erofs: derive fsid from on-disk UUID for .statfs() if possible

Use the superblock's UUID to generate the fsid when it's non-null.

Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240409113022.74720-1-hongzhen@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index c1dae1fb949b2d3caa6a9b67fecde90bd761c3e1..e3438f1a7bacda47458a1d7879d4c453eee3168f 100644 (file)
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -914,22 +914,20 @@ static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
        struct super_block *sb = dentry->d_sb;
        struct erofs_sb_info *sbi = EROFS_SB(sb);
-       u64 id = 0;
-
-       if (!erofs_is_fscache_mode(sb))
-               id = huge_encode_dev(sb->s_bdev->bd_dev);
 
        buf->f_type = sb->s_magic;
        buf->f_bsize = sb->s_blocksize;
        buf->f_blocks = sbi->total_blocks;
        buf->f_bfree = buf->f_bavail = 0;
-
        buf->f_files = ULLONG_MAX;
        buf->f_ffree = ULLONG_MAX - sbi->inos;
-
        buf->f_namelen = EROFS_NAME_LEN;
 
-       buf->f_fsid    = u64_to_fsid(id);
+       if (uuid_is_null(&sb->s_uuid))
+               buf->f_fsid = u64_to_fsid(erofs_is_fscache_mode(sb) ? 0 :
+                               huge_encode_dev(sb->s_bdev->bd_dev));
+       else
+               buf->f_fsid = uuid_to_fsid(sb->s_uuid.b);
        return 0;
 }