NFS: Add method to detect whether an FSID is still on the server

Introduce a mechanism for probing a server to determine if an FSID
is present or absent.

The on-the-wire compound is different between minor version 0 and 1.
Minor version 0 appends a RENEW operation to identify which client
ID is probing.  Minor version 1 has a SEQUENCE operation in the
compound which effectively carries the same information.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 195 insertions, 2 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 94e783f..2f0f8c2 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -208,6 +208,7 @@ struct nfs4_state_maintenance_ops {
 struct nfs4_mig_recovery_ops {
 	int (*get_locations)(struct inode *, struct nfs4_fs_locations *,
 		struct page *, struct rpc_cred *);
+	int (*fsid_present)(struct inode *, struct rpc_cred *);
 };
 
 extern const struct dentry_operations nfs4_dentry_operations;
@@ -242,6 +243,7 @@ extern int nfs4_proc_fs_locations(struct rpc_clnt *, struct inode *, const struc
 				  struct nfs4_fs_locations *, struct page *);
 extern int nfs4_proc_get_locations(struct inode *, struct nfs4_fs_locations *,
 		struct page *page, struct rpc_cred *);
+extern int nfs4_proc_fsid_present(struct inode *, struct rpc_cred *);
 extern struct rpc_clnt *nfs4_proc_lookup_mountpoint(struct inode *, struct qstr *,
 			    struct nfs_fh *, struct nfs_fattr *);
 extern int nfs4_proc_secinfo(struct inode *, const struct qstr *, struct nfs4_secinfo_flavors *);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 552e4f7..01b90bd 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6153,6 +6153,132 @@ int nfs4_proc_get_locations(struct inode *inode,
 	return status;
 }
 
+/*
+ * This operation also signals the server that this client is
+ * performing "lease moved" recovery.  The server can stop
+ * returning NFS4ERR_LEASE_MOVED to this client.  A RENEW operation
+ * is appended to this compound to identify the client ID which is
+ * performing recovery.
+ */
+static int _nfs40_proc_fsid_present(struct inode *inode, struct rpc_cred *cred)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
+	struct rpc_clnt *clnt = server->client;
+	struct nfs4_fsid_present_arg args = {
+		.fh		= NFS_FH(inode),
+		.clientid	= clp->cl_clientid,
+		.renew		= 1,		/* append RENEW */
+	};
+	struct nfs4_fsid_present_res res = {
+		.renew		= 1,
+	};
+	struct rpc_message msg = {
+		.rpc_proc	= &nfs4_procedures[NFSPROC4_CLNT_FSID_PRESENT],
+		.rpc_argp	= &args,
+		.rpc_resp	= &res,
+		.rpc_cred	= cred,
+	};
+	unsigned long now = jiffies;
+	int status;
+
+	res.fh = nfs_alloc_fhandle();
+	if (res.fh == NULL)
+		return -ENOMEM;
+
+	nfs4_init_sequence(&args.seq_args, &res.seq_res, 0);
+	nfs4_set_sequence_privileged(&args.seq_args);
+	status = nfs4_call_sync_sequence(clnt, server, &msg,
+						&args.seq_args, &res.seq_res);
+	nfs_free_fhandle(res.fh);
+	if (status)
+		return status;
+
+	do_renew_lease(clp, now);
+	return 0;
+}
+
+#ifdef CONFIG_NFS_V4_1
+
+/*
+ * This operation also signals the server that this client is
+ * performing "lease moved" recovery.  The server can stop asserting
+ * SEQ4_STATUS_LEASE_MOVED for this client.  The client ID performing
+ * this operation is identified in the SEQUENCE operation in this
+ * compound.
+ */
+static int _nfs41_proc_fsid_present(struct inode *inode, struct rpc_cred *cred)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	struct rpc_clnt *clnt = server->client;
+	struct nfs4_fsid_present_arg args = {
+		.fh		= NFS_FH(inode),
+	};
+	struct nfs4_fsid_present_res res = {
+	};
+	struct rpc_message msg = {
+		.rpc_proc	= &nfs4_procedures[NFSPROC4_CLNT_FSID_PRESENT],
+		.rpc_argp	= &args,
+		.rpc_resp	= &res,
+		.rpc_cred	= cred,
+	};
+	int status;
+
+	res.fh = nfs_alloc_fhandle();
+	if (res.fh == NULL)
+		return -ENOMEM;
+
+	nfs4_init_sequence(&args.seq_args, &res.seq_res, 0);
+	nfs4_set_sequence_privileged(&args.seq_args);
+	status = nfs4_call_sync_sequence(clnt, server, &msg,
+						&args.seq_args, &res.seq_res);
+	nfs_free_fhandle(res.fh);
+	if (status == NFS4_OK &&
+	    res.seq_res.sr_status_flags & SEQ4_STATUS_LEASE_MOVED)
+		status = -NFS4ERR_LEASE_MOVED;
+	return status;
+}
+
+#endif	/* CONFIG_NFS_V4_1 */
+
+/**
+ * nfs4_proc_fsid_present - Is this FSID present or absent on server?
+ * @inode: inode on FSID to check
+ * @cred: credential to use for this operation
+ *
+ * Server indicates whether the FSID is present, moved, or not
+ * recognized.  This operation is necessary to clear a LEASE_MOVED
+ * condition for this client ID.
+ *
+ * Returns NFS4_OK if the FSID is present on this server,
+ * -NFS4ERR_MOVED if the FSID is no longer present, a negative
+ *  NFS4ERR code if some error occurred on the server, or a
+ *  negative errno if a local failure occurred.
+ */
+int nfs4_proc_fsid_present(struct inode *inode, struct rpc_cred *cred)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	struct nfs_client *clp = server->nfs_client;
+	const struct nfs4_mig_recovery_ops *ops =
+					clp->cl_mvops->mig_recovery_ops;
+	struct nfs4_exception exception = { };
+	int status;
+
+	dprintk("%s: FSID %llx:%llx on \"%s\"\n", __func__,
+		(unsigned long long)server->fsid.major,
+		(unsigned long long)server->fsid.minor,
+		clp->cl_hostname);
+	nfs_display_fhandle(NFS_FH(inode), __func__);
+
+	do {
+		status = ops->fsid_present(inode, cred);
+		if (status != -NFS4ERR_DELAY)
+			break;
+		nfs4_handle_exception(server, status, &exception);
+	} while (exception.retry);
+	return status;
+}
+
 /**
  * If 'use_integrity' is true and the state managment nfs_client
  * cl_rpcclient is using krb5i/p, use the integrity protected cl_rpcclient
@@ -8052,11 +8178,13 @@ static const struct nfs4_state_maintenance_ops nfs41_state_renewal_ops = {
 
 static const struct nfs4_mig_recovery_ops nfs40_mig_recovery_ops = {
 	.get_locations = _nfs40_proc_get_locations,
+	.fsid_present = _nfs40_proc_fsid_present,
 };
 
 #if defined(CONFIG_NFS_V4_1)
 static const struct nfs4_mig_recovery_ops nfs41_mig_recovery_ops = {
 	.get_locations = _nfs41_proc_get_locations,
+	.fsid_present = _nfs41_proc_fsid_present,
 };
 #endif	/* CONFIG_NFS_V4_1 */
 
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 1854b04..f903389 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -595,11 +595,13 @@ static int nfs4_stat_to_errno(int);
 #define NFS4_enc_getattr_sz	(compound_encode_hdr_maxsz + \
 				encode_sequence_maxsz + \
 				encode_putfh_maxsz + \
-				encode_getattr_maxsz)
+				encode_getattr_maxsz + \
+				encode_renew_maxsz)
 #define NFS4_dec_getattr_sz	(compound_decode_hdr_maxsz + \
 				decode_sequence_maxsz + \
 				decode_putfh_maxsz + \
-				decode_getattr_maxsz)
+				decode_getattr_maxsz + \
+				decode_renew_maxsz)
 #define NFS4_enc_lookup_sz	(compound_encode_hdr_maxsz + \
 				encode_sequence_maxsz + \
 				encode_putfh_maxsz + \
@@ -753,6 +755,18 @@ static int nfs4_stat_to_errno(int);
 				decode_sequence_maxsz + \
 				decode_putfh_maxsz + \
 				decode_secinfo_maxsz)
+#define NFS4_enc_fsid_present_sz \
+				(compound_encode_hdr_maxsz + \
+				 encode_sequence_maxsz + \
+				 encode_putfh_maxsz + \
+				 encode_getfh_maxsz + \
+				 encode_renew_maxsz)
+#define NFS4_dec_fsid_present_sz \
+				(compound_decode_hdr_maxsz + \
+				 decode_sequence_maxsz + \
+				 decode_putfh_maxsz + \
+				 decode_getfh_maxsz + \
+				 decode_renew_maxsz)
 #if defined(CONFIG_NFS_V4_1)
 #define NFS4_enc_bind_conn_to_session_sz \
 				(compound_encode_hdr_maxsz + \
@@ -2726,6 +2740,26 @@ static void nfs4_xdr_enc_secinfo(struct rpc_rqst *req,
 	encode_nops(&hdr);
 }
 
+/*
+ * Encode FSID_PRESENT request
+ */
+static void nfs4_xdr_enc_fsid_present(struct rpc_rqst *req,
+				      struct xdr_stream *xdr,
+				      struct nfs4_fsid_present_arg *args)
+{
+	struct compound_hdr hdr = {
+		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
+	};
+
+	encode_compound_hdr(xdr, req, &hdr);
+	encode_sequence(xdr, &args->seq_args, &hdr);
+	encode_putfh(xdr, args->fh, &hdr);
+	encode_getfh(xdr, &hdr);
+	if (args->renew)
+		encode_renew(xdr, args->clientid, &hdr);
+	encode_nops(&hdr);
+}
+
 #if defined(CONFIG_NFS_V4_1)
 /*
  * BIND_CONN_TO_SESSION request
@@ -6883,6 +6917,34 @@ out:
 	return status;
 }
 
+/*
+ * Decode FSID_PRESENT response
+ */
+static int nfs4_xdr_dec_fsid_present(struct rpc_rqst *rqstp,
+				     struct xdr_stream *xdr,
+				     struct nfs4_fsid_present_res *res)
+{
+	struct compound_hdr hdr;
+	int status;
+
+	status = decode_compound_hdr(xdr, &hdr);
+	if (status)
+		goto out;
+	status = decode_sequence(xdr, &res->seq_res, rqstp);
+	if (status)
+		goto out;
+	status = decode_putfh(xdr);
+	if (status)
+		goto out;
+	status = decode_getfh(xdr, res->fh);
+	if (status)
+		goto out;
+	if (res->renew)
+		status = decode_renew(xdr);
+out:
+	return status;
+}
+
 #if defined(CONFIG_NFS_V4_1)
 /*
  * Decode BIND_CONN_TO_SESSION response
@@ -7397,6 +7459,7 @@ struct rpc_procinfo	nfs4_procedures[] = {
 	PROC(FS_LOCATIONS,	enc_fs_locations,	dec_fs_locations),
 	PROC(RELEASE_LOCKOWNER,	enc_release_lockowner,	dec_release_lockowner),
 	PROC(SECINFO,		enc_secinfo,		dec_secinfo),
+	PROC(FSID_PRESENT,	enc_fsid_present,	dec_fsid_present),
 #if defined(CONFIG_NFS_V4_1)
 	PROC(EXCHANGE_ID,	enc_exchange_id,	dec_exchange_id),
 	PROC(CREATE_SESSION,	enc_create_session,	dec_create_session),