[Ocfs2-devel] [PATCH] Treat writes as new when holes span across page boundaries

[Joel Becker <jlbec@evilplan.org>]

On Wed, Feb 23, 2011 at 04:31:25PM -0600, Goldwyn Rodrigues wrote:
> Here is a simple script. I will incorporate later into tailtest later.
> 
> FILENAME=/mnt/f2
> 
> for i in `seq 0 256`; do
> 	let s=$i*4096
> 	echo "a" | dd of=$FILENAME count=1 bs=1 seek=$s conv=notrunc 2>/dev/null
> 	let t=$s+4095
> 	echo "b" | dd of=$FILENAME count=1 bs=1 seek=$t conv=notrunc 2>/dev/null
> done

	You shouldn't need to do 256 runs.  I would like to see directed
tests that just hit one spot in a file and expose the corruption.  For
example, your described problem case should work like so:

  # Write the first three blocks of the file, getting us past inline_data
  dd if=/dev/urandom of=$FILENAME count=3 bs=4096
  # Write a byte in the next page
  dd if=/dev/urandom of=$FILENAME count=1 bs=1 seek=12228 conv=notrunc
  # Write after some partial-block portion, trying to expose failed zeroing
  dd if=/dev/urandom of=$FILENAME count=4084 bs=1 seek=12300 conv=notrunc

I would expect this to expose the problem as you've described for
clustersize >= 8K.

Joel

-- 

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