NFS: Fix a deadlock with lazy umount

We can't allow rpc callback functions like task->tk_ops->rpc_call_prepare()
and task->tk_ops->rpc_call_done() to call mntput() in any way, since
that will cause a deadlock when the call to rpc_shutdown_client() attempts
to wait on 'task' to complete.

We can avoid the above deadlock by moving calls to mntput to
task->tk_ops->rpc_release() callback, since at that time the task will be
marked as completed, and so rpc_shutdown_client won't attempt to wait on
it.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 16844f98f50e..e0170407a885 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -323,7 +323,7 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
                 data->inode = inode;
                 data->cred = msg.rpc_cred;
                 data->args.fh = NFS_FH(inode);
-                data->args.context = ctx;
+                data->args.context = get_nfs_open_context(ctx);
                 data->args.offset = pos;
                 data->args.pgbase = pgbase;
                 data->args.pages = data->pagevec;
@@ -546,6 +546,7 @@ static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
         data->args.fh = NFS_FH(data->inode);
         data->args.offset = 0;
         data->args.count = 0;
+        data->args.context = get_nfs_open_context(dreq->ctx);
         data->res.count = 0;
         data->res.fattr = &data->fattr;
         data->res.verf = &data->verf;
@@ -728,7 +729,7 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
                 data->inode = inode;
                 data->cred = msg.rpc_cred;
                 data->args.fh = NFS_FH(inode);
-                data->args.context = ctx;
+                data->args.context = get_nfs_open_context(ctx);
                 data->args.offset = pos;
                 data->args.pgbase = pgbase;
                 data->args.pages = data->pagevec;