From: Bernhard Voelker <mail@bernhard-voelker.de>
Date: Tue, 16 Sep 2014 16:50:29 +0000 (+0200)
Subject: tests: fix false du failure on newer XFS
X-Git-Tag: v8.24~224
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed0c3c33c6f7c28e5f05e96e1891251bdd181651;p=thirdparty%2Fcoreutils.git

tests: fix false du failure on newer XFS

On XFS, when creating the ~2G test file 'big' in a for-loop by
appending 20M each time, the file ends up using ~4G - visible in
'st_blocks'.  The unused space would be reclaimed later.
This feature is called "speculative preallocation" which aims at
avoiding fragmentation.
According to the XFS FAQ [1], there are two particular aspects of
XFS speculative preallocation that are triggering this:

  1. "Applications that repeatedly trigger preallocation and reclaim
     cycles [after file close] can cause fragmentation.
     Therefore, this pattern is detected and causes the preallocation
     to persist beyond the lifecycle of the file descriptor."

  2. "Preallocation sizes grow as files grow larger."

[1] http://xfs.org/index.php/XFS_FAQ

Avoid one of the above by only doing a single close (reclaim cycle).

* tests/du/2g.sh: Similar to the fix for a dd test (see commit
v8.22-65-g7c03fe2), avoid speculative preallocation by creating
the 'big' file in one go instead of appending to it in the loop.
Remove debugging statements as the output with 'set -x' is
sufficient nowadays.
---

diff --git a/tests/du/2g.sh b/tests/du/2g.sh
index f766d4d9dd..d7cc987d0d 100755
--- a/tests/du/2g.sh
+++ b/tests/du/2g.sh
@@ -43,15 +43,14 @@ test $min_kb -lt $free_kb ||
 
 big=big
 rm -f $big
-test -t 1 || printf 'creating a 2GB file...\n'
-for i in $(seq 100); do
-  # Note: 2147483648 == 2^31. Print floor(2^31/100) per iteration.
-  printf %21474836s x >> $big || fail=1
-  # On the final iteration, append the remaining 48 bytes.
-  test $i = 100 && { printf %48s x >> $big || fail=1; }
-  test -t 1 && printf 'creating a 2GB file: %d%% complete\r' $i
-done
-echo
+{
+  for i in $(seq 100); do
+    # Note: 2147483648 == 2^31. Print floor(2^31/100) per iteration.
+    printf %21474836s x || fail=1
+  done
+  # After the final iteration, append the remaining 48 bytes.
+  printf %48s x || fail=1
+} > $big || fail=1
 
 du -k $big > out1 || fail=1
 rm -f $big