linux-kernel - [PATCH 09/71] v4l: get rid of PAGE_CACHE_* and page_cache

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Date:	Sun, 20 Mar 2016 21:40:16 +0300
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Christoph Lameter <cl@...ux.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>
Subject: [PATCH 09/71] v4l: get rid of PAGE_CACHE_* and page_cache_{get,release} macros

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@...ux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab@....samsung.com>
---
 drivers/media/v4l2-core/videobuf-dma-sg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c
index f669cedca8bd..f4c212911b44 100644
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -350,7 +350,7 @@ int videobuf_dma_free(struct videobuf_dmabuf *dma)

 	if (dma->pages) {
 		for (i = 0; i < dma->nr_pages; i++)
-			page_cache_release(dma->pages[i]);
+			put_page(dma->pages[i]);
 		kfree(dma->pages);
 		dma->pages = NULL;
 	}
-- 
2.7.0