Re: [PATCH v2] xfs: exercise a failed CoW conversion during writeback

[Zorro Lang <zlang@kernel.org>]

On Mon, Sep 28, 2026 at 06:24:42PM +0200, Andrea Parri wrote:
> On Mon, Sep 28, 2026 at 08:41:49AM -0700, Darrick J. Wong wrote:
> > for ((off = 0; off < (blksz * nr * 2); off += (blksz * 2))); do
> > 	_pwrite_byte 0x59 $off $blksz $SCRATCH_MNT/file2 >> $seqres.full
> > done
> 
> That's nicer, no loop counter at all, and it writes the same eight
> ranges as before.
> 
> Zorro, if you're folding the fix in at merge time, please use Darrick's
> version rather than the rename I suggested earlier, i.e.:
> 
> @@ -48,11 +48,8 @@ _cp_reflink $SCRATCH_MNT/file1 $SCRATCH_MNT/file2
>  
>  # Dirty several widely separated ranges of file2's CoW extents so that a
>  # single writepages() call has to submit more than one ioend.
> -seq=0
> -while [ $seq -lt $nr ]; do
> -	off=$((seq * blksz * 2))
> +for ((off = 0; off < (blksz * nr * 2); off += (blksz * 2))); do
>  	_pwrite_byte 0x59 $off $blksz $SCRATCH_MNT/file2 >> $seqres.full
> -	seq=$((seq + 1))
>  done
>  
>  echo "Inject wb_cow_convert_error"
> 
> Again, happy to send a v3 with this if that's easier.

I've merged it with above changes, feel free to check *patches-in-queue* branch.

Thanks,
Zorro

> 
> Thanks!
>   Andrea