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Re: ext3 + loop + journaling

Jani Averbach wrote:
> Is there any way to mix loop-device (and in particular) loop-AES and ext3
> together in data journaling mode?

Device backed loops (ext3 -> loop -> device) don't have issues with ext3 or
any other journaled filesystems.

However, if loop is file backed (ext3 -> loop -> ext3 -> device), the
underlying file system must be mounted data=journal or data=ordered. If
underlying filesystem is mounted data=writeback or if it is plain old ext2,
write ordering expectation by journaled filesystem (ext3, reiserfs, jfs,
xfs, or whatever) on top of loop driver is not guaranteed, and journal
replay may corrupt data. Use of non-journaled file systems on top of file
backed loop don't have above mentioned write ordering issues, as they must
be repaired using fsck, not by replaying journal.

Jari Ruusu <jari ruusu pp inet fi>

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