linux-kernel - Re: [PATCH 01/26] fscrypto: Add buffer operations

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Date:   Fri, 21 Oct 2016 06:24:00 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Richard Weinberger <richard@....at>
Cc:     Christoph Hellwig <hch@...radead.org>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, dedekind1@...il.com,
        adrian.hunter@...el.com, tytso@....edu, jaegeuk@...nel.org,
        david@...ma-star.at, wd@...x.de, sbabic@...x.de,
        dengler@...utronix.de
Subject: Re: [PATCH 01/26] fscrypto: Add buffer operations

On Fri, Oct 21, 2016 at 03:17:03PM +0200, Richard Weinberger wrote:
> UBIFS works on kmalloc()'ed buffers where it constructs the NAND/NOR pages
> which will be written to the MTD. JFFS2 does the same.

Yes, you can trivially do a virt_to_page on a kmalloc buffer.

> Another reason why I did the buffer functions is because fscrypt_encrypt_page()
> always allocates a bounce page as temporary memory. For ext4 this is needed,
> for UBIFS not.
> UBIFS has already a construction buffer, especially since it also does compression.

We should defintively find a way to avoid that, but it's a separate
issue from adding another API just to pass buffers.