xfs_scrub_all: encapsulate all the subprocess code in an object

Move all the xfs_scrub subprocess handling code to an object so that we
can contain all the details in a single place.  This also simplifies the
background state management.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/scrub/xfs_scrub_all.in b/scrub/xfs_scrub_all.in
index 9dd6347fbd9c4f05b0f60df3c34b0ac28514434a..25286f57ccf15b8e09ab32343a706ad14b937db6 100644 (file)
--- a/scrub/xfs_scrub_all.in
+++ b/scrub/xfs_scrub_all.in
@@ -78,15 +78,62 @@ def remove_killfunc(killfuncs, fn):
        except:
                pass
 
-def run_killable(cmd, stdout, killfuncs):
+class scrub_control(object):
+       '''Control object for xfs_scrub.'''
+       def __init__(self):
+               pass
+
+       def start(self):
+               '''Start scrub and wait for it to complete.  Returns -1 if the
+               service was not started, 0 if it succeeded, or 1 if it
+               failed.'''
+               assert False
+
+       def stop(self):
+               '''Stop scrub.'''
+               assert False
+
+class scrub_subprocess(scrub_control):
+       '''Control object for xfs_scrub subprocesses.'''
+       def __init__(self, mnt, scrub_media):
+               cmd = ['@sbindir@/xfs_scrub']
+               if 'SERVICE_MODE' in os.environ:
+                       cmd += '@scrub_service_args@'.split()
+               cmd += '@scrub_args@'.split()
+               if scrub_media:
+                       cmd += '-x'
+               cmd += [mnt]
+               self.cmdline = cmd
+               self.proc = None
+
+       def start(self):
+               '''Start xfs_scrub and wait for it to complete.  Returns -1 if
+               the service was not started, 0 if it succeeded, or 1 if it
+               failed.'''
+               try:
+                       self.proc = subprocess.Popen(self.cmdline)
+                       self.proc.wait()
+               except:
+                       return -1
+
+               proc = self.proc
+               self.proc = None
+               return proc.returncode
+
+       def stop(self):
+               '''Stop xfs_scrub.'''
+               if self.proc is not None:
+                       self.proc.terminate()
+
+def run_subprocess(mnt, scrub_media, killfuncs):
        '''Run a killable program.  Returns program retcode or -1 if we can't
        start it.'''
        try:
-               proc = subprocess.Popen(cmd, stdout = stdout)
-               killfuncs.add(proc.terminate)
-               proc.wait()
-               remove_killfunc(killfuncs, proc.terminate)
-               return proc.returncode
+               p = scrub_subprocess(mnt, scrub_media)
+               killfuncs.add(p.stop)
+               ret = p.start()
+               remove_killfunc(killfuncs, p.stop)
+               return ret
        except:
                return -1
 
@@ -190,14 +237,7 @@ def run_scrub(mnt, cond, running_devs, mntdevs, killfuncs):
                # Invoke xfs_scrub manually if we're running in the foreground.
                # We also permit this if we're running as a cronjob where
                # systemd services are unavailable.
-               cmd = ['@sbindir@/xfs_scrub']
-               if 'SERVICE_MODE' in os.environ:
-                       cmd += '@scrub_service_args@'.split()
-               cmd += '@scrub_args@'.split()
-               if scrub_media:
-                       cmd += '-x'
-               cmd += [mnt]
-               ret = run_killable(cmd, None, killfuncs)
+               ret = run_subprocess(mnt, scrub_media, killfuncs)
                if ret >= 0:
                        print("Scrubbing %s done, (err=%d)" % (mnt, ret))
                        sys.stdout.flush()