On Wed, Apr 03, 2013 at 04:41:01PM +0200, Lukáš Czerner wrote:
> Hi Ted,
>
> there is a problem with your patch:
>
> 32d90a241a44d22ebc5289d2a2561691fc2d1351
>
> because there is one more case where we might call ext4_truncate()
> without i_mutex locked - from ext4_symlink(). Because we might be
> calling __page_symlink() and it will call ext4_write_begin(). In
> possible error case (ENOSPC for example) we might want to truncate
> everything which might have been instantiated past i_size, however
> at that point we're not holding i_mutex because there is no point in
> doing so - the inode can not be possibly held by anyone else.
>
> My proposal is to only check whether the mutex is locked if the
> inode is _not_ new or is _not_ being freed.
>
> There is a quick&dirty patch and it seems to be working well so
> far. Let me know if you prefer standalone patch, or if you'll
> include it into your commit.
I really like your approach. We've been trying a number of other
approaches, including
http://patchwork.ozlabs.org/patch/232914/
and
http://patchwork.ozlabs.org/patch/231679/
but I think your suggestion is the best.
Thanks!!
- Ted
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