f2fs: convert to use sysfs_emit

Let's use sysfs_emit.
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/sysfs.c

@@ -312,19 +312,14 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
 
 	if (!strcmp(a->attr.name, "ckpt_thread_ioprio")) {
 		struct ckpt_req_control *cprc = &sbi->cprc_info;
-		int len = 0;
 		int class = IOPRIO_PRIO_CLASS(cprc->ckpt_thread_ioprio);
 		int data = IOPRIO_PRIO_DATA(cprc->ckpt_thread_ioprio);
 
-		if (class == IOPRIO_CLASS_RT)
-			len += scnprintf(buf + len, PAGE_SIZE - len, "rt,");
-		else if (class == IOPRIO_CLASS_BE)
-			len += scnprintf(buf + len, PAGE_SIZE - len, "be,");
-		else
+		if (class != IOPRIO_CLASS_RT && class != IOPRIO_CLASS_BE)
 			return -EINVAL;
 
-		len += scnprintf(buf + len, PAGE_SIZE - len, "%d\n", data);
-		return len;
+		return sysfs_emit(buf, "%s,%d\n",
+			class == IOPRIO_CLASS_RT ? "rt" : "be", data);
 	}
 
 #ifdef CONFIG_F2FS_FS_COMPRESSION