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From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>, Matthew Wilcox <willy@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Vineet Gupta <vgupta@synopsys.com>
Subject: [PATCH 01/71] arc: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
Date: Sun, 20 Mar 2016 21:40:08 +0300
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PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago
with promise that one day it will be possible to implement page cache with
bigger chunks than PAGE_SIZE.

This promise never materialized. And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_*
or PAGE_* constant should be used in a particular case, especially on the
border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special. They are not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/cache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index b65f797e9ad6..d9bacb4199ea 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -621,7 +621,7 @@ void flush_dcache_page(struct page *page)
 
 		/* kernel reading from page with U-mapping */
 		phys_addr_t paddr = (unsigned long)page_address(page);
-		unsigned long vaddr = page->index << PAGE_CACHE_SHIFT;
+		unsigned long vaddr = page->index << PAGE_SHIFT;
 
 		if (addr_not_cache_congruent(paddr, vaddr))
 			__flush_dcache_page(paddr, vaddr);
-- 
2.7.0