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    SubjectRe: partially encrypted filesystem
    Hi!

    > > Of course, all this is at the logical file level, and ignores the
    > > physical blocks on disk. All filesystems assume physical data blocks
    > > can be updated in place. With compression it is possible a new physical
    > > block has to be found, especially if blocks are highly packed and not
    > > aligned to block boundaries. I expect this is at least partially why
    > > JFFS2 is a log structured filesystem.
    >
    > Not really. JFFS2 is a log structured file system because it's designed
    > to work on _flash_, not on block devices. You have an eraseblock size of
    > typically 64KiB, you can clear bits in that 'block' all you like till
    > they're all gone or you're bored, then you have to erase it back to all
    > 0xFF again and start over.
    >
    > Even if you were going to admit to having a block size of 64KiB to the
    > layers above you, you just can't _do_ atomic replacement of blocks,
    > which is required for normal file systems to operate correctly.

    Are those assumptions needed for something else than recovery after
    crash/powerdown? [i.e., afaics 64K ext2 should work on flash, but fsck
    might have some troubles...]

    Pavel
    --
    When do you have a heart between your knees?
    [Johanka's followup: and *two* hearts?]
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