f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

No need to call f2fs_issue_discard_timeout() in f2fs_put_super,
when no discard command requires issue. Since the caller of
f2fs_issue_discard_timeout() usually judges the number of discard
commands before using it. Let's move this logic to
f2fs_issue_discard_timeout().

By the way, use f2fs_realtime_discard_enable to simplify the code.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -1661,6 +1661,9 @@ bool f2fs_issue_discard_timeout(struct f2fs_sb_info *sbi)
 	struct discard_policy dpolicy;
 	bool dropped;
 
+	if (!atomic_read(&dcc->discard_cmd_cnt))
+		return false;
+
 	__init_discard_policy(sbi, &dpolicy, DPOLICY_UMOUNT,
 					dcc->discard_granularity);
 	__issue_discard_cmd(sbi, &dpolicy);
@@ -2116,8 +2119,7 @@ static void destroy_discard_cmd_control(struct f2fs_sb_info *sbi)
 	 * Recovery can cache discard commands, so in error path of
 	 * fill_super(), it needs to give a chance to handle them.
 	 */
-	if (unlikely(atomic_read(&dcc->discard_cmd_cnt)))
-		f2fs_issue_discard_timeout(sbi);
+	f2fs_issue_discard_timeout(sbi);
 
 	kfree(dcc);
 	SM_I(sbi)->dcc_info = NULL;

fs/f2fs/super.c

@@ -1581,8 +1581,7 @@ static void f2fs_put_super(struct super_block *sb)
 	/* be sure to wait for any on-going discard commands */
 	dropped = f2fs_issue_discard_timeout(sbi);
 
-	if ((f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) &&
-					!sbi->discard_blks && !dropped) {
+	if (f2fs_realtime_discard_enable(sbi) && !sbi->discard_blks && !dropped) {
 		struct cp_control cpc = {
 			.reason = CP_UMOUNT | CP_TRIMMED,
 		};
@@ -2233,7 +2232,6 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	bool no_discard = !test_opt(sbi, DISCARD);
 	bool no_compress_cache = !test_opt(sbi, COMPRESS_CACHE);
 	bool block_unit_discard = f2fs_block_unit_discard(sbi);
-	struct discard_cmd_control *dcc;
 #ifdef CONFIG_QUOTA
 	int i, j;
 #endif
@@ -2420,10 +2418,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 				goto restore_flush;
 			need_stop_discard = true;
 		} else {
-			dcc = SM_I(sbi)->dcc_info;
 			f2fs_stop_discard_thread(sbi);
-			if (atomic_read(&dcc->discard_cmd_cnt))
-				f2fs_issue_discard_timeout(sbi);
+			f2fs_issue_discard_timeout(sbi);
 			need_restart_discard = true;
 		}
 	}