Re: [PATCH 1/1] Null Pointer when make_indexed_dir returns -ENOSPC

[Jan Kara <jack@suse.cz>]

On Mon 09-05-11 19:18:37, Yongqiang Yang wrote:
> On Mon, May 9, 2011 at 7:03 PM, Jan Kara <jack@suse.cz> wrote:
> > On Sat 07-05-11 16:54:27, Allison Henderson wrote:
> >> Fix for a null pointer bug found while running punch hole tests
> >>
> >> Signed-off-by: Allison Henderson <achender@us.ibm.com>
> >> ---
> >> :100644 100644 3c7a06e... 3302a6c... M        fs/ext4/namei.c
> >>  fs/ext4/namei.c |    3 ++-
> >>  1 files changed, 2 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> >> index 3c7a06e..3302a6c 100644
> >> --- a/fs/ext4/namei.c
> >> +++ b/fs/ext4/namei.c
> >> @@ -1422,7 +1422,8 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
> >>                */
> >>               ext4_mark_inode_dirty(handle, dir);
> >>               ext4_handle_dirty_metadata(handle, dir, frame->bh);
> >> -             ext4_handle_dirty_metadata(handle, dir, bh);
> >> +             if (bh)
> >> +                     ext4_handle_dirty_metadata(handle, dir, bh);
> >  I'm puzzled - bh here is bh2 from the beginning of the function and we
> > check it for being NULL after we ext4_append() it. So how can this happen?
> do_split() encounters a journal error and set bh to NULL before returning.
Ah, I see. But then you just reintroduced the bug I was trying to fix. So
either do_split() has to do the marking of buffer dirty, or we have to do
it before calllig do_split(), or do_split() has to be changed and not
release passed buffer (and the two callers have to do it - which they seem
to do anyway). I don't mind either way but your fix is wrong.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR
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