Re: [PATCH -next v3] jbd2: Fix data missing when reusing bh which is ready to be checkpointed

[Zhihao Cheng]

> On Mon 09-01-23 21:45:45, Zhihao Cheng wrote >> Following process will make data lost and could lead to a 
filesystem>> corrupted problem:>>
[...]

> Just a suggestion for rephrasing of the comment below
>
> > -		/*
> > -		 * In any case we need to clean the dirty flag and we must
> > -		 * do it under the buffer lock to be sure we don't race
> > -		 * with running write-out.
> > +		 * We need to clean the dirty flag and we must do it under the
> > +		 * buffer lock to be sure we don't race with running write-out.
> >   		 */
> >   		JBUFFER_TRACE(jh, "Journalling dirty buffer");
> >   		clear_buffer_dirty(bh);
> > +		/*
> > +		 * Setting jbddirty after clearing buffer dirty is necessary.
> > +		 * Function jbd2_journal_restart() could keep buffer on
> > +		 * BJ_Reserved list until the transaction committing, then the
> > +		 * buffer won't be dirtied by jbd2_journal_refile_buffer()
> > +		 * after committing, the buffer couldn't fall on disk even
> > +		 * last checkpoint finished, which may corrupt filesystem.
> > +		 */
>
> As far as I understand you want to say:
> 		/*
> 		 * The buffer is going to be added to BJ_Reserved list now
> 		 * and nothing guarantees jbd2_journal_dirty_metadata()
> 		 * will be ever called for it. So we need to set jbddirty
> 		 * bit here to make sure the buffer is dirtied and written
> 		 * out when the journaling machinery is done with it.
> 		 */
>
> >   		set_buffer_jbddirty(bh);
> >   	}

Yes. The comment looks better than v3.