Re: 2.5.12 severe ext3 filesystem corruption warning!

[Daniel Pittman <daniel@rimspace.net>]

On Thu, 02 May 2002, Andrew Morton wrote:
> Alexander Viro wrote:
>> On Thu, 2 May 2002, Andrew Morton wrote:
>> > A few things..

[...]

>> I suspect that you had screwed the truncate exclusion warranties up. 
>> If _any_ IO happens in the area currently manipulated by ->truncate()
>> - you are screwed and results would look pretty much like the things
>> mentioned in bug report.
> 
> OK, thanks.  That's something to go on.
> 
> The only change which comes to mind is discard_buffer() - it's
> no longer clearing BH_Uptodate.  Because for the partial page
> at the end of the mapping, buffers outside i_size were zeroed
> in truncate_partial_page().  But with (presumed) 4k blocksize,
> it can't be that.
> 
> ext3_writepage() can hold a reference against the buffers
> after the page has come unlocked, so a try_to_free in the
> right window will fail, which will leave the page floating
> about on the page LRU, not mapped into any address_space,
> clean, not uptodate, but with uptodate buffers.  Nobody
> but the VM should ever find that page, but it does make more
> sense to mark that buffer not uptodate.  This would only
> happen on super-heavy SMP loads.

Oh, it's a laptop, so SMP is right out of the picture. ;)
        Daniel

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