On Tue, 2019-03-12 at 20:12 +0000, Trond Myklebust wrote:
> On Tue, 2019-03-12 at 20:04 +0000, Schumaker, Anna wrote:
> > Hi Trond,
> >
> > I'm seeing a hang when testing xfstests generic/013 on v4.1 with pNFS
> > after this
> > patch:
> >
> > On Wed, 2018-09-05 at 14:07 -0400, Trond Myklebust wrote:
> > > If someone interrupts a wait on one or more outstanding layoutgets
> > > in
> > > pnfs_update_layout() then return the ERESTARTSYS/EINTR error.
> > >
> > > Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> > > ---
> > > fs/nfs/pnfs.c | 26 ++++++++++++++++----------
> > > 1 file changed, 16 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> > > index e8f232de484f..7d9a51e6b847 100644
> > > --- a/fs/nfs/pnfs.c
> > > +++ b/fs/nfs/pnfs.c
> > > @@ -1740,16 +1740,16 @@ static bool pnfs_within_mdsthreshold(struct
> > > nfs_open_context *ctx,
> > > return ret;
> > > }
> > >
> > > -static bool pnfs_prepare_to_retry_layoutget(struct pnfs_layout_hdr
> > > *lo)
> > > +static int pnfs_prepare_to_retry_layoutget(struct pnfs_layout_hdr
> > > *lo)
> > > {
> > > /*
> > > * send layoutcommit as it can hold up layoutreturn due to lseg
> > > * reference
> > > */
> > > pnfs_layoutcommit_inode(lo->plh_inode, false);
> > > - return !wait_on_bit_action(&lo->plh_flags, NFS_LAYOUT_RETURN,
> > > + return wait_on_bit_action(&lo->plh_flags, NFS_LAYOUT_RETURN,
> > > nfs_wait_bit_killable,
> > > - TASK_UNINTERRUPTIBLE);
> > > + TASK_KILLABLE);
> > > }
> > >
> > > static void nfs_layoutget_begin(struct pnfs_layout_hdr *lo)
> > > @@ -1830,7 +1830,9 @@ pnfs_update_layout(struct inode *ino,
> > > }
> > >
> > > lookup_again:
> > > - nfs4_client_recover_expired_lease(clp);
> > > + lseg = ERR_PTR(nfs4_client_recover_expired_lease(clp));
> > > + if (IS_ERR(lseg))
> > > + goto out;
> > > first = false;
> > > spin_lock(&ino->i_lock);
> > > lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
> > > @@ -1863,9 +1865,9 @@ pnfs_update_layout(struct inode *ino,
> > > if (list_empty(&lo->plh_segs) &&
> > > atomic_read(&lo->plh_outstanding) != 0) {
> > > spin_unlock(&ino->i_lock);
> > > - if (wait_var_event_killable(&lo->plh_outstanding,
> > > - atomic_read(&lo-
> > > > plh_outstanding) == 0
> > > - || !list_empty(&lo->plh_segs)))
> > > + lseg = ERR_PTR(wait_var_event_killable(&lo-
> > > > plh_outstanding,
> > > + atomic_read(&lo-
> > > > plh_outstanding)));
> > > + if (IS_ERR(lseg) || !list_empty(&lo->plh_segs))
> >
> > Was dropping the "== 0" condition attached to the atomic_read() here
> > a mistake?
> > I think what's happening is that my client is waiting for
> > plh_outstanding to be
> > anything other than 0 when there isn't any work left to do.
>
> Yes. That's a bug. How about the following patch?
This patch works for me, but for some reason doing "!atomic_read()" takes 8
minutes longer to complete compared to doing "atomic_read() == 0". I have not
run this multiple times to confirm that it's always the case.
Anna
>
> 8<---------------------------------------------------
> From 400417b05f3ec0531544ca5f94e64d838d8b8849 Mon Sep 17 00:00:00 2001
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> Date: Tue, 12 Mar 2019 16:04:51 -0400
> Subject: [PATCH] pNFS: Fix a typo in pnfs_update_layout
>
> We're supposed to wait for the outstanding layout count to go to zero,
> but that got lost somehow.
>
> Fixes: d03360aaf5cca ("pNFS: Ensure we return the error if someone...")
> Reported-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfs/pnfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index 8247bd1634cb..7066cd7c7aff 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -1889,7 +1889,7 @@ pnfs_update_layout(struct inode *ino,
> atomic_read(&lo->plh_outstanding) != 0) {
> spin_unlock(&ino->i_lock);
> lseg = ERR_PTR(wait_var_event_killable(&lo->plh_outstanding,
> - atomic_read(&lo->plh_outstanding)));
> + !atomic_read(&lo->plh_outstanding)));
> if (IS_ERR(lseg) || !list_empty(&lo->plh_segs))
> goto out_put_layout_hdr;
> pnfs_put_layout_hdr(lo);
> --
> 2.20.1
>
> --
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@xxxxxxxxxxxxxxx
>
>
