On Sat 09-06-12 09:50:36, Akinobu Mita wrote:
> 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 <akinobu.mita@xxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
Acked-by: Jan Kara <jack@xxxxxxx>
Honza
> Cc: linux-ext4@xxxxxxxxxxxxxxx
> ---
> 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;
> --
> 1.7.7.6
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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