On Sun, 10 Mar 2024, Chuck Lever wrote:
> On Tue, Mar 05, 2024 at 09:45:22AM +1100, NeilBrown wrote:
> > Currently find_openstateowner_str looks are done both in
> > nfsd4_process_open1() and alloc_init_open_stateowner() - the latter
> > possibly being a surprise based on its name.
> >
> > It would be easier to follow, and more conformant to common patterns, if
> > the lookup was all in the one place.
> >
> > So replace alloc_init_open_stateowner() with
> > find_or_alloc_open_stateowner() and use the latter in
> > nfsd4_process_open1() without any calls to find_openstateowner_str().
> >
> > This means all finds are find_openstateowner_str_locked() and
> > find_openstateowner_str() is no longer needed. So discard
> > find_openstateowner_str() and rename find_openstateowner_str_locked() to
> > find_openstateowner_str().
> >
> > Signed-off-by: NeilBrown <neilb@xxxxxxx>
> > ---
> > fs/nfsd/nfs4state.c | 93 +++++++++++++++++++--------------------------
> > 1 file changed, 40 insertions(+), 53 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index b9b3a2601675..0c1058e8cc4b 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -541,7 +541,7 @@ same_owner_str(struct nfs4_stateowner *sop, struct xdr_netobj *owner)
> > }
> >
> > static struct nfs4_openowner *
> > -find_openstateowner_str_locked(unsigned int hashval, struct nfsd4_open *open,
> > +find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open,
> > struct nfs4_client *clp)
> > {
> > struct nfs4_stateowner *so;
> > @@ -558,18 +558,6 @@ find_openstateowner_str_locked(unsigned int hashval, struct nfsd4_open *open,
> > return NULL;
> > }
> >
> > -static struct nfs4_openowner *
> > -find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open,
> > - struct nfs4_client *clp)
> > -{
> > - struct nfs4_openowner *oo;
> > -
> > - spin_lock(&clp->cl_lock);
> > - oo = find_openstateowner_str_locked(hashval, open, clp);
> > - spin_unlock(&clp->cl_lock);
> > - return oo;
> > -}
> > -
> > static inline u32
> > opaque_hashval(const void *ptr, int nbytes)
> > {
> > @@ -4855,34 +4843,46 @@ nfsd4_find_and_lock_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
> > }
> >
> > static struct nfs4_openowner *
> > -alloc_init_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
> > - struct nfsd4_compound_state *cstate)
> > +find_or_alloc_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
> > + struct nfsd4_compound_state *cstate)
> > {
> > struct nfs4_client *clp = cstate->clp;
> > - struct nfs4_openowner *oo, *ret;
> > + struct nfs4_openowner *oo, *new = NULL;
> >
> > - oo = alloc_stateowner(openowner_slab, &open->op_owner, clp);
> > - if (!oo)
> > - return NULL;
> > - oo->oo_owner.so_ops = &openowner_ops;
> > - oo->oo_owner.so_is_open_owner = 1;
> > - oo->oo_owner.so_seqid = open->op_seqid;
> > - oo->oo_flags = 0;
> > - if (nfsd4_has_session(cstate))
> > - oo->oo_flags |= NFS4_OO_CONFIRMED;
> > - oo->oo_time = 0;
> > - oo->oo_last_closed_stid = NULL;
> > - INIT_LIST_HEAD(&oo->oo_close_lru);
> > - spin_lock(&clp->cl_lock);
> > - ret = find_openstateowner_str_locked(strhashval, open, clp);
> > - if (ret == NULL) {
> > - hash_openowner(oo, clp, strhashval);
> > - ret = oo;
> > - } else
> > - nfs4_free_stateowner(&oo->oo_owner);
> > + while (1) {
> > + spin_lock(&clp->cl_lock);
> > + oo = find_openstateowner_str(strhashval, open, clp);
> > + if (oo && !(oo->oo_flags & NFS4_OO_CONFIRMED)) {
> > + /* Replace unconfirmed owners without checking for replay. */
> > + release_openowner(oo);
> > + oo = NULL;
> > + }
> > + if (oo) {
> > + spin_unlock(&clp->cl_lock);
> > + if (new)
> > + nfs4_free_stateowner(&new->oo_owner);
> > + return oo;
> > + }
> > + if (new) {
> > + hash_openowner(new, clp, strhashval);
> > + spin_unlock(&clp->cl_lock);
> > + return new;
> > + }
> > + spin_unlock(&clp->cl_lock);
> >
> > - spin_unlock(&clp->cl_lock);
> > - return ret;
> > + new = alloc_stateowner(openowner_slab, &open->op_owner, clp);
> > + if (!new)
> > + return NULL;
> > + new->oo_owner.so_ops = &openowner_ops;
> > + new->oo_owner.so_is_open_owner = 1;
> > + new->oo_owner.so_seqid = open->op_seqid;
> > + new->oo_flags = 0;
> > + if (nfsd4_has_session(cstate))
> > + new->oo_flags |= NFS4_OO_CONFIRMED;
> > + new->oo_time = 0;
> > + new->oo_last_closed_stid = NULL;
> > + INIT_LIST_HEAD(&new->oo_close_lru);
> > + }
> > }
> >
> > static struct nfs4_ol_stateid *
> > @@ -5331,28 +5331,15 @@ nfsd4_process_open1(struct nfsd4_compound_state *cstate,
> > clp = cstate->clp;
> >
> > strhashval = ownerstr_hashval(&open->op_owner);
> > - oo = find_openstateowner_str(strhashval, open, clp);
> > + oo = find_or_alloc_open_stateowner(strhashval, open, cstate);
> > open->op_openowner = oo;
> > if (!oo)
> > - goto new_owner;
> > - if (!(oo->oo_flags & NFS4_OO_CONFIRMED)) {
> > - /* Replace unconfirmed owners without checking for replay. */
> > - release_openowner(oo);
> > - open->op_openowner = NULL;
> > - goto new_owner;
> > - }
> > + return nfserr_jukebox;
> > nfsd4_cstate_assign_replay(cstate, &oo->oo_owner);
> > status = nfsd4_check_seqid(cstate, &oo->oo_owner, open->op_seqid);
> > if (status)
> > return status;
> > - goto alloc_stateid;
> > -new_owner:
> > - oo = alloc_init_open_stateowner(strhashval, open, cstate);
> > - if (oo == NULL)
> > - return nfserr_jukebox;
> > - open->op_openowner = oo;
> > - nfsd4_cstate_assign_replay(cstate, &oo->oo_owner);
> > -alloc_stateid:
> > +
> > open->op_stp = nfs4_alloc_open_stateid(clp);
> > if (!open->op_stp)
> > return nfserr_jukebox;
> > --
> > 2.43.0
> >
>
> While running the NFSv4.0 pynfs tests with KASAN and lock debugging
> enabled, I get a number of CPU soft lockup warnings on the test
> server and then it wedges hard. I bisected to this patch.
Almost certainly this is the problem Dan Carpenter found and reported.
>
> Because we are just a day shy of the v6.9 merge window, I'm going to
> drop these four patches for v6.9. We can try them again for v6.10.
I'll post a revised version of this patch - it shouldn't affect the
subsequent patches (though I can resend them to if/when you want).
Up to you when it lands of course.
NeilBrown
