[RFC 10/23] xen/biomerge: WORKAROUND always says the biovec are not mergeable

From: Julien Grall
Date: Thu May 14 2015 - 13:21:55 EST


When Linux is using 64K page granularity, every page will be slipt in
multiple non-contiguous 4K MFN.

I'm not sure how to handle efficiently the check to know whether we can
merge 2 biovec with a such case. So for now, always says that biovec are
not mergeable.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
---
drivers/xen/biomerge.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/xen/biomerge.c b/drivers/xen/biomerge.c
index 0edb91c..20387c2 100644
--- a/drivers/xen/biomerge.c
+++ b/drivers/xen/biomerge.c
@@ -9,6 +9,9 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
unsigned long mfn1 = pfn_to_mfn(page_to_pfn(vec1->bv_page));
unsigned long mfn2 = pfn_to_mfn(page_to_pfn(vec2->bv_page));

+ /* TODO: Implement it correctly */
+ return 0;
+
return __BIOVEC_PHYS_MERGEABLE(vec1, vec2) &&
((mfn1 == mfn2) || ((mfn1+1) == mfn2));
}
--
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/