Ocfs2 devel - Aug 2015 - [patch 17/28] ocfs2: call ocfs2_journal_access_di() before ocfs2_journal_dirty() in ocfs2_write_end_nolock()

From: yangwenfang <vicky.yangwenfang at huawei.com>
Subject: ocfs2: call ocfs2_journal_access_di() before ocfs2_journal_dirty() in
ocfs2_write_end_nolock()

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
                                        (jh->b_transaction = NULL)
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 at huawei.com>
Cc: Mark Fasheh <mfasheh at suse.com>
Cc: Joel Becker <jlbec at evilplan.org>
Cc: Zhangguanghui <zhang.guanghui at h3c.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
---

 fs/ocfs2/aops.c |   16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff -puN
fs/ocfs2/aops.c~ocfs2-call-ocfs2_journal_access_di-before-ocfs2_journal_dirty-in-ocfs2_write_end_nolock
fs/ocfs2/aops.c
---
a/fs/ocfs2/aops.c~ocfs2-call-ocfs2_journal_access_di-before-ocfs2_journal_dirty-in-ocfs2_write_end_nolock
+++ a/fs/ocfs2/aops.c
@@ -2207,10 +2207,7 @@ 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) {
@@ -2367,7 +2364,7 @@ int ocfs2_write_end_nolock(struct addres
 			   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);
@@ -2376,6 +2373,14 @@ int ocfs2_write_end_nolock(struct addres
 	handle_t *handle = wc->w_handle;
 	struct page *tmppage;
 
+	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;
+	}
+
 	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
 		ocfs2_write_end_inline(inode, pos, len, &copied, di, wc);
 		goto out_write_size;
@@ -2431,6 +2436,7 @@ out_write_size:
 	ocfs2_update_inode_fsync_trans(handle, inode, 1);
 	ocfs2_journal_dirty(handle, wc->w_di_bh);
 
+out:
 	/* unlock pages before dealloc since it needs acquiring j_trans_barrier
 	 * lock, or it will cause a deadlock since journal commit threads holds
 	 * this lock and will ask for the page lock when flushing the data.
_

On Wed, Aug 26, 2015 at 03:12:06PM -0700, Andrew Morton
wrote:
> From: yangwenfang <vicky.yangwenfang at huawei.com>
> Subject: ocfs2: call ocfs2_journal_access_di() before ocfs2_journal_dirty()
in ocfs2_write_end_nolock()
> 
> 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
>                                         (jh->b_transaction = NULL)
> 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 at huawei.com>
> Cc: Mark Fasheh <mfasheh at suse.com>
> Cc: Joel Becker <jlbec at evilplan.org>
> Cc: Zhangguanghui <zhang.guanghui at h3c.com>
> Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Reviewed-by: Mark Fasheh <mfasheh at suse.de>
	--Mark

--
Mark Fasheh