From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Wang Subject: Re: [PATCH] Ceph: Avoid data inconsistency due to d-cache aliasing in readpage() Date: Wed, 13 Nov 2013 22:37:17 +0800 Message-ID: <52838E9D.7010901@ubuntukylin.com> References: <1384327335-18812-1-git-send-email-liwang@ubuntukylin.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: ceph-devel , Sage Weil , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: "Yan, Zheng" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hi Yan, zero_user_segment() has invoked flush_dcache_page() for us, we donnot wanna flush d-cache twice. Cheers, Li Wang On 11/13/2013 09:19 PM, Yan, Zheng wrote: > On Wed, Nov 13, 2013 at 3:22 PM, Li Wang wrote: >> If the length of data to be read in readpage() is exactly >> PAGE_CACHE_SIZE, the original code does not flush d-cache >> for data consistency after finishing reading. This patches fixes >> this. >> >> Signed-off-by: Li Wang >> --- >> fs/ceph/addr.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c >> index 6df8bd4..7b0000a 100644 >> --- a/fs/ceph/addr.c >> +++ b/fs/ceph/addr.c >> @@ -210,9 +210,13 @@ static int readpage_nounlock(struct file *filp, struct page *page) >> if (err < 0) { >> SetPageError(page); >> goto out; >> - } else if (err < PAGE_CACHE_SIZE) { >> + } else { >> + if (err < PAGE_CACHE_SIZE) { >> /* zero fill remainder of page */ >> - zero_user_segment(page, err, PAGE_CACHE_SIZE); >> + zero_user_segment(page, err, PAGE_CACHE_SIZE); >> + } else { >> + flush_dcache_page(page); >> + } > > this doesn't make sense for me. why not call flush_dcache_page unconditionally? > > Regards > Yan, Zheng >> } >> SetPageUptodate(page); >> >> -- >> 1.7.9.5 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Please read the FAQ at http://www.tux.org/lkml/ >