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>

3 files changed, 30 insertions, 21 deletions

diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 9cea9358fe52..7a665e0f35b7 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/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
diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index 71b9c69dbe9c..611320753db2 100644
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/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)
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index de6eb16f94d1..354c53cd4095 100644
--- a/fs/nfs/pnfs.c
+++ b/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);