Re: [PATCH V2] vfs: re-implement writeback_inodes_sb(_nr)_if_idle()and rename them

From: Fengguang Wu
Date: Fri Jan 11 2013 - 21:53:53 EST


On Fri, Jan 11, 2013 at 09:12:11PM +0100, Jan Kara wrote:
> On Thu 10-01-13 13:47:57, Miao Xie wrote:
> > writeback_inodes_sb(_nr)_if_idle() is re-implemented by replacing down_read()
> > with down_read_trylock() because
> > - If ->s_umount is write locked, then the sb is not idle. That is
> > writeback_inodes_sb(_nr)_if_idle() needn't wait for the lock.
> > - writeback_inodes_sb(_nr)_if_idle() grabs s_umount lock when it want to start
> > writeback, it may bring us deadlock problem when doing umount. In order to
> > fix the problem, ext4 and btrfs implemented their own writeback functions
> > instead of writeback_inodes_sb(_nr)_if_idle(), but it introduced the redundant
> > code, it is better to implement a new writeback_inodes_sb(_nr)_if_idle().
> >
> > The name of these two functions is cumbersome, so rename them to
> > try_to_writeback_inodes_sb(_nr).
> >
> > This idea came from Christoph Hellwig.
> > Some code is from the patch of Kamal Mostafa.
> The patch looks good. Thanks! You can add:
> Reviewed-by: Jan Kara <jack@xxxxxxx>
>
> BTW, since changes to filesystems are minimal, maybe Fengguang can take
> the patch through his writeback tree? Fengguang?

OK, done. The patch looks good, thanks!

Fengguang
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