1 files changed, 13 insertions, 4 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 0cf9d1cd9bd2..89527a487ed7 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -174,8 +174,6 @@ static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int
                 return;
         if (count != nfs_page_length(page))
                 return;
-        if (count != PAGE_CACHE_SIZE)
-                zero_user_page(page, count, PAGE_CACHE_SIZE - count, KM_USER0);
         SetPageUptodate(page);
 }
 
@@ -627,7 +625,8 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
                                 return ERR_PTR(error);
                         }
                         spin_unlock(&inode->i_lock);
-                        return new;
+                        req = new;
+                        goto zero_page;
                 }
                 spin_unlock(&inode->i_lock);
 
@@ -655,13 +654,23 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
         if (offset < req->wb_offset) {
                 req->wb_offset = offset;
                 req->wb_pgbase = offset;
-                req->wb_bytes = rqend - req->wb_offset;
+                req->wb_bytes = max(end, rqend) - req->wb_offset;
+                goto zero_page;
         }
 
         if (end > rqend)
                 req->wb_bytes = end - req->wb_offset;
 
         return req;
+zero_page:
+        /* If this page might potentially be marked as up to date,
+         * then we need to zero any uninitalised data. */
+        if (req->wb_pgbase == 0 && req->wb_bytes != PAGE_CACHE_SIZE
+                        && !PageUptodate(req->wb_page))
+                zero_user_page(req->wb_page, req->wb_bytes,
+                                PAGE_CACHE_SIZE - req->wb_bytes,
+                                KM_USER0);
+        return req;
 }
 
 int nfs_flush_incompatible(struct file *file, struct page *page)