Re: [PATCH v4 00/20] change invalidatepage prototype to accept length

Lukáš Czerner
2013-05-21T14:34:25Z

On Tue, 14 May 2013, Lukas Czerner wrote:

> Date: Tue, 14 May 2013 18:37:14 +0200
> From: Lukas Czerner <lczerner@redhat.com>
> To: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
> linux-ext4@vger.kernel.org, akpm@linux-foundation.org, hughd@google.com,
> lczerner@redhat.com
> Subject: [PATCH v4 00/20] change invalidatepage prototype to accept length

Hi Ted,

you've mentioned that you'll carry the changed in the ext4 tree. Are
you going to take it for the next merge window ?

However I still need some review on the mm part of the series,
Andrew, Hugh, anyone ?

Thanks!
-Lukas

>
> Hi,
>
> This set of patches are aimed to allow truncate_inode_pages_range() handle
> ranges which are not aligned at the end of the page. Currently it will
> hit BUG_ON() when the end of the range is not aligned. Punch hole feature
> however can benefit from this ability saving file systems some work not
> forcing them to implement their own invalidate code to handle unaligned
> ranges.
>
> In order for this to woke we need change ->invalidatepage() address space
> operation to to accept range to invalidate by adding 'length' argument in
> addition to 'offset'. This is different from my previous attempt to create
> new aop ->invalidatepage_range (http://lwn.net/Articles/514828/) which I
> reconsidered to be unnecessary.
>
> It would be for the best if this series could go through ext4 branch since
> there are a lot of ext4 changes which are based on dev branch of ext4
> (git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git)
>
> For description purposes this patch set can be divided into following
> groups:
>
> patch 0001: Change ->invalidatepage() prototype adding 'length' argument
> and changing all the instances. In very simple cases file
> system methods are completely adapted, otherwise only
> prototype is changed and the rest will follow. This patch
> also implement the 'range' invalidation in
> block_invalidatepage().
>
> patch 0002 - 0009:
> Make the use of new 'length' argument in the file system
> itself. Some file systems can take advantage of it trying
> to invalidate only portion of the page if possible, some
> can't, however none of the file systems currently attempt
> to truncate non page aligned ranges.
>
>
> patch 0010: Teach truncate_inode_pages_range() to handle non page aligned
> ranges.
>
> patch 0011 - 0020:
> Ext4 changes build on top of previous changes, simplifying
> punch hole code. Not all changes are realated specifically
> to invalidatepage() change, but all are related to the punch
> hole feature.
>
> Even though this patch set would mainly affect functionality of the file
> file systems implementing punch hole I've tested all the following file
> system using xfstests without noticing any bugs related to this change.
>
> ext3, ext4, xfs, btrfs, gfs2 and reiserfs
>
> I've also tested block size < page size on ext4 with xfstests and fsx.
>
>
> v3 -> v4: Some minor changes based on the reviews. Added two ext4 patches
> as suggested by Jan Kara.
>
> Thanks!
> -Lukas
>
>