f2fs: do not make dirty any inmemory pages

This patch let inmemory pages be clean all the time.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 923cb76..9d4a7ab 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -178,7 +178,8 @@
 {
 	struct f2fs_inode_info *fi = F2FS_I(inode);
 	struct inmem_pages *new;
-
+	int err;
+retry:
 	new = f2fs_kmem_cache_alloc(inmem_entry_slab, GFP_NOFS);
 
 	/* add atomic page indices to the list */
@@ -187,6 +188,16 @@
 
 	/* increase reference count with clean state */
 	mutex_lock(&fi->inmem_lock);
+	err = radix_tree_insert(&fi->inmem_root, page->index, new);
+	if (err == -EEXIST) {
+		mutex_unlock(&fi->inmem_lock);
+		kmem_cache_free(inmem_entry_slab, new);
+		return;
+	} else if (err) {
+		mutex_unlock(&fi->inmem_lock);
+		kmem_cache_free(inmem_entry_slab, new);
+		goto retry;
+	}
 	get_page(page);
 	list_add_tail(&new->list, &fi->inmem_pages);
 	mutex_unlock(&fi->inmem_lock);
@@ -216,6 +227,7 @@
 			do_write_data_page(cur->page, &fio);
 			submit_bio = true;
 		}
+		radix_tree_delete(&fi->inmem_root, cur->page->index);
 		f2fs_put_page(cur->page, 1);
 		list_del(&cur->list);
 		kmem_cache_free(inmem_entry_slab, cur);