From: Dave Chinner <david@fromorbit.com>
Date: Wed, 28 Aug 2013 00:18:08 +0000 (+1000)
Subject: xfs: fix dquot isolation hang
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=35163417fb7a55a24b6b0ebb102e9991adf309aa;p=linux-beck.git

xfs: fix dquot isolation hang

The new LRU list isolation code in xfs_qm_dquot_isolate() isn't
completely up to date.  Firstly, it needs conversion to return enum
lru_status values, not raw numbers. Secondly - most importantly - it
fails to unlock the dquot and relock the LRU in the LRU_RETRY path.
This leads to deadlocks in xfstests generic/232. Fix them.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 1a4217e52c9f..a29169b062e3 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -707,7 +707,7 @@ xfs_qm_dquot_isolate(
 		trace_xfs_dqreclaim_want(dqp);
 		list_del_init(&dqp->q_lru);
 		XFS_STATS_DEC(xs_qm_dquot_unused);
-		return 0;
+		return LRU_REMOVED;
 	}
 
 	/*
@@ -753,17 +753,19 @@ xfs_qm_dquot_isolate(
 	XFS_STATS_DEC(xs_qm_dquot_unused);
 	trace_xfs_dqreclaim_done(dqp);
 	XFS_STATS_INC(xs_qm_dqreclaims);
-	return 0;
+	return LRU_REMOVED;
 
 out_miss_busy:
 	trace_xfs_dqreclaim_busy(dqp);
 	XFS_STATS_INC(xs_qm_dqreclaim_misses);
-	return 2;
+	return LRU_SKIP;
 
 out_unlock_dirty:
 	trace_xfs_dqreclaim_busy(dqp);
 	XFS_STATS_INC(xs_qm_dqreclaim_misses);
-	return 3;
+	xfs_dqunlock(dqp);
+	spin_lock(lru_lock);
+	return LRU_RETRY;
 }
 
 static unsigned long