fs/adfs: return f_fsid for statfs(2)

Currently many file systems in Linux kernel do not return f_fsid in statfs
info, the value is set as 0 in vfs layer.  Anyway, in some conditions,
f_fsid from statfs(2) is useful, especially being used as (f_fsid, ino)
pair to uniquely identify a file.

Basic idea of the patches is generating a unique fs ID by
huge_encode_dev(sb->s_bdev->bd_dev) during file system mounting life time
(no endian consistent issue).  sb is a point of struct super_block of
current mounted file system being accessed by statfs(2).

This patch:

Make adfs return f_fsid info for statfs(2), and do a little variable
renaming in adfs_statfs().

Signed-off-by: Coly Li <[email protected]>
Cc: Roman Zippel <[email protected]>
Cc: "Sergey S. Kostyliov" <[email protected]>
Cc: OGAWA Hirofumi <[email protected]>
Cc: Mikulas Patocka <[email protected]>
Cc: Dave Kleikamp <[email protected]>
Cc: Bob Copeland <[email protected]>
Cc: Anders Larsen <[email protected]>
Cc: Phillip Lougher <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Evgeniy Dushistov <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Jamie Lokier <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/adfs/super.c

@@ -219,16 +219,20 @@ static int adfs_remount(struct super_block *sb, int *flags, char *data)
 
 static int adfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
-	struct adfs_sb_info *asb = ADFS_SB(dentry->d_sb);
+	struct super_block *sb = dentry->d_sb;
+	struct adfs_sb_info *sbi = ADFS_SB(sb);
+	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 
 	buf->f_type    = ADFS_SUPER_MAGIC;
-	buf->f_namelen = asb->s_namelen;
-	buf->f_bsize   = dentry->d_sb->s_blocksize;
-	buf->f_blocks  = asb->s_size;
-	buf->f_files   = asb->s_ids_per_zone * asb->s_map_size;
+	buf->f_namelen = sbi->s_namelen;
+	buf->f_bsize   = sb->s_blocksize;
+	buf->f_blocks  = sbi->s_size;
+	buf->f_files   = sbi->s_ids_per_zone * sbi->s_map_size;
 	buf->f_bavail  =
-	buf->f_bfree   = adfs_map_free(dentry->d_sb);
+	buf->f_bfree   = adfs_map_free(sb);
 	buf->f_ffree   = (long)(buf->f_bfree * buf->f_files) / (long)buf->f_blocks;
+	buf->f_fsid.val[0] = (u32)id;
+	buf->f_fsid.val[1] = (u32)(id >> 32);
 
 	return 0;
 }