coccinelle: api: add vma_pages.cocci

This semantic patch replaces explicit computations of vma page count
with explicit function call.
Signed-off-by: Dmitry Kalinkin <dmitry.kalinkin@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/api/vma_pages.cocci

+///
+/// Use vma_pages function on vma object instead of explicit computation.
+///
+//  Confidence: High
+//  Keywords: vma_pages vma
+//  Comment: Based on resource_size.cocci
+
+virtual context
+virtual patch
+virtual org
+virtual report
+
+//----------------------------------------------------------
+//  For context mode
+//----------------------------------------------------------
+
+@r_context depends on context && !patch && !org && !report@
+struct vm_area_struct *vma;
+@@
+
+* (vma->vm_end - vma->vm_start) >> PAGE_SHIFT
+
+//----------------------------------------------------------
+//  For patch mode
+//----------------------------------------------------------
+
+@r_patch depends on !context && patch && !org && !report@
+struct vm_area_struct *vma;
+@@
+
+- ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)
++ vma_pages(vma)
+
+//----------------------------------------------------------
+//  For org mode
+//----------------------------------------------------------
+
+@r_org depends on !context && !patch && (org || report)@
+struct vm_area_struct *vma;
+position p;
+@@
+
+  (vma->vm_end@p - vma->vm_start) >> PAGE_SHIFT
+
+@script:python depends on report@
+p << r_org.p;
+x << r_org.vma;
+@@
+
+msg="WARNING: Consider using vma_pages helper on %s" % (x)
+coccilib.report.print_report(p[0], msg)
+
+@script:python depends on org@
+p << r_org.p;
+x << r_org.vma;
+@@
+
+msg="WARNING: Consider using vma_pages helper on %s" % (x)
+msg_safe=msg.replace("[","@(").replace("]",")")
+coccilib.org.print_todo(p[0], msg_safe)