linux-kernel - [RFC][PATCH 12/30] r/o bind mounts: elevate mnt

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Message-Id: <20080208222703.5A70B0CF@kernel>
Date:	Fri, 08 Feb 2008 14:27:03 -0800
From:	Dave Hansen <haveblue@...ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	hch@....de, viro@...IV.linux.org.uk, viro@....linux.org.uk,
	miklos@...redi.hu, Dave Hansen <haveblue@...ibm.com>
Subject: [RFC][PATCH 12/30] r/o bind mounts: elevate mnt_writers for unlink callers



Signed-off-by: Dave Hansen <haveblue@...ibm.com>
---

 linux-2.6.git-dave/fs/namei.c   |    4 ++++
 linux-2.6.git-dave/ipc/mqueue.c |    5 ++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff -puN fs/namei.c~r-o-bind-mounts-elevate-mnt-writers-for-vfs_unlink-callers fs/namei.c
--- linux-2.6.git/fs/namei.c~r-o-bind-mounts-elevate-mnt-writers-for-vfs_unlink-callers	2008-02-08 13:04:50.000000000 -0800
+++ linux-2.6.git-dave/fs/namei.c	2008-02-08 13:04:50.000000000 -0800
@@ -2278,7 +2278,11 @@ static long do_unlinkat(int dfd, const c
 		inode = dentry->d_inode;
 		if (inode)
 			atomic_inc(&inode->i_count);
+		error = mnt_want_write(nd.mnt);
+		if (error)
+			goto exit2;
 		error = vfs_unlink(nd.dentry->d_inode, dentry);
+		mnt_drop_write(nd.mnt);
 	exit2:
 		dput(dentry);
 	}
diff -puN ipc/mqueue.c~r-o-bind-mounts-elevate-mnt-writers-for-vfs_unlink-callers ipc/mqueue.c
--- linux-2.6.git/ipc/mqueue.c~r-o-bind-mounts-elevate-mnt-writers-for-vfs_unlink-callers	2008-02-08 13:04:50.000000000 -0800
+++ linux-2.6.git-dave/ipc/mqueue.c	2008-02-08 13:04:50.000000000 -0800
@@ -743,8 +743,11 @@ asmlinkage long sys_mq_unlink(const char
 	inode = dentry->d_inode;
 	if (inode)
 		atomic_inc(&inode->i_count);
-
+	err = mnt_want_write(mqueue_mnt);
+	if (err)
+		goto out_err;
 	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
+	mnt_drop_write(mqueue_mnt);
 out_err:
 	dput(dentry);
 
_
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