From a569469e967022d9ceeaa4b73619f96614087d2d Mon Sep 17 00:00:00 2001 From: Jin Xu Date: Mon, 5 Aug 2013 20:02:04 +0800 Subject: f2fs: fix a deadlock in fsync This patch fixes a deadlock bug that occurs quite often when there are concurrent write and fsync on a same file. Following is the simplified call trace when tasks get hung. fsync thread: - f2fs_sync_file ... - f2fs_write_data_pages ... - update_extent_cache ... - update_inode - wait_on_page_writeback bdi writeback thread - __writeback_single_inode - f2fs_write_data_pages - mutex_lock(sbi->writepages) The deadlock happens when the fsync thread waits on a inode page that has been added to the f2fs' cached bio sbi->bio[NODE], and unfortunately, no one else could be able to submit the cached bio to block layer for writeback. This is because the fsync thread already hold a sbi->fs_lock and the sbi->writepages lock, causing the bdi thread being blocked when attempt to write data pages for the same inode. At the same time, f2fs_gc thread does not notice the situation and could not help. Even the sync syscall gets blocked. To fix it, we could submit the cached bio first before waiting on a inode page that is being written back. Signed-off-by: Jin Xu [Jaegeuk Kim: add more cases to use f2fs_wait_on_page_writeback] Signed-off-by: Jaegeuk Kim --- fs/f2fs/gc.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'fs/f2fs/gc.c') diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index d286d8be8e68..e6b3ffd5ff6a 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -422,8 +422,7 @@ next_step: /* set page dirty and write it */ if (gc_type == FG_GC) { - f2fs_submit_bio(sbi, NODE, true); - wait_on_page_writeback(node_page); + f2fs_wait_on_page_writeback(node_page, NODE, true); set_page_dirty(node_page); } else { if (!PageWriteback(node_page)) @@ -523,10 +522,7 @@ static void move_data_page(struct inode *inode, struct page *page, int gc_type) } else { struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb); - if (PageWriteback(page)) { - f2fs_submit_bio(sbi, DATA, true); - wait_on_page_writeback(page); - } + f2fs_wait_on_page_writeback(page, DATA, true); if (clear_page_dirty_for_io(page) && S_ISDIR(inode->i_mode)) { -- cgit v1.2.3