[RFC] change of lookup() method.
Alexander Viro (viro@math.psu.edu)
Sat, 10 Apr 1999 12:44:19 -0400 (EDT)
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?
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