"Darrick J. Wong" <djwong@xxxxxxxxxx> writes: > [add ritesh] > > On Mon, Jul 10, 2023 at 02:02:49PM +0100, Matthew Wilcox (Oracle) wrote: >> The check for the folio being under writeback is unnecessary; the caller >> has checked this and the folio is locked, so the folio cannot be under >> writeback at this point. >> >> The comment is somewhat misleading in that it talks about one specific >> situation in which we can see a dirty folio. There are others, so change >> the comment to explain why we can't release the iomap_page. >> >> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> >> Reviewed-by: Christoph Hellwig <hch@xxxxxx> >> --- >> fs/iomap/buffered-io.c | 9 ++++----- >> 1 file changed, 4 insertions(+), 5 deletions(-) >> >> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c >> index 1cb905140528..7aa3009f907f 100644 >> --- a/fs/iomap/buffered-io.c >> +++ b/fs/iomap/buffered-io.c >> @@ -483,12 +483,11 @@ bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags) >> folio_size(folio)); >> >> /* >> - * mm accommodates an old ext3 case where clean folios might >> - * not have had the dirty bit cleared. Thus, it can send actual >> - * dirty folios to ->release_folio() via shrink_active_list(); >> - * skip those here. >> + * If the folio is dirty, we refuse to release our metadata because >> + * it may be partially dirty. Once we track per-block dirty state, >> + * we can release the metadata if every block is dirty. > > Ritesh: I'm assuming that implementing this will be part of your v12 series? No, if it's any optimization, then I think we can take it up later too, not in v12 please (I have been doing some extensive testing of current series). Also let me understand it a bit more. @willy, Is this what you are suggesting? So this is mainly to free up some memory for iomap_folio_state structure then right? But then whenever we are doing a writeback, we anyway would be allocating iomap_folio_state() and marking all the bits dirty. Isn't it sub-optimal then? @@ -489,8 +489,11 @@ bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags) * it may be partially dirty. Once we track per-block dirty state, * we can release the metadata if every block is dirty. */ - if (folio_test_dirty(folio)) + if (folio_test_dirty(folio)) { + if (ifs_is_fully_dirty(folio, ifs)) + iomap_page_release(folio); return false; + } iomap_page_release(folio); return true; } (Ignore the old and new apis naming in above. It is just to get an idea) -ritesh > > Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> > > --D > >> */ >> - if (folio_test_dirty(folio) || folio_test_writeback(folio)) >> + if (folio_test_dirty(folio)) >> return false; >> iomap_page_release(folio); >> return true; >> -- >> 2.39.2 >>