linux-kernel - [RFC][PATCH v3 41/55] follow_dotdot(): expand the call of path_parent

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Message-Id: <20200301215240.873899-41-viro@ZenIV.linux.org.uk>
Date:   Sun,  1 Mar 2020 21:52:26 +0000
From:   Al Viro <viro@...IV.linux.org.uk>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [RFC][PATCH v3 41/55] follow_dotdot(): expand the call of path_parent_directory()

From: Al Viro <viro@...iv.linux.org.uk>

... and move the definition of path_parent_directory() towards
the last remaining user.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/namei.c | 42 ++++++++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 8e588632e03a..9b66cd00edcb 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1440,21 +1440,8 @@ static void follow_mount(struct path *path)
 	}
 }
 
-static struct dentry *path_parent_directory(struct path *path)
-{
-	/* rare case of legitimate dget_parent()... */
-	struct dentry *parent = dget_parent(path->dentry);
-
-	if (unlikely(!path_connected(path->mnt, parent))) {
-		dput(parent);
-		parent = NULL;
-	}
-	return parent;
-}
-
 static int follow_dotdot(struct nameidata *nd)
 {
-	struct dentry *parent;
 	while (1) {
 		if (path_equal(&nd->path, &nd->root)) {
 			if (unlikely(nd->flags & LOOKUP_BENEATH))
@@ -1462,9 +1449,13 @@ static int follow_dotdot(struct nameidata *nd)
 			break;
 		}
 		if (nd->path.dentry != nd->path.mnt->mnt_root) {
-			parent = path_parent_directory(&nd->path);
-			if (!parent)
+			/* rare case of legitimate dget_parent()... */
+			struct dentry *parent = dget_parent(nd->path.dentry);
+
+			if (unlikely(!path_connected(nd->path.mnt, parent))) {
+				dput(parent);
 				return -ENOENT;
+			}
 			dput(nd->path.dentry);
 			nd->path.dentry = parent;
 			break;
@@ -2600,6 +2591,17 @@ struct dentry *lookup_positive_unlocked(const char *name,
 EXPORT_SYMBOL(lookup_positive_unlocked);
 
 #ifdef CONFIG_UNIX98_PTYS
+static int path_parent_directory(struct path *path)
+{
+	struct dentry *old = path->dentry;
+	/* rare case of legitimate dget_parent()... */
+	path->dentry = dget_parent(path->dentry);
+	dput(old);
+	if (unlikely(!path_connected(path->mnt, path->dentry)))
+		return -ENOENT;
+	return 0;
+}
+
 int path_pts(struct path *path)
 {
 	/* Find something mounted on "pts" in the same directory as
@@ -2607,13 +2609,13 @@ int path_pts(struct path *path)
 	 */
 	struct dentry *child, *parent;
 	struct qstr this;
+	int ret;
 
-	parent = path_parent_directory(path);
-	if (!parent)
-		return -ENOENT;
+	ret = path_parent_directory(path);
+	if (ret)
+		return ret;
 
-	dput(path->dentry);
-	path->dentry = parent;
+	parent = path->dentry;
 	this.name = "pts";
 	this.len = 3;
 	child = d_hash_and_lookup(parent, &this);
-- 
2.11.0