[PATCH] r/o bind mounts: get write access for vfs_rename() callers

This also uses the little helper in the NFS code to make an if() a little bit
less ugly.  We introduced the helper at the beginning of the series.

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, 4 insertions, 0 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 00df735fb509..83c843b3fea3 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2718,8 +2718,12 @@ static int do_rename(int olddfd, const char *oldname,
         if (new_dentry == trap)
                 goto exit5;
 
+        error = mnt_want_write(oldnd.path.mnt);
+        if (error)
+                goto exit5;
         error = vfs_rename(old_dir->d_inode, old_dentry,
                                    new_dir->d_inode, new_dentry);
+        mnt_drop_write(oldnd.path.mnt);
 exit5:
         dput(new_dentry);
 exit4: