Folks, right now we have ->lookup() returning 0 in case of success (in which case the argument gets hashed and becomes either positive or negative) or a negative integer in case of error (too long name, etc.). Proposed change: make it return a pointer to struct dentry. Semantics: NULL - old one would return 0. ERR_PTR(-foo) - old one would return foo. normal pointer - we got an alias dentry; act as if you've passed it to ->lookup() and it returned 0. (notice that it is binary compatible with the current variant, i.e. it doesn't break existing modules). More on the last case: it allows to reduce the cruft in VFAT *and* gives us portalfs almost for free. Impact on the existing filesystems: none for already compiled modules, to ensure clean compile - trivial change of int foo_lookup(struct dentry *dentry) to struct dentry *foo_lookup(struct dentry *dentry), along with replacing return foo; with return ERR_PTR(foo); in said functions. Comments?