NFS: Ensure that writepage respects the nonblock flag

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 17 insertions, 6 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 0a6c65a1f9d7..bb72ad34d51d 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -222,7 +222,7 @@ static void nfs_end_page_writeback(struct page *page)
                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
 }
 
-static struct nfs_page *nfs_find_and_lock_request(struct page *page)
+static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
 {
         struct inode *inode = page->mapping->host;
         struct nfs_page *req;
@@ -241,7 +241,10 @@ static struct nfs_page *nfs_find_and_lock_request(struct page *page)
                  *       request as dirty (in which case we don't care).
                  */
                 spin_unlock(&inode->i_lock);
-                ret = nfs_wait_on_request(req);
+                if (!nonblock)
+                        ret = nfs_wait_on_request(req);
+                else
+                        ret = -EAGAIN;
                 nfs_release_request(req);
                 if (ret != 0)
                         return ERR_PTR(ret);
@@ -256,12 +259,12 @@ static struct nfs_page *nfs_find_and_lock_request(struct page *page)
  * 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)
+                                struct page *page, bool nonblock)
 {
         struct nfs_page *req;
         int ret = 0;
 
-        req = nfs_find_and_lock_request(page);
+        req = nfs_find_and_lock_request(page, nonblock);
         if (!req)
                 goto out;
         ret = PTR_ERR(req);
@@ -283,12 +286,20 @@ out:
 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 {
         struct inode *inode = page->mapping->host;
+        int ret;
 
         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 
         nfs_pageio_cond_complete(pgio, page->index);
-        return nfs_page_async_flush(pgio, page);
+        ret = nfs_page_async_flush(pgio, page,
+                        wbc->sync_mode == WB_SYNC_NONE ||
+                        wbc->nonblocking != 0);
+        if (ret == -EAGAIN) {
+                redirty_page_for_writepage(wbc, page);
+                ret = 0;
+        }
+        return ret;
 }
 
 /*
@@ -1546,7 +1557,7 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
 
         nfs_fscache_release_page(page, GFP_KERNEL);
 
-        req = nfs_find_and_lock_request(page);
+        req = nfs_find_and_lock_request(page, false);
         ret = PTR_ERR(req);
         if (IS_ERR(req))
                 goto out;