Theodore Tso wrote:
quoted text
> On Fri, May 15, 2009 at 06:32:45AM +0930, Kevin Shanahan wrote:
>> Okay, so now I've booted into 2.6.29.3 + check_block_validity patch +
>> short circuit i_cached_extent patch, mounted the fs without
>> nodelalloc. I was able to run the full exchange backup without
>> triggering the check_block_validity error.
> 
> Great!
> 
> So here's the final fix (it replaces the short circuit i_cached_extent
> patch) which I plan to push to Linus.  It should be much less of a
> performance hit than simply short-circuiting i_cached_extent...
> 
> Thanks so much for helping to find track this down!!!  If ever someone
> deserved an "Ext4 Baker Street Irregulars" T-shirt, it would be
> you....
> 
>        	       	   	      	   	      - Ted

So here's a fio job I thought would try to hit this ...

[global]
ioengine=libaio
iodepth=1
filesize=4g
bs=1m
norandommap
direct=1
loops=500
size=16g

[setup]
filename=file
rw=randwrite
loops=1

[thread1]
stonewall
filename=file
rw=randwrite

[thread2]
filename=file
rw=randread

it should lay out a 4g file in random 1m direct IOs to fragment it and
get a lot of extents, then launch 2 threads, one each doing random reads
and random writes of that same file.

I can't make this trip it, though ...

-Eric
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