linux-kernel - [PATCH] ntfs: Use bitmap

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Date:	Mon, 16 Nov 2009 12:07:20 +0900
From:	Akinobu Mita <akinobu.mita@...il.com>
To:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Cc:	Akinobu Mita <akinobu.mita@...il.com>,
	Anton Altaparmakov <aia21@...tab.net>,
	Al Viro <viro@...iv.linux.org.uk>,
	linux-ntfs-dev@...ts.sourceforge.net
Subject: [PATCH] ntfs: Use bitmap_weight

Use bitmap_weight instead of doing hweight32 for each u32 element
in page

Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
Cc: Anton Altaparmakov <aia21@...tab.net>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: linux-ntfs-dev@...ts.sourceforge.net
---
 fs/ntfs/super.c |   25 +++++++++++++------------
 1 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 80b0477..55be660 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -31,6 +31,7 @@
 #include <linux/vfs.h>
 #include <linux/moduleparam.h>
 #include <linux/smp_lock.h>
+#include <linux/bitmap.h>
 
 #include "sysctl.h"
 #include "logfile.h"
@@ -2457,7 +2458,6 @@ static void ntfs_put_super(struct super_block *sb)
 static s64 get_nr_free_clusters(ntfs_volume *vol)
 {
 	s64 nr_free = vol->nr_clusters;
-	u32 *kaddr;
 	struct address_space *mapping = vol->lcnbmp_ino->i_mapping;
 	struct page *page;
 	pgoff_t index, max_index;
@@ -2476,7 +2476,8 @@ static s64 get_nr_free_clusters(ntfs_volume *vol)
 	ntfs_debug("Reading $Bitmap, max_index = 0x%lx, max_size = 0x%lx.",
 			max_index, PAGE_CACHE_SIZE / 4);
 	for (index = 0; index < max_index; index++) {
-		unsigned int i;
+		unsigned long *kaddr;
+
 		/*
 		 * Read the page from page cache, getting it from backing store
 		 * if necessary, and increment the use count.
@@ -2489,16 +2490,16 @@ static s64 get_nr_free_clusters(ntfs_volume *vol)
 			nr_free -= PAGE_CACHE_SIZE * 8;
 			continue;
 		}
-		kaddr = (u32*)kmap_atomic(page, KM_USER0);
+		kaddr = kmap_atomic(page, KM_USER0);
 		/*
-		 * For each 4 bytes, subtract the number of set bits. If this
+		 * Subtract the number of set bits. If this
 		 * is the last page and it is partial we don't really care as
 		 * it just means we do a little extra work but it won't affect
 		 * the result as all out of range bytes are set to zero by
 		 * ntfs_readpage().
 		 */
-	  	for (i = 0; i < PAGE_CACHE_SIZE / 4; i++)
-			nr_free -= (s64)hweight32(kaddr[i]);
+		nr_free -= bitmap_weight(kaddr,
+					PAGE_CACHE_SIZE * BITS_PER_BYTE);
 		kunmap_atomic(kaddr, KM_USER0);
 		page_cache_release(page);
 	}
@@ -2537,7 +2538,6 @@ static s64 get_nr_free_clusters(ntfs_volume *vol)
 static unsigned long __get_nr_free_mft_records(ntfs_volume *vol,
 		s64 nr_free, const pgoff_t max_index)
 {
-	u32 *kaddr;
 	struct address_space *mapping = vol->mftbmp_ino->i_mapping;
 	struct page *page;
 	pgoff_t index;
@@ -2547,7 +2547,8 @@ static unsigned long __get_nr_free_mft_records(ntfs_volume *vol,
 	ntfs_debug("Reading $MFT/$BITMAP, max_index = 0x%lx, max_size = "
 			"0x%lx.", max_index, PAGE_CACHE_SIZE / 4);
 	for (index = 0; index < max_index; index++) {
-		unsigned int i;
+		unsigned long *kaddr;
+
 		/*
 		 * Read the page from page cache, getting it from backing store
 		 * if necessary, and increment the use count.
@@ -2560,16 +2561,16 @@ static unsigned long __get_nr_free_mft_records(ntfs_volume *vol,
 			nr_free -= PAGE_CACHE_SIZE * 8;
 			continue;
 		}
-		kaddr = (u32*)kmap_atomic(page, KM_USER0);
+		kaddr = kmap_atomic(page, KM_USER0);
 		/*
-		 * For each 4 bytes, subtract the number of set bits. If this
+		 * Subtract the number of set bits. If this
 		 * is the last page and it is partial we don't really care as
 		 * it just means we do a little extra work but it won't affect
 		 * the result as all out of range bytes are set to zero by
 		 * ntfs_readpage().
 		 */
-	  	for (i = 0; i < PAGE_CACHE_SIZE / 4; i++)
-			nr_free -= (s64)hweight32(kaddr[i]);
+		nr_free -= bitmap_weight(kaddr,
+					PAGE_CACHE_SIZE * BITS_PER_BYTE);
 		kunmap_atomic(kaddr, KM_USER0);
 		page_cache_release(page);
 	}
-- 
1.6.5.1

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