Change vnode operation lookup to return the resulting vnode *vpp unlocked.
Change cache_lookup() to return an unlocked vnode. Discussed on tech-kern@
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# $NetBSD: vnode_if.src,v 1.65 2014/01/23 10:11:55 hannken Exp $
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# $NetBSD: vnode_if.src,v 1.66 2014/02/07 15:26:42 hannken Exp $
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#
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# Copyright (c) 1992, 1993
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# The Regents of the University of California. All rights reserved.
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@ -61,27 +61,17 @@ vop_bwrite {
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#
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#% lookup dvp L L L
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#% lookup vpp - L -
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#% lookup vpp - U -
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#
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# XXX - the lookup locking protocol defies simple description.
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# Note especially that *vpp may equal dvp.
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#
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# More details:
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# There are three types of lookups: ".", ".." (ISDOTDOT), and other.
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# On successful lookup of ".", a reference is added to dvp, and it
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# is returned in *vpp.
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# To look up ISDOTDOT, dvp is unlocked, the ".." node is locked, and
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# then dvp is relocked. This preserves the protocol of always
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# locking nodes from root ("/") downward and prevents deadlock.
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# Other lookups find the named node (creating the vnode if needed) and
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# return it, locked, in *vpp.
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# All lookups find the named node (creating the vnode if needed) and
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# return it, referenced and unlocked, in *vpp.
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# On failure, *vpp is NULL, and *dvp is left locked.
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#
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# *vpp is always locked on return if the operation succeeds.
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# Typically, if *vpp == dvp, you need to release twice, but
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# unlock only once.
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#
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vop_lookup {
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VERSION 2
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IN struct vnode *dvp;
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OUT WILLMAKE struct vnode **vpp;
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IN struct componentname *cnp;
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