From ed5fa5f0bac9868ce774c57b607063d0c666df4c Mon Sep 17 00:00:00 2001
From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Date: Tue, 31 May 2011 07:03:21 +0300
Subject: [PATCH] UBIFS: fix shrinker object count reports
BugLink: http://bugs.launchpad.net/bugs/802383
commit cf610bf4199770420629d3bc273494bd27ad6c1d upstream.
Sometimes VM asks the shrinker to return amount of objects it can shrink,
and we return the ubifs_clean_zn_cnt in that case. However, it is possible
that this counter is negative for a short period of time, due to the way
UBIFS TNC code updates it. And I can observe the following warnings sometimes:
shrink_slab: ubifs_shrinker+0x0/0x2b7 [ubifs] negative objects to delete nr=-8541616642706119788
This patch makes sure UBIFS never returns negative count of objects.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
fs/ubifs/shrinker.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/ubifs/shrinker.c b/fs/ubifs/shrinker.c
index 02feb59cefc..aec66890388 100644
--- a/fs/ubifs/shrinker.c
+++ b/fs/ubifs/shrinker.c
@@ -283,7 +283,11 @@ int ubifs_shrinker(int nr, gfp_t gfp_mask)
long clean_zn_cnt = atomic_long_read(&ubifs_clean_zn_cnt);
if (nr == 0)
- return clean_zn_cnt;
+ /*
+ * Due to the way UBIFS updates the clean znode counter it may
+ * temporarily be negative.
+ */
+ return clean_zn_cnt >= 0 ? clean_zn_cnt : 1;
if (!clean_zn_cnt) {
/*
--
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