lkml.org 
[lkml]   [2012]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v3 2/9] qnx4fs: use memweight()
Date
Use memweight() to count the total number of bits clear in memory area.

Note that this memweight() call can't be replaced with a single
bitmap_weight() call, although the pointer to the memory area is
aligned to long-word boundary. Because the size of the memory area
may not be a multiple of BITS_PER_LONG, then it returns wrong value on
big-endian architecture.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Anders Larsen <al@alarsen.net>
---
v3: add note in the patch description
v2: put whitespace before '-'
fs/qnx4/bitmap.c | 24 +++++-------------------
1 files changed, 5 insertions(+), 19 deletions(-)
diff --git a/fs/qnx4/bitmap.c b/fs/qnx4/bitmap.c
index 22e0d60..76a7a69 100644
--- a/fs/qnx4/bitmap.c
+++ b/fs/qnx4/bitmap.c
@@ -17,23 +17,6 @@
#include <linux/bitops.h>
#include "qnx4.h"

-static void count_bits(register const char *bmPart, register int size,
- int *const tf)
-{
- char b;
- int tot = *tf;
-
- if (size > QNX4_BLOCK_SIZE) {
- size = QNX4_BLOCK_SIZE;
- }
- do {
- b = *bmPart++;
- tot += 8 - hweight8(b);
- size--;
- } while (size != 0);
- *tf = tot;
-}
-
unsigned long qnx4_count_free_blocks(struct super_block *sb)
{
int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
@@ -44,13 +27,16 @@ unsigned long qnx4_count_free_blocks(struct super_block *sb)
struct buffer_head *bh;

while (total < size) {
+ int bytes = min(size - total, QNX4_BLOCK_SIZE);
+
if ((bh = sb_bread(sb, start + offset)) == NULL) {
printk(KERN_ERR "qnx4: I/O error in counting free blocks\n");
break;
}
- count_bits(bh->b_data, size - total, &total_free);
+ total_free += bytes * BITS_PER_BYTE -
+ memweight(bh->b_data, bytes);
brelse(bh);
- total += QNX4_BLOCK_SIZE;
+ total += bytes;
offset++;
}

--
1.7.7.6


\
 
 \ /
  Last update: 2012-06-09 03:41    [from the cache]
©2003-2011 Jasper Spaans