Re: [PATCH v2] nfsd: fix bug on nfs4 stateid deallocation
From: J. Bruce Fields
Date: Wed Apr 03 2013 - 14:55:17 EST
On Wed, Apr 03, 2013 at 06:58:43PM +0800, Yanchuan Nian wrote:
> On Mon, Apr 01, 2013 at 09:50:44PM -0400, J. Bruce Fields wrote:
> > On Wed, Mar 13, 2013 at 11:04:54PM +0800, Yanchuan Nian wrote:
> > > 2013/3/11 J. Bruce Fields <bfields@xxxxxxxxxxxx>
> > >
> > > > On Mon, Mar 11, 2013 at 08:46:14AM +0800, ycnian@xxxxxxxxx wrote:
> > > > > NFS4_OO_PURGE_CLOSE is not handled properly. To avoid memory leak, nfs4
> > > > > stateid which is pointed by oo_last_closed_stid is freed in
> > > > nfsd4_close(),
> > > > > but NFS4_OO_PURGE_CLOSE isn't cleared meanwhile. So the stateid released
> > > > in
> > > > > THIS close procedure may be freed immediately in the coming encoding
> > > > function.
> > > >
> > > > OK, makes sense. This code is confusing, I wonder if there's some way
> > > > we could make it simpler.
> > > >
> > >
> > > The only purpose of NFS4_OO_PURGE_CLOSE is to decide whether the stateid
> > > pointed by last-closed-stateid should be freed or not. I wonder if this
> > > flag is necessary. oo_last_closed_stid is set only in CLOSE, so in other
> > > procedures, if the pointer is not NULL, it must be set in previous
> > > procedure, we can free it directly. In CLOSE procedure, we also free it
> > > directly before asigning the new released stateid to it in nfsd4_close(),
> > > and then we can ignore it in nfsd4_encode_close(). What do you think?
> >
> > Yeah, something like that would be simpler, I think. Maybe the
> > following? (On top of your patch.)
>
> This patch may cause memory leak in NFSv4.1. If the stateid released
> is the last one in nfs4_openowner, nfs4_openowner will be deallocated
> immediately, and NULL will be assigned to cstate->replay_owner at the
> same time. In this situation encode_seqid_op_tail() cannot be called.
> To avoid this problem, we can free the stateid just before or after
> nfs4_opwnowner deallocation.
Yes, thanks for catching that!:
nfsd4_close_open_stateid(stp);
- close->cl_closed_stateid = stp;
+ if (cstate->minorversion) {
+ unhash_stid(&stp->st_stid);
+ free_generic_stateid(stp);
+ } else
+ close->cl_closed_stateid = stp;
if (list_empty(&oo->oo_owner.so_stateids)) {
if (cstate->minorversion) {
> Another question, cl_stateid in struct nfsd4_close will be returned to
> the client, so original comment is right even though applying this
> patch. Can this struct be commented like this.
>
> struct nfsd4_close {
> u32 cl_seqid; /* request */
> stateid_t cl_stateid; /* request+response */
> struct nfs4_ol_stateid *cl_closed_stateid; /* used during processing */
Agreed; done. The result is the following (untested).
--b.
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 3e1101a..9bd6653 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -674,7 +674,7 @@ static void unhash_openowner(struct nfs4_openowner *oo)
}
}
-static void release_last_closed_stateid(struct nfs4_openowner *oo)
+void release_last_closed_stateid(struct nfs4_openowner *oo)
{
struct nfs4_ol_stateid *s = oo->oo_last_closed_stid;
@@ -3783,26 +3783,6 @@ out:
return status;
}
-void nfsd4_purge_closed_stateid(struct nfs4_stateowner *so)
-{
- struct nfs4_openowner *oo;
- struct nfs4_ol_stateid *s;
-
- if (!so->so_is_open_owner)
- return;
- oo = openowner(so);
- s = oo->oo_last_closed_stid;
- if (!s)
- return;
- if (!(oo->oo_flags & NFS4_OO_PURGE_CLOSE)) {
- /* Release the last_closed_stid on the next seqid bump: */
- oo->oo_flags |= NFS4_OO_PURGE_CLOSE;
- return;
- }
- oo->oo_flags &= ~NFS4_OO_PURGE_CLOSE;
- release_last_closed_stateid(oo);
-}
-
static void nfsd4_close_open_stateid(struct nfs4_ol_stateid *s)
{
unhash_open_stateid(s);
@@ -3839,9 +3819,11 @@ nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
memcpy(&close->cl_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
nfsd4_close_open_stateid(stp);
- release_last_closed_stateid(oo);
- oo->oo_flags &= ~NFS4_OO_PURGE_CLOSE;
- oo->oo_last_closed_stid = stp;
+ if (cstate->minorversion) {
+ unhash_stid(&stp->st_stid);
+ free_generic_stateid(stp);
+ } else
+ close->cl_closed_stateid = stp;
if (list_empty(&oo->oo_owner.so_stateids)) {
if (cstate->minorversion) {
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 700de01..60e196f 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -527,6 +527,7 @@ nfsd4_decode_close(struct nfsd4_compoundargs *argp, struct nfsd4_close *close)
{
DECODE_HEAD;
+ close->cl_closed_stateid = NULL;
READ_BUF(4);
READ32(close->cl_seqid);
return nfsd4_decode_stateid(argp, &close->cl_stateid);
@@ -1707,8 +1708,7 @@ static void write_cinfo(__be32 **p, struct nfsd4_change_info *c)
* Note that we increment sequence id's here, at the last moment, so we're sure
* we know whether the error to be returned is a sequence id mutating error.
*/
-
-static void encode_seqid_op_tail(struct nfsd4_compoundres *resp, __be32 *save, __be32 nfserr)
+static void encode_seqid_op_tail(struct nfsd4_compoundres *resp, __be32 *save, __be32 nfserr, struct nfs4_ol_stateid *close_stp)
{
struct nfs4_stateowner *stateowner = resp->cstate.replay_owner;
@@ -1719,7 +1719,13 @@ static void encode_seqid_op_tail(struct nfsd4_compoundres *resp, __be32 *save, _
(char *)resp->p - (char *)save;
memcpy(stateowner->so_replay.rp_buf, save,
stateowner->so_replay.rp_buflen);
- nfsd4_purge_closed_stateid(stateowner);
+ if (stateowner->so_is_open_owner) {
+ struct nfs4_openowner *oo = openowner(stateowner);
+
+ release_last_closed_stateid(oo);
+ if (close_stp)
+ oo->oo_last_closed_stid = close_stp;
+ }
}
}
@@ -2667,7 +2673,7 @@ nfsd4_encode_close(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_c
if (!nfserr)
nfsd4_encode_stateid(resp, &close->cl_stateid);
- encode_seqid_op_tail(resp, save, nfserr);
+ encode_seqid_op_tail(resp, save, nfserr, close->cl_closed_stateid);
return nfserr;
}
@@ -2770,7 +2776,7 @@ nfsd4_encode_lock(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_lo
else if (nfserr == nfserr_denied)
nfsd4_encode_lock_denied(resp, &lock->lk_denied);
- encode_seqid_op_tail(resp, save, nfserr);
+ encode_seqid_op_tail(resp, save, nfserr, NULL);
return nfserr;
}
@@ -2790,7 +2796,7 @@ nfsd4_encode_locku(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_l
if (!nfserr)
nfsd4_encode_stateid(resp, &locku->lu_stateid);
- encode_seqid_op_tail(resp, save, nfserr);
+ encode_seqid_op_tail(resp, save, nfserr, NULL);
return nfserr;
}
@@ -2885,7 +2891,7 @@ nfsd4_encode_open(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_op
}
/* XXX save filehandle here */
out:
- encode_seqid_op_tail(resp, save, nfserr);
+ encode_seqid_op_tail(resp, save, nfserr, NULL);
return nfserr;
}
@@ -2897,7 +2903,7 @@ nfsd4_encode_open_confirm(struct nfsd4_compoundres *resp, __be32 nfserr, struct
if (!nfserr)
nfsd4_encode_stateid(resp, &oc->oc_resp_stateid);
- encode_seqid_op_tail(resp, save, nfserr);
+ encode_seqid_op_tail(resp, save, nfserr, NULL);
return nfserr;
}
@@ -2909,7 +2915,7 @@ nfsd4_encode_open_downgrade(struct nfsd4_compoundres *resp, __be32 nfserr, struc
if (!nfserr)
nfsd4_encode_stateid(resp, &od->od_stateid);
- encode_seqid_op_tail(resp, save, nfserr);
+ encode_seqid_op_tail(resp, save, nfserr, NULL);
return nfserr;
}
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index f6ae4db..477f027 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -355,7 +355,6 @@ struct nfs4_openowner {
struct nfs4_ol_stateid *oo_last_closed_stid;
time_t oo_time; /* time of placement on so_close_lru */
#define NFS4_OO_CONFIRMED 1
-#define NFS4_OO_PURGE_CLOSE 2
#define NFS4_OO_NEW 4
unsigned char oo_flags;
};
@@ -363,7 +362,7 @@ struct nfs4_openowner {
struct nfs4_lockowner {
struct nfs4_stateowner lo_owner; /* must be first element */
struct list_head lo_owner_ino_hash; /* hash by owner,file */
- struct list_head lo_perstateid; /* for lockowners only */
+ struct list_head lo_perstateid;
struct list_head lo_list; /* for temporary uses */
};
@@ -477,7 +476,7 @@ extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(const char *name,
struct nfsd_net *nn);
extern bool nfs4_has_reclaimed_state(const char *name, struct nfsd_net *nn);
extern void put_client_renew(struct nfs4_client *clp);
-extern void nfsd4_purge_closed_stateid(struct nfs4_stateowner *);
+extern void release_last_closed_stateid(struct nfs4_openowner *);
/* nfs4recover operations */
extern int nfsd4_client_tracking_init(struct net *net);
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 40e05e6..4d501db 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -91,7 +91,8 @@ struct nfsd4_access {
struct nfsd4_close {
u32 cl_seqid; /* request */
- stateid_t cl_stateid; /* request+response */
+ stateid_t cl_stateid; /* request */
+ struct nfs4_ol_stateid *cl_closed_stateid; /* used during processing */
};
struct nfsd4_commit {
--
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