[RFC PATCH 4/6] NFS: Implement NFSv4.2's OFFLOAD_STATUS operation

[cel@kernel.org]

From: Chuck Lever <chuck.lever@oracle.com>

Enable the Linux NFS client to observe the progress of an offloaded
asynchronous COPY operation. This new operation will be put to use
in a subsequent patch.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfs/nfs42proc.c        | 113 ++++++++++++++++++++++++++++++++++++++
 include/linux/nfs_fs_sb.h |   1 +
 2 files changed, 114 insertions(+)

diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
index 869605a0a9d5..c55247da8e49 100644
--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -21,6 +21,8 @@
 
 #define NFSDBG_FACILITY NFSDBG_PROC
 static int nfs42_do_offload_cancel_async(struct file *dst, nfs4_stateid *std);
+static int nfs42_proc_offload_status(struct file *file, nfs4_stateid *stateid,
+				     u64 *copied);
 
 static void nfs42_set_netaddr(struct file *filep, struct nfs42_netaddr *naddr)
 {
@@ -582,6 +584,117 @@ static int nfs42_do_offload_cancel_async(struct file *dst,
 	return status;
 }
 
+static void nfs42_offload_status_done(struct rpc_task *task, void *calldata)
+{
+	struct nfs42_offload_data *data = calldata;
+
+	if (!nfs4_sequence_done(task, &data->res.osr_seq_res))
+		return;
+
+	switch (task->tk_status) {
+	case 0:
+		return;
+	case -NFS4ERR_DELAY:
+	case -NFS4ERR_GRACE:
+		if (nfs4_async_handle_error(task, data->seq_server,
+					    NULL, NULL) == -EAGAIN)
+			rpc_restart_call_prepare(task);
+		else
+			task->tk_status = -EIO;
+		break;
+	case -NFS4ERR_ADMIN_REVOKED:
+	case -NFS4ERR_BAD_STATEID:
+	case -NFS4ERR_OLD_STATEID:
+		task->tk_status = -EBADF;
+		break;
+	case -NFS4ERR_NOTSUPP:
+	case -ENOTSUPP:
+	case -EOPNOTSUPP:
+		data->seq_server->caps &= ~NFS_CAP_OFFLOAD_STATUS;
+		task->tk_status = -EOPNOTSUPP;
+		break;
+	default:
+		task->tk_status = -EIO;
+	}
+}
+
+static const struct rpc_call_ops nfs42_offload_status_ops = {
+	.rpc_call_prepare = nfs42_offload_prepare,
+	.rpc_call_done = nfs42_offload_status_done,
+	.rpc_release = nfs42_offload_release
+};
+
+/*
+ * Return values:
+ *   %0: Server returned an NFS4_OK completion status
+ *   %-EINPROGRESS: Server returned no completion status
+ *   %-EREMOTEIO: Server returned an error completion status
+ *   %-EBADF: Server did not recognize the copy stateid
+ *   %-EOPNOTSUPP: Server does not support OFFLOAD_STATUS
+ *
+ * Other negative errnos indicate the client could not complete the
+ * request.
+ */
+static int nfs42_proc_offload_status(struct file *file, nfs4_stateid *stateid,
+				     u64 *copied)
+{
+	struct nfs_open_context *ctx = nfs_file_open_context(file);
+	struct nfs_server *server = NFS_SERVER(file_inode(file));
+	struct nfs42_offload_data *data = NULL;
+	struct rpc_message msg = {
+		.rpc_proc	= &nfs4_procedures[NFSPROC4_CLNT_OFFLOAD_STATUS],
+		.rpc_cred	= ctx->cred,
+	};
+	struct rpc_task_setup task_setup_data = {
+		.rpc_client	= server->client,
+		.rpc_message	= &msg,
+		.callback_ops	= &nfs42_offload_status_ops,
+		.workqueue	= nfsiod_workqueue,
+		.flags		= RPC_TASK_ASYNC | RPC_TASK_SOFTCONN,
+	};
+	struct rpc_task *task;
+	int status;
+
+	if (!(server->caps & NFS_CAP_OFFLOAD_STATUS))
+		return -EOPNOTSUPP;
+
+	data = kzalloc(sizeof(struct nfs42_offload_data), GFP_KERNEL);
+	if (data == NULL)
+		return -ENOMEM;
+
+	data->seq_server = server;
+	data->args.osa_src_fh = NFS_FH(file_inode(file));
+	memcpy(&data->args.osa_stateid, stateid,
+		sizeof(data->args.osa_stateid));
+	msg.rpc_argp = &data->args;
+	msg.rpc_resp = &data->res;
+	task_setup_data.callback_data = data;
+	nfs4_init_sequence(&data->args.osa_seq_args, &data->res.osr_seq_res,
+			   1, 0);
+	task = rpc_run_task(&task_setup_data);
+	if (IS_ERR(task)) {
+		nfs42_offload_release(data);
+		return PTR_ERR(task);
+	}
+	status = rpc_wait_for_completion_task(task);
+	if (status)
+		goto out;
+
+	*copied = data->res.osr_count;
+	if (!data->res.complete_count) {
+		status = -EINPROGRESS;
+		goto out;
+	}
+	if (data->res.osr_complete[0] != NFS_OK) {
+		status = -EREMOTEIO;
+		goto out;
+	}
+
+out:
+	rpc_put_task(task);
+	return status;
+}
+
 static int _nfs42_proc_copy_notify(struct file *src, struct file *dst,
 				   struct nfs42_copy_notify_args *args,
 				   struct nfs42_copy_notify_res *res)
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 92de074e63b9..0937e73c4767 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -278,6 +278,7 @@ struct nfs_server {
 #define NFS_CAP_LGOPEN		(1U << 5)
 #define NFS_CAP_CASE_INSENSITIVE	(1U << 6)
 #define NFS_CAP_CASE_PRESERVING	(1U << 7)
+#define NFS_CAP_OFFLOAD_STATUS	(1U << 8)
 #define NFS_CAP_POSIX_LOCK	(1U << 14)
 #define NFS_CAP_UIDGID_NOMAP	(1U << 15)
 #define NFS_CAP_STATEID_NFSV41	(1U << 16)
-- 
2.45.2