On Thu 25-07-13 15:27:41, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 3.0-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
This seems as a context problem only. I'll send the backport in a
minute.
Honza
> ------------------ original commit in Linus's tree ------------------
>
> From a5faeaf9109578e65e1a32e2a3e76c8b47e7dcb6 Mon Sep 17 00:00:00 2001
> From: Jan Kara <jack@xxxxxxx>
> Date: Fri, 28 Jun 2013 16:04:02 +0200
> Subject: [PATCH] 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 <Bert.DeJonghe@xxxxxxxxxxxxx>
> CC: stable@xxxxxxxxxxxxxxx # >= 3.0
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 2091db8c..85f5c85e 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.. */
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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