[PATCH/RFC v3 02/10] Save root file handle in nfs_server.

[Matthew Treinish <treinish@linux.vnet.ibm.com>]

Save each FSID's root directory file handle in the
export's local nfs_server structure on the client.
This FH can then be used as the end case for the recursive
walkback during VFH recovery.

This was originally written by Chuck Lever so that
the FH can be used for migration recovery logic.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Matthew Treinish <treinish@linux.vnet.ibm.com>
---
 fs/nfs/client.c           |    1 +
 fs/nfs/getroot.c          |    7 +++++++
 include/linux/nfs_fs_sb.h |    1 +
 3 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 2f96f9d..7566325 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1137,6 +1137,7 @@ void nfs_free_server(struct nfs_server *server)
 	ida_destroy(&server->lockowner_id);
 	ida_destroy(&server->openowner_id);
 	nfs_free_iostats(server->io_stats);
+	nfs_free_fhandle(server->rootfh);
 	bdi_destroy(&server->backing_dev_info);
 	kfree(server);
 	nfs_release_automount_timer();
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index dcb6154..51ca63b 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -232,6 +232,13 @@ struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh,
 		ret = ERR_CAST(inode);
 		goto out;
 	}
+	server->rootfh = nfs_alloc_fhandle();
+	if (server->rootfh == NULL) {
+		dprintk("nfs_get_root: alloc rootfh failed\n");
+		ret = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+	nfs_copy_fh(server->rootfh, mntfh);
 
 	error = nfs_superblock_set_dummy_root(sb, inode);
 	if (error != 0) {
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 15a2056..5993319 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -160,6 +160,7 @@ struct nfs_server {
 	struct list_head	layouts;
 	struct list_head	delegations;
 	void (*destroy)(struct nfs_server *);
+	struct nfs_fh		*rootfh;
 
 	atomic_t active; /* Keep trace of any activity to this server */
 
-- 
1.7.4.4