linux-kernel - [PATCH 34/38] union-mount: Implement union-aware chmod()/fchmodat()

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Date:	Fri, 25 Jun 2010 12:05:24 -0700
From:	Valerie Aurora <vaurora@...hat.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	Miklos Szeredi <miklos@...redi.hu>, Jan Blunck <jblunck@...e.de>,
	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Valerie Aurora <vaurora@...hat.com>
Subject: [PATCH 34/38] union-mount: Implement union-aware chmod()/fchmodat()

---
 fs/open.c |   25 +++++++++++++++++++++----
 1 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index 3c1ae55..336fe01 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -669,18 +669,32 @@ out:
 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
 {
 	struct path path;
+	struct nameidata nd;
+	struct vfsmount *mnt;
 	struct inode *inode;
+	char *tmp;
 	int error;
 	struct iattr newattrs;
 
-	error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
+	error = user_path_nd(dfd, filename, LOOKUP_FOLLOW, &nd,
+				     &path, &tmp);
 	if (error)
 		goto out;
-	inode = path.dentry->d_inode;
 
-	error = mnt_want_write(path.mnt);
+	if (IS_DIR_UNIONED(nd.path.dentry))
+		mnt = nd.path.mnt;
+	else
+		mnt = path.mnt;
+
+	error = mnt_want_write(mnt);
 	if (error)
 		goto dput_and_out;
+
+	error = union_copyup(&nd, &path);
+	if (error)
+		goto mnt_drop_write_and_out;
+
+	inode = path.dentry->d_inode;
 	mutex_lock(&inode->i_mutex);
 	error = security_path_chmod(path.dentry, path.mnt, mode);
 	if (error)
@@ -692,9 +706,12 @@ SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
 	error = notify_change(path.dentry, &newattrs);
 out_unlock:
 	mutex_unlock(&inode->i_mutex);
-	mnt_drop_write(path.mnt);
+mnt_drop_write_and_out:
+	mnt_drop_write(mnt);
 dput_and_out:
 	path_put(&path);
+	path_put(&nd.path);
+	putname(tmp);
 out:
 	return error;
 }
-- 
1.6.3.3

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