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 3e68ac1..5da06f0 100644 (file)
--- 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);