linux-kernel - [PATCH 5.1 279/405] block: avoid to break XEN by multi-page bvec

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Date:   Wed, 29 May 2019 20:04:37 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, ris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org, Omar Sandoval <osandov@...com>,
        Christoph Hellwig <hch@....de>,
        Juergen Gross <jgross@...e.com>,
        Ming Lei <ming.lei@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 279/405] block: avoid to break XEN by multi-page bvec

[ Upstream commit db5ebd6edd2627d7e81a031643cf43587f63e66c ]

XEN has special page merge requirement, see xen_biovec_phys_mergeable().
We can't merge pages into one bvec simply for XEN.

So move XEN's specific check on page merge into __bio_try_merge_page(),
then abvoid to break XEN by multi-page bvec.

Cc: ris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: xen-devel@...ts.xenproject.org
Cc: Omar Sandoval <osandov@...com>
Cc: Christoph Hellwig <hch@....de>
Reviewed-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/bio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index 716510ecd7ffa..a3c80a6c1fe51 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -776,6 +776,8 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page,
 
 		if (vec_end_addr + 1 != page_addr + off)
 			return false;
+		if (xen_domain() && !xen_biovec_phys_mergeable(bv, page))
+			return false;
 		if (same_page && (vec_end_addr & PAGE_MASK) != page_addr)
 			return false;
 
-- 
2.20.1