f2fs: fix to propagate error from f2fs_enable_checkpoint()

In order to let userspace detect such error rather than suffering
silent failure.

Fixes: 4354994 ("f2fs: checkpoint disabling")
Cc: stable@kernel.org
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: chaseyu

fs/f2fs/super.c

@@ -2632,10 +2632,11 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
 	return err;
 }
 
-static void f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
+static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 {
 	unsigned int nr_pages = get_pages(sbi, F2FS_DIRTY_DATA) / 16;
 	long long start, writeback, end;
+	int ret;
 
 	f2fs_info(sbi, "f2fs_enable_checkpoint() starts, meta: %lld, node: %lld, data: %lld",
 					get_pages(sbi, F2FS_DIRTY_META),
@@ -2669,7 +2670,9 @@ static void f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 	set_sbi_flag(sbi, SBI_IS_DIRTY);
 	f2fs_up_write(&sbi->gc_lock);
 
-	f2fs_sync_fs(sbi->sb, 1);
+	ret = f2fs_sync_fs(sbi->sb, 1);
+	if (ret)
+		f2fs_err(sbi, "%s sync_fs failed, ret: %d", __func__, ret);
 
 	/* Let's ensure there's no pending checkpoint anymore */
 	f2fs_flush_ckpt_thread(sbi);
@@ -2679,6 +2682,7 @@ static void f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
 	f2fs_info(sbi, "f2fs_enable_checkpoint() finishes, writeback:%llu, sync:%llu",
 					ktime_ms_delta(writeback, start),
 					ktime_ms_delta(end, writeback));
+	return ret;
 }
 
 static int __f2fs_remount(struct fs_context *fc, struct super_block *sb)
@@ -2892,7 +2896,9 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb)
 				goto restore_discard;
 			need_enable_checkpoint = true;
 		} else {
-			f2fs_enable_checkpoint(sbi);
+			err = f2fs_enable_checkpoint(sbi);
+			if (err)
+				goto restore_discard;
 			need_disable_checkpoint = true;
 		}
 	}
@@ -2935,7 +2941,8 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb)
 	return 0;
 restore_checkpoint:
 	if (need_enable_checkpoint) {
-		f2fs_enable_checkpoint(sbi);
+		if (f2fs_enable_checkpoint(sbi))
+			f2fs_warn(sbi, "checkpoint has not been enabled");
 	} else if (need_disable_checkpoint) {
 		if (f2fs_disable_checkpoint(sbi))
 			f2fs_warn(sbi, "checkpoint has not been disabled");
@@ -5212,13 +5219,12 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (err)
 		goto sync_free_meta;
 
-	if (test_opt(sbi, DISABLE_CHECKPOINT)) {
+	if (test_opt(sbi, DISABLE_CHECKPOINT))
 		err = f2fs_disable_checkpoint(sbi);
-		if (err)
-			goto sync_free_meta;
-	} else if (is_set_ckpt_flags(sbi, CP_DISABLED_FLAG)) {
-		f2fs_enable_checkpoint(sbi);
-	}
+	else if (is_set_ckpt_flags(sbi, CP_DISABLED_FLAG))
+		err = f2fs_enable_checkpoint(sbi);
+	if (err)
+		goto sync_free_meta;
 
 	/*
 	 * If filesystem is not mounted as read-only then