NFS: Don't fail an O_DIRECT read/write if get_user_pages() returns pages

There is no need to fail the entire O_DIRECT read/write just because
get_user_pages() returned fewer pages than we requested.

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

1 files changed, 16 insertions, 6 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 4c97e55e86ee..f1b153ad645b 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -295,9 +295,14 @@ static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned lo
                         break;
                 }
                 if ((unsigned)result < data->npages) {
-                        nfs_direct_release_pages(data->pagevec, result);
-                        nfs_readdata_release(data);
-                        break;
+                        bytes = result * PAGE_SIZE;
+                        if (bytes <= pgbase) {
+                                nfs_direct_release_pages(data->pagevec, result);
+                                nfs_readdata_release(data);
+                                break;
+                        }
+                        bytes -= pgbase;
+                        data->npages = result;
                 }
 
                 get_dreq(dreq);
@@ -630,9 +635,14 @@ static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned l
                         break;
                 }
                 if ((unsigned)result < data->npages) {
-                        nfs_direct_release_pages(data->pagevec, result);
-                        nfs_writedata_release(data);
-                        break;
+                        bytes = result * PAGE_SIZE;
+                        if (bytes <= pgbase) {
+                                nfs_direct_release_pages(data->pagevec, result);
+                                nfs_writedata_release(data);
+                                break;
+                        }
+                        bytes -= pgbase;
+                        data->npages = result;
                 }
 
                 get_dreq(dreq);