Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934643Ab2FIAwZ (ORCPT ); Fri, 8 Jun 2012 20:52:25 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:50988 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934543Ab2FIAv1 (ORCPT ); Fri, 8 Jun 2012 20:51:27 -0400 From: Akinobu Mita To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: Akinobu Mita , "Theodore Ts'o" , Andreas Dilger , linux-ext4@vger.kernel.org Subject: [PATCH v3 9/9] ext4: use memweight() Date: Sat, 9 Jun 2012 09:50:38 +0900 Message-Id: <1339203038-13069-9-git-send-email-akinobu.mita@gmail.com> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <1339203038-13069-1-git-send-email-akinobu.mita@gmail.com> References: <1339203038-13069-1-git-send-email-akinobu.mita@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1918 Lines: 58 Convert ext4_count_free() to use memweight() instead of table lookup based counting clear bits implementation. This change only affects the code segments enabled by EXT4FS_DEBUG. 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. This also includes the following change. - Remove unnecessary map == NULL check in ext4_count_free() which always takes non-null pointer as the memory area. Signed-off-by: Akinobu Mita Cc: "Theodore Ts'o" Cc: Andreas Dilger Cc: linux-ext4@vger.kernel.org --- v3: rewrite to keep ext4_count_free() as a wrapper for memweight() v2: don't remove bitmap.c which now has other than ext4_count_free() fs/ext4/bitmap.c | 11 +---------- 1 files changed, 1 insertions(+), 10 deletions(-) diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c index b319721..ff53d5d 100644 --- a/fs/ext4/bitmap.c +++ b/fs/ext4/bitmap.c @@ -13,18 +13,9 @@ #ifdef EXT4FS_DEBUG -static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; - unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars) { - unsigned int i, sum = 0; - - if (!map) - return 0; - for (i = 0; i < numchars; i++) - sum += nibblemap[map->b_data[i] & 0xf] + - nibblemap[(map->b_data[i] >> 4) & 0xf]; - return sum; + return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars); } #endif /* EXT4FS_DEBUG */ -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/