linux-kernel - [PATCH 13/71] nvdimm: get rid of PAGE_CACHE_* and page_cache

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Date:	Sun, 20 Mar 2016 21:40:20 +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>,
	Dan Williams <dan.j.williams@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>
Subject: [PATCH 13/71] nvdimm: 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: Dan Williams <dan.j.williams@...el.com>
Cc: Vishal Verma <vishal.l.verma@...el.com>
Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>
---
 drivers/nvdimm/btt.c  | 2 +-
 drivers/nvdimm/pmem.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index c32cbb593600..f068b6513cd2 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1204,7 +1204,7 @@ static int btt_rw_page(struct block_device *bdev, sector_t sector,
 {
 	struct btt *btt = bdev->bd_disk->private_data;
 
-	btt_do_bvec(btt, NULL, page, PAGE_CACHE_SIZE, 0, rw, sector);
+	btt_do_bvec(btt, NULL, page, PAGE_SIZE, 0, rw, sector);
 	page_endio(page, rw & WRITE, 0);
 	return 0;
 }
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index ca5721c306bb..a1a29c711532 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -151,7 +151,7 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
 	struct pmem_device *pmem = bdev->bd_disk->private_data;
 	int rc;
 
-	rc = pmem_do_bvec(pmem, page, PAGE_CACHE_SIZE, 0, rw, sector);
+	rc = pmem_do_bvec(pmem, page, PAGE_SIZE, 0, rw, sector);
 	if (rw & WRITE)
 		wmb_pmem();
 
-- 
2.7.0