[PATCH 5/6] nfs: Add comment on PG_private use of NFS

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

Add a comment explaining the use of PG_private in the NFS client.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 fs/nfs/write.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6/fs/nfs/write.c
===================================================================
--- linux-2.6.orig/fs/nfs/write.c
+++ linux-2.6/fs/nfs/write.c
@@ -424,6 +424,11 @@ static int nfs_inode_add_request(struct 
 		if (nfs_have_delegation(inode, FMODE_WRITE))
 			nfsi->change_attr++;
 	}
+	/*
+	 * The PG_private bit is unfortunately needed if we want to fix the
+	 * hole in the mmap semantics. If we do not set it, then the VM will
+	 * fail to call the "releasepage" address ops.
+	 */
 	SetPagePrivate(req->wb_page);
 	nfsi->npages++;
 	atomic_inc(&req->wb_count);