linux-kernel - [PATCH 5/5] hugetlbfs: fix confusing hugetlbfs stat

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Message-ID: <20220721131637.6306-6-linmiaohe@huawei.com>
Date:   Thu, 21 Jul 2022 21:16:37 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <mike.kravetz@...cle.com>,
        <songmuchun@...edance.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 5/5] hugetlbfs: fix confusing hugetlbfs stat

When size option is not specified, f_blocks, f_bavail and f_bfree will be
set to -1 instead of 0. Likewise, when nr_inodes is not specified, f_files
and f_ffree will be set to -1 too. Check max_hpages and max_inodes against
-1 first to make sure 0 is reported for max/free/used when no limit is set
as the comment states.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 fs/hugetlbfs/inode.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 19fc62a9c2fe..44da9828e171 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1083,16 +1083,20 @@ static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 		/* If no limits set, just report 0 for max/free/used
 		 * blocks, like simple_statfs() */
 		if (sbinfo->spool) {
-			long free_pages;
-
 			spin_lock_irq(&sbinfo->spool->lock);
-			buf->f_blocks = sbinfo->spool->max_hpages;
-			free_pages = sbinfo->spool->max_hpages
-				- sbinfo->spool->used_hpages;
-			buf->f_bavail = buf->f_bfree = free_pages;
+			if (sbinfo->spool->max_hpages != -1) {
+				long free_pages;
+
+				buf->f_blocks = sbinfo->spool->max_hpages;
+				free_pages = sbinfo->spool->max_hpages
+					     - sbinfo->spool->used_hpages;
+				buf->f_bavail = buf->f_bfree = free_pages;
+			}
 			spin_unlock_irq(&sbinfo->spool->lock);
-			buf->f_files = sbinfo->max_inodes;
-			buf->f_ffree = sbinfo->free_inodes;
+			if (sbinfo->max_inodes != -1) {
+				buf->f_files = sbinfo->max_inodes;
+				buf->f_ffree = sbinfo->free_inodes;
+			}
 		}
 		spin_unlock(&sbinfo->stat_lock);
 	}
-- 
2.23.0