On Wed, Nov 21, 2012 at 05:47:55PM -0800, Darrick J. Wong wrote:
> On Thu, Nov 22, 2012 at 08:47:13AM +1100, NeilBrown wrote:
> > On Wed, 21 Nov 2012 22:33:33 +0100 Jan Kara <jack@xxxxxxx> wrote:
> >
> > > On Wed 21-11-12 13:13:19, Darrick J. Wong wrote:
> > > > On Wed, Nov 21, 2012 at 03:15:43AM +0100, Jan Kara wrote:
> > > > > On Tue 20-11-12 18:00:56, Darrick J. Wong wrote:
> > > > > > ext3 doesn't properly isolate pages from changes during writeback. Since the
> > > > > > recommended fix is to use ext4, for now we'll just print a warning if the user
> > > > > > tries to mount in write mode.
> > > > > >
> > > > > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > > > > > ---
> > > > > > fs/ext3/super.c | 8 ++++++++
> > > > > > 1 file changed, 8 insertions(+)
> > > > > >
> > > > > >
> > > > > > diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> > > > > > index 5366393..5b3725d 100644
> > > > > > --- a/fs/ext3/super.c
> > > > > > +++ b/fs/ext3/super.c
> > > > > > @@ -1325,6 +1325,14 @@ static int ext3_setup_super(struct super_block *sb, struct ext3_super_block *es,
> > > > > > "forcing read-only mode");
> > > > > > res = MS_RDONLY;
> > > > > > }
> > > > > > + if (!read_only &&
> > > > > > + queue_requires_stable_pages(bdev_get_queue(sb->s_bdev))) {
> > > > > > + ext3_msg(sb, KERN_ERR,
> > > > > > + "error: ext3 cannot safely write data to a disk "
> > > > > > + "requiring stable pages writes; forcing read-only "
> > > > > > + "mode. Upgrading to ext4 is recommended.");
> > > > > > + res = MS_RDONLY;
> > > > > > + }
> > > > > > if (read_only)
> > > > > > return res;
> > > > > > if (!(sbi->s_mount_state & EXT3_VALID_FS))
> > > > > Why this? ext3 should be fixed by your change to
> > > > > filemap_page_mkwrite()... Or does testing show otherwise?
> > > >
> > > > Yes, it's still broken even with this new set of changes. Now that I think
> > > > about it a little more, I recall that writeback mode was actually fine, so this
> > > > is a little harsh.
> > > >
> > > > Hm... looking at the ordered code a little more, it looks like
> > > > ext3_ordered_write_end is calling journal_dirty_data_fn, which (I guess?) tries
> > > > to write mapped buffers back through the journal? Taking it out seems to fix
> > > > ordered mode, though I have a suspicion that it might very well break ordered
> > > > mode too.
> > > Oh, right. kjournald writing buffers directly (without setting
> > > PageWriteback) will break things. So please, change warning to:
>
> Maybe we should just fix this anyway?
>
> I still have the patch that adds PG_stable (and changes the
Page flags are in short supply. If you need a page flag to fix a bug
in a single filesytem, there's a couple of reserved private page
flags that can be used. i.e PG_owner_priv_1. I don't think using a
glbal page flag for just this purpose will fly, though...
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
