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wic: use truncate utility to create sparse files

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Used truncate instead of dd to create wic images for the
following reasons:
 - dd doesn't preserve sparseness
 - truncate syntax is much more clear
 - dd requires additional calculations of the image size
   in blocks
 - the way dd was used in the code is not always correct.
   In some cases it was writing one block to the file which makes
   it not 100% sparse.

[YOCTO #9099]

(From OE-Core rev: d2d0d18dfd3922411d856b98ab6ba5d64c9c1c9f)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Ed Bartosh
2016-04-28 13:58:04 +03:00
committed by Richard Purdie
parent e93254b482
commit d03cbac796
2 changed files with 8 additions and 24 deletions
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20
scripts/lib/wic/partition.py
View File

@@ -220,9 +220,7 @@ class Partition(object):
msger.debug("Added %d extra blocks to %s to get to %d total blocks" % \
(extra_blocks, self.mountpoint, rootfs_size))
dd_cmd = "dd if=/dev/zero of=%s bs=1024 seek=%d count=0 bs=1k" % \
(rootfs, rootfs_size)
exec_cmd(dd_cmd)
exec_cmd("truncate %s -s %d" % (rootfs, rootfs_size * 1024))
extra_imagecmd = "-i 8192"
@@ -255,9 +253,7 @@ class Partition(object):
msger.debug("Added %d extra blocks to %s to get to %d total blocks" % \
(extra_blocks, self.mountpoint, rootfs_size))
dd_cmd = "dd if=/dev/zero of=%s bs=1024 seek=%d count=0 bs=1k" % \
(rootfs, rootfs_size)
exec_cmd(dd_cmd)
exec_cmd("truncate %s -s %d" % (rootfs, rootfs_size * 1024))
label_str = ""
if self.label:
@@ -320,9 +316,7 @@ class Partition(object):
"""
Prepare an empty ext2/3/4 partition.
"""
dd_cmd = "dd if=/dev/zero of=%s bs=1k seek=%d count=0" % \
(rootfs, self.size)
exec_cmd(dd_cmd)
exec_cmd("truncate %s -s %d" % (rootfs, self.size * 1024))
extra_imagecmd = "-i 8192"
@@ -339,9 +333,7 @@ class Partition(object):
"""
Prepare an empty btrfs partition.
"""
dd_cmd = "dd if=/dev/zero of=%s bs=1k seek=%d count=0" % \
(rootfs, self.size)
exec_cmd(dd_cmd)
exec_cmd("truncate %s -s %d" % (rootfs, self.size * 1024))
label_str = ""
if self.label:
@@ -402,9 +394,7 @@ class Partition(object):
"""
path = "%s/fs.%s" % (cr_workdir, self.fstype)
dd_cmd = "dd if=/dev/zero of=%s bs=1k seek=%d count=0" % \
(path, self.size)
exec_cmd(dd_cmd)
exec_cmd("truncate %s -s %d" % (path, self.size * 1024))
import uuid
label_str = ""

12
scripts/lib/wic/utils/fs_related.py
View File

@@ -71,14 +71,8 @@ class DiskImage(Disk):
def create(self):
if self.device is not None:
return
blocks = self.size / 1024
if self.size - blocks * 1024:
blocks += 1
# create disk image
dd_cmd = "dd if=/dev/zero of=%s bs=1024 seek=%d count=1" % \
(self.image_file, blocks)
exec_cmd(dd_cmd)
# create sparse disk image
cmd = "truncate %s -s %s" % (self.image_file, self.size)
exec_cmd(cmd)
self.device = self.image_file