ARC: [mm] Assume pagecache page dirty by default

Similar to ARM/SH
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/cacheflush.h

@@ -80,6 +80,13 @@ void flush_anon_page(struct vm_area_struct *vma,
 
 #endif	/* CONFIG_ARC_CACHE_VIPT_ALIASING */
 
+/*
+ * A new pagecache page has PG_arch_1 clear - thus dcache dirty by default
+ * This works around some PIO based drivers which don't call flush_dcache_page
+ * to record that they dirtied the dcache
+ */
+#define PG_dc_clean	PG_arch_1
+
 /*
  * Simple wrapper over config option
  * Bootup code ensures that hardware matches kernel configuration

arch/arc/mm/cache_arc700.c

@@ -512,7 +512,7 @@ void flush_dcache_page(struct page *page)
 	struct address_space *mapping;
 
 	if (!cache_is_vipt_aliasing()) {
-		set_bit(PG_arch_1, &page->flags);
+		clear_bit(PG_dc_clean, &page->flags);
 		return;
 	}
 
@@ -526,7 +526,7 @@ void flush_dcache_page(struct page *page)
 	 * Make a note that K-mapping is dirty
 	 */
 	if (!mapping_mapped(mapping)) {
-		set_bit(PG_arch_1, &page->flags);
+		clear_bit(PG_dc_clean, &page->flags);
 	} else if (page_mapped(page)) {
 
 		/* kernel reading from page with U-mapping */
@@ -734,7 +734,7 @@ void copy_user_highpage(struct page *to, struct page *from,
 	 * non copied user pages (e.g. read faults which wire in pagecache page
 	 * directly).
 	 */
-	set_bit(PG_arch_1, &to->flags);
+	clear_bit(PG_dc_clean, &to->flags);
 
 	/*
 	 * if SRC was already usermapped and non-congruent to kernel mapping
@@ -742,16 +742,16 @@ void copy_user_highpage(struct page *to, struct page *from,
 	 */
 	if (clean_src_k_mappings) {
 		__flush_dcache_page(kfrom, kfrom);
-		clear_bit(PG_arch_1, &from->flags);
+		set_bit(PG_dc_clean, &from->flags);
 	} else {
-		set_bit(PG_arch_1, &from->flags);
+		clear_bit(PG_dc_clean, &from->flags);
 	}
 }
 
 void clear_user_page(void *to, unsigned long u_vaddr, struct page *page)
 {
 	clear_page(to);
-	set_bit(PG_arch_1, &page->flags);
+	clear_bit(PG_dc_clean, &page->flags);
 }
 
 

arch/arc/mm/tlb.c

@@ -453,7 +453,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr_unaligned,
 	if ((vma->vm_flags & VM_EXEC) ||
 	     addr_not_cache_congruent(paddr, vaddr)) {
 
-		int dirty = test_and_clear_bit(PG_arch_1, &page->flags);
+		int dirty = !test_and_set_bit(PG_dc_clean, &page->flags);
 		if (dirty) {
 			/* wback + inv dcache lines */
 			__flush_dcache_page(paddr, paddr);