Date: Thu, 20 Nov 2008 17:26:43 -0500 From: John Baldwin <jhb@freebsd.org> To: "Attilio Rao" <attilio@freebsd.org> Cc: scottl@freebsd.org, current@freebsd.org Subject: Re: [PATCH] Make udf(4) MPSAFE and use shared lookups Message-ID: <200811201726.43467.jhb@freebsd.org> In-Reply-To: <3bbf2fe10811201402x4eb6fa70i398bfb1402792fef@mail.gmail.com> References: <200811201627.58289.jhb@freebsd.org> <3bbf2fe10811201402x4eb6fa70i398bfb1402792fef@mail.gmail.com>
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On Thursday 20 November 2008 05:02:29 pm Attilio Rao wrote: > 2008/11/20, John Baldwin <jhb@freebsd.org>: > > So this patch is fairly minimal since udf(4) is currently read-only. The > > changes include: > > > > * Set VV_ROOT in udf_vget() if we ever return a vnode instead of doing it only > > in udf_root(). This matches the behavior of other operating systems and > > correctly tags the root vnode with VV_ROOT in the unlikely case that we > > create the vnode during a call to ufs_vget() that does not come from > > ufs_root(). > > * If the hash lookup in ufs_vget() fails, ensure an exclusive vnode lock is > > used while creating the new vnode (same as UFS). > > * Allow lock recursion (XXX: not really sure this is needed actually). > > * Allow shared vnode locks on non-fifos. > > * Honor the requested locking flags (shared vs exclusive) instead of always > > using exclusive vnode locks during a lookup operation. > > * Handle "." lookups the same way other filesystems do by just bumping the > > reference on 'dvp' rather than calling udf_vget(). > > > > http://www.FreeBSD.org/~jhb/patches/udf_mpsafe.patch > > @@ -589,6 +582,22 @@ > if (error || *vpp != NULL) > return (error); > > + /* > + * We must promote to an exclusive lock for vnode creation. This > + * can happen if lookup is passed LOCKSHARED. > + */ > + if ((flags & LK_TYPE_MASK) == LK_SHARED) { > + flags &= ~LK_TYPE_MASK; > + flags |= LK_EXCLUSIVE; > + } > + > > On -CURRENT, operations are bitwise (differently from 7.x and such). > What you want to do is just: > flag = (flag & ~LK_SHARED) | LK_EXCLUSIVE; I just copied and pasted from UFS in HEAD. -- John Baldwin
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