ocfs2: fix possible double free in ocfs2_write_begin_nolock

When ocfs2_write_cluster_by_desc() failed in ocfs2_write_begin_nolock()
because of ENOSPC, it goes to out_quota, freeing data_ac(meta_ac).  Then
it calls ocfs2_try_to_free_truncate_log() to free space.  If enough
space freed, it will try to write again.  Unfortunately, some error
happenes before ocfs2_lock_allocators(), it goes to out and free
data_ac(meta_ac) again.

Signed-off-by: joyce <xuejiufei@huawei.com>
Reviewed-by: Jie Liu <jeff.liu@oracle.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index c20360002f29..f959a1532767 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1898,10 +1898,14 @@ out_commit:
 out:
         ocfs2_free_write_ctxt(wc);
 
-        if (data_ac)
+        if (data_ac) {
                 ocfs2_free_alloc_context(data_ac);
-        if (meta_ac)
+                data_ac = NULL;
+        }
+        if (meta_ac) {
                 ocfs2_free_alloc_context(meta_ac);
+                meta_ac = NULL;
+        }
 
         if (ret == -ENOSPC && try_free) {
                 /*