Date: Mon, 30 Mar 2009 11:31:43 -0400 From: John Baldwin <jhb@FreeBSD.org> To: Tim Kientzle <kientzle@FreeBSD.org> Cc: Pawel Jakub Dawidek <pjd@FreeBSD.org>, Attilio Rao <attilio@FreeBSD.org>, "freebsd-current@freebsd.org" <freebsd-current@FreeBSD.org>, Mark Powell <M.S.Powell@salford.ac.uk>, Anonymous <swell.k@gmail.com>, Peter Schuller <peter.schuller@infidyne.com> Subject: Re: repeatable ZFS panic: share->excl Message-ID: <200903301131.44164.jhb@freebsd.org> In-Reply-To: <49CFA1D9.1020604@freebsd.org> References: <20090312175345.Y80227@rust.salford.ac.uk> <20090317070440.GE2012@garage.freebsd.pl> <49CFA1D9.1020604@freebsd.org>
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On Sunday 29 March 2009 12:29:13 pm Tim Kientzle wrote: > Pawel Jakub Dawidek wrote: > > On Fri, Mar 13, 2009 at 02:08:03PM -0400, John Baldwin wrote: > >> John Baldwin wrote: > >>> 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. > >> So lulf@ reports success with this patch. Pawel, can you review it? > > > > Yes, it works for me too and looks good. The only thing we need to > > change is to check for error beeing 0 before unlocking the vnode. > > The zfs_make_xattrdir() function can still return with EIO, so I'd add > > something like this: > > > > if (error == 0) > > VOP_UNLOCK(*xvpp, 0); > > > > Thank you John for spending time on tracking this one down. > > Any estimate on when this can be committed? > > I'm waiting to re-enable the extended attribute > archiving support in tar until this is fixed. Err, it went into the tree a while ago: Author: jhb Date: Wed Mar 18 16:19:44 2009 New Revision: 189967 URL: http://svn.freebsd.org/changeset/base/189967 Log: The zfs_get_xattrdir() function is used to find the extended attribute directory for a znode. When the directory already exists, it returns a referenced but unlocked vnode. When a directory does not yet exist, it calls zfs_make_xattrdir() to create a new one. zfs_make_xattrdir() returns the vnode both referenced and and locked and zfs_get_xattrdir() was leaking this vnode lock to its callers. Fix this by dropping the vnode lock if zfs_make_xattrdir() successfully creates a new extended attribute directory. Reviewed by: pjd -- John Baldwin
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