erofs: move packed inode out of the compression part

packed inode could be used in more scenarios which are independent of
compression in the future.

For example, packed inode could be used to keep extra long xattr
prefixes with the help of following patches.
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Acked-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230407141710.113882-4-jefflexu@linux.alibaba.comSigned-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/internal.h

@@ -134,8 +134,8 @@ struct erofs_sb_info {
 	struct inode *managed_cache;
 
 	struct erofs_sb_lz4_info lz4;
-	struct inode *packed_inode;
 #endif	/* CONFIG_EROFS_FS_ZIP */
+	struct inode *packed_inode;
 	struct erofs_dev_context *devs;
 	struct dax_device *dax_dev;
 	u64 dax_part_off;

fs/erofs/super.c

@@ -808,7 +808,6 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	erofs_shrinker_register(sb);
 	/* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
-#ifdef CONFIG_EROFS_FS_ZIP
 	if (erofs_sb_has_fragments(sbi) && sbi->packed_nid) {
 		sbi->packed_inode = erofs_iget(sb, sbi->packed_nid);
 		if (IS_ERR(sbi->packed_inode)) {
@@ -817,7 +816,6 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 			return err;
 		}
 	}
-#endif
 	err = erofs_init_managed_cache(sb);
 	if (err)
 		return err;
@@ -984,9 +982,9 @@ static void erofs_put_super(struct super_block *sb)
 #ifdef CONFIG_EROFS_FS_ZIP
 	iput(sbi->managed_cache);
 	sbi->managed_cache = NULL;
+#endif
 	iput(sbi->packed_inode);
 	sbi->packed_inode = NULL;
-#endif
 	erofs_free_dev_context(sbi->devs);
 	sbi->devs = NULL;
 	erofs_fscache_unregister_fs(sb);