linux-kernel - [PATCH 3.12 082/144] ceph: Avoid data inconsistency due to d-cache aliasing in readpage()

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Message-Id: <20140106223747.708728592@linuxfoundation.org>
Date:	Mon,  6 Jan 2014 14:37:23 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Li Wang <liwang@...ntukylin.com>,
	Sage Weil <sage@...tank.com>
Subject: [PATCH 3.12 082/144] ceph: Avoid data inconsistency due to d-cache aliasing in readpage()

3.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Li Wang <liwang@...ntukylin.com>

commit 56f91aad69444d650237295f68c195b74d888d95 upstream.

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 <liwang@...ntukylin.com>
Signed-off-by: Sage Weil <sage@...tank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ceph/addr.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -210,9 +210,13 @@ static int readpage_nounlock(struct file
 	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);
+		}
 	}
 	SetPageUptodate(page);
 


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