Re: [RFC PATCH 0/8] Ext4 encryption support for blocksize < pagesize

[Chandan Rajendra <chandan@linux.vnet.ibm.com>]

On Wednesday, January 17, 2018 7:40:20 AM IST Eric Biggers wrote:
> Hi Chandan,
> 
> On Fri, Jan 12, 2018 at 07:41:21PM +0530, Chandan Rajendra wrote:
> > This patchset implements code to support encryption of Ext4 filesystem
> > instances that have blocksize less than pagesize. The patchset has
> > been tested on both ppc64 and x86_64 machines.
> > 
> > This patchset changes the prototype of the function
> > fscrypt_encrypt_page(). I will make the relevant changes to the rest
> > of the filesystems (e.g. f2fs) and post them in the next version of
> > the patchset.
> > 
> > Chandan Rajendra (8):
> >   ext4: use EXT4_INODE_ENCRYPT flag to detect encrypted bio
> >   fs/buffer.c: make some functions non-static
> >   ext4: decrypt all contiguous blocks in a page
> >   ext4: decrypt all boundary blocks when doing buffered write
> >   ext4: decrypt the block that needs to be partially zeroed
> >   ext4: encrypt blocks whose size is less than page size
> >   ext4: decrypt blocks whose size is less than page size
> >   ext4: enable encryption for blocksize less than page size
> > 
> 
> Thanks for working on this!  We've wanted this for a while (both so that it
> works on PowerPC with a 64K PAGE_SIZE, and so that people can't screw up their
> 1K blocksize filesystems by enabling the 'encrypt' flag), but no one ever got
> around to it.  And it's not easy!
> 
> First, just a few notes that didn't fit into my comments for the individual
> patches.
> 
> Updating fscrypt_zeroout_range() seems to have been missed.  Currently it
> assumes block_size == PAGE_SIZE so it will need to be updated too.
> 
> The file Documentation/filesystems/fscrypt.rst will also need to be updated, at
> least to remove the following sentence: "Currently, only the case where the
> filesystem block size is equal to the system's page size (usually 4096 bytes) is
> supported.".

Thanks a lot for the review comments. I will make sure to take care of them
in the next version of the patchset.

> 
> Also, on future versions of this patchset can you please also Cc
> linux-fscrypt@vger.kernel.org?
> 

Sure, I will do that.

-- 
chandan