[PATCH] jffs2: Do not assume erase will fail

[David Woodhouse]

On Mon, 2010-10-25 at 08:49 +0200, Joakim Tjernlund wrote:
> David Woodhouse <dwmw2 at infradead.org> wrote on 2010/10/25 02:11:25:
> >
> > On Thu, 2010-10-07 at 18:29 +0200, Joakim Tjernlund wrote:
> > >
> > > Test if it did and then abort.
> > >
> > > Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund at transmode.se>
> > > ---
> > >  fs/jffs2/nodemgmt.c |    6 +++---
> > >  1 files changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
> > > index 694aa5b..49ee5de 100644
> > > --- a/fs/jffs2/nodemgmt.c
> > > +++ b/fs/jffs2/nodemgmt.c
> > > @@ -260,9 +260,9 @@ static int jffs2_find_nextblock(struct jffs2_sb_info *c)
> > >                 spin_lock(&c->erase_completion_lock);
> > >
> > >                 /* An erase may have failed, decreasing the
> > > -                  amount of free space available. So we must
> > > -                  restart from the beginning */
> > > -               return -EAGAIN;
> > > +                  amount of free space available. */
> > > +               if (list_empty(&c->free_list))
> > > +                       return -EAGAIN; /* restart from the beginning */
> >
> > Hm, but there could have been more than one erase pending (or in
> > progress). And if one fails and another succeeds then you could have a
> > non-empty free_list but you could *also* now have run short of
> > free/freeable space so that a userspace write should now receive
> > -ENOSPC.
> 
> I don't see how my patch changes that, if !list_empty(&c->free_list)
> then you have at least one free block so you should not run into -ENOSPC

Not for jffs2_reserve_space_gc(), you're right. But for non-GC
allocations it's different -- jffs2_reserve_space() will only allow an
allocation if you have more than a certain amount of freeable space,
according to the type of operation. And that amount of freeable space
can be reduced if an erase fails.

-- 
dwmw2