On 23/08/2025 01:48, Paul Eggert wrote:
On 8/22/25 07:04, Pádraig Brady wrote:
/* Copy this extent, looking for further opportunities to not
bother to write zeros if --sparse=always, since SEEK_HOLE
is conservative and may miss some holes. */
So the comment needs to be tweaked, but a more general issue
is that it disables copy offloading (copy_file_range) for sparse files.
Ouch, I didn't see that. That's a real loss. I installed the first
attached patch to revert that part of my recent change.
Cool. I'll push the attached test to enforce this
I assume the part of the change that always punches holes is OK. I
couldn't see why one would not want to punch a hole if one has already
taken the trouble to find and create the hole.
Fair enough. It simplifies the code anyway.
BTW commit 26bf557 also changed this a couple of weeks ago
without updating the comment, so the comment relates to sparse_mode !=
SPARSE_ALWAYS.
Not quite following but I hope the comment is OK now with the first
patch installed.
Right, I missed that commit 26bf557 didn't actually change the logic
for this line, only the syntax.
thanks!
Padraig
From 6c668dc133af7d374790c1da666a701e21682a35 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A1draig=20Brady?= <p...@draigbrady.com>
Date: Sat, 23 Aug 2025 18:53:17 +0100
Subject: [PATCH] tests: cp: ensure copy offload is not disabled for sparse
files
Related to commits v9.1-109-g879d2180d and v9.7-248-g306de6c26
* tests/cp/sparse-perf.sh: This edge case was missed a couple of times,
so add a test to ensure we attempt copy offload.
---
tests/cp/sparse-perf.sh | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/tests/cp/sparse-perf.sh b/tests/cp/sparse-perf.sh
index 8f737f798..5a283c1fe 100755
--- a/tests/cp/sparse-perf.sh
+++ b/tests/cp/sparse-perf.sh
@@ -18,8 +18,27 @@
. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
print_ver_ cp
+cleanup_() { rm -rf "$other_partition_tmpdir"; }
+. "$abs_srcdir/tests/other-fs-tmpdir"
+
+# Create a sparse file on another partition to avoid reflinking
+# thus exercising more copy logic
+
+other_partition_sparse=$other_partition_tmpdir/k
+printf x > $other_partition_sparse || framework_failure_
+truncate -s1M $other_partition_sparse || framework_failure_
+
+# cp should not disable anything by default, even for sparse files. For e.g.
+# copy offload is an important performance improvement for sparse files on NFS.
+cp --debug $other_partition_sparse k2 >cp.out || fail=1
+cmp $other_partition_sparse k2 || fail=1
+grep ': avoided' cp.out && { cat cp.out; fail=1; }
+
+
+
+# Create a large-but-sparse file on the current partition.
+# We disable relinking below, thus verifying SEEK_HOLE support
-# Create a large-but-sparse file.
timeout 10 truncate -s1T f ||
skip_ "unable to create a 1 TiB sparse file"
--
2.50.1
