A root directory is a directory that has itself as the parent.
There is only one such directory, but for chroot support we will want to
stop path resolution at a non-root directory as well.
We do this by giving struct nameidata a d_root field, which serves as a
root directory for the lookup. As we initialize it to the global root
directory, this introduces no functional change.
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
fs/fs.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/fs/fs.c b/fs/fs.c
index 54f38aa2e63b..7fc638451f13 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -1623,6 +1623,7 @@ struct nameidata {
} *stack, internal[EMBEDDED_LEVELS];
struct filename *name;
struct inode *link_inode;
+ struct dentry *d_root;
};
struct filename {
@@ -1635,6 +1636,7 @@ static void set_nameidata(struct nameidata *p, struct filename *name)
p->stack = p->internal;
p->name = name;
p->total_link_count = 0;
+ p->d_root = d_root;
}
static void path_get(const struct path *path)
@@ -1820,16 +1822,16 @@ static int lookup_fast(struct nameidata *nd, struct path *path)
* Return 1 if we went up a level and 0 if we were already at the
* root.
*/
-static int follow_up(struct path *path)
+static int follow_up(struct nameidata *nd)
{
- struct vfsmount *parent, *mnt = path->mnt;
+ struct path *path = &nd->path;
+ struct vfsmount *mnt = path->mnt;
struct dentry *mountpoint;
- parent = mnt->parent;
- if (parent == mnt)
+ if (nd->d_root == path->dentry)
return 0;
- mntget(parent);
+ mntget(mnt->parent);
mountpoint = dget(mnt->mountpoint);
dput(path->dentry);
path->dentry = mountpoint;
@@ -1871,7 +1873,7 @@ static int follow_dotdot(struct nameidata *nd)
break;
}
- if (!follow_up(&nd->path))
+ if (!follow_up(nd))
break;
}
--
2.39.2
