From: Li Wang <liwang@ubuntukylin.com>
Date: Wed, 13 Nov 2013 07:22:14 +0000 (+0800)
Subject: ceph: Avoid data inconsistency due to d-cache aliasing in readpage()
X-Git-Tag: firefly_0821_release~3679^2~3205
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=88285f766c96205ccf30afd3d0621401701ff26c;p=firefly-linux-kernel-4.4.55.git

ceph: Avoid data inconsistency due to d-cache aliasing in readpage()

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@ubuntukylin.com>
Signed-off-by: Sage Weil <sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 3e68ac101040..5da06f020986 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -213,9 +213,13 @@ 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);
+		}
 	}
 	SetPageUptodate(page);