NFS: replace global bl_mount_reply with per-net one

This global variable is used for blocklayout downcall and thus can be corrupted
if case of existence of multiple networks namespaces.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/blocklayout/blocklayout.h

@@ -153,11 +153,6 @@ BLK_LSEG2EXT(struct pnfs_layout_segment *lseg)
 	return BLK_LO2EXT(lseg->pls_layout);
 }
 
-struct bl_dev_msg {
-	int32_t status;
-	uint32_t major, minor;
-};
-
 struct bl_msg_hdr {
 	u8  type;
 	u16 totallen; /* length of entire message, including hdr itself */

fs/nfs/blocklayout/blocklayoutdev.c

@@ -79,15 +79,16 @@ int nfs4_blkdev_put(struct block_device *bdev)
 	return blkdev_put(bdev, FMODE_READ);
 }
 
-static struct bl_dev_msg bl_mount_reply;
-
 ssize_t bl_pipe_downcall(struct file *filp, const char __user *src,
 			 size_t mlen)
 {
+	struct nfs_net *nn = net_generic(filp->f_dentry->d_sb->s_fs_info,
+					 nfs_net_id);
+
 	if (mlen != sizeof (struct bl_dev_msg))
 		return -EINVAL;
 
-	if (copy_from_user(&bl_mount_reply, src, mlen) != 0)
+	if (copy_from_user(&nn->bl_mount_reply, src, mlen) != 0)
 		return -EFAULT;
 
 	wake_up(&bl_wq);
@@ -118,10 +119,10 @@ nfs4_blk_decode_device(struct nfs_server *server,
 	};
 	uint8_t *dataptr;
 	DECLARE_WAITQUEUE(wq, current);
-	struct bl_dev_msg *reply = &bl_mount_reply;
 	int offset, len, i, rc;
 	struct net *net = server->nfs_client->net;
 	struct nfs_net *nn = net_generic(net, nfs_net_id);
+	struct bl_dev_msg *reply = &nn->bl_mount_reply;
 
 	dprintk("%s CREATING PIPEFS MESSAGE\n", __func__);
 	dprintk("%s: deviceid: %s, mincount: %d\n", __func__, dev->dev_id.data,

fs/nfs/netns.h

@@ -4,9 +4,15 @@
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
+struct bl_dev_msg {
+	int32_t status;
+	uint32_t major, minor;
+};
+
 struct nfs_net {
 	struct cache_detail *nfs_dns_resolve;
 	struct rpc_pipe *bl_device_pipe;
+	struct bl_dev_msg bl_mount_reply;
 	struct list_head nfs_client_list;
 	struct list_head nfs_volume_list;
 #ifdef CONFIG_NFS_V4