[PATCH v3 1/2] common: new helper to alloacate fixed size files

[Pavel Reichl <preichl@redhat.com>]

Helper that creates files of specified size using falloc if supported,
otherwise pwrite is used.

Signed-off-by: Pavel Reichl <preichl@redhat.com>
---
 common/rc         | 13 +++++++++++++
 tests/generic/694 |  2 +-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/common/rc b/common/rc
index a25cbcd0..77866582 100644
--- a/common/rc
+++ b/common/rc
@@ -4925,6 +4925,19 @@ hexdump()
 	_fail "Use _hexdump(), please!"
 }
 
+# Helper to write a file containing specified number of bytes using
+# falloc if supported, otherwise use pwrite
+_create_sizedfile()
+{
+	length=$1
+	file=$2
+
+	$XFS_IO_PROG -F -fc "falloc 0 $length" $file 2>&1 | grep -q "Operation not supported"
+	if [ $? -eq 0 ]; then
+		$XFS_IO_PROG -F -fc "pwrite -W 0 $length" $file >/dev/null
+	fi
+}
+
 init_rc
 
 ################################################################################
diff --git a/tests/generic/694 b/tests/generic/694
index dfd988df..64c3dd9a 100755
--- a/tests/generic/694
+++ b/tests/generic/694
@@ -30,7 +30,7 @@ junk_dir=$TEST_DIR/$seq
 junk_file=$junk_dir/junk
 mkdir -p $junk_dir
 
-$XFS_IO_PROG -f -c "pwrite -W 0 4G" $junk_file > /dev/null
+_create_sizedfile 4G $junk_file
 
 iblocks=`stat -c '%b' $junk_file`
 
-- 
2.37.3