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>

1 files changed, 10 insertions, 10 deletions

diff --git a/mm/readahead.c b/mm/readahead.c
index 20e58e8..40be3ae 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -47,11 +47,11 @@ static void read_cache_pages_invalidate_page(struct address_space *mapping,
 		if (!trylock_page(page))
 			BUG();
 		page->mapping = mapping;
-		do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
+		do_invalidatepage(page, 0, PAGE_SIZE);
 		page->mapping = NULL;
 		unlock_page(page);
 	}
-	page_cache_release(page);
+	put_page(page);
 }
 
 /*
@@ -93,14 +93,14 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
 			read_cache_pages_invalidate_page(mapping, page);
 			continue;
 		}
-		page_cache_release(page);
+		put_page(page);
 
 		ret = filler(data, page);
 		if (unlikely(ret)) {
 			read_cache_pages_invalidate_pages(mapping, pages);
 			break;
 		}
-		task_io_account_read(PAGE_CACHE_SIZE);
+		task_io_account_read(PAGE_SIZE);
 	}
 	return ret;
 }
@@ -130,7 +130,7 @@ static int read_pages(struct address_space *mapping, struct file *filp,
 				mapping_gfp_constraint(mapping, GFP_KERNEL))) {
 			mapping->a_ops->readpage(filp, page);
 		}
-		page_cache_release(page);
+		put_page(page);
 	}
 	ret = 0;
 
@@ -163,7 +163,7 @@ int __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
 	if (isize == 0)
 		goto out;
 
-	end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
+	end_index = ((isize - 1) >> PAGE_SHIFT);
 
 	/*
 	 * Preallocate as many pages as we will need.
@@ -216,7 +216,7 @@ int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
 	while (nr_to_read) {
 		int err;
 
-		unsigned long this_chunk = (2 * 1024 * 1024) / PAGE_CACHE_SIZE;
+		unsigned long this_chunk = (2 * 1024 * 1024) / PAGE_SIZE;
 
 		if (this_chunk > nr_to_read)
 			this_chunk = nr_to_read;
@@ -425,7 +425,7 @@ ondemand_readahead(struct address_space *mapping,
 	 * trivial case: (offset - prev_offset) == 1
 	 * unaligned reads: (offset - prev_offset) == 0
 	 */
-	prev_offset = (unsigned long long)ra->prev_pos >> PAGE_CACHE_SHIFT;
+	prev_offset = (unsigned long long)ra->prev_pos >> PAGE_SHIFT;
 	if (offset - prev_offset <= 1UL)
 		goto initial_readahead;
 
@@ -558,8 +558,8 @@ SYSCALL_DEFINE3(readahead, int, fd, loff_t, offset, size_t, count)
 	if (f.file) {
 		if (f.file->f_mode & FMODE_READ) {
 			struct address_space *mapping = f.file->f_mapping;
-			pgoff_t start = offset >> PAGE_CACHE_SHIFT;
-			pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
+			pgoff_t start = offset >> PAGE_SHIFT;
+			pgoff_t end = (offset + count - 1) >> PAGE_SHIFT;
 			unsigned long len = end - start + 1;
 			ret = do_readahead(mapping, f.file, start, len);
 		}