linux-kernel - [PATCH 36/71] fscache: get rid of PAGE_CACHE_* and page_cache

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Date:	Sun, 20 Mar 2016 21:40:43 +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>,
	David Howells <dhowells@...hat.com>
Subject: [PATCH 36/71] fscache: 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: David Howells <dhowells@...hat.com>
---
 fs/fscache/page.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 6b35fc4860a0..3078b679fcd1 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -113,7 +113,7 @@ try_again:
 
 	wake_up_bit(&cookie->flags, 0);
 	if (xpage)
-		page_cache_release(xpage);
+		put_page(xpage);
 	__fscache_uncache_page(cookie, page);
 	return true;
 
@@ -164,7 +164,7 @@ static void fscache_end_page_write(struct fscache_object *object,
 	}
 	spin_unlock(&object->lock);
 	if (xpage)
-		page_cache_release(xpage);
+		put_page(xpage);
 }
 
 /*
@@ -884,7 +884,7 @@ void fscache_invalidate_writes(struct fscache_cookie *cookie)
 		spin_unlock(&cookie->stores_lock);
 
 		for (i = n - 1; i >= 0; i--)
-			page_cache_release(results[i]);
+			put_page(results[i]);
 	}
 
 	_leave("");
@@ -982,7 +982,7 @@ int __fscache_write_page(struct fscache_cookie *cookie,
 
 	radix_tree_tag_set(&cookie->stores, page->index,
 			   FSCACHE_COOKIE_PENDING_TAG);
-	page_cache_get(page);
+	get_page(page);
 
 	/* we only want one writer at a time, but we do need to queue new
 	 * writers after exclusive ops */
@@ -1026,7 +1026,7 @@ submit_failed:
 	radix_tree_delete(&cookie->stores, page->index);
 	spin_unlock(&cookie->stores_lock);
 	wake_cookie = __fscache_unuse_cookie(cookie);
-	page_cache_release(page);
+	put_page(page);
 	ret = -ENOBUFS;
 	goto nobufs;
 
-- 
2.7.0