[Xen-devel] [PATCH V3 02/10] block: avoid to break XEN by multi-page bvec

[Ming Lei <ming.lei@xxxxxxxxxx>]

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@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Cc: Omar Sandoval <osandov@xxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 block/bio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index b64cedc7f87c..b2423e7aae08 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;
 
-- 
2.9.5


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