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/btrfs/raid56.c

@@ -270,7 +270,7 @@ static void cache_rbio_pages(struct btrfs_raid_bio *rbio)
 		s = kmap(rbio->bio_pages[i]);
 		d = kmap(rbio->stripe_pages[i]);
 
-		memcpy(d, s, PAGE_CACHE_SIZE);
+		memcpy(d, s, PAGE_SIZE);
 
 		kunmap(rbio->bio_pages[i]);
 		kunmap(rbio->stripe_pages[i]);
@@ -962,7 +962,7 @@ static struct page *page_in_rbio(struct btrfs_raid_bio *rbio,
  */
 static unsigned long rbio_nr_pages(unsigned long stripe_len, int nr_stripes)
 {
-	return DIV_ROUND_UP(stripe_len, PAGE_CACHE_SIZE) * nr_stripes;
+	return DIV_ROUND_UP(stripe_len, PAGE_SIZE) * nr_stripes;
 }
 
 /*
@@ -1078,7 +1078,7 @@ static int rbio_add_io_page(struct btrfs_raid_bio *rbio,
 	u64 disk_start;
 
 	stripe = &rbio->bbio->stripes[stripe_nr];
-	disk_start = stripe->physical + (page_index << PAGE_CACHE_SHIFT);
+	disk_start = stripe->physical + (page_index << PAGE_SHIFT);
 
 	/* if the device is missing, just fail this stripe */
 	if (!stripe->dev->bdev)
@@ -1096,8 +1096,8 @@ static int rbio_add_io_page(struct btrfs_raid_bio *rbio,
 		if (last_end == disk_start && stripe->dev->bdev &&
 		    !last->bi_error &&
 		    last->bi_bdev == stripe->dev->bdev) {
-			ret = bio_add_page(last, page, PAGE_CACHE_SIZE, 0);
-			if (ret == PAGE_CACHE_SIZE)
+			ret = bio_add_page(last, page, PAGE_SIZE, 0);
+			if (ret == PAGE_SIZE)
 				return 0;
 		}
 	}
@@ -1111,7 +1111,7 @@ static int rbio_add_io_page(struct btrfs_raid_bio *rbio,
 	bio->bi_bdev = stripe->dev->bdev;
 	bio->bi_iter.bi_sector = disk_start >> 9;
 
-	bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
+	bio_add_page(bio, page, PAGE_SIZE, 0);
 	bio_list_add(bio_list, bio);
 	return 0;
 }
@@ -1154,7 +1154,7 @@ static void index_rbio_pages(struct btrfs_raid_bio *rbio)
 	bio_list_for_each(bio, &rbio->bio_list) {
 		start = (u64)bio->bi_iter.bi_sector << 9;
 		stripe_offset = start - rbio->bbio->raid_map[0];
-		page_index = stripe_offset >> PAGE_CACHE_SHIFT;
+		page_index = stripe_offset >> PAGE_SHIFT;
 
 		for (i = 0; i < bio->bi_vcnt; i++) {
 			p = bio->bi_io_vec[i].bv_page;
@@ -1253,7 +1253,7 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
 		} else {
 			/* raid5 */
 			memcpy(pointers[nr_data], pointers[0], PAGE_SIZE);
-			run_xor(pointers + 1, nr_data - 1, PAGE_CACHE_SIZE);
+			run_xor(pointers + 1, nr_data - 1, PAGE_SIZE);
 		}
 
 
@@ -1914,7 +1914,7 @@ pstripe:
 			/* Copy parity block into failed block to start with */
 			memcpy(pointers[faila],
 			       pointers[rbio->nr_data],
-			       PAGE_CACHE_SIZE);
+			       PAGE_SIZE);
 
 			/* rearrange the pointer array */
 			p = pointers[faila];
@@ -1923,7 +1923,7 @@ pstripe:
 			pointers[rbio->nr_data - 1] = p;
 
 			/* xor in the rest */
-			run_xor(pointers, rbio->nr_data - 1, PAGE_CACHE_SIZE);
+			run_xor(pointers, rbio->nr_data - 1, PAGE_SIZE);
 		}
 		/* if we're doing this rebuild as part of an rmw, go through
 		 * and set all of our private rbio pages in the
@@ -2250,7 +2250,7 @@ void raid56_add_scrub_pages(struct btrfs_raid_bio *rbio, struct page *page,
 	ASSERT(logical + PAGE_SIZE <= rbio->bbio->raid_map[0] +
 				rbio->stripe_len * rbio->nr_data);
 	stripe_offset = (int)(logical - rbio->bbio->raid_map[0]);
-	index = stripe_offset >> PAGE_CACHE_SHIFT;
+	index = stripe_offset >> PAGE_SHIFT;
 	rbio->bio_pages[index] = page;
 }
 
@@ -2365,14 +2365,14 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
 		} else {
 			/* raid5 */
 			memcpy(pointers[nr_data], pointers[0], PAGE_SIZE);
-			run_xor(pointers + 1, nr_data - 1, PAGE_CACHE_SIZE);
+			run_xor(pointers + 1, nr_data - 1, PAGE_SIZE);
 		}
 
 		/* Check scrubbing pairty and repair it */
 		p = rbio_stripe_page(rbio, rbio->scrubp, pagenr);
 		parity = kmap(p);
-		if (memcmp(parity, pointers[rbio->scrubp], PAGE_CACHE_SIZE))
-			memcpy(parity, pointers[rbio->scrubp], PAGE_CACHE_SIZE);
+		if (memcmp(parity, pointers[rbio->scrubp], PAGE_SIZE))
+			memcpy(parity, pointers[rbio->scrubp], PAGE_SIZE);
 		else
 			/* Parity is right, needn't writeback */
 			bitmap_clear(rbio->dbitmap, pagenr, 1);