linux-ext4 - Re: [PATCH 1/2] ext4: Fix BUG_ON in ext4_da_block

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Message-ID: <20110316211133.GE4456@quack.suse.cz>
Date:	Wed, 16 Mar 2011 22:11:33 +0100
From:	Jan Kara <jack@...e.cz>
To:	Curt Wohlgemuth <curtw@...gle.com>
Cc:	Jan Kara <jack@...e.cz>, tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/2] ext4: Fix BUG_ON in ext4_da_block_invalidatepages()

  Hi Curt,

On Wed 16-03-11 14:02:02, Curt Wohlgemuth wrote:
> This problem was fixed by the patch I sent on 18 Feb, titled
> 
>    [PATCH 1/2] ext4: mark multi-page IO complete on mapping failure
> 
> I guess this didn't make it into 2.6.38, but it's in the ext4 patch queue now.
  Ah, OK. And I see you also fixed the second issue although my patch IMHO
still makes sense as a cleanup...

								Honza

> On Wed, Mar 16, 2011 at 1:52 PM, Jan Kara <jack@...e.cz> wrote:
> > When an allocation of blocks fails in mpage_da_map_and_submit() e.g. because of
> > EIO we call ext4_da_block_invalidatepages() to invalidate pages we cannot write
> > but we fail to set mpd->io_done. Thus we continue searching for dirty pages and
> > add them to the current extent in mpd structure. Eventually we try to allocate
> > blocks for the extent again and strange things start happening. In particular
> > if the allocation fails again, we try to invalidate pages again and that
> > triggers BUG_ON in ext4_da_block_invalidatepages().
> >
> > Fix the issue by setting mpd->io_done after the pages are invalidated.
> >
> > Signed-off-by: Jan Kara <jack@...e.cz>
> > ---
> >  fs/ext4/inode.c |    1 +
> >  1 files changed, 1 insertions(+), 0 deletions(-)
> >
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index 9f7f9e4..337d9ca 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -2314,6 +2314,7 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
> >                /* invalidate all the pages */
> >                ext4_da_block_invalidatepages(mpd, next,
> >                                mpd->b_size >> mpd->inode->i_blkbits);
> > +               mpd->io_done = 1;
> >                return;
> >        }
> >        BUG_ON(blks == 0);
> > --
> > 1.7.1
> >
> > --
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> >
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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