[PATCH 1/2] f2fs: Constrain the modification range of dir_level in the sysfs

[Yongpeng Yang]

The {struct f2fs_sb_info}->dir_level can be modified through the sysfs
interface, but its value range is not limited. If the value exceeds
MAX_DIR_HASH_DEPTH and the mount options include "noinline_dentry",
the following error will occur:
[root@fedora ~]# mount -o noinline_dentry /dev/sdb  /mnt/sdb/
[root@fedora ~]# echo 128 > /sys/fs/f2fs/sdb/dir_level
[root@fedora ~]# cd /mnt/sdb/
[root@fedora sdb]# mkdir test
[root@fedora sdb]# cd test/
[root@fedora test]# mkdir test
mkdir: cannot create directory 'test': Argument list too long

Signed-off-by: Yongpeng Yang <yangyongpeng1@xxxxxxxx>
---
 fs/f2fs/sysfs.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 7099ffa57299..8c8424b05fc7 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -741,6 +741,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}
 
+	if (!strcmp(a->attr.name, "dir_level")) {
+		if (t > MAX_DIR_HASH_DEPTH)
+			return -EINVAL;
+		sbi->dir_level = t;
+		return count;
+	}
+
 	*ui = (unsigned int)t;
 
 	return count;
-- 
2.40.1