ext2.ko itself does support fsfreeze, but typical linux distros, like Ubuntu, don't supply ext2.ko at all now -- instead, they usually supply ext3.ko and have ext4 built-in.
So when we mount an ext2 partition, actually the kernel is registering the ext4 driver as an ext2 driver and in this case the ext2's s_op->freeze_fs is NULL -- so fsfreeze on ext3 can get -EOPNOTSUPP.
ext2.ko itself does support fsfreeze, but typical linux distros, like Ubuntu, don't supply ext2.ko at all now -- instead, they usually supply ext3.ko and have ext4 built-in.
So when we mount an ext2 partition, actually the kernel is registering the ext4 driver as an ext2 driver and in this case the ext2's s_op->freeze_fs is NULL -- so fsfreeze on ext3 can get -EOPNOTSUPP.
The discussion is at http:// marc.info/ ?t=141102289600 007&r=1& w=2
The ext4 community has posted the patches to support ext2 fsfreeze when registering ext4 as ext2: marc.info/ ?l=linux- ext4&m= 141107200212887 &w=2 marc.info/ ?l=linux- ext4&m= 141107200312889 &w=2 marc.info/ ?l=linux- ext4&m= 141107481213962 &w=2
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