Date: Sun, 30 Dec 2012 16:58:13 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Ronald Klop <ronald-freebsd8@klop.yi.org> Cc: gber@freebsd.org, cognet@freebsd.org, fs@freebsd.org Subject: Re: Nandfs use of MNT_VNODE_FOREACH Message-ID: <20121230145813.GI82219@kib.kiev.ua> In-Reply-To: <op.wp4w3fj58527sy@pinky> References: <20121227230223.GN82219@kib.kiev.ua> <op.wp4w3fj58527sy@pinky>
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On Sun, Dec 30, 2012 at 03:55:53PM +0100, Ronald Klop wrote:
> I'm building a patched kernel for my sheevaplug now which reads the kerne=
l =20
> from nand and has / mounted from nandfs.
> What should be tested specifically? Just booting from it?
I suspect that a writeable mount with some / enough write activity
is good for the test.
Thank you.
>=20
> Ronald.
>=20
> On Fri, 28 Dec 2012 00:02:23 +0100, Konstantin Belousov =20
> <kostikbel@gmail.com> wrote:
>=20
> > I took a look at removing MNT_VNODE_FOREACH interface in the HEAD,
> > and apparently we still have one user of the said interface, probably,
> > due to cross-commits.
> >
> > Namely, nandfs utilizes the interface. First, it is obsoleted and
> > is going to be removed. Second, I believe that MNT_VNODE_FOREACH_ACTIVE
> > would be better choice there, because intent of the loop is to do
> > something with each dirty vnode, and dirty vnode must be active, because
> > there are dirty buffers attached to it.
> >
> > That said, use of vget(LK_RETRY) and immediate check for VI_DOOMED
> > is not useful, I removed the LK_RETRY from the lockflags. Another issue=
=20
> > is
> > that intent was to avoid sleep for locked vnode, but the check is racy.
> > I used LK_NOWAIT instead.
> >
> > Check for mnt_syncer is also usually done as vp->v_type =3D=3D VNON, but
> > lets postpone this.
> >
> > Could someone who uses the filesystem test the patch below, please ?
> >
> > diff --git a/sys/fs/nandfs/nandfs_segment.c =20
> > b/sys/fs/nandfs/nandfs_segment.c
> > index 836bead..a73b7f2 100644
> > --- a/sys/fs/nandfs/nandfs_segment.c
> > +++ b/sys/fs/nandfs/nandfs_segment.c
> > @@ -481,36 +481,20 @@ nandfs_iterate_dirty_vnodes(struct mount *mp, =20
> > struct nandfs_seginfo *seginfo)
> > int error, lockreq, update;
> > td =3D curthread;
> > - lockreq =3D LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY;
> > + lockreq =3D LK_EXCLUSIVE | LK_INTERLOCK;
> > - MNT_ILOCK(mp);
> > -
> > - MNT_VNODE_FOREACH(vp, mp, mvp) {
> > + MNT_VNODE_FOREACH_ACTIVE(vp, mp, mvp) {
> > update =3D 0;
> > if (mp->mnt_syncer =3D=3D vp)
> > continue;
> > - if (VOP_ISLOCKED(vp))
> > - continue;
> > -
> > - VI_LOCK(vp);
> > - MNT_IUNLOCK(mp);
> > - if (vp->v_iflag & VI_DOOMED) {
> > + if (VOP_ISLOCKED(vp)) {
> > VI_UNLOCK(vp);
> > - MNT_ILOCK(mp);
> > - continue;
> > - }
> > -
> > - if ((error =3D vget(vp, lockreq, td)) !=3D 0) {
> > - MNT_ILOCK(mp);
> > continue;
> > }
> > - if (vp->v_iflag & VI_DOOMED) {
> > - vput(vp);
> > - MNT_ILOCK(mp);
> > + if (vget(vp, lockreq, td) !=3D 0)
> > continue;
> > - }
> > nandfs_node =3D VTON(vp);
> > if (nandfs_node->nn_flags & IN_MODIFIED) {
> > @@ -532,12 +516,8 @@ nandfs_iterate_dirty_vnodes(struct mount *mp, =20
> > struct nandfs_seginfo *seginfo)
> > if (update)
> > nandfs_node_update(nandfs_node);
> > -
> > - MNT_ILOCK(mp);
> > }
> > - MNT_IUNLOCK(mp);
> > -
> > return (0);
> > }
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