mm, fs: 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>;

 - <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();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/ocfs2.h

@@ -822,10 +822,10 @@ static inline unsigned int ocfs2_page_index_to_clusters(struct super_block *sb,
 	u32 clusters = pg_index;
 	unsigned int cbits = OCFS2_SB(sb)->s_clustersize_bits;
 
-	if (unlikely(PAGE_CACHE_SHIFT > cbits))
-		clusters = pg_index << (PAGE_CACHE_SHIFT - cbits);
-	else if (PAGE_CACHE_SHIFT < cbits)
-		clusters = pg_index >> (cbits - PAGE_CACHE_SHIFT);
+	if (unlikely(PAGE_SHIFT > cbits))
+		clusters = pg_index << (PAGE_SHIFT - cbits);
+	else if (PAGE_SHIFT < cbits)
+		clusters = pg_index >> (cbits - PAGE_SHIFT);
 
 	return clusters;
 }
@@ -839,10 +839,10 @@ static inline pgoff_t ocfs2_align_clusters_to_page_index(struct super_block *sb,
 	unsigned int cbits = OCFS2_SB(sb)->s_clustersize_bits;
         pgoff_t index = clusters;
 
-	if (PAGE_CACHE_SHIFT > cbits) {
-		index = (pgoff_t)clusters >> (PAGE_CACHE_SHIFT - cbits);
-	} else if (PAGE_CACHE_SHIFT < cbits) {
-		index = (pgoff_t)clusters << (cbits - PAGE_CACHE_SHIFT);
+	if (PAGE_SHIFT > cbits) {
+		index = (pgoff_t)clusters >> (PAGE_SHIFT - cbits);
+	} else if (PAGE_SHIFT < cbits) {
+		index = (pgoff_t)clusters << (cbits - PAGE_SHIFT);
 	}
 
 	return index;
@@ -853,8 +853,8 @@ static inline unsigned int ocfs2_pages_per_cluster(struct super_block *sb)
 	unsigned int cbits = OCFS2_SB(sb)->s_clustersize_bits;
 	unsigned int pages_per_cluster = 1;
 
-	if (PAGE_CACHE_SHIFT < cbits)
-		pages_per_cluster = 1 << (cbits - PAGE_CACHE_SHIFT);
+	if (PAGE_SHIFT < cbits)
+		pages_per_cluster = 1 << (cbits - PAGE_SHIFT);
 
 	return pages_per_cluster;
 }