From a5faeaf9109578e65e1a32e2a3e76c8b47e7dcb6 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 28 Jun 2013 16:04:02 +0200 Subject: writeback: Fix periodic writeback after fs mount Code in blkdev.c moves a device inode to default_backing_dev_info when the last reference to the device is put and moves the device inode back to its bdi when the first reference is acquired. This includes moving to wb.b_dirty list if the device inode is dirty. The code however doesn't setup timer to wake corresponding flusher thread and while wb.b_dirty list is non-empty __mark_inode_dirty() will not set it up either. Thus periodic writeback is effectively disabled until a sync(2) call which can lead to unexpected data loss in case of crash or power failure. Fix the problem by setting up a timer for periodic writeback in case we add the first dirty inode to wb.b_dirty list in bdev_inode_switch_bdi(). Reported-by: Bert De Jonghe CC: stable@vger.kernel.org # >= 3.0 Signed-off-by: Jan Kara Signed-off-by: Jens Axboe --- fs/block_dev.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/block_dev.c b/fs/block_dev.c index 2091db8cdd78..85f5c85ec91c 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -58,17 +58,24 @@ static void bdev_inode_switch_bdi(struct inode *inode, struct backing_dev_info *dst) { struct backing_dev_info *old = inode->i_data.backing_dev_info; + bool wakeup_bdi = false; if (unlikely(dst == old)) /* deadlock avoidance */ return; bdi_lock_two(&old->wb, &dst->wb); spin_lock(&inode->i_lock); inode->i_data.backing_dev_info = dst; - if (inode->i_state & I_DIRTY) + if (inode->i_state & I_DIRTY) { + if (bdi_cap_writeback_dirty(dst) && !wb_has_dirty_io(&dst->wb)) + wakeup_bdi = true; list_move(&inode->i_wb_list, &dst->wb.b_dirty); + } spin_unlock(&inode->i_lock); spin_unlock(&old->wb.list_lock); spin_unlock(&dst->wb.list_lock); + + if (wakeup_bdi) + bdi_wakeup_thread_delayed(dst); } /* Kill _all_ buffers and pagecache , dirty or not.. */ -- cgit v1.2.1