ocfs2: call ocfs2_journal_access_di() before ocfs2_journal_dirty() in ocfs2_write_end...

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@huawei.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Zhangguanghui <zhang.guanghui@h3c.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index a7ab145e29014d3e3ee7d6a127de0967035e0eac..faf36a96cd19d023201acc434936fd133b7afc28 100644 (file)
--- a/fs/ocfs2/aops.c
+++ b/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 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);
@@ -2376,6 +2373,14 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
        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.