Hi, all:

I am studying the dcache in VFS recently . I've found that hlist of dcache is already protected by RCU in

 __d_lookup.Is it necessary  for the function -- d_lookup using sequence lock to protect the hlist again?

struct dentry * d_lookup(struct dentry * parent, struct qstr * name)

{

struct dentry * dentry = NULL;

unsigned long seq;

        do {

                seq = read_seqbegin(&rename_lock);

                dentry = __d_lookup(parent, name);

                if (dentry)

break;

} while (read_seqretry(&rename_lock, seq));

return dentry;

}

Thanks in advance

--------------------------------

Rock Lee