Re: [PATCH 1/3] quota: Check next/prev free block number after reading from quota file

[Zhihao Cheng]

在 2022/9/22 19:39, Jan Kara 写道:
> On Thu 22-09-22 16:13:59, Zhihao Cheng wrote:
[...]
> > > The free block should actually be > QT_TREEOFF so I'd add the check to
> > > do_check_range().
> >
> > 'dh->dqdh_next_free' may be updated when quota entry removed,
> > 'dh->dqdh_next_free' can be used for next new quota entris.
> > Before sending v2, I found 'dh->dqdh_next_free' and 'dh->dqdh_prev_free' can
> > easily be zero in newly allocated blocks when continually creating files
> > onwed by different users:
> > find_free_dqentry
> >    get_free_dqblk
> >      write_blk(info, info->dqi_blocks, buf)  // zero'd qt_disk_dqdbheader
> >      blk = info->dqi_blocks++   // allocate new one block
> >    info->dqi_free_entry = blk   // will be used for new quota entries
> >
> > find_free_dqentry
> >    if (info->dqi_free_entry)
> >      blk = info->dqi_free_entry
> >      read_blk(info, blk, buf)   // dh->dqdh_next_free = dh->dqdh_prev_free =
> > 0
> >
> > I think it's normal when 'dh->dqdh_next_free' or 'dh->dqdh_prev_free' equals
> > to 0.
>
> Good point! 0 means "not present". So any block number (either in free list
> or pointed from the quota tree) should be either 0 or > QT_TREEOFF.
>
> 								Honza

In case my emails being filtered agagin, this is notification of v2:
https://lore.kernel.org/linux-ext4/20220922130401.1792256-1-chengzhihao1@xxxxxxxxxx/T/#m9676d64e8f7cdd7b7decdd0d6b725ec658110b3e