On Thu, Oct 03, 2024 at 02:10:20PM +0200, Jan Kara wrote: > On Wed 02-10-24 05:01:03, Matthew Wilcox (Oracle) wrote: > > The mappedtodisk flag is only meaningful for buffer head based > > filesystems. It should not be cleared for other filesystems. This allows > > us to reuse the mappedtodisk flag to have other meanings in filesystems > > that do not use buffer heads. > > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > > The patch looks good. But I'm bit confused about the changelog. There's no > generic code checking for mappedtodisk. Only nilfs2 actually uses it for > anything, all other filesystems just never look at it as far as my grepping > shows. So speaking about "filesystems that do not use buffer heads" looks > somewhat broad to me. Anyway feel free to add: Hmm. f2fs also uses it in page_mkwrite(). But it looks odd to me. Perhaps we could get rid of mappedtodisk entirely ... I see ext4 used to use it until someone removed it in 9ea7df534ed2 ;-) Anyway, what the changelog is trying to say is that only buffer-head filesystems ever have the mappedtodisk flag set, eg by block_read_full_folio() or do_mpage_readpage(). So it doesn't make sense to clear it for non-buffer-head filesystems, and may inhibit their ability to use it for unrelated purposes.
