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Make sure loop device is setup (#1462150) 

It seems that on rare occasions losetup can return before the /dev/loopX
is ready for use, causing problems with mkfs. This tries to make sure
that the loop device really is associated with the backing file before
continuing.

Resolves: rhbz#1462150
This commit is contained in:
Brian C. Lane 2017-06-21 14:31:35 -07:00
parent db32eb7295
commit e0d9e309ae
1 changed files with 22 additions and 0 deletions
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22
src/pylorax/imgutils.py
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@ -125,10 +125,32 @@ def mkqcow2(outfile, size, options=None):
options.extend(["-f", "qcow2"])
runcmd(["qemu-img", "create"] + options + [outfile, str(size)])
def loop_waitfor(loop_dev, outfile):
"""Make sure the loop device is attached to the outfile.
It seems that on rare occasions losetup can return before the /dev/loopX is
ready for use, causing problems with mkfs. This tries to make sure that the
loop device really is associated with the backing file before continuing.
Raise RuntimeError if it isn't setup after 5 tries.
"""
for x in xrange(0,5):
runcmd(["udevadm", "settle", "--timeout", "300"])
buf = runcmd_output(["losetup", "--list", "-O", "BACK-FILE", loop_dev])
lines = buf.splitlines()
if len(lines) < 2:
continue
if lines[1].strip() == outfile:
return
raise RuntimeError("Unable to setup %s on %s" % (loop_dev, outfile))
def loop_attach(outfile):
'''Attach a loop device to the given file. Return the loop device name.
Raises CalledProcessError if losetup fails.'''
dev = runcmd_output(["losetup", "--find", "--show", outfile])
# Sometimes the loop device isn't ready yet, make extra sure before returning
loop_waitfor(dev, outfile)
return dev.strip()
def loop_detach(loopdev):