On Mon, Jun 22, 2020 at 8:13 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > > I'm fine with not moving that functionality into the VFS. The problem > > I have in gfs2 is that taking glocks is really expensive. Part of that > > overhead is accidental, but we definitely won't be able to fix it in > > the short term. So something like the IOCB_CACHED flag that prevents > > generic_file_read_iter from issuing readahead I/O would save the day > > for us. Does that idea stand a chance? > > For the short-term fix, is switching to a trylock in gfs2_readahead() > acceptable? Well, it's the only thing we can do for now, right? > diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c > index 72c9560f4467..6ccd478c81ff 100644 > --- a/fs/gfs2/aops.c > +++ b/fs/gfs2/aops.c > @@ -600,7 +600,7 @@ static void gfs2_readahead(struct readahead_control *rac) > struct gfs2_inode *ip = GFS2_I(inode); > struct gfs2_holder gh; > > - gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh); > + gfs2_holder_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_TRY, &gh); > if (gfs2_glock_nq(&gh)) > goto out_uninit; > if (!gfs2_is_stuffed(ip)) Thanks, Andreas
