linux-kernel - Re: [PATCH] fscrypt: Factor out bio specific functions

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Message-ID: <20161219103929.GA16197@infradead.org>
Date:   Mon, 19 Dec 2016 02:39:29 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Eric Biggers <ebiggers3@...il.com>
Cc:     Richard Weinberger <richard@....at>,
        David Gstir <david@...ma-star.at>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-kernel@...r.kernel.org, jaegeuk@...nel.org, tytso@....edu,
        hch@...radead.org, arnd@...db.de, dedekind1@...il.com,
        linux-mtd@...ts.infradead.org, adrian.hunter@...el.com,
        linux-ext4@...r.kernel.org, ebiggers@...gle.com,
        rdunlap@...radead.org
Subject: Re: [PATCH] fscrypt: Factor out bio specific functions

On Fri, Dec 16, 2016 at 02:14:28PM -0800, Eric Biggers wrote:
> Hmm, it still seems weird to define fscrypt_zeroout_range() when it can't
> actually be used.  It looks like the problem is specifically the use of
> alloc_bounce_page() and do_page_crypto().  Would it be that bad to make those
> available in fscrypt_internal.h (not exported to filesystems)?

Sounds good to me.

> Also, it seems the actual problem is that fscrypt_zeroout_range() tries to be
> clever and reuse one bounce page over and over.  But this seems very inefficient
> because it has to wait for each block to be synchronously written out before
> moving on to the next.  I'm thinking it really should be updated to work more
> like the normal write path, and then it could use fscrypt_encrypt_page()...

That sounds even better, but might take a little more time.