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/nilfs2/mdt.c

@@ -110,7 +110,7 @@ static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
 
  failed_bh:
 	unlock_page(bh->b_page);
-	page_cache_release(bh->b_page);
+	put_page(bh->b_page);
 	brelse(bh);
 
  failed_unlock:
@@ -170,7 +170,7 @@ nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
 
  failed_bh:
 	unlock_page(bh->b_page);
-	page_cache_release(bh->b_page);
+	put_page(bh->b_page);
 	brelse(bh);
  failed:
 	return ret;
@@ -363,7 +363,7 @@ int nilfs_mdt_delete_block(struct inode *inode, unsigned long block)
 int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
 {
 	pgoff_t index = (pgoff_t)block >>
-		(PAGE_CACHE_SHIFT - inode->i_blkbits);
+		(PAGE_SHIFT - inode->i_blkbits);
 	struct page *page;
 	unsigned long first_block;
 	int ret = 0;
@@ -376,7 +376,7 @@ int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
 	wait_on_page_writeback(page);
 
 	first_block = (unsigned long)index <<
-		(PAGE_CACHE_SHIFT - inode->i_blkbits);
+		(PAGE_SHIFT - inode->i_blkbits);
 	if (page_has_buffers(page)) {
 		struct buffer_head *bh;
 
@@ -385,7 +385,7 @@ int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
 	}
 	still_dirty = PageDirty(page);
 	unlock_page(page);
-	page_cache_release(page);
+	put_page(page);
 
 	if (still_dirty ||
 	    invalidate_inode_pages2_range(inode->i_mapping, index, index) != 0)
@@ -578,7 +578,7 @@ int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
 	}
 
 	unlock_page(page);
-	page_cache_release(page);
+	put_page(page);
 	return 0;
 }
 
@@ -597,7 +597,7 @@ nilfs_mdt_get_frozen_buffer(struct inode *inode, struct buffer_head *bh)
 			bh_frozen = nilfs_page_get_nth_block(page, n);
 		}
 		unlock_page(page);
-		page_cache_release(page);
+		put_page(page);
 	}
 	return bh_frozen;
 }