linux-ext4 - Re: [PATCH 1/3] fscrypt: add support for inline-encryption-optimized policies

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Message-ID: <20191022161504.GA229362@gmail.com>
Date:   Tue, 22 Oct 2019 09:15:06 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Dave Chinner <david@...morbit.com>, linux-fscrypt@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, Satya Tangirala <satyat@...gle.com>,
        Paul Crowley <paulcrowley@...gle.com>,
        Paul Lawrence <paullawrence@...gle.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>
Subject: Re: [PATCH 1/3] fscrypt: add support for inline-encryption-optimized
 policies

On Tue, Oct 22, 2019 at 09:30:01AM -0400, Theodore Y. Ts'o wrote:
> > An alternative which would work nicely on ext4 and xfs (if xfs supported
> > fscrypt) would be to pass the physical block number as the DUN.  However, that
> > wouldn't work at all on f2fs because f2fs moves data blocks around.  And since
> > most people who want to use this are using f2fs, f2fs support is essential.
> 
> And that is something fscrypt supports already, so if people really
> did want to use 64-bit logical block numbers, they could do that, at
> the cost of giving up the ability to shrink the file system (which XFS
> doesn't support anyway....)

I was talking about the physical block number (offset from the start of the
filesystem -- ext4_fsblk_t on ext4), not the file logical block number (offset
in the file data -- ext4_lblk_t on ext4).  fscrypt doesn't currently support
using the physical block number.

- Eric