From: "Lukáš Czerner" <lczerner@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Lukas Czerner <lczerner@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH v2 10/18] mm: teach truncate_inode_pages_range() to handle non page aligned ranges
Date: Fri, 8 Feb 2013 10:08:05 +0100 (CET) [thread overview]
Message-ID: <alpine.LFD.2.00.1302080948110.3225@localhost> (raw)
In-Reply-To: <20130207154042.92430aed.akpm@linux-foundation.org>
On Thu, 7 Feb 2013, Andrew Morton wrote:
> Date: Thu, 7 Feb 2013 15:40:42 -0800
> From: Andrew Morton <akpm@linux-foundation.org>
> To: Lukas Czerner <lczerner@redhat.com>
> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
> linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
> Hugh Dickins <hughd@google.com>
> Subject: Re: [PATCH v2 10/18] mm: teach truncate_inode_pages_range() to handle
> non page aligned ranges
>
> On Tue, 5 Feb 2013 10:12:03 +0100
> Lukas Czerner <lczerner@redhat.com> wrote:
>
> > This commit changes truncate_inode_pages_range() so it can handle non
> > page aligned regions of the truncate. Currently we can hit BUG_ON when
> > the end of the range is not page aligned, but we can handle unaligned
> > start of the range.
> >
> > Being able to handle non page aligned regions of the page can help file
> > system punch_hole implementations and save some work, because once we're
> > holding the page we might as well deal with it right away.
> >
> > In previous commits we've changed ->invalidatepage() prototype to accept
> > 'length' argument to be able to specify range to invalidate. No we can
> > use that new ability in truncate_inode_pages_range().
> >
> > ...
> >
> > + /*
> > + * 'start' and 'end' always covers the range of pages to be fully
> > + * truncated. Partial pages are covered with 'partial_start' at the
> > + * start of the range and 'partial_end' at the end of the range.
> > + * Note that 'end' is exclusive while 'lend' is inclusive.
> > + */
>
> That helped ;) So the bytes to be truncated are
>
> (start*PAGE_SIZE + partial_start) -> (end*PAGE_SIZE + partial_end) - 1
>
> yes?
The start of the range is not right, because 'start' and 'end'
covers pages to be _fully_ truncated. See the while cycle and
then 'if (partial_start)' condition where we search for the
page (start - 1) and do_invalidate within that page.
So it should be like this:
(start*PAGE_SIZE - partial_start*(PAGE_SIZE - partial_start) ->
(end*PAGE_END + partial_end) - 1
assuming that you want the range to be inclusive on both sides.
-Lukas
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next prev parent reply other threads:[~2013-02-08 9:08 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-05 9:11 [PATCH v2 00/18] change invalidatepage prototype to accept length Lukas Czerner
2013-02-05 9:11 ` [PATCH v2 01/18] mm: " Lukas Czerner
2013-02-05 9:11 ` [PATCH v2 02/18] jbd2: change jbd2_journal_invalidatepage " Lukas Czerner
2013-02-05 9:11 ` [PATCH v2 03/18] ext4: use ->invalidatepage() length argument Lukas Czerner
2013-02-05 9:11 ` [PATCH v2 04/18] jbd: change journal_invalidatepage() to accept length Lukas Czerner
2013-02-05 9:11 ` [PATCH v2 05/18] xfs: use ->invalidatepage() length argument Lukas Czerner
2013-02-05 9:11 ` [PATCH v2 06/18] ocfs2: " Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 07/18] ceph: " Lukas Czerner
2013-02-05 16:39 ` Sage Weil
2013-02-05 9:12 ` [PATCH v2 08/18] gfs2: " Lukas Czerner
2013-02-05 9:47 ` [Cluster-devel] " Steven Whitehouse
2013-02-05 9:12 ` [PATCH v2 09/18] reiserfs: " Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 10/18] mm: teach truncate_inode_pages_range() to handle non page aligned ranges Lukas Czerner
2013-02-07 23:40 ` Andrew Morton
2013-02-08 9:08 ` Lukáš Czerner [this message]
2013-02-21 8:33 ` Lukáš Czerner
2013-02-21 21:49 ` Andrew Morton
2013-02-22 8:06 ` Lukáš Czerner
2013-02-05 9:12 ` [PATCH v2 11/18] Revert "ext4: remove no longer used functions in inode.c" Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 12/18] Revert "ext4: fix fsx truncate failure" Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 13/18] ext4: use ext4_zero_partial_blocks in punch_hole Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 14/18] ext4: remove unused discard_partial_page_buffers Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 15/18] ext4: remove unused code from ext4_remove_blocks() Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 16/18] ext4: update ext4_ext_remove_space trace point Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 17/18] ext4: make punch hole code path work with bigalloc Lukas Czerner
2013-02-05 9:12 ` [PATCH v2 18/18] ext4: Allow punch hole with bigalloc enabled Lukas Czerner
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