JFFS2 issue with v3.5.x and later on Atmel chips at least (was: Kernel oops since v3.5.x on Atmel chips)

From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Date: Thu, 23 Aug 2012 10:10:07 +0300
Subject: [PATCH] JFFS2: fix unmount regression

This patch fixes regression introduced by
"8bdc81c jffs2: get rid of jffs2_sync_super". We submit a delayed work in order
to make sure the write-buffer is synchronized at some point. But we do not
flush it when we unmount, which causes an oops when we unmount the file-system
and then the delayed work is executed.

This patch fixes the issue by adding a "cancel_delayed_work_sync()" infocation
in the '->sync_fs()' handler. This will make sure the delayed work is canceled
on sync, unmount and re-mount. And because VFS always callse 'sync_fs()' before
unmounting or remounting, this fixes the issue.

Reported-by: Ludovic Desroches <redacted>
Cc: stable at vger.kernel.org [3.5+]
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
---

Ludovic, would you please give this patch a test? Also attached.

 fs/jffs2/super.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index 61ea413..e385fa3 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c

@@ -100,6 +100,9 @@ static int jffs2_sync_fs(struct super_block *sb, int wait)
 {
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
 
+	if (IS_ENABLED(CONFIG_JFFS2_FS_WRITEBUFFER))
+		cancel_delayed_work_sync(&c->wbuf_dwork);
+
 	mutex_lock(&c->alloc_sem);
 	jffs2_flush_wbuf_pad(c);
 	mutex_unlock(&c->alloc_sem);

-- 
1.7.10.4
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