f2fs: fix incorrect calculation with total/free inode num

Theoretically, our total inodes number is the same as total node number, but
there are three node ids are reserved in f2fs, they are 0, 1 (node nid), and 2
(meta nid), and they should never be used by user, so our total/free inode
number calculated in ->statfs is wrong.

This patch indroduces F2FS_RESERVED_NODE_NUM and then fixes this issue by
recalculating total/free inode number with the macro.

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

3 files changed, 6 insertions, 3 deletions

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index b4d964029fc7..044395c20ee9 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1957,7 +1957,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
         nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks;
 
         /* not used nids: 0, node, meta, (and root counted as valid node) */
-        nm_i->available_nids = nm_i->max_nid - 3;
+        nm_i->available_nids = nm_i->max_nid - F2FS_RESERVED_NODE_NUM;
         nm_i->fcnt = 0;
         nm_i->nat_cnt = 0;
         nm_i->ram_thresh = DEF_RAM_THRESHOLD;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index ddb1e9d36363..0f61f5aa587c 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -508,8 +508,8 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
         buf->f_bfree = buf->f_blocks - valid_user_blocks(sbi) - ovp_count;
         buf->f_bavail = user_block_count - valid_user_blocks(sbi);
 
-        buf->f_files = sbi->total_node_count;
-        buf->f_ffree = sbi->total_node_count - valid_inode_count(sbi);
+        buf->f_files = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
+        buf->f_ffree = buf->f_files - valid_inode_count(sbi);
 
         buf->f_namelen = F2FS_NAME_LEN;
         buf->f_fsid.val[0] = (u32)id;
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index 6ff0b0b42d47..0ed77f32c9ac 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -24,6 +24,9 @@
 #define NULL_ADDR               ((block_t)0)    /* used as block_t addresses */
 #define NEW_ADDR                ((block_t)-1)   /* used as block_t addresses */
 
+/* 0, 1(node nid), 2(meta nid) are reserved node id */
+#define F2FS_RESERVED_NODE_NUM          3
+
 #define F2FS_ROOT_INO(sbi)      (sbi->root_ino_num)
 #define F2FS_NODE_INO(sbi)      (sbi->node_ino_num)
 #define F2FS_META_INO(sbi)      (sbi->meta_ino_num)