From 2ed21dae021db1f9f988494ceee519290217520d Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Mon, 13 May 2013 17:23:58 +0530
Subject: [PATCH] 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 |  7 +++++++
 arch/arc/mm/cache_arc700.c        | 12 ++++++------
 arch/arc/mm/tlb.c                 |  2 +-
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/arch/arc/include/asm/cacheflush.h b/arch/arc/include/asm/cacheflush.h
index 185dfd03dcdb..6abc4972bc93 100644
--- a/arch/arc/include/asm/cacheflush.h
+++ b/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
diff --git a/arch/arc/mm/cache_arc700.c b/arch/arc/mm/cache_arc700.c
index 074658704d86..66c75ee16e50 100644
--- a/arch/arc/mm/cache_arc700.c
+++ b/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);
 }
 
 
diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index 1c91dbc8ddd8..d44ae33c2d1e 100644
--- a/arch/arc/mm/tlb.c
+++ b/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);
-- 
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