From: Jan Kara Date: Fri, 28 Jun 2013 14:04:02 +0000 (+0200) Subject: writeback: Fix periodic writeback after fs mount X-Git-Tag: v3.0.88~18 X-Git-Url: https://git.fsl.cs.sunysb.edu/?a=commitdiff_plain;h=a4c38fde90666a77d461fd352914f954232361ab;p=unionfs-2.6.39.y.git writeback: Fix periodic writeback after fs mount commit a5faeaf9109578e65e1a32e2a3e76c8b47e7dcb6 upstream. 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 Signed-off-by: Jan Kara Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/block_dev.c b/fs/block_dev.c index 97e4cb5b556..b5eb8c18161 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -55,13 +55,21 @@ EXPORT_SYMBOL(I_BDEV); static void bdev_inode_switch_bdi(struct inode *inode, struct backing_dev_info *dst) { + bool wakeup_bdi = false; + spin_lock(&inode_wb_list_lock); 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(&inode_wb_list_lock); + + if (wakeup_bdi) + bdi_wakeup_thread_delayed(dst); } sector_t blkdev_max_block(struct block_device *bdev)