sd_fusing.py: Invoke ioctl to reread partitions directly

This commit drops blockdev(8) in favor for invoking ioctl(2) directly,
to be able to catch EBUSY errors that happen to occur due to not yet
known kernel/udev timinig issue.

This commit also drops sfdisk --no-reread flag, which affects issuing
ioctl to reread partition table _before_ actual repartitioning.  ioctl
to reread partition table after writing changes is invoked unconditionally
and can't be disabled.

Change-Id: I105c445f9fdb3d1d2eee7ffd2de3f7ad04920f13
Signed-off-by: Karol Lewandowski <k.lewandowsk@samsung.com>

diff --git a/scripts/tizen/sd_fusing.py b/scripts/tizen/sd_fusing.py
index a564c2f..8aafc8a 100755 (executable)
--- a/scripts/tizen/sd_fusing.py
+++ b/scripts/tizen/sd_fusing.py
@@ -5,6 +5,7 @@ from functools import reduce
 import argparse
 import atexit
 import errno
+import fcntl
 import logging
 import os
 import re
@@ -14,6 +15,7 @@ import subprocess
 import sys
 import tarfile
 import tempfile
+import time
 
 __version__ = "1.0.4"
 
@@ -24,6 +26,7 @@ Yes = False
 SuperDelivered = False
 
 LOGGING_NOTICE = int((logging.INFO + logging.WARNING) / 2)
+BLKRRPART = 4703 # from linux/fs.h
 
 class DebugFormatter(logging.Formatter):
     def format(self, record):
@@ -780,7 +783,7 @@ def mkpart(args, target):
             sys.exit(1)
 
     logging.debug("New partition table:\n" + str(target.label))
-    argv = ['sfdisk', '--no-reread', '--wipe-partitions', 'always', Device]
+    argv = ['sfdisk', '--wipe-partitions', 'always', Device]
     logging.debug(" ".join(argv))
     proc = subprocess.run(argv,
                           stdout=None,
@@ -791,15 +794,29 @@ def mkpart(args, target):
         logging.error(f"New partition table:\n" + str(target.label))
         sys.exit(1)
 
+    # Invoke ioctl directly as blockdev sometimes fails with EBUSY for no known reason (udev/kernel timing issue?)
+    wait_secs = 3
     logging.debug("Requesting kernel to re-read partition table:\n" + str(target.label))
-    argv = ['blockdev', '--rereadpt', Device]
-    logging.debug(" ".join(argv))
-    proc = subprocess.run(argv,
-                          stdout=None,
-                          stderr=None)
-    if proc.returncode != 0:
-        logging.error(f"Failed to request kernel to reread partition table on {Device}. (Insufficient permissions?)")
+    rereadpt_ok = False
+    rereadpt_err = f"Failed to request kernel to re-read partition table on {Device}"
+    for i in range(5):
+        try:
+            with open(Device, "wb") as f:
+                fcntl.ioctl(f.fileno(), BLKRRPART)
+                rereadpt_ok = True
+                break
+        except OSError as e:
+            if e.errno == errno.EBUSY:
+                logging.error(f"{rereadpt_err}: {e.strerror}. Retrying after {wait_secs} seconds")
+                time.sleep(wait_secs)
+            else:
+                logging.error(f"{rereadpt_err}: {e.strerror}")
+                sys.exit(1)
+    if not rereadpt_ok:
+        logging.error(f"{rereadpt_err}")
         sys.exit(1)
+    else:
+        logging.notice(f"Successfully re-read partition table on {Device}")
 
     if target.bootcode:
         logging.debug("Writing bootcode\n")