Re: [Patch] btrfs: use file_remove_suid() after i_mutex is held

[Amerigo Wang]

Arjan van de Ven wrote:
> On Mon, 6 Jul 2009 01:29:14 -0400
> Amerigo Wang <amwang@xxxxxxxxxx> wrote:
>
>   
> > file_remove_suid() should be called with i_mutex held,
> > file_update_time() too. So move them after mutex_lock().
> >
> > Plus, check the return value of kmalloc().
> >
> > Signed-off-by: WANG Cong <amwang@xxxxxxxxxx>
> >
> > ---
> > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> > index 7c3cd24..cd36301 100644
> > --- a/fs/btrfs/file.c
> > +++ b/fs/btrfs/file.c
> > @@ -944,14 +944,17 @@ static ssize_t btrfs_file_write(struct file
> > *file, const char __user *buf, if (count == 0)
> >  		goto out_nolock;
> >  
> > +	mutex_lock(&inode->i_mutex);
> > +
> >  	err = file_remove_suid(file);
> >  	if (err)
> > -		goto out_nolock;
> > +		goto out;
> >  	file_update_time(file);
> >  
> >  	pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
> > +	if (!pages)
> > +		goto out;
> >  
> >     
> Hi,
>
> I don't think you can keep this at GFP_KERNEL once you hold i_mutex....
> very likely this needs to now turn into GFP_NOFS!
>   

Good point!
Hmm,  GFP_KERNEL adds __GFP_FS while GFP_NOFS not...
Just moving that kmalloc() up, before mutex_lock(), I think, can solve
this.

I will update this patch now...

Thanks!

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