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| author | J. Bruce Fields <bfields@citi.umich.edu> | 2010-04-24 15:35:43 -0400 |
|---|---|---|
| committer | J. Bruce Fields <bfields@citi.umich.edu> | 2010-05-03 08:32:31 -0400 |
| commit | 26c0c75e69265961e891ed80b38fb62a548ab371 (patch) | |
| tree | 1ecbc767a1b2ad3e8f25d88e918076806d8c2eb1 | |
| parent | e0c8233622cbd49d171bc57b60e725f2fb748750 (diff) | |
| download | lwn-26c0c75e69265961e891ed80b38fb62a548ab371.tar.gz lwn-26c0c75e69265961e891ed80b38fb62a548ab371.zip | |
nfsd4: fix unlikely race in session replay case
In the replay case, the
renew_client(session->se_client);
happens after we've droppped the sessionid_lock, and without holding a
reference on the session; so there's nothing preventing the session
being freed before we get here.
Thanks to Benny Halevy for catching a bug in an earlier version of this
patch.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Acked-by: Benny Halevy <bhalevy@panasas.com>
| -rw-r--r-- | fs/nfsd/nfs4proc.c | 1 | ||||
| -rw-r--r-- | fs/nfsd/nfs4state.c | 7 | ||||
| -rw-r--r-- | fs/nfsd/nfs4xdr.c | 10 |
3 files changed, 10 insertions, 8 deletions
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index e147dbcb7ef7..61282f8405b5 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1027,6 +1027,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp, resp->rqstp = rqstp; resp->cstate.minorversion = args->minorversion; resp->cstate.replay_owner = NULL; + resp->cstate.session = NULL; fh_init(&resp->cstate.current_fh, NFS4_FHSIZE); fh_init(&resp->cstate.save_fh, NFS4_FHSIZE); /* Use the deferral mechanism only for NFSv4.0 compounds */ diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index bba9fff49cfe..737315c61e7e 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1443,11 +1443,10 @@ nfsd4_sequence(struct svc_rqst *rqstp, cstate->slot = slot; cstate->session = session; - /* Hold a session reference until done processing the compound: - * nfsd4_put_session called only if the cstate slot is set. - */ - nfsd4_get_session(session); out: + /* Hold a session reference until done processing the compound. */ + if (cstate->session) + nfsd4_get_session(cstate->session); spin_unlock(&sessionid_lock); /* Renew the clientid on success and on replay */ if (cstate->session) { diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index fb27b1db007b..05bc5bd63c95 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -3306,10 +3306,12 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo iov = &rqstp->rq_res.head[0]; iov->iov_len = ((char*)resp->p) - (char*)iov->iov_base; BUG_ON(iov->iov_len > PAGE_SIZE); - if (nfsd4_has_session(cs) && cs->status != nfserr_replay_cache) { - nfsd4_store_cache_entry(resp); - dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__); - resp->cstate.slot->sl_inuse = false; + if (nfsd4_has_session(cs)) { + if (cs->status != nfserr_replay_cache) { + nfsd4_store_cache_entry(resp); + dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__); + resp->cstate.slot->sl_inuse = false; + } nfsd4_put_session(resp->cstate.session); } return 1; |