hugetlbfs: fix hugetlbfs_statfs() locking

After commit db71ef79 ("hugetlb: make free_huge_page irq safe"), the
subpool lock should be locked with spin_lock_irq() and all call sites was
modified as such, except for the ones in hugetlbfs_statfs().

Link: https://lkml.kernel.org/r/20220429202207.3045-1-almasrymina@google.com
Fixes: db71ef79 ("hugetlb: make free_huge_page irq safe")
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/hugetlbfs/inode.c

@@ -1048,12 +1048,12 @@ static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 		if (sbinfo->spool) {
 			long free_pages;
 
-			spin_lock(&sbinfo->spool->lock);
+			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;
-			spin_unlock(&sbinfo->spool->lock);
+			spin_unlock_irq(&sbinfo->spool->lock);
 			buf->f_files = sbinfo->max_inodes;
 			buf->f_ffree = sbinfo->free_inodes;
 		}