[RFC PATCH 17/17] netfs: Combine prepare and issue ops and grab the buffers on request

[ChenXiaoSong]

Hi David,

https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?h=netfs-next&id=a99af9686490fa9a099679bcbfa1b56c839b8d98

I reviewed this patch in your repository's netfs-next branch (it looks 
slightly different from the version posted to the mailing list) and 
found two issues, the following additional changes are needed:

```
--- a/fs/netfs/direct_write.c
+++ b/fs/netfs/direct_write.c
@@ -161,8 +161,8 @@ static int netfs_unbuffered_write(struct 
netfs_io_request *wreq)
                                         break;
                                 }
                                 netfs_put_subrequest(subreq, 
netfs_sreq_trace_put_failed);
-                               subreq = NULL;
                                 ret = subreq->error;
+                               subreq = NULL;
                                 goto failed;
                         }
                         break;
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index 697a47e96d2a..112363f17a84 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -808,6 +808,7 @@ struct netfs_writethrough 
*netfs_begin_writethrough(struct kiocb *iocb, size_t l
         if (bvecq_buffer_init(&wreq->load_cursor, GFP_NOFS) < 0) {
                 netfs_put_failed_request(wreq);
                 mutex_unlock(&ictx->wb_lock);
+               kfree(wthru);
                 return ERR_PTR(-ENOMEM);
         }
```