I tried to mount a formerly readonly mounted filesystem read-writeable:
mount -o remount,rw /mountpoint
Unfortunately it did not work:
mount: /mountpoint not mounted already, or bad option
[2570543.520449] EXT4-fs (dm-0): Couldn't remount RDWR because of unprocessed orphan inode list. Please umount/remount instead
umount does not work, too:
umount /mountpoint umount: /mountpoint: device is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1))
fuser don’t show any process accessing something located under the mount point.
So – how can I clean up this unprocessed orphan list to be able to mount the filesystem again without rebooting the computer?
You clean up the unprocessed orphan inode list by unmounting and remounting the filesystem.
An extended discussion from the linux-ext4 mailing list has more information about what this message is and why it may appear. In short, one of two things has happened: Either you’ve run into a kernel bug, or much more likely, some filesystem corruption happened one of the previous times you remounted the filesystem readonly. Which is probably why the system thinks something is still using the filesystem when there isn’t.
If it’s been a year and you still haven’t rebooted the machine, just give up and schedule a maintenance window.
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