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

[Andrea Parri <parri.andrea@gmail.com>]

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.

Thanks!
  Andrea