linux-ext4 - Re: [PATCH v4 3/3] ext4: unconditionally enable the i

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Date:   Fri, 12 Aug 2022 15:05:30 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Lukas Czerner <lczerner@...hat.com>
Cc:     linux-ext4@...r.kernel.org, tytso@....edu, jlayton@...nel.org,
        jack@...e.cz, linux-fsdevel@...r.kernel.org, ebiggers@...nel.org,
        david@...morbit.com, Benjamin Coddington <bcodding@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Darrick J . Wong" <djwong@...nel.org>
Subject: Re: [PATCH v4 3/3] ext4: unconditionally enable the i_version counter

On Fri, Aug 12, 2022 at 02:37:27PM +0200, Lukas Czerner wrote:
> From: Jeff Layton <jlayton@...nel.org>
> 
> The original i_version implementation was pretty expensive, requiring a
> log flush on every change. Because of this, it was gated behind a mount
> option (implemented via the MS_I_VERSION mountoption flag).
> 
> Commit ae5e165d855d (fs: new API for handling inode->i_version) made the
> i_version flag much less expensive, so there is no longer a performance
> penalty from enabling it. xfs and btrfs already enable it
> unconditionally when the on-disk format can support it.
> 
> Have ext4 ignore the SB_I_VERSION flag, and just enable it
> unconditionally. While we're in here, remove the handling of
> Opt_i_version as well, since we're almost to 5.20 anyway.
> 
> Ideally, we'd couple this change with a way to disable the i_version
> counter (just in case), but the way the iversion mount option was
> implemented makes that difficult to do. We'd need to add a new mount
> option altogether or do something with tune2fs. That's probably best
> left to later patches if it turns out to be needed.
> 
> [ Removed leftover bits of i_version from ext4_apply_options() since it
> now can't ever be set in ctx->mask_s_flags -- lczerner ]
> 
> Cc: Dave Chinner <david@...morbit.com>
> Cc: Benjamin Coddington <bcodding@...hat.com>
> Cc: Christoph Hellwig <hch@...radead.org>
> Cc: Darrick J. Wong <djwong@...nel.org>
> Signed-off-by: Jeff Layton <jlayton@...nel.org>
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> ---

Since ext4 seems to ignore unknown mount options in ext4_parse_param()
removing seems good,
Reviewed-by: Christian Brauner (Microsoft) <brauner@...nel.org>