On Wed, 2024-03-06 at 08:42 -0500, Jeff Layton wrote: > On Wed, 2024-02-28 at 10:23 +1100, NeilBrown wrote: > > when AOP_WRITEPAGE_ACTIVATE is returned (as NFS does when it detects > > congestion) it is important that the folio is redirtied. > > nfs_writepage_locked() doesn't do this, so files can become corrupted as > > writes can be lost. > > > > Note that this is not needed in v6.8 as AOP_WRITEPAGE_ACTIVATE cannot be > > returned. It is needed for kernels v5.18..v6.7. Prior to 6.3 the patch > > is different as it needs to mention "page", not "folio". > > > > Neil, I have a question about the above statement. In Linus's tree as of > this morning (v6.8-rc7-ish), it does this in nfs_writepages_locked: > > if (wbc->sync_mode == WB_SYNC_NONE && > NFS_SERVER(inode)->write_congested) > return AOP_WRITEPAGE_ACTIVATE; > Sorry, I meant to say: The only caller of nfs_writepages_locked is nfs_wb_folio, and I don't see where it redirties the folio. Why don't we need this in v6.8? > > > Reported-and-tested-by: Jacek Tomaka <Jacek.Tomaka@xxxxxxxxx> > > Fixes: 6df25e58532b ("nfs: remove reliance on bdi congestion") > > Signed-off-by: NeilBrown <neilb@xxxxxxx> > > --- > > fs/nfs/write.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/nfs/write.c b/fs/nfs/write.c > > index b664caea8b4e..9e345d3c305a 100644 > > --- a/fs/nfs/write.c > > +++ b/fs/nfs/write.c > > @@ -668,8 +668,10 @@ static int nfs_writepage_locked(struct folio *folio, > > int err; > > > > if (wbc->sync_mode == WB_SYNC_NONE && > > - NFS_SERVER(inode)->write_congested) > > + NFS_SERVER(inode)->write_congested) { > > + folio_redirty_for_writepage(wbc, folio); > > return AOP_WRITEPAGE_ACTIVATE; > > + } > > > > nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE); > > nfs_pageio_init_write(&pgio, inode, 0, false, > -- Jeff Layton <jlayton@xxxxxxxxxx>