[PATCH] ext4: memory leakage in ext4_discard_preallocations

[jing zhang <zj.barak@gmail.com>]

From: Jing Zhang <zj.barak@gmail.com>

Date: Thu Mar 18 20:33:44 2010

When unexpected errors occur, there is memory leakage, and more.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Jing Zhang <zj.barak@gmail.com>

---

--- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
+++ zj/mballoc.c	2010-03-18 20:41:32.000000000 +0800
@@ -3717,6 +3717,7 @@ void ext4_discard_preallocations(struct
 	struct list_head list;
 	struct ext4_buddy e4b;
 	int err;
+	int occurs = 0;

 	if (!S_ISREG(inode->i_mode)) {
 		/*BUG_ON(!list_empty(&ei->i_prealloc_list));*/
@@ -3781,6 +3782,7 @@ repeat:
 	}
 	spin_unlock(&ei->i_prealloc_lock);

+best_efforts:
 	list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
 		BUG_ON(pa->pa_type != MB_INODE_PA);
 		ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, NULL);
@@ -3811,6 +3813,12 @@ repeat:
 		list_del(&pa->u.pa_tmp_list);
 		call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
 	}
+	if (! list_empty(&list)) {
+		if (occurs++ < 2)
+			goto best_efforts;
+		else
+			BUG();
+	}
 	if (ac)
 		kmem_cache_free(ext4_ac_cachep, ac);
 }