From 39fec6889d15a658c3a3ebb06fd69d3584ddffd3 Mon Sep 17 00:00:00 2001
From: Shaoying Xu <shaoyi@amazon.com>
Date: Thu, 2 Sep 2021 16:44:12 +0000
Subject: [PATCH] ext4: fix lazy initialization next schedule time computation
 in more granular unit
Git-commit: 39fec6889d15a658c3a3ebb06fd69d3584ddffd3
Patch-mainline: v5.16-rc1
References: bsc#1194580

Ext4 file system has default lazy inode table initialization setup once
it is mounted. However, it has issue on computing the next schedule time
that makes the timeout same amount in jiffies but different real time in
secs if with various HZ values. Therefore, fix by measuring the current
time in a more granular unit nanoseconds and make the next schedule time
independent of the HZ value.

Fixes: bfff68738f1c ("ext4: add support for lazy inode table initialization")
Signed-off-by: Shaoying Xu <shaoyi@amazon.com>
Cc: stable@vger.kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210902164412.9994-2-shaoyi@amazon.com
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/ext4/super.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2920,8 +2920,8 @@ static int ext4_run_li_request(struct ex
 	struct ext4_group_desc *gdp = NULL;
 	ext4_group_t group, ngroups;
 	struct super_block *sb;
-	unsigned long timeout = 0;
 	int ret = 0;
+	u64 start_time;
 
 	sb = elr->lr_super;
 	ngroups = EXT4_SB(sb)->s_groups_count;
@@ -2941,13 +2941,12 @@ static int ext4_run_li_request(struct ex
 		ret = 1;
 
 	if (!ret) {
-		timeout = jiffies;
+		start_time = ktime_get_real_ns();
 		ret = ext4_init_inode_table(sb, group,
 					    elr->lr_timeout ? 0 : 1);
 		if (elr->lr_timeout == 0) {
-			timeout = (jiffies - timeout) *
-				  elr->lr_sbi->s_li_wait_mult;
-			elr->lr_timeout = timeout;
+			elr->lr_timeout = nsecs_to_jiffies((ktime_get_real_ns() - start_time) *
+				EXT4_SB(elr->lr_super)->s_li_wait_mult);
 		}
 		elr->lr_next_sched = jiffies + elr->lr_timeout;
 		elr->lr_next_group = group + 1;