On Mon, Aug 28, 2023 at 03:54:49PM +0800, Xueshi Hu wrote: > In folio_mark_dirty(), it can automatically fallback to > noop_dirty_folio() if a_ops->dirty_folio is not registered. > > As anon_aops, dev_dax_aops and fb_deferred_io_aops becames empty, remove > them too. I'd put the last sentence as 'In dev_dax_aops and fb_deferred_io_aops replacing .dirty_folio with NULL makes them identical to default (empty_aops) and since we never compare ->a_ops pointer with either of those, we can remove them completely'. There could've been places like #define is_fb_deferred(mapping) (mapping)->a_ops == fb_deferred_io_aops and those would've been broken by that. The fact that there's nothing of that sort in the tree ought to be mentioned in commit message. Note that we *do* have places where method table comparisons are used in predicates like that, so it's not a pure theory; sure, missing that would've probably ended up with broken build, but that can easily be dependent upon the config (and that, alas, is also not a pure theory - BTDT). In this case the change is correct, fortunately... Other than that part of commit message - Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
