JFFS2: fix unmount regression

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=a445f784ae5558a3da680aa6b39ed53c95a551c1
Commit:     a445f784ae5558a3da680aa6b39ed53c95a551c1
Parent:     b05a1187bbf35035300313987cbd22e362d71dc6
Author:     Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
AuthorDate: Thu Aug 23 10:10:07 2012 +0300
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Sat Sep 29 14:58:42 2012 +0100

    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 <ludovic.desroches at atmel.com>
    Cc: stable at vger.kernel.org [3.5+]
    Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
    Tested-by: Ludovic Desroches <ludovic.desroches at atmel.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 fs/jffs2/super.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index 61ea413..1224d6b 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -100,6 +100,10 @@ static int jffs2_sync_fs(struct super_block *sb, int wait)
 {
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
 
+#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
+	cancel_delayed_work_sync(&c->wbuf_dwork);
+#endif
+
 	mutex_lock(&c->alloc_sem);
 	jffs2_flush_wbuf_pad(c);
 	mutex_unlock(&c->alloc_sem);