bitbake: utils: Add ionice option to prunedir

Autobuilder type infrastructure can benefit from deletion of certain files as
background IO due to the way Linux filesystem priority works.

We have problems where build directories as part of oe-selftest being
delete starves the running tasks of IO to the point builds take much
longer to compelte.

Having this option of running the deletion at "idle" helps a lot with
that.

(Bitbake rev: 797354d285f6d624d9adb52bab65823572da0e39)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/utils.py

@@ -677,7 +677,7 @@ def _check_unsafe_delete_path(path):
         return True
     return False
 
-def remove(path, recurse=False):
+def remove(path, recurse=False, ionice=False):
     """Equivalent to rm -f or rm -rf"""
     if not path:
         return
@@ -686,7 +686,10 @@ def remove(path, recurse=False):
             if _check_unsafe_delete_path(path):
                 raise Exception('bb.utils.remove: called with dangerous path "%s" and recurse=True, refusing to delete!' % path)
         # shutil.rmtree(name) would be ideal but its too slow
-        subprocess.check_call(['rm', '-rf'] + glob.glob(path))
+        cmd = []
+        if ionice:
+            cmd = ['ionice', '-c', '3']
+        subprocess.check_call(cmd + ['rm', '-rf'] + glob.glob(path))
         return
     for name in glob.glob(path):
         try:
@@ -695,12 +698,12 @@ def remove(path, recurse=False):
             if exc.errno != errno.ENOENT:
                 raise
 
-def prunedir(topdir):
+def prunedir(topdir, ionice=False):
     # Delete everything reachable from the directory named in 'topdir'.
     # CAUTION:  This is dangerous!
     if _check_unsafe_delete_path(topdir):
         raise Exception('bb.utils.prunedir: called with dangerous path "%s", refusing to delete!' % topdir)
-    remove(topdir, recurse=True)
+    remove(topdir, recurse=True, ionice=ionice)
 
 #
 # Could also use return re.compile("(%s)" % "|".join(map(re.escape, suffixes))).sub(lambda mo: "", var)