linux-kernel - [PATCH 4.14 22/54] devpts: hoist out check for DEVPTS_SUPER

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Date:   Mon, 16 Jul 2018 09:35:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Christian Brauner <christian.brauner@...ntu.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.14 22/54] devpts: hoist out check for DEVPTS_SUPER_MAGIC

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christian Brauner <christian.brauner@...ntu.com>

commit 7d71109df186d630a41280670c8d71d0cf9b0da9 upstream.

Hoist the check whether we have already found a suitable devpts filesystem
out of devpts_ptmx_path() in preparation for the devpts bind-mount
resolution patch. This is a non-functional change.

Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@...ssion.com>
Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/devpts/inode.c |   26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -138,10 +138,6 @@ static int devpts_ptmx_path(struct path
 	struct super_block *sb;
 	int err;
 
-	/* Has the devpts filesystem already been found? */
-	if (path->mnt->mnt_sb->s_magic == DEVPTS_SUPER_MAGIC)
-		return 0;
-
 	/* Is a devpts filesystem at "pts" in the same directory? */
 	err = path_pts(path);
 	if (err)
@@ -159,21 +155,25 @@ static int devpts_ptmx_path(struct path
 struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi)
 {
 	struct path path;
-	int err;
+	int err = 0;
 
 	path = filp->f_path;
 	path_get(&path);
 
-	err = devpts_ptmx_path(&path);
+	/* Has the devpts filesystem already been found? */
+	if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC)
+		err = devpts_ptmx_path(&path);
 	dput(path.dentry);
 	if (err) {
 		mntput(path.mnt);
 		return ERR_PTR(err);
 	}
+
 	if (DEVPTS_SB(path.mnt->mnt_sb) != fsi) {
 		mntput(path.mnt);
 		return ERR_PTR(-ENODEV);
 	}
+
 	return path.mnt;
 }
 
@@ -182,15 +182,19 @@ struct pts_fs_info *devpts_acquire(struc
 	struct pts_fs_info *result;
 	struct path path;
 	struct super_block *sb;
-	int err;
 
 	path = filp->f_path;
 	path_get(&path);
 
-	err = devpts_ptmx_path(&path);
-	if (err) {
-		result = ERR_PTR(err);
-		goto out;
+	/* Has the devpts filesystem already been found? */
+	if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) {
+		int err;
+
+		err = devpts_ptmx_path(&path);
+		if (err) {
+			result = ERR_PTR(err);
+			goto out;
+		}
 	}
 
 	/*