[PATCH 2/3] f2fs: fix get stale meta pages when build free nids

[Wanpeng Li <wanpeng.li@linux.intel.com>]

The blocks of nat pages to be scanned will be readahead when build free 
nids. The start blkno will be adjusted to 0 when the intended range over 
max_nids, then function ra_meta_pages readahead the right blkno, however, 
function get_current_nat_page which is called in build_free_nids still 
get the meta pages w/ stale blkno, this patch fix it by adjusting the nid 
and the blkno which will be readahead in avdance in order to readahead and 
get the right meta pages.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
 fs/f2fs/checkpoint.c | 3 ---
 fs/f2fs/node.c       | 9 ++++++++-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 53bc328..aedb441 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -129,9 +129,6 @@ int ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages, int type
 
 		switch (type) {
 		case META_NAT:
-			if (unlikely(blkno >=
-					NAT_BLOCK_OFFSET(NM_I(sbi)->max_nid)))
-				blkno = 0;
 			/* get nat block addr */
 			fio.blk_addr = current_nat_addr(sbi,
 					blkno * NAT_ENTRY_PER_BLOCK);
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 1a7e925..8751375 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1509,13 +1509,20 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
 	struct f2fs_summary_block *sum = curseg->sum_blk;
 	int i = 0;
 	nid_t nid = nm_i->next_scan_nid;
+	block_t blkno = NAT_BLOCK_OFFSET(nid);
 
 	/* Enough entries */
 	if (nm_i->fcnt > NAT_ENTRY_PER_BLOCK)
 		return;
 
+	if (unlikely(blkno >=
+			NAT_BLOCK_OFFSET(NM_I(sbi)->max_nid))) {
+		blkno = 0;
+		nid = 0;
+	}
+
 	/* readahead nat pages to be scanned */
-	ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), FREE_NID_PAGES, META_NAT);
+	ra_meta_pages(sbi, blkno, FREE_NID_PAGES, META_NAT);
 
 	while (1) {
 		struct page *page = get_current_nat_page(sbi, nid);
-- 
1.9.1