linux-kernel - [PATCH] f2fs: init discard policy after thread wakeup

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Date:   Fri, 18 Nov 2022 11:46:00 +0800
From:   Yangtao Li <frank.li@...o.com>
To:     jaegeuk@...nel.org, chao@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Yangtao Li <frank.li@...o.com>
Subject: [PATCH] f2fs: init discard policy after thread wakeup

Under the current logic, after the discard thread wakes up, it will not
run according to the expected policy, but will use the expected policy
before sleep. Move the strategy selection to after the thread wakes up,
so that the running state of the thread meets expectations.

Signed-off-by: Yangtao Li <frank.li@...o.com>
---
 fs/f2fs/segment.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8b0b76550578..609e90aa80c2 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1685,6 +1685,11 @@ static int issue_discard_thread(void *data)
 	set_freezable();
 
 	do {
+		wait_event_interruptible_timeout(*q,
+				kthread_should_stop() || freezing(current) ||
+				dcc->discard_wake,
+				msecs_to_jiffies(wait_ms));
+
 		if (sbi->gc_mode == GC_URGENT_HIGH ||
 			!f2fs_available_free_memory(sbi, DISCARD_CACHE))
 			__init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);
@@ -1692,14 +1697,6 @@ static int issue_discard_thread(void *data)
 			__init_discard_policy(sbi, &dpolicy, DPOLICY_BG,
 						dcc->discard_granularity);
 
-		if (!atomic_read(&dcc->discard_cmd_cnt))
-		       wait_ms = dpolicy.max_interval;
-
-		wait_event_interruptible_timeout(*q,
-				kthread_should_stop() || freezing(current) ||
-				dcc->discard_wake,
-				msecs_to_jiffies(wait_ms));
-
 		if (dcc->discard_wake)
 			dcc->discard_wake = 0;
 
@@ -1713,12 +1710,11 @@ static int issue_discard_thread(void *data)
 			continue;
 		if (kthread_should_stop())
 			return 0;
-		if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) {
+		if (is_sbi_flag_set(sbi, SBI_NEED_FSCK) ||
+			!atomic_read(&dcc->discard_cmd_cnt)) {
 			wait_ms = dpolicy.max_interval;
 			continue;
 		}
-		if (!atomic_read(&dcc->discard_cmd_cnt))
-			continue;
 
 		sb_start_intwrite(sbi->sb);
 
@@ -1733,6 +1729,8 @@ static int issue_discard_thread(void *data)
 		} else {
 			wait_ms = dpolicy.max_interval;
 		}
+		if (!atomic_read(&dcc->discard_cmd_cnt))
+			wait_ms = dpolicy.max_interval;
 
 		sb_end_intwrite(sbi->sb);
 
-- 
2.25.1