NFS: Fix up page writeback accounting

Currently, we are crediting all the calls to nfs_writepages_callback()
(i.e. the nfs_writepages() callback) to nfs_writepage(). Aside from
being inconsistent with the behaviour of the equivalent readpage/readpages
accounting, this also means that we cannot distinguish between bulk writes
and single page writebacks (which confuses the 'nfsiostat -p' tool).

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 72624dc4a623..cfa47761a8ce 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -569,19 +569,17 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
         if (!nfs_pageio_add_request(pgio, req)) {
                 nfs_redirty_request(req);
                 ret = pgio->pg_error;
-        }
+        } else
+                nfs_add_stats(page_file_mapping(page)->host,
+                                NFSIOS_WRITEPAGES, 1);
 out:
         return ret;
 }
 
 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 {
-        struct inode *inode = page_file_mapping(page)->host;
         int ret;
 
-        nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
-        nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
-
         nfs_pageio_cond_complete(pgio, page_file_index(page));
         ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
         if (ret == -EAGAIN) {
@@ -597,9 +595,11 @@ static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, st
 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 {
         struct nfs_pageio_descriptor pgio;
+        struct inode *inode = page_file_mapping(page)->host;
         int err;
 
-        nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc),
+        nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
+        nfs_pageio_init_write(&pgio, inode, wb_priority(wbc),
                                 false, &nfs_async_write_completion_ops);
         err = nfs_do_writepage(page, wbc, &pgio);
         nfs_pageio_complete(&pgio);