image_types: btrfs use sparse file creation

This will speed up file creation and still allow the btrfs tools to
create a full btrfs image.  This is similar to what we do for ext234
FS types.

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
(cherry picked from commit de2f2fc9e8e6d874a11e69adc2f438975a5c1359)
Signed-off-by: Armin Kuster <akuster808@gmail.com>

diff --git a/meta/classes/image_types.bbclass b/meta/classes/image_types.bbclass
index d09d1277eaa21e0106a8df07c84ce1a88ef3ee3a..e881d0cc2d3f45344e7d08f47d29a0a6c6049ed1 100644 (file)
--- a/meta/classes/image_types.bbclass
+++ b/meta/classes/image_types.bbclass
@@ -104,7 +104,7 @@ IMAGE_CMD_btrfs () {
                size=${MIN_BTRFS_SIZE}
                bbwarn "Rootfs size is too small for BTRFS. Filesystem will be extended to ${size}K"
        fi
-       dd if=/dev/zero of=${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.btrfs count=${size} bs=1024
+       dd if=/dev/zero of=${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.btrfs seek=${size} count=0 bs=1024
        mkfs.btrfs ${EXTRA_IMAGECMD} -r ${IMAGE_ROOTFS} ${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.btrfs
 }