Re: [PATCH 2/5] reflink: fix off-by-one errors when iterating file blocks in a loop

Filipe Manana
2016-01-23T11:32:28Z

On Sat, Jan 23, 2016 at 12:36 AM, Darrick J. Wong
<darrick.wong@oracle.com> wrote:
> When we're iterating file blocks in a loop (via seq), we have to
> end at $nr-1, not $nr.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> tests/generic/183 | 2 +-
> tests/generic/185 | 2 +-
> tests/generic/186 | 2 +-
> tests/generic/187 | 2 +-
> tests/generic/194 | 2 +-
> tests/generic/195 | 2 +-
> tests/xfs/129 | 6 +++---
> tests/xfs/140 | 2 +-
> 8 files changed, 10 insertions(+), 10 deletions(-)
>
>
> diff --git a/tests/generic/183 b/tests/generic/183
> index 5c65e9a..2cf9ce4 100755
> --- a/tests/generic/183
> +++ b/tests/generic/183
> @@ -69,7 +69,7 @@ seq 0 2 $((NR-1)) | while read f; do
> _reflink_range "$TESTDIR/file1" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x61 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> -seq 1 2 $NR | while read f; do
> +seq 1 2 $((NR-1)) | while read f; do

Just curious (and no bike shedding intended), why not make the loop in
a much more simple and common way such as:

for ((i = 1; i < $NR; i += 2)); do
...
done

or for i in `seq 1 2 $((NR - 1))`; do .... done

> _reflink_range "$TESTDIR/file2" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> diff --git a/tests/generic/185 b/tests/generic/185
> index 384c9aa..55c54ac 100755
> --- a/tests/generic/185
> +++ b/tests/generic/185
> @@ -69,7 +69,7 @@ seq 0 2 $((NR-1)) | while read f; do
> _reflink_range "$TESTDIR/file1" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x61 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> -seq 1 2 $NR | while read f; do
> +seq 1 2 $((NR-1)) | while read f; do
> _reflink_range "$TESTDIR/file2" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> diff --git a/tests/generic/186 b/tests/generic/186
> index d84166d..f1c0e6b 100755
> --- a/tests/generic/186
> +++ b/tests/generic/186
> @@ -112,7 +112,7 @@ seq 0 2 $((NR-1)) | while read f; do
> _reflink_range "$TESTDIR/file1" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x61 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> -seq 1 2 $NR | while read f; do
> +seq 1 2 $((NR-1)) | while read f; do
> _reflink_range "$TESTDIR/file2" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> diff --git a/tests/generic/187 b/tests/generic/187
> index c85a0a9..ce35ec0 100755
> --- a/tests/generic/187
> +++ b/tests/generic/187
> @@ -112,7 +112,7 @@ seq 0 2 $((NR-1)) | while read f; do
> _reflink_range "$TESTDIR/file1" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x61 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> -seq 1 2 $NR | while read f; do
> +seq 1 2 $((NR-1)) | while read f; do
> _reflink_range "$TESTDIR/file2" $((BLKSZ * f)) "$TESTDIR/file3" $((BLKSZ * f)) $BLKSZ >> "$seqres.full"
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> diff --git a/tests/generic/194 b/tests/generic/194
> index a441aee..b88297e 100755
> --- a/tests/generic/194
> +++ b/tests/generic/194
> @@ -79,7 +79,7 @@ md5sum "$TESTDIR/file3" | _filter_scratch
> md5sum "$TESTDIR/file3.chk" | _filter_scratch
>
> echo "directio CoW across the transition"
> -seq 1 2 $NR | while read f; do
> +seq 1 2 $((NR-1)) | while read f; do
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3" >> "$seqres.full"
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> diff --git a/tests/generic/195 b/tests/generic/195
> index 83e7b23..464a4d4 100755
> --- a/tests/generic/195
> +++ b/tests/generic/195
> @@ -79,7 +79,7 @@ md5sum "$TESTDIR/file3" | _filter_scratch
> md5sum "$TESTDIR/file3.chk" | _filter_scratch
>
> echo "CoW across the transition"
> -seq 1 2 $NR | while read f; do
> +seq 1 2 $((NR-1)) | while read f; do
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3" >> "$seqres.full"
> _pwrite_byte 0x62 $((BLKSZ * f)) $BLKSZ "$TESTDIR/file3.chk" >> "$seqres.full"
> done
> diff --git a/tests/xfs/129 b/tests/xfs/129
> index c8c47a2..3b7c59c 100755
> --- a/tests/xfs/129
> +++ b/tests/xfs/129
> @@ -65,9 +65,9 @@ NR_BLKS=$((4 * BLKSZ / 12))
> _pwrite_byte 0x61 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/file1" >> "$seqres.full"
>
> echo "Reflink every other block"
> -seq 1 $((NR_BLKS / 2)) | while read nr; do
> - _reflink_range "$TESTDIR/file1" $((nr * 2 * BLKSZ)) \
> - "$TESTDIR/file2" $((nr * 2 * BLKSZ)) $BLKSZ >> "$seqres.full"
> +seq 1 2 $((NR_BLKS - 1)) | while read nr; do
> + _reflink_range "$TESTDIR/file1" $((nr * BLKSZ)) \
> + "$TESTDIR/file2" $((nr * BLKSZ)) $BLKSZ >> "$seqres.full"
> done
>
> echo "Create metadump file"
> diff --git a/tests/xfs/140 b/tests/xfs/140
> index e20cd3f..45be9f4 100644
> --- a/tests/xfs/140
> +++ b/tests/xfs/140
> @@ -70,7 +70,7 @@ cmp -s "$TESTDIR/file1" "$TESTDIR/file2" || echo "file1 and file2 do not match"
> cmp -s "$TESTDIR/file2" "$TESTDIR/file2.chk" || echo "file2 and file2.chk do not match"
>
> echo "CoW every other block"
> -seq 1 2 $NR | while read f; do
> +seq 1 2 $((NR - 1)) | while read f; do
> _pwrite_byte 0x62 $((f * BLKSZ)) $BLKSZ "$TESTDIR/file2" >> "$seqres.full"
> _pwrite_byte 0x62 $((f * BLKSZ)) $BLKSZ "$TESTDIR/file2.chk" >> "$seqres.full"
> done
>
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--
Filipe David Manana,

"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."