On 13:31 10/06, Qu Wenruo wrote: > > > On 2020/6/6 上午4:48, Goldwyn Rodrigues wrote: > > In current scenarios, for XFS, it would mean that a page invalidation > > would end up being a writeback error. So, if iomap returns zero, fall > > back to biffered I/O. XFS has never supported fallback to buffered I/O. > > I hope it is not "never will" ;) > > > > With mixed buffered and direct writes in btrfs, the pages may not be > > released the extent may be locked in the ordered extents cleanup thread, > > I'm wondering can we handle this case in a different way. > > In fact btrfs has its own special handling for invalidating pages. > Btrfs will first look for any ordered extents covering the page, finish > the ordered extent manually, then invalidate the page. > > I'm not sure why invalidate_inode_pages2_range() used in dio iomap code > does not use the fs specific invalidatepage(), but only do_lander_page() > then releasepage(). > > Shouldn'y we btrfs implement the lander_page() to handle ordered extents > properly? > Or is there any special requirement? > The problem is aops->launder_page() is called only if PG_Dirty is set. In this case it is not because we just performed a writeback. Also, it is not just ordered ordered extent writeback which may lock the extent, a buffered read can lock as well. -- Goldwyn
Attachment:
signature.asc
Description: PGP signature
