On Thu, Mar 23, 2023 at 03:26:43AM +0000, Matthew Wilcox wrote: > On Mon, Mar 06, 2023 at 02:40:55PM +0530, Ritesh Harjani wrote: > > "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> writes: > > > > > Prepare ext4 to support large folios in the page writeback path. > > > > Sure. I am guessing for ext4 to completely support large folio > > requires more work like fscrypt bounce page handling doesn't > > yet support folios right? > > > > Could you please give a little background on what all would be required > > to add large folio support in ext4 buffered I/O path? > > (I mean ofcourse other than saying move ext4 to iomap ;)) > > > > What I was interested in was, what other components in particular for > > e.g. fscrypt, fsverity, ext4's xyz component needs large folio support? > > > > And how should one go about in adding this support? So can we move > > ext4's read path to have large folio support to get started? > > Have you already identified what all is missing from this path to > > convert it? > > Honestly, I don't know what else needs to be done beyond this patch > series. I can point at some stuff and say "This doesn't work", but in > general, you have to just enable it and see what breaks. A lot of the > buffer_head code is not large-folio safe right now, so that's somewhere > to go and look. Or maybe we "just" convert to iomap, and never bother > fixing the bufferhead code for large folios. Yes. Let's leave bufferheads in the legacy doo-doo-dooooo basement instead of wasting more time on them. Ideally we'd someday run all the filesystems through: bufferheads -> iomap with bufferheads -> iomap with folios -> iomap with large folios -> retire to somewhere cheaper than Hawaii --D > > > Also set the actual error in the mapping, not just -EIO. > > > > Right. I looked at the history and I think it always just had EIO. > > I think setting the actual err in mapping_set_error() is the right thing > > to do here. > > > > > > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > > > > w.r.t this patch series. I reviewed the mechanical changes & error paths > > which converts ext4 ext4_finish_bio() to use folio. > > > > The changes looks good to me from that perspective. Feel free to add - > > Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> > > Thanks!
