From 5d0c667121bfc8be76d1580f485bddbe73465d1a Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Thu, 27 Feb 2014 13:57:53 +0900 Subject: [PATCH] f2fs: remove costly bit operations for f2fs_find_entry It turns out that a bit operation like find_next_bit is not always fast enough for f2fs_find_entry. Instead, it is pretty much simple and fast to traverse each dentries. Signed-off-by: Jaegeuk Kim --- fs/f2fs/dir.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c index d5a2c9ed9aa7..c3ea8f8cc80a 100644 --- a/fs/f2fs/dir.c +++ b/fs/f2fs/dir.c @@ -93,16 +93,20 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page, f2fs_hash_t namehash, struct page **res_page) { struct f2fs_dir_entry *de; - unsigned long bit_pos, end_pos, next_pos; + unsigned long bit_pos = 0; struct f2fs_dentry_block *dentry_blk = kmap(dentry_page); - int slots; + int max_len = 0; - bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap, - NR_DENTRY_IN_BLOCK, 0); while (bit_pos < NR_DENTRY_IN_BLOCK) { de = &dentry_blk->dentry[bit_pos]; - slots = GET_DENTRY_SLOTS(le16_to_cpu(de->name_len)); - + if (!test_bit_le(bit_pos, &dentry_blk->dentry_bitmap)) { + if (bit_pos == 0) + max_len = 1; + else if (!test_bit_le(bit_pos - 1, &dentry_blk->dentry_bitmap)) + max_len++; + bit_pos++; + continue; + } if (early_match_name(name, namelen, namehash, de)) { if (!memcmp(dentry_blk->filename[bit_pos], name, namelen)) { @@ -110,20 +114,18 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page, goto found; } } - next_pos = bit_pos + slots; - bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap, - NR_DENTRY_IN_BLOCK, next_pos); - if (bit_pos >= NR_DENTRY_IN_BLOCK) - end_pos = NR_DENTRY_IN_BLOCK; - else - end_pos = bit_pos; - if (*max_slots < end_pos - next_pos) - *max_slots = end_pos - next_pos; + if (max_len > *max_slots) { + *max_slots = max_len; + max_len = 0; + } + 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; } -- 2.34.1