[Ocfs2-devel] [PATCH V2] ocfs2: call ocfs2_journal_access_di() before ocfs2_journal_dirty() in ocfs2_write_end_nolock()

[Wengang <wen.gang.wang@oracle.com>]

With this drop, you have to take care of the case of INLINE DATA.

thanks
wengang

? 2014?06?17? 19:50, yangwenfang ??:
> 1.After we call ocfs2_journal_access_di() in ocfs2_write_begin(),
> jbd2_journal_restart() may also be called, in this function
> transaction A's t_updates-- and obtains a new transaction B.
> If jbd2_journal_commit_transaction() is happened to commit
> transaction A, when t_updates==0, it will continue to complete
> commit and unfile buffer.
>
> So when jbd2_journal_dirty_metadata(), the handle is pointed a new
> transaction B, and the buffer head's journal head is already freed,
> jh->b_transaction == NULL, jh->b_next_transaction == NULL,
> it returns EINVAL, So it triggers the BUG_ON(status).
>
> thread 1:                             jbd2:
> ocfs2_write_begin                     jbd2_journal_commit_transaction
> ocfs2_write_begin_nolock
>    ocfs2_start_trans
>      jbd2__journal_start(t_updates+1,
>                         transaction A)
>      ocfs2_journal_access_di
>      ocfs2_write_cluster_by_desc
>        ocfs2_mark_extent_written
>          ocfs2_change_extent_flag
>            ocfs2_split_extent
>              ocfs2_extend_rotate_transaction
>                jbd2_journal_restart
>                (t_updates-1,transaction B) t_updates==0
>                                          __jbd2_journal_refile_buffer
>
> ocfs2_write_end
> ocfs2_write_end_nolock
>      ocfs2_journal_dirty
>          jbd2_journal_dirty_metadata(bug)
>     ocfs2_commit_trans
>
> 2. In ext4, I found that: jbd2_journal_get_write_access() called by
> ext4_write_end.
> ext4_write_begin
>      ext4_journal_start
>          __ext4_journal_start_sb
>              ext4_journal_check_start
>              jbd2__journal_start
>
> ext4_write_end
>      ext4_mark_inode_dirty
>          ext4_reserve_inode_write
>              ext4_journal_get_write_access
>                  jbd2_journal_get_write_access
>          ext4_mark_iloc_dirty
>              ext4_do_update_inode
>                  ext4_handle_dirty_metadata
>                      jbd2_journal_dirty_metadata
>
> 3.So I think we should put ocfs2_journal_access_di before
> ocfs2_journal_dirty in the ocfs2_write_end.
> and it works well after my modification.
>
> Signed-off-by: vicky <vicky.yangwenfang@huawei.com>
> ---
>   fs/ocfs2/aops.c | 21 ++++++++++-----------
>   1 file changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index d310d12..230e686 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -1818,16 +1818,6 @@ try_again:
>                  if (ret)
>                          goto out_commit;
>          }
> -       /*
> -        * We don't want this to fail in ocfs2_write_end(), so do it
> -        * here.
> -        */
> -       ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
> -                                     OCFS2_JOURNAL_ACCESS_WRITE);
> -       if (ret) {
> -               mlog_errno(ret);
> -               goto out_quota;
> -       }
>
>          /*
>           * Fill our page array first. That way we've grabbed enough so
> @@ -1978,7 +1968,7 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
>                             loff_t pos, unsigned len, unsigned copied,
>                             struct page *page, void *fsdata)
>   {
> -       int i;
> +       int i, ret;
>          unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
>          struct inode *inode = mapping->host;
>          struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> @@ -2028,6 +2018,14 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
>                  }
>          }
>
> +       ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
> +                                     OCFS2_JOURNAL_ACCESS_WRITE);
> +       if (ret) {
> +               copied = ret;
> +               mlog_errno(ret);
> +               goto out;
> +       }
> +
>   out_write_size:
>          pos += copied;
>          if (pos > i_size_read(inode)) {
> @@ -2042,6 +2040,7 @@ out_write_size:
>          ocfs2_update_inode_fsync_trans(handle, inode, 1);
>          ocfs2_journal_dirty(handle, wc->w_di_bh);
>
> +out:
>          ocfs2_commit_trans(osb, handle);
>
>          ocfs2_run_deallocs(osb, &wc->w_dealloc);
> --
> 1.8.3.4
>
>
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