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: Fan li <fanofcode.li@samsung.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 97799bd503cc06f7b0081f897efbfd540515f990..be6fb809f5191cc4770eb279ff18bb51e8a4f812 100644 (file)
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1955,6 +1955,7 @@ 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);
 
@@ -1964,10 +1965,10 @@ 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);
@@ -1980,7 +1981,6 @@ 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));