--- /dev/null
+From a5faeaf9109578e65e1a32e2a3e76c8b47e7dcb6 Mon Sep 17 00:00:00 2001
+From: Jan Kara <jack@suse.cz>
+Date: Fri, 28 Jun 2013 16:04:02 +0200
+Subject: writeback: Fix periodic writeback after fs mount
+
+From: Jan Kara <jack@suse.cz>
+
+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 <Bert.DeJonghe@amplidata.com>
+Signed-off-by: Jan Kara <jack@suse.cz>
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+
+---
+ fs/block_dev.c | 10 +++++++++-
+ 1 file changed, 9 insertions(+), 1 deletion(-)
+
+--- 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)