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From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>, Matthew Wilcox <willy@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Dave Kleikamp <shaggy@kernel.org>
Subject: [PATCH 45/71] jfs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
Date: Sun, 20 Mar 2016 21:40:52 +0300
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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>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Kleikamp <shaggy@kernel.org>
---
 fs/jfs/jfs_metapage.c | 42 +++++++++++++++++++++---------------------
 fs/jfs/jfs_metapage.h |  4 ++--
 fs/jfs/super.c        |  2 +-
 3 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
index a3eb316b1ac3..b60e015cc757 100644
--- a/fs/jfs/jfs_metapage.c
+++ b/fs/jfs/jfs_metapage.c
@@ -80,7 +80,7 @@ static inline void lock_metapage(struct metapage *mp)
 static struct kmem_cache *metapage_cache;
 static mempool_t *metapage_mempool;
 
-#define MPS_PER_PAGE (PAGE_CACHE_SIZE >> L2PSIZE)
+#define MPS_PER_PAGE (PAGE_SIZE >> L2PSIZE)
 
 #if MPS_PER_PAGE > 1
 
@@ -316,7 +316,7 @@ static void last_write_complete(struct page *page)
 	struct metapage *mp;
 	unsigned int offset;
 
-	for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
+	for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 		mp = page_to_mp(page, offset);
 		if (mp && test_bit(META_io, &mp->flag)) {
 			if (mp->lsn)
@@ -366,12 +366,12 @@ static int metapage_writepage(struct page *page, struct writeback_control *wbc)
 	int bad_blocks = 0;
 
 	page_start = (sector_t)page->index <<
-		     (PAGE_CACHE_SHIFT - inode->i_blkbits);
+		     (PAGE_SHIFT - inode->i_blkbits);
 	BUG_ON(!PageLocked(page));
 	BUG_ON(PageWriteback(page));
 	set_page_writeback(page);
 
-	for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
+	for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 		mp = page_to_mp(page, offset);
 
 		if (!mp || !test_bit(META_dirty, &mp->flag))
@@ -416,7 +416,7 @@ static int metapage_writepage(struct page *page, struct writeback_control *wbc)
 			bio = NULL;
 		} else
 			inc_io(page);
-		xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits;
+		xlen = (PAGE_SIZE - offset) >> inode->i_blkbits;
 		pblock = metapage_get_blocks(inode, lblock, &xlen);
 		if (!pblock) {
 			printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
@@ -485,7 +485,7 @@ static int metapage_readpage(struct file *fp, struct page *page)
 	struct inode *inode = page->mapping->host;
 	struct bio *bio = NULL;
 	int block_offset;
-	int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
+	int blocks_per_page = PAGE_SIZE >> inode->i_blkbits;
 	sector_t page_start;	/* address of page in fs blocks */
 	sector_t pblock;
 	int xlen;
@@ -494,7 +494,7 @@ static int metapage_readpage(struct file *fp, struct page *page)
 
 	BUG_ON(!PageLocked(page));
 	page_start = (sector_t)page->index <<
-		     (PAGE_CACHE_SHIFT - inode->i_blkbits);
+		     (PAGE_SHIFT - inode->i_blkbits);
 
 	block_offset = 0;
 	while (block_offset < blocks_per_page) {
@@ -542,7 +542,7 @@ static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
 	int ret = 1;
 	int offset;
 
-	for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
+	for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 		mp = page_to_mp(page, offset);
 
 		if (!mp)
@@ -568,7 +568,7 @@ static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
 static void metapage_invalidatepage(struct page *page, unsigned int offset,
 				    unsigned int length)
 {
-	BUG_ON(offset || length < PAGE_CACHE_SIZE);
+	BUG_ON(offset || length < PAGE_SIZE);
 
 	BUG_ON(PageWriteback(page));
 
@@ -599,10 +599,10 @@ struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
 		 inode->i_ino, lblock, absolute);
 
 	l2bsize = inode->i_blkbits;
-	l2BlocksPerPage = PAGE_CACHE_SHIFT - l2bsize;
+	l2BlocksPerPage = PAGE_SHIFT - l2bsize;
 	page_index = lblock >> l2BlocksPerPage;
 	page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
-	if ((page_offset + size) > PAGE_CACHE_SIZE) {
+	if ((page_offset + size) > PAGE_SIZE) {
 		jfs_err("MetaData crosses page boundary!!");
 		jfs_err("lblock = %lx, size  = %d", lblock, size);
 		dump_stack();
@@ -621,7 +621,7 @@ struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
 		mapping = inode->i_mapping;
 	}
 
-	if (new && (PSIZE == PAGE_CACHE_SIZE)) {
+	if (new && (PSIZE == PAGE_SIZE)) {
 		page = grab_cache_page(mapping, page_index);
 		if (!page) {
 			jfs_err("grab_cache_page failed!");
@@ -693,7 +693,7 @@ unlock:
 void grab_metapage(struct metapage * mp)
 {
 	jfs_info("grab_metapage: mp = 0x%p", mp);
-	page_cache_get(mp->page);
+	get_page(mp->page);
 	lock_page(mp->page);
 	mp->count++;
 	lock_metapage(mp);
@@ -706,12 +706,12 @@ void force_metapage(struct metapage *mp)
 	jfs_info("force_metapage: mp = 0x%p", mp);
 	set_bit(META_forcewrite, &mp->flag);
 	clear_bit(META_sync, &mp->flag);
-	page_cache_get(page);
+	get_page(page);
 	lock_page(page);
 	set_page_dirty(page);
 	write_one_page(page, 1);
 	clear_bit(META_forcewrite, &mp->flag);
-	page_cache_release(page);
+	put_page(page);
 }
 
 void hold_metapage(struct metapage *mp)
@@ -726,7 +726,7 @@ void put_metapage(struct metapage *mp)
 		unlock_page(mp->page);
 		return;
 	}
-	page_cache_get(mp->page);
+	get_page(mp->page);
 	mp->count++;
 	lock_metapage(mp);
 	unlock_page(mp->page);
@@ -746,7 +746,7 @@ void release_metapage(struct metapage * mp)
 	assert(mp->count);
 	if (--mp->count || mp->nohomeok) {
 		unlock_page(page);
-		page_cache_release(page);
+		put_page(page);
 		return;
 	}
 
@@ -764,13 +764,13 @@ void release_metapage(struct metapage * mp)
 	drop_metapage(page, mp);
 
 	unlock_page(page);
-	page_cache_release(page);
+	put_page(page);
 }
 
 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 {
 	sector_t lblock;
-	int l2BlocksPerPage = PAGE_CACHE_SHIFT - ip->i_blkbits;
+	int l2BlocksPerPage = PAGE_SHIFT - ip->i_blkbits;
 	int BlocksPerPage = 1 << l2BlocksPerPage;
 	/* All callers are interested in block device's mapping */
 	struct address_space *mapping =
@@ -788,7 +788,7 @@ void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 		page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
 		if (!page)
 			continue;
-		for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
+		for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 			mp = page_to_mp(page, offset);
 			if (!mp)
 				continue;
@@ -803,7 +803,7 @@ void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 				remove_from_logsync(mp);
 		}
 		unlock_page(page);
-		page_cache_release(page);
+		put_page(page);
 	}
 }
 
diff --git a/fs/jfs/jfs_metapage.h b/fs/jfs/jfs_metapage.h
index 337e9e51ac06..a869fb4a20d6 100644
--- a/fs/jfs/jfs_metapage.h
+++ b/fs/jfs/jfs_metapage.h
@@ -106,7 +106,7 @@ static inline void metapage_nohomeok(struct metapage *mp)
 	lock_page(page);
 	if (!mp->nohomeok++) {
 		mark_metapage_dirty(mp);
-		page_cache_get(page);
+		get_page(page);
 		wait_on_page_writeback(page);
 	}
 	unlock_page(page);
@@ -128,7 +128,7 @@ static inline void metapage_wait_for_io(struct metapage *mp)
 static inline void _metapage_homeok(struct metapage *mp)
 {
 	if (!--mp->nohomeok)
-		page_cache_release(mp->page);
+		put_page(mp->page);
 }
 
 static inline void metapage_homeok(struct metapage *mp)
diff --git a/fs/jfs/super.c b/fs/jfs/super.c
index 4f5d85ba8e23..78d599198bf5 100644
--- a/fs/jfs/super.c
+++ b/fs/jfs/super.c
@@ -596,7 +596,7 @@ static int jfs_fill_super(struct super_block *sb, void *data, int silent)
 	 * Page cache is indexed by long.
 	 * I would use MAX_LFS_FILESIZE, but it's only half as big
 	 */
-	sb->s_maxbytes = min(((u64) PAGE_CACHE_SIZE << 32) - 1,
+	sb->s_maxbytes = min(((u64) PAGE_SIZE << 32) - 1,
 			     (u64)sb->s_maxbytes);
 #endif
 	sb->s_time_gran = 1;
-- 
2.7.0