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Bruce Fields" To: Sasha Levin Cc: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Trond Myklebust Subject: Re: [PATCH AUTOSEL for 4.4 19/35] nfsd: Ensure we don't recognise lock stateids after freeing them Message-ID: <20180124154827.GD31619@parsley.fieldses.org> References: <20180124041645.32420-1-alexander.levin@microsoft.com> <20180124041645.32420-19-alexander.levin@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180124041645.32420-19-alexander.levin@microsoft.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Ditto.--b. On Wed, Jan 24, 2018 at 04:17:02AM +0000, Sasha Levin wrote: > From: Trond Myklebust > > [ Upstream commit 659aefb68eca28ba9aa482a9fc64de107332e256 ] > > In order to deal with lookup races, nfsd4_free_lock_stateid() needs > to be able to signal to other stateful functions that the lock stateid > is no longer valid. Right now, nfsd_lock() will check whether or not an > existing stateid is still hashed, but only in the "new lock" path. > > To ensure the stateid invalidation is also recognised by the "existing lock" > path, and also by a second call to nfsd4_free_lock_stateid() itself, we can > change the type to NFS4_CLOSED_STID under the stp->st_mutex. > > Signed-off-by: Trond Myklebust > Signed-off-by: J. Bruce Fields > Signed-off-by: Sasha Levin > --- > fs/nfsd/nfs4state.c | 19 ++++++++----------- > 1 file changed, 8 insertions(+), 11 deletions(-) > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index d31b6cdefb9d..439f01a0bc49 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -4934,7 +4934,9 @@ nfsd4_free_lock_stateid(stateid_t *stateid, struct nfs4_stid *s) > struct nfs4_ol_stateid *stp = openlockstateid(s); > __be32 ret; > > - mutex_lock(&stp->st_mutex); > + ret = nfsd4_lock_ol_stateid(stp); > + if (ret) > + goto out_put_stid; > > ret = check_stateid_generation(stateid, &s->sc_stateid, 1); > if (ret) > @@ -4945,11 +4947,13 @@ nfsd4_free_lock_stateid(stateid_t *stateid, struct nfs4_stid *s) > lockowner(stp->st_stateowner))) > goto out; > > + stp->st_stid.sc_type = NFS4_CLOSED_STID; > release_lock_stateid(stp); > ret = nfs_ok; > > out: > mutex_unlock(&stp->st_mutex); > +out_put_stid: > nfs4_put_stid(s); > return ret; > } > @@ -5489,6 +5493,8 @@ find_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp) > lockdep_assert_held(&clp->cl_lock); > > list_for_each_entry(lst, &lo->lo_owner.so_stateids, st_perstateowner) { > + if (lst->st_stid.sc_type != NFS4_LOCK_STID) > + continue; > if (lst->st_stid.sc_file == fp) { > atomic_inc(&lst->st_stid.sc_count); > return lst; > @@ -5563,7 +5569,6 @@ lookup_or_create_lock_state(struct nfsd4_compound_state *cstate, > struct nfs4_lockowner *lo; > struct nfs4_ol_stateid *lst; > unsigned int strhashval; > - bool hashed; > > lo = find_lockowner_str(cl, &lock->lk_new_owner); > if (!lo) { > @@ -5586,15 +5591,7 @@ retry: > goto out; > } > > - mutex_lock(&lst->st_mutex); > - > - /* See if it's still hashed to avoid race with FREE_STATEID */ > - spin_lock(&cl->cl_lock); > - hashed = !list_empty(&lst->st_perfile); > - spin_unlock(&cl->cl_lock); > - > - if (!hashed) { > - mutex_unlock(&lst->st_mutex); > + if (nfsd4_lock_ol_stateid(lst) != nfs_ok) { > nfs4_put_stid(&lst->st_stid); > goto retry; > } > -- > 2.11.0