[PATCH] r/o bind mounts: elevate write count for rmdir and unlink.

Elevate the write count during the vfs_rmdir() and vfs_unlink().

[AV: merged rmdir and unlink parts, added missing pieces in nfsd]

Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/namei.c b/fs/namei.c
index a1f8bbb..89ef317 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2190,7 +2190,12 @@ static long do_rmdir(int dfd, const char __user *pathname)
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
 		goto exit2;
+	error = mnt_want_write(nd.path.mnt);
+	if (error)
+		goto exit3;
 	error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+	mnt_drop_write(nd.path.mnt);
+exit3:
 	dput(dentry);
 exit2:
 	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
@@ -2271,7 +2276,11 @@ static long do_unlinkat(int dfd, const char __user *pathname)
 		inode = dentry->d_inode;
 		if (inode)
 			atomic_inc(&inode->i_count);
+		error = mnt_want_write(nd.path.mnt);
+		if (error)
+			goto exit2;
 		error = vfs_unlink(nd.path.dentry->d_inode, dentry);
+		mnt_drop_write(nd.path.mnt);
 	exit2:
 		dput(dentry);
 	}