linux-ext4 - Re: [RFC PATCH 00/10] Consolidate Post read processing code

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Message-ID: <20190219211715.GA12177@gmail.com>
Date:   Tue, 19 Feb 2019 13:17:16 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     Chandan Rajendra <chandan@...ux.ibm.com>
Cc:     linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-fscrypt@...r.kernel.org, tytso@....edu,
        adilger.kernel@...ger.ca, jaegeuk@...nel.org, yuchao0@...wei.com
Subject: Re: [RFC PATCH 00/10] Consolidate Post read processing code

Hi Chandan,

On Mon, Feb 18, 2019 at 03:34:23PM +0530, Chandan Rajendra wrote:
> This patchset moves the "post read processing" code into a file of its
> own and gets the generic do_mpage_readpge() to make use of the
> functionality provided. With these changes in place, the patchset
> changes Ext4 to use mpage_readpage[s] instead of its own custom
> ext4_readpages() function. This is done to reduce duplicity of code
> across filesystems. Based on the reviews provided for this patchset, I
> will change F2FS to use mpage_readpage[s] and post the next version of
> this patchset to linux-fsdevel mailing list.
> 
> The patchset also includes patches from previous postings i.e.
> patches to replace per-filesystem encryption config options with a
> single config option that affects all filesystems making use of
> fscrypt code.
> 
> Chandan Rajendra (10):
>   ext4: use IS_ENCRYPTED() to check encryption status
>   f2fs: use IS_ENCRYPTED() to check encryption status
>   fscrypt: remove filesystem specific build config option
>   Consolidate "post read processing" into a new file
>   fsverity: Add call back to decide if verity check has to be performed
>   Introduce REQ_POST_READ_PROC bio flag
>   fsverity: Add call back to determine readpage limit
>   fsverity: Add call back to verify file holes
>   fs/mpage.c: Integrate post read processing
>   ext4: Wire up ext4_readpage[s] to use mpage_readpage[s]
> 

Thanks for working on this!  This will also make it much easier to support
block_size != PAGE_SIZE in ext4 encryption, right?  I think this is the best
path forward, but I'll take a closer look at your new patches.

FYI regarding practical matters, merging fs-verity was delayed due to
disagreement about the API.  See https://lwn.net/Articles/775872/.

We don't have to wait for fs-verity for your initial fscrypt changes, though:

	ext4: use IS_ENCRYPTED() to check encryption status
	f2fs: use IS_ENCRYPTED() to check encryption status
	fscrypt: remove filesystem specific build config option

So, a couple weeks ago Ted and I already queued those three patches in
fscrypt.git (https://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt.git
branch "master", though we plan to change the repo soon) for the upcoming merge
window, based on upstream rather than fs-verity.  Are you fine with that?

I also suggest adding linux-fsdevel to the Cc given the fs/*.c changes.

Thanks!

- Eric