Commit 5d0c6671 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

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: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent 8b8343fa

fs/f2fs/dir.c

+17 −15
Original line number Diff line number Diff line
@@ -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;

}