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devices/loopback: option to lock the device

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Implement a new `lock` option (default: False), which will lock
the device by passing `lock=True` to `LoopControl.loop_for_fd`.
The main purpose for this is to block udev from probing the device
while the stage is run.
NB: some tools might also try to lock the device and fail.
This commit is contained in:
Christian Kellner 2021-08-09 14:01:57 +00:00 • committed by Tom Gundersen
parent c1379f63ab
commit bd0e5f19fd
1 changed files with 8 additions and 3 deletions
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11
devices/org.osbuild.loopback
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@ -46,6 +46,10 @@ SCHEMA = """
"type": "number",
"description": "Sector size (in bytes)",
"default": 512
},
"lock": {
"type": "boolean",
"description": "Lock the device after opening it"
}
}
"""
@ -59,14 +63,14 @@ class LoopbackService(devices.DeviceService):
self.lo = None
self.ctl = loop.LoopControl()
def make_loop(self, fd: int, offset, sizelimit):
def make_loop(self, fd: int, offset, sizelimit, lock):
if not sizelimit:
stat = os.fstat(fd)
sizelimit = stat.st_size - offset
else:
sizelimit *= self.sector_size
lo = self.ctl.loop_for_fd(fd,
lo = self.ctl.loop_for_fd(fd, lock=lock,
offset=offset,
sizelimit=sizelimit,
partscan=False,
@ -79,13 +83,14 @@ class LoopbackService(devices.DeviceService):
self.sector_size = options.get("sector-size", 512)
start = options.get("start", 0) * self.sector_size
size = options.get("size")
lock = options.get("lock", False)
path = os.path.join(tree, filename.lstrip("/"))
self.fd = os.open(path, os.O_RDWR | os.O_CLOEXEC)
print(f"file '{filename}'' opened as {self.fd}")
try:
self.lo = self.make_loop(self.fd, start, size)
self.lo = self.make_loop(self.fd, start, size, lock)
except Exception as error: # pylint: disable: broad-except
self.close()
raise error from None