As announced some weeks ago here comes the API change to VOP_LOOKUP:
Change vnode operation lookup to return the resulting vnode *vpp locked.
Change cache_lookup() to return an unlocked vnode.
The fast path through the name cache doesn't add unlock/locks.
Most file systems now do this on cache miss:
<lookup the inode number>
if (ISDOTDOT)
VOP_UNLOCK(dvp);
VFS_VGET(mp, ino, &vpp);
if (ISDOTDOT)
vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY);
VOP_UNLOCK(*vpp);
return *vpp;
This lock/unlock dance will go once VFS_VGET gets replaced or enhanced
with a vnode/inode hash list that looks up vnodes without locking them.
Diff at: http://www.netbsd.org/~hannken/vnode-pass2b-1.diff
Comments or objections anyone?
--
J. Hannken-Illjes - [email protected] - TU Braunschweig (Germany)
