Hi, Gu

Unfortunately, find_next_bit isn't always better than test_bit.
Refer to commit 5d0c667121bfc8be76d1580f485bddbe73465d1a

I remember that
Perviously, Jaegeuk had changed find_next_bit to test_bit because
find_next_bit spent much cpu time in the case of there is lot of dentries like 
a postmark.
Sorry, I should have reported this quickly.

On Tue, Jun 24, 2014 at 06:20:41PM +0800, Gu Zheng wrote:
> Use find_next_bit_le rather than test_bit_le to improve search speed
> lightly.
> 
> Signed-off-by: Gu Zheng <guz.f...@cn.fujitsu.com>
> ---
>  fs/f2fs/dir.c |   43 +++++++++++++++++++++----------------------
>  1 files changed, 21 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index 3edd561..ba510fb 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -93,42 +93,41 @@ static struct f2fs_dir_entry *find_in_block(struct page 
> *dentry_page,
>                       const char *name, size_t namelen, int *max_slots,
>                       f2fs_hash_t namehash, struct page **res_page)
>  {
> -     struct f2fs_dir_entry *de;
> -     unsigned long bit_pos = 0;
> +     unsigned long bit_pos = 0, bit_start = 0;
>       struct f2fs_dentry_block *dentry_blk = kmap(dentry_page);
>       const void *dentry_bits = &dentry_blk->dentry_bitmap;
> -     int max_len = 0;
>  
> -     while (bit_pos < NR_DENTRY_IN_BLOCK) {
> -             if (!test_bit_le(bit_pos, dentry_bits)) {
> -                     if (bit_pos == 0)
> -                             max_len = 1;
> -                     else if (!test_bit_le(bit_pos - 1, dentry_bits))
> -                             max_len++;
> -                     bit_pos++;
> -                     continue;
> +     while (bit_start < NR_DENTRY_IN_BLOCK) {
> +             struct f2fs_dir_entry *de;
> +             int max_len = 0;
> +
> +             bit_pos = find_next_bit_le(dentry_bits,
> +                                     NR_DENTRY_IN_BLOCK, bit_start);
> +
> +             max_len = bit_pos - bit_start;
> +             if (max_len > *max_slots) {
> +                     *max_slots = max_len;
> +                     max_len = 0;
>               }
> +
> +             if (bit_pos >= NR_DENTRY_IN_BLOCK)
> +                     break;
> +
>               de = &dentry_blk->dentry[bit_pos];
>               if (early_match_name(name, namelen, namehash, de)) {
>                       if (!memcmp(dentry_blk->filename[bit_pos],
>                                                       name, namelen)) {
>                               *res_page = dentry_page;
> -                             goto found;
> +                             return de;
>                       }
>               }
> -             if (max_len > *max_slots) {
> -                     *max_slots = max_len;
> -                     max_len = 0;
> -             }
> -             bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
> +
> +             bit_start = bit_pos
> +                             + GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
>       }
>  
> -     de = NULL;
>       kunmap(dentry_page);
> -found:
> -     if (max_len > *max_slots)
> -             *max_slots = max_len;
> -     return de;
> +     return NULL;
>  }
>  
>  static struct f2fs_dir_entry *find_in_level(struct inode *dir,
> -- 
> 1.7.7

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