Messages in this thread | | | From | Xiao Ni <> | Date | Wed, 13 Oct 2021 15:57:57 +0800 | Subject | Re: [PATCH RESEND] md: allow to set the fail_fast on RAID1/RAID10 |
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On Tue, Oct 12, 2021 at 5:14 PM Li Feng <fengli@smartx.com> wrote: > > sysfs_notify_dirent_safe(rdev->sysfs_state); > > + if (need_update_sb) > > + if (mddev->pers) { > > + set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags); > > + md_wakeup_thread(mddev->thread); > > + } > When will mddev->pers is NULL?
The process of creating a raid device is: 1. md_ioctl->md_add_new_disk 2. md_ioctl->do_md_run->md_run->(pers->run)->(mddev->pers = pers) In md_add_new_disk it creates the per device sysfs files. It can read/write these files before setting mddev->pers.
> If it is NULL, this change will not on disk.
I did a test. You are right. Someone can change the per device state before ADD_NEW_DISK and RUN_ARRAY ioctl. Please note, the mdadm --create command doesn't return until RUN_ARRAY ioctl finishes. Even though the are small, we can try to set MD_SB_CHANGE_DEVS.
Best regards Xiao
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