Date: Fri, 13 Mar 2009 13:29:37 -0400 From: John Baldwin <jhb@FreeBSD.org> To: Attilio Rao <attilio@FreeBSD.org> Cc: Pawel Jakub Dawidek <pjd@FreeBSD.org>, Mark Powell <M.S.Powell@salford.ac.uk>, John Baldwin <jhb@FreeBSD.org>, "freebsd-current@freebsd.org" <freebsd-current@FreeBSD.org>, Tim Kientzle <kientzle@FreeBSD.org>, Anonymous <swell.k@gmail.com>, Peter Schuller <peter.schuller@infidyne.com> Subject: Re: repeatable ZFS panic: share->excl Message-ID: <49BA9801.5080505@FreeBSD.org> In-Reply-To: <3bbf2fe10903122156u650417f0s5c49b68bdf4ffa07@mail.gmail.com> References: <20090312175345.Y80227@rust.salford.ac.uk> <20090312191333.GA97342@hyperion.scode.org> <49B97617.8010709@freebsd.org> <86r6124f2v.fsf@gmail.com> <3bbf2fe10903122035i20b2767cod2322c39c6f850ee@mail.gmail.com> <29C8FA04-D5B1-49B7-ACF0-4185537367B0@baldwin.cx> <3bbf2fe10903122156u650417f0s5c49b68bdf4ffa07@mail.gmail.com>
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Attilio Rao wrote: > 2009/3/13, John Baldwin <john@baldwin.cx>: >> This is similar to the patch I've asked lulf@ to test except that >> it is longer and I fix a bug where zfs_lookup() can leak a vnode >> lock if the access check fails. :-) The last one I sent to lulf@ >> is at www.FreeBSD.org/~jhb/patches/zfs_ea.patch. > > I really thought zfs_lookup() was returning the lock held as a > feature assming no LOCKLEAF. Is that a bug instead? Yes, I think that is the real bug. Looking at this further I think zfs_get_xattrdir() will return the vnode locked if it has to create a new node via zfs_make_attrdir() but only returns it held and unlocked if it finds an existing one. So my new patch is to just fix zfs_get_xattrdir() to unlock the vnode if it creates a new one like so: (Sorry, TBird is probably going to butcher all the whitespace): --- //depot/user/jhb/lock/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_dir.c +++ /Users/jhb/work/p4/lock/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_dir.c @@ -940,6 +940,7 @@ /* NB: we already did dmu_tx_wait() if necessary */ goto top; } + VOP_UNLOCK(*xvpp, 0); return (error); } A non-butchered version is at www.FreeBSD.org/~jhb/patches/zfs_ea.patch. -- John Baldwin
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