Hello Hamish,
> Good idea, but sadly that just shows the default mount options.
Then that suggests they haven't been changed, at least if that old
kernel matches mine here.
Make an ext4 filesystem and mount point.
$ dd if=/dev/zero bs=2M count=1 of=fs.img
1+0 records in
1+0 records out
2097152 bytes (2.1 MB, 2.0 MiB) copied, 0.0164876 s, 127 MB/s
$ mkfs -t ext4 fs.img
mke2fs 1.45.2 (27-May-2019)
Discarding device blocks: done
Creating filesystem with 2048 1k blocks and 256 inodes
Allocating group tables: done
Writing inode tables: done
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done
$ mkdir mnt
$
Mount it with duff options.
$ sudo mount -o loop,data=writeback,barrier=0,commit=30 fs.img mnt
$ fgrep $PWD /proc/$$/mountinfo
753 193 7:1 / /home/tmp/1598690175.392785701/mnt rw,relatime shared:408 -
ext4 /dev/loop1 rw,nobarrier,commit=30,data=writeback
$
Attempt to change all of them to sane ones.
$ sudo mount -o loop,remount,data=ordered,barrier=1,commit=5 fs.img mnt
mount: /home/tmp/1598690175.392785701/mnt: mount point not mounted or bad
option.
$ fgrep $PWD /proc/$$/mountinfo
753 193 7:1 / /home/tmp/1598690175.392785701/mnt rw,relatime shared:408 -
ext4 /dev/loop1 rw,nobarrier,commit=30,data=writeback
$
None of them change. It's because it's not possible to change ‘data’
with remount.
Change the other two options.
$ sudo mount -o loop,remount,barrier=1,commit=5 fs.img mnt
$ fgrep $PWD /proc/$$/mountinfo
753 193 7:1 / /home/tmp/1598690175.392785701/mnt rw,relatime shared:408 -
ext4 /dev/loop1 rw,data=writeback
$
Try again to change the remaining one.
$ sudo mount -o loop,remount,data=ordered fs.img mnt
mount: /home/tmp/1598690175.392785701/mnt: mount point not mounted or bad
option.
$ fgrep $PWD /proc/$$/mountinfo
753 193 7:1 / /home/tmp/1598690175.392785701/mnt rw,relatime shared:408 -
ext4 /dev/loop1 rw,data=writeback
$
Still doesn't work.
$ sudo umount mnt
$
So if...
> Good idea, but sadly that just shows the default mount options.
...then it suggests none of your remount-option changes have taken
effect?
--
Cheers, Ralph.
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