nfs: support page groups in nfs_read_completion

nfs_read_completion relied on the fact that there was a 1:1 mapping
of page to nfs_request, but this has now changed.

Regions not covered by a request have already been zeroed elsewhere.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 17 insertions, 7 deletions

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 53d5b83611ce..e818a475ca64 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -130,7 +130,6 @@ static void nfs_page_group_set_uptodate(struct nfs_page *req)
                 SetPageUptodate(req->wb_page);
 }
 
-/* Note io was page aligned */
 static void nfs_read_completion(struct nfs_pgio_header *hdr)
 {
         unsigned long bytes = 0;
@@ -140,14 +139,25 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
         while (!list_empty(&hdr->pages)) {
                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
                 struct page *page = req->wb_page;
+                unsigned long start = req->wb_pgbase;
+                unsigned long end = req->wb_pgbase + req->wb_bytes;
 
                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
-                        if (bytes > hdr->good_bytes)
-                                zero_user(page, 0, PAGE_SIZE);
-                        else if (hdr->good_bytes - bytes < PAGE_SIZE)
-                                zero_user_segment(page,
-                                        hdr->good_bytes & ~PAGE_MASK,
-                                        PAGE_SIZE);
+                        /* note: regions of the page not covered by a
+                         * request are zeroed in nfs_readpage_async /
+                         * readpage_async_filler */
+                        if (bytes > hdr->good_bytes) {
+                                /* nothing in this request was good, so zero
+                                 * the full extent of the request */
+                                zero_user_segment(page, start, end);
+
+                        } else if (hdr->good_bytes - bytes < req->wb_bytes) {
+                                /* part of this request has good bytes, but
+                                 * not all. zero the bad bytes */
+                                start += hdr->good_bytes - bytes;
+                                WARN_ON(start < req->wb_pgbase);
+                                zero_user_segment(page, start, end);
+                        }
                 }
                 bytes += req->wb_bytes;
                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {