[Ocfs2-devel] ocfs2: Should move ocfs2_start_trans out of lock_page

[Joel Becker]

I'm pretty sure we did it for a reason, which means we need to think
about it more than just looking at ext4.  Remember that we get access
coming from other node actions.

Joel

On Mon, Jun 24, 2013 at 04:55:20PM +0800, Joseph Qi wrote:
> Any different opinion?
> 
> On 2013/6/19 16:17, Joseph Qi wrote:
> > Currently ocfs2_start_trans/ocfs2_commit_trans are in
> > lock_page/unlock_page. This may cause dead lock.
> > 
> > Here is the situation:
> > write -> lock_page -> ocfs2_start_trans -> ocfs2_commit_trans -> unlock_page
> > ocfs2_start_trans/ocfs2_commit_trans calls
> > jbd2_journal_start/jbd2_journal_stop which may also call lock_page. So
> > if the page operated is unfortunately the same with the page to be
> > committed, dead lock happens.
> > 
> > In ext4, lock_page/unlock_page are in
> > ext4_journal_start/ext4_journal_stop, this can avoid such kind of dead
> > lock. So I think we should move ocfs2_start_trans/ocfs2_commit_trans out
> > of lock_page/unlock_page.
> > 
> > Totally there are 5 related functions:
> > ocfs2_write_begin_nolock
> > ocfs2_write_begin_inline
> > ocfs2_write_end_nolock
> > ocfs2_write_zero_page
> > ocfs2_convert_inline_data_to_extents
> > 
> > 
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> > 
> > 
> 
> 
> 
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