From 2ca4532a49be92d7b2766c3244b30fa8bfb0114d Mon Sep 17 00:00:00 2001 From: Daisuke Nishimura Date: Mon, 21 Sep 2009 17:02:52 -0700 Subject: mm: add_to_swap_cache() does not return -EEXIST After commit 355cfa73 ("mm: modify swap_map and add SWAP_HAS_CACHE flag"), only the context which have set SWAP_HAS_CACHE flag by swapcache_prepare() or get_swap_page() would call add_to_swap_cache(). So add_to_swap_cache() doesn't return -EEXIST any more. Even though it doesn't return -EEXIST, it's not good behavior conceptually to call swapcache_prepare() in the -EEXIST case, because it means clearing SWAP_HAS_CACHE flag while the entry is on swap cache. This patch removes redundant codes and comments from callers of it, and adds VM_BUG_ON() in error path of add_to_swap_cache() and some comments. Signed-off-by: Daisuke Nishimura Reviewed-by: KAMEZAWA Hiroyuki Cc: Balbir Singh Cc: Hugh Dickins Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/shmem.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'mm/shmem.c') diff --git a/mm/shmem.c b/mm/shmem.c index bd20f8bb02aa..376d8f0a8f6b 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1097,6 +1097,10 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) shmem_swp_unmap(entry); unlock: spin_unlock(&info->lock); + /* + * add_to_swap_cache() doesn't return -EEXIST, so we can safely + * clear SWAP_HAS_CACHE flag. + */ swapcache_free(swap, NULL); redirty: set_page_dirty(page); -- cgit v1.2.3-70-g09d2