On Sat 11-09-21 17:00:59, Ye Bin wrote: > Test follow steps: > 1. mkfs.ext4 /dev/sda -O mmp > 2. mount /dev/sda /mnt > 3. wait for about 1 minute > 4. umount mnt > 5. debugfs /dev/sda > 6. dump_mmp > 7. fsck.ext4 /dev/sda > > I found 'check_interval' is range in [5, 10]. And sometime run fsck > print "MMP interval is 10 seconds and total wait time is 42 seconds. > Please wait...". > kmmpd: > ... > if (diff < mmp_update_interval * HZ) > schedule_timeout_interruptible(mmp_update_interval * HZ - diff); > diff = jiffies - last_update_time; > ... > mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff / HZ, > EXT4_MMP_MAX_CHECK_INTERVAL), > EXT4_MMP_MIN_CHECK_INTERVAL); > mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval); > ... > We will call ext4_stop_mmpd to stop kmmpd kthread when umount, and > schedule_timeout_interruptible will be interrupted, so 'diff' maybe > little than mmp_update_interval. Then mmp_check_interval will range > in [EXT4_MMP_MAX_CHECK_INTERVAL, EXT4_MMP_CHECK_MULT * diff / HZ]. > To solve this issue, if 'diff' little then mmp_update_interval * HZ > just break loop, don't update check interval. > > Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx> > --- > fs/ext4/mmp.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c > index a0d47a906faa..f39e1fa0c6db 100644 > --- a/fs/ext4/mmp.c > +++ b/fs/ext4/mmp.c > @@ -205,6 +205,14 @@ static int kmmpd(void *data) > schedule_timeout_interruptible(mmp_update_interval * > HZ - diff); > diff = jiffies - last_update_time; > + /* If 'diff' little 'than mmp_update_interval * HZ', it > + * means someone call ext4_stop_mmpd to stop kmmpd > + * kthread. We don't need to update mmp_check_interval > + * any more, as 'diff' is not exact value. > + */ > + if (unlikely(diff < mmp_update_interval * HZ && > + kthread_should_stop())) > + break; > } So in this case, mmp_check_interval would be EXT4_MMP_MIN_CHECK_INTERVAL. I don't quite understand what the practical problem is - the fsck message? That will happen anytime mmp_check_interval is >= 10 AFAICT and I don't quite see how that is connected to this condition... Can you explain a bit more please? Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
