Cache root in nameidata

New field: nd->root.  When pathname resolution wants to know the root,
check if nd->root.mnt is non-NULL; use nd->root if it is, otherwise
copy current->fs->root there.  After path_walk() is finished, we check
if we'd got a cached value in nd->root and drop it.  Before calling
path_walk() we should either set nd->root.mnt to NULL *or* copy (and
pin down) some path to nd->root.  In the latter case we won't be
looking at current->fs->root at all.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/namei.h b/include/linux/namei.h
index 518098fe63af..325dd3ad39a0 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -18,6 +18,7 @@ enum { MAX_NESTED_LINKS = 8 };
 struct nameidata {
         struct path     path;
         struct qstr     last;
+        struct path     root;
         unsigned int    flags;
         int             last_type;
         unsigned        depth;