NFS41: send real write size in layoutget

For buffer write, block layout client scan inode mapping to find
next hole and use offset-to-hole as layoutget length. Object
layout client uses offset-to-isize as layoutget length.

For direct write, both block layout and object layout use dreq->bytes_left.

Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 35 insertions, 3 deletions

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index a34014a7f9a5..f1027b06a1a9 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -37,6 +37,7 @@
 #include <linux/bio.h>          /* struct bio */
 #include <linux/buffer_head.h>  /* various write calls */
 #include <linux/prefetch.h>
+#include <linux/pagevec.h>
 
 #include "../pnfs.h"
 #include "../internal.h"
@@ -1204,14 +1205,45 @@ bl_pg_test_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
         return pnfs_generic_pg_test(pgio, prev, req);
 }
 
+/*
+ * Return the number of contiguous bytes for a given inode
+ * starting at page frame idx.
+ */
+static u64 pnfs_num_cont_bytes(struct inode *inode, pgoff_t idx)
+{
+        struct address_space *mapping = inode->i_mapping;
+        pgoff_t end;
+
+        /* Optimize common case that writes from 0 to end of file */
+        end = DIV_ROUND_UP(i_size_read(inode), PAGE_CACHE_SIZE);
+        if (end != NFS_I(inode)->npages) {
+                rcu_read_lock();
+                end = radix_tree_next_hole(&mapping->page_tree, idx + 1, ULONG_MAX);
+                rcu_read_unlock();
+        }
+
+        if (!end)
+                return i_size_read(inode) - (idx << PAGE_CACHE_SHIFT);
+        else
+                return (end - idx) << PAGE_CACHE_SHIFT;
+}
+
 static void
 bl_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
 {
         if (pgio->pg_dreq != NULL &&
-            !is_aligned_req(req, PAGE_CACHE_SIZE))
+            !is_aligned_req(req, PAGE_CACHE_SIZE)) {
                 nfs_pageio_reset_write_mds(pgio);
-        else
-                pnfs_generic_pg_init_write(pgio, req);
+        } else {
+                u64 wb_size;
+                if (pgio->pg_dreq == NULL)
+                        wb_size = pnfs_num_cont_bytes(pgio->pg_inode,
+                                                      req->wb_index);
+                else
+                        wb_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+
+                pnfs_generic_pg_init_write(pgio, req, wb_size);
+        }
 }
 
 static bool