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/exofs/inode.c

@@ -317,7 +317,7 @@ static int read_exec(struct page_collect *pcol)
 
 	if (!pcol->ios) {
 		int ret = ore_get_rw_state(&pcol->sbi->layout, &oi->oc, true,
-					     pcol->pg_first << PAGE_CACHE_SHIFT,
+					     pcol->pg_first << PAGE_SHIFT,
 					     pcol->length, &pcol->ios);
 
 		if (ret)
@@ -383,7 +383,7 @@ static int readpage_strip(void *data, struct page *page)
 	struct inode *inode = pcol->inode;
 	struct exofs_i_info *oi = exofs_i(inode);
 	loff_t i_size = i_size_read(inode);
-	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+	pgoff_t end_index = i_size >> PAGE_SHIFT;
 	size_t len;
 	int ret;
 
@@ -397,9 +397,9 @@ static int readpage_strip(void *data, struct page *page)
 	pcol->that_locked_page = page;
 
 	if (page->index < end_index)
-		len = PAGE_CACHE_SIZE;
+		len = PAGE_SIZE;
 	else if (page->index == end_index)
-		len = i_size & ~PAGE_CACHE_MASK;
+		len = i_size & ~PAGE_MASK;
 	else
 		len = 0;
 
@@ -442,8 +442,8 @@ try_again:
 			goto fail;
 	}
 
-	if (len != PAGE_CACHE_SIZE)
-		zero_user(page, len, PAGE_CACHE_SIZE - len);
+	if (len != PAGE_SIZE)
+		zero_user(page, len, PAGE_SIZE - len);
 
 	EXOFS_DBGMSG2("    readpage_strip(0x%lx, 0x%lx) len=0x%zx\n",
 		     inode->i_ino, page->index, len);
@@ -609,7 +609,7 @@ static void __r4w_put_page(void *priv, struct page *page)
 
 	if ((pcol->that_locked_page != page) && (ZERO_PAGE(0) != page)) {
 		EXOFS_DBGMSG2("index=0x%lx\n", page->index);
-		page_cache_release(page);
+		put_page(page);
 		return;
 	}
 	EXOFS_DBGMSG2("that_locked_page index=0x%lx\n",
@@ -633,7 +633,7 @@ static int write_exec(struct page_collect *pcol)
 
 	BUG_ON(pcol->ios);
 	ret = ore_get_rw_state(&pcol->sbi->layout, &oi->oc, false,
-				 pcol->pg_first << PAGE_CACHE_SHIFT,
+				 pcol->pg_first << PAGE_SHIFT,
 				 pcol->length, &pcol->ios);
 	if (unlikely(ret))
 		goto err;
@@ -696,7 +696,7 @@ static int writepage_strip(struct page *page,
 	struct inode *inode = pcol->inode;
 	struct exofs_i_info *oi = exofs_i(inode);
 	loff_t i_size = i_size_read(inode);
-	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+	pgoff_t end_index = i_size >> PAGE_SHIFT;
 	size_t len;
 	int ret;
 
@@ -708,9 +708,9 @@ static int writepage_strip(struct page *page,
 
 	if (page->index < end_index)
 		/* in this case, the page is within the limits of the file */
-		len = PAGE_CACHE_SIZE;
+		len = PAGE_SIZE;
 	else {
-		len = i_size & ~PAGE_CACHE_MASK;
+		len = i_size & ~PAGE_MASK;
 
 		if (page->index > end_index || !len) {
 			/* in this case, the page is outside the limits
@@ -790,10 +790,10 @@ static int exofs_writepages(struct address_space *mapping,
 	long start, end, expected_pages;
 	int ret;
 
-	start = wbc->range_start >> PAGE_CACHE_SHIFT;
+	start = wbc->range_start >> PAGE_SHIFT;
 	end = (wbc->range_end == LLONG_MAX) ?
 			start + mapping->nrpages :
-			wbc->range_end >> PAGE_CACHE_SHIFT;
+			wbc->range_end >> PAGE_SHIFT;
 
 	if (start || end)
 		expected_pages = end - start + 1;
@@ -881,15 +881,15 @@ int exofs_write_begin(struct file *file, struct address_space *mapping,
 	}
 
 	 /* read modify write */
-	if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
+	if (!PageUptodate(page) && (len != PAGE_SIZE)) {
 		loff_t i_size = i_size_read(mapping->host);
-		pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+		pgoff_t end_index = i_size >> PAGE_SHIFT;
 		size_t rlen;
 
 		if (page->index < end_index)
-			rlen = PAGE_CACHE_SIZE;
+			rlen = PAGE_SIZE;
 		else if (page->index == end_index)
-			rlen = i_size & ~PAGE_CACHE_MASK;
+			rlen = i_size & ~PAGE_MASK;
 		else
 			rlen = 0;