From: Bob Peterson <rpeterso@redhat.com>
Subject: Re: [PATCH v3 08/18] gfs2: use ->invalidatepage() length argument
Date: Tue, 9 Apr 2013 09:09:20 -0400 (EDT)
Message-ID: <686810645.4576872.1365512960001.JavaMail.root@redhat.com>
References: <1365498867-27782-1-git-send-email-lczerner@redhat.com> <1365498867-27782-9-git-send-email-lczerner@redhat.com>
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Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
        cluster-devel@redhat.com
To: Lukas Czerner <lczerner@redhat.com>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <1365498867-27782-9-git-send-email-lczerner@redhat.com>
Sender: owner-linux-mm@kvack.org
List-Id: linux-ext4.vger.kernel.org

Hi,

----- Original Message -----
| ->invalidatepage() aop now accepts range to invalidate so we can make
| use of it in gfs2_invalidatepage().
| 
| Signed-off-by: Lukas Czerner <lczerner@redhat.com>
| Cc: cluster-devel@redhat.com
| ---
|  fs/gfs2/aops.c |    9 +++++++--
|  1 files changed, 7 insertions(+), 2 deletions(-)
| 
| diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
| index 37093ba..ea920bf 100644
| --- a/fs/gfs2/aops.c
| +++ b/fs/gfs2/aops.c
| @@ -947,24 +947,29 @@ static void gfs2_invalidatepage(struct page *page,
| unsigned int offset,
|  				unsigned int length)
|  {
|  	struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
| +	unsigned int stop = offset + length;
| +	int partial_page = (offset || length < PAGE_CACHE_SIZE);
|  	struct buffer_head *bh, *head;
|  	unsigned long pos = 0;
|  
|  	BUG_ON(!PageLocked(page));
| -	if (offset == 0)
| +	if (!partial_page)
|  		ClearPageChecked(page);
|  	if (!page_has_buffers(page))
|  		goto out;
|  
|  	bh = head = page_buffers(page);
|  	do {
| +		if (pos + bh->b_size > stop)
| +			return;
| +

I always regret it when I review something this early in the morning,
or post before the caffeine has taken full effect. But...
Shouldn't the statement above be (1) ">= stop" and (2) goto out;?

|  		if (offset <= pos)
|  			gfs2_discard(sdp, bh);
|  		pos += bh->b_size;
|  		bh = bh->b_this_page;
|  	} while (bh != head);
|  out:
| -	if (offset == 0)
| +	if (!partial_page)
|  		try_to_release_page(page, 0);
|  }

Regards,

Bob Peterson
Red Hat File Systems

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