nfs: only remove page from mapping if launder_page fails

Instead of dropping pages when write fails, only do it when
we get fatal failure in launder_page write back.

Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

3 files changed, 37 insertions, 18 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 93e236429c5d..f188dd071dfc 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -545,7 +545,7 @@ static int nfs_launder_page(struct page *page)
                 inode->i_ino, (long long)page_offset(page));
 
         nfs_fscache_wait_on_page_write(nfsi, page);
-        return nfs_wb_page(inode, page);
+        return nfs_wb_launder_page(inode, page);
 }
 
 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 9dafb08ddae5..4d254232d728 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -559,7 +559,8 @@ static void nfs_write_error_remove_page(struct nfs_page *req)
  * May return an error if the user signalled nfs_wait_on_request().
  */
 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
-                                struct page *page, bool nonblock)
+                                struct page *page, bool nonblock,
+                                bool launder)
 {
         struct nfs_page *req;
         int ret = 0;
@@ -578,17 +579,19 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
         if (!nfs_pageio_add_request(pgio, req)) {
                 ret = pgio->pg_error;
                 /*
-                 * Remove the problematic req upon fatal errors,
-                 * while other dirty pages can still be around
-                 * until they get flushed.
+                 * Remove the problematic req upon fatal errors
+                 * in launder case, while other dirty pages can
+                 * still be around until they get flushed.
                  */
                 if (nfs_error_is_fatal(ret)) {
                         nfs_context_set_write_error(req->wb_context, ret);
-                        nfs_write_error_remove_page(req);
-                } else {
-                        nfs_redirty_request(req);
-                        ret = -EAGAIN;
+                        if (launder) {
+                                nfs_write_error_remove_page(req);
+                                goto out;
+                        }
                 }
+                nfs_redirty_request(req);
+                ret = -EAGAIN;
         } else
                 nfs_add_stats(page_file_mapping(page)->host,
                                 NFSIOS_WRITEPAGES, 1);
@@ -596,12 +599,14 @@ out:
         return ret;
 }
 
-static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
+static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
+                            struct nfs_pageio_descriptor *pgio, bool launder)
 {
         int ret;
 
         nfs_pageio_cond_complete(pgio, page_file_index(page));
-        ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
+        ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE,
+                                   launder);
         if (ret == -EAGAIN) {
                 redirty_page_for_writepage(wbc, page);
                 ret = 0;
@@ -612,7 +617,9 @@ static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, st
 /*
  * Write an mmapped page to the server.
  */
-static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
+static int nfs_writepage_locked(struct page *page,
+                                struct writeback_control *wbc,
+                                bool launder)
 {
         struct nfs_pageio_descriptor pgio;
         struct inode *inode = page_file_mapping(page)->host;
@@ -621,7 +628,7 @@ static int nfs_writepage_locked(struct page *page, struct writeback_control *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);
+        err = nfs_do_writepage(page, wbc, &pgio, launder);
         nfs_pageio_complete(&pgio);
         if (err < 0)
                 return err;
@@ -634,7 +641,7 @@ int nfs_writepage(struct page *page, struct writeback_control *wbc)
 {
         int ret;
 
-        ret = nfs_writepage_locked(page, wbc);
+        ret = nfs_writepage_locked(page, wbc, false);
         unlock_page(page);
         return ret;
 }
@@ -643,7 +650,7 @@ static int nfs_writepages_callback(struct page *page, struct writeback_control *
 {
         int ret;
 
-        ret = nfs_do_writepage(page, wbc, data);
+        ret = nfs_do_writepage(page, wbc, data, false);
         unlock_page(page);
         return ret;
 }
@@ -1931,7 +1938,7 @@ int nfs_wb_page_cancel(struct inode *inode, struct page *page)
 /*
  * Write back all requests on one page - we do this before reading it.
  */
-int nfs_wb_page(struct inode *inode, struct page *page)
+int nfs_wb_single_page(struct inode *inode, struct page *page, bool launder)
 {
         loff_t range_start = page_file_offset(page);
         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
@@ -1948,7 +1955,7 @@ int nfs_wb_page(struct inode *inode, struct page *page)
         for (;;) {
                 wait_on_page_writeback(page);
                 if (clear_page_dirty_for_io(page)) {
-                        ret = nfs_writepage_locked(page, &wbc);
+                        ret = nfs_writepage_locked(page, &wbc, launder);
                         if (ret < 0)
                                 goto out_error;
                         continue;
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index c0e961474a52..b88fc46cfbb8 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -517,13 +517,25 @@ extern int  nfs_updatepage(struct file *, struct page *, unsigned int, unsigned
  */
 extern int nfs_sync_inode(struct inode *inode);
 extern int nfs_wb_all(struct inode *inode);
-extern int nfs_wb_page(struct inode *inode, struct page* page);
+extern int nfs_wb_single_page(struct inode *inode, struct page *page, bool launder);
 extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
 extern int  nfs_commit_inode(struct inode *, int);
 extern struct nfs_commit_data *nfs_commitdata_alloc(void);
 extern void nfs_commit_free(struct nfs_commit_data *data);
 
 static inline int
+nfs_wb_launder_page(struct inode *inode, struct page *page)
+{
+        return nfs_wb_single_page(inode, page, true);
+}
+
+static inline int
+nfs_wb_page(struct inode *inode, struct page *page)
+{
+        return nfs_wb_single_page(inode, page, false);
+}
+
+static inline int
 nfs_have_writebacks(struct inode *inode)
 {
         return NFS_I(inode)->nrequests != 0;