NFS: Allow walking nfs_client.cl_superblocks list outside client.c
We're about to move some fields from struct nfs_client to struct
nfs_server. There is a many-to-one relationship between nfs_servers
and nfs_clients. After these fields are moved to the nfs_server
struct, to visit all of the data in these fields that is owned by one
nfs_client, code will need to visit each nfs_server on the
cl_superblocks list for that nfs_client.
To serialize changes to the cl_superblocks list during these little
expeditions, protect the list with RCU.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 684b677..32b5fbf 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1003,6 +1003,27 @@
target->options = source->options;
}
+static void nfs_server_insert_lists(struct nfs_server *server)
+{
+ struct nfs_client *clp = server->nfs_client;
+
+ spin_lock(&nfs_client_lock);
+ list_add_tail_rcu(&server->client_link, &clp->cl_superblocks);
+ list_add_tail(&server->master_link, &nfs_volume_list);
+ spin_unlock(&nfs_client_lock);
+
+}
+
+static void nfs_server_remove_lists(struct nfs_server *server)
+{
+ spin_lock(&nfs_client_lock);
+ list_del_rcu(&server->client_link);
+ list_del(&server->master_link);
+ spin_unlock(&nfs_client_lock);
+
+ synchronize_rcu();
+}
+
/*
* Allocate and initialise a server record
*/
@@ -1046,11 +1067,8 @@
{
dprintk("--> nfs_free_server()\n");
+ nfs_server_remove_lists(server);
unset_pnfs_layoutdriver(server);
- spin_lock(&nfs_client_lock);
- list_del(&server->client_link);
- list_del(&server->master_link);
- spin_unlock(&nfs_client_lock);
if (server->destroy != NULL)
server->destroy(server);
@@ -1125,11 +1143,7 @@
(unsigned long long) server->fsid.major,
(unsigned long long) server->fsid.minor);
- spin_lock(&nfs_client_lock);
- list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
- list_add_tail(&server->master_link, &nfs_volume_list);
- spin_unlock(&nfs_client_lock);
-
+ nfs_server_insert_lists(server);
server->mount_time = jiffies;
nfs_free_fattr(fattr);
return server;
@@ -1454,11 +1468,7 @@
if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
server->namelen = NFS4_MAXNAMLEN;
- spin_lock(&nfs_client_lock);
- list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
- list_add_tail(&server->master_link, &nfs_volume_list);
- spin_unlock(&nfs_client_lock);
-
+ nfs_server_insert_lists(server);
server->mount_time = jiffies;
out:
nfs_free_fattr(fattr);
@@ -1663,11 +1673,7 @@
if (error < 0)
goto out_free_server;
- spin_lock(&nfs_client_lock);
- list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
- list_add_tail(&server->master_link, &nfs_volume_list);
- spin_unlock(&nfs_client_lock);
-
+ nfs_server_insert_lists(server);
server->mount_time = jiffies;
nfs_free_fattr(fattr_fsinfo);