From patchwork Sat Jun 9 00:50:36 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v3,7/9] ext2: use memweight() From: Akinobu Mita X-Patchwork-Id: 163876 Message-Id: <1339203038-13069-7-git-send-email-akinobu.mita@gmail.com> To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: Akinobu Mita , Jan Kara , linux-ext4@vger.kernel.org Date: Sat, 9 Jun 2012 09:50:36 +0900 Convert ext2_count_free() to use memweight() instead of table lookup based counting clear bits implementation. This change only affects the code segments enabled by EXT2FS_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 changes. - Remove unnecessary map == NULL check in ext2_count_free() which always takes non-null pointer as the memory area. - Fix printk format warning that only reveals with EXT2FS_DEBUG. Signed-off-by: Akinobu Mita Cc: Jan Kara Cc: linux-ext4@vger.kernel.org --- v3: rewrite to keep ext2_count_free() as a wrapper for memweight() fs/ext2/balloc.c | 14 ++------------ fs/ext2/ialloc.c | 1 + 2 files changed, 3 insertions(+), 12 deletions(-) diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c index 1c36139..376aa77 100644 --- a/fs/ext2/balloc.c +++ b/fs/ext2/balloc.c @@ -1444,19 +1444,9 @@ ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp) #ifdef EXT2FS_DEBUG -static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; - -unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars) +unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars) { - unsigned int i; - unsigned long 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 /* EXT2FS_DEBUG */ diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c index c13eb7b..8f370e01 100644 --- a/fs/ext2/ialloc.c +++ b/fs/ext2/ialloc.c @@ -644,6 +644,7 @@ unsigned long ext2_count_free_inodes (struct super_block * sb) } brelse(bitmap_bh); printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n", + (unsigned long) percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter), desc_count, bitmap_count); return desc_count;