Ocfs2 devel - Jun 2013 - ocfs2: Should move ocfs2_start_trans out of lock_page

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

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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