[PATCH] NFS: Make searching and waiting on busy writeback requests more efficient.

 Basically copies the VFS's method for tracking writebacks and applies
 it to the struct nfs_page.

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

1 files changed, 28 insertions, 1 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 80777f99a58a..356a33bb38a6 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -112,6 +112,33 @@ void nfs_unlock_request(struct nfs_page *req)
 }
 
 /**
+ * nfs_set_page_writeback_locked - Lock a request for writeback
+ * @req:
+ */
+int nfs_set_page_writeback_locked(struct nfs_page *req)
+{
+	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
+
+	if (!nfs_lock_request(req))
+		return 0;
+	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
+	return 1;
+}
+
+/**
+ * nfs_clear_page_writeback - Unlock request and wake up sleepers
+ */
+void nfs_clear_page_writeback(struct nfs_page *req)
+{
+	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
+
+	spin_lock(&nfsi->req_lock);
+	radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
+	spin_unlock(&nfsi->req_lock);
+	nfs_unlock_request(req);
+}
+
+/**
  * nfs_clear_request - Free up all resources allocated to the request
  * @req:
  *
@@ -301,7 +328,7 @@ nfs_scan_list(struct list_head *head, struct list_head *dst,
 		if (req->wb_index > idx_end)
 			break;
 
-		if (!nfs_lock_request(req))
+		if (!nfs_set_page_writeback_locked(req))
 			continue;
 		nfs_list_remove_request(req);
 		nfs_list_add_request(req, dst);