[f2fs-dev] [PATCH] f2fs: choose hardlimit when softlimit is larger than hardlimit in f2fs_statfs_project()

[Chengguang Xu <cgxu519@mykernel.net>]

Setting softlimit larger than hardlimit seems meaningless
for disk quota but currently it is allowed. In this case,
there may be a bit of comfusion for users when they run
df comamnd to directory which has project quota.

For example, we set 20M softlimit and 10M hardlimit of
block usage limit for project quota of test_dir(project id 123).

[root@hades f2fs]# repquota -P -a
*** Report for project quotas on device /dev/nvme0n1p8
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
123      +-   10248   20480   10240              2     0     0

The result of df command as below:

[root@hades f2fs]# df -h /mnt/f2fs/test
Filesystem      Size  Used Avail Use% Mounted on
/dev/nvme0n1p8   20M   11M   10M  51% /mnt/f2fs

Even though it looks like there is another 10M free space to use,
if we write new data to diretory test(inherit project id),
the write will fail with errno(-EDQUOT).

After this patch, the df result looks like below.

[root@hades f2fs]# df -h /mnt/f2fs/test
Filesystem      Size  Used Avail Use% Mounted on
/dev/nvme0n1p8   10M   10M     0 100% /mnt/f2fs

Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
---
 fs/f2fs/super.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 1443cee15863..5bf6e619a8e2 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1213,9 +1213,15 @@ static int f2fs_statfs_project(struct super_block *sb,
 		return PTR_ERR(dquot);
 	spin_lock(&dquot->dq_dqb_lock);
 
-	limit = (dquot->dq_dqb.dqb_bsoftlimit ?
-		 dquot->dq_dqb.dqb_bsoftlimit :
-		 dquot->dq_dqb.dqb_bhardlimit) >> sb->s_blocksize_bits;
+	limit = 0;
+	if (dquot->dq_dqb.dqb_bsoftlimit &&
+	   (!limit || dquot->dq_dqb.dqb_bsoftlimit < limit))
+		limit = dquot->dq_dqb.dqb_bsoftlimit;
+	if (dquot->dq_dqb.dqb_bhardlimit &&
+	   (!limit || dquot->dq_dqb.dqb_bhardlimit < limit))
+		limit = dquot->dq_dqb.dqb_bhardlimit;
+	limit >>= sb->s_blocksize_bits;
+
 	if (limit && buf->f_blocks > limit) {
 		curblock = dquot->dq_dqb.dqb_curspace >> sb->s_blocksize_bits;
 		buf->f_blocks = limit;
@@ -1224,9 +1230,14 @@ static int f2fs_statfs_project(struct super_block *sb,
 			 (buf->f_blocks - curblock) : 0;
 	}
 
-	limit = dquot->dq_dqb.dqb_isoftlimit ?
-		dquot->dq_dqb.dqb_isoftlimit :
-		dquot->dq_dqb.dqb_ihardlimit;
+	limit = 0;
+	if (dquot->dq_dqb.dqb_isoftlimit &&
+	   (!limit || dquot->dq_dqb.dqb_isoftlimit < limit))
+		limit = dquot->dq_dqb.dqb_isoftlimit;
+	if (dquot->dq_dqb.dqb_ihardlimit &&
+	   (!limit || dquot->dq_dqb.dqb_ihardlimit < limit))
+		limit = dquot->dq_dqb.dqb_ihardlimit;
+
 	if (limit && buf->f_files > limit) {
 		buf->f_files = limit;
 		buf->f_ffree =
-- 
2.20.1





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