From 9a01b56b1a79e210e9d2d67c9b18906d31d536c4 Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Sun, 7 Sep 2014 11:05:20 +0800 Subject: [PATCH] f2fs: avoid node page to be written twice in gc_node_segment In gc_node_segment, if node page gc is run concurrently with node page writeback, and check_valid_map and get_node_page run after page locked and before cur_valid_map is updated as below, it is possible for the page to be written twice unnecessarily. sync_node_pages try_lock_page ... check_valid_map f2fs_write_node_page ... write_node_page do_write_page allocate_data_block ... refresh_sit_entry /* update cur_valid_map */ ... ... unlock_page get_node_page ... set_page_dirty ... f2fs_put_page unlock_page This can be solved via calling check_valid_map after get_node_page again. Signed-off-by: Huang, Ying Signed-off-by: Jaegeuk Kim --- fs/f2fs/gc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 943a31db7cc3..075ea1eb8fa0 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -423,6 +423,12 @@ next_step: if (IS_ERR(node_page)) continue; + /* block may become invalid during get_node_page */ + if (check_valid_map(sbi, segno, off) == 0) { + f2fs_put_page(node_page, 1); + continue; + } + /* set page dirty and write it */ if (gc_type == FG_GC) { f2fs_wait_on_page_writeback(node_page, NODE);