nfs: call nfs_can_coalesce_requests for every req

Call nfs_can_coalesce_requests for every request, even the first one.
This is needed for future patches to give pg_test a way to inform
add_request to reduce the size of the request.

Now @prev can be null in nfs_can_coalesce_requests and pg_test functions.

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

1 files changed, 19 insertions, 15 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 82233431880d..f343f49ff596 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -292,6 +292,8 @@ nfs_wait_on_request(struct nfs_page *req)
 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
                            struct nfs_page *prev, struct nfs_page *req)
 {
+        if (!prev)
+                return req->wb_bytes;
         /*
          * FIXME: ideally we should be able to coalesce all requests
          * that are not block boundary aligned, but currently this
@@ -761,17 +763,20 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 {
         size_t size;
 
-        if (!nfs_match_open_context(req->wb_context, prev->wb_context))
-                return false;
-        if (req->wb_context->dentry->d_inode->i_flock != NULL &&
-            !nfs_match_lock_context(req->wb_lock_context, prev->wb_lock_context))
-                return false;
-        if (req->wb_pgbase != 0)
-                return false;
-        if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
-                return false;
-        if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
-                return false;
+        if (prev) {
+                if (!nfs_match_open_context(req->wb_context, prev->wb_context))
+                        return false;
+                if (req->wb_context->dentry->d_inode->i_flock != NULL &&
+                    !nfs_match_lock_context(req->wb_lock_context,
+                                            prev->wb_lock_context))
+                        return false;
+                if (req->wb_pgbase != 0)
+                        return false;
+                if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
+                        return false;
+                if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
+                        return false;
+        }
         size = pgio->pg_ops->pg_test(pgio, prev, req);
         WARN_ON_ONCE(size && size != req->wb_bytes);
         return size > 0;
@@ -788,17 +793,16 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
                                      struct nfs_page *req)
 {
+        struct nfs_page *prev = NULL;
         if (desc->pg_count != 0) {
-                struct nfs_page *prev;
-
                 prev = nfs_list_entry(desc->pg_list.prev);
-                if (!nfs_can_coalesce_requests(prev, req, desc))
-                        return 0;
         } else {
                 if (desc->pg_ops->pg_init)
                         desc->pg_ops->pg_init(desc, req);
                 desc->pg_base = req->wb_pgbase;
         }
+        if (!nfs_can_coalesce_requests(prev, req, desc))
+                return 0;
         nfs_list_remove_request(req);
         nfs_list_add_request(req, &desc->pg_list);
         desc->pg_count += req->wb_bytes;