Re: [patch 2/4] vfs: add set_page_dirty_notag
From: Andrew Morton
Date: Tue Feb 17 2009 - 19:38:47 EST
On Wed, 18 Feb 2009 03:26:16 +0300
Edward Shishkin <edward.shishkin@xxxxxxxxx> wrote:
> Andrew Morton wrote:
> > On Tue, 17 Feb 2009 01:43:28 +0300
> > Edward Shishkin <edward.shishkin@xxxxxxxxx> wrote:
> >
> >
> >> + */
> >> +int set_page_dirty_notag(struct page *page)
> >> +{
> >> + struct address_space *mapping = page->mapping;
> >> +
> >> + if (!TestSetPageDirty(page)) {
> >> + WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
> >> + if (mapping_cap_account_dirty(mapping)) {
> >> + /*
> >> + * The accounting functions rely on
> >> + * being atomic wrt interrupts.
> >> + */
> >> + unsigned long flags;
> >> + local_irq_save(flags);
> >> + __inc_zone_page_state(page, NR_FILE_DIRTY);
> >> + __inc_bdi_stat(mapping->backing_dev_info,
> >> + BDI_RECLAIMABLE);
> >> + task_dirty_inc(current);
> >> + task_io_account_write(PAGE_CACHE_SIZE);
> >> + local_irq_restore(flags);
> >> + }
> >> + __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
> >> + return 1;
> >> + }
> >> + return 0;
> >> +}
> >>
> >
> > I'll maintain this in -mm, alongside the resier4 patches which need it.
> >
> > Of course, this rather obviates the purpose - if someone changes, say,
> > __set_page_dirty_nobuffers() then they won't similarly update
> > set_page_dirty_notag(). Oh well.
> >
> > This problem would fix itself if those two functions were to
> > substantially share code.
>
> It will fix the problem only partially:
> there is one more friend __set_page_dirty() in buffer.c
But all three functions do the same thing?
if (mapping_cap_account_dirty(mapping)) {
__inc_zone_page_state(page, NR_FILE_DIRTY);
__inc_bdi_stat(mapping->backing_dev_info,
BDI_RECLAIMABLE);
task_dirty_inc(current);
task_io_account_write(PAGE_CACHE_SIZE);
}
?
> Maybe it makes sense to add comments with warnings
> in all such places, or create a header file with a static inline
> function update_page_accounting() ?
Could just uninline the helper function I guess - if you look, those
four statements already involve doing a heck of a lot of stuff.
Try it, see how it looks?
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