On Fri, Sep 11 2009, Christoph Hellwig wrote:
> > -static struct bdi_work *bdi_alloc_work(struct writeback_control *wbc)
> > +static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
> > + struct writeback_control *wbc)
> > {
> > struct bdi_work *work;
> >
> > @@ -195,7 +196,7 @@ static struct bdi_work *bdi_alloc_work(struct writeback_control *wbc)
> > if (work)
> > bdi_work_init(work, wbc);
> >
> > - return work;
> > + bdi_queue_work(bdi, work);
>
> This is now the only caller of bdi_queue_work that has a NULL work
> argument. I would recommend removing the !work half of bdi_queue_work
> and just inline it into this function (or make it a separate helper).
Yep agreed.
> > /*
> > + * Schedule writeback for all backing devices. Can only be used for
> > + * WB_SYNC_NONE writeback, WB_SYNC_ALL should use bdi_start_writeback()
> > + * and pass in the superblock.
> > */
> > static void bdi_writeback_all(struct writeback_control *wbc)
> > {
> > struct backing_dev_info *bdi;
> >
> > + WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
> > +
> > spin_lock(&bdi_lock);
> >
> > list_for_each_entry(bdi, &bdi_list, bdi_list) {
> > if (!bdi_has_dirty_io(bdi))
> > continue;
> >
> > + bdi_alloc_queue_work(bdi, wbc);
> > }
>
>
> Much nicer than before. Could be even further simplified to:
>
> if (bdi_has_dirty_io(bdi))
> bdi_alloc_queue_work(bdi, wbc);
Sure, matter of style.
> > @@ -1157,6 +1115,7 @@ long sync_inodes_sb(struct super_block *sb)
> > {
> > struct writeback_control wbc = {
> > .sb = sb,
> > + .bdi = sb->s_bdi,
> > .sync_mode = WB_SYNC_ALL,
> > .range_start = 0,
> > .range_end = LLONG_MAX,
> > @@ -1164,7 +1123,7 @@ long sync_inodes_sb(struct super_block *sb)
> > long nr_to_write = LONG_MAX; /* doesn't actually matter */
> >
> > wbc.nr_to_write = nr_to_write;
> > - bdi_writeback_all(&wbc);
> > + bdi_start_writeback(&wbc);
>
> So here we have a WB_SYNC_ALL caller of bdi_writeback_all and the
> only other caller is WB_SYNC_NONE. Given that after patch two those
> are entirely different codepathes in bdi_start_writeback I would just
> split bdi_start_writeback into two separate functions.
Sure, it'll draw a sharper line between WB_SYNC_NONE and WB_SYNC_ALL.
I'll work on this and the bdi cap dirty flag removal as a follow up.
--
Jens Axboe
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