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Commit 59b90517 authored by Fan Li's avatar Fan Li Committed by Jaegeuk Kim
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f2fs: optimize the way of traversing free_nid_bitmap 



We call scan_free_nid_bits only when there isn't many
free nids left, it means that marked bits in free_nid_bitmap
are supposed to be few, use find_next_bit_le is more
efficient in such case.
According to my tests, use find_next_bit_le instead of
test_bit_le will cut down the traversal time to one
third of its original.

Signed-off-by: default avatarFan li <fanofcode.li@samsung.com>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent d3754d20

fs/f2fs/node.c

+5 −5
Original line number Diff line number Diff line
@@ -1959,6 +1959,7 @@ static void scan_free_nid_bits(struct f2fs_sb_info *sbi) 
	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);

	struct f2fs_journal *journal = curseg->journal;

	unsigned int i, idx;

	nid_t nid;



	down_read(&nm_i->nat_tree_lock);
@@ -1968,10 +1969,10 @@ static void scan_free_nid_bits(struct f2fs_sb_info *sbi) 
		if (!nm_i->free_nid_count[i])

			continue;

		for (idx = 0; idx < NAT_ENTRY_PER_BLOCK; idx++) {

			nid_t nid;



			if (!test_bit_le(idx, nm_i->free_nid_bitmap[i]))

				continue;

			idx = find_next_bit_le(nm_i->free_nid_bitmap[i],

						NAT_ENTRY_PER_BLOCK, idx);

			if (idx >= NAT_ENTRY_PER_BLOCK)

				break;



			nid = i * NAT_ENTRY_PER_BLOCK + idx;

			add_free_nid(sbi, nid, true);
@@ -1984,7 +1985,6 @@ out: 
	down_read(&curseg->journal_rwsem);

	for (i = 0; i < nats_in_cursum(journal); i++) {

		block_t addr;

		nid_t nid;



		addr = le32_to_cpu(nat_in_journal(journal, i).block_addr);

		nid = le32_to_cpu(nid_in_journal(journal, i));