erofs: make erofs_{err,info}() support NULL sb parameter

Make erofs_err() and erofs_info() support NULL sb parameter for more
general usage.
Suggested-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Link: https://lore.kernel.org/r/20240103123202.3054718-1-guochunhai@vivo.comReviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/decompressor_deflate.c

@@ -70,7 +70,7 @@ int __init z_erofs_deflate_init(void)
 	return 0;
 
 out_failed:
-	pr_err("failed to allocate zlib workspace\n");
+	erofs_err(NULL, "failed to allocate zlib workspace");
 	z_erofs_deflate_exit();
 	return -ENOMEM;
 }

fs/erofs/super.c

@@ -27,7 +27,10 @@ void _erofs_err(struct super_block *sb, const char *func, const char *fmt, ...)
 	vaf.fmt = fmt;
 	vaf.va = &args;
 
-	pr_err("(device %s): %s: %pV", sb->s_id, func, &vaf);
+	if (sb)
+		pr_err("(device %s): %s: %pV", sb->s_id, func, &vaf);
+	else
+		pr_err("%s: %pV", func, &vaf);
 	va_end(args);
 }
 
@@ -41,7 +44,10 @@ void _erofs_info(struct super_block *sb, const char *func, const char *fmt, ...)
 	vaf.fmt = fmt;
 	vaf.va = &args;
 
-	pr_info("(device %s): %pV", sb->s_id, &vaf);
+	if (sb)
+		pr_info("(device %s): %pV", sb->s_id, &vaf);
+	else
+		pr_info("%pV", &vaf);
 	va_end(args);
 }