NFSv4: nfs_client_return_marked_delegations can't flush data

Since even filemap_flush() needs to lock pages that are dirty, we
cannot risk calling it from the state manager context. Therefore,
we need to move the call to filemap_flush() to
nfs_async_inode_return_delegation().

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

1 files changed, 7 insertions, 3 deletions

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index a19cb5ad6b13..bd3a9601d32d 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -316,6 +316,10 @@ out:
  * nfs_client_return_marked_delegations - return previously marked delegations
  * @clp: nfs_client to process
  *
+ * Note that this function is designed to be called by the state
+ * manager thread. For this reason, it cannot flush the dirty data,
+ * since that could deadlock in case of a state recovery error.
+ *
  * Returns zero on success, or a negative errno value.
  */
 int nfs_client_return_marked_delegations(struct nfs_client *clp)
@@ -340,11 +344,9 @@ restart:
                                                                 server);
                         rcu_read_unlock();
 
-                        if (delegation != NULL) {
-                                filemap_flush(inode->i_mapping);
+                        if (delegation != NULL)
                                 err = __nfs_inode_return_delegation(inode,
                                                                 delegation, 0);
-                        }
                         iput(inode);
                         if (!err)
                                 goto restart;
@@ -542,6 +544,8 @@ int nfs_async_inode_return_delegation(struct inode *inode,
         struct nfs_client *clp = server->nfs_client;
         struct nfs_delegation *delegation;
 
+        filemap_flush(inode->i_mapping);
+
         rcu_read_lock();
         delegation = rcu_dereference(NFS_I(inode)->delegation);