linux-kernel - [PATCH 08/73] VFS: Add CL_NO_SHARED flag to clone_mnt()/copy

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Message-ID: <20120221175825.25235.96185.stgit@warthog.procyon.org.uk>
Date:	Tue, 21 Feb 2012 17:58:25 +0000
From:	David Howells <dhowells@...hat.com>
To:	linux-fsdevel@...r.kernel.org, viro@...IV.linux.org.uk,
	valerie.aurora@...il.com
Cc:	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>,
	Ram Pai <linuxram@...ibm.com>
Subject: [PATCH 08/73] VFS: Add CL_NO_SHARED flag to clone_mnt()/copy_tree()
 [ver #2]

From: Valerie Aurora <vaurora@...hat.com>

Passing the CL_NO_SHARED flag to clone_mnt() causes the clone to fail
if the source mnt is shared.

Original-author: Valerie Aurora <vaurora@...hat.com>
Signed-off-by: David Howells <dhowells@...hat.com>
Cc: Ram Pai <linuxram@...ibm.com>
---

 fs/namespace.c |    3 +++
 fs/pnode.h     |    1 +
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 35c3b80..f92f574 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -740,6 +740,9 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
 	struct mount *mnt;
 	int err;
 
+	if ((flag & CL_NO_SHARED) && IS_MNT_SHARED(old))
+		return ERR_PTR(-EINVAL);
+
 	mnt = alloc_vfsmnt(old->mnt_devname);
 	if (!mnt)
 		return ERR_PTR(-ENOMEM);
diff --git a/fs/pnode.h b/fs/pnode.h
index 65c6097..c7089dd 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -22,6 +22,7 @@
 #define CL_COPY_ALL 		0x04
 #define CL_MAKE_SHARED 		0x08
 #define CL_PRIVATE 		0x10
+#define CL_NO_SHARED 		0x20
 
 static inline void set_mnt_shared(struct mount *mnt)
 {

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