Comment # 10 on bug 1231836 from Wenruo Qu

(In reply to Wenruo Qu from comment #9)
> BTW, I also explored another solution, to allow mismatch in sb->s_flags and
> fc->sb_flags, then reconfigure.
> This methods avoid the brute force retry loop, and use proper rwsem to
> prevent race in theory.
> 
> But it just doesn't work.
> 
> If the fs is initially mounted RO, a new RW open on the same device will
> return -EINVAL, thus rejecting the mount way earlier before we can get a
> proper super block to continue.
> 
> That's why we're risking the race by retry without a proper sb lock to hold.

What an idiot I am, I'm using a wrong script to test, thus mounting a wrong
device, no wonder device scan failed, it's not related to the flag.

I'll do more testing to make sure if we can go the new solution.