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ext4: fix lazy initialization next schedule time computation in more granular unit

PATCH In review Shaoying Xu 2 participants 4 messages Nov 15, 2021 – Nov 18, 2021 Stable branch

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Shaoying Xu

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#0 lore raw

PATCH 1/1 ext4: fix lazy initialization next schedule time computation in more granular unit

commit 39fec6889d15a658c3a3ebb06fd69d3584ddffd3 upstream.

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 <[email protected]>
Cc [email protected]
Signed-off-by Theodore Ts'o <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Theodore Ts'o <[email protected]>

---
Member lr_sbi was removed from the struct ext4_li_request since kernel 5.9 so the way to access s_li_wait_mult was also changed. To adapt to the old kernel versions, adjust the upstream fix by following the old ext4_li_request strucutre.

 fs/ext4/super.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)
fs/ext4/super.c +4 -5
index 1211ae203fac..f68dfef5939f 100644
@@ -3071,8 +3071,8 @@ static int ext4_run_li_request(struct ext4_li_request *elr)
 	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;

@@ -3092,13 +3092,12 @@ static int ext4_run_li_request(struct ext4_li_request *elr)
 		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) *
+				  elr->lr_sbi->s_li_wait_mult);
 		}
 		elr->lr_next_sched = jiffies + elr->lr_timeout;
 		elr->lr_next_group = group + 1;
Signature · 1 line
2.16.6
#1 lore raw
Quoted 15 lines · Shaoying Xu

commit 39fec6889d15a658c3a3ebb06fd69d3584ddffd3 upstream.

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 <[email protected]>
Cc [email protected]
Signed-off-by Theodore Ts'o <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Theodore Ts'o <[email protected]>
Quoted 5 lines

---
Member lr_sbi was removed from the struct ext4_li_request since kernel 5.9 so the way to access s_li_wait_mult was also changed. To adapt to the old kernel versions, adjust the upstream fix by following the old ext4_li_request strucutre.

Now queued up, thanks.

greg k-h

author
#2 lore raw

Thank you! Can the patch also be added to kernel 4.19 and 4.14 please?

Quoted 29 lines · Greg KH

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Quoted 15 lines · Shaoying Xu

commit 39fec6889d15a658c3a3ebb06fd69d3584ddffd3 upstream.

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 <[email protected]>
Cc [email protected]
Signed-off-by Theodore Ts'o <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Theodore Ts'o <[email protected]>
Quoted 5 lines

---
Member lr_sbi was removed from the struct ext4_li_request since kernel 5.9 so the way to access s_li_wait_mult was also changed. To adapt to the old kernel versions, adjust the upstream fix by following the old ext4_li_request strucutre.

Now queued up, thanks.

greg k-h

#3 lore raw
Quoted 1 line · Shaoying Xu

Thank you! Can the patch also be added to kernel 4.19 and 4.14 please?

Now queued up, thanks.

greg k-h