nfs: chain calls to pg_test

Now that pg_test can change the size of the request (by returning a non-zero
size smaller than the request), pg_test functions that call other
pg_test functions must return the minimum of the result - or 0 if any fail.

Also clean up the logic of some pg_test functions so that all checks are
for contitions where coalescing is not possible.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/nfs4filelayout.c

@@ -928,26 +928,27 @@ static size_t
 filelayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 		   struct nfs_page *req)
 {
+	unsigned int size;
 	u64 p_stripe, r_stripe;
 	u32 stripe_unit;
 
-	if (!pnfs_generic_pg_test(pgio, prev, req) ||
-	    !nfs_generic_pg_test(pgio, prev, req))
+	/* calls nfs_generic_pg_test */
+	size = pnfs_generic_pg_test(pgio, prev, req);
+	if (!size)
 		return 0;
 
-	if (!prev)
-		return req->wb_bytes;
+	if (prev) {
+		p_stripe = (u64)req_offset(prev);
+		r_stripe = (u64)req_offset(req);
+		stripe_unit = FILELAYOUT_LSEG(pgio->pg_lseg)->stripe_unit;
 
-	p_stripe = (u64)req_offset(prev);
-	r_stripe = (u64)req_offset(req);
-	stripe_unit = FILELAYOUT_LSEG(pgio->pg_lseg)->stripe_unit;
+		do_div(p_stripe, stripe_unit);
+		do_div(r_stripe, stripe_unit);
 
-	do_div(p_stripe, stripe_unit);
-	do_div(r_stripe, stripe_unit);
-
-	if (p_stripe == r_stripe)
-		return req->wb_bytes;
-	return 0;
+		if (p_stripe != r_stripe)
+			return 0;
+	}
+	return min(size, req->wb_bytes);
 }
 
 static void

fs/nfs/objlayout/objio_osd.c

@@ -571,12 +571,15 @@ int objio_write_pagelist(struct nfs_pgio_data *wdata, int how)
 static size_t objio_pg_test(struct nfs_pageio_descriptor *pgio,
 			  struct nfs_page *prev, struct nfs_page *req)
 {
-	if (!pnfs_generic_pg_test(pgio, prev, req) ||
-	    pgio->pg_count + req->wb_bytes >
+	unsigned int size;
+
+	size = pnfs_generic_pg_test(pgio, prev, req);
+
+	if (!size || pgio->pg_count + req->wb_bytes >
 	    (unsigned long)pgio->pg_layout_private)
 		return 0;
 
-	return req->wb_bytes;
+	return min(size, req->wb_bytes);
 }
 
 static void objio_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)

fs/nfs/pnfs.c

@@ -1442,8 +1442,12 @@ size_t
 pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 		     struct nfs_page *req)
 {
-	if (pgio->pg_lseg == NULL)
-		return nfs_generic_pg_test(pgio, prev, req);
+	unsigned int size;
+
+	size = nfs_generic_pg_test(pgio, prev, req);
+
+	if (!size)
+		return 0;
 
 	/*
 	 * Test if a nfs_page is fully contained in the pnfs_layout_range.
@@ -1459,10 +1463,11 @@ pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 	 * first byte that lies outside the pnfs_layout_range. FIXME?
 	 *
 	 */
-	if (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 req->wb_bytes;
-	return 0;
+		return 0;
+
+	return min(size, req->wb_bytes);
 }
 EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);