[PATCH Version 4 07/10] NFS probe pseudo-fs for replicas

[<andros@netapp.com>]

From: Andy Adamson <andros@netapp.com>

Probe an NFSv4 Pseudo-fs for fs_locations replicas. Replicas on a Pseudo-fs
returns multipath addresses for the server which will be tested
for session trunking.

Signed-off-by: Andy Adamson <andros@netapp.com>
---
 fs/nfs/internal.h       |  2 ++
 fs/nfs/nfs4getroot.c    |  3 ++
 fs/nfs/nfs4proc.c       | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
 fs/nfs/nfs4xdr.c        | 14 ++++++++-
 include/linux/nfs_xdr.h |  4 +--
 5 files changed, 104 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index f1d1d2c..4a65288 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -528,6 +528,8 @@ extern int nfs40_walk_client_list(struct nfs_client *clp,
 extern int nfs41_walk_client_list(struct nfs_client *clp,
 				struct nfs_client **result,
 				struct rpc_cred *cred);
+extern void nfs4_get_pseudofs_replicas(struct nfs_server *server,
+				struct nfs_fh *mntfh);
 
 static inline struct inode *nfs_igrab_and_active(struct inode *inode)
 {
diff --git a/fs/nfs/nfs4getroot.c b/fs/nfs/nfs4getroot.c
index 039b3eb..4c1f5e4 100644
--- a/fs/nfs/nfs4getroot.c
+++ b/fs/nfs/nfs4getroot.c
@@ -36,6 +36,9 @@ int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool auth_p
 	}
 
 	memcpy(&server->fsid, &fsinfo.fattr->fsid, sizeof(server->fsid));
+
+	nfs4_get_pseudofs_replicas(server, mntfh);
+
 out:
 	nfs_free_fattr(fsinfo.fattr);
 	dprintk("<-- nfs4_get_rootfh() = %d\n", ret);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 70537f0..8263ee8 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3253,6 +3253,90 @@ static int nfs4_do_find_root_sec(struct nfs_server *server,
 	return nfs_v4_minor_ops[mv]->find_root_sec(server, fhandle, info);
 }
 
+static int _nfs4_proc_fs_locations_probe(struct nfs_server *server,
+					 struct nfs_fh *fhandle,
+					 struct nfs4_fs_locations *fs_locations,
+					 struct page *page)
+{
+	u32 bitmask[3] = {
+		[0] = FATTR4_WORD0_FS_LOCATIONS,
+	};
+	struct nfs4_fs_locations_arg args = {
+		.fh = fhandle,
+		.page = page,
+		.bitmask = bitmask,
+		.replicas = 1,
+	};
+	struct nfs4_fs_locations_res res = {
+		.fs_locations = fs_locations,
+		.replicas = 1,
+	};
+	struct rpc_message msg = {
+		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_FS_LOCATIONS],
+		.rpc_argp = &args,
+		.rpc_resp = &res,
+	};
+	struct rpc_clnt *clnt = server->nfs_client->cl_rpcclient;
+	int status = 0;
+
+	nfs_fattr_init(&fs_locations->fattr);
+	fs_locations->nlocations = 0;
+	fs_locations->server = server;
+	status = nfs4_call_sync(clnt, server, &msg, &args.seq_args,
+				&res.seq_res, 0);
+	return status;
+}
+
+static int nfs4_proc_fs_locations_probe(struct nfs_server *server,
+					struct nfs_fh *fhandle,
+					struct nfs4_fs_locations *fs_locations,
+					struct page *page)
+{
+	struct nfs4_exception exception = { };
+	int err;
+
+	do {
+		err = _nfs4_proc_fs_locations_probe(server, fhandle,
+						fs_locations, page);
+		err = nfs4_handle_exception(server, err, &exception);
+	} while (exception.retry);
+	return err;
+}
+
+
+/**
+ * Probe the pseudo filesystem for an fs_locations replicas list.
+ * Note: The replicas list on a pseudofs is a list of multipath
+ * addresses
+ */
+void nfs4_get_pseudofs_replicas(struct nfs_server *server,
+				       struct nfs_fh *mntfh)
+{
+	struct page *page = NULL;
+	struct nfs4_fs_locations *locations = NULL;
+	int status;
+
+	if (server->nfs_client->cl_minorversion == 0)
+		return;
+
+	page = alloc_page(GFP_KERNEL);
+	if (page == NULL)
+		goto out;
+	locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
+	if (locations == NULL)
+		goto out;
+
+	status = nfs4_proc_fs_locations_probe(server, mntfh, locations, page);
+	if (status != 0)
+		goto out;
+
+	/* test replicas for session trunking here */
+out:
+	if (page)
+		__free_page(page);
+	kfree(locations);
+}
+
 /**
  * nfs4_proc_get_rootfh - get file handle for server's pseudoroot
  * @server: initialized nfs_server handle
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 88474a4..4dfd136 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -2685,7 +2685,11 @@ static void nfs4_xdr_enc_fs_locations(struct rpc_rqst *req,
 
 	encode_compound_hdr(xdr, req, &hdr);
 	encode_sequence(xdr, &args->seq_args, &hdr);
-	if (args->migration) {
+	if (args->replicas) {
+		encode_putfh(xdr, args->fh, &hdr);
+		replen = hdr.replen;
+		encode_fs_locations(xdr, args->bitmask, &hdr);
+	} else if (args->migration) {
 		encode_putfh(xdr, args->fh, &hdr);
 		replen = hdr.replen;
 		encode_fs_locations(xdr, args->bitmask, &hdr);
@@ -6916,6 +6920,14 @@ static int nfs4_xdr_dec_fs_locations(struct rpc_rqst *req,
 	status = decode_putfh(xdr);
 	if (status)
 		goto out;
+	if (res->replicas) {
+		xdr_enter_page(xdr, PAGE_SIZE);
+		status = decode_getfattr_generic(xdr,
+					&res->fs_locations->fattr,
+					 NULL, res->fs_locations,
+					 NULL, res->fs_locations->server);
+		goto out;
+	}
 	if (res->migration) {
 		xdr_enter_page(xdr, PAGE_SIZE);
 		status = decode_getfattr_generic(xdr,
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index d320906..ab9a08a2 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1120,13 +1120,13 @@ struct nfs4_fs_locations_arg {
 	struct page *page;
 	const u32 *bitmask;
 	clientid4 clientid;
-	unsigned char migration:1, renew:1;
+	unsigned char migration:1, renew:1, replicas:1;
 };
 
 struct nfs4_fs_locations_res {
 	struct nfs4_sequence_res	seq_res;
 	struct nfs4_fs_locations       *fs_locations;
-	unsigned char			migration:1, renew:1;
+	unsigned char			migration:1, renew:1, replicas:1;
 };
 
 struct nfs4_secinfo4 {
-- 
1.8.3.1