.org, Willy Tarreau <w@....eu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 04/13] devpts: Stop rolling devpts_remount by hand in devpts_mount

Just use devpts_remount and by doing so ensuring that ptxmode
actually get propogated to /dev/pts/ptmx on the initial mount
of devpts.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 fs/devpts/inode.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index c3d53d2f7c3e..14be886f987c 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -338,12 +338,6 @@ static int mknod_ptmx(struct super_block *sb)
 
 	inode_lock(d_inode(root));
 
-	/* If we have already created ptmx node, return */
-	if (fsi->ptmx_dentry) {
-		rc = 0;
-		goto out;
-	}
-
 	dentry = d_alloc_name(root, "ptmx");
 	if (!dentry) {
 		pr_err("Unable to alloc dentry for ptmx node\n");
@@ -552,16 +546,20 @@ static struct dentry *devpts_mount(struct file_system_type *fs_type,
 		error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
 		if (error)
 			goto out_undo_sget;
-		s->s_flags |= MS_ACTIVE;
-	}
 
-	error = parse_mount_options(data, &DEVPTS_SB(s)->mount_opts);
-	if (error)
-		goto out_undo_sget;
+		error = parse_mount_options(data, &DEVPTS_SB(s)->mount_opts);
+		if (error)
+			goto out_undo_sget;
+
+		error = mknod_ptmx(s);
+		if (error)
+			goto out_undo_sget;
 
-	error = mknod_ptmx(s);
-	if (error)
-		goto out_undo_sget;
+		s->s_flags |= MS_ACTIVE;
+	} else {
+		/* Match mount_single ignore errors on remount */
+		devpts_remount(s, &flags, data);
+	}
 
 	return dget(s->s_root);
 
-- 
2.6.3