在 2020/4/27 20:28:36, "Matthew Wilcox" <willy@xxxxxxxxxxxxx> 写道: >On Mon, Apr 27, 2020 at 04:47:42PM +0800, Shiyang Ruan wrote: >> This patchset is a try to resolve the shared 'page cache' problem for >> fsdax. >> >> In order to track multiple mappings and indexes on one page, I >> introduced a dax-rmap rb-tree to manage the relationship. A dax entry >> will be associated more than once if is shared. At the second time we >> associate this entry, we create this rb-tree and store its root in >> page->private(not used in fsdax). Insert (->mapping, ->index) when >> dax_associate_entry() and delete it when dax_disassociate_entry(). > >Do we really want to track all of this on a per-page basis? I would >have thought a per-extent basis was more useful. Essentially, create >a new address_space for each shared extent. Per page just seems like >a huge overhead. > Per-extent tracking is a nice idea for me. I haven't thought of it yet... But the extent info is maintained by filesystem. I think we need a way to obtain this info from FS when associating a page. May be a bit complicated. Let me think about it... -- Thanks, Ruan Shiyang.
