nfs: modify pg_test interface to return size_t

This is a step toward allowing pg_test to inform the the
coalescing code to reduce the size of requests so they may fit in
whatever scheme the pg_test callback wants to define.

For now, just return the size of the request if there is space, or 0
if there is not.  This shouldn't change any behavior as it acts
the same as when the pg_test functions returned bool.

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

1 files changed, 9 insertions, 3 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 0fe670189fd1..de6eb16f94d1 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1434,7 +1434,11 @@ pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,
 }
 EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_write);
 
-bool
+/*
+ * Return 0 if @req cannot be coalesced into @pgio, otherwise return the number
+ * of bytes (maximum @req->wb_bytes) that can be coalesced.
+ */
+size_t
 pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 		     struct nfs_page *req)
 {
@@ -1455,8 +1459,10 @@ pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 	 * first byte that lies outside the pnfs_layout_range. FIXME?
 	 *
 	 */
-	return req_offset(req) < end_offset(pgio->pg_lseg->pls_range.offset,
-					 pgio->pg_lseg->pls_range.length);
+	if (req_offset(req) < end_offset(pgio->pg_lseg->pls_range.offset,
+					 pgio->pg_lseg->pls_range.length))
+		return req->wb_bytes;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);