[PATCH v2 2/4] nfsd: Support the server resetting the boot verifier

Trond Myklebust
2019-09-02T17:06:29Z

Add support to allow the server to reset the boot verifier in order to
force clients to resend I/O after a timeout failure.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
---
fs/nfsd/netns.h | 4 ++++
fs/nfsd/nfs3xdr.c | 13 +++++++++----
fs/nfsd/nfs4proc.c | 14 ++++----------
fs/nfsd/nfsctl.c | 1 +
fs/nfsd/nfssvc.c | 31 ++++++++++++++++++++++++++++++-
5 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index bdfe5bcb3dcd..9a4ef815fb8c 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -104,6 +104,7 @@ struct nfsd_net {

/* Time of server startup */
struct timespec64 nfssvc_boot;
+ seqlock_t boot_lock;

/*
* Max number of connections this nfsd container will allow. Defaults
@@ -179,4 +180,7 @@ struct nfsd_net {
extern void nfsd_netns_free_versions(struct nfsd_net *nn);

extern unsigned int nfsd_net_id;
+
+void nfsd_copy_boot_verifier(__be32 verf[2], struct nfsd_net *nn);
+void nfsd_reset_boot_verifier(struct nfsd_net *nn);
#endif /* __NFSD_NETNS_H__ */
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index fcf31822c74c..86e5658651f1 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -27,6 +27,7 @@ static u32 nfs3_ftypes[] = {
NF3SOCK, NF3BAD, NF3LNK, NF3BAD,
};

+
/*
* XDR functions for basic NFS types
*/
@@ -751,14 +752,16 @@ nfs3svc_encode_writeres(struct svc_rqst *rqstp, __be32 *p)
{
struct nfsd3_writeres *resp = rqstp->rq_resp;
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+ __be32 verf[2];

p = encode_wcc_data(rqstp, p, &resp->fh);
if (resp->status == 0) {
*p++ = htonl(resp->count);
*p++ = htonl(resp->committed);
/* unique identifier, y2038 overflow can be ignored */
- *p++ = htonl((u32)nn->nfssvc_boot.tv_sec);
- *p++ = htonl(nn->nfssvc_boot.tv_nsec);
+ nfsd_copy_boot_verifier(verf, nn);
+ *p++ = verf[0];
+ *p++ = verf[1];
}
return xdr_ressize_check(rqstp, p);
}
@@ -1125,13 +1128,15 @@ nfs3svc_encode_commitres(struct svc_rqst *rqstp, __be32 *p)
{
struct nfsd3_commitres *resp = rqstp->rq_resp;
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+ __be32 verf[2];

p = encode_wcc_data(rqstp, p, &resp->fh);
/* Write verifier */
if (resp->status == 0) {
/* unique identifier, y2038 overflow can be ignored */
- *p++ = htonl((u32)nn->nfssvc_boot.tv_sec);
- *p++ = htonl(nn->nfssvc_boot.tv_nsec);
+ nfsd_copy_boot_verifier(verf, nn);
+ *p++ = verf[0];
+ *p++ = verf[1];
}
return xdr_ressize_check(rqstp, p);
}
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index cb51893ec1cd..4e3e77b76411 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -568,17 +568,11 @@ nfsd4_access(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,

static void gen_boot_verifier(nfs4_verifier *verifier, struct net *net)
{
- __be32 verf[2];
- struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+ __be32 *verf = (__be32 *)verifier->data;

- /*
- * This is opaque to client, so no need to byte-swap. Use
- * __force to keep sparse happy. y2038 time_t overflow is
- * irrelevant in this usage.
- */
- verf[0] = (__force __be32)nn->nfssvc_boot.tv_sec;
- verf[1] = (__force __be32)nn->nfssvc_boot.tv_nsec;
- memcpy(verifier->data, verf, sizeof(verifier->data));
+ BUILD_BUG_ON(2*sizeof(*verf) != sizeof(verifier->data));
+
+ nfsd_copy_boot_verifier(verf, net_generic(net, nfsd_net_id));
}

static __be32
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 3cf4f6aa48d6..33cbe2e5d937 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1477,6 +1477,7 @@ static __net_init int nfsd_init_net(struct net *net)

atomic_set(&nn->ntf_refcnt, 0);
init_waitqueue_head(&nn->ntf_wq);
+ seqlock_init(&nn->boot_lock);

mnt = vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL);
if (IS_ERR(mnt)) {
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index b944553c6927..3caaf5675259 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -344,6 +344,35 @@ static bool nfsd_needs_lockd(struct nfsd_net *nn)
return nfsd_vers(nn, 2, NFSD_TEST) || nfsd_vers(nn, 3, NFSD_TEST);
}

+void nfsd_copy_boot_verifier(__be32 verf[2], struct nfsd_net *nn)
+{
+ int seq = 0;
+
+ do {
+ read_seqbegin_or_lock(&nn->boot_lock, &seq);
+ /*
+ * This is opaque to client, so no need to byte-swap. Use
+ * __force to keep sparse happy. y2038 time_t overflow is
+ * irrelevant in this usage
+ */
+ verf[0] = (__force __be32)nn->nfssvc_boot.tv_sec;
+ verf[1] = (__force __be32)nn->nfssvc_boot.tv_nsec;
+ } while (need_seqretry(&nn->boot_lock, seq));
+ done_seqretry(&nn->boot_lock, seq);
+}
+
+void nfsd_reset_boot_verifier_locked(struct nfsd_net *nn)
+{
+ ktime_get_real_ts64(&nn->nfssvc_boot);
+}
+
+void nfsd_reset_boot_verifier(struct nfsd_net *nn)
+{
+ write_seqlock(&nn->boot_lock);
+ nfsd_reset_boot_verifier_locked(nn);
+ write_sequnlock(&nn->boot_lock);
+}
+
static int nfsd_startup_net(int nrservs, struct net *net, const struct cred *cred)
{
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
@@ -596,7 +625,7 @@ int nfsd_create_serv(struct net *net)
#endif
}
atomic_inc(&nn->ntf_refcnt);
- ktime_get_real_ts64(&nn->nfssvc_boot); /* record boot time */
+ nfsd_reset_boot_verifier(nn);
return 0;
}

--
2.21.0