Revert "f2fs: fix to set flush_merge opt and show noflush_merge"

This reverts commit 6ba0594 which is
commit 967eaad upstream.

Something is currently broken in the f2fs code, Guenter has reported
boot problems with it for a few releases now, so revert the most recent
f2fs changes in the hope to get this back to a working filesystem.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/b392e1a8-b987-4993-bd45-035db9415a6e@roeck-us.net
Cc: Chao Yu <chao@kernel.org>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Yangtao Li <frank.li@vivo.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/f2fs/super.c

@@ -1347,12 +1347,6 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
 		return -EINVAL;
 	}
 
-	if ((f2fs_sb_has_readonly(sbi) || f2fs_readonly(sbi->sb)) &&
-		test_opt(sbi, FLUSH_MERGE)) {
-		f2fs_err(sbi, "FLUSH_MERGE not compatible with readonly mode");
-		return -EINVAL;
-	}
-
 	if (f2fs_sb_has_readonly(sbi) && !f2fs_readonly(sbi->sb)) {
 		f2fs_err(sbi, "Allow to mount readonly mode only");
 		return -EROFS;
@@ -1939,10 +1933,8 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
 		seq_puts(seq, ",inline_dentry");
 	else
 		seq_puts(seq, ",noinline_dentry");
-	if (test_opt(sbi, FLUSH_MERGE))
+	if (!f2fs_readonly(sbi->sb) && test_opt(sbi, FLUSH_MERGE))
 		seq_puts(seq, ",flush_merge");
-	else
-		seq_puts(seq, ",noflush_merge");
 	if (test_opt(sbi, NOBARRIER))
 		seq_puts(seq, ",nobarrier");
 	if (test_opt(sbi, FASTBOOT))
@@ -2071,8 +2063,7 @@ static void default_options(struct f2fs_sb_info *sbi)
 	set_opt(sbi, MERGE_CHECKPOINT);
 	F2FS_OPTION(sbi).unusable_cap = 0;
 	sbi->sb->s_flags |= SB_LAZYTIME;
-	if (!f2fs_sb_has_readonly(sbi) && !f2fs_readonly(sbi->sb))
-		set_opt(sbi, FLUSH_MERGE);
+	set_opt(sbi, FLUSH_MERGE);
 	if (f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi))
 		set_opt(sbi, DISCARD);
 	if (f2fs_sb_has_blkzoned(sbi)) {