From: Alex Elder <elder@inktank.com>
Date: Thu, 23 May 2013 01:54:25 +0000 (-0500)
Subject: rbd: flush dcache after zeroing page data
X-Git-Url: http://git.mmlx.us/?a=commitdiff_plain;h=350505e73f8c4d03dfef660f40a6f35d5ac12be6;p=linux-edison.git

rbd: flush dcache after zeroing page data

commit e215605417b87732c6debf65da6d953016a1e5bc upstream.

Neither zero_bio_chain() nor zero_pages() contains a call to flush
caches after zeroing a portion of a page.  This can cause problems
on architectures that have caches that allow virtual address
aliasing.

This resolves:
    http://tracker.ceph.com/issues/4777

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 8c7421af8f1..ccd3553a047 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1126,6 +1126,7 @@ static void zero_bio_chain(struct bio *chain, int start_ofs)
 				buf = bvec_kmap_irq(bv, &flags);
 				memset(buf + remainder, 0,
 				       bv->bv_len - remainder);
+				flush_dcache_page(bv->bv_page);
 				bvec_kunmap_irq(buf, &flags);
 			}
 			pos += bv->bv_len;
@@ -1158,6 +1159,7 @@ static void zero_pages(struct page **pages, u64 offset, u64 end)
 		local_irq_save(flags);
 		kaddr = kmap_atomic(*page);
 		memset(kaddr + page_offset, 0, length);
+		flush_dcache_page(*page);
 		kunmap_atomic(kaddr);
 		local_irq_restore(flags);