On 7/21/20 4:35 PM, Guoqing Jiang wrote:
>
>
> On 7/20/20 8:08 PM, Zhao Heming wrote:
>> When array convert to clustered bitmap, the safe_mode_delay doesn't
>> clean and vice versa. the /sys/block/mdX/md/safe_mode_delay keep original
>> value after changing bitmap type. In safe_delay_store(), the code forbids
>> setting mddev->safemode_delay when array is clustered. So in cluster-md
>> env, the expected safemode_delay value should be 0.
>>
>> Reproducible steps:
>> ```
>> node1 # mdadm --zero-superblock /dev/sd{b,c,d}
>> node1 # mdadm -C /dev/md0 -b internal -e 1.2 -n 2 -l mirror /dev/sdb /dev/sdc
>> node1 # cat /sys/block/md0/md/safe_mode_delay
>> 0.204
>> node1 # mdadm -G /dev/md0 -b none
>> node1 # mdadm --grow /dev/md0 --bitmap=clustered
>> node1 # cat /sys/block/md0/md/safe_mode_delay
>> 0.204 <== doesn't change, should ZERO for cluster-md
>>
>> node1 # mdadm --zero-superblock /dev/sd{b,c,d}
>> node1 # mdadm -C /dev/md0 -b clustered -e 1.2 -n 2 -l mirror /dev/sdb /dev/sdc
>> node1 # cat /sys/block/md0/md/safe_mode_delay
>> 0.000
>> node1 # mdadm -G /dev/md0 -b none
>> node1 # cat /sys/block/md0/md/safe_mode_delay
>> 0.000 <== doesn't change, should default value
>> ```
>>
>> Signed-off-by: Zhao Heming <heming.zhao@xxxxxxxx>
>> ---
>> drivers/md/md.c | 11 +++++++++--
>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index f567f536b529..1bde3df3fa18 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -101,6 +101,8 @@ static void mddev_detach(struct mddev *mddev);
>> * count by 2 for every hour elapsed between read errors.
>> */
>> #define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
>> +/* Default safemode delay: 200 msec */
>> +#define DEFAULT_SAFEMODE_DELAY ((200 * HZ)/1000 +1)
>> /*
>> * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
>> * is 1000 KB/sec, so the extra system load does not show up that much.
>> @@ -5982,7 +5984,7 @@ int md_run(struct mddev *mddev)
>> if (mddev_is_clustered(mddev))
>> mddev->safemode_delay = 0;
>> else
>> - mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
>> + mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
>> mddev->in_sync = 1;
>> smp_wmb();
>> spin_lock(&mddev->lock);
>> @@ -7361,6 +7363,7 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
>> mddev->bitmap_info.nodes = 0;
>> md_cluster_ops->leave(mddev);
>> + mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
>> }
>
> Not about the patch itself, just confuse about the meaning of safemode_delay.
> As safemode_delay represents 200 ms delay, but md_write_end has this.
>
> /* The roundup() ensures this only performs locking once
> * every ->safemode_delay *jiffies*
> */
> mod_timer(&mddev->safemode_timer,
> roundup(jiffies, mddev->safemode_delay) +
> mddev->safemode_delay);
>
> And the second argument in mod_timer() means "new timeout in jiffies",
> does the above need to convert from ms to jiffies? Am I miss something?
>
> Thanks,
> Guoqing
>
The safemode_delay stores jiffies not msec. it converts to ms only in safe_delay_{store|show}.
please see default value:
#define DEFAULT_SAFEMODE_DELAY ((200 * HZ)/1000 +1)
in safe_delay_store, user space input will multiple 10^3, which will convert from second to msec.
then (*HZ/1000) to jiffies.
