NFSv4.1: Fix some issues with pnfs_generic_pg_test

1. If the intention is to coalesce requests 'prev' and 'req' then we
   have to ensure at least that we have a layout starting at
   req_offset(prev).

2. If we're only requesting a minimal layout of length desc->pg_count,
   we need to test the length actually returned by the server before
   we allow the coalescing to occur.

3. We need to deal correctly with (pgio->lseg == NULL)

4. Fixup the test guarding the pnfs_update_layout.

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

diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index eb4aafa..8ff2ea3 100644 (file)
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -1000,6 +1000,9 @@ static bool objio_pg_test(struct nfs_pageio_descriptor *pgio,
        if (!pnfs_generic_pg_test(pgio, prev, req))
                return false;
 
+       if (pgio->pg_lseg == NULL)
+               return true;
+
        return pgio->pg_count + req->wb_bytes <=
                        OBJIO_LSEG(pgio->pg_lseg)->max_io_size;
 }

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 539b94c..0f42e02 100644 (file)
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1064,19 +1064,21 @@ pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
                gfp_flags = GFP_NOFS;
        }
 
-       if (pgio->pg_count == prev->wb_bytes) {
+       if (pgio->pg_lseg == NULL) {
+               if (pgio->pg_count != prev->wb_bytes)
+                       return true;
                /* This is first coelesce call for a series of nfs_pages */
                pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                                   prev->wb_context,
-                                                  req_offset(req),
+                                                  req_offset(prev),
                                                   pgio->pg_count,
                                                   access_type,
                                                   gfp_flags);
-               return true;
+               if (pgio->pg_lseg == NULL)
+                       return true;
        }
 
-       if (pgio->pg_lseg &&
-           req_offset(req) > end_offset(pgio->pg_lseg->pls_range.offset,
+       if (req_offset(req) > end_offset(pgio->pg_lseg->pls_range.offset,
                                         pgio->pg_lseg->pls_range.length))
                return false;