2024-05-07 02:41:26

by Li Nan

Subject: [PATCH] md: Revert "md: Fix overflow in is_mddev_idle"

From: Li Nan <[email protected]>

This reverts commit 3f9f231236ce7e48780d8a4f1f8cb9fae2df1e4e.

Using 64bit for 'sync_io' is unnecessary from the gendisk side. This
overflow will not cause any functional impact, except for a UBSAN
warning. Solving this overflow requires introducing additional
calculations and checks which are not necessary. So just keep using
32bit for 'sync_io'.

Signed-off-by: Li Nan <[email protected]>
---
drivers/md/md.h | 4 ++--
include/linux/blkdev.h | 2 +-
drivers/md/md.c | 7 +++----
3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 029dd0491a36..ca085ecad504 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -51,7 +51,7 @@ struct md_rdev {

sector_t sectors; /* Device size (in 512bytes sectors) */
struct mddev *mddev; /* RAID array if running */
- long long last_events; /* IO event timestamp */
+ int last_events; /* IO event timestamp */

/*
* If meta_bdev is non-NULL, it means that a separate device is
@@ -622,7 +622,7 @@ extern void mddev_unlock(struct mddev *mddev);
static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
{
if (blk_queue_io_stat(bdev->bd_disk->queue))
- atomic64_add(nr_sectors, &bdev->bd_disk->sync_io);
+ atomic_add(nr_sectors, &bdev->bd_disk->sync_io);
}

static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c854d5a6a6fe..41e995ce4bff 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -174,7 +174,7 @@ struct gendisk {
struct list_head slave_bdevs;
#endif
struct timer_rand_state *random;
- atomic64_t sync_io; /* RAID */
+ atomic_t sync_io; /* RAID */
struct disk_events *ev;

#ifdef CONFIG_BLK_DEV_ZONED
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 00bbafcd27bb..aff9118ff697 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8577,7 +8577,7 @@ static int is_mddev_idle(struct mddev *mddev, int init)
{
struct md_rdev *rdev;
int idle;
- long long curr_events;
+ int curr_events;

idle = 1;
rcu_read_lock();
@@ -8587,9 +8587,8 @@ static int is_mddev_idle(struct mddev *mddev, int init)
if (!init && !blk_queue_io_stat(disk->queue))
continue;

- curr_events =
- (long long)part_stat_read_accum(disk->part0, sectors) -
- atomic64_read(&disk->sync_io);
+ curr_events = (int)part_stat_read_accum(disk->part0, sectors) -
+ atomic_read(&disk->sync_io);
/* sync IO will cause sync_io to increase before the disk_stats
* as sync_io is counted when a request starts, and
* disk_stats is counted when it completes.
--
2.39.2

2024-05-07 13:47:56

by Jens Axboe

Subject: Re: [PATCH] md: Revert "md: Fix overflow in is_mddev_idle"

On Tue, 07 May 2024 10:31:03 +0800, [email protected] wrote:
> This reverts commit 3f9f231236ce7e48780d8a4f1f8cb9fae2df1e4e.
>
> Using 64bit for 'sync_io' is unnecessary from the gendisk side. This
> overflow will not cause any functional impact, except for a UBSAN
> warning. Solving this overflow requires introducing additional
> calculations and checks which are not necessary. So just keep using
> 32bit for 'sync_io'.
>
> [...]

Applied, thanks!

[1/1] md: Revert "md: Fix overflow in is_mddev_idle"
commit: 504fbcffea649cad69111e7597081dd8adc3b395

Best regards,
--
Jens Axboe