f2fs: add available_nids to fix handling max_nid correctly

This patch introduces available_nids for alloc_nids() and fixes max_nid for
build_free_nids() and scan_nat_pages().

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

2 files changed, 5 insertions, 2 deletions

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 55152de1118c..556d06b67e6a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -244,6 +244,7 @@ static inline void set_raw_extent(struct extent_info *ext,
 struct f2fs_nm_info {
         block_t nat_blkaddr;            /* base disk address of NAT */
         nid_t max_nid;                  /* maximum possible node ids */
+        nid_t available_nids;           /* maximum available node ids */
         nid_t next_scan_nid;            /* the next nid to be scanned */
         unsigned int ram_thresh;        /* control the memory footprint */
 
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 837f5fdabd19..6ebdba151f12 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1447,7 +1447,7 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid)
         struct f2fs_nm_info *nm_i = NM_I(sbi);
         struct free_nid *i = NULL;
 retry:
-        if (unlikely(sbi->total_valid_node_count + 1 >= nm_i->max_nid))
+        if (unlikely(sbi->total_valid_node_count + 1 > nm_i->available_nids))
                 return false;
 
         spin_lock(&nm_i->free_nid_list_lock);
@@ -1859,8 +1859,10 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
         nat_segs = le32_to_cpu(sb_raw->segment_count_nat) >> 1;
         nat_blocks = nat_segs << le32_to_cpu(sb_raw->log_blocks_per_seg);
 
+        nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks;
+
         /* not used nids: 0, node, meta, (and root counted as valid node) */
-        nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks - 3;
+        nm_i->available_nids = nm_i->max_nid - 3;
         nm_i->fcnt = 0;
         nm_i->nat_cnt = 0;
         nm_i->ram_thresh = DEF_RAM_THRESHOLD;