Re: Function to do end-writeback in bulk

[David Howells <dhowells@redhat.com>]

Matthew Wilcox <willy@infradead.org> wrote:

> I hate this API.  I much prefer the _iter() style:

I'm not that keen on the _iter() style, but whatever.

However, does that make it harder to do the stats manipulation in bulk in
future?

I was looking at __folio_end_writeback(), and I see:

	....
			wb = inode_to_wb(inode);
			wb_stat_mod(wb, WB_WRITEBACK, -nr);
			__wb_writeout_add(wb, nr);
			if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) {
				wb_inode_writeback_end(wb);
				if (mapping->host)
					sb_clear_inode_writeback(mapping->host);
			}
	...
		lruvec_stat_mod_folio(folio, NR_WRITEBACK, -nr);
		zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
		node_stat_mod_folio(folio, NR_WRITTEN, nr);
	...

And I was thinking those could be done in bulk... but there seems to be an IRQ
disablement requirement around them.  Does the folio_xor_flags_has_waiters()
have to be done inside?  I presume this is to prevent a set/clear race on the
master WRITEBACK tag.

David