Previously, in __build_free_nids we try to load bitmap from next_scan_nid pointed NAT block, but actually, due to nat_bits bitmap, current NAT blocks readed can be already ran out, so it makes __build_free_nids low efficiency.
This patch refactors __build_free_nids a bit to search nat_block_bitmap first to find out which NAT blocks have not been loaded yet, and then do loading bitmaps. Signed-off-by: Chao Yu <[email protected]> --- fs/f2fs/node.c | 54 ++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 34 insertions(+), 20 deletions(-) diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index 4c758747980c..fb52622727ea 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -1865,13 +1865,13 @@ static void scan_curseg_cache(struct f2fs_sb_info *sbi, nid_t start_nid, up_read(&curseg->journal_rwsem); } -static void scan_nat_page(struct f2fs_sb_info *sbi, nid_t nid) +static void scan_nat_page(struct f2fs_sb_info *sbi, unsigned int nat_ofs) { struct f2fs_nm_info *nm_i = NM_I(sbi); struct page *page; struct f2fs_nat_block *nat_blk; block_t blk_addr; - unsigned int nat_ofs = NAT_BLOCK_OFFSET(nid); + nid_t nid = nat_ofs * NAT_ENTRY_PER_BLOCK; nid_t start_nid = nid; int i; @@ -1935,37 +1935,51 @@ static nid_t lookup_free_nid_bitmap(struct f2fs_sb_info *sbi) static void __build_free_nids(struct f2fs_sb_info *sbi, bool mount) { struct f2fs_nm_info *nm_i = NM_I(sbi); - int i = 0; - nid_t nid = nm_i->next_scan_nid; + unsigned int pos, start, end, max_cnt = nm_i->nat_blocks; + bool sync_ra = true; - if (unlikely(nid >= nm_i->max_nid)) - nid = 0; + if (unlikely(nm_i->next_scan_nid >= nm_i->max_nid)) + nm_i->next_scan_nid = 0; /* Enough entries */ if (!mount && nm_i->available_free_nids >= NAT_ENTRY_PER_BLOCK) return; - /* readahead nat pages to be scanned */ - ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), FREE_NID_PAGES, - META_NAT, true); + start = NAT_BLOCK_OFFSET(nm_i->next_scan_nid); - down_read(&nm_i->nat_tree_lock); +readahead: + /* search unloaded bitmap in range of [start, max] */ + pos = find_next_zero_bit_le(nm_i->nat_block_bitmap, max_cnt, start); + if (pos >= max_cnt) { + if (!start) + return; + /* search unloaded bitmap in range of [0, start] */ + pos = find_next_zero_bit_le(nm_i->nat_block_bitmap, start, 0); + if (pos >= start) + return; + } - do { - scan_nat_page(sbi, nid); + end = find_next_bit_le(nm_i->nat_block_bitmap, max_cnt, pos); + end = min(end, start + FREE_NID_PAGES); - nid += (NAT_ENTRY_PER_BLOCK - (nid % NAT_ENTRY_PER_BLOCK)); - if (unlikely(nid >= nm_i->max_nid)) - nid = 0; - } while (++i < FREE_NID_PAGES); + /* readahead nat pages to be scanned */ + ra_meta_pages(sbi, pos, end - pos, META_NAT, sync_ra); - /* go to the next free nat pages to find free nids abundantly */ - nm_i->next_scan_nid = nid; + if (!sync_ra) + return; + down_read(&nm_i->nat_tree_lock); + for (; pos < end; pos++) + scan_nat_page(sbi, pos); up_read(&nm_i->nat_tree_lock); - ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nm_i->next_scan_nid), - nm_i->ra_nid_pages, META_NAT, false); + /* go to the next free nat pages to find free nids abundantly */ + nm_i->next_scan_nid = end * NAT_ENTRY_PER_BLOCK; + + /* do async readahead for continual nid allocation */ + start = NAT_BLOCK_OFFSET(nm_i->next_scan_nid); + sync_ra = false; + goto readahead; } void build_free_nids(struct f2fs_sb_info *sbi, bool mount) -- 2.15.0.55.gc2ece9dc4de6
