diff options
| author | Jeff Layton <jlayton@poochiereds.net> | 2015-08-24 12:41:48 -0400 |
|---|---|---|
| committer | J. Bruce Fields <bfields@redhat.com> | 2015-08-31 16:32:16 -0400 |
| commit | 3fcbbd244ed1d20dc0eb7d48d729503992fa9b7d (patch) | |
| tree | ac901181a7228f5534a4b013c522cc2064beba8d /fs/nfsd/nfs4state.c | |
| parent | e85687393f3ee0a77ccca016f903d1558bb69258 (diff) | |
nfsd: ensure that delegation stateid hash references are only put once
It's possible that a DELEGRETURN could race with (e.g.) client expiry,
in which case we could end up putting the delegation hash reference more
than once.
Have unhash_delegation_locked return a bool that indicates whether it
was already unhashed. In the case of destroy_delegation we only
conditionally put the hash reference if that returns true.
The other callers of unhash_delegation_locked call it while walking
list_heads that shouldn't yet be detached. If we find that it doesn't
return true in those cases, then throw a WARN_ON as that indicates that
we have a partially hashed delegation, and that something is likely very
wrong.
Tested-by: Andrew W Elble <aweits@rit.edu>
Tested-by: Anna Schumaker <Anna.Schumaker@netapp.com>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/nfsd/nfs4state.c')
| -rw-r--r-- | fs/nfsd/nfs4state.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index f318e706cb35..416f32e34a33 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -777,13 +777,16 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp) list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations); } -static void +static bool unhash_delegation_locked(struct nfs4_delegation *dp) { struct nfs4_file *fp = dp->dl_stid.sc_file; lockdep_assert_held(&state_lock); + if (list_empty(&dp->dl_perfile)) + return false; + dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID; /* Ensure that deleg break won't try to requeue it */ ++dp->dl_time; @@ -792,16 +795,21 @@ unhash_delegation_locked(struct nfs4_delegation *dp) list_del_init(&dp->dl_recall_lru); list_del_init(&dp->dl_perfile); spin_unlock(&fp->fi_lock); + return true; } static void destroy_delegation(struct nfs4_delegation *dp) { + bool unhashed; + spin_lock(&state_lock); - unhash_delegation_locked(dp); + unhashed = unhash_delegation_locked(dp); spin_unlock(&state_lock); - put_clnt_odstate(dp->dl_clnt_odstate); - nfs4_put_deleg_lease(dp->dl_stid.sc_file); - nfs4_put_stid(&dp->dl_stid); + if (unhashed) { + put_clnt_odstate(dp->dl_clnt_odstate); + nfs4_put_deleg_lease(dp->dl_stid.sc_file); + nfs4_put_stid(&dp->dl_stid); + } } static void revoke_delegation(struct nfs4_delegation *dp) @@ -1730,7 +1738,7 @@ __destroy_client(struct nfs4_client *clp) spin_lock(&state_lock); while (!list_empty(&clp->cl_delegations)) { dp = list_entry(clp->cl_delegations.next, struct nfs4_delegation, dl_perclnt); - unhash_delegation_locked(dp); + WARN_ON(!unhash_delegation_locked(dp)); list_add(&dp->dl_recall_lru, &reaplist); } spin_unlock(&state_lock); @@ -4357,7 +4365,7 @@ nfs4_laundromat(struct nfsd_net *nn) new_timeo = min(new_timeo, t); break; } - unhash_delegation_locked(dp); + WARN_ON(!unhash_delegation_locked(dp)); list_add(&dp->dl_recall_lru, &reaplist); } spin_unlock(&state_lock); @@ -6314,7 +6322,7 @@ static u64 nfsd_find_all_delegations(struct nfs4_client *clp, u64 max, continue; atomic_inc(&clp->cl_refcount); - unhash_delegation_locked(dp); + WARN_ON(!unhash_delegation_locked(dp)); list_add(&dp->dl_recall_lru, victims); } ++count; @@ -6645,7 +6653,7 @@ nfs4_state_shutdown_net(struct net *net) spin_lock(&state_lock); list_for_each_safe(pos, next, &nn->del_recall_lru) { dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru); - unhash_delegation_locked(dp); + WARN_ON(!unhash_delegation_locked(dp)); list_add(&dp->dl_recall_lru, &reaplist); } spin_unlock(&state_lock); |