f2fs: fix miscounted block limit in f2fs_statfs_project()

statfs calculates Total/Used/Avail disk space in block unit,
so we should translate soft/hard prjquota limit to block unit
as well.

Below testing result shows the block/inode numbers of
Total/Used/Avail from df command are all correct afer
applying this patch.

[root@localhost quota-tools]\# ./repquota -P /dev/sdb1
*** Report for project quotas on device /dev/sdb1
Block grace time: 7days; Inode grace time: 7days
              Block limits                File limits
Project   used soft    hard  grace  used  soft  hard  grace
-----------------------------------------------------------
\#0   --   4       0       0         1     0     0
\torvalds#101 --   0       0       0         2     0     0
\torvalds#102 --   0   10240       0         2    10     0
\torvalds#103 --   0       0   20480         2     0    20
\torvalds#104 --   0   10240   20480         2    10    20
\torvalds#105 --   0   20480   10240         2    20    10

[root@localhost sdb1]\# lsattr -p t{1,2,3,4,5}
  101 ----------------N-- t1/a1
  102 ----------------N-- t2/a2
  103 ----------------N-- t3/a3
  104 ----------------N-- t4/a4
  105 ----------------N-- t5/a5

[root@localhost sdb1]\# df -hi t{1,2,3,4,5}
Filesystem     Inodes IUsed IFree IUse% Mounted on
/dev/sdb1        2.4M    21  2.4M    1% /mnt/sdb1
/dev/sdb1          10     2     8   20% /mnt/sdb1
/dev/sdb1          20     2    18   10% /mnt/sdb1
/dev/sdb1          10     2     8   20% /mnt/sdb1
/dev/sdb1          10     2     8   20% /mnt/sdb1

[root@localhost sdb1]\# df -h t{1,2,3,4,5}
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdb1        10G  489M  9.6G   5% /mnt/sdb1
/dev/sdb1        10M     0   10M   0% /mnt/sdb1
/dev/sdb1        20M     0   20M   0% /mnt/sdb1
/dev/sdb1        10M     0   10M   0% /mnt/sdb1
/dev/sdb1        10M     0   10M   0% /mnt/sdb1

Fixes: 909110c ("f2fs: choose hardlimit when softlimit is larger than hardlimit in f2fs_statfs_project()")
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>

fs/f2fs/super.c

@@ -1288,6 +1288,8 @@ static int f2fs_statfs_project(struct super_block *sb,
 	if (dquot->dq_dqb.dqb_bhardlimit &&
 			(!limit || dquot->dq_dqb.dqb_bhardlimit < limit))
 		limit = dquot->dq_dqb.dqb_bhardlimit;
+	if (limit)
+		limit >>= sb->s_blocksize_bits;
 
 	if (limit && buf->f_blocks > limit) {
 		curblock = dquot->dq_dqb.dqb_curspace >> sb->s_blocksize_bits;