d8e0420603
Impact: allow Xen control of bio merging When running in Xen domain with device access, we need to make sure the block subsystem doesn't merge requests across pages which aren't machine physically contiguous. To do this, we define our own BIOVEC_PHYS_MERGEABLE. When CONFIG_XEN isn't enabled, or we're not running in a Xen domain, this has identical behaviour to the normal implementation. When running under Xen, we also make sure the underlying machine pages are the same or adjacent. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
14 lines
383 B
C
14 lines
383 B
C
#include <linux/bio.h>
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#include <linux/io.h>
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#include <xen/page.h>
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bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
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const struct bio_vec *vec2)
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{
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unsigned long mfn1 = pfn_to_mfn(page_to_pfn(vec1->bv_page));
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unsigned long mfn2 = pfn_to_mfn(page_to_pfn(vec2->bv_page));
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return __BIOVEC_PHYS_MERGEABLE(vec1, vec2) &&
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((mfn1 == mfn2) || ((mfn1+1) == mfn2));
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}
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