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Subject[PATCH 3.12 082/144] ceph: Avoid data inconsistency due to d-cache aliasing in readpage()
Date
3.12-stable review patch.  If anyone has any objections, please let me know.

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

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