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>
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 966a885..a499fb5 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -521,8 +521,12 @@
static void __put_nfs_open_context(struct nfs_open_context *ctx, int wait)
{
- struct inode *inode = ctx->path.dentry->d_inode;
+ struct inode *inode;
+ if (ctx == NULL)
+ return;
+
+ inode = ctx->path.dentry->d_inode;
if (!atomic_dec_and_lock(&ctx->count, &inode->i_lock))
return;
list_del(&ctx->list);